net/nfc/core.c

   1 /*
   2  * Copyright (C) 2011 Instituto Nokia de Tecnologia
   3  *
   4  * Authors:
   5  *    Lauro Ramos Venancio <lauro.venancio@openbossa.org>
   6  *    Aloisio Almeida Jr <aloisio.almeida@openbossa.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the
  20  * Free Software Foundation, Inc.,
  21  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  22  */
  23
  24 #define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
  25
  26 #include <linux/init.h>
  27 #include <linux/kernel.h>
  28 #include <linux/module.h>
  29 #include <linux/slab.h>
  30 #include <linux/nfc.h>
  31
  32 #include "nfc.h"
  33
  34 #define VERSION "0.1"
  35
  36 #define NFC_CHECK_PRES_FREQ_MS  2000
  37
  38 int nfc_devlist_generation;
  39 DEFINE_MUTEX(nfc_devlist_mutex);
  40
  41 /**
  42  * nfc_dev_up - turn on the NFC device
  43  *
  44  * @dev: The nfc device to be turned on
  45  *
  46  * The device remains up until the nfc_dev_down function is called.
  47  */
  48 int nfc_dev_up(struct nfc_dev *dev)
  49 {
  50         int rc = 0;
  51
  52         pr_debug("dev_name=%s\n", dev_name(&dev->dev));
  53
  54         device_lock(&dev->dev);
  55
  56         if (!device_is_registered(&dev->dev)) {
  57                 rc = -ENODEV;
  58                 goto error;
  59         }
  60
  61         if (dev->dev_up) {
  62                 rc = -EALREADY;
  63                 goto error;
  64         }
  65
  66         if (dev->ops->dev_up)
  67                 rc = dev->ops->dev_up(dev);
  68
  69         if (!rc)
  70                 dev->dev_up = true;
  71
  72 error:
  73         device_unlock(&dev->dev);
  74         return rc;
  75 }
  76
  77 /**
  78  * nfc_dev_down - turn off the NFC device
  79  *
  80  * @dev: The nfc device to be turned off
  81  */
  82 int nfc_dev_down(struct nfc_dev *dev)
  83 {
  84         int rc = 0;
  85
  86         pr_debug("dev_name=%s\n", dev_name(&dev->dev));
  87
  88         device_lock(&dev->dev);
  89
  90         if (!device_is_registered(&dev->dev)) {
  91                 rc = -ENODEV;
  92                 goto error;
  93         }
  94
  95         if (!dev->dev_up) {
  96                 rc = -EALREADY;
  97                 goto error;
  98         }
  99
 100         if (dev->polling || dev->active_target) {
 101                 rc = -EBUSY;
 102                 goto error;
 103         }
 104
 105         if (dev->ops->dev_down)
 106                 dev->ops->dev_down(dev);
 107
 108         dev->dev_up = false;
 109
 110 error:
 111         device_unlock(&dev->dev);
 112         return rc;
 113 }
 114
 115 /**
 116  * nfc_start_poll - start polling for nfc targets
 117  *
 118  * @dev: The nfc device that must start polling
 119  * @protocols: bitset of nfc protocols that must be used for polling
 120  *
 121  * The device remains polling for targets until a target is found or
 122  * the nfc_stop_poll function is called.
