drivers/gpu/drm/dp/drm_dp_mst_topology.c

   1 /*
   2  * Copyright © 2014 Red Hat
   3  *
   4  * Permission to use, copy, modify, distribute, and sell this software and its
   5  * documentation for any purpose is hereby granted without fee, provided that
   6  * the above copyright notice appear in all copies and that both that copyright
   7  * notice and this permission notice appear in supporting documentation, and
   8  * that the name of the copyright holders not be used in advertising or
   9  * publicity pertaining to distribution of the software without specific,
  10  * written prior permission.  The copyright holders make no representations
  11  * about the suitability of this software for any purpose.  It is provided "as
  12  * is" without express or implied warranty.
  13  *
  14  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  15  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  16  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  17  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  18  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  19  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  20  * OF THIS SOFTWARE.
  21  */
  22
  23 #include <linux/bitfield.h>
  24 #include <linux/delay.h>
  25 #include <linux/errno.h>
  26 #include <linux/i2c.h>
  27 #include <linux/init.h>
  28 #include <linux/kernel.h>
  29 #include <linux/random.h>
  30 #include <linux/sched.h>
  31 #include <linux/seq_file.h>
  32 #include <linux/iopoll.h>
  33
  34 #if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
  35 #include <linux/stacktrace.h>
  36 #include <linux/sort.h>
  37 #include <linux/timekeeping.h>
  38 #include <linux/math64.h>
  39 #endif
  40
  41 #include <drm/dp/drm_dp_mst_helper.h>
  42 #include <drm/drm_atomic.h>
  43 #include <drm/drm_atomic_helper.h>
  44 #include <drm/drm_drv.h>
  45 #include <drm/drm_print.h>
  46 #include <drm/drm_probe_helper.h>
  47
  48 #include "drm_dp_helper_internal.h"
  49 #include "drm_dp_mst_topology_internal.h"
  50
  51 /**
  52  * DOC: dp mst helper
  53  *
  54  * These functions contain parts of the DisplayPort 1.2a MultiStream Transport
  55  * protocol. The helpers contain a topology manager and bandwidth manager.
  56  * The helpers encapsulate the sending and received of sideband msgs.
  57  */
  58 struct drm_dp_pending_up_req {
  59         struct drm_dp_sideband_msg_hdr hdr;
  60         struct drm_dp_sideband_msg_req_body msg;
  61         struct list_head next;
  62 };
  63
  64 static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
  65                                   char *buf);
  66
  67 static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port);
  68
  69 static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
  70                                      int id,
  71                                      struct drm_dp_payload *payload);
  72
  73 static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
  74                                  struct drm_dp_mst_port *port,
  75                                  int offset, int size, u8 *bytes);
  76 static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
  77                                   struct drm_dp_mst_port *port,
  78                                   int offset, int size, u8 *bytes);
  79
  80 static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
  81                                     struct drm_dp_mst_branch *mstb);
  82
  83 static void
  84 drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr,
  85                                    struct drm_dp_mst_branch *mstb);
  86
  87 static int drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
  88                                            struct drm_dp_mst_branch *mstb,
  89                                            struct drm_dp_mst_port *port);
  90 static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
  91                                  u8 *guid);
  92
  93 static int drm_dp_mst_register_i2c_bus(struct drm_dp_mst_port *port);
  94 static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_mst_port *port);
  95 static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr);
  96
  97 static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port,
  98                                                  struct drm_dp_mst_branch *branch);
  99
 100 #define DBG_PREFIX "[dp_mst]"
 101
 102 #define DP_STR(x) [DP_ ## x] = #x
 103
 104 static const char *drm_dp_mst_req_type_str(u8 req_type)
 105 {
 106         static const char * const req_type_str[] = {
 107                 DP_STR(GET_MSG_TRANSACTION_VERSION),
 108                 DP_STR(LINK_ADDRESS),
 109                 DP_STR(CONNECTION_STATUS_NOTIFY),
 110                 DP_STR(ENUM_PATH_RESOURCES),
 111                 DP_STR(ALLOCATE_PAYLOAD),
 112                 DP_STR(QUERY_PAYLOAD),
 113                 DP_STR(RESOURCE_STATUS_NOTIFY),
 114                 DP_STR(CLEAR_PAYLOAD_ID_TABLE),
 115                 DP_STR(REMOTE_DPCD_READ),
 116                 DP_STR(REMOTE_DPCD_WRITE),
 117                 DP_STR(REMOTE_I2C_READ),
 118                 DP_STR(REMOTE_I2C_WRITE),
 119                 DP_STR(POWER_UP_PHY),
 120                 DP_STR(POWER_DOWN_PHY),
 121                 DP_STR(SINK_EVENT_NOTIFY),
 122                 DP_STR(QUERY_STREAM_ENC_STATUS),
 123         };
 124
 125         if (req_type >= ARRAY_SIZE(req_type_str) ||
 126             !req_type_str[req_type])
 127                 return "unknown";
 128
 129         return req_type_str[req_type];
 130 }
 131
 132 #undef DP_STR
 133 #define DP_STR(x) [DP_NAK_ ## x] = #x
 134
 135 static const char *drm_dp_mst_nak_reason_str(u8 nak_reason)
 136 {
 137         static const char * const nak_reason_str[] = {
 138                 DP_STR(WRITE_FAILURE),
 139                 DP_STR(INVALID_READ),
 140                 DP_STR(CRC_FAILURE),
 141                 DP_STR(BAD_PARAM),
 142                 DP_STR(DEFER),
 143                 DP_STR(LINK_FAILURE),
 144                 DP_STR(NO_RESOURCES),
 145                 DP_STR(DPCD_FAIL),
 146                 DP_STR(I2C_NAK),
 147                 DP_STR(ALLOCATE_FAIL),
 148         };
 149
 150         if (nak_reason >= ARRAY_SIZE(nak_reason_str) ||
 151             !nak_reason_str[nak_reason])
 152                 return "unknown";
 153
 154         return nak_reason_str[nak_reason];
 155 }
 156
 157 #undef DP_STR
 158 #define DP_STR(x) [DRM_DP_SIDEBAND_TX_ ## x] = #x
 159
 160 static const char *drm_dp_mst_sideband_tx_state_str(int state)
 161 {
 162         static const char * const sideband_reason_str[] = {
 163                 DP_STR(QUEUED),
 164                 DP_STR(START_SEND),
 165                 DP_STR(SENT),
 166                 DP_STR(RX),
 167                 DP_STR(TIMEOUT),
 168         };
 169
 170         if (state >= ARRAY_SIZE(sideband_reason_str) ||
 171             !sideband_reason_str[state])
 172                 return "unknown";
 173
 174         return sideband_reason_str[state];
 175 }
 176
 177 static int
 178 drm_dp_mst_rad_to_str(const u8 rad[8], u8 lct, char *out, size_t len)
 179 {
 180         int i;
 181         u8 unpacked_rad[16];
 182
 183         for (i = 0; i < lct; i++) {
 184                 if (i % 2)
 185                         unpacked_rad[i] = rad[i / 2] >> 4;
 186                 else
 187                         unpacked_rad[i] = rad[i / 2] & BIT_MASK(4);
 188         }
 189
 190         /* TODO: Eventually add something to printk so we can format the rad
 191          * like this: 1.2.3
 192          */
 193         return snprintf(out, len, "%*phC", lct, unpacked_rad);
 194 }
 195
 196 /* sideband msg handling */
 197 static u8 drm_dp_msg_header_crc4(const uint8_t *data, size_t num_nibbles)
 198 {
 199         u8 bitmask = 0x80;
 200         u8 bitshift = 7;
 201         u8 array_index = 0;
 202         int number_of_bits = num_nibbles * 4;
 203         u8 remainder = 0;
 204
 205         while (number_of_bits != 0) {
 206                 number_of_bits--;
 207                 remainder <<= 1;
 208                 remainder |= (data[array_index] & bitmask) >> bitshift;
 209                 bitmask >>= 1;
 210                 bitshift--;
 211                 if (bitmask == 0) {
 212                         bitmask = 0x80;
 213                         bitshift = 7;
 214                         array_index++;
 215                 }
 216                 if ((remainder & 0x10) == 0x10)
 217                         remainder ^= 0x13;
 218         }
 219
 220         number_of_bits = 4;
 221         while (number_of_bits != 0) {
 222                 number_of_bits--;
 223                 remainder <<= 1;
 224                 if ((remainder & 0x10) != 0)
 225                         remainder ^= 0x13;
 226         }
 227
 228         return remainder;
 229 }
 230
 231 static u8 drm_dp_msg_data_crc4(const uint8_t *data, u8 number_of_bytes)
 232 {
 233         u8 bitmask = 0x80;
 234         u8 bitshift = 7;
 235         u8 array_index = 0;
 236         int number_of_bits = number_of_bytes * 8;
 237         u16 remainder = 0;
 238
 239         while (number_of_bits != 0) {
 240                 number_of_bits--;
 241                 remainder <<= 1;
 242                 remainder |= (data[array_index] & bitmask) >> bitshift;
 243                 bitmask >>= 1;
 244                 bitshift--;
 245                 if (bitmask == 0) {
 246                         bitmask = 0x80;
 247                         bitshift = 7;
 248                         array_index++;
 249                 }
 250                 if ((remainder & 0x100) == 0x100)
 251                         remainder ^= 0xd5;
 252         }
 253
 254         number_of_bits = 8;
 255         while (number_of_bits != 0) {
 256                 number_of_bits--;
 257                 remainder <<= 1;
 258                 if ((remainder & 0x100) != 0)
 259                         remainder ^= 0xd5;
 260         }
 261
 262         return remainder & 0xff;
 263 }
 264 static inline u8 drm_dp_calc_sb_hdr_size(struct drm_dp_sideband_msg_hdr *hdr)
 265 {
 266         u8 size = 3;
 267
 268         size += (hdr->lct / 2);
 269         return size;
 270 }
 271
 272 static void drm_dp_encode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr,
 273                                            u8 *buf, int *len)
 274 {
 275         int idx = 0;
 276         int i;
 277         u8 crc4;
 278
 279         buf[idx++] = ((hdr->lct & 0xf) << 4) | (hdr->lcr & 0xf);
 280         for (i = 0; i < (hdr->lct / 2); i++)
 281                 buf[idx++] = hdr->rad[i];
 282         buf[idx++] = (hdr->broadcast << 7) | (hdr->path_msg << 6) |
 283                 (hdr->msg_len & 0x3f);
 284         buf[idx++] = (hdr->somt << 7) | (hdr->eomt << 6) | (hdr->seqno << 4);
 285
 286         crc4 = drm_dp_msg_header_crc4(buf, (idx * 2) - 1);
 287         buf[idx - 1] |= (crc4 & 0xf);
 288
 289         *len = idx;
 290 }
 291
 292 static bool drm_dp_decode_sideband_msg_hdr(const struct drm_dp_mst_topology_mgr *mgr,
 293                                            struct drm_dp_sideband_msg_hdr *hdr,
 294                                            u8 *buf, int buflen, u8 *hdrlen)
 295 {
 296         u8 crc4;
 297         u8 len;
 298         int i;
 299         u8 idx;
 300
 301         if (buf[0] == 0)
 302                 return false;
 303         len = 3;
 304         len += ((buf[0] & 0xf0) >> 4) / 2;
 305         if (len > buflen)
 306                 return false;
 307         crc4 = drm_dp_msg_header_crc4(buf, (len * 2) - 1);
 308
 309         if ((crc4 & 0xf) != (buf[len - 1] & 0xf)) {
 310                 drm_dbg_kms(mgr->dev, "crc4 mismatch 0x%x 0x%x\n", crc4, buf[len - 1]);
 311                 return false;
 312         }
 313
 314         hdr->lct = (buf[0] & 0xf0) >> 4;
 315         hdr->lcr = (buf[0] & 0xf);
 316         idx = 1;
 317         for (i = 0; i < (hdr->lct / 2); i++)
 318                 hdr->rad[i] = buf[idx++];
 319         hdr->broadcast = (buf[idx] >> 7) & 0x1;
 320         hdr->path_msg = (buf[idx] >> 6) & 0x1;
 321         hdr->msg_len = buf[idx] & 0x3f;
 322         idx++;
 323         hdr->somt = (buf[idx] >> 7) & 0x1;
 324         hdr->eomt = (buf[idx] >> 6) & 0x1;
 325         hdr->seqno = (buf[idx] >> 4) & 0x1;
 326         idx++;
 327         *hdrlen = idx;
 328         return true;
 329 }
 330
 331 void
 332 drm_dp_encode_sideband_req(const struct drm_dp_sideband_msg_req_body *req,
 333                            struct drm_dp_sideband_msg_tx *raw)
 334 {
 335         int idx = 0;
 336         int i;
 337         u8 *buf = raw->msg;
 338
 339         buf[idx++] = req->req_type & 0x7f;
 340
 341         switch (req->req_type) {
 342         case DP_ENUM_PATH_RESOURCES:
 343         case DP_POWER_DOWN_PHY:
 344         case DP_POWER_UP_PHY:
 345                 buf[idx] = (req->u.port_num.port_number & 0xf) << 4;
 346                 idx++;
 347                 break;
 348         case DP_ALLOCATE_PAYLOAD:
 349                 buf[idx] = (req->u.allocate_payload.port_number & 0xf) << 4 |
 350                         (req->u.allocate_payload.number_sdp_streams & 0xf);
 351                 idx++;
 352                 buf[idx] = (req->u.allocate_payload.vcpi & 0x7f);
 353                 idx++;
 354                 buf[idx] = (req->u.allocate_payload.pbn >> 8);
 355                 idx++;
 356                 buf[idx] = (req->u.allocate_payload.pbn & 0xff);
 357                 idx++;
 358                 for (i = 0; i < req->u.allocate_payload.number_sdp_streams / 2; i++) {
 359                         buf[idx] = ((req->u.allocate_payload.sdp_stream_sink[i * 2] & 0xf) << 4) |
 360                                 (req->u.allocate_payload.sdp_stream_sink[i * 2 + 1] & 0xf);
 361                         idx++;
 362                 }
 363                 if (req->u.allocate_payload.number_sdp_streams & 1) {
 364                         i = req->u.allocate_payload.number_sdp_streams - 1;
 365                         buf[idx] = (req->u.allocate_payload.sdp_stream_sink[i] & 0xf) << 4;
 366                         idx++;
 367                 }
 368                 break;
 369         case DP_QUERY_PAYLOAD:
 370                 buf[idx] = (req->u.query_payload.port_number & 0xf) << 4;
 371                 idx++;
 372                 buf[idx] = (req->u.query_payload.vcpi & 0x7f);
 373                 idx++;
 374                 break;
 375         case DP_REMOTE_DPCD_READ:
 376                 buf[idx] = (req->u.dpcd_read.port_number & 0xf) << 4;
 377                 buf[idx] |= ((req->u.dpcd_read.dpcd_address & 0xf0000) >> 16) & 0xf;
 378                 idx++;
 379                 buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff00) >> 8;
 380                 idx++;
 381                 buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff);
 382                 idx++;
 383                 buf[idx] = (req->u.dpcd_read.num_bytes);
 384                 idx++;
 385                 break;
 386
 387         case DP_REMOTE_DPCD_WRITE:
 388                 buf[idx] = (req->u.dpcd_write.port_number & 0xf) << 4;
 389                 buf[idx] |= ((req->u.dpcd_write.dpcd_address & 0xf0000) >> 16) & 0xf;
 390                 idx++;
 391                 buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff00) >> 8;
 392                 idx++;
 393                 buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff);
 394                 idx++;
 395                 buf[idx] = (req->u.dpcd_write.num_bytes);
 396                 idx++;
 397                 memcpy(&buf[idx], req->u.dpcd_write.bytes, req->u.dpcd_write.num_bytes);
 398                 idx += req->u.dpcd_write.num_bytes;
 399                 break;
 400         case DP_REMOTE_I2C_READ:
 401                 buf[idx] = (req->u.i2c_read.port_number & 0xf) << 4;
 402                 buf[idx] |= (req->u.i2c_read.num_transactions & 0x3);
 403                 idx++;
 404                 for (i = 0; i < (req->u.i2c_read.num_transactions & 0x3); i++) {
 405                         buf[idx] = req->u.i2c_read.transactions[i].i2c_dev_id & 0x7f;
 406                         idx++;
 407                         buf[idx] = req->u.i2c_read.transactions[i].num_bytes;
 408                         idx++;
 409                         memcpy(&buf[idx], req->u.i2c_read.transactions[i].bytes, req->u.i2c_read.transactions[i].num_bytes);
 410                         idx += req->u.i2c_read.transactions[i].num_bytes;
 411
 412                         buf[idx] = (req->u.i2c_read.transactions[i].no_stop_bit & 0x1) << 4;
 413                         buf[idx] |= (req->u.i2c_read.transactions[i].i2c_transaction_delay & 0xf);
 414                         idx++;
 415                 }
 416                 buf[idx] = (req->u.i2c_read.read_i2c_device_id) & 0x7f;
 417                 idx++;
 418                 buf[idx] = (req->u.i2c_read.num_bytes_read);
 419                 idx++;
 420                 break;
 421
 422         case DP_REMOTE_I2C_WRITE:
 423                 buf[idx] = (req->u.i2c_write.port_number & 0xf) << 4;
 424                 idx++;
 425                 buf[idx] = (req->u.i2c_write.write_i2c_device_id) & 0x7f;
 426                 idx++;
 427                 buf[idx] = (req->u.i2c_write.num_bytes);
 428                 idx++;
 429                 memcpy(&buf[idx], req->u.i2c_write.bytes, req->u.i2c_write.num_bytes);
 430                 idx += req->u.i2c_write.num_bytes;
 431                 break;
 432         case DP_QUERY_STREAM_ENC_STATUS: {
 433                 const struct drm_dp_query_stream_enc_status *msg;
 434
 435                 msg = &req->u.enc_status;
 436                 buf[idx] = msg->stream_id;
 437                 idx++;
 438                 memcpy(&buf[idx], msg->client_id, sizeof(msg->client_id));
 439                 idx += sizeof(msg->client_id);
 440                 buf[idx] = 0;
 441                 buf[idx] |= FIELD_PREP(GENMASK(1, 0), msg->stream_event);
 442                 buf[idx] |= msg->valid_stream_event ? BIT(2) : 0;
 443                 buf[idx] |= FIELD_PREP(GENMASK(4, 3), msg->stream_behavior);
 444                 buf[idx] |= msg->valid_stream_behavior ? BIT(5) : 0;
 445                 idx++;
 446                 }
 447                 break;
 448         }
 449         raw->cur_len = idx;
 450 }
 451 EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_encode_sideband_req);
 452
 453 /* Decode a sideband request we've encoded, mainly used for debugging */
 454 int
 455 drm_dp_decode_sideband_req(const struct drm_dp_sideband_msg_tx *raw,
 456                            struct drm_dp_sideband_msg_req_body *req)
 457 {
 458         const u8 *buf = raw->msg;
 459         int i, idx = 0;
 460
 461         req->req_type = buf[idx++] & 0x7f;
 462         switch (req->req_type) {
 463         case DP_ENUM_PATH_RESOURCES:
 464         case DP_POWER_DOWN_PHY:
 465         case DP_POWER_UP_PHY:
 466                 req->u.port_num.port_number = (buf[idx] >> 4) & 0xf;
 467                 break;
 468         case DP_ALLOCATE_PAYLOAD:
 469                 {
 470                         struct drm_dp_allocate_payload *a =
 471                                 &req->u.allocate_payload;
 472
 473                         a->number_sdp_streams = buf[idx] & 0xf;
 474                         a->port_number = (buf[idx] >> 4) & 0xf;
 475
 476                         WARN_ON(buf[++idx] & 0x80);
 477                         a->vcpi = buf[idx] & 0x7f;
 478
 479                         a->pbn = buf[++idx] << 8;
 480                         a->pbn |= buf[++idx];
 481
 482                         idx++;
 483                         for (i = 0; i < a->number_sdp_streams; i++) {
 484                                 a->sdp_stream_sink[i] =
 485                                         (buf[idx + (i / 2)] >> ((i % 2) ? 0 : 4)) & 0xf;
 486                         }
 487                 }
 488                 break;
 489         case DP_QUERY_PAYLOAD:
 490                 req->u.query_payload.port_number = (buf[idx] >> 4) & 0xf;
 491                 WARN_ON(buf[++idx] & 0x80);
 492                 req->u.query_payload.vcpi = buf[idx] & 0x7f;
 493                 break;
 494         case DP_REMOTE_DPCD_READ:
 495                 {
 496                         struct drm_dp_remote_dpcd_read *r = &req->u.dpcd_read;
 497
 498                         r->port_number = (buf[idx] >> 4) & 0xf;
 499
 500                         r->dpcd_address = (buf[idx] << 16) & 0xf0000;
 501                         r->dpcd_address |= (buf[++idx] << 8) & 0xff00;
 502                         r->dpcd_address |= buf[++idx] & 0xff;
 503
 504                         r->num_bytes = buf[++idx];
 505                 }
 506                 break;
 507         case DP_REMOTE_DPCD_WRITE:
 508                 {
 509                         struct drm_dp_remote_dpcd_write *w =
 510                                 &req->u.dpcd_write;
 511
 512                         w->port_number = (buf[idx] >> 4) & 0xf;
 513
 514                         w->dpcd_address = (buf[idx] << 16) & 0xf0000;
 515                         w->dpcd_address |= (buf[++idx] << 8) & 0xff00;
 516                         w->dpcd_address |= buf[++idx] & 0xff;
 517
 518                         w->num_bytes = buf[++idx];
 519
 520                         w->bytes = kmemdup(&buf[++idx], w->num_bytes,
 521                                            GFP_KERNEL);
 522                         if (!w->bytes)
 523                                 return -ENOMEM;
 524                 }
 525                 break;
 526         case DP_REMOTE_I2C_READ:
 527                 {
 528                         struct drm_dp_remote_i2c_read *r = &req->u.i2c_read;
 529                         struct drm_dp_remote_i2c_read_tx *tx;
 530                         bool failed = false;
 531
 532                         r->num_transactions = buf[idx] & 0x3;
 533                         r->port_number = (buf[idx] >> 4) & 0xf;
 534                         for (i = 0; i < r->num_transactions; i++) {
 535                                 tx = &r->transactions[i];
 536
 537                                 tx->i2c_dev_id = buf[++idx] & 0x7f;
 538                                 tx->num_bytes = buf[++idx];
 539                                 tx->bytes = kmemdup(&buf[++idx],
 540                                                     tx->num_bytes,
 541                                                     GFP_KERNEL);
 542                                 if (!tx->bytes) {
 543                                         failed = true;
 544                                         break;
 545                                 }
 546                                 idx += tx->num_bytes;
 547                                 tx->no_stop_bit = (buf[idx] >> 5) & 0x1;
 548                                 tx->i2c_transaction_delay = buf[idx] & 0xf;
 549                         }
 550
 551                         if (failed) {
 552                                 for (i = 0; i < r->num_transactions; i++) {
 553                                         tx = &r->transactions[i];
 554                                         kfree(tx->bytes);
 555                                 }
 556                                 return -ENOMEM;
 557                         }
 558
 559                         r->read_i2c_device_id = buf[++idx] & 0x7f;
 560                         r->num_bytes_read = buf[++idx];
 561                 }
 562                 break;
 563         case DP_REMOTE_I2C_WRITE:
 564                 {
 565                         struct drm_dp_remote_i2c_write *w = &req->u.i2c_write;
 566
 567                         w->port_number = (buf[idx] >> 4) & 0xf;
 568                         w->write_i2c_device_id = buf[++idx] & 0x7f;
 569                         w->num_bytes = buf[++idx];
 570                         w->bytes = kmemdup(&buf[++idx], w->num_bytes,
 571                                            GFP_KERNEL);
 572                         if (!w->bytes)
 573                                 return -ENOMEM;
 574                 }
 575                 break;
 576         case DP_QUERY_STREAM_ENC_STATUS:
 577                 req->u.enc_status.stream_id = buf[idx++];
 578                 for (i = 0; i < sizeof(req->u.enc_status.client_id); i++)
 579                         req->u.enc_status.client_id[i] = buf[idx++];
 580
 581                 req->u.enc_status.stream_event = FIELD_GET(GENMASK(1, 0),
 582                                                            buf[idx]);
 583                 req->u.enc_status.valid_stream_event = FIELD_GET(BIT(2),
 584                                                                  buf[idx]);
 585                 req->u.enc_status.stream_behavior = FIELD_GET(GENMASK(4, 3),
 586                                                               buf[idx]);
 587                 req->u.enc_status.valid_stream_behavior = FIELD_GET(BIT(5),
 588                                                                     buf[idx]);
 589                 break;
 590         }
 591
 592         return 0;
 593 }
 594 EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_decode_sideband_req);
 595
 596 void
 597 drm_dp_dump_sideband_msg_req_body(const struct drm_dp_sideband_msg_req_body *req,
 598                                   int indent, struct drm_printer *printer)
 599 {
 600         int i;
 601
 602 #define P(f, ...) drm_printf_indent(printer, indent, f, ##__VA_ARGS__)
 603         if (req->req_type == DP_LINK_ADDRESS) {
 604                 /* No contents to print */
 605                 P("type=%s\n", drm_dp_mst_req_type_str(req->req_type));
 606                 return;
 607         }
 608
 609         P("type=%s contents:\n", drm_dp_mst_req_type_str(req->req_type));
 610         indent++;
 611
 612         switch (req->req_type) {
 613         case DP_ENUM_PATH_RESOURCES:
 614         case DP_POWER_DOWN_PHY:
 615         case DP_POWER_UP_PHY:
 616                 P("port=%d\n", req->u.port_num.port_number);
 617                 break;
 618         case DP_ALLOCATE_PAYLOAD:
 619                 P("port=%d vcpi=%d pbn=%d sdp_streams=%d %*ph\n",
 620                   req->u.allocate_payload.port_number,
 621                   req->u.allocate_payload.vcpi, req->u.allocate_payload.pbn,
 622                   req->u.allocate_payload.number_sdp_streams,
 623                   req->u.allocate_payload.number_sdp_streams,
 624                   req->u.allocate_payload.sdp_stream_sink);
 625                 break;
 626         case DP_QUERY_PAYLOAD:
 627                 P("port=%d vcpi=%d\n",
 628                   req->u.query_payload.port_number,
 629                   req->u.query_payload.vcpi);
 630                 break;
 631         case DP_REMOTE_DPCD_READ:
 632                 P("port=%d dpcd_addr=%05x len=%d\n",
 633                   req->u.dpcd_read.port_number, req->u.dpcd_read.dpcd_address,
 634                   req->u.dpcd_read.num_bytes);
 635                 break;
 636         case DP_REMOTE_DPCD_WRITE:
 637                 P("port=%d addr=%05x len=%d: %*ph\n",
 638                   req->u.dpcd_write.port_number,
 639                   req->u.dpcd_write.dpcd_address,
 640                   req->u.dpcd_write.num_bytes, req->u.dpcd_write.num_bytes,
 641                   req->u.dpcd_write.bytes);
 642                 break;
 643         case DP_REMOTE_I2C_READ:
 644                 P("port=%d num_tx=%d id=%d size=%d:\n",
 645                   req->u.i2c_read.port_number,
 646                   req->u.i2c_read.num_transactions,
 647                   req->u.i2c_read.read_i2c_device_id,
 648                   req->u.i2c_read.num_bytes_read);
 649
 650                 indent++;
 651                 for (i = 0; i < req->u.i2c_read.num_transactions; i++) {
 652                         const struct drm_dp_remote_i2c_read_tx *rtx =
 653                                 &req->u.i2c_read.transactions[i];
 654
 655                         P("%d: id=%03d size=%03d no_stop_bit=%d tx_delay=%03d: %*ph\n",
 656                           i, rtx->i2c_dev_id, rtx->num_bytes,
 657                           rtx->no_stop_bit, rtx->i2c_transaction_delay,
 658                           rtx->num_bytes, rtx->bytes);
 659                 }
 660                 break;
 661         case DP_REMOTE_I2C_WRITE:
 662                 P("port=%d id=%d size=%d: %*ph\n",
 663                   req->u.i2c_write.port_number,
 664                   req->u.i2c_write.write_i2c_device_id,
 665                   req->u.i2c_write.num_bytes, req->u.i2c_write.num_bytes,
 666                   req->u.i2c_write.bytes);
 667                 break;
 668         case DP_QUERY_STREAM_ENC_STATUS:
 669                 P("stream_id=%u client_id=%*ph stream_event=%x "
 670                   "valid_event=%d stream_behavior=%x valid_behavior=%d",
 671                   req->u.enc_status.stream_id,
 672                   (int)ARRAY_SIZE(req->u.enc_status.client_id),
 673                   req->u.enc_status.client_id, req->u.enc_status.stream_event,
 674                   req->u.enc_status.valid_stream_event,
 675                   req->u.enc_status.stream_behavior,
 676                   req->u.enc_status.valid_stream_behavior);
 677                 break;
 678         default:
 679                 P("???\n");
 680                 break;
 681         }
 682 #undef P
 683 }
 684 EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_dump_sideband_msg_req_body);
 685
 686 static inline void
 687 drm_dp_mst_dump_sideband_msg_tx(struct drm_printer *p,
 688                                 const struct drm_dp_sideband_msg_tx *txmsg)
 689 {
 690         struct drm_dp_sideband_msg_req_body req;
 691         char buf[64];
 692         int ret;
 693         int i;
 694
