xref: /linux/drivers/nfc/st21nfca/i2c.c (revision 9e9f60108423f18a99c9cc93ef7f23490ecc709b)
1 /*
2  * I2C Link Layer for ST21NFCA HCI based Driver
3  * Copyright (C) 2014  STMicroelectronics SAS. All rights reserved.
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms and conditions of the GNU General Public License,
7  * version 2, as published by the Free Software Foundation.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, see <http://www.gnu.org/licenses/>.
16  */
17 
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 
20 #include <linux/crc-ccitt.h>
21 #include <linux/module.h>
22 #include <linux/i2c.h>
23 #include <linux/gpio.h>
24 #include <linux/of_irq.h>
25 #include <linux/of_gpio.h>
26 #include <linux/miscdevice.h>
27 #include <linux/interrupt.h>
28 #include <linux/delay.h>
29 #include <linux/nfc.h>
30 #include <linux/firmware.h>
31 #include <linux/platform_data/st21nfca.h>
32 #include <asm/unaligned.h>
33 
34 #include <net/nfc/hci.h>
35 #include <net/nfc/llc.h>
36 #include <net/nfc/nfc.h>
37 
38 #include "st21nfca.h"
39 
40 /*
41  * Every frame starts with ST21NFCA_SOF_EOF and ends with ST21NFCA_SOF_EOF.
42  * Because ST21NFCA_SOF_EOF is a possible data value, there is a mecanism
43  * called byte stuffing has been introduced.
44  *
45  * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING
46  * - insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)
47  * - xor byte with ST21NFCA_BYTE_STUFFING_MASK
48  */
49 #define ST21NFCA_SOF_EOF		0x7e
50 #define ST21NFCA_BYTE_STUFFING_MASK	0x20
51 #define ST21NFCA_ESCAPE_BYTE_STUFFING	0x7d
52 
53 /* SOF + 00 */
54 #define ST21NFCA_FRAME_HEADROOM			2
55 
56 /* 2 bytes crc + EOF */
57 #define ST21NFCA_FRAME_TAILROOM 3
58 #define IS_START_OF_FRAME(buf) (buf[0] == ST21NFCA_SOF_EOF && \
59 				buf[1] == 0)
60 
61 #define ST21NFCA_HCI_I2C_DRIVER_NAME "st21nfca_hci_i2c"
62 
63 static struct i2c_device_id st21nfca_hci_i2c_id_table[] = {
64 	{ST21NFCA_HCI_DRIVER_NAME, 0},
65 	{}
66 };
67 
68 MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table);
69 
70 struct st21nfca_i2c_phy {
71 	struct i2c_client *i2c_dev;
72 	struct nfc_hci_dev *hdev;
73 
74 	unsigned int gpio_ena;
75 	unsigned int irq_polarity;
76 
77 	struct sk_buff *pending_skb;
78 	int current_read_len;
79 	/*
80 	 * crc might have fail because i2c macro
81 	 * is disable due to other interface activity
82 	 */
83 	int crc_trials;
84 
85 	int powered;
86 	int run_mode;
87 
88 	/*
89 	 * < 0 if hardware error occured (e.g. i2c err)
90 	 * and prevents normal operation.
91 	 */
92 	int hard_fault;
93 	struct mutex phy_lock;
94 };
95 static u8 len_seq[] = { 16, 24, 12, 29 };
96 static u16 wait_tab[] = { 2, 3, 5, 15, 20, 40};
97 
98 #define I2C_DUMP_SKB(info, skb)					\
99 do {								\
100 	pr_debug("%s:\n", info);				\
101 	print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET,	\
102 		       16, 1, (skb)->data, (skb)->len, 0);	\
103 } while (0)
104 
105 /*
106  * In order to get the CLF in a known state we generate an internal reboot
107  * using a proprietary command.
108  * Once the reboot is completed, we expect to receive a ST21NFCA_SOF_EOF
109  * fill buffer.
