drivers/firewire/core-topology.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Incremental bus scan, based on bus topology
   4  *
   5  * Copyright (C) 2004-2006 Kristian Hoegsberg <krh@bitplanet.net>
   6  */
   7
   8 #include <linux/bug.h>
   9 #include <linux/errno.h>
  10 #include <linux/firewire.h>
  11 #include <linux/firewire-constants.h>
  12 #include <linux/jiffies.h>
  13 #include <linux/kernel.h>
  14 #include <linux/list.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/spinlock.h>
  18
  19 #include <linux/atomic.h>
  20 #include <asm/byteorder.h>
  21
  22 #include "core.h"
  23 #include "phy-packet-definitions.h"
  24 #include <trace/events/firewire.h>
  25
  26 static struct fw_node *fw_node_create(u32 sid, int port_count, int color)
  27 {
  28         struct fw_node *node;
  29
  30         node = kzalloc(struct_size(node, ports, port_count), GFP_ATOMIC);
  31         if (node == NULL)
  32                 return NULL;
  33
  34         node->color = color;
  35         node->node_id = LOCAL_BUS | phy_packet_self_id_get_phy_id(sid);
  36         node->link_on = phy_packet_self_id_zero_get_link_active(sid);
  37         // NOTE: Only two bits, thus only for SCODE_100, SCODE_200, SCODE_400, and SCODE_BETA.
  38         node->phy_speed = phy_packet_self_id_zero_get_scode(sid);
  39         node->initiated_reset = phy_packet_self_id_zero_get_initiated_reset(sid);
  40         node->port_count = port_count;
  41
  42         refcount_set(&node->ref_count, 1);
  43         INIT_LIST_HEAD(&node->link);
  44
  45         return node;
  46 }
  47
  48 /*
  49  * Compute the maximum hop count for this node and it's children.  The
  50  * maximum hop count is the maximum number of connections between any
  51  * two nodes in the subtree rooted at this node.  We need this for
  52  * setting the gap count.  As we build the tree bottom up in
  53  * build_tree() below, this is fairly easy to do: for each node we
  54  * maintain the max hop count and the max depth, ie the number of hops
  55  * to the furthest leaf.  Computing the max hop count breaks down into
  56  * two cases: either the path goes through this node, in which case
  57  * the hop count is the sum of the two biggest child depths plus 2.
  58  * Or it could be the case that the max hop path is entirely
  59  * containted in a child tree, in which case the max hop count is just
  60  * the max hop count of this child.
  61  */
  62 static void update_hop_count(struct fw_node *node)
  63 {
  64         int depths[2] = { -1, -1 };
  65         int max_child_hops = 0;
  66         int i;
  67
  68         for (i = 0; i < node->port_count; i++) {
  69                 if (node->ports[i] == NULL)
  70                         continue;
  71
  72                 if (node->ports[i]->max_hops > max_child_hops)
  73                         max_child_hops = node->ports[i]->max_hops;
  74
  75                 if (node->ports[i]->max_depth > depths[0]) {
  76                         depths[1] = depths[0];
  77                         depths[0] = node->ports[i]->max_depth;
  78                 } else if (node->ports[i]->max_depth > depths[1])
  79                         depths[1] = node->ports[i]->max_depth;
  80         }
  81
  82         node->max_depth = depths[0] + 1;
  83         node->max_hops = max(max_child_hops, depths[0] + depths[1] + 2);
  84 }
  85
  86 static inline struct fw_node *fw_node(struct list_head *l)
  87 {
  88         return list_entry(l, struct fw_node, link);
  89 }
  90
  91 /*
  92  * This function builds the tree representation of the topology given
  93  * by the self IDs from the latest bus reset.  During the construction
  94  * of the tree, the function checks that the self IDs are valid and
  95  * internally consistent.  On success this function returns the
  96  * fw_node corresponding to the local card otherwise NULL.
