drivers/nfc/nfcsim.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * NFC hardware simulation driver
   4  * Copyright (c) 2013, Intel Corporation.
   5  */
   6
   7 #include <linux/device.h>
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/ctype.h>
  11 #include <linux/debugfs.h>
  12 #include <linux/nfc.h>
  13 #include <net/nfc/nfc.h>
  14 #include <net/nfc/digital.h>
  15
  16 #define NFCSIM_ERR(d, fmt, args...) nfc_err(&d->nfc_digital_dev->nfc_dev->dev, \
  17                                             "%s: " fmt, __func__, ## args)
  18
  19 #define NFCSIM_DBG(d, fmt, args...) dev_dbg(&d->nfc_digital_dev->nfc_dev->dev, \
  20                                             "%s: " fmt, __func__, ## args)
  21
  22 #define NFCSIM_VERSION "0.2"
  23
  24 #define NFCSIM_MODE_NONE        0
  25 #define NFCSIM_MODE_INITIATOR   1
  26 #define NFCSIM_MODE_TARGET      2
  27
  28 #define NFCSIM_CAPABILITIES (NFC_DIGITAL_DRV_CAPS_IN_CRC   | \
  29                              NFC_DIGITAL_DRV_CAPS_TG_CRC)
  30
  31 struct nfcsim {
  32         struct nfc_digital_dev *nfc_digital_dev;
  33
  34         struct work_struct recv_work;
  35         struct delayed_work send_work;
  36
  37         struct nfcsim_link *link_in;
  38         struct nfcsim_link *link_out;
  39
  40         bool up;
  41         u8 mode;
  42         u8 rf_tech;
  43
  44         u16 recv_timeout;
  45
  46         nfc_digital_cmd_complete_t cb;
  47         void *arg;
  48
  49         u8 dropframe;
  50 };
  51
  52 struct nfcsim_link {
  53         struct mutex lock;
  54
  55         u8 rf_tech;
  56         u8 mode;
  57
  58         u8 shutdown;
  59
  60         struct sk_buff *skb;
  61         wait_queue_head_t recv_wait;
  62         u8 cond;
  63 };
  64
  65 static struct nfcsim_link *nfcsim_link_new(void)
  66 {
  67         struct nfcsim_link *link;
  68
  69         link = kzalloc(sizeof(struct nfcsim_link), GFP_KERNEL);
  70         if (!link)
  71                 return NULL;
  72
  73         mutex_init(&link->lock);
  74         init_waitqueue_head(&link->recv_wait);
  75
  76         return link;
  77 }
  78
  79 static void nfcsim_link_free(struct nfcsim_link *link)
  80 {
  81         dev_kfree_skb(link->skb);
  82         kfree(link);
  83 }
  84
  85 static void nfcsim_link_recv_wake(struct nfcsim_link *link)
  86 {
  87         link->cond = 1;
  88         wake_up_interruptible(&link->recv_wait);
  89 }
  90
  91 static void nfcsim_link_set_skb(struct nfcsim_link *link, struct sk_buff *skb,
  92                                 u8 rf_tech, u8 mode)
  93 {
  94         mutex_lock(&link->lock);
  95
  96         dev_kfree_skb(link->skb);
  97         link->skb = skb;
  98         link->rf_tech = rf_tech;
  99         link->mode = mode;
 100
 101         mutex_unlock(&link->lock);
 102 }
 103
 104 static void nfcsim_link_recv_cancel(struct nfcsim_link *link)
 105 {
 106         mutex_lock(&link->lock);
 107
 108         link->mode = NFCSIM_MODE_NONE;
 109
 110         mutex_unlock(&link->lock);
 111
 112         nfcsim_link_recv_wake(link);
 113 }
 114
 115 static void nfcsim_link_shutdown(struct nfcsim_link *link)
 116 {
 117         mutex_lock(&link->lock);
 118
 119         link->shutdown = 1;
 120         link->mode = NFCSIM_MODE_NONE;
 121
 122         mutex_unlock(&link->lock);
 123
 124         nfcsim_link_recv_wake(link);
 125 }
 126
 127 static struct sk_buff *nfcsim_link_recv_skb(struct nfcsim_link *link,
 128                                             int timeout, u8 rf_tech, u8 mode)
 129 {
 130         int rc;
 131         struct sk_buff *skb;
 132
 133         rc = wait_event_interruptible_timeout(link->recv_wait,
 134                                               link->cond,
 135                                               msecs_to_jiffies(timeout));
