xref: /linux/net/nfc/core.c (revision 25aee3debe0464f6c680173041fa3de30ec9ff54)
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 <net/genetlink.h>
33 
34 #include "nfc.h"
35 
36 #define VERSION "0.1"
37 
38 #define NFC_CHECK_PRES_FREQ_MS	2000
39 
40 int nfc_devlist_generation;
41 DEFINE_MUTEX(nfc_devlist_mutex);
42 
43 /**
44  * nfc_dev_up - turn on the NFC device
45  *
46  * @dev: The nfc device to be turned on
47  *
48  * The device remains up until the nfc_dev_down function is called.
49  */
50 int nfc_dev_up(struct nfc_dev *dev)
51 {
52 	int rc = 0;
53 
54 	pr_debug("dev_name=%s\n", dev_name(&dev->dev));
55 
56 	device_lock(&dev->dev);
57 
58 	if (!device_is_registered(&dev->dev)) {
59 		rc = -ENODEV;
60 		goto error;
61 	}
62 
63 	if (dev->dev_up) {
64 		rc = -EALREADY;
65 		goto error;
66 	}
67 
68 	if (dev->ops->dev_up)
69 		rc = dev->ops->dev_up(dev);
70 
71 	if (!rc)
72 		dev->dev_up = true;
73 
74 error:
75 	device_unlock(&dev->dev);
76 	return rc;
77 }
78 
79 /**
80  * nfc_dev_down - turn off the NFC device
81  *
82  * @dev: The nfc device to be turned off
83  */
84 int nfc_dev_down(struct nfc_dev *dev)
85 {
86 	int rc = 0;
87 
88 	pr_debug("dev_name=%s\n", dev_name(&dev->dev));
89 
90 	device_lock(&dev->dev);
91 
92 	if (!device_is_registered(&dev->dev)) {
93 		rc = -ENODEV;
94 		goto error;
95 	}
96 
97 	if (!dev->dev_up) {
98 		rc = -EALREADY;
99 		goto error;
100 	}
101 
102 	if (dev->polling || dev->active_target) {
103 		rc = -EBUSY;
104 		goto error;
105 	}
106 
107 	if (dev->ops->dev_down)
108 		dev->ops->dev_down(dev);
109 
110 	dev->dev_up = false;
111 
112 error:
113 	device_unlock(&dev->dev);
114 	return rc;
115 }
116 
117 /**
118  * nfc_start_poll - start polling for nfc targets
119  *
120  * @dev: The nfc device that must start polling
121  * @protocols: bitset of nfc protocols that must be used for polling
122  *
123  * The device remains polling for targets until a target is found or
124  * the nfc_stop_poll function is called.
125  */
126 int nfc_start_poll(struct nfc_dev *dev, u32 im_protocols, u32 tm_protocols)
127 {
128 	int rc;
129 
130 	pr_debug("dev_name %s initiator protocols 0x%x target protocols 0x%x\n",
131 		 dev_name(&dev->dev), im_protocols, tm_protocols);
132 
133 	if (!im_protocols && !tm_protocols)
134 		return -EINVAL;
135 
136 	device_lock(&dev->dev);
137 
138 	if (!device_is_registered(&dev->dev)) {
139 		rc = -ENODEV;
140 		goto error;
141 	}
142 
143 	if (dev->polling) {
144 		rc = -EBUSY;
145 		goto error;
146 	}
147 
148 	rc = dev->ops->start_poll(dev, im_protocols, tm_protocols);
149 	if (!rc) {
150 		dev->polling = true;
151 		dev->rf_mode = NFC_RF_NONE;
152 	}
153 
154 error:
155 	device_unlock(&dev->dev);
156 	return rc;
157 }
158 
159 /**
160  * nfc_stop_poll - stop polling for nfc targets
161  *
162  * @dev: The nfc device that must stop polling
163  */
164 int nfc_stop_poll(struct nfc_dev *dev)
165 {
166 	int rc = 0;
167 
168 	pr_debug("dev_name=%s\n", dev_name(&dev->dev));
169 
170 	device_lock(&dev->dev);