  97  */
  98 static struct fw_node *build_tree(struct fw_card *card, const u32 *sid, int self_id_count,
  99                                   unsigned int generation)
 100 {
 101         struct self_id_sequence_enumerator enumerator = {
 102                 .cursor = sid,
 103                 .quadlet_count = self_id_count,
 104         };
 105         struct fw_node *node, *child, *local_node, *irm_node;
 106         struct list_head stack;
 107         int phy_id, stack_depth;
 108         int gap_count;
 109         bool beta_repeaters_present;
 110
 111         local_node = NULL;
 112         node = NULL;
 113         INIT_LIST_HEAD(&stack);
 114         stack_depth = 0;
 115         phy_id = 0;
 116         irm_node = NULL;
 117         gap_count = phy_packet_self_id_zero_get_gap_count(*sid);
 118         beta_repeaters_present = false;
 119
 120         while (enumerator.quadlet_count > 0) {
 121                 unsigned int child_port_count = 0;
 122                 unsigned int total_port_count = 0;
 123                 unsigned int parent_count = 0;
 124                 unsigned int quadlet_count;
 125                 const u32 *self_id_sequence;
 126                 unsigned int port_capacity;
 127                 enum phy_packet_self_id_port_status port_status;
 128                 unsigned int port_index;
 129                 struct list_head *h;
 130                 int i;
 131
 132                 self_id_sequence = self_id_sequence_enumerator_next(&enumerator, &quadlet_count);
 133                 if (IS_ERR(self_id_sequence)) {
 134                         if (PTR_ERR(self_id_sequence) != -ENODATA) {
 135                                 fw_err(card, "inconsistent extended self IDs: %ld\n",
 136                                        PTR_ERR(self_id_sequence));
 137                                 return NULL;
 138                         }
 139                         break;
 140                 }
 141
 142                 port_capacity = self_id_sequence_get_port_capacity(quadlet_count);
 143                 trace_self_id_sequence(card->index, self_id_sequence, quadlet_count, generation);
 144
 145                 for (port_index = 0; port_index < port_capacity; ++port_index) {
 146                         port_status = self_id_sequence_get_port_status(self_id_sequence, quadlet_count,
 147                                                                        port_index);
 148                         switch (port_status) {
 149                         case PHY_PACKET_SELF_ID_PORT_STATUS_CHILD:
 150                                 ++child_port_count;
 151                                 fallthrough;
 152                         case PHY_PACKET_SELF_ID_PORT_STATUS_PARENT:
 153                         case PHY_PACKET_SELF_ID_PORT_STATUS_NCONN:
 154                                 ++total_port_count;
 155                                 fallthrough;
 156                         case PHY_PACKET_SELF_ID_PORT_STATUS_NONE:
 157                         default:
 158                                 break;
 159                         }
 160                 }
 161
 162                 if (phy_id != phy_packet_self_id_get_phy_id(self_id_sequence[0])) {
 163                         fw_err(card, "PHY ID mismatch in self ID: %d != %d\n",
 164                                phy_id, phy_packet_self_id_get_phy_id(self_id_sequence[0]));
 165                         return NULL;
 166                 }
 167
 168                 if (child_port_count > stack_depth) {
 169                         fw_err(card, "topology stack underflow\n");
 170                         return NULL;
 171                 }
 172
 173                 /*
 174                  * Seek back from the top of our stack to find the
 175                  * start of the child nodes for this node.
 176                  */
 177                 for (i = 0, h = &stack; i < child_port_count; i++)
 178                         h = h->prev;
 179                 /*
 180                  * When the stack is empty, this yields an invalid value,
 181                  * but that pointer will never be dereferenced.