 695         drm_dp_mst_rad_to_str(txmsg->dst->rad, txmsg->dst->lct, buf,
 696                               sizeof(buf));
 697         drm_printf(p, "txmsg cur_offset=%x cur_len=%x seqno=%x state=%s path_msg=%d dst=%s\n",
 698                    txmsg->cur_offset, txmsg->cur_len, txmsg->seqno,
 699                    drm_dp_mst_sideband_tx_state_str(txmsg->state),
 700                    txmsg->path_msg, buf);
 701
 702         ret = drm_dp_decode_sideband_req(txmsg, &req);
 703         if (ret) {
 704                 drm_printf(p, "<failed to decode sideband req: %d>\n", ret);
 705                 return;
 706         }
 707         drm_dp_dump_sideband_msg_req_body(&req, 1, p);
 708
 709         switch (req.req_type) {
 710         case DP_REMOTE_DPCD_WRITE:
 711                 kfree(req.u.dpcd_write.bytes);
 712                 break;
 713         case DP_REMOTE_I2C_READ:
 714                 for (i = 0; i < req.u.i2c_read.num_transactions; i++)
 715                         kfree(req.u.i2c_read.transactions[i].bytes);
 716                 break;
 717         case DP_REMOTE_I2C_WRITE:
 718                 kfree(req.u.i2c_write.bytes);
 719                 break;
 720         }
 721 }
 722
 723 static void drm_dp_crc_sideband_chunk_req(u8 *msg, u8 len)
 724 {
 725         u8 crc4;
 726
 727         crc4 = drm_dp_msg_data_crc4(msg, len);
 728         msg[len] = crc4;
 729 }
 730
 731 static void drm_dp_encode_sideband_reply(struct drm_dp_sideband_msg_reply_body *rep,
 732                                          struct drm_dp_sideband_msg_tx *raw)
 733 {
 734         int idx = 0;
 735         u8 *buf = raw->msg;
 736
 737         buf[idx++] = (rep->reply_type & 0x1) << 7 | (rep->req_type & 0x7f);
 738
 739         raw->cur_len = idx;
 740 }
 741
 742 static int drm_dp_sideband_msg_set_header(struct drm_dp_sideband_msg_rx *msg,
 743                                           struct drm_dp_sideband_msg_hdr *hdr,
 744                                           u8 hdrlen)
 745 {
 746         /*
 747          * ignore out-of-order messages or messages that are part of a
 748          * failed transaction
 749          */
 750         if (!hdr->somt && !msg->have_somt)
 751                 return false;
 752
 753         /* get length contained in this portion */
 754         msg->curchunk_idx = 0;
 755         msg->curchunk_len = hdr->msg_len;
 756         msg->curchunk_hdrlen = hdrlen;
 757
 758         /* we have already gotten an somt - don't bother parsing */
 759         if (hdr->somt && msg->have_somt)
 760                 return false;
 761
 762         if (hdr->somt) {
 763                 memcpy(&msg->initial_hdr, hdr,
 764                        sizeof(struct drm_dp_sideband_msg_hdr));
 765                 msg->have_somt = true;
 766         }
 767         if (hdr->eomt)
 768                 msg->have_eomt = true;
 769
 770         return true;
 771 }
 772
 773 /* this adds a chunk of msg to the builder to get the final msg */
 774 static bool drm_dp_sideband_append_payload(struct drm_dp_sideband_msg_rx *msg,
 775                                            u8 *replybuf, u8 replybuflen)
 776 {
 777         u8 crc4;
 778
 779         memcpy(&msg->chunk[msg->curchunk_idx], replybuf, replybuflen);
 780         msg->curchunk_idx += replybuflen;
 781
 782         if (msg->curchunk_idx >= msg->curchunk_len) {
 783                 /* do CRC */
 784                 crc4 = drm_dp_msg_data_crc4(msg->chunk, msg->curchunk_len - 1);
 785                 if (crc4 != msg->chunk[msg->curchunk_len - 1])
 786                         print_hex_dump(KERN_DEBUG, "wrong crc",
 787                                        DUMP_PREFIX_NONE, 16, 1,
 788                                        msg->chunk,  msg->curchunk_len, false);
 789                 /* copy chunk into bigger msg */
 790                 memcpy(&msg->msg[msg->curlen], msg->chunk, msg->curchunk_len - 1);
 791                 msg->curlen += msg->curchunk_len - 1;
 792         }
 793         return true;
 794 }
 795
 796 static bool drm_dp_sideband_parse_link_address(const struct drm_dp_mst_topology_mgr *mgr,
 797                                                struct drm_dp_sideband_msg_rx *raw,
 798                                                struct drm_dp_sideband_msg_reply_body *repmsg)
 799 {
 800         int idx = 1;
 801         int i;
 802
 803         memcpy(repmsg->u.link_addr.guid, &raw->msg[idx], 16);
 804         idx += 16;
 805         repmsg->u.link_addr.nports = raw->msg[idx] & 0xf;
 806         idx++;
 807         if (idx > raw->curlen)
 808                 goto fail_len;
 809         for (i = 0; i < repmsg->u.link_addr.nports; i++) {
 810                 if (raw->msg[idx] & 0x80)
 811                         repmsg->u.link_addr.ports[i].input_port = 1;
 812
 813                 repmsg->u.link_addr.ports[i].peer_device_type = (raw->msg[idx] >> 4) & 0x7;
 814                 repmsg->u.link_addr.ports[i].port_number = (raw->msg[idx] & 0xf);
 815
 816                 idx++;
 817                 if (idx > raw->curlen)
 818                         goto fail_len;
 819                 repmsg->u.link_addr.ports[i].mcs = (raw->msg[idx] >> 7) & 0x1;
 820                 repmsg->u.link_addr.ports[i].ddps = (raw->msg[idx] >> 6) & 0x1;
 821                 if (repmsg->u.link_addr.ports[i].input_port == 0)
 822                         repmsg->u.link_addr.ports[i].legacy_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
 823                 idx++;
 824                 if (idx > raw->curlen)
 825                         goto fail_len;
 826                 if (repmsg->u.link_addr.ports[i].input_port == 0) {
 827                         repmsg->u.link_addr.ports[i].dpcd_revision = (raw->msg[idx]);
 828                         idx++;
 829                         if (idx > raw->curlen)
 830                                 goto fail_len;
 831                         memcpy(repmsg->u.link_addr.ports[i].peer_guid, &raw->msg[idx], 16);
 832                         idx += 16;
 833                         if (idx > raw->curlen)
 834                                 goto fail_len;
 835                         repmsg->u.link_addr.ports[i].num_sdp_streams = (raw->msg[idx] >> 4) & 0xf;
 836                         repmsg->u.link_addr.ports[i].num_sdp_stream_sinks = (raw->msg[idx] & 0xf);
 837                         idx++;
 838
 839                 }
 840                 if (idx > raw->curlen)
 841                         goto fail_len;
 842         }
 843
 844         return true;
 845 fail_len:
 846         DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
 847         return false;
 848 }
 849
 850 static bool drm_dp_sideband_parse_remote_dpcd_read(struct drm_dp_sideband_msg_rx *raw,
 851                                                    struct drm_dp_sideband_msg_reply_body *repmsg)
 852 {
 853         int idx = 1;
 854
 855         repmsg->u.remote_dpcd_read_ack.port_number = raw->msg[idx] & 0xf;
 856         idx++;
 857         if (idx > raw->curlen)
 858                 goto fail_len;
 859         repmsg->u.remote_dpcd_read_ack.num_bytes = raw->msg[idx];
 860         idx++;
 861         if (idx > raw->curlen)
 862                 goto fail_len;
 863
 864         memcpy(repmsg->u.remote_dpcd_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_dpcd_read_ack.num_bytes);
 865         return true;
 866 fail_len:
 867         DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
 868         return false;
 869 }
 870
 871 static bool drm_dp_sideband_parse_remote_dpcd_write(struct drm_dp_sideband_msg_rx *raw,
 872                                                       struct drm_dp_sideband_msg_reply_body *repmsg)
 873 {
 874         int idx = 1;
 875
 876         repmsg->u.remote_dpcd_write_ack.port_number = raw->msg[idx] & 0xf;
 877         idx++;
 878         if (idx > raw->curlen)
 879                 goto fail_len;
 880         return true;
 881 fail_len:
 882         DRM_DEBUG_KMS("parse length fail %d %d\n", idx, raw->curlen);
 883         return false;
 884 }
 885
 886 static bool drm_dp_sideband_parse_remote_i2c_read_ack(struct drm_dp_sideband_msg_rx *raw,
 887                                                       struct drm_dp_sideband_msg_reply_body *repmsg)
 888 {
 889         int idx = 1;
 890
 891         repmsg->u.remote_i2c_read_ack.port_number = (raw->msg[idx] & 0xf);
 892         idx++;
 893         if (idx > raw->curlen)
 894                 goto fail_len;
 895         repmsg->u.remote_i2c_read_ack.num_bytes = raw->msg[idx];
 896         idx++;
 897         /* TODO check */
 898         memcpy(repmsg->u.remote_i2c_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_i2c_read_ack.num_bytes);
 899         return true;
 900 fail_len:
 901         DRM_DEBUG_KMS("remote i2c reply parse length fail %d %d\n", idx, raw->curlen);
 902         return false;
 903 }
 904
 905 static bool drm_dp_sideband_parse_enum_path_resources_ack(struct drm_dp_sideband_msg_rx *raw,
 906                                                           struct drm_dp_sideband_msg_reply_body *repmsg)
 907 {
 908         int idx = 1;
 909
 910         repmsg->u.path_resources.port_number = (raw->msg[idx] >> 4) & 0xf;
 911         repmsg->u.path_resources.fec_capable = raw->msg[idx] & 0x1;
 912         idx++;
 913         if (idx > raw->curlen)
 914                 goto fail_len;
 915         repmsg->u.path_resources.full_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
 916         idx += 2;
 917         if (idx > raw->curlen)
 918                 goto fail_len;
 919         repmsg->u.path_resources.avail_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
 920         idx += 2;
 921         if (idx > raw->curlen)
 922                 goto fail_len;
 923         return true;
 924 fail_len:
 925         DRM_DEBUG_KMS("enum resource parse length fail %d %d\n", idx, raw->curlen);
 926         return false;
 927 }
 928
 929 static bool drm_dp_sideband_parse_allocate_payload_ack(struct drm_dp_sideband_msg_rx *raw,
 930                                                           struct drm_dp_sideband_msg_reply_body *repmsg)
 931 {
 932         int idx = 1;
 933
 934         repmsg->u.allocate_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
 935         idx++;
 936         if (idx > raw->curlen)
 937                 goto fail_len;
 938         repmsg->u.allocate_payload.vcpi = raw->msg[idx];
 939         idx++;
 940         if (idx > raw->curlen)
 941                 goto fail_len;
 942         repmsg->u.allocate_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
 943         idx += 2;
 944         if (idx > raw->curlen)
 945                 goto fail_len;
 946         return true;
 947 fail_len:
 948         DRM_DEBUG_KMS("allocate payload parse length fail %d %d\n", idx, raw->curlen);
 949         return false;
 950 }
 951
 952 static bool drm_dp_sideband_parse_query_payload_ack(struct drm_dp_sideband_msg_rx *raw,
 953                                                     struct drm_dp_sideband_msg_reply_body *repmsg)
 954 {
 955         int idx = 1;
 956
 957         repmsg->u.query_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
 958         idx++;
 959         if (idx > raw->curlen)
 960                 goto fail_len;
 961         repmsg->u.query_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
 962         idx += 2;
 963         if (idx > raw->curlen)
 964                 goto fail_len;
 965         return true;
 966 fail_len:
 967         DRM_DEBUG_KMS("query payload parse length fail %d %d\n", idx, raw->curlen);
 968         return false;
 969 }
 970
 971 static bool drm_dp_sideband_parse_power_updown_phy_ack(struct drm_dp_sideband_msg_rx *raw,
 972                                                        struct drm_dp_sideband_msg_reply_body *repmsg)
 973 {
 974         int idx = 1;
 975
 976         repmsg->u.port_number.port_number = (raw->msg[idx] >> 4) & 0xf;
 977         idx++;
 978         if (idx > raw->curlen) {
 979                 DRM_DEBUG_KMS("power up/down phy parse length fail %d %d\n",
 980                               idx, raw->curlen);
 981                 return false;
 982         }
 983         return true;
 984 }
 985
 986 static bool
 987 drm_dp_sideband_parse_query_stream_enc_status(
 988                                 struct drm_dp_sideband_msg_rx *raw,
 989                                 struct drm_dp_sideband_msg_reply_body *repmsg)
 990 {
 991         struct drm_dp_query_stream_enc_status_ack_reply *reply;
 992
 993         reply = &repmsg->u.enc_status;
 994
 995         reply->stream_id = raw->msg[3];
 996
 997         reply->reply_signed = raw->msg[2] & BIT(0);
 998
 999         /*
1000          * NOTE: It's my impression from reading the spec that the below parsing
1001          * is correct. However I noticed while testing with an HDCP 1.4 display
1002          * through an HDCP 2.2 hub that only bit 3 was set. In that case, I
1003          * would expect both bits to be set. So keep the parsing following the
1004          * spec, but beware reality might not match the spec (at least for some
1005          * configurations).
1006          */
1007         reply->hdcp_1x_device_present = raw->msg[2] & BIT(4);
1008         reply->hdcp_2x_device_present = raw->msg[2] & BIT(3);
1009
1010         reply->query_capable_device_present = raw->msg[2] & BIT(5);
1011         reply->legacy_device_present = raw->msg[2] & BIT(6);
1012         reply->unauthorizable_device_present = raw->msg[2] & BIT(7);
1013
1014         reply->auth_completed = !!(raw->msg[1] & BIT(3));
1015         reply->encryption_enabled = !!(raw->msg[1] & BIT(4));
1016         reply->repeater_present = !!(raw->msg[1] & BIT(5));
1017         reply->state = (raw->msg[1] & GENMASK(7, 6)) >> 6;
1018
1019         return true;
1020 }
1021
1022 static bool drm_dp_sideband_parse_reply(const struct drm_dp_mst_topology_mgr *mgr,
1023                                         struct drm_dp_sideband_msg_rx *raw,
1024                                         struct drm_dp_sideband_msg_reply_body *msg)
1025 {
1026         memset(msg, 0, sizeof(*msg));
1027         msg->reply_type = (raw->msg[0] & 0x80) >> 7;
1028         msg->req_type = (raw->msg[0] & 0x7f);
1029
1030         if (msg->reply_type == DP_SIDEBAND_REPLY_NAK) {
1031                 memcpy(msg->u.nak.guid, &raw->msg[1], 16);
1032                 msg->u.nak.reason = raw->msg[17];
1033                 msg->u.nak.nak_data = raw->msg[18];
1034                 return false;
1035         }
1036
1037         switch (msg->req_type) {
1038         case DP_LINK_ADDRESS:
1039                 return drm_dp_sideband_parse_link_address(mgr, raw, msg);
1040         case DP_QUERY_PAYLOAD:
1041                 return drm_dp_sideband_parse_query_payload_ack(raw, msg);
1042         case DP_REMOTE_DPCD_READ:
1043                 return drm_dp_sideband_parse_remote_dpcd_read(raw, msg);
1044         case DP_REMOTE_DPCD_WRITE:
1045                 return drm_dp_sideband_parse_remote_dpcd_write(raw, msg);
1046         case DP_REMOTE_I2C_READ:
1047                 return drm_dp_sideband_parse_remote_i2c_read_ack(raw, msg);
1048         case DP_REMOTE_I2C_WRITE:
1049                 return true; /* since there's nothing to parse */
1050         case DP_ENUM_PATH_RESOURCES:
1051                 return drm_dp_sideband_parse_enum_path_resources_ack(raw, msg);
1052         case DP_ALLOCATE_PAYLOAD:
1053                 return drm_dp_sideband_parse_allocate_payload_ack(raw, msg);
1054         case DP_POWER_DOWN_PHY:
1055         case DP_POWER_UP_PHY:
1056                 return drm_dp_sideband_parse_power_updown_phy_ack(raw, msg);
1057         case DP_CLEAR_PAYLOAD_ID_TABLE:
1058                 return true; /* since there's nothing to parse */
1059         case DP_QUERY_STREAM_ENC_STATUS:
1060                 return drm_dp_sideband_parse_query_stream_enc_status(raw, msg);
1061         default:
1062                 drm_err(mgr->dev, "Got unknown reply 0x%02x (%s)\n",
1063                         msg->req_type, drm_dp_mst_req_type_str(msg->req_type));
1064                 return false;
1065         }
1066 }
1067
1068 static bool
1069 drm_dp_sideband_parse_connection_status_notify(const struct drm_dp_mst_topology_mgr *mgr,
1070                                                struct drm_dp_sideband_msg_rx *raw,
1071                                                struct drm_dp_sideband_msg_req_body *msg)
1072 {
1073         int idx = 1;
1074
1075         msg->u.conn_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
1076         idx++;
1077         if (idx > raw->curlen)
1078                 goto fail_len;
1079
1080         memcpy(msg->u.conn_stat.guid, &raw->msg[idx], 16);
1081         idx += 16;
1082         if (idx > raw->curlen)
1083                 goto fail_len;
1084
1085         msg->u.conn_stat.legacy_device_plug_status = (raw->msg[idx] >> 6) & 0x1;
1086         msg->u.conn_stat.displayport_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
1087         msg->u.conn_stat.message_capability_status = (raw->msg[idx] >> 4) & 0x1;
1088         msg->u.conn_stat.input_port = (raw->msg[idx] >> 3) & 0x1;
1089         msg->u.conn_stat.peer_device_type = (raw->msg[idx] & 0x7);
1090         idx++;
1091         return true;
1092 fail_len:
1093         drm_dbg_kms(mgr->dev, "connection status reply parse length fail %d %d\n",
1094                     idx, raw->curlen);
1095         return false;
1096 }
1097
1098 static bool drm_dp_sideband_parse_resource_status_notify(const struct drm_dp_mst_topology_mgr *mgr,
1099                                                          struct drm_dp_sideband_msg_rx *raw,
1100                                                          struct drm_dp_sideband_msg_req_body *msg)
1101 {
1102         int idx = 1;
1103
1104         msg->u.resource_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
1105         idx++;
1106         if (idx > raw->curlen)
1107                 goto fail_len;
1108
1109         memcpy(msg->u.resource_stat.guid, &raw->msg[idx], 16);
1110         idx += 16;
1111         if (idx > raw->curlen)
1112                 goto fail_len;
1113
1114         msg->u.resource_stat.available_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
1115         idx++;
1116         return true;
1117 fail_len:
1118         drm_dbg_kms(mgr->dev, "resource status reply parse length fail %d %d\n", idx, raw->curlen);
1119         return false;
1120 }
1121
1122 static bool drm_dp_sideband_parse_req(const struct drm_dp_mst_topology_mgr *mgr,
1123                                       struct drm_dp_sideband_msg_rx *raw,
1124                                       struct drm_dp_sideband_msg_req_body *msg)
1125 {
1126         memset(msg, 0, sizeof(*msg));
1127         msg->req_type = (raw->msg[0] & 0x7f);
1128
1129         switch (msg->req_type) {
1130         case DP_CONNECTION_STATUS_NOTIFY:
1131                 return drm_dp_sideband_parse_connection_status_notify(mgr, raw, msg);
1132         case DP_RESOURCE_STATUS_NOTIFY:
1133                 return drm_dp_sideband_parse_resource_status_notify(mgr, raw, msg);
1134         default:
1135                 drm_err(mgr->dev, "Got unknown request 0x%02x (%s)\n",
1136                         msg->req_type, drm_dp_mst_req_type_str(msg->req_type));
1137                 return false;
1138         }
1139 }
1140
1141 static void build_dpcd_write(struct drm_dp_sideband_msg_tx *msg,
1142                              u8 port_num, u32 offset, u8 num_bytes, u8 *bytes)
1143 {
1144         struct drm_dp_sideband_msg_req_body req;
1145
1146         req.req_type = DP_REMOTE_DPCD_WRITE;
1147         req.u.dpcd_write.port_number = port_num;
1148         req.u.dpcd_write.dpcd_address = offset;
1149         req.u.dpcd_write.num_bytes = num_bytes;
1150         req.u.dpcd_write.bytes = bytes;
1151         drm_dp_encode_sideband_req(&req, msg);
1152 }
1153
1154 static void build_link_address(struct drm_dp_sideband_msg_tx *msg)
1155 {
1156         struct drm_dp_sideband_msg_req_body req;
1157
1158         req.req_type = DP_LINK_ADDRESS;
1159         drm_dp_encode_sideband_req(&req, msg);
1160 }
1161
1162 static void build_clear_payload_id_table(struct drm_dp_sideband_msg_tx *msg)
1163 {
1164         struct drm_dp_sideband_msg_req_body req;
1165
1166         req.req_type = DP_CLEAR_PAYLOAD_ID_TABLE;
1167         drm_dp_encode_sideband_req(&req, msg);
1168         msg->path_msg = true;
1169 }
1170
1171 static int build_enum_path_resources(struct drm_dp_sideband_msg_tx *msg,
1172                                      int port_num)
1173 {
1174         struct drm_dp_sideband_msg_req_body req;
1175
1176         req.req_type = DP_ENUM_PATH_RESOURCES;
1177         req.u.port_num.port_number = port_num;
1178         drm_dp_encode_sideband_req(&req, msg);
1179         msg->path_msg = true;
1180         return 0;
1181 }
1182
1183 static void build_allocate_payload(struct drm_dp_sideband_msg_tx *msg,
1184                                    int port_num,
1185                                    u8 vcpi, uint16_t pbn,
1186                                    u8 number_sdp_streams,
1187                                    u8 *sdp_stream_sink)
1188 {
1189         struct drm_dp_sideband_msg_req_body req;
1190
1191         memset(&req, 0, sizeof(req));
1192         req.req_type = DP_ALLOCATE_PAYLOAD;
1193         req.u.allocate_payload.port_number = port_num;
1194         req.u.allocate_payload.vcpi = vcpi;
1195         req.u.allocate_payload.pbn = pbn;
1196         req.u.allocate_payload.number_sdp_streams = number_sdp_streams;
1197         memcpy(req.u.allocate_payload.sdp_stream_sink, sdp_stream_sink,
1198                    number_sdp_streams);
1199         drm_dp_encode_sideband_req(&req, msg);
1200         msg->path_msg = true;
1201 }
1202
1203 static void build_power_updown_phy(struct drm_dp_sideband_msg_tx *msg,
1204                                    int port_num, bool power_up)
1205 {
1206         struct drm_dp_sideband_msg_req_body req;
1207
1208         if (power_up)
1209                 req.req_type = DP_POWER_UP_PHY;
1210         else
1211                 req.req_type = DP_POWER_DOWN_PHY;
1212
1213         req.u.port_num.port_number = port_num;
1214         drm_dp_encode_sideband_req(&req, msg);
1215         msg->path_msg = true;
1216 }
1217
1218 static int
1219 build_query_stream_enc_status(struct drm_dp_sideband_msg_tx *msg, u8 stream_id,
1220                               u8 *q_id)
1221 {
1222         struct drm_dp_sideband_msg_req_body req;
1223
1224         req.req_type = DP_QUERY_STREAM_ENC_STATUS;
1225         req.u.enc_status.stream_id = stream_id;
1226         memcpy(req.u.enc_status.client_id, q_id,
1227                sizeof(req.u.enc_status.client_id));
1228         req.u.enc_status.stream_event = 0;
1229         req.u.enc_status.valid_stream_event = false;
1230         req.u.enc_status.stream_behavior = 0;
1231         req.u.enc_status.valid_stream_behavior = false;
1232
1233         drm_dp_encode_sideband_req(&req, msg);
1234         return 0;
1235 }
1236
1237 static int drm_dp_mst_assign_payload_id(struct drm_dp_mst_topology_mgr *mgr,
1238                                         struct drm_dp_vcpi *vcpi)
1239 {
1240         int ret, vcpi_ret;
1241
1242         mutex_lock(&mgr->payload_lock);
1243         ret = find_first_zero_bit(&mgr->payload_mask, mgr->max_payloads + 1);
1244         if (ret > mgr->max_payloads) {
1245                 ret = -EINVAL;
1246                 drm_dbg_kms(mgr->dev, "out of payload ids %d\n", ret);
1247                 goto out_unlock;
1248         }
1249
1250         vcpi_ret = find_first_zero_bit(&mgr->vcpi_mask, mgr->max_payloads + 1);
1251         if (vcpi_ret > mgr->max_payloads) {
1252                 ret = -EINVAL;
1253                 drm_dbg_kms(mgr->dev, "out of vcpi ids %d\n", ret);
1254                 goto out_unlock;
1255         }
1256
1257         set_bit(ret, &mgr->payload_mask);
1258         set_bit(vcpi_ret, &mgr->vcpi_mask);
1259         vcpi->vcpi = vcpi_ret + 1;
1260         mgr->proposed_vcpis[ret - 1] = vcpi;
1261 out_unlock:
1262         mutex_unlock(&mgr->payload_lock);
1263         return ret;
1264 }
1265
1266 static void drm_dp_mst_put_payload_id(struct drm_dp_mst_topology_mgr *mgr,
1267                                       int vcpi)
1268 {
1269         int i;
1270
1271         if (vcpi == 0)
1272                 return;
1273
1274         mutex_lock(&mgr->payload_lock);
1275         drm_dbg_kms(mgr->dev, "putting payload %d\n", vcpi);
1276         clear_bit(vcpi - 1, &mgr->vcpi_mask);
1277
1278         for (i = 0; i < mgr->max_payloads; i++) {
1279                 if (mgr->proposed_vcpis[i] &&
1280                     mgr->proposed_vcpis[i]->vcpi == vcpi) {
1281                         mgr->proposed_vcpis[i] = NULL;
1282                         clear_bit(i + 1, &mgr->payload_mask);
1283                 }
1284         }
1285         mutex_unlock(&mgr->payload_lock);
1286 }
1287
1288 static bool check_txmsg_state(struct drm_dp_mst_topology_mgr *mgr,
1289                               struct drm_dp_sideband_msg_tx *txmsg)
1290 {
1291         unsigned int state;
1292
1293         /*
1294          * All updates to txmsg->state are protected by mgr->qlock, and the two
1295          * cases we check here are terminal states. For those the barriers
1296          * provided by the wake_up/wait_event pair are enough.
1297          */
1298         state = READ_ONCE(txmsg->state);
1299         return (state == DRM_DP_SIDEBAND_TX_RX ||
1300                 state == DRM_DP_SIDEBAND_TX_TIMEOUT);
1301 }
1302
1303 static int drm_dp_mst_wait_tx_reply(struct drm_dp_mst_branch *mstb,
1304                                     struct drm_dp_sideband_msg_tx *txmsg)
1305 {
1306         struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
1307         unsigned long wait_timeout = msecs_to_jiffies(4000);
1308         unsigned long wait_expires = jiffies + wait_timeout;
1309         int ret;
1310
1311         for (;;) {
1312                 /*
1313                  * If the driver provides a way for this, change to
1314                  * poll-waiting for the MST reply interrupt if we didn't receive
1315                  * it for 50 msec. This would cater for cases where the HPD
1316                  * pulse signal got lost somewhere, even though the sink raised
1317                  * the corresponding MST interrupt correctly. One example is the
1318                  * Club 3D CAC-1557 TypeC -> DP adapter which for some reason
1319                  * filters out short pulses with a duration less than ~540 usec.
1320                  *
1321                  * The poll period is 50 msec to avoid missing an interrupt
1322                  * after the sink has cleared it (after a 110msec timeout
1323                  * since it raised the interrupt).
1324                  */
1325                 ret = wait_event_timeout(mgr->tx_waitq,
1326                                          check_txmsg_state(mgr, txmsg),
1327                                          mgr->cbs->poll_hpd_irq ?
1328                                                 msecs_to_jiffies(50) :
1329                                                 wait_timeout);
1330
1331                 if (ret || !mgr->cbs->poll_hpd_irq ||
1332                     time_after(jiffies, wait_expires))
1333                         break;
1334
1335                 mgr->cbs->poll_hpd_irq(mgr);
1336         }
1337
1338         mutex_lock(&mgr->qlock);
1339         if (ret > 0) {
1340                 if (txmsg->state == DRM_DP_SIDEBAND_TX_TIMEOUT) {
1341                         ret = -EIO;
1342                         goto out;
1343                 }
1344         } else {
1345                 drm_dbg_kms(mgr->dev, "timedout msg send %p %d %d\n",
1346                             txmsg, txmsg->state, txmsg->seqno);
1347
1348                 /* dump some state */
1349                 ret = -EIO;
1350
1351                 /* remove from q */
1352                 if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED ||
1353                     txmsg->state == DRM_DP_SIDEBAND_TX_START_SEND ||
1354                     txmsg->state == DRM_DP_SIDEBAND_TX_SENT)
1355                         list_del(&txmsg->next);
1356         }
1357 out:
1358         if (unlikely(ret == -EIO) && drm_debug_enabled(DRM_UT_DP)) {
1359                 struct drm_printer p = drm_debug_printer(DBG_PREFIX);
1360
1361                 drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
1362         }
1363         mutex_unlock(&mgr->qlock);
1364
1365         drm_dp_mst_kick_tx(mgr);
1366         return ret;
1367 }
1368
1369 static struct drm_dp_mst_branch *drm_dp_add_mst_branch_device(u8 lct, u8 *rad)
1370 {
1371         struct drm_dp_mst_branch *mstb;
1372
1373         mstb = kzalloc(sizeof(*mstb), GFP_KERNEL);
1374         if (!mstb)
1375                 return NULL;
1376
1377         mstb->lct = lct;
1378         if (lct > 1)
1379                 memcpy(mstb->rad, rad, lct / 2);
1380         INIT_LIST_HEAD(&mstb->ports);
1381         kref_init(&mstb->topology_kref);
1382         kref_init(&mstb->malloc_kref);
1383         return mstb;
1384 }
1385
1386 static void drm_dp_free_mst_branch_device(struct kref *kref)
1387 {
1388         struct drm_dp_mst_branch *mstb =
1389                 container_of(kref, struct drm_dp_mst_branch, malloc_kref);
1390
1391         if (mstb->port_parent)
1392                 drm_dp_mst_put_port_malloc(mstb->port_parent);
1393
1394         kfree(mstb);
1395 }
1396
1397 /**
1398  * DOC: Branch device and port refcounting
1399  *
1400  * Topology refcount overview
1401  * ~~~~~~~~~~~~~~~~~~~~~~~~~~
1402  *
1403  * The refcounting schemes for &struct drm_dp_mst_branch and &struct
1404  * drm_dp_mst_port are somewhat unusual. Both ports and branch devices have
1405  * two different kinds of refcounts: topology refcounts, and malloc refcounts.