 123  */
 124 int nfc_start_poll(struct nfc_dev *dev, u32 protocols)
 125 {
 126         int rc;
 127
 128         pr_debug("dev_name=%s protocols=0x%x\n",
 129                  dev_name(&dev->dev), protocols);
 130
 131         if (!protocols)
 132                 return -EINVAL;
 133
 134         device_lock(&dev->dev);
 135
 136         if (!device_is_registered(&dev->dev)) {
 137                 rc = -ENODEV;
 138                 goto error;
 139         }
 140
 141         if (dev->polling) {
 142                 rc = -EBUSY;
 143                 goto error;
 144         }
 145
 146         rc = dev->ops->start_poll(dev, protocols);
 147         if (!rc)
 148                 dev->polling = true;
 149
 150 error:
 151         device_unlock(&dev->dev);
 152         return rc;
 153 }
 154
 155 /**
 156  * nfc_stop_poll - stop polling for nfc targets
 157  *
 158  * @dev: The nfc device that must stop polling
 159  */
 160 int nfc_stop_poll(struct nfc_dev *dev)
 161 {
 162         int rc = 0;
 163
 164         pr_debug("dev_name=%s\n", dev_name(&dev->dev));
 165
 166         device_lock(&dev->dev);
 167
 168         if (!device_is_registered(&dev->dev)) {
 169                 rc = -ENODEV;
 170                 goto error;
 171         }
 172
 173         if (!dev->polling) {
 174                 rc = -EINVAL;
 175                 goto error;
 176         }
 177
 178         dev->ops->stop_poll(dev);
 179         dev->polling = false;
 180
 181 error:
 182         device_unlock(&dev->dev);
 183         return rc;
 184 }
 185
 186 static struct nfc_target *nfc_find_target(struct nfc_dev *dev, u32 target_idx)
 187 {
 188         int i;
 189
 190         if (dev->n_targets == 0)
 191                 return NULL;
 192
 193         for (i = 0; i < dev->n_targets ; i++) {
 194                 if (dev->targets[i].idx == target_idx)
 195                         return &dev->targets[i];
 196         }
 197
 198         return NULL;
 199 }
 200
 201 int nfc_dep_link_up(struct nfc_dev *dev, int target_index, u8 comm_mode)
 202 {
 203         int rc = 0;
 204         u8 *gb;
 205         size_t gb_len;
 206         struct nfc_target *target;
 207
 208         pr_debug("dev_name=%s comm %d\n", dev_name(&dev->dev), comm_mode);
 209
 210         if (!dev->ops->dep_link_up)
 211                 return -EOPNOTSUPP;
 212
 213         device_lock(&dev->dev);
 214
 215         if (!device_is_registered(&dev->dev)) {
 216                 rc = -ENODEV;
 217                 goto error;
 218         }
 219
 220         if (dev->dep_link_up == true) {
 221                 rc = -EALREADY;
 222                 goto error;
 223         }
 224
 225         gb = nfc_llcp_general_bytes(dev, &gb_len);
 226         if (gb_len > NFC_MAX_GT_LEN) {
 227                 rc = -EINVAL;
 228                 goto error;
 229         }
 230
 231         target = nfc_find_target(dev, target_index);
 232         if (target == NULL) {
 233                 rc = -ENOTCONN;
 234                 goto error;
 235         }
 236
 237         rc = dev->ops->dep_link_up(dev, target, comm_mode, gb, gb_len);
 238         if (!rc)
 239                 dev->active_target = target;
 240
 241 error:
 242         device_unlock(&dev->dev);
 243         return rc;
 244 }
 245
 246 int nfc_dep_link_down(struct nfc_dev *dev)
 247 {
 248         int rc = 0;
 249
 250         pr_debug("dev_name=%s\n", dev_name(&dev->dev));
 251
 252         if (!dev->ops->dep_link_down)
 253                 return -EOPNOTSUPP;
 254
 255         device_lock(&dev->dev);
 256
 257         if (!device_is_registered(&dev->dev)) {
 258                 rc = -ENODEV;
 259                 goto error;
 260         }
 261
 262         if (dev->dep_link_up == false) {
 263                 rc = -EALREADY;
 264                 goto error;
 265         }
 266
 267         if (dev->dep_rf_mode == NFC_RF_TARGET) {
 268                 rc = -EOPNOTSUPP;
 269                 goto error;