171 
172 	if (!device_is_registered(&dev->dev)) {
173 		rc = -ENODEV;
174 		goto error;
175 	}
176 
177 	if (!dev->polling) {
178 		rc = -EINVAL;
179 		goto error;
180 	}
181 
182 	dev->ops->stop_poll(dev);
183 	dev->polling = false;
184 
185 error:
186 	device_unlock(&dev->dev);
187 	return rc;
188 }
189 
190 static struct nfc_target *nfc_find_target(struct nfc_dev *dev, u32 target_idx)
191 {
192 	int i;
193 
194 	if (dev->n_targets == 0)
195 		return NULL;
196 
197 	for (i = 0; i < dev->n_targets ; i++) {
198 		if (dev->targets[i].idx == target_idx)
199 			return &dev->targets[i];
200 	}
201 
202 	return NULL;
203 }
204 
205 int nfc_dep_link_up(struct nfc_dev *dev, int target_index, u8 comm_mode)
206 {
207 	int rc = 0;
208 	u8 *gb;
209 	size_t gb_len;
210 	struct nfc_target *target;
211 
212 	pr_debug("dev_name=%s comm %d\n", dev_name(&dev->dev), comm_mode);
213 
214 	if (!dev->ops->dep_link_up)
215 		return -EOPNOTSUPP;
216 
217 	device_lock(&dev->dev);
218 
219 	if (!device_is_registered(&dev->dev)) {
220 		rc = -ENODEV;
221 		goto error;
222 	}
223 
224 	if (dev->dep_link_up == true) {
225 		rc = -EALREADY;
226 		goto error;
227 	}
228 
229 	gb = nfc_llcp_general_bytes(dev, &gb_len);
230 	if (gb_len > NFC_MAX_GT_LEN) {
231 		rc = -EINVAL;
232 		goto error;
233 	}
234 
235 	target = nfc_find_target(dev, target_index);
236 	if (target == NULL) {
237 		rc = -ENOTCONN;
238 		goto error;
239 	}
240 
241 	rc = dev->ops->dep_link_up(dev, target, comm_mode, gb, gb_len);
242 	if (!rc) {
243 		dev->active_target = target;
244 		dev->rf_mode = NFC_RF_INITIATOR;
245 	}
246 
247 error:
248 	device_unlock(&dev->dev);
249 	return rc;
250 }
251 
252 int nfc_dep_link_down(struct nfc_dev *dev)
253 {
254 	int rc = 0;
255 
256 	pr_debug("dev_name=%s\n", dev_name(&dev->dev));
257 
258 	if (!dev->ops->dep_link_down)
259 		return -EOPNOTSUPP;
260 
261 	device_lock(&dev->dev);
262 
263 	if (!device_is_registered(&dev->dev)) {
264 		rc = -ENODEV;
265 		goto error;
266 	}
267 
268 	if (dev->dep_link_up == false) {
269 		rc = -EALREADY;
270 		goto error;
271 	}
272 
273 	rc = dev->ops->dep_link_down(dev);
274 	if (!rc) {
275 		dev->dep_link_up = false;
276 		dev->active_target = NULL;
277 		nfc_llcp_mac_is_down(dev);
278 		nfc_genl_dep_link_down_event(dev);
279 	}
280 
281 error:
282 	device_unlock(&dev->dev);
283 	return rc;
284 }
285 
286 int nfc_dep_link_is_up(struct nfc_dev *dev, u32 target_idx,
287 		       u8 comm_mode, u8 rf_mode)
288 {
289 	dev->dep_link_up = true;
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 		dev->rf_mode = NFC_RF_INITIATOR;
334 
335 		if (dev->ops->check_presence)
336 			mod_timer(&dev->check_pres_timer, jiffies +
337 				  msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
338 	}
339 
340 error:
341 	device_unlock(&dev->dev);
342 	return rc;
343 }
344 
345 /**
346  * nfc_deactivate_target - deactivate a nfc target
347  *
348  * @dev: The nfc device that found the target
349  * @target_idx: index of the target that must be deactivated