1406  *
1407  * Topology refcounts are not exposed to drivers, and are handled internally
1408  * by the DP MST helpers. The helpers use them in order to prevent the
1409  * in-memory topology state from being changed in the middle of critical
1410  * operations like changing the internal state of payload allocations. This
1411  * means each branch and port will be considered to be connected to the rest
1412  * of the topology until its topology refcount reaches zero. Additionally,
1413  * for ports this means that their associated &struct drm_connector will stay
1414  * registered with userspace until the port's refcount reaches 0.
1415  *
1416  * Malloc refcount overview
1417  * ~~~~~~~~~~~~~~~~~~~~~~~~
1418  *
1419  * Malloc references are used to keep a &struct drm_dp_mst_port or &struct
1420  * drm_dp_mst_branch allocated even after all of its topology references have
1421  * been dropped, so that the driver or MST helpers can safely access each
1422  * branch's last known state before it was disconnected from the topology.
1423  * When the malloc refcount of a port or branch reaches 0, the memory
1424  * allocation containing the &struct drm_dp_mst_branch or &struct
1425  * drm_dp_mst_port respectively will be freed.
1426  *
1427  * For &struct drm_dp_mst_branch, malloc refcounts are not currently exposed
1428  * to drivers. As of writing this documentation, there are no drivers that
1429  * have a usecase for accessing &struct drm_dp_mst_branch outside of the MST
1430  * helpers. Exposing this API to drivers in a race-free manner would take more
1431  * tweaking of the refcounting scheme, however patches are welcome provided
1432  * there is a legitimate driver usecase for this.
1433  *
1434  * Refcount relationships in a topology
1435  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1436  *
1437  * Let's take a look at why the relationship between topology and malloc
1438  * refcounts is designed the way it is.
1439  *
1440  * .. kernel-figure:: dp-mst/topology-figure-1.dot
1441  *
1442  *    An example of topology and malloc refs in a DP MST topology with two
1443  *    active payloads. Topology refcount increments are indicated by solid
1444  *    lines, and malloc refcount increments are indicated by dashed lines.
1445  *    Each starts from the branch which incremented the refcount, and ends at
1446  *    the branch to which the refcount belongs to, i.e. the arrow points the
1447  *    same way as the C pointers used to reference a structure.
1448  *
1449  * As you can see in the above figure, every branch increments the topology
1450  * refcount of its children, and increments the malloc refcount of its
1451  * parent. Additionally, every payload increments the malloc refcount of its
1452  * assigned port by 1.
1453  *
1454  * So, what would happen if MSTB #3 from the above figure was unplugged from
1455  * the system, but the driver hadn't yet removed payload #2 from port #3? The
1456  * topology would start to look like the figure below.
1457  *
1458  * .. kernel-figure:: dp-mst/topology-figure-2.dot
1459  *
1460  *    Ports and branch devices which have been released from memory are
1461  *    colored grey, and references which have been removed are colored red.
1462  *
1463  * Whenever a port or branch device's topology refcount reaches zero, it will
1464  * decrement the topology refcounts of all its children, the malloc refcount
1465  * of its parent, and finally its own malloc refcount. For MSTB #4 and port
1466  * #4, this means they both have been disconnected from the topology and freed
1467  * from memory. But, because payload #2 is still holding a reference to port
1468  * #3, port #3 is removed from the topology but its &struct drm_dp_mst_port
1469  * is still accessible from memory. This also means port #3 has not yet
1470  * decremented the malloc refcount of MSTB #3, so its &struct
1471  * drm_dp_mst_branch will also stay allocated in memory until port #3's
1472  * malloc refcount reaches 0.
1473  *
1474  * This relationship is necessary because in order to release payload #2, we
1475  * need to be able to figure out the last relative of port #3 that's still
1476  * connected to the topology. In this case, we would travel up the topology as
1477  * shown below.
1478  *
1479  * .. kernel-figure:: dp-mst/topology-figure-3.dot
1480  *
1481  * And finally, remove payload #2 by communicating with port #2 through
1482  * sideband transactions.
1483  */
1484
1485 /**
1486  * drm_dp_mst_get_mstb_malloc() - Increment the malloc refcount of a branch
1487  * device
1488  * @mstb: The &struct drm_dp_mst_branch to increment the malloc refcount of
1489  *
1490  * Increments &drm_dp_mst_branch.malloc_kref. When
1491  * &drm_dp_mst_branch.malloc_kref reaches 0, the memory allocation for @mstb
1492  * will be released and @mstb may no longer be used.
1493  *
1494  * See also: drm_dp_mst_put_mstb_malloc()
1495  */
1496 static void
1497 drm_dp_mst_get_mstb_malloc(struct drm_dp_mst_branch *mstb)
1498 {
1499         kref_get(&mstb->malloc_kref);
1500         drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->malloc_kref));
1501 }
1502
1503 /**
1504  * drm_dp_mst_put_mstb_malloc() - Decrement the malloc refcount of a branch
1505  * device
1506  * @mstb: The &struct drm_dp_mst_branch to decrement the malloc refcount of
1507  *
1508  * Decrements &drm_dp_mst_branch.malloc_kref. When
1509  * &drm_dp_mst_branch.malloc_kref reaches 0, the memory allocation for @mstb
1510  * will be released and @mstb may no longer be used.
1511  *
1512  * See also: drm_dp_mst_get_mstb_malloc()
1513  */
1514 static void
1515 drm_dp_mst_put_mstb_malloc(struct drm_dp_mst_branch *mstb)
1516 {
1517         drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->malloc_kref) - 1);
1518         kref_put(&mstb->malloc_kref, drm_dp_free_mst_branch_device);
1519 }
1520
1521 static void drm_dp_free_mst_port(struct kref *kref)
1522 {
1523         struct drm_dp_mst_port *port =
1524                 container_of(kref, struct drm_dp_mst_port, malloc_kref);
1525
1526         drm_dp_mst_put_mstb_malloc(port->parent);
1527         kfree(port);
1528 }
1529
1530 /**
1531  * drm_dp_mst_get_port_malloc() - Increment the malloc refcount of an MST port
1532  * @port: The &struct drm_dp_mst_port to increment the malloc refcount of
1533  *
1534  * Increments &drm_dp_mst_port.malloc_kref. When &drm_dp_mst_port.malloc_kref
1535  * reaches 0, the memory allocation for @port will be released and @port may
1536  * no longer be used.
1537  *
1538  * Because @port could potentially be freed at any time by the DP MST helpers
1539  * if &drm_dp_mst_port.malloc_kref reaches 0, including during a call to this
1540  * function, drivers that which to make use of &struct drm_dp_mst_port should
1541  * ensure that they grab at least one main malloc reference to their MST ports
1542  * in &drm_dp_mst_topology_cbs.add_connector. This callback is called before
1543  * there is any chance for &drm_dp_mst_port.malloc_kref to reach 0.
1544  *
1545  * See also: drm_dp_mst_put_port_malloc()
1546  */
1547 void
1548 drm_dp_mst_get_port_malloc(struct drm_dp_mst_port *port)
1549 {
1550         kref_get(&port->malloc_kref);
1551         drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->malloc_kref));
1552 }
1553 EXPORT_SYMBOL(drm_dp_mst_get_port_malloc);
1554
1555 /**
1556  * drm_dp_mst_put_port_malloc() - Decrement the malloc refcount of an MST port
1557  * @port: The &struct drm_dp_mst_port to decrement the malloc refcount of
1558  *
1559  * Decrements &drm_dp_mst_port.malloc_kref. When &drm_dp_mst_port.malloc_kref
1560  * reaches 0, the memory allocation for @port will be released and @port may
1561  * no longer be used.
1562  *
1563  * See also: drm_dp_mst_get_port_malloc()
1564  */
1565 void
1566 drm_dp_mst_put_port_malloc(struct drm_dp_mst_port *port)
1567 {
1568         drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->malloc_kref) - 1);
1569         kref_put(&port->malloc_kref, drm_dp_free_mst_port);
1570 }
1571 EXPORT_SYMBOL(drm_dp_mst_put_port_malloc);
1572
1573 #if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
1574
1575 #define STACK_DEPTH 8
1576
1577 static noinline void
1578 __topology_ref_save(struct drm_dp_mst_topology_mgr *mgr,
1579                     struct drm_dp_mst_topology_ref_history *history,
1580                     enum drm_dp_mst_topology_ref_type type)
1581 {
1582         struct drm_dp_mst_topology_ref_entry *entry = NULL;
1583         depot_stack_handle_t backtrace;
1584         ulong stack_entries[STACK_DEPTH];
1585         uint n;
1586         int i;
1587
1588         n = stack_trace_save(stack_entries, ARRAY_SIZE(stack_entries), 1);
1589         backtrace = stack_depot_save(stack_entries, n, GFP_KERNEL);
1590         if (!backtrace)
1591                 return;
1592
1593         /* Try to find an existing entry for this backtrace */
1594         for (i = 0; i < history->len; i++) {
1595                 if (history->entries[i].backtrace == backtrace) {
1596                         entry = &history->entries[i];
1597                         break;
1598                 }
1599         }
1600
1601         /* Otherwise add one */
1602         if (!entry) {
1603                 struct drm_dp_mst_topology_ref_entry *new;
1604                 int new_len = history->len + 1;
1605
1606                 new = krealloc(history->entries, sizeof(*new) * new_len,
1607                                GFP_KERNEL);
1608                 if (!new)
1609                         return;
1610
1611                 entry = &new[history->len];
1612                 history->len = new_len;
1613                 history->entries = new;
1614
1615                 entry->backtrace = backtrace;
1616                 entry->type = type;
1617                 entry->count = 0;
1618         }
1619         entry->count++;
1620         entry->ts_nsec = ktime_get_ns();
1621 }
1622
1623 static int
1624 topology_ref_history_cmp(const void *a, const void *b)
1625 {
1626         const struct drm_dp_mst_topology_ref_entry *entry_a = a, *entry_b = b;
1627
1628         if (entry_a->ts_nsec > entry_b->ts_nsec)
1629                 return 1;
1630         else if (entry_a->ts_nsec < entry_b->ts_nsec)
1631                 return -1;
1632         else
1633                 return 0;
1634 }
1635
1636 static inline const char *
1637 topology_ref_type_to_str(enum drm_dp_mst_topology_ref_type type)
1638 {
1639         if (type == DRM_DP_MST_TOPOLOGY_REF_GET)
1640                 return "get";
1641         else
1642                 return "put";
1643 }
1644
1645 static void
1646 __dump_topology_ref_history(struct drm_dp_mst_topology_ref_history *history,
1647                             void *ptr, const char *type_str)
1648 {
1649         struct drm_printer p = drm_debug_printer(DBG_PREFIX);
1650         char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
1651         int i;
1652
1653         if (!buf)
1654                 return;
1655
1656         if (!history->len)
1657                 goto out;
1658
1659         /* First, sort the list so that it goes from oldest to newest
1660          * reference entry
1661          */
1662         sort(history->entries, history->len, sizeof(*history->entries),
1663              topology_ref_history_cmp, NULL);
1664
1665         drm_printf(&p, "%s (%p) topology count reached 0, dumping history:\n",
1666                    type_str, ptr);
1667
1668         for (i = 0; i < history->len; i++) {
1669                 const struct drm_dp_mst_topology_ref_entry *entry =
1670                         &history->entries[i];
1671                 u64 ts_nsec = entry->ts_nsec;
1672                 u32 rem_nsec = do_div(ts_nsec, 1000000000);
1673
1674                 stack_depot_snprint(entry->backtrace, buf, PAGE_SIZE, 4);
1675
1676                 drm_printf(&p, "  %d %ss (last at %5llu.%06u):\n%s",
1677                            entry->count,
1678                            topology_ref_type_to_str(entry->type),
1679                            ts_nsec, rem_nsec / 1000, buf);
1680         }
1681
1682         /* Now free the history, since this is the only time we expose it */
1683         kfree(history->entries);
1684 out:
1685         kfree(buf);
1686 }
1687
1688 static __always_inline void
1689 drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb)
1690 {
1691         __dump_topology_ref_history(&mstb->topology_ref_history, mstb,
1692                                     "MSTB");
1693 }
1694
1695 static __always_inline void
1696 drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port)
1697 {
1698         __dump_topology_ref_history(&port->topology_ref_history, port,
1699                                     "Port");
1700 }
1701
1702 static __always_inline void
1703 save_mstb_topology_ref(struct drm_dp_mst_branch *mstb,
1704                        enum drm_dp_mst_topology_ref_type type)
1705 {
1706         __topology_ref_save(mstb->mgr, &mstb->topology_ref_history, type);
1707 }
1708
1709 static __always_inline void
1710 save_port_topology_ref(struct drm_dp_mst_port *port,
1711                        enum drm_dp_mst_topology_ref_type type)
1712 {
1713         __topology_ref_save(port->mgr, &port->topology_ref_history, type);
1714 }
1715
1716 static inline void
1717 topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr)
1718 {
1719         mutex_lock(&mgr->topology_ref_history_lock);
1720 }
1721
1722 static inline void
1723 topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr)
1724 {
1725         mutex_unlock(&mgr->topology_ref_history_lock);
1726 }
1727 #else
1728 static inline void
1729 topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr) {}
1730 static inline void
1731 topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr) {}
1732 static inline void
1733 drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb) {}
1734 static inline void
1735 drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port) {}
1736 #define save_mstb_topology_ref(mstb, type)
1737 #define save_port_topology_ref(port, type)
1738 #endif
1739
1740 static void drm_dp_destroy_mst_branch_device(struct kref *kref)
1741 {
1742         struct drm_dp_mst_branch *mstb =
1743                 container_of(kref, struct drm_dp_mst_branch, topology_kref);
1744         struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
1745
1746         drm_dp_mst_dump_mstb_topology_history(mstb);
1747
1748         INIT_LIST_HEAD(&mstb->destroy_next);
1749
1750         /*
1751          * This can get called under mgr->mutex, so we need to perform the
1752          * actual destruction of the mstb in another worker
1753          */
1754         mutex_lock(&mgr->delayed_destroy_lock);
1755         list_add(&mstb->destroy_next, &mgr->destroy_branch_device_list);
1756         mutex_unlock(&mgr->delayed_destroy_lock);
1757         queue_work(mgr->delayed_destroy_wq, &mgr->delayed_destroy_work);
1758 }
1759
1760 /**
1761  * drm_dp_mst_topology_try_get_mstb() - Increment the topology refcount of a
1762  * branch device unless it's zero
1763  * @mstb: &struct drm_dp_mst_branch to increment the topology refcount of
1764  *
1765  * Attempts to grab a topology reference to @mstb, if it hasn't yet been
1766  * removed from the topology (e.g. &drm_dp_mst_branch.topology_kref has
1767  * reached 0). Holding a topology reference implies that a malloc reference
1768  * will be held to @mstb as long as the user holds the topology reference.
1769  *
1770  * Care should be taken to ensure that the user has at least one malloc
1771  * reference to @mstb. If you already have a topology reference to @mstb, you
1772  * should use drm_dp_mst_topology_get_mstb() instead.
1773  *
1774  * See also:
1775  * drm_dp_mst_topology_get_mstb()
1776  * drm_dp_mst_topology_put_mstb()
1777  *
1778  * Returns:
1779  * * 1: A topology reference was grabbed successfully
1780  * * 0: @port is no longer in the topology, no reference was grabbed
1781  */
1782 static int __must_check
1783 drm_dp_mst_topology_try_get_mstb(struct drm_dp_mst_branch *mstb)
1784 {
1785         int ret;
1786
1787         topology_ref_history_lock(mstb->mgr);
1788         ret = kref_get_unless_zero(&mstb->topology_kref);
1789         if (ret) {
1790                 drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref));
1791                 save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET);
1792         }
1793
1794         topology_ref_history_unlock(mstb->mgr);
1795
1796         return ret;
1797 }
1798
1799 /**
1800  * drm_dp_mst_topology_get_mstb() - Increment the topology refcount of a
1801  * branch device
1802  * @mstb: The &struct drm_dp_mst_branch to increment the topology refcount of
1803  *
1804  * Increments &drm_dp_mst_branch.topology_refcount without checking whether or
1805  * not it's already reached 0. This is only valid to use in scenarios where
1806  * you are already guaranteed to have at least one active topology reference
1807  * to @mstb. Otherwise, drm_dp_mst_topology_try_get_mstb() must be used.
1808  *
1809  * See also:
1810  * drm_dp_mst_topology_try_get_mstb()
1811  * drm_dp_mst_topology_put_mstb()
1812  */
1813 static void drm_dp_mst_topology_get_mstb(struct drm_dp_mst_branch *mstb)
1814 {
1815         topology_ref_history_lock(mstb->mgr);
1816
1817         save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET);
1818         WARN_ON(kref_read(&mstb->topology_kref) == 0);
1819         kref_get(&mstb->topology_kref);
1820         drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref));
1821
1822         topology_ref_history_unlock(mstb->mgr);
1823 }
1824
1825 /**
1826  * drm_dp_mst_topology_put_mstb() - release a topology reference to a branch
1827  * device
1828  * @mstb: The &struct drm_dp_mst_branch to release the topology reference from
1829  *
1830  * Releases a topology reference from @mstb by decrementing
1831  * &drm_dp_mst_branch.topology_kref.
1832  *
1833  * See also:
1834  * drm_dp_mst_topology_try_get_mstb()
1835  * drm_dp_mst_topology_get_mstb()
1836  */
1837 static void
1838 drm_dp_mst_topology_put_mstb(struct drm_dp_mst_branch *mstb)
1839 {
1840         topology_ref_history_lock(mstb->mgr);
1841
1842         drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref) - 1);
1843         save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_PUT);
1844
1845         topology_ref_history_unlock(mstb->mgr);
1846         kref_put(&mstb->topology_kref, drm_dp_destroy_mst_branch_device);
1847 }
1848
1849 static void drm_dp_destroy_port(struct kref *kref)
1850 {
1851         struct drm_dp_mst_port *port =
1852                 container_of(kref, struct drm_dp_mst_port, topology_kref);
1853         struct drm_dp_mst_topology_mgr *mgr = port->mgr;
1854
1855         drm_dp_mst_dump_port_topology_history(port);
1856
1857         /* There's nothing that needs locking to destroy an input port yet */
1858         if (port->input) {
1859                 drm_dp_mst_put_port_malloc(port);
1860                 return;
1861         }
1862
1863         kfree(port->cached_edid);
1864
1865         /*
1866          * we can't destroy the connector here, as we might be holding the
1867          * mode_config.mutex from an EDID retrieval
1868          */
1869         mutex_lock(&mgr->delayed_destroy_lock);
1870         list_add(&port->next, &mgr->destroy_port_list);
1871         mutex_unlock(&mgr->delayed_destroy_lock);
1872         queue_work(mgr->delayed_destroy_wq, &mgr->delayed_destroy_work);
1873 }
1874
1875 /**
1876  * drm_dp_mst_topology_try_get_port() - Increment the topology refcount of a
1877  * port unless it's zero
1878  * @port: &struct drm_dp_mst_port to increment the topology refcount of
1879  *
1880  * Attempts to grab a topology reference to @port, if it hasn't yet been
1881  * removed from the topology (e.g. &drm_dp_mst_port.topology_kref has reached
1882  * 0). Holding a topology reference implies that a malloc reference will be
1883  * held to @port as long as the user holds the topology reference.
1884  *
1885  * Care should be taken to ensure that the user has at least one malloc
1886  * reference to @port. If you already have a topology reference to @port, you
1887  * should use drm_dp_mst_topology_get_port() instead.
1888  *
1889  * See also:
1890  * drm_dp_mst_topology_get_port()
1891  * drm_dp_mst_topology_put_port()
1892  *
1893  * Returns:
1894  * * 1: A topology reference was grabbed successfully
1895  * * 0: @port is no longer in the topology, no reference was grabbed
1896  */
1897 static int __must_check
1898 drm_dp_mst_topology_try_get_port(struct drm_dp_mst_port *port)
1899 {
1900         int ret;
1901
1902         topology_ref_history_lock(port->mgr);
1903         ret = kref_get_unless_zero(&port->topology_kref);
1904         if (ret) {
1905                 drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->topology_kref));
1906                 save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET);
1907         }
1908
1909         topology_ref_history_unlock(port->mgr);
1910         return ret;
1911 }
1912
1913 /**
1914  * drm_dp_mst_topology_get_port() - Increment the topology refcount of a port
1915  * @port: The &struct drm_dp_mst_port to increment the topology refcount of
1916  *
1917  * Increments &drm_dp_mst_port.topology_refcount without checking whether or
1918  * not it's already reached 0. This is only valid to use in scenarios where
1919  * you are already guaranteed to have at least one active topology reference
1920  * to @port. Otherwise, drm_dp_mst_topology_try_get_port() must be used.
1921  *
1922  * See also:
1923  * drm_dp_mst_topology_try_get_port()
1924  * drm_dp_mst_topology_put_port()
1925  */
1926 static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port)
1927 {
1928         topology_ref_history_lock(port->mgr);
1929
1930         WARN_ON(kref_read(&port->topology_kref) == 0);
1931         kref_get(&port->topology_kref);
1932         drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->topology_kref));
1933         save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET);
1934
1935         topology_ref_history_unlock(port->mgr);
1936 }
1937
1938 /**
1939  * drm_dp_mst_topology_put_port() - release a topology reference to a port
1940  * @port: The &struct drm_dp_mst_port to release the topology reference from
1941  *
1942  * Releases a topology reference from @port by decrementing
1943  * &drm_dp_mst_port.topology_kref.
1944  *
1945  * See also:
1946  * drm_dp_mst_topology_try_get_port()
1947  * drm_dp_mst_topology_get_port()
1948  */
1949 static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port)
1950 {
1951         topology_ref_history_lock(port->mgr);
1952
1953         drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->topology_kref) - 1);
1954         save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_PUT);
1955
1956         topology_ref_history_unlock(port->mgr);
1957         kref_put(&port->topology_kref, drm_dp_destroy_port);
1958 }
1959
1960 static struct drm_dp_mst_branch *
1961 drm_dp_mst_topology_get_mstb_validated_locked(struct drm_dp_mst_branch *mstb,
1962                                               struct drm_dp_mst_branch *to_find)
1963 {
1964         struct drm_dp_mst_port *port;
1965         struct drm_dp_mst_branch *rmstb;
1966
1967         if (to_find == mstb)
1968                 return mstb;
1969
1970         list_for_each_entry(port, &mstb->ports, next) {
1971                 if (port->mstb) {
1972                         rmstb = drm_dp_mst_topology_get_mstb_validated_locked(
1973                             port->mstb, to_find);
1974                         if (rmstb)
1975                                 return rmstb;
1976                 }
1977         }
1978         return NULL;
1979 }
1980
1981 static struct drm_dp_mst_branch *
1982 drm_dp_mst_topology_get_mstb_validated(struct drm_dp_mst_topology_mgr *mgr,
1983                                        struct drm_dp_mst_branch *mstb)
1984 {
1985         struct drm_dp_mst_branch *rmstb = NULL;
1986
1987         mutex_lock(&mgr->lock);
1988         if (mgr->mst_primary) {
1989                 rmstb = drm_dp_mst_topology_get_mstb_validated_locked(
1990                     mgr->mst_primary, mstb);
1991
1992                 if (rmstb && !drm_dp_mst_topology_try_get_mstb(rmstb))
1993                         rmstb = NULL;
1994         }
1995         mutex_unlock(&mgr->lock);
1996         return rmstb;
1997 }
1998
1999 static struct drm_dp_mst_port *
2000 drm_dp_mst_topology_get_port_validated_locked(struct drm_dp_mst_branch *mstb,
2001                                               struct drm_dp_mst_port *to_find)
2002 {
2003         struct drm_dp_mst_port *port, *mport;
2004
2005         list_for_each_entry(port, &mstb->ports, next) {
2006                 if (port == to_find)
2007                         return port;
2008
2009                 if (port->mstb) {
2010                         mport = drm_dp_mst_topology_get_port_validated_locked(
2011                             port->mstb, to_find);
2012                         if (mport)
2013                                 return mport;
2014                 }
2015         }
2016         return NULL;
2017 }
2018
2019 static struct drm_dp_mst_port *
2020 drm_dp_mst_topology_get_port_validated(struct drm_dp_mst_topology_mgr *mgr,
2021                                        struct drm_dp_mst_port *port)
2022 {
2023         struct drm_dp_mst_port *rport = NULL;
2024
2025         mutex_lock(&mgr->lock);
2026         if (mgr->mst_primary) {
2027                 rport = drm_dp_mst_topology_get_port_validated_locked(
2028                     mgr->mst_primary, port);
2029
2030                 if (rport && !drm_dp_mst_topology_try_get_port(rport))
2031                         rport = NULL;
2032         }
2033         mutex_unlock(&mgr->lock);
2034         return rport;
2035 }
2036
2037 static struct drm_dp_mst_port *drm_dp_get_port(struct drm_dp_mst_branch *mstb, u8 port_num)
2038 {
2039         struct drm_dp_mst_port *port;
2040         int ret;
2041
2042         list_for_each_entry(port, &mstb->ports, next) {
2043                 if (port->port_num == port_num) {
2044                         ret = drm_dp_mst_topology_try_get_port(port);
2045                         return ret ? port : NULL;
2046                 }
2047         }
2048
2049         return NULL;
2050 }
2051
2052 /*
2053  * calculate a new RAD for this MST branch device
2054  * if parent has an LCT of 2 then it has 1 nibble of RAD,
2055  * if parent has an LCT of 3 then it has 2 nibbles of RAD,
2056  */
2057 static u8 drm_dp_calculate_rad(struct drm_dp_mst_port *port,
2058                                  u8 *rad)
2059 {
2060         int parent_lct = port->parent->lct;
2061         int shift = 4;
2062         int idx = (parent_lct - 1) / 2;
2063
2064         if (parent_lct > 1) {
2065                 memcpy(rad, port->parent->rad, idx + 1);
2066                 shift = (parent_lct % 2) ? 4 : 0;
2067         } else
2068                 rad[0] = 0;
2069
2070         rad[idx] |= port->port_num << shift;
2071         return parent_lct + 1;
2072 }
2073
2074 static bool drm_dp_mst_is_end_device(u8 pdt, bool mcs)
2075 {
2076         switch (pdt) {
2077         case DP_PEER_DEVICE_DP_LEGACY_CONV:
2078         case DP_PEER_DEVICE_SST_SINK:
2079                 return true;
2080         case DP_PEER_DEVICE_MST_BRANCHING:
2081                 /* For sst branch device */
2082                 if (!mcs)
2083                         return true;
2084
2085                 return false;
2086         }
2087         return true;
2088 }
2089
2090 static int
2091 drm_dp_port_set_pdt(struct drm_dp_mst_port *port, u8 new_pdt,
2092                     bool new_mcs)
2093 {
2094         struct drm_dp_mst_topology_mgr *mgr = port->mgr;
2095         struct drm_dp_mst_branch *mstb;
2096         u8 rad[8], lct;
2097         int ret = 0;
2098
2099         if (port->pdt == new_pdt && port->mcs == new_mcs)
2100                 return 0;
2101
2102         /* Teardown the old pdt, if there is one */
2103         if (port->pdt != DP_PEER_DEVICE_NONE) {
2104                 if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
2105                         /*
2106                          * If the new PDT would also have an i2c bus,
2107                          * don't bother with reregistering it
2108                          */
2109                         if (new_pdt != DP_PEER_DEVICE_NONE &&
2110                             drm_dp_mst_is_end_device(new_pdt, new_mcs)) {
2111                                 port->pdt = new_pdt;
2112                                 port->mcs = new_mcs;
2113                                 return 0;
2114                         }
2115
2116                         /* remove i2c over sideband */
2117                         drm_dp_mst_unregister_i2c_bus(port);
2118                 } else {
2119                         mutex_lock(&mgr->lock);
2120                         drm_dp_mst_topology_put_mstb(port->mstb);
2121                         port->mstb = NULL;
2122                         mutex_unlock(&mgr->lock);
2123                 }
2124         }
2125
2126         port->pdt = new_pdt;
2127         port->mcs = new_mcs;
2128
2129         if (port->pdt != DP_PEER_DEVICE_NONE) {
2130                 if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
2131                         /* add i2c over sideband */
2132                         ret = drm_dp_mst_register_i2c_bus(port);
2133                 } else {
2134                         lct = drm_dp_calculate_rad(port, rad);
2135                         mstb = drm_dp_add_mst_branch_device(lct, rad);
2136                         if (!mstb) {
2137                                 ret = -ENOMEM;
2138                                 drm_err(mgr->dev, "Failed to create MSTB for port %p", port);
2139                                 goto out;
2140                         }
2141
2142                         mutex_lock(&mgr->lock);
2143                         port->mstb = mstb;
2144                         mstb->mgr = port->mgr;
2145                         mstb->port_parent = port;
2146
2147                         /*
2148                          * Make sure this port's memory allocation stays
2149                          * around until its child MSTB releases it
2150                          */
2151                         drm_dp_mst_get_port_malloc(port);
2152                         mutex_unlock(&mgr->lock);
2153
2154                         /* And make sure we send a link address for this */
2155                         ret = 1;
2156                 }
2157         }
2158
2159 out:
2160         if (ret < 0)
2161                 port->pdt = DP_PEER_DEVICE_NONE;
2162         return ret;
2163 }
2164
2165 /**
2166  * drm_dp_mst_dpcd_read() - read a series of bytes from the DPCD via sideband
2167  * @aux: Fake sideband AUX CH
2168  * @offset: address of the (first) register to read
2169  * @buffer: buffer to store the register values
2170  * @size: number of bytes in @buffer
2171  *
2172  * Performs the same functionality for remote devices via
2173  * sideband messaging as drm_dp_dpcd_read() does for local
2174  * devices via actual AUX CH.