 270         }
 271
 272         rc = dev->ops->dep_link_down(dev);
 273         if (!rc) {
 274                 dev->dep_link_up = false;
 275                 dev->active_target = NULL;
 276                 nfc_llcp_mac_is_down(dev);
 277                 nfc_genl_dep_link_down_event(dev);
 278         }
 279
 280 error:
 281         device_unlock(&dev->dev);
 282         return rc;
 283 }
 284
 285 int nfc_dep_link_is_up(struct nfc_dev *dev, u32 target_idx,
 286                        u8 comm_mode, u8 rf_mode)
 287 {
 288         dev->dep_link_up = true;
 289         dev->dep_rf_mode = rf_mode;
 290
 291         nfc_llcp_mac_is_up(dev, target_idx, comm_mode, rf_mode);
 292
 293         return nfc_genl_dep_link_up_event(dev, target_idx, comm_mode, rf_mode);
 294 }
 295 EXPORT_SYMBOL(nfc_dep_link_is_up);
 296
 297 /**
 298  * nfc_activate_target - prepare the target for data exchange
 299  *
 300  * @dev: The nfc device that found the target
 301  * @target_idx: index of the target that must be activated
 302  * @protocol: nfc protocol that will be used for data exchange
 303  */
 304 int nfc_activate_target(struct nfc_dev *dev, u32 target_idx, u32 protocol)
 305 {
 306         int rc;
 307         struct nfc_target *target;
 308
 309         pr_debug("dev_name=%s target_idx=%u protocol=%u\n",
 310                  dev_name(&dev->dev), target_idx, protocol);
 311
 312         device_lock(&dev->dev);
 313
 314         if (!device_is_registered(&dev->dev)) {
 315                 rc = -ENODEV;
 316                 goto error;
 317         }
 318
 319         if (dev->active_target) {
 320                 rc = -EBUSY;
 321                 goto error;
 322         }
 323
 324         target = nfc_find_target(dev, target_idx);
 325         if (target == NULL) {
 326                 rc = -ENOTCONN;
 327                 goto error;
 328         }
 329
 330         rc = dev->ops->activate_target(dev, target, protocol);
 331         if (!rc) {
 332                 dev->active_target = target;
 333
 334                 if (dev->ops->check_presence)
 335                         mod_timer(&dev->check_pres_timer, jiffies +
 336                                   msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
 337         }
 338
 339 error:
 340         device_unlock(&dev->dev);
 341         return rc;
 342 }
 343
 344 /**
 345  * nfc_deactivate_target - deactivate a nfc target
 346  *
 347  * @dev: The nfc device that found the target
 348  * @target_idx: index of the target that must be deactivated
 349  */
 350 int nfc_deactivate_target(struct nfc_dev *dev, u32 target_idx)
 351 {
 352         int rc = 0;
 353
 354         pr_debug("dev_name=%s target_idx=%u\n",
 355                  dev_name(&dev->dev), target_idx);
 356
 357         device_lock(&dev->dev);
 358
 359         if (!device_is_registered(&dev->dev)) {
 360                 rc = -ENODEV;
 361                 goto error;
 362         }
 363
 364         if (dev->active_target == NULL) {
 365                 rc = -ENOTCONN;
 366                 goto error;
 367         }
 368
 369         if (dev->active_target->idx != target_idx) {
 370                 rc = -ENOTCONN;
 371                 goto error;
 372         }
 373
 374         if (dev->ops->check_presence)
 375                 del_timer_sync(&dev->check_pres_timer);
 376
 377         dev->ops->deactivate_target(dev, dev->active_target);
 378         dev->active_target = NULL;
 379
 380 error:
 381         device_unlock(&dev->dev);
 382         return rc;
 383 }
 384
 385 /**
 386  * nfc_data_exchange - transceive data
 387  *
 388  * @dev: The nfc device that found the target
 389  * @target_idx: index of the target
 390  * @skb: data to be sent
 391  * @cb: callback called when the response is received
 392  * @cb_context: parameter for the callback function
 393  *
 394  * The user must wait for the callback before calling this function again.