 182                  */
 183                 child = fw_node(h);
 184
 185                 node = fw_node_create(self_id_sequence[0], total_port_count, card->color);
 186                 if (node == NULL) {
 187                         fw_err(card, "out of memory while building topology\n");
 188                         return NULL;
 189                 }
 190
 191                 if (phy_id == (card->node_id & 0x3f))
 192                         local_node = node;
 193
 194                 if (phy_packet_self_id_zero_get_contender(self_id_sequence[0]))
 195                         irm_node = node;
 196
 197                 for (port_index = 0; port_index < total_port_count; ++port_index) {
 198                         port_status = self_id_sequence_get_port_status(self_id_sequence, quadlet_count,
 199                                                                        port_index);
 200                         switch (port_status) {
 201                         case PHY_PACKET_SELF_ID_PORT_STATUS_PARENT:
 202                                 // Who's your daddy?  We dont know the parent node at this time, so
 203                                 // we temporarily abuse node->color for remembering the entry in
 204                                 // the node->ports array where the parent node should be.  Later,
 205                                 // when we handle the parent node, we fix up the reference.
 206                                 ++parent_count;
 207                                 node->color = i;
 208                                 break;
 209
 210                         case PHY_PACKET_SELF_ID_PORT_STATUS_CHILD:
 211                                 node->ports[port_index] = child;
 212                                 // Fix up parent reference for this child node.
 213                                 child->ports[child->color] = node;
 214                                 child->color = card->color;
 215                                 child = fw_node(child->link.next);
 216                                 break;
 217                         case PHY_PACKET_SELF_ID_PORT_STATUS_NCONN:
 218                         case PHY_PACKET_SELF_ID_PORT_STATUS_NONE:
 219                         default:
 220                                 break;
 221                         }
 222                 }
 223
 224                 // Check that the node reports exactly one parent port, except for the root, which
 225                 // of course should have no parents.
 226                 if ((enumerator.quadlet_count == 0 && parent_count != 0) ||
 227                     (enumerator.quadlet_count > 0 && parent_count != 1)) {
 228                         fw_err(card, "parent port inconsistency for node %d: "
 229                                "parent_count=%d\n", phy_id, parent_count);
 230                         return NULL;
 231                 }
 232
 233                 /* Pop the child nodes off the stack and push the new node. */
 234                 __list_del(h->prev, &stack);
 235                 list_add_tail(&node->link, &stack);
 236                 stack_depth += 1 - child_port_count;
 237
 238                 if (node->phy_speed == SCODE_BETA && parent_count + child_port_count > 1)
 239                         beta_repeaters_present = true;
 240
 241                 // If PHYs report different gap counts, set an invalid count which will force a gap
 242                 // count reconfiguration and a reset.
 243                 if (phy_packet_self_id_zero_get_gap_count(self_id_sequence[0]) != gap_count)
 244                         gap_count = 0;
 245
 246                 update_hop_count(node);
 247
 248                 phy_id++;
 249         }
 250
 251         card->root_node = node;
 252         card->irm_node = irm_node;
 253         card->gap_count = gap_count;
 254         card->beta_repeaters_present = beta_repeaters_present;
 255
 256         return local_node;
 257 }
 258
 259 typedef void (*fw_node_callback_t)(struct fw_card * card,
 260                                    struct fw_node * node,
 261                                    struct fw_node * parent);
 262
 263 static void for_each_fw_node(struct fw_card *card, struct fw_node *root,
 264                              fw_node_callback_t callback)
 265 {
 266         struct list_head list;
 267         struct fw_node *node, *next, *child, *parent;
 268         int i;
 269
 270         INIT_LIST_HEAD(&list);
 271
 272         fw_node_get(root);
 273         list_add_tail(&root->link, &list);
 274         parent = NULL;
 275         list_for_each_entry(node, &list, link) {
 276                 node->color = card->color;
 277
 278                 for (i = 0; i < node->port_count; i++) {
 279                         child = node->ports[i];
 280                         if (!child)
 281                                 continue;
 282                         if (child->color == card->color)
 283                                 parent = child;
 284                         else {
 285                                 fw_node_get(child);
 286                                 list_add_tail(&child->link, &list);
 287                         }
 288                 }
 289
 290                 callback(card, node, parent);
 291         }
 292
 293         list_for_each_entry_safe(node, next, &list, link)
 294                 fw_node_put(node);
 295 }
 296
 297 static void report_lost_node(struct fw_card *card,
 298                              struct fw_node *node, struct fw_node *parent)
 299 {
 300         fw_node_event(card, node, FW_NODE_DESTROYED);
 301         fw_node_put(node);
 302
 303         /* Topology has changed - reset bus manager retry counter */
 304         card->bm_retries = 0;
 305 }
 306
 307 static void report_found_node(struct fw_card *card,
 308                               struct fw_node *node, struct fw_node *parent)
 309 {
 310         int b_path = (node->phy_speed == SCODE_BETA);
 311
 312         if (parent != NULL) {
 313                 /* min() macro doesn't work here with gcc 3.4 */
 314                 node->max_speed = parent->max_speed < node->phy_speed ?