2175  *
2176  * Return: Number of bytes read, or negative error code on failure.
2177  */
2178 ssize_t drm_dp_mst_dpcd_read(struct drm_dp_aux *aux,
2179                              unsigned int offset, void *buffer, size_t size)
2180 {
2181         struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
2182                                                     aux);
2183
2184         return drm_dp_send_dpcd_read(port->mgr, port,
2185                                      offset, size, buffer);
2186 }
2187
2188 /**
2189  * drm_dp_mst_dpcd_write() - write a series of bytes to the DPCD via sideband
2190  * @aux: Fake sideband AUX CH
2191  * @offset: address of the (first) register to write
2192  * @buffer: buffer containing the values to write
2193  * @size: number of bytes in @buffer
2194  *
2195  * Performs the same functionality for remote devices via
2196  * sideband messaging as drm_dp_dpcd_write() does for local
2197  * devices via actual AUX CH.
2198  *
2199  * Return: number of bytes written on success, negative error code on failure.
2200  */
2201 ssize_t drm_dp_mst_dpcd_write(struct drm_dp_aux *aux,
2202                               unsigned int offset, void *buffer, size_t size)
2203 {
2204         struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
2205                                                     aux);
2206
2207         return drm_dp_send_dpcd_write(port->mgr, port,
2208                                       offset, size, buffer);
2209 }
2210
2211 static int drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, u8 *guid)
2212 {
2213         int ret = 0;
2214
2215         memcpy(mstb->guid, guid, 16);
2216
2217         if (!drm_dp_validate_guid(mstb->mgr, mstb->guid)) {
2218                 if (mstb->port_parent) {
2219                         ret = drm_dp_send_dpcd_write(mstb->mgr,
2220                                                      mstb->port_parent,
2221                                                      DP_GUID, 16, mstb->guid);
2222                 } else {
2223                         ret = drm_dp_dpcd_write(mstb->mgr->aux,
2224                                                 DP_GUID, mstb->guid, 16);
2225                 }
2226         }
2227
2228         if (ret < 16 && ret > 0)
2229                 return -EPROTO;
2230
2231         return ret == 16 ? 0 : ret;
2232 }
2233
2234 static void build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
2235                                 int pnum,
2236                                 char *proppath,
2237                                 size_t proppath_size)
2238 {
2239         int i;
2240         char temp[8];
2241
2242         snprintf(proppath, proppath_size, "mst:%d", mstb->mgr->conn_base_id);
2243         for (i = 0; i < (mstb->lct - 1); i++) {
2244                 int shift = (i % 2) ? 0 : 4;
2245                 int port_num = (mstb->rad[i / 2] >> shift) & 0xf;
2246
2247                 snprintf(temp, sizeof(temp), "-%d", port_num);
2248                 strlcat(proppath, temp, proppath_size);
2249         }
2250         snprintf(temp, sizeof(temp), "-%d", pnum);
2251         strlcat(proppath, temp, proppath_size);
2252 }
2253
2254 /**
2255  * drm_dp_mst_connector_late_register() - Late MST connector registration
2256  * @connector: The MST connector
2257  * @port: The MST port for this connector
2258  *
2259  * Helper to register the remote aux device for this MST port. Drivers should
2260  * call this from their mst connector's late_register hook to enable MST aux
2261  * devices.
2262  *
2263  * Return: 0 on success, negative error code on failure.
2264  */
2265 int drm_dp_mst_connector_late_register(struct drm_connector *connector,
2266                                        struct drm_dp_mst_port *port)
2267 {
2268         drm_dbg_kms(port->mgr->dev, "registering %s remote bus for %s\n",
2269                     port->aux.name, connector->kdev->kobj.name);
2270
2271         port->aux.dev = connector->kdev;
2272         return drm_dp_aux_register_devnode(&port->aux);
2273 }
2274 EXPORT_SYMBOL(drm_dp_mst_connector_late_register);
2275
2276 /**
2277  * drm_dp_mst_connector_early_unregister() - Early MST connector unregistration
2278  * @connector: The MST connector
2279  * @port: The MST port for this connector
2280  *
2281  * Helper to unregister the remote aux device for this MST port, registered by
2282  * drm_dp_mst_connector_late_register(). Drivers should call this from their mst
2283  * connector's early_unregister hook.
2284  */
2285 void drm_dp_mst_connector_early_unregister(struct drm_connector *connector,
2286                                            struct drm_dp_mst_port *port)
2287 {
2288         drm_dbg_kms(port->mgr->dev, "unregistering %s remote bus for %s\n",
2289                     port->aux.name, connector->kdev->kobj.name);
2290         drm_dp_aux_unregister_devnode(&port->aux);
2291 }
2292 EXPORT_SYMBOL(drm_dp_mst_connector_early_unregister);
2293
2294 static void
2295 drm_dp_mst_port_add_connector(struct drm_dp_mst_branch *mstb,
2296                               struct drm_dp_mst_port *port)
2297 {
2298         struct drm_dp_mst_topology_mgr *mgr = port->mgr;
2299         char proppath[255];
2300         int ret;
2301
2302         build_mst_prop_path(mstb, port->port_num, proppath, sizeof(proppath));
2303         port->connector = mgr->cbs->add_connector(mgr, port, proppath);
2304         if (!port->connector) {
2305                 ret = -ENOMEM;
2306                 goto error;
2307         }
2308
2309         if (port->pdt != DP_PEER_DEVICE_NONE &&
2310             drm_dp_mst_is_end_device(port->pdt, port->mcs) &&
2311             port->port_num >= DP_MST_LOGICAL_PORT_0)
2312                 port->cached_edid = drm_get_edid(port->connector,
2313                                                  &port->aux.ddc);
2314
2315         drm_connector_register(port->connector);
2316         return;
2317
2318 error:
2319         drm_err(mgr->dev, "Failed to create connector for port %p: %d\n", port, ret);
2320 }
2321
2322 /*
2323  * Drop a topology reference, and unlink the port from the in-memory topology
2324  * layout
2325  */
2326 static void
2327 drm_dp_mst_topology_unlink_port(struct drm_dp_mst_topology_mgr *mgr,
2328                                 struct drm_dp_mst_port *port)
2329 {
2330         mutex_lock(&mgr->lock);
2331         port->parent->num_ports--;
2332         list_del(&port->next);
2333         mutex_unlock(&mgr->lock);
2334         drm_dp_mst_topology_put_port(port);
2335 }
2336
2337 static struct drm_dp_mst_port *
2338 drm_dp_mst_add_port(struct drm_device *dev,
2339                     struct drm_dp_mst_topology_mgr *mgr,
2340                     struct drm_dp_mst_branch *mstb, u8 port_number)
2341 {
2342         struct drm_dp_mst_port *port = kzalloc(sizeof(*port), GFP_KERNEL);
2343
2344         if (!port)
2345                 return NULL;
2346
2347         kref_init(&port->topology_kref);
2348         kref_init(&port->malloc_kref);
2349         port->parent = mstb;
2350         port->port_num = port_number;
2351         port->mgr = mgr;
2352         port->aux.name = "DPMST";
2353         port->aux.dev = dev->dev;
2354         port->aux.is_remote = true;
2355
2356         /* initialize the MST downstream port's AUX crc work queue */
2357         port->aux.drm_dev = dev;
2358         drm_dp_remote_aux_init(&port->aux);
2359
2360         /*
2361          * Make sure the memory allocation for our parent branch stays
2362          * around until our own memory allocation is released
2363          */
2364         drm_dp_mst_get_mstb_malloc(mstb);
2365
2366         return port;
2367 }
2368
2369 static int
2370 drm_dp_mst_handle_link_address_port(struct drm_dp_mst_branch *mstb,
2371                                     struct drm_device *dev,
2372                                     struct drm_dp_link_addr_reply_port *port_msg)
2373 {
2374         struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
2375         struct drm_dp_mst_port *port;
2376         int old_ddps = 0, ret;
2377         u8 new_pdt = DP_PEER_DEVICE_NONE;
2378         bool new_mcs = 0;
2379         bool created = false, send_link_addr = false, changed = false;
2380
2381         port = drm_dp_get_port(mstb, port_msg->port_number);
2382         if (!port) {
2383                 port = drm_dp_mst_add_port(dev, mgr, mstb,
2384                                            port_msg->port_number);
2385                 if (!port)
2386                         return -ENOMEM;
2387                 created = true;
2388                 changed = true;
2389         } else if (!port->input && port_msg->input_port && port->connector) {
2390                 /* Since port->connector can't be changed here, we create a
2391                  * new port if input_port changes from 0 to 1
2392                  */
2393                 drm_dp_mst_topology_unlink_port(mgr, port);
2394                 drm_dp_mst_topology_put_port(port);
2395                 port = drm_dp_mst_add_port(dev, mgr, mstb,
2396                                            port_msg->port_number);
2397                 if (!port)
2398                         return -ENOMEM;
2399                 changed = true;
2400                 created = true;
2401         } else if (port->input && !port_msg->input_port) {
2402                 changed = true;
2403         } else if (port->connector) {
2404                 /* We're updating a port that's exposed to userspace, so do it
2405                  * under lock
2406                  */
2407                 drm_modeset_lock(&mgr->base.lock, NULL);
2408
2409                 old_ddps = port->ddps;
2410                 changed = port->ddps != port_msg->ddps ||
2411                         (port->ddps &&
2412                          (port->ldps != port_msg->legacy_device_plug_status ||
2413                           port->dpcd_rev != port_msg->dpcd_revision ||
2414                           port->mcs != port_msg->mcs ||
2415                           port->pdt != port_msg->peer_device_type ||
2416                           port->num_sdp_stream_sinks !=
2417                           port_msg->num_sdp_stream_sinks));
2418         }
2419
2420         port->input = port_msg->input_port;
2421         if (!port->input)
2422                 new_pdt = port_msg->peer_device_type;
2423         new_mcs = port_msg->mcs;
2424         port->ddps = port_msg->ddps;
2425         port->ldps = port_msg->legacy_device_plug_status;
2426         port->dpcd_rev = port_msg->dpcd_revision;
2427         port->num_sdp_streams = port_msg->num_sdp_streams;
2428         port->num_sdp_stream_sinks = port_msg->num_sdp_stream_sinks;
2429
2430         /* manage mstb port lists with mgr lock - take a reference
2431            for this list */
2432         if (created) {
2433                 mutex_lock(&mgr->lock);
2434                 drm_dp_mst_topology_get_port(port);
2435                 list_add(&port->next, &mstb->ports);
2436                 mstb->num_ports++;
2437                 mutex_unlock(&mgr->lock);
2438         }
2439
2440         /*
2441          * Reprobe PBN caps on both hotplug, and when re-probing the link
2442          * for our parent mstb
2443          */
2444         if (old_ddps != port->ddps || !created) {
2445                 if (port->ddps && !port->input) {
2446                         ret = drm_dp_send_enum_path_resources(mgr, mstb,
2447                                                               port);
2448                         if (ret == 1)
2449                                 changed = true;
2450                 } else {
2451                         port->full_pbn = 0;
2452                 }
2453         }
2454
2455         ret = drm_dp_port_set_pdt(port, new_pdt, new_mcs);
2456         if (ret == 1) {
2457                 send_link_addr = true;
2458         } else if (ret < 0) {
2459                 drm_err(dev, "Failed to change PDT on port %p: %d\n", port, ret);
2460                 goto fail;
2461         }
2462
2463         /*
2464          * If this port wasn't just created, then we're reprobing because
2465          * we're coming out of suspend. In this case, always resend the link
2466          * address if there's an MSTB on this port
2467          */
2468         if (!created && port->pdt == DP_PEER_DEVICE_MST_BRANCHING &&
2469             port->mcs)
2470                 send_link_addr = true;
2471
2472         if (port->connector)
2473                 drm_modeset_unlock(&mgr->base.lock);
2474         else if (!port->input)
2475                 drm_dp_mst_port_add_connector(mstb, port);
2476
2477         if (send_link_addr && port->mstb) {
2478                 ret = drm_dp_send_link_address(mgr, port->mstb);
2479                 if (ret == 1) /* MSTB below us changed */
2480                         changed = true;
2481                 else if (ret < 0)
2482                         goto fail_put;
2483         }
2484
2485         /* put reference to this port */
2486         drm_dp_mst_topology_put_port(port);
2487         return changed;
2488
2489 fail:
2490         drm_dp_mst_topology_unlink_port(mgr, port);
2491         if (port->connector)
2492                 drm_modeset_unlock(&mgr->base.lock);
2493 fail_put:
2494         drm_dp_mst_topology_put_port(port);
2495         return ret;
2496 }
2497
2498 static void
2499 drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch *mstb,
2500                             struct drm_dp_connection_status_notify *conn_stat)
2501 {
2502         struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
2503         struct drm_dp_mst_port *port;
2504         int old_ddps, ret;
2505         u8 new_pdt;
2506         bool new_mcs;
2507         bool dowork = false, create_connector = false;
2508
2509         port = drm_dp_get_port(mstb, conn_stat->port_number);
2510         if (!port)
2511                 return;
2512
2513         if (port->connector) {
2514                 if (!port->input && conn_stat->input_port) {
2515                         /*
2516                          * We can't remove a connector from an already exposed
2517                          * port, so just throw the port out and make sure we
2518                          * reprobe the link address of it's parent MSTB
2519                          */
2520                         drm_dp_mst_topology_unlink_port(mgr, port);
2521                         mstb->link_address_sent = false;
2522                         dowork = true;
2523                         goto out;
2524                 }
2525
2526                 /* Locking is only needed if the port's exposed to userspace */
2527                 drm_modeset_lock(&mgr->base.lock, NULL);
2528         } else if (port->input && !conn_stat->input_port) {
2529                 create_connector = true;
2530                 /* Reprobe link address so we get num_sdp_streams */
2531                 mstb->link_address_sent = false;
2532                 dowork = true;
2533         }
2534
2535         old_ddps = port->ddps;
2536         port->input = conn_stat->input_port;
2537         port->ldps = conn_stat->legacy_device_plug_status;
2538         port->ddps = conn_stat->displayport_device_plug_status;
2539
2540         if (old_ddps != port->ddps) {
2541                 if (port->ddps && !port->input)
2542                         drm_dp_send_enum_path_resources(mgr, mstb, port);
2543                 else
2544                         port->full_pbn = 0;
2545         }
2546
2547         new_pdt = port->input ? DP_PEER_DEVICE_NONE : conn_stat->peer_device_type;
2548         new_mcs = conn_stat->message_capability_status;
2549         ret = drm_dp_port_set_pdt(port, new_pdt, new_mcs);
2550         if (ret == 1) {
2551                 dowork = true;
2552         } else if (ret < 0) {
2553                 drm_err(mgr->dev, "Failed to change PDT for port %p: %d\n", port, ret);
2554                 dowork = false;
2555         }
2556
2557         if (port->connector)
2558                 drm_modeset_unlock(&mgr->base.lock);
2559         else if (create_connector)
2560                 drm_dp_mst_port_add_connector(mstb, port);
2561
2562 out:
2563         drm_dp_mst_topology_put_port(port);
2564         if (dowork)
2565                 queue_work(system_long_wq, &mstb->mgr->work);
2566 }
2567
2568 static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_topology_mgr *mgr,
2569                                                                u8 lct, u8 *rad)
2570 {
2571         struct drm_dp_mst_branch *mstb;
2572         struct drm_dp_mst_port *port;
2573         int i, ret;
2574         /* find the port by iterating down */
2575
2576         mutex_lock(&mgr->lock);
2577         mstb = mgr->mst_primary;
2578
2579         if (!mstb)
2580                 goto out;
2581
2582         for (i = 0; i < lct - 1; i++) {
2583                 int shift = (i % 2) ? 0 : 4;
2584                 int port_num = (rad[i / 2] >> shift) & 0xf;
2585
2586                 list_for_each_entry(port, &mstb->ports, next) {
2587                         if (port->port_num == port_num) {
2588                                 mstb = port->mstb;
2589                                 if (!mstb) {
2590                                         drm_err(mgr->dev,
2591                                                 "failed to lookup MSTB with lct %d, rad %02x\n",
2592                                                 lct, rad[0]);
2593                                         goto out;
2594                                 }
2595
2596                                 break;
2597                         }
2598                 }
2599         }
2600         ret = drm_dp_mst_topology_try_get_mstb(mstb);
2601         if (!ret)
2602                 mstb = NULL;
2603 out:
2604         mutex_unlock(&mgr->lock);
2605         return mstb;
2606 }
2607
2608 static struct drm_dp_mst_branch *get_mst_branch_device_by_guid_helper(
2609         struct drm_dp_mst_branch *mstb,
2610         const uint8_t *guid)
2611 {
2612         struct drm_dp_mst_branch *found_mstb;
2613         struct drm_dp_mst_port *port;
2614
2615         if (memcmp(mstb->guid, guid, 16) == 0)
2616                 return mstb;
2617
2618
2619         list_for_each_entry(port, &mstb->ports, next) {
2620                 if (!port->mstb)
2621                         continue;
2622
2623                 found_mstb = get_mst_branch_device_by_guid_helper(port->mstb, guid);
2624
2625                 if (found_mstb)
2626                         return found_mstb;
2627         }
2628
2629         return NULL;
2630 }
2631
2632 static struct drm_dp_mst_branch *
2633 drm_dp_get_mst_branch_device_by_guid(struct drm_dp_mst_topology_mgr *mgr,
2634                                      const uint8_t *guid)
2635 {
2636         struct drm_dp_mst_branch *mstb;
2637         int ret;
2638
2639         /* find the port by iterating down */
2640         mutex_lock(&mgr->lock);
2641
2642         mstb = get_mst_branch_device_by_guid_helper(mgr->mst_primary, guid);
2643         if (mstb) {
2644                 ret = drm_dp_mst_topology_try_get_mstb(mstb);
2645                 if (!ret)
2646                         mstb = NULL;
2647         }
2648
2649         mutex_unlock(&mgr->lock);
2650         return mstb;
2651 }
2652
2653 static int drm_dp_check_and_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
2654                                                struct drm_dp_mst_branch *mstb)
2655 {
2656         struct drm_dp_mst_port *port;
2657         int ret;
2658         bool changed = false;
2659
2660         if (!mstb->link_address_sent) {
2661                 ret = drm_dp_send_link_address(mgr, mstb);
2662                 if (ret == 1)
2663                         changed = true;
2664                 else if (ret < 0)
2665                         return ret;
2666         }
2667
2668         list_for_each_entry(port, &mstb->ports, next) {
2669                 struct drm_dp_mst_branch *mstb_child = NULL;
2670
2671                 if (port->input || !port->ddps)
2672                         continue;
2673
2674                 if (port->mstb)
2675                         mstb_child = drm_dp_mst_topology_get_mstb_validated(
2676                             mgr, port->mstb);
2677
2678                 if (mstb_child) {
2679                         ret = drm_dp_check_and_send_link_address(mgr,
2680                                                                  mstb_child);
2681                         drm_dp_mst_topology_put_mstb(mstb_child);
2682                         if (ret == 1)
2683                                 changed = true;
2684                         else if (ret < 0)
2685                                 return ret;
2686                 }
2687         }
2688
2689         return changed;
2690 }
2691
2692 static void drm_dp_mst_link_probe_work(struct work_struct *work)
2693 {
2694         struct drm_dp_mst_topology_mgr *mgr =
2695                 container_of(work, struct drm_dp_mst_topology_mgr, work);
2696         struct drm_device *dev = mgr->dev;
2697         struct drm_dp_mst_branch *mstb;
2698         int ret;
2699         bool clear_payload_id_table;
2700
2701         mutex_lock(&mgr->probe_lock);
2702
2703         mutex_lock(&mgr->lock);
2704         clear_payload_id_table = !mgr->payload_id_table_cleared;
2705         mgr->payload_id_table_cleared = true;
2706
2707         mstb = mgr->mst_primary;
2708         if (mstb) {
2709                 ret = drm_dp_mst_topology_try_get_mstb(mstb);
2710                 if (!ret)
2711                         mstb = NULL;
2712         }
2713         mutex_unlock(&mgr->lock);
2714         if (!mstb) {
2715                 mutex_unlock(&mgr->probe_lock);
2716                 return;
2717         }
2718
2719         /*
2720          * Certain branch devices seem to incorrectly report an available_pbn
2721          * of 0 on downstream sinks, even after clearing the
2722          * DP_PAYLOAD_ALLOCATE_* registers in
2723          * drm_dp_mst_topology_mgr_set_mst(). Namely, the CableMatters USB-C
2724          * 2x DP hub. Sending a CLEAR_PAYLOAD_ID_TABLE message seems to make
2725          * things work again.