 395  */
 396 int nfc_data_exchange(struct nfc_dev *dev, u32 target_idx, struct sk_buff *skb,
 397                       data_exchange_cb_t cb, void *cb_context)
 398 {
 399         int rc;
 400
 401         pr_debug("dev_name=%s target_idx=%u skb->len=%u\n",
 402                  dev_name(&dev->dev), target_idx, skb->len);
 403
 404         device_lock(&dev->dev);
 405
 406         if (!device_is_registered(&dev->dev)) {
 407                 rc = -ENODEV;
 408                 kfree_skb(skb);
 409                 goto error;
 410         }
 411
 412         if (dev->active_target == NULL) {
 413                 rc = -ENOTCONN;
 414                 kfree_skb(skb);
 415                 goto error;
 416         }
 417
 418         if (dev->active_target->idx != target_idx) {
 419                 rc = -EADDRNOTAVAIL;
 420                 kfree_skb(skb);
 421                 goto error;
 422         }
 423
 424         if (dev->ops->check_presence)
 425                 del_timer_sync(&dev->check_pres_timer);
 426
 427         rc = dev->ops->data_exchange(dev, dev->active_target, skb, cb,
 428                                      cb_context);
 429
 430         if (!rc && dev->ops->check_presence)
 431                 mod_timer(&dev->check_pres_timer, jiffies +
 432                           msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
 433
 434 error:
 435         device_unlock(&dev->dev);
 436         return rc;
 437 }
 438
 439 int nfc_set_remote_general_bytes(struct nfc_dev *dev, u8 *gb, u8 gb_len)
 440 {
 441         pr_debug("dev_name=%s gb_len=%d\n", dev_name(&dev->dev), gb_len);
 442
 443         if (gb_len > NFC_MAX_GT_LEN)
 444                 return -EINVAL;
 445
 446         return nfc_llcp_set_remote_gb(dev, gb, gb_len);
 447 }
 448 EXPORT_SYMBOL(nfc_set_remote_general_bytes);
 449
 450 /**
 451  * nfc_alloc_send_skb - allocate a skb for data exchange responses
 452  *
 453  * @size: size to allocate
 454  * @gfp: gfp flags
 455  */
 456 struct sk_buff *nfc_alloc_send_skb(struct nfc_dev *dev, struct sock *sk,
 457                                    unsigned int flags, unsigned int size,
 458                                    unsigned int *err)
 459 {
 460         struct sk_buff *skb;
 461         unsigned int total_size;
 462
 463         total_size = size +
 464                 dev->tx_headroom + dev->tx_tailroom + NFC_HEADER_SIZE;
 465
 466         skb = sock_alloc_send_skb(sk, total_size, flags & MSG_DONTWAIT, err);
 467         if (skb)
 468                 skb_reserve(skb, dev->tx_headroom + NFC_HEADER_SIZE);
 469
 470         return skb;
 471 }
 472
 473 /**
 474  * nfc_alloc_recv_skb - allocate a skb for data exchange responses
 475  *
 476  * @size: size to allocate
 477  * @gfp: gfp flags
 478  */
 479 struct sk_buff *nfc_alloc_recv_skb(unsigned int size, gfp_t gfp)
 480 {
 481         struct sk_buff *skb;
 482         unsigned int total_size;
 483
 484         total_size = size + 1;
 485         skb = alloc_skb(total_size, gfp);
 486
 487         if (skb)
 488                 skb_reserve(skb, 1);
 489
 490         return skb;
 491 }
 492 EXPORT_SYMBOL(nfc_alloc_recv_skb);
 493
 494 /**
 495  * nfc_targets_found - inform that targets were found
 496  *
 497  * @dev: The nfc device that found the targets
 498  * @targets: array of nfc targets found
 499  * @ntargets: targets array size
 500  *
 501  * The device driver must call this function when one or many nfc targets
 502  * are found. After calling this function, the device driver must stop
 503  * polling for targets.
 504  * IMPORTANT: this function must not be called from an atomic context.