110  */
111 static int st21nfca_hci_platform_init(struct st21nfca_i2c_phy *phy)
112 {
113 	u16 wait_reboot[] = { 50, 300, 1000 };
114 	char reboot_cmd[] = { 0x7E, 0x66, 0x48, 0xF6, 0x7E };
115 	u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE];
116 	int i, r = -1;
117 
118 	for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
119 		r = i2c_master_send(phy->i2c_dev, reboot_cmd,
120 				    sizeof(reboot_cmd));
121 		if (r < 0)
122 			msleep(wait_reboot[i]);
123 	}
124 	if (r < 0)
125 		return r;
126 
127 	/* CLF is spending about 20ms to do an internal reboot */
128 	msleep(20);
129 	r = -1;
130 	for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
131 		r = i2c_master_recv(phy->i2c_dev, tmp,
132 				    ST21NFCA_HCI_LLC_MAX_SIZE);
133 		if (r < 0)
134 			msleep(wait_reboot[i]);
135 	}
136 	if (r < 0)
137 		return r;
138 
139 	for (i = 0; i < ST21NFCA_HCI_LLC_MAX_SIZE &&
140 		tmp[i] == ST21NFCA_SOF_EOF; i++)
141 		;
142 
143 	if (r != ST21NFCA_HCI_LLC_MAX_SIZE)
144 		return -ENODEV;
145 
146 	usleep_range(1000, 1500);
147 	return 0;
148 }
149 
150 static int st21nfca_hci_i2c_enable(void *phy_id)
151 {
152 	struct st21nfca_i2c_phy *phy = phy_id;
153 
154 	gpio_set_value(phy->gpio_ena, 1);
155 	phy->powered = 1;
156 	phy->run_mode = ST21NFCA_HCI_MODE;
157 
158 	usleep_range(10000, 15000);
159 
160 	return 0;
161 }
162 
163 static void st21nfca_hci_i2c_disable(void *phy_id)
164 {
165 	struct st21nfca_i2c_phy *phy = phy_id;
166 
167 	pr_info("\n");
168 	gpio_set_value(phy->gpio_ena, 0);
169 
170 	phy->powered = 0;
171 }
172 
173 static void st21nfca_hci_add_len_crc(struct sk_buff *skb)
174 {
175 	u16 crc;
176 	u8 tmp;
177 
178 	*skb_push(skb, 1) = 0;
179 
180 	crc = crc_ccitt(0xffff, skb->data, skb->len);
181 	crc = ~crc;
182 
183 	tmp = crc & 0x00ff;
184 	*skb_put(skb, 1) = tmp;
185 
186 	tmp = (crc >> 8) & 0x00ff;
187 	*skb_put(skb, 1) = tmp;
188 }
189 
190 static void st21nfca_hci_remove_len_crc(struct sk_buff *skb)
191 {
192 	skb_pull(skb, ST21NFCA_FRAME_HEADROOM);
193 	skb_trim(skb, skb->len - ST21NFCA_FRAME_TAILROOM);
194 }
195 
196 /*
197  * Writing a frame must not return the number of written bytes.
198  * It must return either zero for success, or <0 for error.
199  * In addition, it must not alter the skb
200  */
201 static int st21nfca_hci_i2c_write(void *phy_id, struct sk_buff *skb)
202 {
203 	int r = -1, i, j;
204 	struct st21nfca_i2c_phy *phy = phy_id;
205 	struct i2c_client *client = phy->i2c_dev;
206 	u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE * 2];
207 
208 	I2C_DUMP_SKB("st21nfca_hci_i2c_write", skb);
209 
210 
211 	if (phy->hard_fault != 0)
212 		return phy->hard_fault;
213 
214 	/*
215 	 * Compute CRC before byte stuffing computation on frame
216 	 * Note st21nfca_hci_add_len_crc is doing a byte stuffing
217 	 * on its own value
218 	 */
219 	st21nfca_hci_add_len_crc(skb);
220 
221 	/* add ST21NFCA_SOF_EOF on tail */
222 	*skb_put(skb, 1) = ST21NFCA_SOF_EOF;
223 	/* add ST21NFCA_SOF_EOF on head */
224 	*skb_push(skb, 1) = ST21NFCA_SOF_EOF;
225 
226 	/*
227 	 * Compute byte stuffing
228 	 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING
229 	 * insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)
230 	 * xor byte with ST21NFCA_BYTE_STUFFING_MASK
231 	 */