2726          */
2727         if (clear_payload_id_table) {
2728                 drm_dbg_kms(dev, "Clearing payload ID table\n");
2729                 drm_dp_send_clear_payload_id_table(mgr, mstb);
2730         }
2731
2732         ret = drm_dp_check_and_send_link_address(mgr, mstb);
2733         drm_dp_mst_topology_put_mstb(mstb);
2734
2735         mutex_unlock(&mgr->probe_lock);
2736         if (ret > 0)
2737                 drm_kms_helper_hotplug_event(dev);
2738 }
2739
2740 static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
2741                                  u8 *guid)
2742 {
2743         u64 salt;
2744
2745         if (memchr_inv(guid, 0, 16))
2746                 return true;
2747
2748         salt = get_jiffies_64();
2749
2750         memcpy(&guid[0], &salt, sizeof(u64));
2751         memcpy(&guid[8], &salt, sizeof(u64));
2752
2753         return false;
2754 }
2755
2756 static void build_dpcd_read(struct drm_dp_sideband_msg_tx *msg,
2757                             u8 port_num, u32 offset, u8 num_bytes)
2758 {
2759         struct drm_dp_sideband_msg_req_body req;
2760
2761         req.req_type = DP_REMOTE_DPCD_READ;
2762         req.u.dpcd_read.port_number = port_num;
2763         req.u.dpcd_read.dpcd_address = offset;
2764         req.u.dpcd_read.num_bytes = num_bytes;
2765         drm_dp_encode_sideband_req(&req, msg);
2766 }
2767
2768 static int drm_dp_send_sideband_msg(struct drm_dp_mst_topology_mgr *mgr,
2769                                     bool up, u8 *msg, int len)
2770 {
2771         int ret;
2772         int regbase = up ? DP_SIDEBAND_MSG_UP_REP_BASE : DP_SIDEBAND_MSG_DOWN_REQ_BASE;
2773         int tosend, total, offset;
2774         int retries = 0;
2775
2776 retry:
2777         total = len;
2778         offset = 0;
2779         do {
2780                 tosend = min3(mgr->max_dpcd_transaction_bytes, 16, total);
2781
2782                 ret = drm_dp_dpcd_write(mgr->aux, regbase + offset,
2783                                         &msg[offset],
2784                                         tosend);
2785                 if (ret != tosend) {
2786                         if (ret == -EIO && retries < 5) {
2787                                 retries++;
2788                                 goto retry;
2789                         }
2790                         drm_dbg_kms(mgr->dev, "failed to dpcd write %d %d\n", tosend, ret);
2791
2792                         return -EIO;
2793                 }
2794                 offset += tosend;
2795                 total -= tosend;
2796         } while (total > 0);
2797         return 0;
2798 }
2799
2800 static int set_hdr_from_dst_qlock(struct drm_dp_sideband_msg_hdr *hdr,
2801                                   struct drm_dp_sideband_msg_tx *txmsg)
2802 {
2803         struct drm_dp_mst_branch *mstb = txmsg->dst;
2804         u8 req_type;
2805
2806         req_type = txmsg->msg[0] & 0x7f;
2807         if (req_type == DP_CONNECTION_STATUS_NOTIFY ||
2808                 req_type == DP_RESOURCE_STATUS_NOTIFY ||
2809                 req_type == DP_CLEAR_PAYLOAD_ID_TABLE)
2810                 hdr->broadcast = 1;
2811         else
2812                 hdr->broadcast = 0;
2813         hdr->path_msg = txmsg->path_msg;
2814         if (hdr->broadcast) {
2815                 hdr->lct = 1;
2816                 hdr->lcr = 6;
2817         } else {
2818                 hdr->lct = mstb->lct;
2819                 hdr->lcr = mstb->lct - 1;
2820         }
2821
2822         memcpy(hdr->rad, mstb->rad, hdr->lct / 2);
2823
2824         return 0;
2825 }
2826 /*
2827  * process a single block of the next message in the sideband queue
2828  */
2829 static int process_single_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
2830                                    struct drm_dp_sideband_msg_tx *txmsg,
2831                                    bool up)
2832 {
2833         u8 chunk[48];
2834         struct drm_dp_sideband_msg_hdr hdr;
2835         int len, space, idx, tosend;
2836         int ret;
2837
2838         if (txmsg->state == DRM_DP_SIDEBAND_TX_SENT)
2839                 return 0;
2840
2841         memset(&hdr, 0, sizeof(struct drm_dp_sideband_msg_hdr));
2842
2843         if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED)
2844                 txmsg->state = DRM_DP_SIDEBAND_TX_START_SEND;
2845
2846         /* make hdr from dst mst */
2847         ret = set_hdr_from_dst_qlock(&hdr, txmsg);
2848         if (ret < 0)
2849                 return ret;
2850
2851         /* amount left to send in this message */
2852         len = txmsg->cur_len - txmsg->cur_offset;
2853
2854         /* 48 - sideband msg size - 1 byte for data CRC, x header bytes */
2855         space = 48 - 1 - drm_dp_calc_sb_hdr_size(&hdr);
2856
2857         tosend = min(len, space);
2858         if (len == txmsg->cur_len)
2859                 hdr.somt = 1;
2860         if (space >= len)
2861                 hdr.eomt = 1;
2862
2863
2864         hdr.msg_len = tosend + 1;
2865         drm_dp_encode_sideband_msg_hdr(&hdr, chunk, &idx);
2866         memcpy(&chunk[idx], &txmsg->msg[txmsg->cur_offset], tosend);
2867         /* add crc at end */
2868         drm_dp_crc_sideband_chunk_req(&chunk[idx], tosend);
2869         idx += tosend + 1;
2870
2871         ret = drm_dp_send_sideband_msg(mgr, up, chunk, idx);
2872         if (ret) {
2873                 if (drm_debug_enabled(DRM_UT_DP)) {
2874                         struct drm_printer p = drm_debug_printer(DBG_PREFIX);
2875
2876                         drm_printf(&p, "sideband msg failed to send\n");
2877                         drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
2878                 }
2879                 return ret;
2880         }
2881
2882         txmsg->cur_offset += tosend;
2883         if (txmsg->cur_offset == txmsg->cur_len) {
2884                 txmsg->state = DRM_DP_SIDEBAND_TX_SENT;
2885                 return 1;
2886         }
2887         return 0;
2888 }
2889
2890 static void process_single_down_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
2891 {
2892         struct drm_dp_sideband_msg_tx *txmsg;
2893         int ret;
2894
2895         WARN_ON(!mutex_is_locked(&mgr->qlock));
2896
2897         /* construct a chunk from the first msg in the tx_msg queue */
2898         if (list_empty(&mgr->tx_msg_downq))
2899                 return;
2900
2901         txmsg = list_first_entry(&mgr->tx_msg_downq,
2902                                  struct drm_dp_sideband_msg_tx, next);
2903         ret = process_single_tx_qlock(mgr, txmsg, false);
2904         if (ret < 0) {
2905                 drm_dbg_kms(mgr->dev, "failed to send msg in q %d\n", ret);
2906                 list_del(&txmsg->next);
2907                 txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
2908                 wake_up_all(&mgr->tx_waitq);
2909         }
2910 }
2911
2912 static void drm_dp_queue_down_tx(struct drm_dp_mst_topology_mgr *mgr,
2913                                  struct drm_dp_sideband_msg_tx *txmsg)
2914 {
2915         mutex_lock(&mgr->qlock);
2916         list_add_tail(&txmsg->next, &mgr->tx_msg_downq);
2917
2918         if (drm_debug_enabled(DRM_UT_DP)) {
2919                 struct drm_printer p = drm_debug_printer(DBG_PREFIX);
2920
2921                 drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
2922         }
2923
2924         if (list_is_singular(&mgr->tx_msg_downq))
2925                 process_single_down_tx_qlock(mgr);
2926         mutex_unlock(&mgr->qlock);
2927 }
2928
2929 static void
2930 drm_dp_dump_link_address(const struct drm_dp_mst_topology_mgr *mgr,
2931                          struct drm_dp_link_address_ack_reply *reply)
2932 {
2933         struct drm_dp_link_addr_reply_port *port_reply;
2934         int i;
2935
2936         for (i = 0; i < reply->nports; i++) {
2937                 port_reply = &reply->ports[i];
2938                 drm_dbg_kms(mgr->dev,
2939                             "port %d: input %d, pdt: %d, pn: %d, dpcd_rev: %02x, mcs: %d, ddps: %d, ldps %d, sdp %d/%d\n",
2940                             i,
2941                             port_reply->input_port,
2942                             port_reply->peer_device_type,
2943                             port_reply->port_number,
2944                             port_reply->dpcd_revision,
2945                             port_reply->mcs,
2946                             port_reply->ddps,
2947                             port_reply->legacy_device_plug_status,
2948                             port_reply->num_sdp_streams,
2949                             port_reply->num_sdp_stream_sinks);
2950         }
2951 }
2952
2953 static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
2954                                      struct drm_dp_mst_branch *mstb)
2955 {
2956         struct drm_dp_sideband_msg_tx *txmsg;
2957         struct drm_dp_link_address_ack_reply *reply;
2958         struct drm_dp_mst_port *port, *tmp;
2959         int i, ret, port_mask = 0;
2960         bool changed = false;
2961
2962         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
2963         if (!txmsg)
2964                 return -ENOMEM;
2965
2966         txmsg->dst = mstb;
2967         build_link_address(txmsg);
2968
2969         mstb->link_address_sent = true;
2970         drm_dp_queue_down_tx(mgr, txmsg);
2971
2972         /* FIXME: Actually do some real error handling here */
2973         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
2974         if (ret <= 0) {
2975                 drm_err(mgr->dev, "Sending link address failed with %d\n", ret);
2976                 goto out;
2977         }
2978         if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
2979                 drm_err(mgr->dev, "link address NAK received\n");
2980                 ret = -EIO;
2981                 goto out;
2982         }
2983
2984         reply = &txmsg->reply.u.link_addr;
2985         drm_dbg_kms(mgr->dev, "link address reply: %d\n", reply->nports);
2986         drm_dp_dump_link_address(mgr, reply);
2987
2988         ret = drm_dp_check_mstb_guid(mstb, reply->guid);
2989         if (ret) {
2990                 char buf[64];
2991
2992                 drm_dp_mst_rad_to_str(mstb->rad, mstb->lct, buf, sizeof(buf));
2993                 drm_err(mgr->dev, "GUID check on %s failed: %d\n", buf, ret);
2994                 goto out;
2995         }
2996
2997         for (i = 0; i < reply->nports; i++) {
2998                 port_mask |= BIT(reply->ports[i].port_number);
2999                 ret = drm_dp_mst_handle_link_address_port(mstb, mgr->dev,
3000                                                           &reply->ports[i]);
3001                 if (ret == 1)
3002                         changed = true;
3003                 else if (ret < 0)
3004                         goto out;
3005         }
3006
3007         /* Prune any ports that are currently a part of mstb in our in-memory
3008          * topology, but were not seen in this link address. Usually this
3009          * means that they were removed while the topology was out of sync,
3010          * e.g. during suspend/resume
3011          */
3012         mutex_lock(&mgr->lock);
3013         list_for_each_entry_safe(port, tmp, &mstb->ports, next) {
3014                 if (port_mask & BIT(port->port_num))
3015                         continue;
3016
3017                 drm_dbg_kms(mgr->dev, "port %d was not in link address, removing\n",
3018                             port->port_num);
3019                 list_del(&port->next);
3020                 drm_dp_mst_topology_put_port(port);
3021                 changed = true;
3022         }
3023         mutex_unlock(&mgr->lock);
3024
3025 out:
3026         if (ret <= 0)
3027                 mstb->link_address_sent = false;
3028         kfree(txmsg);
3029         return ret < 0 ? ret : changed;
3030 }
3031
3032 static void
3033 drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr,
3034                                    struct drm_dp_mst_branch *mstb)
3035 {
3036         struct drm_dp_sideband_msg_tx *txmsg;
3037         int ret;
3038
3039         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3040         if (!txmsg)
3041                 return;
3042
3043         txmsg->dst = mstb;
3044         build_clear_payload_id_table(txmsg);
3045
3046         drm_dp_queue_down_tx(mgr, txmsg);
3047
3048         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3049         if (ret > 0 && txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3050                 drm_dbg_kms(mgr->dev, "clear payload table id nak received\n");
3051
3052         kfree(txmsg);
3053 }
3054
3055 static int
3056 drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
3057                                 struct drm_dp_mst_branch *mstb,
3058                                 struct drm_dp_mst_port *port)
3059 {
3060         struct drm_dp_enum_path_resources_ack_reply *path_res;
3061         struct drm_dp_sideband_msg_tx *txmsg;
3062         int ret;
3063
3064         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3065         if (!txmsg)
3066                 return -ENOMEM;
3067
3068         txmsg->dst = mstb;
3069         build_enum_path_resources(txmsg, port->port_num);
3070
3071         drm_dp_queue_down_tx(mgr, txmsg);
3072
3073         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3074         if (ret > 0) {
3075                 ret = 0;
3076                 path_res = &txmsg->reply.u.path_resources;
3077
3078                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
3079                         drm_dbg_kms(mgr->dev, "enum path resources nak received\n");
3080                 } else {
3081                         if (port->port_num != path_res->port_number)
3082                                 DRM_ERROR("got incorrect port in response\n");
3083
3084                         drm_dbg_kms(mgr->dev, "enum path resources %d: %d %d\n",
3085                                     path_res->port_number,
3086                                     path_res->full_payload_bw_number,
3087                                     path_res->avail_payload_bw_number);
3088
3089                         /*
3090                          * If something changed, make sure we send a
3091                          * hotplug
3092                          */
3093                         if (port->full_pbn != path_res->full_payload_bw_number ||
3094                             port->fec_capable != path_res->fec_capable)
3095                                 ret = 1;
3096
3097                         port->full_pbn = path_res->full_payload_bw_number;
3098                         port->fec_capable = path_res->fec_capable;
3099                 }
3100         }
3101
3102         kfree(txmsg);
3103         return ret;
3104 }
3105
3106 static struct drm_dp_mst_port *drm_dp_get_last_connected_port_to_mstb(struct drm_dp_mst_branch *mstb)
3107 {
3108         if (!mstb->port_parent)
3109                 return NULL;
3110
3111         if (mstb->port_parent->mstb != mstb)
3112                 return mstb->port_parent;
3113
3114         return drm_dp_get_last_connected_port_to_mstb(mstb->port_parent->parent);
3115 }
3116
3117 /*
3118  * Searches upwards in the topology starting from mstb to try to find the
3119  * closest available parent of mstb that's still connected to the rest of the
3120  * topology. This can be used in order to perform operations like releasing
3121  * payloads, where the branch device which owned the payload may no longer be
3122  * around and thus would require that the payload on the last living relative
3123  * be freed instead.
3124  */
3125 static struct drm_dp_mst_branch *
3126 drm_dp_get_last_connected_port_and_mstb(struct drm_dp_mst_topology_mgr *mgr,
3127                                         struct drm_dp_mst_branch *mstb,
3128                                         int *port_num)
3129 {
3130         struct drm_dp_mst_branch *rmstb = NULL;
3131         struct drm_dp_mst_port *found_port;
3132
3133         mutex_lock(&mgr->lock);
3134         if (!mgr->mst_primary)
3135                 goto out;
3136
3137         do {
3138                 found_port = drm_dp_get_last_connected_port_to_mstb(mstb);
3139                 if (!found_port)
3140                         break;
3141
3142                 if (drm_dp_mst_topology_try_get_mstb(found_port->parent)) {
3143                         rmstb = found_port->parent;
3144                         *port_num = found_port->port_num;
3145                 } else {
3146                         /* Search again, starting from this parent */
3147                         mstb = found_port->parent;
3148                 }
3149         } while (!rmstb);
3150 out:
3151         mutex_unlock(&mgr->lock);
3152         return rmstb;
3153 }
3154
3155 static int drm_dp_payload_send_msg(struct drm_dp_mst_topology_mgr *mgr,
3156                                    struct drm_dp_mst_port *port,
3157                                    int id,
3158                                    int pbn)
3159 {
3160         struct drm_dp_sideband_msg_tx *txmsg;
3161         struct drm_dp_mst_branch *mstb;
3162         int ret, port_num;
3163         u8 sinks[DRM_DP_MAX_SDP_STREAMS];
3164         int i;
3165
3166         port_num = port->port_num;
3167         mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
3168         if (!mstb) {
3169                 mstb = drm_dp_get_last_connected_port_and_mstb(mgr,
3170                                                                port->parent,
3171                                                                &port_num);
3172
3173                 if (!mstb)
3174                         return -EINVAL;
3175         }
3176
3177         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3178         if (!txmsg) {
3179                 ret = -ENOMEM;
3180                 goto fail_put;
3181         }
3182
3183         for (i = 0; i < port->num_sdp_streams; i++)
3184                 sinks[i] = i;
3185
3186         txmsg->dst = mstb;
3187         build_allocate_payload(txmsg, port_num,
3188                                id,
3189                                pbn, port->num_sdp_streams, sinks);
3190
3191         drm_dp_queue_down_tx(mgr, txmsg);
3192
3193         /*
3194          * FIXME: there is a small chance that between getting the last
3195          * connected mstb and sending the payload message, the last connected
3196          * mstb could also be removed from the topology. In the future, this
3197          * needs to be fixed by restarting the
3198          * drm_dp_get_last_connected_port_and_mstb() search in the event of a
3199          * timeout if the topology is still connected to the system.
3200          */
3201         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3202         if (ret > 0) {
3203                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3204                         ret = -EINVAL;
3205                 else
3206                         ret = 0;
3207         }
3208         kfree(txmsg);
3209 fail_put:
3210         drm_dp_mst_topology_put_mstb(mstb);
3211         return ret;
3212 }
3213
3214 int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,
3215                                  struct drm_dp_mst_port *port, bool power_up)
3216 {
3217         struct drm_dp_sideband_msg_tx *txmsg;
3218         int ret;
3219
3220         port = drm_dp_mst_topology_get_port_validated(mgr, port);
3221         if (!port)
3222                 return -EINVAL;
3223
3224         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3225         if (!txmsg) {
3226                 drm_dp_mst_topology_put_port(port);
3227                 return -ENOMEM;
3228         }
3229
3230         txmsg->dst = port->parent;
3231         build_power_updown_phy(txmsg, port->port_num, power_up);
3232         drm_dp_queue_down_tx(mgr, txmsg);
3233
3234         ret = drm_dp_mst_wait_tx_reply(port->parent, txmsg);
3235         if (ret > 0) {
3236                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3237                         ret = -EINVAL;
3238                 else
3239                         ret = 0;
3240         }
3241         kfree(txmsg);
3242         drm_dp_mst_topology_put_port(port);
3243
3244         return ret;
3245 }
3246 EXPORT_SYMBOL(drm_dp_send_power_updown_phy);
3247
3248 int drm_dp_send_query_stream_enc_status(struct drm_dp_mst_topology_mgr *mgr,
3249                 struct drm_dp_mst_port *port,
3250                 struct drm_dp_query_stream_enc_status_ack_reply *status)
3251 {
3252         struct drm_dp_sideband_msg_tx *txmsg;
3253         u8 nonce[7];
3254         int ret;
3255
3256         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3257         if (!txmsg)
3258                 return -ENOMEM;
3259
3260         port = drm_dp_mst_topology_get_port_validated(mgr, port);
3261         if (!port) {
3262                 ret = -EINVAL;
3263                 goto out_get_port;
3264         }
3265
3266         get_random_bytes(nonce, sizeof(nonce));
3267
3268         /*
3269          * "Source device targets the QUERY_STREAM_ENCRYPTION_STATUS message
3270          *  transaction at the MST Branch device directly connected to the
3271          *  Source"
3272          */
3273         txmsg->dst = mgr->mst_primary;
3274
3275         build_query_stream_enc_status(txmsg, port->vcpi.vcpi, nonce);
3276
3277         drm_dp_queue_down_tx(mgr, txmsg);
3278
3279         ret = drm_dp_mst_wait_tx_reply(mgr->mst_primary, txmsg);
3280         if (ret < 0) {
3281                 goto out;
3282         } else if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
3283                 drm_dbg_kms(mgr->dev, "query encryption status nak received\n");
3284                 ret = -ENXIO;
3285                 goto out;
3286         }
3287
3288         ret = 0;
3289         memcpy(status, &txmsg->reply.u.enc_status, sizeof(*status));
3290
3291 out:
3292         drm_dp_mst_topology_put_port(port);
3293 out_get_port:
3294         kfree(txmsg);
3295         return ret;
3296 }
3297 EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
3298
3299 static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
3300                                        int id,
3301                                        struct drm_dp_payload *payload)
3302 {
3303         int ret;
3304
3305         ret = drm_dp_dpcd_write_payload(mgr, id, payload);
3306         if (ret < 0) {
3307                 payload->payload_state = 0;
3308                 return ret;
3309         }
3310         payload->payload_state = DP_PAYLOAD_LOCAL;
3311         return 0;
3312 }
3313
3314 static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
3315                                        struct drm_dp_mst_port *port,
3316                                        int id,
3317                                        struct drm_dp_payload *payload)
3318 {
3319         int ret;
3320
3321         ret = drm_dp_payload_send_msg(mgr, port, id, port->vcpi.pbn);
3322         if (ret < 0)
3323                 return ret;
3324         payload->payload_state = DP_PAYLOAD_REMOTE;
3325         return ret;
3326 }
3327
3328 static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
3329                                         struct drm_dp_mst_port *port,
3330                                         int id,
3331                                         struct drm_dp_payload *payload)
3332 {
3333         drm_dbg_kms(mgr->dev, "\n");
3334         /* it's okay for these to fail */
3335         if (port) {
3336                 drm_dp_payload_send_msg(mgr, port, id, 0);
3337         }
3338
3339         drm_dp_dpcd_write_payload(mgr, id, payload);
3340         payload->payload_state = DP_PAYLOAD_DELETE_LOCAL;
3341         return 0;
3342 }
3343
3344 static int drm_dp_destroy_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
3345                                         int id,
3346                                         struct drm_dp_payload *payload)
3347 {
3348         payload->payload_state = 0;
3349         return 0;
3350 }
3351
3352 /**
3353  * drm_dp_update_payload_part1() - Execute payload update part 1
3354  * @mgr: manager to use.
3355  * @start_slot: this is the cur slot
3356  *
3357  * NOTE: start_slot is a temporary workaround for non-atomic drivers,
3358  * this will be removed when non-atomic mst helpers are moved out of the helper
3359  *
3360  * This iterates over all proposed virtual channels, and tries to
3361  * allocate space in the link for them. For 0->slots transitions,
3362  * this step just writes the VCPI to the MST device. For slots->0
3363  * transitions, this writes the updated VCPIs and removes the
3364  * remote VC payloads.
3365  *
3366  * after calling this the driver should generate ACT and payload
3367  * packets.
3368  */
3369 int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr, int start_slot)
3370 {
3371         struct drm_dp_payload req_payload;
3372         struct drm_dp_mst_port *port;
3373         int i, j;
3374         int cur_slots = start_slot;
3375         bool skip;
3376
3377         mutex_lock(&mgr->payload_lock);
3378         for (i = 0; i < mgr->max_payloads; i++) {
3379                 struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i];
3380                 struct drm_dp_payload *payload = &mgr->payloads[i];
3381                 bool put_port = false;
3382
3383                 /* solve the current payloads - compare to the hw ones
3384                    - update the hw view */
3385                 req_payload.start_slot = cur_slots;
3386                 if (vcpi) {
3387                         port = container_of(vcpi, struct drm_dp_mst_port,
3388                                             vcpi);
3389
3390                         mutex_lock(&mgr->lock);
3391                         skip = !drm_dp_mst_port_downstream_of_branch(port, mgr->mst_primary);
3392                         mutex_unlock(&mgr->lock);
3393
3394                         if (skip) {
3395                                 drm_dbg_kms(mgr->dev,
3396                                             "Virtual channel %d is not in current topology\n",
3397                                             i);
3398                                 continue;
3399                         }
3400                         /* Validated ports don't matter if we're releasing
3401                          * VCPI
3402                          */
3403                         if (vcpi->num_slots) {
3404                                 port = drm_dp_mst_topology_get_port_validated(
3405                                     mgr, port);
3406                                 if (!port) {
3407                                         if (vcpi->num_slots == payload->num_slots) {
3408                                                 cur_slots += vcpi->num_slots;
3409                                                 payload->start_slot = req_payload.start_slot;
3410                                                 continue;
3411                                         } else {
3412                                                 drm_dbg_kms(mgr->dev,
3413                                                             "Fail:set payload to invalid sink");
3414                                                 mutex_unlock(&mgr->payload_lock);
3415                                                 return -EINVAL;
3416                                         }
3417                                 }
3418                                 put_port = true;
3419                         }
3420
3421                         req_payload.num_slots = vcpi->num_slots;
3422                         req_payload.vcpi = vcpi->vcpi;
3423                 } else {
3424                         port = NULL;
3425                         req_payload.num_slots = 0;
3426                 }
3427
3428                 payload->start_slot = req_payload.start_slot;
3429                 /* work out what is required to happen with this payload */
3430                 if (payload->num_slots != req_payload.num_slots) {
3431
3432                         /* need to push an update for this payload */
3433                         if (req_payload.num_slots) {
3434                                 drm_dp_create_payload_step1(mgr, vcpi->vcpi,
3435                                                             &req_payload);
3436                                 payload->num_slots = req_payload.num_slots;
3437                                 payload->vcpi = req_payload.vcpi;
3438
3439                         } else if (payload->num_slots) {
3440                                 payload->num_slots = 0;
3441                                 drm_dp_destroy_payload_step1(mgr, port,
3442                                                              payload->vcpi,
3443                                                              payload);
3444                                 req_payload.payload_state =
3445                                         payload->payload_state;
3446                                 payload->start_slot = 0;
3447                         }
3448                         payload->payload_state = req_payload.payload_state;
3449                 }
3450                 cur_slots += req_payload.num_slots;
3451
3452                 if (put_port)
3453                         drm_dp_mst_topology_put_port(port);
3454         }
3455
3456         for (i = 0; i < mgr->max_payloads; /* do nothing */) {
3457                 if (mgr->payloads[i].payload_state != DP_PAYLOAD_DELETE_LOCAL) {
3458                         i++;
3459                         continue;
3460                 }
3461
3462                 drm_dbg_kms(mgr->dev, "removing payload %d\n", i);
3463                 for (j = i; j < mgr->max_payloads - 1; j++) {
3464                         mgr->payloads[j] = mgr->payloads[j + 1];
3465                         mgr->proposed_vcpis[j] = mgr->proposed_vcpis[j + 1];
3466
3467                         if (mgr->proposed_vcpis[j] &&
3468                             mgr->proposed_vcpis[j]->num_slots) {
3469                                 set_bit(j + 1, &mgr->payload_mask);
3470                         } else {
3471                                 clear_bit(j + 1, &mgr->payload_mask);
3472                         }
3473                 }
3474
3475                 memset(&mgr->payloads[mgr->max_payloads - 1], 0,
3476                        sizeof(struct drm_dp_payload));
3477                 mgr->proposed_vcpis[mgr->max_payloads - 1] = NULL;
3478                 clear_bit(mgr->max_payloads, &mgr->payload_mask);
3479         }
3480         mutex_unlock(&mgr->payload_lock);
3481
3482         return 0;
3483 }
3484 EXPORT_SYMBOL(drm_dp_update_payload_part1);
3485
3486 /**
3487  * drm_dp_update_payload_part2() - Execute payload update part 2
3488  * @mgr: manager to use.
3489  *
3490  * This iterates over all proposed virtual channels, and tries to
3491  * allocate space in the link for them. For 0->slots transitions,
3492  * this step writes the remote VC payload commands. For slots->0
3493  * this just resets some internal state.
3494  */
3495 int drm_dp_update_payload_part2(struct drm_dp_mst_topology_mgr *mgr)
3496 {
3497         struct drm_dp_mst_port *port;
3498         int i;
3499         int ret = 0;
3500         bool skip;
3501
3502         mutex_lock(&mgr->payload_lock);
3503         for (i = 0; i < mgr->max_payloads; i++) {
3504
3505                 if (!mgr->proposed_vcpis[i])
3506                         continue;
3507
3508                 port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
3509
3510                 mutex_lock(&mgr->lock);
3511                 skip = !drm_dp_mst_port_downstream_of_branch(port, mgr->mst_primary);
3512                 mutex_unlock(&mgr->lock);
3513
3514                 if (skip)
3515                         continue;
3516
3517                 drm_dbg_kms(mgr->dev, "payload %d %d\n", i, mgr->payloads[i].payload_state);
3518                 if (mgr->payloads[i].payload_state == DP_PAYLOAD_LOCAL) {
3519                         ret = drm_dp_create_payload_step2(mgr, port, mgr->proposed_vcpis[i]->vcpi, &mgr->payloads[i]);
3520                 } else if (mgr->payloads[i].payload_state == DP_PAYLOAD_DELETE_LOCAL) {
3521                         ret = drm_dp_destroy_payload_step2(mgr, mgr->proposed_vcpis[i]->vcpi, &mgr->payloads[i]);
3522                 }
3523                 if (ret) {
3524                         mutex_unlock(&mgr->payload_lock);
3525                         return ret;
3526                 }
3527         }
3528         mutex_unlock(&mgr->payload_lock);
3529         return 0;
3530 }
3531 EXPORT_SYMBOL(drm_dp_update_payload_part2);
3532
3533 static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
3534                                  struct drm_dp_mst_port *port,
3535                                  int offset, int size, u8 *bytes)
3536 {
3537         int ret = 0;
3538         struct drm_dp_sideband_msg_tx *txmsg;
3539         struct drm_dp_mst_branch *mstb;
3540
3541         mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
3542         if (!mstb)
3543                 return -EINVAL;
3544
3545         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3546         if (!txmsg) {
3547                 ret = -ENOMEM;
3548                 goto fail_put;
3549         }
3550
3551         build_dpcd_read(txmsg, port->port_num, offset, size);
3552         txmsg->dst = port->parent;
3553
3554         drm_dp_queue_down_tx(mgr, txmsg);
3555
3556         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3557         if (ret < 0)
3558                 goto fail_free;
3559
3560         /* DPCD read should never be NACKed */
3561         if (txmsg->reply.reply_type == 1) {
3562                 drm_err(mgr->dev, "mstb %p port %d: DPCD read on addr 0x%x for %d bytes NAKed\n",
3563                         mstb, port->port_num, offset, size);
3564                 ret = -EIO;
3565                 goto fail_free;
3566         }
3567
3568         if (txmsg->reply.u.remote_dpcd_read_ack.num_bytes != size) {
3569                 ret = -EPROTO;
3570                 goto fail_free;
3571         }
3572
3573         ret = min_t(size_t, txmsg->reply.u.remote_dpcd_read_ack.num_bytes,
3574                     size);
3575         memcpy(bytes, txmsg->reply.u.remote_dpcd_read_ack.bytes, ret);
3576
3577 fail_free:
3578         kfree(txmsg);
3579 fail_put:
3580         drm_dp_mst_topology_put_mstb(mstb);
3581
3582         return ret;
3583 }
3584
3585 static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
3586                                   struct drm_dp_mst_port *port,
3587                                   int offset, int size, u8 *bytes)
3588 {
3589         int ret;
3590         struct drm_dp_sideband_msg_tx *txmsg;
3591         struct drm_dp_mst_branch *mstb;
3592
3593         mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
3594         if (!mstb)
3595                 return -EINVAL;
3596
3597         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3598         if (!txmsg) {
3599                 ret = -ENOMEM;
3600                 goto fail_put;
3601         }
3602
3603         build_dpcd_write(txmsg, port->port_num, offset, size, bytes);
3604         txmsg->dst = mstb;
3605
3606         drm_dp_queue_down_tx(mgr, txmsg);
3607
3608         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
3609         if (ret > 0) {
3610                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
3611                         ret = -EIO;
3612                 else
3613                         ret = size;
3614         }
3615
3616         kfree(txmsg);
3617 fail_put:
3618         drm_dp_mst_topology_put_mstb(mstb);
3619         return ret;
3620 }
3621
3622 static int drm_dp_encode_up_ack_reply(struct drm_dp_sideband_msg_tx *msg, u8 req_type)
3623 {
3624         struct drm_dp_sideband_msg_reply_body reply;
3625
3626         reply.reply_type = DP_SIDEBAND_REPLY_ACK;
3627         reply.req_type = req_type;
3628         drm_dp_encode_sideband_reply(&reply, msg);
3629         return 0;
3630 }
3631
3632 static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr,
3633                                     struct drm_dp_mst_branch *mstb,
3634                                     int req_type, bool broadcast)
3635 {
3636         struct drm_dp_sideband_msg_tx *txmsg;
3637
3638         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
3639         if (!txmsg)
3640                 return -ENOMEM;
3641
3642         txmsg->dst = mstb;
3643         drm_dp_encode_up_ack_reply(txmsg, req_type);
3644
3645         mutex_lock(&mgr->qlock);
3646         /* construct a chunk from the first msg in the tx_msg queue */
3647         process_single_tx_qlock(mgr, txmsg, true);
3648         mutex_unlock(&mgr->qlock);
3649
3650         kfree(txmsg);
3651         return 0;
3652 }
3653
3654 /**
3655  * drm_dp_get_vc_payload_bw - get the VC payload BW for an MST link
3656  * @mgr: The &drm_dp_mst_topology_mgr to use
3657  * @link_rate: link rate in 10kbits/s units
3658  * @link_lane_count: lane count
3659  *
3660  * Calculate the total bandwidth of a MultiStream Transport link. The returned
3661  * value is in units of PBNs/(timeslots/1 MTP). This value can be used to
3662  * convert the number of PBNs required for a given stream to the number of
3663  * timeslots this stream requires in each MTP.
3664  */
3665 int drm_dp_get_vc_payload_bw(const struct drm_dp_mst_topology_mgr *mgr,
3666                              int link_rate, int link_lane_count)
3667 {
3668         if (link_rate == 0 || link_lane_count == 0)
3669                 drm_dbg_kms(mgr->dev, "invalid link rate/lane count: (%d / %d)\n",
3670                             link_rate, link_lane_count);
3671
3672         /* See DP v2.0 2.6.4.2, VCPayload_Bandwidth_for_OneTimeSlotPer_MTP_Allocation */
3673         return link_rate * link_lane_count / 54000;
3674 }
3675 EXPORT_SYMBOL(drm_dp_get_vc_payload_bw);
3676
3677 /**
3678  * drm_dp_read_mst_cap() - check whether or not a sink supports MST
3679  * @aux: The DP AUX channel to use
3680  * @dpcd: A cached copy of the DPCD capabilities for this sink
3681  *
3682  * Returns: %True if the sink supports MST, %false otherwise
3683  */
3684 bool drm_dp_read_mst_cap(struct drm_dp_aux *aux,
3685                          const u8 dpcd[DP_RECEIVER_CAP_SIZE])
3686 {
3687         u8 mstm_cap;
3688
3689         if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_12)
3690                 return false;
3691
3692         if (drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &mstm_cap) != 1)
3693                 return false;
3694
3695         return mstm_cap & DP_MST_CAP;
3696 }
3697 EXPORT_SYMBOL(drm_dp_read_mst_cap);
3698
3699 /**
3700  * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager
3701  * @mgr: manager to set state for
3702  * @mst_state: true to enable MST on this connector - false to disable.
3703  *
3704  * This is called by the driver when it detects an MST capable device plugged
3705  * into a DP MST capable port, or when a DP MST capable device is unplugged.