 505  * In addition, it must also not be called from a context that would prevent
 506  * the NFC Core to call other nfc ops entry point concurrently.
 507  */
 508 int nfc_targets_found(struct nfc_dev *dev,
 509                       struct nfc_target *targets, int n_targets)
 510 {
 511         int i;
 512
 513         pr_debug("dev_name=%s n_targets=%d\n", dev_name(&dev->dev), n_targets);
 514
 515         dev->polling = false;
 516
 517         for (i = 0; i < n_targets; i++)
 518                 targets[i].idx = dev->target_next_idx++;
 519
 520         device_lock(&dev->dev);
 521
 522         dev->targets_generation++;
 523
 524         kfree(dev->targets);
 525         dev->targets = kmemdup(targets, n_targets * sizeof(struct nfc_target),
 526                                GFP_ATOMIC);
 527
 528         if (!dev->targets) {
 529                 dev->n_targets = 0;
 530                 device_unlock(&dev->dev);
 531                 return -ENOMEM;
 532         }
 533
 534         dev->n_targets = n_targets;
 535         device_unlock(&dev->dev);
 536
 537         nfc_genl_targets_found(dev);
 538
 539         return 0;
 540 }
 541 EXPORT_SYMBOL(nfc_targets_found);
 542
 543 /**
 544  * nfc_target_lost - inform that an activated target went out of field
 545  *
 546  * @dev: The nfc device that had the activated target in field
 547  * @target_idx: the nfc index of the target
 548  *
 549  * The device driver must call this function when the activated target
 550  * goes out of the field.
 551  * IMPORTANT: this function must not be called from an atomic context.
 552  * In addition, it must also not be called from a context that would prevent
 553  * the NFC Core to call other nfc ops entry point concurrently.
 554  */
 555 int nfc_target_lost(struct nfc_dev *dev, u32 target_idx)
 556 {
 557         struct nfc_target *tg;
 558         int i;
 559
 560         pr_debug("dev_name %s n_target %d\n", dev_name(&dev->dev), target_idx);
 561
 562         device_lock(&dev->dev);
 563
 564         for (i = 0; i < dev->n_targets; i++) {
 565                 tg = &dev->targets[i];
 566                 if (tg->idx == target_idx)
 567                         break;
 568         }
 569
 570         if (i == dev->n_targets) {
 571                 device_unlock(&dev->dev);
 572                 return -EINVAL;
 573         }
 574
 575         dev->targets_generation++;
 576         dev->n_targets--;
 577         dev->active_target = NULL;
 578
 579         if (dev->n_targets) {
 580                 memcpy(&dev->targets[i], &dev->targets[i + 1],
 581                        (dev->n_targets - i) * sizeof(struct nfc_target));
 582         } else {
 583                 kfree(dev->targets);
 584                 dev->targets = NULL;
 585         }
 586
 587         device_unlock(&dev->dev);
 588
 589         nfc_genl_target_lost(dev, target_idx);
 590
 591         return 0;
 592 }
 593 EXPORT_SYMBOL(nfc_target_lost);
 594
 595 static void nfc_release(struct device *d)
 596 {
 597         struct nfc_dev *dev = to_nfc_dev(d);
 598
 599         pr_debug("dev_name=%s\n", dev_name(&dev->dev));
 600
 601         if (dev->ops->check_presence) {
 602                 del_timer_sync(&dev->check_pres_timer);
 603                 destroy_workqueue(dev->check_pres_wq);
 604         }
 605
 606         nfc_genl_data_exit(&dev->genl_data);
 607         kfree(dev->targets);
 608         kfree(dev);
 609 }
 610
 611 static void nfc_check_pres_work(struct work_struct *work)
 612 {
 613         struct nfc_dev *dev = container_of(work, struct nfc_dev,
 614                                            check_pres_work);
 615         int rc;
 616