 136
 137         mutex_lock(&link->lock);
 138
 139         skb = link->skb;
 140         link->skb = NULL;
 141
 142         if (!rc) {
 143                 rc = -ETIMEDOUT;
 144                 goto done;
 145         }
 146
 147         if (!skb || link->rf_tech != rf_tech || link->mode == mode) {
 148                 rc = -EINVAL;
 149                 goto done;
 150         }
 151
 152         if (link->shutdown) {
 153                 rc = -ENODEV;
 154                 goto done;
 155         }
 156
 157 done:
 158         mutex_unlock(&link->lock);
 159
 160         if (rc < 0) {
 161                 dev_kfree_skb(skb);
 162                 skb = ERR_PTR(rc);
 163         }
 164
 165         link->cond = 0;
 166
 167         return skb;
 168 }
 169
 170 static void nfcsim_send_wq(struct work_struct *work)
 171 {
 172         struct nfcsim *dev = container_of(work, struct nfcsim, send_work.work);
 173
 174         /*
 175          * To effectively send data, the device just wake up its link_out which
 176          * is the link_in of the peer device. The exchanged skb has already been
 177          * stored in the dev->link_out through nfcsim_link_set_skb().
 178          */
 179         nfcsim_link_recv_wake(dev->link_out);
 180 }
 181
 182 static void nfcsim_recv_wq(struct work_struct *work)
 183 {
 184         struct nfcsim *dev = container_of(work, struct nfcsim, recv_work);
 185         struct sk_buff *skb;
 186
 187         skb = nfcsim_link_recv_skb(dev->link_in, dev->recv_timeout,
 188                                    dev->rf_tech, dev->mode);
 189
 190         if (!dev->up) {
 191                 NFCSIM_ERR(dev, "Device is down\n");
 192
 193                 if (!IS_ERR(skb))
 194                         dev_kfree_skb(skb);
 195                 return;
 196         }
 197
 198         dev->cb(dev->nfc_digital_dev, dev->arg, skb);
 199 }
 200
 201 static int nfcsim_send(struct nfc_digital_dev *ddev, struct sk_buff *skb,
 202                        u16 timeout, nfc_digital_cmd_complete_t cb, void *arg)
 203 {
 204         struct nfcsim *dev = nfc_digital_get_drvdata(ddev);
 205         u8 delay;
 206
 207         if (!dev->up) {
 208                 NFCSIM_ERR(dev, "Device is down\n");
 209                 return -ENODEV;
 210         }
 211
 212         dev->recv_timeout = timeout;
 213         dev->cb = cb;
 214         dev->arg = arg;
 215
 216         schedule_work(&dev->recv_work);
 217
 218         if (dev->dropframe) {
 219                 NFCSIM_DBG(dev, "dropping frame (out of %d)\n", dev->dropframe);
 220                 dev_kfree_skb(skb);
 221                 dev->dropframe--;
 222
 223                 return 0;
 224         }
 225
 226         if (skb) {
 227                 nfcsim_link_set_skb(dev->link_out, skb, dev->rf_tech,
 228                                     dev->mode);
 229
 230                 /* Add random delay (between 3 and 10 ms) before sending data */
 231                 get_random_bytes(&delay, 1);
 232                 delay = 3 + (delay & 0x07);
 233
 234                 schedule_delayed_work(&dev->send_work, msecs_to_jiffies(delay));
 235         }
 236
 237         return 0;
 238 }
 239
 240 static void nfcsim_abort_cmd(struct nfc_digital_dev *ddev)
 241 {
 242         const struct nfcsim *dev = nfc_digital_get_drvdata(ddev);
 243
 244         nfcsim_link_recv_cancel(dev->link_in);
 245 }
 246
 247 static int nfcsim_switch_rf(struct nfc_digital_dev *ddev, bool on)
 248 {
 249         struct nfcsim *dev = nfc_digital_get_drvdata(ddev);
 250
 251         dev->up = on;
 252
 253         return 0;
 254 }
 255
 256 static int nfcsim_in_configure_hw(struct nfc_digital_dev *ddev,
 257                                           int type, int param)