232 	tmp[0] = skb->data[0];
233 	for (i = 1, j = 1; i < skb->len - 1; i++, j++) {
234 		if (skb->data[i] == ST21NFCA_SOF_EOF
235 		    || skb->data[i] == ST21NFCA_ESCAPE_BYTE_STUFFING) {
236 			tmp[j] = ST21NFCA_ESCAPE_BYTE_STUFFING;
237 			j++;
238 			tmp[j] = skb->data[i] ^ ST21NFCA_BYTE_STUFFING_MASK;
239 		} else {
240 			tmp[j] = skb->data[i];
241 		}
242 	}
243 	tmp[j] = skb->data[i];
244 	j++;
245 
246 	/*
247 	 * Manage sleep mode
248 	 * Try 3 times to send data with delay between each
249 	 */
250 	mutex_lock(&phy->phy_lock);
251 	for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++) {
252 		r = i2c_master_send(client, tmp, j);
253 		if (r < 0)
254 			msleep(wait_tab[i]);
255 	}
256 	mutex_unlock(&phy->phy_lock);
257 
258 	if (r >= 0) {
259 		if (r != j)
260 			r = -EREMOTEIO;
261 		else
262 			r = 0;
263 	}
264 
265 	st21nfca_hci_remove_len_crc(skb);
266 
267 	return r;
268 }
269 
270 static int get_frame_size(u8 *buf, int buflen)
271 {
272 	int len = 0;
273 
274 	if (buf[len + 1] == ST21NFCA_SOF_EOF)
275 		return 0;
276 
277 	for (len = 1; len < buflen && buf[len] != ST21NFCA_SOF_EOF; len++)
278 		;
279 
280 	return len;
281 }
282 
283 static int check_crc(u8 *buf, int buflen)
284 {
285 	u16 crc;
286 
287 	crc = crc_ccitt(0xffff, buf, buflen - 2);
288 	crc = ~crc;
289 
290 	if (buf[buflen - 2] != (crc & 0xff) || buf[buflen - 1] != (crc >> 8)) {
291 		pr_err(ST21NFCA_HCI_DRIVER_NAME
292 		       ": CRC error 0x%x != 0x%x 0x%x\n", crc, buf[buflen - 1],
293 		       buf[buflen - 2]);
294 
295 		pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
296 		print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
297 			       16, 2, buf, buflen, false);
298 		return -EPERM;
299 	}
300 	return 0;
301 }
302 
303 /*
304  * Prepare received data for upper layer.
305  * Received data include byte stuffing, crc and sof/eof
306  * which is not usable by hci part.
307  * returns:
308  * frame size without sof/eof, header and byte stuffing
309  * -EBADMSG : frame was incorrect and discarded
310  */
311 static int st21nfca_hci_i2c_repack(struct sk_buff *skb)
312 {
313 	int i, j, r, size;
314 
315 	if (skb->len < 1 || (skb->len > 1 && skb->data[1] != 0))
316 		return -EBADMSG;
317 
318 	size = get_frame_size(skb->data, skb->len);
319 	if (size > 0) {
320 		skb_trim(skb, size);
321 		/* remove ST21NFCA byte stuffing for upper layer */
322 		for (i = 1, j = 0; i < skb->len; i++) {
323 			if (skb->data[i + j] ==
324 					(u8) ST21NFCA_ESCAPE_BYTE_STUFFING) {
325 				skb->data[i] = skb->data[i + j + 1]
326 						| ST21NFCA_BYTE_STUFFING_MASK;
327 				i++;
328 				j++;
329 			}
330 			skb->data[i] = skb->data[i + j];
331 		}
332 		/* remove byte stuffing useless byte */
333 		skb_trim(skb, i - j);
334 		/* remove ST21NFCA_SOF_EOF from head */
335 		skb_pull(skb, 1);
336 
337 		r = check_crc(skb->data, skb->len);
338 		if (r != 0) {
339 			i = 0;
340 			return -EBADMSG;
341 		}
342 
343 		/* remove headbyte */
344 		skb_pull(skb, 1);
345 		/* remove crc. Byte Stuffing is already removed here */
346 		skb_trim(skb, skb->len - 2);
347 		return skb->len;
348 	}
349 	return 0;
350 }
351 
352 /*
353  * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees
354  * that i2c bus will be flushed and that next read will start on a new frame.