 315                                         parent->max_speed : node->phy_speed;
 316                 node->b_path = parent->b_path && b_path;
 317         } else {
 318                 node->max_speed = node->phy_speed;
 319                 node->b_path = b_path;
 320         }
 321
 322         fw_node_event(card, node, FW_NODE_CREATED);
 323
 324         /* Topology has changed - reset bus manager retry counter */
 325         card->bm_retries = 0;
 326 }
 327
 328 /* Must be called with card->lock held */
 329 void fw_destroy_nodes(struct fw_card *card)
 330 {
 331         card->color++;
 332         if (card->local_node != NULL)
 333                 for_each_fw_node(card, card->local_node, report_lost_node);
 334         card->local_node = NULL;
 335 }
 336
 337 static void move_tree(struct fw_node *node0, struct fw_node *node1, int port)
 338 {
 339         struct fw_node *tree;
 340         int i;
 341
 342         tree = node1->ports[port];
 343         node0->ports[port] = tree;
 344         for (i = 0; i < tree->port_count; i++) {
 345                 if (tree->ports[i] == node1) {
 346                         tree->ports[i] = node0;
 347                         break;
 348                 }
 349         }
 350 }
 351
 352 /*
 353  * Compare the old topology tree for card with the new one specified by root.
 354  * Queue the nodes and mark them as either found, lost or updated.
 355  * Update the nodes in the card topology tree as we go.
 356  */
 357 static void update_tree(struct fw_card *card, struct fw_node *root)
 358 {
 359         struct list_head list0, list1;
 360         struct fw_node *node0, *node1, *next1;
 361         int i, event;
 362
 363         INIT_LIST_HEAD(&list0);
 364         list_add_tail(&card->local_node->link, &list0);
 365         INIT_LIST_HEAD(&list1);
 366         list_add_tail(&root->link, &list1);
 367
 368         node0 = fw_node(list0.next);
 369         node1 = fw_node(list1.next);
 370
 371         while (&node0->link != &list0) {
 372                 WARN_ON(node0->port_count != node1->port_count);
 373
 374                 if (node0->link_on && !node1->link_on)
 375                         event = FW_NODE_LINK_OFF;
 376                 else if (!node0->link_on && node1->link_on)
 377                         event = FW_NODE_LINK_ON;
 378                 else if (node1->initiated_reset && node1->link_on)
 379                         event = FW_NODE_INITIATED_RESET;
 380                 else
 381                         event = FW_NODE_UPDATED;
 382
 383                 node0->node_id = node1->node_id;
 384                 node0->color = card->color;
 385                 node0->link_on = node1->link_on;
 386                 node0->initiated_reset = node1->initiated_reset;
 387                 node0->max_hops = node1->max_hops;
 388                 node1->color = card->color;
 389                 fw_node_event(card, node0, event);
 390
 391                 if (card->root_node == node1)
 392                         card->root_node = node0;
 393                 if (card->irm_node == node1)
 394                         card->irm_node = node0;
 395
 396                 for (i = 0; i < node0->port_count; i++) {
 397                         if (node0->ports[i] && node1->ports[i]) {
 398                                 /*
 399                                  * This port didn't change, queue the
 400                                  * connected node for further
 401                                  * investigation.