350  */
351 int nfc_deactivate_target(struct nfc_dev *dev, u32 target_idx)
352 {
353 	int rc = 0;
354 
355 	pr_debug("dev_name=%s target_idx=%u\n",
356 		 dev_name(&dev->dev), target_idx);
357 
358 	device_lock(&dev->dev);
359 
360 	if (!device_is_registered(&dev->dev)) {
361 		rc = -ENODEV;
362 		goto error;
363 	}
364 
365 	if (dev->active_target == NULL) {
366 		rc = -ENOTCONN;
367 		goto error;
368 	}
369 
370 	if (dev->active_target->idx != target_idx) {
371 		rc = -ENOTCONN;
372 		goto error;
373 	}
374 
375 	if (dev->ops->check_presence)
376 		del_timer_sync(&dev->check_pres_timer);
377 
378 	dev->ops->deactivate_target(dev, dev->active_target);
379 	dev->active_target = NULL;
380 
381 error:
382 	device_unlock(&dev->dev);
383 	return rc;
384 }
385 
386 /**
387  * nfc_data_exchange - transceive data
388  *
389  * @dev: The nfc device that found the target
390  * @target_idx: index of the target
391  * @skb: data to be sent
392  * @cb: callback called when the response is received
393  * @cb_context: parameter for the callback function
394  *
395  * The user must wait for the callback before calling this function again.
396  */
397 int nfc_data_exchange(struct nfc_dev *dev, u32 target_idx, struct sk_buff *skb,
398 		      data_exchange_cb_t cb, void *cb_context)
399 {
400 	int rc;
401 
402 	pr_debug("dev_name=%s target_idx=%u skb->len=%u\n",
403 		 dev_name(&dev->dev), target_idx, skb->len);
404 
405 	device_lock(&dev->dev);
406 
407 	if (!device_is_registered(&dev->dev)) {
408 		rc = -ENODEV;
409 		kfree_skb(skb);
410 		goto error;
411 	}
412 
413 	if (dev->rf_mode == NFC_RF_INITIATOR && dev->active_target != NULL) {
414 		if (dev->active_target->idx != target_idx) {
415 			rc = -EADDRNOTAVAIL;
416 			kfree_skb(skb);
417 			goto error;
418 		}
419 
420 		if (dev->ops->check_presence)
421 			del_timer_sync(&dev->check_pres_timer);
422 
423 		rc = dev->ops->im_transceive(dev, dev->active_target, skb, cb,
424 					     cb_context);
425 
426 		if (!rc && dev->ops->check_presence)
427 			mod_timer(&dev->check_pres_timer, jiffies +
428 				  msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
429 	} else if (dev->rf_mode == NFC_RF_TARGET && dev->ops->tm_send != NULL) {
430 		rc = dev->ops->tm_send(dev, skb);
431 	} else {
432 		rc = -ENOTCONN;
433 		kfree_skb(skb);
434 		goto error;
435 	}
436 
437 
438 error:
439 	device_unlock(&dev->dev);
440 	return rc;
441 }
442 
443 int nfc_set_remote_general_bytes(struct nfc_dev *dev, u8 *gb, u8 gb_len)
444 {
445 	pr_debug("dev_name=%s gb_len=%d\n", dev_name(&dev->dev), gb_len);
446 
447 	if (gb_len > NFC_MAX_GT_LEN)
448 		return -EINVAL;
449 
450 	return nfc_llcp_set_remote_gb(dev, gb, gb_len);
451 }
452 EXPORT_SYMBOL(nfc_set_remote_general_bytes);
453 
454 u8 *nfc_get_local_general_bytes(struct nfc_dev *dev, size_t *gb_len)
455 {
456 	pr_debug("dev_name=%s\n", dev_name(&dev->dev));
457 
458 	return nfc_llcp_general_bytes(dev, gb_len);
459 }
460 EXPORT_SYMBOL(nfc_get_local_general_bytes);
461 