 617         device_lock(&dev->dev);
 618
 619         if (dev->active_target && timer_pending(&dev->check_pres_timer) == 0) {
 620                 rc = dev->ops->check_presence(dev, dev->active_target);
 621                 if (!rc) {
 622                         mod_timer(&dev->check_pres_timer, jiffies +
 623                                   msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
 624                 } else {
 625                         u32 active_target_idx = dev->active_target->idx;
 626                         device_unlock(&dev->dev);
 627                         nfc_target_lost(dev, active_target_idx);
 628                         return;
 629                 }
 630         }
 631
 632         device_unlock(&dev->dev);
 633 }
 634
 635 static void nfc_check_pres_timeout(unsigned long data)
 636 {
 637         struct nfc_dev *dev = (struct nfc_dev *)data;
 638
 639         queue_work(dev->check_pres_wq, &dev->check_pres_work);
 640 }
 641
 642 struct class nfc_class = {
 643         .name = "nfc",
 644         .dev_release = nfc_release,
 645 };
 646 EXPORT_SYMBOL(nfc_class);
 647
 648 static int match_idx(struct device *d, void *data)
 649 {
 650         struct nfc_dev *dev = to_nfc_dev(d);
 651         unsigned int *idx = data;
 652
 653         return dev->idx == *idx;
 654 }
 655
 656 struct nfc_dev *nfc_get_device(unsigned int idx)
 657 {
 658         struct device *d;
 659
 660         d = class_find_device(&nfc_class, NULL, &idx, match_idx);
 661         if (!d)
 662                 return NULL;
 663
 664         return to_nfc_dev(d);
 665 }
 666
 667 /**
 668  * nfc_allocate_device - allocate a new nfc device
 669  *
 670  * @ops: device operations
 671  * @supported_protocols: NFC protocols supported by the device
 672  */
 673 struct nfc_dev *nfc_allocate_device(struct nfc_ops *ops,
 674                                     u32 supported_protocols,
 675                                     int tx_headroom, int tx_tailroom)
 676 {
 677         static atomic_t dev_no = ATOMIC_INIT(0);
 678         struct nfc_dev *dev;
 679
 680         if (!ops->start_poll || !ops->stop_poll || !ops->activate_target ||
 681             !ops->deactivate_target || !ops->data_exchange)
 682                 return NULL;
 683
 684         if (!supported_protocols)
 685                 return NULL;
 686
 687         dev = kzalloc(sizeof(struct nfc_dev), GFP_KERNEL);
 688         if (!dev)
 689                 return NULL;
 690
 691         dev->dev.class = &nfc_class;
 692         dev->idx = atomic_inc_return(&dev_no) - 1;
 693         dev_set_name(&dev->dev, "nfc%d", dev->idx);
 694         device_initialize(&dev->dev);
 695
 696         dev->ops = ops;
 697         dev->supported_protocols = supported_protocols;
 698         dev->tx_headroom = tx_headroom;
 699         dev->tx_tailroom = tx_tailroom;
 700
 701         nfc_genl_data_init(&dev->genl_data);
 702
 703
 704         /* first generation must not be 0 */
 705         dev->targets_generation = 1;
 706
 707         if (ops->check_presence) {
 708                 char name[32];
 709                 init_timer(&dev->check_pres_timer);
 710                 dev->check_pres_timer.data = (unsigned long)dev;
 711                 dev->check_pres_timer.function = nfc_check_pres_timeout;
 712
 713                 INIT_WORK(&dev->check_pres_work, nfc_check_pres_work);
 714                 snprintf(name, sizeof(name), "nfc%d_check_pres_wq", dev->idx);
 715                 dev->check_pres_wq = alloc_workqueue(name, WQ_NON_REENTRANT |
 716                                                      WQ_UNBOUND |
 717                                                      WQ_MEM_RECLAIM, 1);