3706  */
3707 int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state)
3708 {
3709         int ret = 0;
3710         struct drm_dp_mst_branch *mstb = NULL;
3711
3712         mutex_lock(&mgr->payload_lock);
3713         mutex_lock(&mgr->lock);
3714         if (mst_state == mgr->mst_state)
3715                 goto out_unlock;
3716
3717         mgr->mst_state = mst_state;
3718         /* set the device into MST mode */
3719         if (mst_state) {
3720                 struct drm_dp_payload reset_pay;
3721                 int lane_count;
3722                 int link_rate;
3723
3724                 WARN_ON(mgr->mst_primary);
3725
3726                 /* get dpcd info */
3727                 ret = drm_dp_read_dpcd_caps(mgr->aux, mgr->dpcd);
3728                 if (ret < 0) {
3729                         drm_dbg_kms(mgr->dev, "%s: failed to read DPCD, ret %d\n",
3730                                     mgr->aux->name, ret);
3731                         goto out_unlock;
3732                 }
3733
3734                 lane_count = min_t(int, mgr->dpcd[2] & DP_MAX_LANE_COUNT_MASK, mgr->max_lane_count);
3735                 link_rate = min_t(int, drm_dp_bw_code_to_link_rate(mgr->dpcd[1]), mgr->max_link_rate);
3736                 mgr->pbn_div = drm_dp_get_vc_payload_bw(mgr,
3737                                                         link_rate,
3738                                                         lane_count);
3739                 if (mgr->pbn_div == 0) {
3740                         ret = -EINVAL;
3741                         goto out_unlock;
3742                 }
3743
3744                 /* add initial branch device at LCT 1 */
3745                 mstb = drm_dp_add_mst_branch_device(1, NULL);
3746                 if (mstb == NULL) {
3747                         ret = -ENOMEM;
3748                         goto out_unlock;
3749                 }
3750                 mstb->mgr = mgr;
3751
3752                 /* give this the main reference */
3753                 mgr->mst_primary = mstb;
3754                 drm_dp_mst_topology_get_mstb(mgr->mst_primary);
3755
3756                 ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
3757                                          DP_MST_EN |
3758                                          DP_UP_REQ_EN |
3759                                          DP_UPSTREAM_IS_SRC);
3760                 if (ret < 0)
3761                         goto out_unlock;
3762
3763                 reset_pay.start_slot = 0;
3764                 reset_pay.num_slots = 0x3f;
3765                 drm_dp_dpcd_write_payload(mgr, 0, &reset_pay);
3766
3767                 queue_work(system_long_wq, &mgr->work);
3768
3769                 ret = 0;
3770         } else {
3771                 /* disable MST on the device */
3772                 mstb = mgr->mst_primary;
3773                 mgr->mst_primary = NULL;
3774                 /* this can fail if the device is gone */
3775                 drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0);
3776                 ret = 0;
3777                 memset(mgr->payloads, 0,
3778                        mgr->max_payloads * sizeof(mgr->payloads[0]));
3779                 memset(mgr->proposed_vcpis, 0,
3780                        mgr->max_payloads * sizeof(mgr->proposed_vcpis[0]));
3781                 mgr->payload_mask = 0;
3782                 set_bit(0, &mgr->payload_mask);
3783                 mgr->vcpi_mask = 0;
3784                 mgr->payload_id_table_cleared = false;
3785         }
3786
3787 out_unlock:
3788         mutex_unlock(&mgr->lock);
3789         mutex_unlock(&mgr->payload_lock);
3790         if (mstb)
3791                 drm_dp_mst_topology_put_mstb(mstb);
3792         return ret;
3793
3794 }
3795 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_set_mst);
3796
3797 static void
3798 drm_dp_mst_topology_mgr_invalidate_mstb(struct drm_dp_mst_branch *mstb)
3799 {
3800         struct drm_dp_mst_port *port;
3801
3802         /* The link address will need to be re-sent on resume */
3803         mstb->link_address_sent = false;
3804
3805         list_for_each_entry(port, &mstb->ports, next)
3806                 if (port->mstb)
3807                         drm_dp_mst_topology_mgr_invalidate_mstb(port->mstb);
3808 }
3809
3810 /**
3811  * drm_dp_mst_topology_mgr_suspend() - suspend the MST manager
3812  * @mgr: manager to suspend
3813  *
3814  * This function tells the MST device that we can't handle UP messages
3815  * anymore. This should stop it from sending any since we are suspended.
3816  */
3817 void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr)
3818 {
3819         mutex_lock(&mgr->lock);
3820         drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
3821                            DP_MST_EN | DP_UPSTREAM_IS_SRC);
3822         mutex_unlock(&mgr->lock);
3823         flush_work(&mgr->up_req_work);
3824         flush_work(&mgr->work);
3825         flush_work(&mgr->delayed_destroy_work);
3826
3827         mutex_lock(&mgr->lock);
3828         if (mgr->mst_state && mgr->mst_primary)
3829                 drm_dp_mst_topology_mgr_invalidate_mstb(mgr->mst_primary);
3830         mutex_unlock(&mgr->lock);
3831 }
3832 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_suspend);
3833
3834 /**
3835  * drm_dp_mst_topology_mgr_resume() - resume the MST manager
3836  * @mgr: manager to resume
3837  * @sync: whether or not to perform topology reprobing synchronously
3838  *
3839  * This will fetch DPCD and see if the device is still there,
3840  * if it is, it will rewrite the MSTM control bits, and return.
3841  *
3842  * If the device fails this returns -1, and the driver should do
3843  * a full MST reprobe, in case we were undocked.
3844  *
3845  * During system resume (where it is assumed that the driver will be calling
3846  * drm_atomic_helper_resume()) this function should be called beforehand with
3847  * @sync set to true. In contexts like runtime resume where the driver is not
3848  * expected to be calling drm_atomic_helper_resume(), this function should be
3849  * called with @sync set to false in order to avoid deadlocking.
3850  *
3851  * Returns: -1 if the MST topology was removed while we were suspended, 0
3852  * otherwise.
3853  */
3854 int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr,
3855                                    bool sync)
3856 {
3857         int ret;
3858         u8 guid[16];
3859
3860         mutex_lock(&mgr->lock);
3861         if (!mgr->mst_primary)
3862                 goto out_fail;
3863
3864         ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd,
3865                                DP_RECEIVER_CAP_SIZE);
3866         if (ret != DP_RECEIVER_CAP_SIZE) {
3867                 drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n");
3868                 goto out_fail;
3869         }
3870
3871         ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
3872                                  DP_MST_EN |
3873                                  DP_UP_REQ_EN |
3874                                  DP_UPSTREAM_IS_SRC);
3875         if (ret < 0) {
3876                 drm_dbg_kms(mgr->dev, "mst write failed - undocked during suspend?\n");
3877                 goto out_fail;
3878         }
3879
3880         /* Some hubs forget their guids after they resume */
3881         ret = drm_dp_dpcd_read(mgr->aux, DP_GUID, guid, 16);
3882         if (ret != 16) {
3883                 drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n");
3884                 goto out_fail;
3885         }
3886
3887         ret = drm_dp_check_mstb_guid(mgr->mst_primary, guid);
3888         if (ret) {
3889                 drm_dbg_kms(mgr->dev, "check mstb failed - undocked during suspend?\n");
3890                 goto out_fail;
3891         }
3892
3893         /*
3894          * For the final step of resuming the topology, we need to bring the
3895          * state of our in-memory topology back into sync with reality. So,
3896          * restart the probing process as if we're probing a new hub
3897          */
3898         queue_work(system_long_wq, &mgr->work);
3899         mutex_unlock(&mgr->lock);
3900
3901         if (sync) {
3902                 drm_dbg_kms(mgr->dev,
3903                             "Waiting for link probe work to finish re-syncing topology...\n");
3904                 flush_work(&mgr->work);
3905         }
3906
3907         return 0;
3908
3909 out_fail:
3910         mutex_unlock(&mgr->lock);
3911         return -1;
3912 }
3913 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume);
3914
3915 static bool
3916 drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up,
3917                       struct drm_dp_mst_branch **mstb)
3918 {
3919         int len;
3920         u8 replyblock[32];
3921         int replylen, curreply;
3922         int ret;
3923         u8 hdrlen;
3924         struct drm_dp_sideband_msg_hdr hdr;
3925         struct drm_dp_sideband_msg_rx *msg =
3926                 up ? &mgr->up_req_recv : &mgr->down_rep_recv;
3927         int basereg = up ? DP_SIDEBAND_MSG_UP_REQ_BASE :
3928                            DP_SIDEBAND_MSG_DOWN_REP_BASE;
3929
3930         if (!up)
3931                 *mstb = NULL;
3932
3933         len = min(mgr->max_dpcd_transaction_bytes, 16);
3934         ret = drm_dp_dpcd_read(mgr->aux, basereg, replyblock, len);
3935         if (ret != len) {
3936                 drm_dbg_kms(mgr->dev, "failed to read DPCD down rep %d %d\n", len, ret);
3937                 return false;
3938         }
3939
3940         ret = drm_dp_decode_sideband_msg_hdr(mgr, &hdr, replyblock, len, &hdrlen);
3941         if (ret == false) {
3942                 print_hex_dump(KERN_DEBUG, "failed hdr", DUMP_PREFIX_NONE, 16,
3943                                1, replyblock, len, false);
3944                 drm_dbg_kms(mgr->dev, "ERROR: failed header\n");
3945                 return false;
3946         }
3947
3948         if (!up) {
3949                 /* Caller is responsible for giving back this reference */
3950                 *mstb = drm_dp_get_mst_branch_device(mgr, hdr.lct, hdr.rad);
3951                 if (!*mstb) {
3952                         drm_dbg_kms(mgr->dev, "Got MST reply from unknown device %d\n", hdr.lct);
3953                         return false;
3954                 }
3955         }
3956
3957         if (!drm_dp_sideband_msg_set_header(msg, &hdr, hdrlen)) {
3958                 drm_dbg_kms(mgr->dev, "sideband msg set header failed %d\n", replyblock[0]);
3959                 return false;
3960         }
3961
3962         replylen = min(msg->curchunk_len, (u8)(len - hdrlen));
3963         ret = drm_dp_sideband_append_payload(msg, replyblock + hdrlen, replylen);
3964         if (!ret) {
3965                 drm_dbg_kms(mgr->dev, "sideband msg build failed %d\n", replyblock[0]);
3966                 return false;
3967         }
3968
3969         replylen = msg->curchunk_len + msg->curchunk_hdrlen - len;
3970         curreply = len;
3971         while (replylen > 0) {
3972                 len = min3(replylen, mgr->max_dpcd_transaction_bytes, 16);
3973                 ret = drm_dp_dpcd_read(mgr->aux, basereg + curreply,
3974                                     replyblock, len);
3975                 if (ret != len) {
3976                         drm_dbg_kms(mgr->dev, "failed to read a chunk (len %d, ret %d)\n",
3977                                     len, ret);
3978                         return false;
3979                 }
3980
3981                 ret = drm_dp_sideband_append_payload(msg, replyblock, len);
3982                 if (!ret) {
3983                         drm_dbg_kms(mgr->dev, "failed to build sideband msg\n");
3984                         return false;
3985                 }
3986
3987                 curreply += len;
3988                 replylen -= len;
3989         }
3990         return true;
3991 }
3992
3993 static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr)
3994 {
3995         struct drm_dp_sideband_msg_tx *txmsg;
3996         struct drm_dp_mst_branch *mstb = NULL;
3997         struct drm_dp_sideband_msg_rx *msg = &mgr->down_rep_recv;
3998
3999         if (!drm_dp_get_one_sb_msg(mgr, false, &mstb))
4000                 goto out;
4001
4002         /* Multi-packet message transmission, don't clear the reply */
4003         if (!msg->have_eomt)
4004                 goto out;
4005
4006         /* find the message */
4007         mutex_lock(&mgr->qlock);
4008         txmsg = list_first_entry_or_null(&mgr->tx_msg_downq,
4009                                          struct drm_dp_sideband_msg_tx, next);
4010         mutex_unlock(&mgr->qlock);
4011
4012         /* Were we actually expecting a response, and from this mstb? */
4013         if (!txmsg || txmsg->dst != mstb) {
4014                 struct drm_dp_sideband_msg_hdr *hdr;
4015
4016                 hdr = &msg->initial_hdr;
4017                 drm_dbg_kms(mgr->dev, "Got MST reply with no msg %p %d %d %02x %02x\n",
4018                             mstb, hdr->seqno, hdr->lct, hdr->rad[0], msg->msg[0]);
4019                 goto out_clear_reply;
4020         }
4021
4022         drm_dp_sideband_parse_reply(mgr, msg, &txmsg->reply);
4023
4024         if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
4025                 drm_dbg_kms(mgr->dev,
4026                             "Got NAK reply: req 0x%02x (%s), reason 0x%02x (%s), nak data 0x%02x\n",
4027                             txmsg->reply.req_type,
4028                             drm_dp_mst_req_type_str(txmsg->reply.req_type),
4029                             txmsg->reply.u.nak.reason,
4030                             drm_dp_mst_nak_reason_str(txmsg->reply.u.nak.reason),
4031                             txmsg->reply.u.nak.nak_data);
4032         }
4033
4034         memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
4035         drm_dp_mst_topology_put_mstb(mstb);
4036
4037         mutex_lock(&mgr->qlock);
4038         txmsg->state = DRM_DP_SIDEBAND_TX_RX;
4039         list_del(&txmsg->next);
4040         mutex_unlock(&mgr->qlock);
4041
4042         wake_up_all(&mgr->tx_waitq);
4043
4044         return 0;
4045
4046 out_clear_reply:
4047         memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
4048 out:
4049         if (mstb)
4050                 drm_dp_mst_topology_put_mstb(mstb);
4051
4052         return 0;
4053 }
4054
4055 static inline bool
4056 drm_dp_mst_process_up_req(struct drm_dp_mst_topology_mgr *mgr,
4057                           struct drm_dp_pending_up_req *up_req)
4058 {
4059         struct drm_dp_mst_branch *mstb = NULL;
4060         struct drm_dp_sideband_msg_req_body *msg = &up_req->msg;
4061         struct drm_dp_sideband_msg_hdr *hdr = &up_req->hdr;
4062         bool hotplug = false;
4063
4064         if (hdr->broadcast) {
4065                 const u8 *guid = NULL;
4066
4067                 if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY)
4068                         guid = msg->u.conn_stat.guid;
4069                 else if (msg->req_type == DP_RESOURCE_STATUS_NOTIFY)
4070                         guid = msg->u.resource_stat.guid;
4071
4072                 if (guid)
4073                         mstb = drm_dp_get_mst_branch_device_by_guid(mgr, guid);
4074         } else {
4075                 mstb = drm_dp_get_mst_branch_device(mgr, hdr->lct, hdr->rad);
4076         }
4077
4078         if (!mstb) {
4079                 drm_dbg_kms(mgr->dev, "Got MST reply from unknown device %d\n", hdr->lct);
4080                 return false;
4081         }
4082
4083         /* TODO: Add missing handler for DP_RESOURCE_STATUS_NOTIFY events */
4084         if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY) {
4085                 drm_dp_mst_handle_conn_stat(mstb, &msg->u.conn_stat);
4086                 hotplug = true;
4087         }
4088
4089         drm_dp_mst_topology_put_mstb(mstb);
4090         return hotplug;
4091 }
4092
4093 static void drm_dp_mst_up_req_work(struct work_struct *work)
4094 {
4095         struct drm_dp_mst_topology_mgr *mgr =
4096                 container_of(work, struct drm_dp_mst_topology_mgr,
4097                              up_req_work);
4098         struct drm_dp_pending_up_req *up_req;
4099         bool send_hotplug = false;
4100
4101         mutex_lock(&mgr->probe_lock);
4102         while (true) {
4103                 mutex_lock(&mgr->up_req_lock);
4104                 up_req = list_first_entry_or_null(&mgr->up_req_list,
4105                                                   struct drm_dp_pending_up_req,
4106                                                   next);
4107                 if (up_req)
4108                         list_del(&up_req->next);
4109                 mutex_unlock(&mgr->up_req_lock);
4110
4111                 if (!up_req)
4112                         break;
4113
4114                 send_hotplug |= drm_dp_mst_process_up_req(mgr, up_req);
4115                 kfree(up_req);
4116         }
4117         mutex_unlock(&mgr->probe_lock);
4118
4119         if (send_hotplug)
4120                 drm_kms_helper_hotplug_event(mgr->dev);
4121 }
4122
4123 static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
4124 {
4125         struct drm_dp_pending_up_req *up_req;
4126
4127         if (!drm_dp_get_one_sb_msg(mgr, true, NULL))
4128                 goto out;
4129
4130         if (!mgr->up_req_recv.have_eomt)
4131                 return 0;
4132
4133         up_req = kzalloc(sizeof(*up_req), GFP_KERNEL);
4134         if (!up_req)
4135                 return -ENOMEM;
4136
4137         INIT_LIST_HEAD(&up_req->next);
4138
4139         drm_dp_sideband_parse_req(mgr, &mgr->up_req_recv, &up_req->msg);
4140
4141         if (up_req->msg.req_type != DP_CONNECTION_STATUS_NOTIFY &&
4142             up_req->msg.req_type != DP_RESOURCE_STATUS_NOTIFY) {
4143                 drm_dbg_kms(mgr->dev, "Received unknown up req type, ignoring: %x\n",
4144                             up_req->msg.req_type);
4145                 kfree(up_req);
4146                 goto out;
4147         }
4148
4149         drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, up_req->msg.req_type,
4150                                  false);
4151
4152         if (up_req->msg.req_type == DP_CONNECTION_STATUS_NOTIFY) {
4153                 const struct drm_dp_connection_status_notify *conn_stat =
4154                         &up_req->msg.u.conn_stat;
4155
4156                 drm_dbg_kms(mgr->dev, "Got CSN: pn: %d ldps:%d ddps: %d mcs: %d ip: %d pdt: %d\n",
4157                             conn_stat->port_number,
4158                             conn_stat->legacy_device_plug_status,
4159                             conn_stat->displayport_device_plug_status,
4160                             conn_stat->message_capability_status,
4161                             conn_stat->input_port,
4162                             conn_stat->peer_device_type);
4163         } else if (up_req->msg.req_type == DP_RESOURCE_STATUS_NOTIFY) {
4164                 const struct drm_dp_resource_status_notify *res_stat =
4165                         &up_req->msg.u.resource_stat;
4166
4167                 drm_dbg_kms(mgr->dev, "Got RSN: pn: %d avail_pbn %d\n",
4168                             res_stat->port_number,
4169                             res_stat->available_pbn);
4170         }
4171
4172         up_req->hdr = mgr->up_req_recv.initial_hdr;
4173         mutex_lock(&mgr->up_req_lock);
4174         list_add_tail(&up_req->next, &mgr->up_req_list);
4175         mutex_unlock(&mgr->up_req_lock);
4176         queue_work(system_long_wq, &mgr->up_req_work);
4177
4178 out:
4179         memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
4180         return 0;
4181 }
4182
4183 /**
4184  * drm_dp_mst_hpd_irq() - MST hotplug IRQ notify
4185  * @mgr: manager to notify irq for.
4186  * @esi: 4 bytes from SINK_COUNT_ESI
4187  * @handled: whether the hpd interrupt was consumed or not
4188  *
4189  * This should be called from the driver when it detects a short IRQ,
4190  * along with the value of the DEVICE_SERVICE_IRQ_VECTOR_ESI0. The
4191  * topology manager will process the sideband messages received as a result
4192  * of this.
4193  */
4194 int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled)
4195 {
4196         int ret = 0;
4197         int sc;
4198         *handled = false;
4199         sc = DP_GET_SINK_COUNT(esi[0]);
4200
4201         if (sc != mgr->sink_count) {
4202                 mgr->sink_count = sc;
4203                 *handled = true;
4204         }
4205
4206         if (esi[1] & DP_DOWN_REP_MSG_RDY) {
4207                 ret = drm_dp_mst_handle_down_rep(mgr);
4208                 *handled = true;
4209         }
4210
4211         if (esi[1] & DP_UP_REQ_MSG_RDY) {
4212                 ret |= drm_dp_mst_handle_up_req(mgr);
4213                 *handled = true;
4214         }
4215
4216         drm_dp_mst_kick_tx(mgr);
4217         return ret;
4218 }
4219 EXPORT_SYMBOL(drm_dp_mst_hpd_irq);
4220
4221 /**
4222  * drm_dp_mst_detect_port() - get connection status for an MST port
4223  * @connector: DRM connector for this port
4224  * @ctx: The acquisition context to use for grabbing locks
4225  * @mgr: manager for this port
4226  * @port: pointer to a port
4227  *
4228  * This returns the current connection state for a port.
4229  */
4230 int
4231 drm_dp_mst_detect_port(struct drm_connector *connector,
4232                        struct drm_modeset_acquire_ctx *ctx,
4233                        struct drm_dp_mst_topology_mgr *mgr,
4234                        struct drm_dp_mst_port *port)
4235 {
4236         int ret;
4237
4238         /* we need to search for the port in the mgr in case it's gone */
4239         port = drm_dp_mst_topology_get_port_validated(mgr, port);
4240         if (!port)
4241                 return connector_status_disconnected;
4242
4243         ret = drm_modeset_lock(&mgr->base.lock, ctx);
4244         if (ret)
4245                 goto out;
4246
4247         ret = connector_status_disconnected;
4248
4249         if (!port->ddps)
4250                 goto out;
4251
4252         switch (port->pdt) {
4253         case DP_PEER_DEVICE_NONE:
4254                 break;
4255         case DP_PEER_DEVICE_MST_BRANCHING:
4256                 if (!port->mcs)
4257                         ret = connector_status_connected;
4258                 break;
4259
4260         case DP_PEER_DEVICE_SST_SINK:
4261                 ret = connector_status_connected;
4262                 /* for logical ports - cache the EDID */
4263                 if (port->port_num >= DP_MST_LOGICAL_PORT_0 && !port->cached_edid)
4264                         port->cached_edid = drm_get_edid(connector, &port->aux.ddc);
4265                 break;
4266         case DP_PEER_DEVICE_DP_LEGACY_CONV:
4267                 if (port->ldps)
4268                         ret = connector_status_connected;
4269                 break;
4270         }
4271 out:
4272         drm_dp_mst_topology_put_port(port);
4273         return ret;
4274 }
4275 EXPORT_SYMBOL(drm_dp_mst_detect_port);
4276
4277 /**
4278  * drm_dp_mst_get_edid() - get EDID for an MST port
4279  * @connector: toplevel connector to get EDID for
4280  * @mgr: manager for this port
4281  * @port: unverified pointer to a port.
4282  *
4283  * This returns an EDID for the port connected to a connector,
4284  * It validates the pointer still exists so the caller doesn't require a
4285  * reference.
4286  */
4287 struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
4288 {
4289         struct edid *edid = NULL;
4290
4291         /* we need to search for the port in the mgr in case it's gone */
4292         port = drm_dp_mst_topology_get_port_validated(mgr, port);
4293         if (!port)
4294                 return NULL;
4295
4296         if (port->cached_edid)
4297                 edid = drm_edid_duplicate(port->cached_edid);
4298         else {
4299                 edid = drm_get_edid(connector, &port->aux.ddc);
4300         }
4301         port->has_audio = drm_detect_monitor_audio(edid);
4302         drm_dp_mst_topology_put_port(port);
4303         return edid;
4304 }
4305 EXPORT_SYMBOL(drm_dp_mst_get_edid);
4306
4307 /**
4308  * drm_dp_find_vcpi_slots() - Find VCPI slots for this PBN value
4309  * @mgr: manager to use
4310  * @pbn: payload bandwidth to convert into slots.
4311  *
4312  * Calculate the number of VCPI slots that will be required for the given PBN
4313  * value. This function is deprecated, and should not be used in atomic
4314  * drivers.
4315  *
4316  * RETURNS:
4317  * The total slots required for this port, or error.
4318  */
4319 int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
4320                            int pbn)
4321 {
4322         int num_slots;
4323
4324         num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
4325
4326         /* max. time slots - one slot for MTP header */
4327         if (num_slots > 63)
4328                 return -ENOSPC;
4329         return num_slots;
4330 }
4331 EXPORT_SYMBOL(drm_dp_find_vcpi_slots);
4332
4333 static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
4334                             struct drm_dp_vcpi *vcpi, int pbn, int slots)
4335 {
4336         int ret;
4337
4338         vcpi->pbn = pbn;
4339         vcpi->aligned_pbn = slots * mgr->pbn_div;
4340         vcpi->num_slots = slots;
4341
4342         ret = drm_dp_mst_assign_payload_id(mgr, vcpi);
4343         if (ret < 0)
4344                 return ret;
4345         return 0;
4346 }
4347
4348 /**
4349  * drm_dp_atomic_find_vcpi_slots() - Find and add VCPI slots to the state
4350  * @state: global atomic state
4351  * @mgr: MST topology manager for the port
4352  * @port: port to find vcpi slots for
4353  * @pbn: bandwidth required for the mode in PBN
4354  * @pbn_div: divider for DSC mode that takes FEC into account
4355  *
4356  * Allocates VCPI slots to @port, replacing any previous VCPI allocations it
4357  * may have had. Any atomic drivers which support MST must call this function
4358  * in their &drm_encoder_helper_funcs.atomic_check() callback to change the
4359  * current VCPI allocation for the new state, but only when
4360  * &drm_crtc_state.mode_changed or &drm_crtc_state.connectors_changed is set
4361  * to ensure compatibility with userspace applications that still use the
4362  * legacy modesetting UAPI.
4363  *
4364  * Allocations set by this function are not checked against the bandwidth
4365  * restraints of @mgr until the driver calls drm_dp_mst_atomic_check().
4366  *
4367  * Additionally, it is OK to call this function multiple times on the same
4368  * @port as needed. It is not OK however, to call this function and
4369  * drm_dp_atomic_release_vcpi_slots() in the same atomic check phase.
4370  *
4371  * See also:
4372  * drm_dp_atomic_release_vcpi_slots()
4373  * drm_dp_mst_atomic_check()
4374  *
4375  * Returns:
4376  * Total slots in the atomic state assigned for this port, or a negative error
4377  * code if the port no longer exists
4378  */
4379 int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
4380                                   struct drm_dp_mst_topology_mgr *mgr,
4381                                   struct drm_dp_mst_port *port, int pbn,
4382                                   int pbn_div)
4383 {
4384         struct drm_dp_mst_topology_state *topology_state;
4385         struct drm_dp_vcpi_allocation *pos, *vcpi = NULL;
4386         int prev_slots, prev_bw, req_slots;
4387
4388         topology_state = drm_atomic_get_mst_topology_state(state, mgr);
4389         if (IS_ERR(topology_state))
4390                 return PTR_ERR(topology_state);
4391
4392         /* Find the current allocation for this port, if any */
4393         list_for_each_entry(pos, &topology_state->vcpis, next) {
4394                 if (pos->port == port) {
4395                         vcpi = pos;
4396                         prev_slots = vcpi->vcpi;
4397                         prev_bw = vcpi->pbn;
4398
4399                         /*
4400                          * This should never happen, unless the driver tries
4401                          * releasing and allocating the same VCPI allocation,
4402                          * which is an error
4403                          */
4404                         if (WARN_ON(!prev_slots)) {
4405                                 drm_err(mgr->dev,
4406                                         "cannot allocate and release VCPI on [MST PORT:%p] in the same state\n",
4407                                         port);
4408                                 return -EINVAL;
4409                         }
4410
4411                         break;
4412                 }
4413         }
4414         if (!vcpi) {
4415                 prev_slots = 0;
4416                 prev_bw = 0;
4417         }
4418
4419         if (pbn_div <= 0)
4420                 pbn_div = mgr->pbn_div;
4421
4422         req_slots = DIV_ROUND_UP(pbn, pbn_div);
4423
4424         drm_dbg_atomic(mgr->dev, "[CONNECTOR:%d:%s] [MST PORT:%p] VCPI %d -> %d\n",
4425                        port->connector->base.id, port->connector->name,
4426                        port, prev_slots, req_slots);
4427         drm_dbg_atomic(mgr->dev, "[CONNECTOR:%d:%s] [MST PORT:%p] PBN %d -> %d\n",
4428                        port->connector->base.id, port->connector->name,
4429                        port, prev_bw, pbn);
4430
4431         /* Add the new allocation to the state */
4432         if (!vcpi) {
4433                 vcpi = kzalloc(sizeof(*vcpi), GFP_KERNEL);
4434                 if (!vcpi)
4435                         return -ENOMEM;
4436
4437                 drm_dp_mst_get_port_malloc(port);
4438                 vcpi->port = port;
4439                 list_add(&vcpi->next, &topology_state->vcpis);
4440         }
4441         vcpi->vcpi = req_slots;
4442         vcpi->pbn = pbn;
4443
4444         return req_slots;
4445 }
4446 EXPORT_SYMBOL(drm_dp_atomic_find_vcpi_slots);
4447
4448 /**
4449  * drm_dp_atomic_release_vcpi_slots() - Release allocated vcpi slots
4450  * @state: global atomic state
4451  * @mgr: MST topology manager for the port
4452  * @port: The port to release the VCPI slots from
4453  *
4454  * Releases any VCPI slots that have been allocated to a port in the atomic
4455  * state. Any atomic drivers which support MST must call this function in
4456  * their &drm_connector_helper_funcs.atomic_check() callback when the
4457  * connector will no longer have VCPI allocated (e.g. because its CRTC was
4458  * removed) when it had VCPI allocated in the previous atomic state.
4459  *
4460  * It is OK to call this even if @port has been removed from the system.
4461  * Additionally, it is OK to call this function multiple times on the same
4462  * @port as needed. It is not OK however, to call this function and
4463  * drm_dp_atomic_find_vcpi_slots() on the same @port in a single atomic check
4464  * phase.