462 int nfc_tm_data_received(struct nfc_dev *dev, struct sk_buff *skb)
463 {
464 	/* Only LLCP target mode for now */
465 	if (dev->dep_link_up == false) {
466 		kfree_skb(skb);
467 		return -ENOLINK;
468 	}
469 
470 	return nfc_llcp_data_received(dev, skb);
471 }
472 EXPORT_SYMBOL(nfc_tm_data_received);
473 
474 int nfc_tm_activated(struct nfc_dev *dev, u32 protocol, u8 comm_mode,
475 		     u8 *gb, size_t gb_len)
476 {
477 	int rc;
478 
479 	device_lock(&dev->dev);
480 
481 	dev->polling = false;
482 
483 	if (gb != NULL) {
484 		rc = nfc_set_remote_general_bytes(dev, gb, gb_len);
485 		if (rc < 0)
486 			goto out;
487 	}
488 
489 	dev->rf_mode = NFC_RF_TARGET;
490 
491 	if (protocol == NFC_PROTO_NFC_DEP_MASK)
492 		nfc_dep_link_is_up(dev, 0, comm_mode, NFC_RF_TARGET);
493 
494 	rc = nfc_genl_tm_activated(dev, protocol);
495 
496 out:
497 	device_unlock(&dev->dev);
498 
499 	return rc;
500 }
501 EXPORT_SYMBOL(nfc_tm_activated);
502 
503 int nfc_tm_deactivated(struct nfc_dev *dev)
504 {
505 	dev->dep_link_up = false;
506 
507 	return nfc_genl_tm_deactivated(dev);
508 }
509 EXPORT_SYMBOL(nfc_tm_deactivated);
510 
511 /**
512  * nfc_alloc_send_skb - allocate a skb for data exchange responses
513  *
514  * @size: size to allocate
515  * @gfp: gfp flags
516  */
517 struct sk_buff *nfc_alloc_send_skb(struct nfc_dev *dev, struct sock *sk,
518 				   unsigned int flags, unsigned int size,
519 				   unsigned int *err)
520 {
521 	struct sk_buff *skb;
522 	unsigned int total_size;
523 
524 	total_size = size +
525 		dev->tx_headroom + dev->tx_tailroom + NFC_HEADER_SIZE;
526 
527 	skb = sock_alloc_send_skb(sk, total_size, flags & MSG_DONTWAIT, err);
528 	if (skb)
529 		skb_reserve(skb, dev->tx_headroom + NFC_HEADER_SIZE);
530 
531 	return skb;
532 }
533 
534 /**
535  * nfc_alloc_recv_skb - allocate a skb for data exchange responses
536  *
537  * @size: size to allocate
538  * @gfp: gfp flags
539  */
540 struct sk_buff *nfc_alloc_recv_skb(unsigned int size, gfp_t gfp)
541 {
542 	struct sk_buff *skb;
543 	unsigned int total_size;
544 
545 	total_size = size + 1;
546 	skb = alloc_skb(total_size, gfp);
547 
548 	if (skb)
549 		skb_reserve(skb, 1);
550 
551 	return skb;
552 }
553 EXPORT_SYMBOL(nfc_alloc_recv_skb);
554 
555 /**
556  * nfc_targets_found - inform that targets were found
557  *
558  * @dev: The nfc device that found the targets
559  * @targets: array of nfc targets found
560  * @ntargets: targets array size
561  *
562  * The device driver must call this function when one or many nfc targets
563  * are found. After calling this function, the device driver must stop
564  * polling for targets.
565  * NOTE: This function can be called with targets=NULL and n_targets=0 to
566  * notify a driver error, meaning that the polling operation cannot complete.
567  * IMPORTANT: this function must not be called from an atomic context.
568  * In addition, it must also not be called from a context that would prevent
569  * the NFC Core to call other nfc ops entry point concurrently.