 258 {
 259         struct nfcsim *dev = nfc_digital_get_drvdata(ddev);
 260
 261         switch (type) {
 262         case NFC_DIGITAL_CONFIG_RF_TECH:
 263                 dev->up = true;
 264                 dev->mode = NFCSIM_MODE_INITIATOR;
 265                 dev->rf_tech = param;
 266                 break;
 267
 268         case NFC_DIGITAL_CONFIG_FRAMING:
 269                 break;
 270
 271         default:
 272                 NFCSIM_ERR(dev, "Invalid configuration type: %d\n", type);
 273                 return -EINVAL;
 274         }
 275
 276         return 0;
 277 }
 278
 279 static int nfcsim_in_send_cmd(struct nfc_digital_dev *ddev,
 280                                struct sk_buff *skb, u16 timeout,
 281                                nfc_digital_cmd_complete_t cb, void *arg)
 282 {
 283         return nfcsim_send(ddev, skb, timeout, cb, arg);
 284 }
 285
 286 static int nfcsim_tg_configure_hw(struct nfc_digital_dev *ddev,
 287                                           int type, int param)
 288 {
 289         struct nfcsim *dev = nfc_digital_get_drvdata(ddev);
 290
 291         switch (type) {
 292         case NFC_DIGITAL_CONFIG_RF_TECH:
 293                 dev->up = true;
 294                 dev->mode = NFCSIM_MODE_TARGET;
 295                 dev->rf_tech = param;
 296                 break;
 297
 298         case NFC_DIGITAL_CONFIG_FRAMING:
 299                 break;
 300
 301         default:
 302                 NFCSIM_ERR(dev, "Invalid configuration type: %d\n", type);
 303                 return -EINVAL;
 304         }
 305
 306         return 0;
 307 }
 308
 309 static int nfcsim_tg_send_cmd(struct nfc_digital_dev *ddev,
 310                                struct sk_buff *skb, u16 timeout,
 311                                nfc_digital_cmd_complete_t cb, void *arg)
 312 {
 313         return nfcsim_send(ddev, skb, timeout, cb, arg);
 314 }
 315
 316 static int nfcsim_tg_listen(struct nfc_digital_dev *ddev, u16 timeout,
 317                             nfc_digital_cmd_complete_t cb, void *arg)
 318 {
 319         return nfcsim_send(ddev, NULL, timeout, cb, arg);
 320 }
 321
 322 static const struct nfc_digital_ops nfcsim_digital_ops = {
 323         .in_configure_hw = nfcsim_in_configure_hw,
 324         .in_send_cmd = nfcsim_in_send_cmd,
 325
 326         .tg_listen = nfcsim_tg_listen,
 327         .tg_configure_hw = nfcsim_tg_configure_hw,
 328         .tg_send_cmd = nfcsim_tg_send_cmd,
 329
 330         .abort_cmd = nfcsim_abort_cmd,
 331         .switch_rf = nfcsim_switch_rf,
 332 };
 333
 334 static struct dentry *nfcsim_debugfs_root;
 335
 336 static void nfcsim_debugfs_init(void)
 337 {
 338         nfcsim_debugfs_root = debugfs_create_dir("nfcsim", NULL);
 339
 340         if (!nfcsim_debugfs_root)
 341                 pr_err("Could not create debugfs entry\n");
 342
 343 }
 344
 345 static void nfcsim_debugfs_remove(void)
 346 {
 347         debugfs_remove_recursive(nfcsim_debugfs_root);
 348 }
 349
 350 static void nfcsim_debugfs_init_dev(struct nfcsim *dev)
 351 {
 352         struct dentry *dev_dir;
 353         char devname[5]; /* nfcX\0 */
 354         u32 idx;
 355         int n;
 356
 357         if (!nfcsim_debugfs_root) {
 358                 NFCSIM_ERR(dev, "nfcsim debugfs not initialized\n");
 359                 return;
 360         }
 361
 362         idx = dev->nfc_digital_dev->nfc_dev->idx;
 363         n = snprintf(devname, sizeof(devname), "nfc%d", idx);
 364         if (n >= sizeof(devname)) {
 365                 NFCSIM_ERR(dev, "Could not compute dev name for dev %d\n", idx);
 366                 return;
 367         }
 368
 369         dev_dir = debugfs_create_dir(devname, nfcsim_debugfs_root);
 370
 371         debugfs_create_u8("dropframe", 0664, dev_dir, &dev->dropframe);