 718                 if (dev->check_pres_wq == NULL) {
 719                         kfree(dev);
 720                         return NULL;
 721                 }
 722         }
 723
 724         return dev;
 725 }
 726 EXPORT_SYMBOL(nfc_allocate_device);
 727
 728 /**
 729  * nfc_register_device - register a nfc device in the nfc subsystem
 730  *
 731  * @dev: The nfc device to register
 732  */
 733 int nfc_register_device(struct nfc_dev *dev)
 734 {
 735         int rc;
 736
 737         pr_debug("dev_name=%s\n", dev_name(&dev->dev));
 738
 739         mutex_lock(&nfc_devlist_mutex);
 740         nfc_devlist_generation++;
 741         rc = device_add(&dev->dev);
 742         mutex_unlock(&nfc_devlist_mutex);
 743
 744         if (rc < 0)
 745                 return rc;
 746
 747         rc = nfc_llcp_register_device(dev);
 748         if (rc)
 749                 pr_err("Could not register llcp device\n");
 750
 751         rc = nfc_genl_device_added(dev);
 752         if (rc)
 753                 pr_debug("The userspace won't be notified that the device %s was added\n",
 754                          dev_name(&dev->dev));
 755
 756         return 0;
 757 }
 758 EXPORT_SYMBOL(nfc_register_device);
 759
 760 /**
 761  * nfc_unregister_device - unregister a nfc device in the nfc subsystem
 762  *
 763  * @dev: The nfc device to unregister
 764  */
 765 void nfc_unregister_device(struct nfc_dev *dev)
 766 {
 767         int rc;
 768
 769         pr_debug("dev_name=%s\n", dev_name(&dev->dev));
 770
 771         mutex_lock(&nfc_devlist_mutex);
 772         nfc_devlist_generation++;
 773
 774         /* lock to avoid unregistering a device while an operation
 775            is in progress */
 776         device_lock(&dev->dev);
 777         device_del(&dev->dev);
 778         device_unlock(&dev->dev);
 779
 780         mutex_unlock(&nfc_devlist_mutex);
 781
 782         nfc_llcp_unregister_device(dev);
 783
 784         rc = nfc_genl_device_removed(dev);
 785         if (rc)
 786                 pr_debug("The userspace won't be notified that the device %s was removed\n",
 787                          dev_name(&dev->dev));
 788
 789 }
 790 EXPORT_SYMBOL(nfc_unregister_device);
 791
 792 static int __init nfc_init(void)
 793 {
 794         int rc;
 795
 796         pr_info("NFC Core ver %s\n", VERSION);
 797
 798         rc = class_register(&nfc_class);
 799         if (rc)
 800                 return rc;
 801
 802         rc = nfc_genl_init();
 803         if (rc)
 804                 goto err_genl;
 805
 806         /* the first generation must not be 0 */
 807         nfc_devlist_generation = 1;
 808
 809         rc = rawsock_init();
 810         if (rc)
 811                 goto err_rawsock;
 812
 813         rc = nfc_llcp_init();
 814         if (rc)
 815                 goto err_llcp_sock;
 816
 817         rc = af_nfc_init();
 818         if (rc)
 819                 goto err_af_nfc;
 820
 821         return 0;
 822
 823 err_af_nfc:
 824         nfc_llcp_exit();
 825 err_llcp_sock:
 826         rawsock_exit();
 827 err_rawsock:
 828         nfc_genl_exit();
 829 err_genl:
 830         class_unregister(&nfc_class);
 831         return rc;
 832 }
 833
 834 static void __exit nfc_exit(void)
 835 {
 836         af_nfc_exit();
 837         nfc_llcp_exit();
 838         rawsock_exit();
 839         nfc_genl_exit();
 840         class_unregister(&nfc_class);
 841 }
 842
 843 subsys_initcall(nfc_init);
 844 module_exit(nfc_exit);
 845
 846 MODULE_AUTHOR("Lauro Ramos Venancio <lauro.venancio@openbossa.org>");
 847 MODULE_DESCRIPTION("NFC Core ver " VERSION);
 848 MODULE_VERSION(VERSION);
 849 MODULE_LICENSE("GPL");