355  * returned skb contains only LLC header and payload.
356  * returns:
357  * frame size : if received frame is complete (find ST21NFCA_SOF_EOF at
358  * end of read)
359  * -EAGAIN : if received frame is incomplete (not find ST21NFCA_SOF_EOF
360  * at end of read)
361  * -EREMOTEIO : i2c read error (fatal)
362  * -EBADMSG : frame was incorrect and discarded
363  * (value returned from st21nfca_hci_i2c_repack)
364  * -EIO : if no ST21NFCA_SOF_EOF is found after reaching
365  * the read length end sequence
366  */
367 static int st21nfca_hci_i2c_read(struct st21nfca_i2c_phy *phy,
368 				 struct sk_buff *skb)
369 {
370 	int r, i;
371 	u8 len;
372 	u8 buf[ST21NFCA_HCI_LLC_MAX_PAYLOAD];
373 	struct i2c_client *client = phy->i2c_dev;
374 
375 	if (phy->current_read_len < ARRAY_SIZE(len_seq)) {
376 		len = len_seq[phy->current_read_len];
377 
378 		/*
379 		 * Add retry mecanism
380 		 * Operation on I2C interface may fail in case of operation on
381 		 * RF or SWP interface
382 		 */
383 		r = 0;
384 		mutex_lock(&phy->phy_lock);
385 		for (i = 0; i < ARRAY_SIZE(wait_tab) && r <= 0; i++) {
386 			r = i2c_master_recv(client, buf, len);
387 			if (r < 0)
388 				msleep(wait_tab[i]);
389 		}
390 		mutex_unlock(&phy->phy_lock);
391 
392 		if (r != len) {
393 			phy->current_read_len = 0;
394 			return -EREMOTEIO;
395 		}
396 
397 		/*
398 		 * The first read sequence does not start with SOF.
399 		 * Data is corrupeted so we drop it.
400 		 */
401 		if (!phy->current_read_len && !IS_START_OF_FRAME(buf)) {
402 			skb_trim(skb, 0);
403 			phy->current_read_len = 0;
404 			return -EIO;
405 		} else if (phy->current_read_len && IS_START_OF_FRAME(buf)) {
406 			/*
407 			 * Previous frame transmission was interrupted and
408 			 * the frame got repeated.
409 			 * Received frame start with ST21NFCA_SOF_EOF + 00.
410 			 */
411 			skb_trim(skb, 0);
412 			phy->current_read_len = 0;
413 		}
414 
415 		memcpy(skb_put(skb, len), buf, len);
416 
417 		if (skb->data[skb->len - 1] == ST21NFCA_SOF_EOF) {
418 			phy->current_read_len = 0;
419 			return st21nfca_hci_i2c_repack(skb);
420 		}
421 		phy->current_read_len++;
422 		return -EAGAIN;
423 	}
424 	return -EIO;
425 }
426 
427 /*
428  * Reads an shdlc frame from the chip. This is not as straightforward as it
429  * seems. The frame format is data-crc, and corruption can occur anywhere
430  * while transiting on i2c bus, such that we could read an invalid data.
431  * The tricky case is when we read a corrupted data or crc. We must detect
432  * this here in order to determine that data can be transmitted to the hci
433  * core. This is the reason why we check the crc here.
434  * The CLF will repeat a frame until we send a RR on that frame.
435  *
436  * On ST21NFCA, IRQ goes in idle when read starts. As no size information are
437  * available in the incoming data, other IRQ might come. Every IRQ will trigger
438  * a read sequence with different length and will fill the current frame.
439  * The reception is complete once we reach a ST21NFCA_SOF_EOF.