570  */
571 int nfc_targets_found(struct nfc_dev *dev,
572 		      struct nfc_target *targets, int n_targets)
573 {
574 	int i;
575 
576 	pr_debug("dev_name=%s n_targets=%d\n", dev_name(&dev->dev), n_targets);
577 
578 	for (i = 0; i < n_targets; i++)
579 		targets[i].idx = dev->target_next_idx++;
580 
581 	device_lock(&dev->dev);
582 
583 	if (dev->polling == false) {
584 		device_unlock(&dev->dev);
585 		return 0;
586 	}
587 
588 	dev->polling = false;
589 
590 	dev->targets_generation++;
591 
592 	kfree(dev->targets);
593 	dev->targets = NULL;
594 
595 	if (targets) {
596 		dev->targets = kmemdup(targets,
597 				       n_targets * sizeof(struct nfc_target),
598 				       GFP_ATOMIC);
599 
600 		if (!dev->targets) {
601 			dev->n_targets = 0;
602 			device_unlock(&dev->dev);
603 			return -ENOMEM;
604 		}
605 	}
606 
607 	dev->n_targets = n_targets;
608 	device_unlock(&dev->dev);
609 
610 	nfc_genl_targets_found(dev);
611 
612 	return 0;
613 }
614 EXPORT_SYMBOL(nfc_targets_found);
615 
616 /**
617  * nfc_target_lost - inform that an activated target went out of field
618  *
619  * @dev: The nfc device that had the activated target in field
620  * @target_idx: the nfc index of the target
621  *
622  * The device driver must call this function when the activated target
623  * goes out of the field.
624  * IMPORTANT: this function must not be called from an atomic context.
625  * In addition, it must also not be called from a context that would prevent
626  * the NFC Core to call other nfc ops entry point concurrently.
627  */
628 int nfc_target_lost(struct nfc_dev *dev, u32 target_idx)
629 {
630 	struct nfc_target *tg;
631 	int i;
632 
633 	pr_debug("dev_name %s n_target %d\n", dev_name(&dev->dev), target_idx);
634 
635 	device_lock(&dev->dev);
636 
637 	for (i = 0; i < dev->n_targets; i++) {
638 		tg = &dev->targets[i];
639 		if (tg->idx == target_idx)
640 			break;
641 	}
642 
643 	if (i == dev->n_targets) {
644 		device_unlock(&dev->dev);
645 		return -EINVAL;
646 	}
647 
648 	dev->targets_generation++;
649 	dev->n_targets--;
650 	dev->active_target = NULL;
651 
652 	if (dev->n_targets) {
653 		memcpy(&dev->targets[i], &dev->targets[i + 1],
654 		       (dev->n_targets - i) * sizeof(struct nfc_target));
655 	} else {
656 		kfree(dev->targets);
657 		dev->targets = NULL;
658 	}
659 
660 	device_unlock(&dev->dev);
661 
662 	nfc_genl_target_lost(dev, target_idx);
663 
664 	return 0;
665 }
666 EXPORT_SYMBOL(nfc_target_lost);
667 
668 inline void nfc_driver_failure(struct nfc_dev *dev, int err)
669 {
670 	nfc_targets_found(dev, NULL, 0);
671 }
672 EXPORT_SYMBOL(nfc_driver_failure);
673 
674 static void nfc_release(struct device *d)
675 {
676 	struct nfc_dev *dev = to_nfc_dev(d);
677 
678 	pr_debug("dev_name=%s\n", dev_name(&dev->dev));
679 
680 	if (dev->ops->check_presence) {
681 		del_timer_sync(&dev->check_pres_timer);
682 		destroy_workqueue(dev->check_pres_wq);
683 	}
684 
685 	nfc_genl_data_exit(&dev->genl_data);
686 	kfree(dev->targets);
687 	kfree(dev);
688 }
689 