4465  *
4466  * See also:
4467  * drm_dp_atomic_find_vcpi_slots()
4468  * drm_dp_mst_atomic_check()
4469  *
4470  * Returns:
4471  * 0 if all slots for this port were added back to
4472  * &drm_dp_mst_topology_state.avail_slots or negative error code
4473  */
4474 int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
4475                                      struct drm_dp_mst_topology_mgr *mgr,
4476                                      struct drm_dp_mst_port *port)
4477 {
4478         struct drm_dp_mst_topology_state *topology_state;
4479         struct drm_dp_vcpi_allocation *pos;
4480         bool found = false;
4481
4482         topology_state = drm_atomic_get_mst_topology_state(state, mgr);
4483         if (IS_ERR(topology_state))
4484                 return PTR_ERR(topology_state);
4485
4486         list_for_each_entry(pos, &topology_state->vcpis, next) {
4487                 if (pos->port == port) {
4488                         found = true;
4489                         break;
4490                 }
4491         }
4492         if (WARN_ON(!found)) {
4493                 drm_err(mgr->dev, "no VCPI for [MST PORT:%p] found in mst state %p\n",
4494                         port, &topology_state->base);
4495                 return -EINVAL;
4496         }
4497
4498         drm_dbg_atomic(mgr->dev, "[MST PORT:%p] VCPI %d -> 0\n", port, pos->vcpi);
4499         if (pos->vcpi) {
4500                 drm_dp_mst_put_port_malloc(port);
4501                 pos->vcpi = 0;
4502                 pos->pbn = 0;
4503         }
4504
4505         return 0;
4506 }
4507 EXPORT_SYMBOL(drm_dp_atomic_release_vcpi_slots);
4508
4509 /**
4510  * drm_dp_mst_update_slots() - updates the slot info depending on the DP ecoding format
4511  * @mst_state: mst_state to update
4512  * @link_encoding_cap: the ecoding format on the link
4513  */
4514 void drm_dp_mst_update_slots(struct drm_dp_mst_topology_state *mst_state, uint8_t link_encoding_cap)
4515 {
4516         if (link_encoding_cap == DP_CAP_ANSI_128B132B) {
4517                 mst_state->total_avail_slots = 64;
4518                 mst_state->start_slot = 0;
4519         } else {
4520                 mst_state->total_avail_slots = 63;
4521                 mst_state->start_slot = 1;
4522         }
4523
4524         DRM_DEBUG_KMS("%s encoding format on mst_state 0x%p\n",
4525                       (link_encoding_cap == DP_CAP_ANSI_128B132B) ? "128b/132b":"8b/10b",
4526                       mst_state);
4527 }
4528 EXPORT_SYMBOL(drm_dp_mst_update_slots);
4529
4530 /**
4531  * drm_dp_mst_allocate_vcpi() - Allocate a virtual channel
4532  * @mgr: manager for this port
4533  * @port: port to allocate a virtual channel for.
4534  * @pbn: payload bandwidth number to request
4535  * @slots: returned number of slots for this PBN.
4536  */
4537 bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
4538                               struct drm_dp_mst_port *port, int pbn, int slots)
4539 {
4540         int ret;
4541
4542         if (slots < 0)
4543                 return false;
4544
4545         port = drm_dp_mst_topology_get_port_validated(mgr, port);
4546         if (!port)
4547                 return false;
4548
4549         if (port->vcpi.vcpi > 0) {
4550                 drm_dbg_kms(mgr->dev,
4551                             "payload: vcpi %d already allocated for pbn %d - requested pbn %d\n",
4552                             port->vcpi.vcpi, port->vcpi.pbn, pbn);
4553                 if (pbn == port->vcpi.pbn) {
4554                         drm_dp_mst_topology_put_port(port);
4555                         return true;
4556                 }
4557         }
4558
4559         ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn, slots);
4560         if (ret) {
4561                 drm_dbg_kms(mgr->dev, "failed to init vcpi slots=%d ret=%d\n",
4562                             DIV_ROUND_UP(pbn, mgr->pbn_div), ret);
4563                 drm_dp_mst_topology_put_port(port);
4564                 goto out;
4565         }
4566         drm_dbg_kms(mgr->dev, "initing vcpi for pbn=%d slots=%d\n", pbn, port->vcpi.num_slots);
4567
4568         /* Keep port allocated until its payload has been removed */
4569         drm_dp_mst_get_port_malloc(port);
4570         drm_dp_mst_topology_put_port(port);
4571         return true;
4572 out:
4573         return false;
4574 }
4575 EXPORT_SYMBOL(drm_dp_mst_allocate_vcpi);
4576
4577 int drm_dp_mst_get_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
4578 {
4579         int slots = 0;
4580
4581         port = drm_dp_mst_topology_get_port_validated(mgr, port);
4582         if (!port)
4583                 return slots;
4584
4585         slots = port->vcpi.num_slots;
4586         drm_dp_mst_topology_put_port(port);
4587         return slots;
4588 }
4589 EXPORT_SYMBOL(drm_dp_mst_get_vcpi_slots);
4590
4591 /**
4592  * drm_dp_mst_reset_vcpi_slots() - Reset number of slots to 0 for VCPI
4593  * @mgr: manager for this port
4594  * @port: unverified pointer to a port.
4595  *
4596  * This just resets the number of slots for the ports VCPI for later programming.
4597  */
4598 void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
4599 {
4600         /*
4601          * A port with VCPI will remain allocated until its VCPI is
4602          * released, no verified ref needed
4603          */
4604
4605         port->vcpi.num_slots = 0;
4606 }
4607 EXPORT_SYMBOL(drm_dp_mst_reset_vcpi_slots);
4608
4609 /**
4610  * drm_dp_mst_deallocate_vcpi() - deallocate a VCPI
4611  * @mgr: manager for this port
4612  * @port: port to deallocate vcpi for
4613  *
4614  * This can be called unconditionally, regardless of whether
4615  * drm_dp_mst_allocate_vcpi() succeeded or not.
4616  */
4617 void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
4618                                 struct drm_dp_mst_port *port)
4619 {
4620         bool skip;
4621
4622         if (!port->vcpi.vcpi)
4623                 return;
4624
4625         mutex_lock(&mgr->lock);
4626         skip = !drm_dp_mst_port_downstream_of_branch(port, mgr->mst_primary);
4627         mutex_unlock(&mgr->lock);
4628
4629         if (skip)
4630                 return;
4631
4632         drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
4633         port->vcpi.num_slots = 0;
4634         port->vcpi.pbn = 0;
4635         port->vcpi.aligned_pbn = 0;
4636         port->vcpi.vcpi = 0;
4637         drm_dp_mst_put_port_malloc(port);
4638 }
4639 EXPORT_SYMBOL(drm_dp_mst_deallocate_vcpi);
4640
4641 static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
4642                                      int id, struct drm_dp_payload *payload)
4643 {
4644         u8 payload_alloc[3], status;
4645         int ret;
4646         int retries = 0;
4647
4648         drm_dp_dpcd_writeb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS,
4649                            DP_PAYLOAD_TABLE_UPDATED);
4650
4651         payload_alloc[0] = id;
4652         payload_alloc[1] = payload->start_slot;
4653         payload_alloc[2] = payload->num_slots;
4654
4655         ret = drm_dp_dpcd_write(mgr->aux, DP_PAYLOAD_ALLOCATE_SET, payload_alloc, 3);
4656         if (ret != 3) {
4657                 drm_dbg_kms(mgr->dev, "failed to write payload allocation %d\n", ret);
4658                 goto fail;
4659         }
4660
4661 retry:
4662         ret = drm_dp_dpcd_readb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
4663         if (ret < 0) {
4664                 drm_dbg_kms(mgr->dev, "failed to read payload table status %d\n", ret);
4665                 goto fail;
4666         }
4667
4668         if (!(status & DP_PAYLOAD_TABLE_UPDATED)) {
4669                 retries++;
4670                 if (retries < 20) {
4671                         usleep_range(10000, 20000);
4672                         goto retry;
4673                 }
4674                 drm_dbg_kms(mgr->dev, "status not set after read payload table status %d\n",
4675                             status);
4676                 ret = -EINVAL;
4677                 goto fail;
4678         }
4679         ret = 0;
4680 fail:
4681         return ret;
4682 }
4683
4684 static int do_get_act_status(struct drm_dp_aux *aux)
4685 {
4686         int ret;
4687         u8 status;
4688
4689         ret = drm_dp_dpcd_readb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
4690         if (ret < 0)
4691                 return ret;
4692
4693         return status;
4694 }
4695
4696 /**
4697  * drm_dp_check_act_status() - Polls for ACT handled status.
4698  * @mgr: manager to use
4699  *
4700  * Tries waiting for the MST hub to finish updating it's payload table by
4701  * polling for the ACT handled bit for up to 3 seconds (yes-some hubs really
4702  * take that long).
4703  *
4704  * Returns:
4705  * 0 if the ACT was handled in time, negative error code on failure.
4706  */
4707 int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr)
4708 {
4709         /*
4710          * There doesn't seem to be any recommended retry count or timeout in
4711          * the MST specification. Since some hubs have been observed to take
4712          * over 1 second to update their payload allocations under certain
4713          * conditions, we use a rather large timeout value.
4714          */
4715         const int timeout_ms = 3000;
4716         int ret, status;
4717
4718         ret = readx_poll_timeout(do_get_act_status, mgr->aux, status,
4719                                  status & DP_PAYLOAD_ACT_HANDLED || status < 0,
4720                                  200, timeout_ms * USEC_PER_MSEC);
4721         if (ret < 0 && status >= 0) {
4722                 drm_err(mgr->dev, "Failed to get ACT after %dms, last status: %02x\n",
4723                         timeout_ms, status);
4724                 return -EINVAL;
4725         } else if (status < 0) {
4726                 /*
4727                  * Failure here isn't unexpected - the hub may have
4728                  * just been unplugged
4729                  */
4730                 drm_dbg_kms(mgr->dev, "Failed to read payload table status: %d\n", status);
4731                 return status;
4732         }
4733
4734         return 0;
4735 }
4736 EXPORT_SYMBOL(drm_dp_check_act_status);
4737
4738 /**
4739  * drm_dp_calc_pbn_mode() - Calculate the PBN for a mode.
4740  * @clock: dot clock for the mode
4741  * @bpp: bpp for the mode.
4742  * @dsc: DSC mode. If true, bpp has units of 1/16 of a bit per pixel
4743  *
4744  * This uses the formula in the spec to calculate the PBN value for a mode.
4745  */
4746 int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc)
4747 {
4748         /*
4749          * margin 5300ppm + 300ppm ~ 0.6% as per spec, factor is 1.006
4750          * The unit of 54/64Mbytes/sec is an arbitrary unit chosen based on
4751          * common multiplier to render an integer PBN for all link rate/lane
4752          * counts combinations
4753          * calculate
4754          * peak_kbps *= (1006/1000)
4755          * peak_kbps *= (64/54)
4756          * peak_kbps *= 8    convert to bytes
4757          *
4758          * If the bpp is in units of 1/16, further divide by 16. Put this
4759          * factor in the numerator rather than the denominator to avoid
4760          * integer overflow
4761          */
4762
4763         if (dsc)
4764                 return DIV_ROUND_UP_ULL(mul_u32_u32(clock * (bpp / 16), 64 * 1006),
4765                                         8 * 54 * 1000 * 1000);
4766
4767         return DIV_ROUND_UP_ULL(mul_u32_u32(clock * bpp, 64 * 1006),
4768                                 8 * 54 * 1000 * 1000);
4769 }
4770 EXPORT_SYMBOL(drm_dp_calc_pbn_mode);
4771
4772 /* we want to kick the TX after we've ack the up/down IRQs. */
4773 static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr)
4774 {
4775         queue_work(system_long_wq, &mgr->tx_work);
4776 }
4777
4778 /*
4779  * Helper function for parsing DP device types into convenient strings
4780  * for use with dp_mst_topology
4781  */
4782 static const char *pdt_to_string(u8 pdt)
4783 {
4784         switch (pdt) {
4785         case DP_PEER_DEVICE_NONE:
4786                 return "NONE";
4787         case DP_PEER_DEVICE_SOURCE_OR_SST:
4788                 return "SOURCE OR SST";
4789         case DP_PEER_DEVICE_MST_BRANCHING:
4790                 return "MST BRANCHING";
4791         case DP_PEER_DEVICE_SST_SINK:
4792                 return "SST SINK";
4793         case DP_PEER_DEVICE_DP_LEGACY_CONV:
4794                 return "DP LEGACY CONV";
4795         default:
4796                 return "ERR";
4797         }
4798 }
4799
4800 static void drm_dp_mst_dump_mstb(struct seq_file *m,
4801                                  struct drm_dp_mst_branch *mstb)
4802 {
4803         struct drm_dp_mst_port *port;
4804         int tabs = mstb->lct;
4805         char prefix[10];
4806         int i;
4807
4808         for (i = 0; i < tabs; i++)
4809                 prefix[i] = '\t';
4810         prefix[i] = '\0';
4811
4812         seq_printf(m, "%smstb - [%p]: num_ports: %d\n", prefix, mstb, mstb->num_ports);
4813         list_for_each_entry(port, &mstb->ports, next) {
4814                 seq_printf(m, "%sport %d - [%p] (%s - %s): ddps: %d, ldps: %d, sdp: %d/%d, fec: %s, conn: %p\n",
4815                            prefix,
4816                            port->port_num,
4817                            port,
4818                            port->input ? "input" : "output",
4819                            pdt_to_string(port->pdt),
4820                            port->ddps,
4821                            port->ldps,
4822                            port->num_sdp_streams,
4823                            port->num_sdp_stream_sinks,
4824                            port->fec_capable ? "true" : "false",
4825                            port->connector);
4826                 if (port->mstb)
4827                         drm_dp_mst_dump_mstb(m, port->mstb);
4828         }
4829 }
4830
4831 #define DP_PAYLOAD_TABLE_SIZE           64
4832
4833 static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
4834                                   char *buf)
4835 {
4836         int i;
4837
4838         for (i = 0; i < DP_PAYLOAD_TABLE_SIZE; i += 16) {
4839                 if (drm_dp_dpcd_read(mgr->aux,
4840                                      DP_PAYLOAD_TABLE_UPDATE_STATUS + i,
4841                                      &buf[i], 16) != 16)
4842                         return false;
4843         }
4844         return true;
4845 }
4846
4847 static void fetch_monitor_name(struct drm_dp_mst_topology_mgr *mgr,
4848                                struct drm_dp_mst_port *port, char *name,
4849                                int namelen)
4850 {
4851         struct edid *mst_edid;
4852
4853         mst_edid = drm_dp_mst_get_edid(port->connector, mgr, port);
4854         drm_edid_get_monitor_name(mst_edid, name, namelen);
4855 }
4856
4857 /**
4858  * drm_dp_mst_dump_topology(): dump topology to seq file.
4859  * @m: seq_file to dump output to
4860  * @mgr: manager to dump current topology for.
4861  *
4862  * helper to dump MST topology to a seq file for debugfs.
4863  */
4864 void drm_dp_mst_dump_topology(struct seq_file *m,
4865                               struct drm_dp_mst_topology_mgr *mgr)
4866 {
4867         int i;
4868         struct drm_dp_mst_port *port;
4869
4870         mutex_lock(&mgr->lock);
4871         if (mgr->mst_primary)
4872                 drm_dp_mst_dump_mstb(m, mgr->mst_primary);
4873
4874         /* dump VCPIs */
4875         mutex_unlock(&mgr->lock);
4876
4877         mutex_lock(&mgr->payload_lock);
4878         seq_printf(m, "\n*** VCPI Info ***\n");
4879         seq_printf(m, "payload_mask: %lx, vcpi_mask: %lx, max_payloads: %d\n", mgr->payload_mask, mgr->vcpi_mask, mgr->max_payloads);
4880
4881         seq_printf(m, "\n|   idx   |  port # |  vcp_id | # slots |     sink name     |\n");
4882         for (i = 0; i < mgr->max_payloads; i++) {
4883                 if (mgr->proposed_vcpis[i]) {
4884                         char name[14];
4885
4886                         port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
4887                         fetch_monitor_name(mgr, port, name, sizeof(name));
4888                         seq_printf(m, "%10d%10d%10d%10d%20s\n",
4889                                    i,
4890                                    port->port_num,
4891                                    port->vcpi.vcpi,
4892                                    port->vcpi.num_slots,
4893                                    (*name != 0) ? name : "Unknown");
4894                 } else
4895                         seq_printf(m, "%6d - Unused\n", i);
4896         }
4897         seq_printf(m, "\n*** Payload Info ***\n");
4898         seq_printf(m, "|   idx   |  state  |  start slot  | # slots |\n");
4899         for (i = 0; i < mgr->max_payloads; i++) {
4900                 seq_printf(m, "%10d%10d%15d%10d\n",
4901                            i,
4902                            mgr->payloads[i].payload_state,
4903                            mgr->payloads[i].start_slot,
4904                            mgr->payloads[i].num_slots);
4905         }
4906         mutex_unlock(&mgr->payload_lock);
4907
4908         seq_printf(m, "\n*** DPCD Info ***\n");
4909         mutex_lock(&mgr->lock);
4910         if (mgr->mst_primary) {
4911                 u8 buf[DP_PAYLOAD_TABLE_SIZE];
4912                 int ret;
4913
4914                 ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf, DP_RECEIVER_CAP_SIZE);
4915                 if (ret) {
4916                         seq_printf(m, "dpcd read failed\n");
4917                         goto out;
4918                 }
4919                 seq_printf(m, "dpcd: %*ph\n", DP_RECEIVER_CAP_SIZE, buf);
4920
4921                 ret = drm_dp_dpcd_read(mgr->aux, DP_FAUX_CAP, buf, 2);
4922                 if (ret) {
4923                         seq_printf(m, "faux/mst read failed\n");
4924                         goto out;
4925                 }
4926                 seq_printf(m, "faux/mst: %*ph\n", 2, buf);
4927
4928                 ret = drm_dp_dpcd_read(mgr->aux, DP_MSTM_CTRL, buf, 1);
4929                 if (ret) {
4930                         seq_printf(m, "mst ctrl read failed\n");
4931                         goto out;
4932                 }
4933                 seq_printf(m, "mst ctrl: %*ph\n", 1, buf);
4934
4935                 /* dump the standard OUI branch header */
4936                 ret = drm_dp_dpcd_read(mgr->aux, DP_BRANCH_OUI, buf, DP_BRANCH_OUI_HEADER_SIZE);
4937                 if (ret) {
4938                         seq_printf(m, "branch oui read failed\n");
4939                         goto out;
4940                 }
4941                 seq_printf(m, "branch oui: %*phN devid: ", 3, buf);
4942
4943                 for (i = 0x3; i < 0x8 && buf[i]; i++)
4944                         seq_printf(m, "%c", buf[i]);
4945                 seq_printf(m, " revision: hw: %x.%x sw: %x.%x\n",
4946                            buf[0x9] >> 4, buf[0x9] & 0xf, buf[0xa], buf[0xb]);
4947                 if (dump_dp_payload_table(mgr, buf))
4948                         seq_printf(m, "payload table: %*ph\n", DP_PAYLOAD_TABLE_SIZE, buf);
4949         }
4950
4951 out:
4952         mutex_unlock(&mgr->lock);
4953
4954 }
4955 EXPORT_SYMBOL(drm_dp_mst_dump_topology);
4956
4957 static void drm_dp_tx_work(struct work_struct *work)
4958 {
4959         struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, tx_work);
4960
4961         mutex_lock(&mgr->qlock);
4962         if (!list_empty(&mgr->tx_msg_downq))
4963                 process_single_down_tx_qlock(mgr);
4964         mutex_unlock(&mgr->qlock);
4965 }
4966
4967 static inline void
4968 drm_dp_delayed_destroy_port(struct drm_dp_mst_port *port)
4969 {
4970         drm_dp_port_set_pdt(port, DP_PEER_DEVICE_NONE, port->mcs);
4971
4972         if (port->connector) {
4973                 drm_connector_unregister(port->connector);
4974                 drm_connector_put(port->connector);
4975         }
4976
4977         drm_dp_mst_put_port_malloc(port);
4978 }
4979
4980 static inline void
4981 drm_dp_delayed_destroy_mstb(struct drm_dp_mst_branch *mstb)
4982 {
4983         struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
4984         struct drm_dp_mst_port *port, *port_tmp;
4985         struct drm_dp_sideband_msg_tx *txmsg, *txmsg_tmp;
4986         bool wake_tx = false;
4987
4988         mutex_lock(&mgr->lock);
4989         list_for_each_entry_safe(port, port_tmp, &mstb->ports, next) {
4990                 list_del(&port->next);
4991                 drm_dp_mst_topology_put_port(port);
4992         }
4993         mutex_unlock(&mgr->lock);
4994
4995         /* drop any tx slot msg */
4996         mutex_lock(&mstb->mgr->qlock);
4997         list_for_each_entry_safe(txmsg, txmsg_tmp, &mgr->tx_msg_downq, next) {
4998                 if (txmsg->dst != mstb)
4999                         continue;
5000
5001                 txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
5002                 list_del(&txmsg->next);
5003                 wake_tx = true;
5004         }
5005         mutex_unlock(&mstb->mgr->qlock);
5006
5007         if (wake_tx)
5008                 wake_up_all(&mstb->mgr->tx_waitq);
5009
5010         drm_dp_mst_put_mstb_malloc(mstb);
5011 }
5012
5013 static void drm_dp_delayed_destroy_work(struct work_struct *work)
5014 {
5015         struct drm_dp_mst_topology_mgr *mgr =
5016                 container_of(work, struct drm_dp_mst_topology_mgr,
5017                              delayed_destroy_work);
5018         bool send_hotplug = false, go_again;
5019
5020         /*
5021          * Not a regular list traverse as we have to drop the destroy
5022          * connector lock before destroying the mstb/port, to avoid AB->BA
5023          * ordering between this lock and the config mutex.
5024          */
5025         do {
5026                 go_again = false;
5027
5028                 for (;;) {
5029                         struct drm_dp_mst_branch *mstb;
5030
5031                         mutex_lock(&mgr->delayed_destroy_lock);
5032                         mstb = list_first_entry_or_null(&mgr->destroy_branch_device_list,
5033                                                         struct drm_dp_mst_branch,
5034                                                         destroy_next);
5035                         if (mstb)
5036                                 list_del(&mstb->destroy_next);
5037                         mutex_unlock(&mgr->delayed_destroy_lock);
5038
5039                         if (!mstb)
5040                                 break;
5041
5042                         drm_dp_delayed_destroy_mstb(mstb);
5043                         go_again = true;
5044                 }
5045
5046                 for (;;) {
5047                         struct drm_dp_mst_port *port;
5048
5049                         mutex_lock(&mgr->delayed_destroy_lock);
5050                         port = list_first_entry_or_null(&mgr->destroy_port_list,
5051                                                         struct drm_dp_mst_port,
5052                                                         next);
5053                         if (port)
5054                                 list_del(&port->next);
5055                         mutex_unlock(&mgr->delayed_destroy_lock);
5056
5057                         if (!port)
5058                                 break;
5059
5060                         drm_dp_delayed_destroy_port(port);
5061                         send_hotplug = true;
5062                         go_again = true;
5063                 }
5064         } while (go_again);
5065
5066         if (send_hotplug)
5067                 drm_kms_helper_hotplug_event(mgr->dev);
5068 }
5069
5070 static struct drm_private_state *
5071 drm_dp_mst_duplicate_state(struct drm_private_obj *obj)
5072 {
5073         struct drm_dp_mst_topology_state *state, *old_state =
5074                 to_dp_mst_topology_state(obj->state);
5075         struct drm_dp_vcpi_allocation *pos, *vcpi;
5076
5077         state = kmemdup(old_state, sizeof(*state), GFP_KERNEL);
5078         if (!state)
5079                 return NULL;
5080
5081         __drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);
5082
5083         INIT_LIST_HEAD(&state->vcpis);
5084
5085         list_for_each_entry(pos, &old_state->vcpis, next) {
5086                 /* Prune leftover freed VCPI allocations */
5087                 if (!pos->vcpi)
5088                         continue;
5089
5090                 vcpi = kmemdup(pos, sizeof(*vcpi), GFP_KERNEL);
5091                 if (!vcpi)
5092                         goto fail;
5093
5094                 drm_dp_mst_get_port_malloc(vcpi->port);
5095                 list_add(&vcpi->next, &state->vcpis);
5096         }
5097
5098         return &state->base;
5099
5100 fail:
5101         list_for_each_entry_safe(pos, vcpi, &state->vcpis, next) {
5102                 drm_dp_mst_put_port_malloc(pos->port);
5103                 kfree(pos);
5104         }
5105         kfree(state);
5106
5107         return NULL;
5108 }
5109
5110 static void drm_dp_mst_destroy_state(struct drm_private_obj *obj,
5111                                      struct drm_private_state *state)
5112 {
5113         struct drm_dp_mst_topology_state *mst_state =
5114                 to_dp_mst_topology_state(state);
5115         struct drm_dp_vcpi_allocation *pos, *tmp;
5116
5117         list_for_each_entry_safe(pos, tmp, &mst_state->vcpis, next) {
5118                 /* We only keep references to ports with non-zero VCPIs */
5119                 if (pos->vcpi)
5120                         drm_dp_mst_put_port_malloc(pos->port);
5121                 kfree(pos);
5122         }
5123
5124         kfree(mst_state);
5125 }
5126
5127 static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port,
5128                                                  struct drm_dp_mst_branch *branch)
5129 {
5130         while (port->parent) {
5131                 if (port->parent == branch)
5132                         return true;
5133
5134                 if (port->parent->port_parent)
5135                         port = port->parent->port_parent;
5136                 else
5137                         break;
5138         }
5139         return false;
5140 }
5141
5142 static int
5143 drm_dp_mst_atomic_check_port_bw_limit(struct drm_dp_mst_port *port,
5144                                       struct drm_dp_mst_topology_state *state);
5145
5146 static int
5147 drm_dp_mst_atomic_check_mstb_bw_limit(struct drm_dp_mst_branch *mstb,
5148                                       struct drm_dp_mst_topology_state *state)
5149 {
5150         struct drm_dp_vcpi_allocation *vcpi;
5151         struct drm_dp_mst_port *port;
5152         int pbn_used = 0, ret;
5153         bool found = false;
5154
5155         /* Check that we have at least one port in our state that's downstream
5156          * of this branch, otherwise we can skip this branch
5157          */
5158         list_for_each_entry(vcpi, &state->vcpis, next) {
5159                 if (!vcpi->pbn ||
5160                     !drm_dp_mst_port_downstream_of_branch(vcpi->port, mstb))
5161                         continue;
5162
5163                 found = true;
5164                 break;
5165         }
5166         if (!found)
5167                 return 0;
5168
5169         if (mstb->port_parent)
5170                 drm_dbg_atomic(mstb->mgr->dev,
5171                                "[MSTB:%p] [MST PORT:%p] Checking bandwidth limits on [MSTB:%p]\n",
5172                                mstb->port_parent->parent, mstb->port_parent, mstb);
5173         else
5174                 drm_dbg_atomic(mstb->mgr->dev, "[MSTB:%p] Checking bandwidth limits\n", mstb);
5175
5176         list_for_each_entry(port, &mstb->ports, next) {
5177                 ret = drm_dp_mst_atomic_check_port_bw_limit(port, state);
5178                 if (ret < 0)
5179                         return ret;
5180
5181                 pbn_used += ret;
5182         }
5183
5184         return pbn_used;
5185 }
5186
5187 static int
5188 drm_dp_mst_atomic_check_port_bw_limit(struct drm_dp_mst_port *port,
5189                                       struct drm_dp_mst_topology_state *state)
5190 {
5191         struct drm_dp_vcpi_allocation *vcpi;
5192         int pbn_used = 0;
5193
5194         if (port->pdt == DP_PEER_DEVICE_NONE)
5195                 return 0;
5196
5197         if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
5198                 bool found = false;
5199
5200                 list_for_each_entry(vcpi, &state->vcpis, next) {
5201                         if (vcpi->port != port)
5202                                 continue;
5203                         if (!vcpi->pbn)
5204                                 return 0;
5205
5206                         found = true;
5207                         break;
5208                 }
5209                 if (!found)
5210                         return 0;
5211
5212                 /*
5213                  * This could happen if the sink deasserted its HPD line, but
5214                  * the branch device still reports it as attached (PDT != NONE).