 372 }
 373
 374 static struct nfcsim *nfcsim_device_new(struct nfcsim_link *link_in,
 375                                         struct nfcsim_link *link_out)
 376 {
 377         struct nfcsim *dev;
 378         int rc;
 379
 380         dev = kzalloc(sizeof(struct nfcsim), GFP_KERNEL);
 381         if (!dev)
 382                 return ERR_PTR(-ENOMEM);
 383
 384         INIT_DELAYED_WORK(&dev->send_work, nfcsim_send_wq);
 385         INIT_WORK(&dev->recv_work, nfcsim_recv_wq);
 386
 387         dev->nfc_digital_dev =
 388                         nfc_digital_allocate_device(&nfcsim_digital_ops,
 389                                                     NFC_PROTO_NFC_DEP_MASK,
 390                                                     NFCSIM_CAPABILITIES,
 391                                                     0, 0);
 392         if (!dev->nfc_digital_dev) {
 393                 kfree(dev);
 394                 return ERR_PTR(-ENOMEM);
 395         }
 396
 397         nfc_digital_set_drvdata(dev->nfc_digital_dev, dev);
 398
 399         dev->link_in = link_in;
 400         dev->link_out = link_out;
 401
 402         rc = nfc_digital_register_device(dev->nfc_digital_dev);
 403         if (rc) {
 404                 pr_err("Could not register digital device (%d)\n", rc);
 405                 nfc_digital_free_device(dev->nfc_digital_dev);
 406                 kfree(dev);
 407
 408                 return ERR_PTR(rc);
 409         }
 410
 411         nfcsim_debugfs_init_dev(dev);
 412
 413         return dev;
 414 }
 415
 416 static void nfcsim_device_free(struct nfcsim *dev)
 417 {
 418         nfc_digital_unregister_device(dev->nfc_digital_dev);
 419
 420         dev->up = false;
 421
 422         nfcsim_link_shutdown(dev->link_in);
 423
 424         cancel_delayed_work_sync(&dev->send_work);
 425         cancel_work_sync(&dev->recv_work);
 426
 427         nfc_digital_free_device(dev->nfc_digital_dev);
 428
 429         kfree(dev);
 430 }
 431
 432 static struct nfcsim *dev0;
 433 static struct nfcsim *dev1;
 434
 435 static int __init nfcsim_init(void)
 436 {
 437         struct nfcsim_link *link0, *link1;
 438         int rc;
 439
 440         link0 = nfcsim_link_new();
 441         link1 = nfcsim_link_new();
 442         if (!link0 || !link1) {
 443                 rc = -ENOMEM;
 444                 goto exit_err;
 445         }
 446
 447         nfcsim_debugfs_init();
 448
 449         dev0 = nfcsim_device_new(link0, link1);
 450         if (IS_ERR(dev0)) {
 451                 rc = PTR_ERR(dev0);
 452                 goto exit_err;
 453         }
 454
 455         dev1 = nfcsim_device_new(link1, link0);
 456         if (IS_ERR(dev1)) {
 457                 nfcsim_device_free(dev0);
 458
 459                 rc = PTR_ERR(dev1);
 460                 goto exit_err;
 461         }
 462
 463         pr_info("nfcsim " NFCSIM_VERSION " initialized\n");
 464
 465         return 0;
 466
 467 exit_err:
 468         pr_err("Failed to initialize nfcsim driver (%d)\n", rc);
 469
 470         if (link0)
 471                 nfcsim_link_free(link0);
 472         if (link1)
 473                 nfcsim_link_free(link1);
 474
 475         return rc;
 476 }
 477
 478 static void __exit nfcsim_exit(void)
 479 {
 480         struct nfcsim_link *link0, *link1;
 481
 482         link0 = dev0->link_in;
 483         link1 = dev0->link_out;
 484
 485         nfcsim_device_free(dev0);
 486         nfcsim_device_free(dev1);
 487
 488         nfcsim_link_free(link0);
 489         nfcsim_link_free(link1);
 490
 491         nfcsim_debugfs_remove();
 492 }
 493
 494 module_init(nfcsim_init);
 495 module_exit(nfcsim_exit);
 496
 497 MODULE_DESCRIPTION("NFCSim driver ver " NFCSIM_VERSION);
 498 MODULE_VERSION(NFCSIM_VERSION);
 499 MODULE_LICENSE("GPL");