440  */
441 static irqreturn_t st21nfca_hci_irq_thread_fn(int irq, void *phy_id)
442 {
443 	struct st21nfca_i2c_phy *phy = phy_id;
444 	struct i2c_client *client;
445 
446 	int r;
447 
448 	if (!phy || irq != phy->i2c_dev->irq) {
449 		WARN_ON_ONCE(1);
450 		return IRQ_NONE;
451 	}
452 
453 	client = phy->i2c_dev;
454 	dev_dbg(&client->dev, "IRQ\n");
455 
456 	if (phy->hard_fault != 0)
457 		return IRQ_HANDLED;
458 
459 	r = st21nfca_hci_i2c_read(phy, phy->pending_skb);
460 	if (r == -EREMOTEIO) {
461 		phy->hard_fault = r;
462 
463 		nfc_hci_recv_frame(phy->hdev, NULL);
464 
465 		return IRQ_HANDLED;
466 	} else if (r == -EAGAIN || r == -EIO) {
467 		return IRQ_HANDLED;
468 	} else if (r == -EBADMSG && phy->crc_trials < ARRAY_SIZE(wait_tab)) {
469 		/*
470 		 * With ST21NFCA, only one interface (I2C, RF or SWP)
471 		 * may be active at a time.
472 		 * Having incorrect crc is usually due to i2c macrocell
473 		 * deactivation in the middle of a transmission.
474 		 * It may generate corrupted data on i2c.
475 		 * We give sometime to get i2c back.
476 		 * The complete frame will be repeated.
477 		 */
478 		msleep(wait_tab[phy->crc_trials]);
479 		phy->crc_trials++;
480 		phy->current_read_len = 0;
481 		kfree_skb(phy->pending_skb);
482 	} else if (r > 0) {
483 		/*
484 		 * We succeeded to read data from the CLF and
485 		 * data is valid.
486 		 * Reset counter.
487 		 */
488 		nfc_hci_recv_frame(phy->hdev, phy->pending_skb);
489 		phy->crc_trials = 0;
490 	} else {
491 		kfree_skb(phy->pending_skb);
492 	}
493 
494 	phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
495 	if (phy->pending_skb == NULL) {
496 		phy->hard_fault = -ENOMEM;
497 		nfc_hci_recv_frame(phy->hdev, NULL);
498 	}
499 
500 	return IRQ_HANDLED;
501 }
502 
503 static struct nfc_phy_ops i2c_phy_ops = {
504 	.write = st21nfca_hci_i2c_write,
505 	.enable = st21nfca_hci_i2c_enable,
506 	.disable = st21nfca_hci_i2c_disable,
507 };
508 
509 #ifdef CONFIG_OF
510 static int st21nfca_hci_i2c_of_request_resources(struct i2c_client *client)
511 {
512 	struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);
513 	struct device_node *pp;
514 	int gpio;
515 	int r;
516 
517 	pp = client->dev.of_node;
518 	if (!pp)
519 		return -ENODEV;
520 
521 	/* Get GPIO from device tree */
522 	gpio = of_get_named_gpio(pp, "enable-gpios", 0);
523 	if (gpio < 0) {
524 		nfc_err(&client->dev, "Failed to retrieve enable-gpios from device tree\n");
525 		return gpio;
526 	}
527 
528 	/* GPIO request and configuration */
529 	r = devm_gpio_request_one(&client->dev, gpio, GPIOF_OUT_INIT_HIGH,
530 				  "clf_enable");
531 	if (r) {
532 		nfc_err(&client->dev, "Failed to request enable pin\n");
533 		return r;
534 	}
535 
536 	phy->gpio_ena = gpio;
537 
538 	phy->irq_polarity = irq_get_trigger_type(client->irq);
539 
540 	return 0;
541 }
542 #else
543 static int st21nfca_hci_i2c_of_request_resources(struct i2c_client *client)
544 {
545 	return -ENODEV;
546 }
547 #endif
548 
549 static int st21nfca_hci_i2c_request_resources(struct i2c_client *client)
550 {
551 	struct st21nfca_nfc_platform_data *pdata;
552 	struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);
553 	int r;
554 
555 	pdata = client->dev.platform_data;
556 	if (pdata == NULL) {
557 		nfc_err(&client->dev, "No platform data\n");
558 		return -EINVAL;
559 	}
560 
561 	/* store for later use */
562 	phy->gpio_ena = pdata->gpio_ena;
563 	phy->irq_polarity = pdata->irq_polarity;