5215                  */
5216                 if (!port->full_pbn) {
5217                         drm_dbg_atomic(port->mgr->dev,
5218                                        "[MSTB:%p] [MST PORT:%p] no BW available for the port\n",
5219                                        port->parent, port);
5220                         return -EINVAL;
5221                 }
5222
5223                 pbn_used = vcpi->pbn;
5224         } else {
5225                 pbn_used = drm_dp_mst_atomic_check_mstb_bw_limit(port->mstb,
5226                                                                  state);
5227                 if (pbn_used <= 0)
5228                         return pbn_used;
5229         }
5230
5231         if (pbn_used > port->full_pbn) {
5232                 drm_dbg_atomic(port->mgr->dev,
5233                                "[MSTB:%p] [MST PORT:%p] required PBN of %d exceeds port limit of %d\n",
5234                                port->parent, port, pbn_used, port->full_pbn);
5235                 return -ENOSPC;
5236         }
5237
5238         drm_dbg_atomic(port->mgr->dev, "[MSTB:%p] [MST PORT:%p] uses %d out of %d PBN\n",
5239                        port->parent, port, pbn_used, port->full_pbn);
5240
5241         return pbn_used;
5242 }
5243
5244 static inline int
5245 drm_dp_mst_atomic_check_vcpi_alloc_limit(struct drm_dp_mst_topology_mgr *mgr,
5246                                          struct drm_dp_mst_topology_state *mst_state)
5247 {
5248         struct drm_dp_vcpi_allocation *vcpi;
5249         int avail_slots = mst_state->total_avail_slots, payload_count = 0;
5250
5251         list_for_each_entry(vcpi, &mst_state->vcpis, next) {
5252                 /* Releasing VCPI is always OK-even if the port is gone */
5253                 if (!vcpi->vcpi) {
5254                         drm_dbg_atomic(mgr->dev, "[MST PORT:%p] releases all VCPI slots\n",
5255                                        vcpi->port);
5256                         continue;
5257                 }
5258
5259                 drm_dbg_atomic(mgr->dev, "[MST PORT:%p] requires %d vcpi slots\n",
5260                                vcpi->port, vcpi->vcpi);
5261
5262                 avail_slots -= vcpi->vcpi;
5263                 if (avail_slots < 0) {
5264                         drm_dbg_atomic(mgr->dev,
5265                                        "[MST PORT:%p] not enough VCPI slots in mst state %p (avail=%d)\n",
5266                                        vcpi->port, mst_state, avail_slots + vcpi->vcpi);
5267                         return -ENOSPC;
5268                 }
5269
5270                 if (++payload_count > mgr->max_payloads) {
5271                         drm_dbg_atomic(mgr->dev,
5272                                        "[MST MGR:%p] state %p has too many payloads (max=%d)\n",
5273                                        mgr, mst_state, mgr->max_payloads);
5274                         return -EINVAL;
5275                 }
5276         }
5277         drm_dbg_atomic(mgr->dev, "[MST MGR:%p] mst state %p VCPI avail=%d used=%d\n",
5278                        mgr, mst_state, avail_slots, mst_state->total_avail_slots - avail_slots);
5279
5280         return 0;
5281 }
5282
5283 /**
5284  * drm_dp_mst_add_affected_dsc_crtcs
5285  * @state: Pointer to the new struct drm_dp_mst_topology_state
5286  * @mgr: MST topology manager
5287  *
5288  * Whenever there is a change in mst topology
5289  * DSC configuration would have to be recalculated
5290  * therefore we need to trigger modeset on all affected
5291  * CRTCs in that topology
5292  *
5293  * See also:
5294  * drm_dp_mst_atomic_enable_dsc()
5295  */
5296 int drm_dp_mst_add_affected_dsc_crtcs(struct drm_atomic_state *state, struct drm_dp_mst_topology_mgr *mgr)
5297 {
5298         struct drm_dp_mst_topology_state *mst_state;
5299         struct drm_dp_vcpi_allocation *pos;
5300         struct drm_connector *connector;
5301         struct drm_connector_state *conn_state;
5302         struct drm_crtc *crtc;
5303         struct drm_crtc_state *crtc_state;
5304
5305         mst_state = drm_atomic_get_mst_topology_state(state, mgr);
5306
5307         if (IS_ERR(mst_state))
5308                 return -EINVAL;
5309
5310         list_for_each_entry(pos, &mst_state->vcpis, next) {
5311
5312                 connector = pos->port->connector;
5313
5314                 if (!connector)
5315                         return -EINVAL;
5316
5317                 conn_state = drm_atomic_get_connector_state(state, connector);
5318
5319                 if (IS_ERR(conn_state))
5320                         return PTR_ERR(conn_state);
5321
5322                 crtc = conn_state->crtc;
5323
5324                 if (!crtc)
5325                         continue;
5326
5327                 if (!drm_dp_mst_dsc_aux_for_port(pos->port))
5328                         continue;
5329
5330                 crtc_state = drm_atomic_get_crtc_state(mst_state->base.state, crtc);
5331
5332                 if (IS_ERR(crtc_state))
5333                         return PTR_ERR(crtc_state);
5334
5335                 drm_dbg_atomic(mgr->dev, "[MST MGR:%p] Setting mode_changed flag on CRTC %p\n",
5336                                mgr, crtc);
5337
5338                 crtc_state->mode_changed = true;
5339         }
5340         return 0;
5341 }
5342 EXPORT_SYMBOL(drm_dp_mst_add_affected_dsc_crtcs);
5343
5344 /**
5345  * drm_dp_mst_atomic_enable_dsc - Set DSC Enable Flag to On/Off
5346  * @state: Pointer to the new drm_atomic_state
5347  * @port: Pointer to the affected MST Port
5348  * @pbn: Newly recalculated bw required for link with DSC enabled
5349  * @pbn_div: Divider to calculate correct number of pbn per slot
5350  * @enable: Boolean flag to enable or disable DSC on the port
5351  *
5352  * This function enables DSC on the given Port
5353  * by recalculating its vcpi from pbn provided
5354  * and sets dsc_enable flag to keep track of which
5355  * ports have DSC enabled
5356  *
5357  */
5358 int drm_dp_mst_atomic_enable_dsc(struct drm_atomic_state *state,
5359                                  struct drm_dp_mst_port *port,
5360                                  int pbn, int pbn_div,
5361                                  bool enable)
5362 {
5363         struct drm_dp_mst_topology_state *mst_state;
5364         struct drm_dp_vcpi_allocation *pos;
5365         bool found = false;
5366         int vcpi = 0;
5367
5368         mst_state = drm_atomic_get_mst_topology_state(state, port->mgr);
5369
5370         if (IS_ERR(mst_state))
5371                 return PTR_ERR(mst_state);
5372
5373         list_for_each_entry(pos, &mst_state->vcpis, next) {
5374                 if (pos->port == port) {
5375                         found = true;
5376                         break;
5377                 }
5378         }
5379
5380         if (!found) {
5381                 drm_dbg_atomic(state->dev,
5382                                "[MST PORT:%p] Couldn't find VCPI allocation in mst state %p\n",
5383                                port, mst_state);
5384                 return -EINVAL;
5385         }
5386
5387         if (pos->dsc_enabled == enable) {
5388                 drm_dbg_atomic(state->dev,
5389                                "[MST PORT:%p] DSC flag is already set to %d, returning %d VCPI slots\n",
5390                                port, enable, pos->vcpi);
5391                 vcpi = pos->vcpi;
5392         }
5393
5394         if (enable) {
5395                 vcpi = drm_dp_atomic_find_vcpi_slots(state, port->mgr, port, pbn, pbn_div);
5396                 drm_dbg_atomic(state->dev,
5397                                "[MST PORT:%p] Enabling DSC flag, reallocating %d VCPI slots on the port\n",
5398                                port, vcpi);
5399                 if (vcpi < 0)
5400                         return -EINVAL;
5401         }
5402
5403         pos->dsc_enabled = enable;
5404
5405         return vcpi;
5406 }
5407 EXPORT_SYMBOL(drm_dp_mst_atomic_enable_dsc);
5408 /**
5409  * drm_dp_mst_atomic_check - Check that the new state of an MST topology in an
5410  * atomic update is valid
5411  * @state: Pointer to the new &struct drm_dp_mst_topology_state
5412  *
5413  * Checks the given topology state for an atomic update to ensure that it's
5414  * valid. This includes checking whether there's enough bandwidth to support
5415  * the new VCPI allocations in the atomic update.
5416  *
5417  * Any atomic drivers supporting DP MST must make sure to call this after
5418  * checking the rest of their state in their
5419  * &drm_mode_config_funcs.atomic_check() callback.
5420  *
5421  * See also:
5422  * drm_dp_atomic_find_vcpi_slots()
5423  * drm_dp_atomic_release_vcpi_slots()
5424  *
5425  * Returns:
5426  *
5427  * 0 if the new state is valid, negative error code otherwise.
5428  */
5429 int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
5430 {
5431         struct drm_dp_mst_topology_mgr *mgr;
5432         struct drm_dp_mst_topology_state *mst_state;
5433         int i, ret = 0;
5434
5435         for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) {
5436                 if (!mgr->mst_state)
5437                         continue;
5438
5439                 ret = drm_dp_mst_atomic_check_vcpi_alloc_limit(mgr, mst_state);
5440                 if (ret)
5441                         break;
5442
5443                 mutex_lock(&mgr->lock);
5444                 ret = drm_dp_mst_atomic_check_mstb_bw_limit(mgr->mst_primary,
5445                                                             mst_state);
5446                 mutex_unlock(&mgr->lock);
5447                 if (ret < 0)
5448                         break;
5449                 else
5450                         ret = 0;
5451         }
5452
5453         return ret;
5454 }
5455 EXPORT_SYMBOL(drm_dp_mst_atomic_check);
5456
5457 const struct drm_private_state_funcs drm_dp_mst_topology_state_funcs = {
5458         .atomic_duplicate_state = drm_dp_mst_duplicate_state,
5459         .atomic_destroy_state = drm_dp_mst_destroy_state,
5460 };
5461 EXPORT_SYMBOL(drm_dp_mst_topology_state_funcs);
5462
5463 /**
5464  * drm_atomic_get_mst_topology_state: get MST topology state
5465  *
5466  * @state: global atomic state
5467  * @mgr: MST topology manager, also the private object in this case
5468  *
5469  * This function wraps drm_atomic_get_priv_obj_state() passing in the MST atomic
5470  * state vtable so that the private object state returned is that of a MST
5471  * topology object. Also, drm_atomic_get_private_obj_state() expects the caller
5472  * to care of the locking, so warn if don't hold the connection_mutex.
5473  *
5474  * RETURNS:
5475  *
5476  * The MST topology state or error pointer.
5477  */
5478 struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
5479                                                                     struct drm_dp_mst_topology_mgr *mgr)
5480 {
5481         return to_dp_mst_topology_state(drm_atomic_get_private_obj_state(state, &mgr->base));
5482 }
5483 EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
5484
5485 /**
5486  * drm_dp_mst_topology_mgr_init - initialise a topology manager
5487  * @mgr: manager struct to initialise
5488  * @dev: device providing this structure - for i2c addition.
5489  * @aux: DP helper aux channel to talk to this device
5490  * @max_dpcd_transaction_bytes: hw specific DPCD transaction limit
5491  * @max_payloads: maximum number of payloads this GPU can source
5492  * @max_lane_count: maximum number of lanes this GPU supports
5493  * @max_link_rate: maximum link rate per lane this GPU supports in kHz
5494  * @conn_base_id: the connector object ID the MST device is connected to.
5495  *
5496  * Return 0 for success, or negative error code on failure
5497  */
5498 int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
5499                                  struct drm_device *dev, struct drm_dp_aux *aux,
5500                                  int max_dpcd_transaction_bytes, int max_payloads,
5501                                  int max_lane_count, int max_link_rate,
5502                                  int conn_base_id)
5503 {
5504         struct drm_dp_mst_topology_state *mst_state;
5505
5506         mutex_init(&mgr->lock);
5507         mutex_init(&mgr->qlock);
5508         mutex_init(&mgr->payload_lock);
5509         mutex_init(&mgr->delayed_destroy_lock);
5510         mutex_init(&mgr->up_req_lock);
5511         mutex_init(&mgr->probe_lock);
5512 #if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
5513         mutex_init(&mgr->topology_ref_history_lock);
5514         stack_depot_init();
5515 #endif
5516         INIT_LIST_HEAD(&mgr->tx_msg_downq);
5517         INIT_LIST_HEAD(&mgr->destroy_port_list);
5518         INIT_LIST_HEAD(&mgr->destroy_branch_device_list);
5519         INIT_LIST_HEAD(&mgr->up_req_list);
5520
5521         /*
5522          * delayed_destroy_work will be queued on a dedicated WQ, so that any
5523          * requeuing will be also flushed when deiniting the topology manager.
5524          */
5525         mgr->delayed_destroy_wq = alloc_ordered_workqueue("drm_dp_mst_wq", 0);
5526         if (mgr->delayed_destroy_wq == NULL)
5527                 return -ENOMEM;
5528
5529         INIT_WORK(&mgr->work, drm_dp_mst_link_probe_work);
5530         INIT_WORK(&mgr->tx_work, drm_dp_tx_work);
5531         INIT_WORK(&mgr->delayed_destroy_work, drm_dp_delayed_destroy_work);
5532         INIT_WORK(&mgr->up_req_work, drm_dp_mst_up_req_work);
5533         init_waitqueue_head(&mgr->tx_waitq);
5534         mgr->dev = dev;
5535         mgr->aux = aux;
5536         mgr->max_dpcd_transaction_bytes = max_dpcd_transaction_bytes;
5537         mgr->max_payloads = max_payloads;
5538         mgr->max_lane_count = max_lane_count;
5539         mgr->max_link_rate = max_link_rate;
5540         mgr->conn_base_id = conn_base_id;
5541         if (max_payloads + 1 > sizeof(mgr->payload_mask) * 8 ||
5542             max_payloads + 1 > sizeof(mgr->vcpi_mask) * 8)
5543                 return -EINVAL;
5544         mgr->payloads = kcalloc(max_payloads, sizeof(struct drm_dp_payload), GFP_KERNEL);
5545         if (!mgr->payloads)
5546                 return -ENOMEM;
5547         mgr->proposed_vcpis = kcalloc(max_payloads, sizeof(struct drm_dp_vcpi *), GFP_KERNEL);
5548         if (!mgr->proposed_vcpis)
5549                 return -ENOMEM;
5550         set_bit(0, &mgr->payload_mask);
5551
5552         mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
5553         if (mst_state == NULL)
5554                 return -ENOMEM;
5555
5556         mst_state->total_avail_slots = 63;
5557         mst_state->start_slot = 1;
5558
5559         mst_state->mgr = mgr;
5560         INIT_LIST_HEAD(&mst_state->vcpis);
5561
5562         drm_atomic_private_obj_init(dev, &mgr->base,
5563                                     &mst_state->base,
5564                                     &drm_dp_mst_topology_state_funcs);
5565
5566         return 0;
5567 }
5568 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_init);
5569
5570 /**
5571  * drm_dp_mst_topology_mgr_destroy() - destroy topology manager.
5572  * @mgr: manager to destroy
5573  */
5574 void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr)
5575 {
5576         drm_dp_mst_topology_mgr_set_mst(mgr, false);
5577         flush_work(&mgr->work);
5578         /* The following will also drain any requeued work on the WQ. */
5579         if (mgr->delayed_destroy_wq) {
5580                 destroy_workqueue(mgr->delayed_destroy_wq);
5581                 mgr->delayed_destroy_wq = NULL;
5582         }
5583         mutex_lock(&mgr->payload_lock);
5584         kfree(mgr->payloads);
5585         mgr->payloads = NULL;
5586         kfree(mgr->proposed_vcpis);
5587         mgr->proposed_vcpis = NULL;
5588         mutex_unlock(&mgr->payload_lock);
5589         mgr->dev = NULL;
5590         mgr->aux = NULL;
5591         drm_atomic_private_obj_fini(&mgr->base);
5592         mgr->funcs = NULL;
5593
5594         mutex_destroy(&mgr->delayed_destroy_lock);
5595         mutex_destroy(&mgr->payload_lock);
5596         mutex_destroy(&mgr->qlock);
5597         mutex_destroy(&mgr->lock);
5598         mutex_destroy(&mgr->up_req_lock);
5599         mutex_destroy(&mgr->probe_lock);
5600 #if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
5601         mutex_destroy(&mgr->topology_ref_history_lock);
5602 #endif
5603 }
5604 EXPORT_SYMBOL(drm_dp_mst_topology_mgr_destroy);
5605
5606 static bool remote_i2c_read_ok(const struct i2c_msg msgs[], int num)
5607 {
5608         int i;
5609
5610         if (num - 1 > DP_REMOTE_I2C_READ_MAX_TRANSACTIONS)
5611                 return false;
5612
5613         for (i = 0; i < num - 1; i++) {
5614                 if (msgs[i].flags & I2C_M_RD ||
5615                     msgs[i].len > 0xff)
5616                         return false;
5617         }
5618
5619         return msgs[num - 1].flags & I2C_M_RD &&
5620                 msgs[num - 1].len <= 0xff;
5621 }
5622
5623 static bool remote_i2c_write_ok(const struct i2c_msg msgs[], int num)
5624 {
5625         int i;
5626
5627         for (i = 0; i < num - 1; i++) {
5628                 if (msgs[i].flags & I2C_M_RD || !(msgs[i].flags & I2C_M_STOP) ||
5629                     msgs[i].len > 0xff)
5630                         return false;
5631         }
5632
5633         return !(msgs[num - 1].flags & I2C_M_RD) && msgs[num - 1].len <= 0xff;
5634 }
5635
5636 static int drm_dp_mst_i2c_read(struct drm_dp_mst_branch *mstb,
5637                                struct drm_dp_mst_port *port,
5638                                struct i2c_msg *msgs, int num)
5639 {
5640         struct drm_dp_mst_topology_mgr *mgr = port->mgr;
5641         unsigned int i;
5642         struct drm_dp_sideband_msg_req_body msg;
5643         struct drm_dp_sideband_msg_tx *txmsg = NULL;
5644         int ret;
5645
5646         memset(&msg, 0, sizeof(msg));
5647         msg.req_type = DP_REMOTE_I2C_READ;
5648         msg.u.i2c_read.num_transactions = num - 1;
5649         msg.u.i2c_read.port_number = port->port_num;
5650         for (i = 0; i < num - 1; i++) {
5651                 msg.u.i2c_read.transactions[i].i2c_dev_id = msgs[i].addr;
5652                 msg.u.i2c_read.transactions[i].num_bytes = msgs[i].len;
5653                 msg.u.i2c_read.transactions[i].bytes = msgs[i].buf;
5654                 msg.u.i2c_read.transactions[i].no_stop_bit = !(msgs[i].flags & I2C_M_STOP);
5655         }
5656         msg.u.i2c_read.read_i2c_device_id = msgs[num - 1].addr;
5657         msg.u.i2c_read.num_bytes_read = msgs[num - 1].len;
5658
5659         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
5660         if (!txmsg) {
5661                 ret = -ENOMEM;
5662                 goto out;
5663         }
5664
5665         txmsg->dst = mstb;
5666         drm_dp_encode_sideband_req(&msg, txmsg);
5667
5668         drm_dp_queue_down_tx(mgr, txmsg);
5669
5670         ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
5671         if (ret > 0) {
5672
5673                 if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
5674                         ret = -EREMOTEIO;
5675                         goto out;
5676                 }
5677                 if (txmsg->reply.u.remote_i2c_read_ack.num_bytes != msgs[num - 1].len) {
5678                         ret = -EIO;
5679                         goto out;
5680                 }
5681                 memcpy(msgs[num - 1].buf, txmsg->reply.u.remote_i2c_read_ack.bytes, msgs[num - 1].len);
5682                 ret = num;
5683         }
5684 out:
5685         kfree(txmsg);
5686         return ret;
5687 }
5688
5689 static int drm_dp_mst_i2c_write(struct drm_dp_mst_branch *mstb,
5690                                 struct drm_dp_mst_port *port,
5691                                 struct i2c_msg *msgs, int num)
5692 {
5693         struct drm_dp_mst_topology_mgr *mgr = port->mgr;
5694         unsigned int i;
5695         struct drm_dp_sideband_msg_req_body msg;
5696         struct drm_dp_sideband_msg_tx *txmsg = NULL;
5697         int ret;
5698
5699         txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
5700         if (!txmsg) {
5701                 ret = -ENOMEM;
5702                 goto out;
5703         }
5704         for (i = 0; i < num; i++) {
5705                 memset(&msg, 0, sizeof(msg));
5706                 msg.req_type = DP_REMOTE_I2C_WRITE;
5707                 msg.u.i2c_write.port_number = port->port_num;
5708                 msg.u.i2c_write.write_i2c_device_id = msgs[i].addr;
5709                 msg.u.i2c_write.num_bytes = msgs[i].len;
5710                 msg.u.i2c_write.bytes = msgs[i].buf;
5711
5712                 memset(txmsg, 0, sizeof(*txmsg));
5713                 txmsg->dst = mstb;
5714
5715                 drm_dp_encode_sideband_req(&msg, txmsg);
5716                 drm_dp_queue_down_tx(mgr, txmsg);
5717
5718                 ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
5719                 if (ret > 0) {
5720                         if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
5721                                 ret = -EREMOTEIO;
5722                                 goto out;
5723                         }
5724                 } else {
5725                         goto out;
5726                 }
5727         }
5728         ret = num;
5729 out:
5730         kfree(txmsg);
5731         return ret;
5732 }
5733
5734 /* I2C device */
5735 static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter,
5736                                struct i2c_msg *msgs, int num)
5737 {
5738         struct drm_dp_aux *aux = adapter->algo_data;
5739         struct drm_dp_mst_port *port =
5740                 container_of(aux, struct drm_dp_mst_port, aux);
5741         struct drm_dp_mst_branch *mstb;
5742         struct drm_dp_mst_topology_mgr *mgr = port->mgr;
5743         int ret;
5744
5745         mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
5746         if (!mstb)
5747                 return -EREMOTEIO;
5748
5749         if (remote_i2c_read_ok(msgs, num)) {
5750                 ret = drm_dp_mst_i2c_read(mstb, port, msgs, num);
5751         } else if (remote_i2c_write_ok(msgs, num)) {
5752                 ret = drm_dp_mst_i2c_write(mstb, port, msgs, num);
5753         } else {
5754                 drm_dbg_kms(mgr->dev, "Unsupported I2C transaction for MST device\n");
5755                 ret = -EIO;
5756         }
5757
5758         drm_dp_mst_topology_put_mstb(mstb);
5759         return ret;
5760 }
5761
5762 static u32 drm_dp_mst_i2c_functionality(struct i2c_adapter *adapter)
5763 {
5764         return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
5765                I2C_FUNC_SMBUS_READ_BLOCK_DATA |
5766                I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
5767                I2C_FUNC_10BIT_ADDR;
5768 }
5769
5770 static const struct i2c_algorithm drm_dp_mst_i2c_algo = {
5771         .functionality = drm_dp_mst_i2c_functionality,
5772         .master_xfer = drm_dp_mst_i2c_xfer,
5773 };
5774
5775 /**
5776  * drm_dp_mst_register_i2c_bus() - register an I2C adapter for I2C-over-AUX
5777  * @port: The port to add the I2C bus on
5778  *
5779  * Returns 0 on success or a negative error code on failure.
5780  */
5781 static int drm_dp_mst_register_i2c_bus(struct drm_dp_mst_port *port)
5782 {
5783         struct drm_dp_aux *aux = &port->aux;
5784         struct device *parent_dev = port->mgr->dev->dev;
5785
5786         aux->ddc.algo = &drm_dp_mst_i2c_algo;
5787         aux->ddc.algo_data = aux;
5788         aux->ddc.retries = 3;
5789
5790         aux->ddc.class = I2C_CLASS_DDC;
5791         aux->ddc.owner = THIS_MODULE;
5792         /* FIXME: set the kdev of the port's connector as parent */
5793         aux->ddc.dev.parent = parent_dev;
5794         aux->ddc.dev.of_node = parent_dev->of_node;
5795
5796         strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(parent_dev),
5797                 sizeof(aux->ddc.name));
5798
5799         return i2c_add_adapter(&aux->ddc);
5800 }
5801
5802 /**
5803  * drm_dp_mst_unregister_i2c_bus() - unregister an I2C-over-AUX adapter
5804  * @port: The port to remove the I2C bus from
5805  */
5806 static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_mst_port *port)
5807 {
5808         i2c_del_adapter(&port->aux.ddc);
5809 }
5810
5811 /**
5812  * drm_dp_mst_is_virtual_dpcd() - Is the given port a virtual DP Peer Device
5813  * @port: The port to check
5814  *
5815  * A single physical MST hub object can be represented in the topology
5816  * by multiple branches, with virtual ports between those branches.
5817  *
5818  * As of DP1.4, An MST hub with internal (virtual) ports must expose
5819  * certain DPCD registers over those ports. See sections 2.6.1.1.1
5820  * and 2.6.1.1.2 of Display Port specification v1.4 for details.
5821  *
5822  * May acquire mgr->lock
5823  *
5824  * Returns:
5825  * true if the port is a virtual DP peer device, false otherwise
5826  */
5827 static bool drm_dp_mst_is_virtual_dpcd(struct drm_dp_mst_port *port)
5828 {
5829         struct drm_dp_mst_port *downstream_port;
5830
5831         if (!port || port->dpcd_rev < DP_DPCD_REV_14)
5832                 return false;
5833
5834         /* Virtual DP Sink (Internal Display Panel) */
5835         if (port->port_num >= 8)
5836                 return true;
5837
5838         /* DP-to-HDMI Protocol Converter */
5839         if (port->pdt == DP_PEER_DEVICE_DP_LEGACY_CONV &&
5840             !port->mcs &&
5841             port->ldps)
5842                 return true;
5843
5844         /* DP-to-DP */
5845         mutex_lock(&port->mgr->lock);
5846         if (port->pdt == DP_PEER_DEVICE_MST_BRANCHING &&
5847             port->mstb &&
5848             port->mstb->num_ports == 2) {
5849                 list_for_each_entry(downstream_port, &port->mstb->ports, next) {
5850                         if (downstream_port->pdt == DP_PEER_DEVICE_SST_SINK &&
5851                             !downstream_port->input) {
5852                                 mutex_unlock(&port->mgr->lock);
5853                                 return true;
5854                         }
5855                 }
5856         }
5857         mutex_unlock(&port->mgr->lock);
5858
5859         return false;
5860 }
5861
5862 /**
5863  * drm_dp_mst_dsc_aux_for_port() - Find the correct aux for DSC
5864  * @port: The port to check. A leaf of the MST tree with an attached display.
5865  *
5866  * Depending on the situation, DSC may be enabled via the endpoint aux,
5867  * the immediately upstream aux, or the connector's physical aux.
5868  *
5869  * This is both the correct aux to read DSC_CAPABILITY and the
5870  * correct aux to write DSC_ENABLED.
5871  *
5872  * This operation can be expensive (up to four aux reads), so
5873  * the caller should cache the return.
5874  *
5875  * Returns:
5876  * NULL if DSC cannot be enabled on this port, otherwise the aux device
5877  */
5878 struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port)
5879 {
5880         struct drm_dp_mst_port *immediate_upstream_port;
5881         struct drm_dp_mst_port *fec_port;
5882         struct drm_dp_desc desc = {};
5883         u8 endpoint_fec;
5884         u8 endpoint_dsc;
5885
5886         if (!port)
5887                 return NULL;
5888
5889         if (port->parent->port_parent)
5890                 immediate_upstream_port = port->parent->port_parent;
5891         else
5892                 immediate_upstream_port = NULL;
5893
5894         fec_port = immediate_upstream_port;
5895         while (fec_port) {
5896                 /*
5897                  * Each physical link (i.e. not a virtual port) between the
5898                  * output and the primary device must support FEC
5899                  */
5900                 if (!drm_dp_mst_is_virtual_dpcd(fec_port) &&
5901                     !fec_port->fec_capable)
5902                         return NULL;
5903
5904                 fec_port = fec_port->parent->port_parent;
5905         }
5906
5907         /* DP-to-DP peer device */
5908         if (drm_dp_mst_is_virtual_dpcd(immediate_upstream_port)) {
5909                 u8 upstream_dsc;
5910
5911                 if (drm_dp_dpcd_read(&port->aux,
5912                                      DP_DSC_SUPPORT, &endpoint_dsc, 1) != 1)
5913                         return NULL;
5914                 if (drm_dp_dpcd_read(&port->aux,
5915                                      DP_FEC_CAPABILITY, &endpoint_fec, 1) != 1)
5916                         return NULL;
5917                 if (drm_dp_dpcd_read(&immediate_upstream_port->aux,
5918                                      DP_DSC_SUPPORT, &upstream_dsc, 1) != 1)
5919                         return NULL;
5920
5921                 /* Enpoint decompression with DP-to-DP peer device */
5922                 if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
5923                     (endpoint_fec & DP_FEC_CAPABLE) &&
5924                     (upstream_dsc & 0x2) /* DSC passthrough */)
5925                         return &port->aux;
5926
5927                 /* Virtual DPCD decompression with DP-to-DP peer device */
5928                 return &immediate_upstream_port->aux;
5929         }
5930
5931         /* Virtual DPCD decompression with DP-to-HDMI or Virtual DP Sink */
5932         if (drm_dp_mst_is_virtual_dpcd(port))
5933                 return &port->aux;
5934
5935         /*
5936          * Synaptics quirk
5937          * Applies to ports for which:
5938          * - Physical aux has Synaptics OUI
5939          * - DPv1.4 or higher
5940          * - Port is on primary branch device
5941          * - Not a VGA adapter (DP_DWN_STRM_PORT_TYPE_ANALOG)
5942          */
5943         if (drm_dp_read_desc(port->mgr->aux, &desc, true))
5944                 return NULL;
5945
5946         if (drm_dp_has_quirk(&desc, DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) &&
5947             port->mgr->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14 &&
5948             port->parent == port->mgr->mst_primary) {
5949                 u8 dpcd_ext[DP_RECEIVER_CAP_SIZE];
5950
5951                 if (drm_dp_read_dpcd_caps(port->mgr->aux, dpcd_ext) < 0)
5952                         return NULL;
5953
5954                 if ((dpcd_ext[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT) &&
5955                     ((dpcd_ext[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_TYPE_MASK)
5956                      != DP_DWN_STRM_PORT_TYPE_ANALOG))
5957                         return port->mgr->aux;
5958         }
5959
5960         /*
5961          * The check below verifies if the MST sink
5962          * connected to the GPU is capable of DSC -
5963          * therefore the endpoint needs to be
5964          * both DSC and FEC capable.
5965          */
5966         if (drm_dp_dpcd_read(&port->aux,
5967            DP_DSC_SUPPORT, &endpoint_dsc, 1) != 1)
5968                 return NULL;
5969         if (drm_dp_dpcd_read(&port->aux,
5970            DP_FEC_CAPABILITY, &endpoint_fec, 1) != 1)
5971                 return NULL;
5972         if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
5973            (endpoint_fec & DP_FEC_CAPABLE))
5974                 return &port->aux;
5975
5976         return NULL;
5977 }
5978 EXPORT_SYMBOL(drm_dp_mst_dsc_aux_for_port);