 402                                  */
 403                                 if (node0->ports[i]->color == card->color)
 404                                         continue;
 405                                 list_add_tail(&node0->ports[i]->link, &list0);
 406                                 list_add_tail(&node1->ports[i]->link, &list1);
 407                         } else if (node0->ports[i]) {
 408                                 /*
 409                                  * The nodes connected here were
 410                                  * unplugged; unref the lost nodes and
 411                                  * queue FW_NODE_LOST callbacks for
 412                                  * them.
 413                                  */
 414
 415                                 for_each_fw_node(card, node0->ports[i],
 416                                                  report_lost_node);
 417                                 node0->ports[i] = NULL;
 418                         } else if (node1->ports[i]) {
 419                                 /*
 420                                  * One or more node were connected to
 421                                  * this port. Move the new nodes into
 422                                  * the tree and queue FW_NODE_CREATED
 423                                  * callbacks for them.
 424                                  */
 425                                 move_tree(node0, node1, i);
 426                                 for_each_fw_node(card, node0->ports[i],
 427                                                  report_found_node);
 428                         }
 429                 }
 430
 431                 node0 = fw_node(node0->link.next);
 432                 next1 = fw_node(node1->link.next);
 433                 fw_node_put(node1);
 434                 node1 = next1;
 435         }
 436 }
 437
 438 static void update_topology_map(struct fw_card *card,
 439                                 u32 *self_ids, int self_id_count)
 440 {
 441         int node_count = (card->root_node->node_id & 0x3f) + 1;
 442         __be32 *map = card->topology_map;
 443
 444         *map++ = cpu_to_be32((self_id_count + 2) << 16);
 445         *map++ = cpu_to_be32(be32_to_cpu(card->topology_map[1]) + 1);
 446         *map++ = cpu_to_be32((node_count << 16) | self_id_count);
 447
 448         while (self_id_count--)
 449                 *map++ = cpu_to_be32p(self_ids++);
 450
 451         fw_compute_block_crc(card->topology_map);
 452 }
 453
 454 void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,
 455                               int self_id_count, u32 *self_ids, bool bm_abdicate)
 456 {
 457         struct fw_node *local_node;
 458         unsigned long flags;
 459
 460         trace_bus_reset_handle(card->index, generation, node_id, bm_abdicate, self_ids, self_id_count);
 461
 462         spin_lock_irqsave(&card->lock, flags);
 463
 464         /*
 465          * If the selfID buffer is not the immediate successor of the
 466          * previously processed one, we cannot reliably compare the
 467          * old and new topologies.
 468          */
 469         if (!is_next_generation(generation, card->generation) &&
 470             card->local_node != NULL) {
 471                 fw_destroy_nodes(card);
 472                 card->bm_retries = 0;
 473         }
 474
 475         card->broadcast_channel_allocated = card->broadcast_channel_auto_allocated;
 476         card->node_id = node_id;
 477         /*
 478          * Update node_id before generation to prevent anybody from using
 479          * a stale node_id together with a current generation.
 480          */
 481         smp_wmb();
 482         card->generation = generation;
 483         card->reset_jiffies = get_jiffies_64();
 484         card->bm_node_id  = 0xffff;
 485         card->bm_abdicate = bm_abdicate;
 486         fw_schedule_bm_work(card, 0);
 487
 488         local_node = build_tree(card, self_ids, self_id_count, generation);
 489
 490         update_topology_map(card, self_ids, self_id_count);
 491
 492         card->color++;
 493
 494         if (local_node == NULL) {
 495                 fw_err(card, "topology build failed\n");
 496                 /* FIXME: We need to issue a bus reset in this case. */
 497         } else if (card->local_node == NULL) {
 498                 card->local_node = local_node;
 499                 for_each_fw_node(card, local_node, report_found_node);
 500         } else {
 501                 update_tree(card, local_node);
 502         }
 503
 504         spin_unlock_irqrestore(&card->lock, flags);
 505 }
 506 EXPORT_SYMBOL(fw_core_handle_bus_reset);