690 static void nfc_check_pres_work(struct work_struct *work)
691 {
692 	struct nfc_dev *dev = container_of(work, struct nfc_dev,
693 					   check_pres_work);
694 	int rc;
695 
696 	device_lock(&dev->dev);
697 
698 	if (dev->active_target && timer_pending(&dev->check_pres_timer) == 0) {
699 		rc = dev->ops->check_presence(dev, dev->active_target);
700 		if (!rc) {
701 			mod_timer(&dev->check_pres_timer, jiffies +
702 				  msecs_to_jiffies(NFC_CHECK_PRES_FREQ_MS));
703 		} else {
704 			u32 active_target_idx = dev->active_target->idx;
705 			device_unlock(&dev->dev);
706 			nfc_target_lost(dev, active_target_idx);
707 			return;
708 		}
709 	}
710 
711 	device_unlock(&dev->dev);
712 }
713 
714 static void nfc_check_pres_timeout(unsigned long data)
715 {
716 	struct nfc_dev *dev = (struct nfc_dev *)data;
717 
718 	queue_work(dev->check_pres_wq, &dev->check_pres_work);
719 }
720 
721 struct class nfc_class = {
722 	.name = "nfc",
723 	.dev_release = nfc_release,
724 };
725 EXPORT_SYMBOL(nfc_class);
726 
727 static int match_idx(struct device *d, void *data)
728 {
729 	struct nfc_dev *dev = to_nfc_dev(d);
730 	unsigned int *idx = data;
731 
732 	return dev->idx == *idx;
733 }
734 
735 struct nfc_dev *nfc_get_device(unsigned int idx)
736 {
737 	struct device *d;
738 
739 	d = class_find_device(&nfc_class, NULL, &idx, match_idx);
740 	if (!d)
741 		return NULL;
742 
743 	return to_nfc_dev(d);
744 }
745 
746 /**
747  * nfc_allocate_device - allocate a new nfc device
748  *
749  * @ops: device operations
750  * @supported_protocols: NFC protocols supported by the device
751  */
752 struct nfc_dev *nfc_allocate_device(struct nfc_ops *ops,
753 				    u32 supported_protocols,
754 				    int tx_headroom, int tx_tailroom)
755 {
756 	static atomic_t dev_no = ATOMIC_INIT(0);
757 	struct nfc_dev *dev;
758 
759 	if (!ops->start_poll || !ops->stop_poll || !ops->activate_target ||
760 	    !ops->deactivate_target || !ops->im_transceive)
761 		return NULL;
762 
763 	if (!supported_protocols)
764 		return NULL;
765 
766 	dev = kzalloc(sizeof(struct nfc_dev), GFP_KERNEL);
767 	if (!dev)
768 		return NULL;
769 
770 	dev->dev.class = &nfc_class;
771 	dev->idx = atomic_inc_return(&dev_no) - 1;
772 	dev_set_name(&dev->dev, "nfc%d", dev->idx);
773 	device_initialize(&dev->dev);
774 
775 	dev->ops = ops;
776 	dev->supported_protocols = supported_protocols;
777 	dev->tx_headroom = tx_headroom;
778 	dev->tx_tailroom = tx_tailroom;
779 
780 	nfc_genl_data_init(&dev->genl_data);
781 
782 
783 	/* first generation must not be 0 */
784 	dev->targets_generation = 1;
785 
786 	if (ops->check_presence) {
787 		char name[32];
788 		init_timer(&dev->check_pres_timer);
789 		dev->check_pres_timer.data = (unsigned long)dev;
790 		dev->check_pres_timer.function = nfc_check_pres_timeout;
791 
792 		INIT_WORK(&dev->check_pres_work, nfc_check_pres_work);
793 		snprintf(name, sizeof(name), "nfc%d_check_pres_wq", dev->idx);
794 		dev->check_pres_wq = alloc_workqueue(name, WQ_NON_REENTRANT |
795 						     WQ_UNBOUND |
796 						     WQ_MEM_RECLAIM, 1);