564 
565 	if (phy->gpio_ena > 0) {
566 		r = devm_gpio_request_one(&client->dev, phy->gpio_ena,
567 					  GPIOF_OUT_INIT_HIGH, "clf_enable");
568 		if (r) {
569 			pr_err("%s : ena gpio_request failed\n", __FILE__);
570 			return r;
571 		}
572 	}
573 
574 	return 0;
575 }
576 
577 static int st21nfca_hci_i2c_probe(struct i2c_client *client,
578 				  const struct i2c_device_id *id)
579 {
580 	struct st21nfca_i2c_phy *phy;
581 	struct st21nfca_nfc_platform_data *pdata;
582 	int r;
583 
584 	dev_dbg(&client->dev, "%s\n", __func__);
585 	dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
586 
587 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
588 		nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
589 		return -ENODEV;
590 	}
591 
592 	phy = devm_kzalloc(&client->dev, sizeof(struct st21nfca_i2c_phy),
593 			   GFP_KERNEL);
594 	if (!phy) {
595 		nfc_err(&client->dev,
596 			"Cannot allocate memory for st21nfca i2c phy.\n");
597 		return -ENOMEM;
598 	}
599 
600 	phy->i2c_dev = client;
601 	phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
602 	if (phy->pending_skb == NULL)
603 		return -ENOMEM;
604 
605 	phy->current_read_len = 0;
606 	phy->crc_trials = 0;
607 	mutex_init(&phy->phy_lock);
608 	i2c_set_clientdata(client, phy);
609 
610 	pdata = client->dev.platform_data;
611 	if (!pdata && client->dev.of_node) {
612 		r = st21nfca_hci_i2c_of_request_resources(client);
613 		if (r) {
614 			nfc_err(&client->dev, "No platform data\n");
615 			return r;
616 		}
617 	} else if (pdata) {
618 		r = st21nfca_hci_i2c_request_resources(client);
619 		if (r) {
620 			nfc_err(&client->dev, "Cannot get platform resources\n");
621 			return r;
622 		}
623 	} else {
624 		nfc_err(&client->dev, "st21nfca platform resources not available\n");
625 		return -ENODEV;
626 	}
627 
628 	r = st21nfca_hci_platform_init(phy);
629 	if (r < 0) {
630 		nfc_err(&client->dev, "Unable to reboot st21nfca\n");
631 		return r;
632 	}
633 
634 	r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
635 				st21nfca_hci_irq_thread_fn,
636 				phy->irq_polarity | IRQF_ONESHOT,
637 				ST21NFCA_HCI_DRIVER_NAME, phy);
638 	if (r < 0) {
639 		nfc_err(&client->dev, "Unable to register IRQ handler\n");
640 		return r;
641 	}
642 
643 	return st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
644 			       ST21NFCA_FRAME_HEADROOM, ST21NFCA_FRAME_TAILROOM,
645 			       ST21NFCA_HCI_LLC_MAX_PAYLOAD, &phy->hdev);
646 }
647 
648 static int st21nfca_hci_i2c_remove(struct i2c_client *client)
649 {
650 	struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);
651 
652 	dev_dbg(&client->dev, "%s\n", __func__);
653 
654 	st21nfca_hci_remove(phy->hdev);
655 
656 	if (phy->powered)
657 		st21nfca_hci_i2c_disable(phy);
658 
659 	return 0;
660 }
661 
662 #ifdef CONFIG_OF
663 static const struct of_device_id of_st21nfca_i2c_match[] = {
664 	{ .compatible = "st,st21nfca_i2c", },
665 	{}
666 };
667 MODULE_DEVICE_TABLE(of, of_st21nfca_i2c_match);
668 #endif
669 
670 static struct i2c_driver st21nfca_hci_i2c_driver = {
671 	.driver = {
672 		.owner = THIS_MODULE,
673 		.name = ST21NFCA_HCI_I2C_DRIVER_NAME,
674 		.of_match_table = of_match_ptr(of_st21nfca_i2c_match),
675 	},
676 	.probe = st21nfca_hci_i2c_probe,
677 	.id_table = st21nfca_hci_i2c_id_table,
678 	.remove = st21nfca_hci_i2c_remove,
679 };
680 
681 module_i2c_driver(st21nfca_hci_i2c_driver);
682 
683 MODULE_LICENSE("GPL");
684 MODULE_DESCRIPTION(DRIVER_DESC);
685