797 		if (dev->check_pres_wq == NULL) {
798 			kfree(dev);
799 			return NULL;
800 		}
801 	}
802 
803 	return dev;
804 }
805 EXPORT_SYMBOL(nfc_allocate_device);
806 
807 /**
808  * nfc_register_device - register a nfc device in the nfc subsystem
809  *
810  * @dev: The nfc device to register
811  */
812 int nfc_register_device(struct nfc_dev *dev)
813 {
814 	int rc;
815 
816 	pr_debug("dev_name=%s\n", dev_name(&dev->dev));
817 
818 	mutex_lock(&nfc_devlist_mutex);
819 	nfc_devlist_generation++;
820 	rc = device_add(&dev->dev);
821 	mutex_unlock(&nfc_devlist_mutex);
822 
823 	if (rc < 0)
824 		return rc;
825 
826 	rc = nfc_llcp_register_device(dev);
827 	if (rc)
828 		pr_err("Could not register llcp device\n");
829 
830 	rc = nfc_genl_device_added(dev);
831 	if (rc)
832 		pr_debug("The userspace won't be notified that the device %s was added\n",
833 			 dev_name(&dev->dev));
834 
835 	return 0;
836 }
837 EXPORT_SYMBOL(nfc_register_device);
838 
839 /**
840  * nfc_unregister_device - unregister a nfc device in the nfc subsystem
841  *
842  * @dev: The nfc device to unregister
843  */
844 void nfc_unregister_device(struct nfc_dev *dev)
845 {
846 	int rc;
847 
848 	pr_debug("dev_name=%s\n", dev_name(&dev->dev));
849 
850 	mutex_lock(&nfc_devlist_mutex);
851 	nfc_devlist_generation++;
852 
853 	/* lock to avoid unregistering a device while an operation
854 	   is in progress */
855 	device_lock(&dev->dev);
856 	device_del(&dev->dev);
857 	device_unlock(&dev->dev);
858 
859 	mutex_unlock(&nfc_devlist_mutex);
860 
861 	nfc_llcp_unregister_device(dev);
862 
863 	rc = nfc_genl_device_removed(dev);
864 	if (rc)
865 		pr_debug("The userspace won't be notified that the device %s was removed\n",
866 			 dev_name(&dev->dev));
867 
868 }
869 EXPORT_SYMBOL(nfc_unregister_device);
870 
871 static int __init nfc_init(void)
872 {
873 	int rc;
874 
875 	pr_info("NFC Core ver %s\n", VERSION);
876 
877 	rc = class_register(&nfc_class);
878 	if (rc)
879 		return rc;
880 
881 	rc = nfc_genl_init();
882 	if (rc)
883 		goto err_genl;
884 
885 	/* the first generation must not be 0 */
886 	nfc_devlist_generation = 1;
887 
888 	rc = rawsock_init();
889 	if (rc)
890 		goto err_rawsock;
891 
892 	rc = nfc_llcp_init();
893 	if (rc)
894 		goto err_llcp_sock;
895 
896 	rc = af_nfc_init();
897 	if (rc)
898 		goto err_af_nfc;
899 
900 	return 0;
901 
902 err_af_nfc:
903 	nfc_llcp_exit();
904 err_llcp_sock:
905 	rawsock_exit();
906 err_rawsock:
907 	nfc_genl_exit();
908 err_genl:
909 	class_unregister(&nfc_class);
910 	return rc;
911 }
912 
913 static void __exit nfc_exit(void)
914 {
915 	af_nfc_exit();
916 	nfc_llcp_exit();
917 	rawsock_exit();
918 	nfc_genl_exit();
919 	class_unregister(&nfc_class);
920 }
921 
922 subsys_initcall(nfc_init);
923 module_exit(nfc_exit);
924 
925 MODULE_AUTHOR("Lauro Ramos Venancio <lauro.venancio@openbossa.org>");
926 MODULE_DESCRIPTION("NFC Core ver " VERSION);
927 MODULE_VERSION(VERSION);
928 MODULE_LICENSE("GPL");
929 MODULE_ALIAS_NETPROTO(PF_NFC);
930 MODULE_ALIAS_GENL_FAMILY(NFC_GENL_NAME);
931