summaryrefslogtreecommitdiff
path: root/drivers/nfc/st21nfca/i2c.c
blob: 76b55986bcf85b1afd9822ce7be0593a6dd1dc99 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
// SPDX-License-Identifier: GPL-2.0-only
/*
 * I2C Link Layer for ST21NFCA HCI based Driver
 * Copyright (C) 2014  STMicroelectronics SAS. All rights reserved.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/crc-ccitt.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/gpio/consumer.h>
#include <linux/of_irq.h>
#include <linux/of_gpio.h>
#include <linux/acpi.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/nfc.h>
#include <linux/firmware.h>

#include <net/nfc/hci.h>
#include <net/nfc/llc.h>
#include <net/nfc/nfc.h>

#include "st21nfca.h"

/*
 * Every frame starts with ST21NFCA_SOF_EOF and ends with ST21NFCA_SOF_EOF.
 * Because ST21NFCA_SOF_EOF is a possible data value, there is a mecanism
 * called byte stuffing has been introduced.
 *
 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING
 * - insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)
 * - xor byte with ST21NFCA_BYTE_STUFFING_MASK
 */
#define ST21NFCA_SOF_EOF		0x7e
#define ST21NFCA_BYTE_STUFFING_MASK	0x20
#define ST21NFCA_ESCAPE_BYTE_STUFFING	0x7d

/* SOF + 00 */
#define ST21NFCA_FRAME_HEADROOM			2

/* 2 bytes crc + EOF */
#define ST21NFCA_FRAME_TAILROOM 3
#define IS_START_OF_FRAME(buf) (buf[0] == ST21NFCA_SOF_EOF && \
				buf[1] == 0)

#define ST21NFCA_HCI_DRIVER_NAME "st21nfca_hci"
#define ST21NFCA_HCI_I2C_DRIVER_NAME "st21nfca_hci_i2c"

struct st21nfca_i2c_phy {
	struct i2c_client *i2c_dev;
	struct nfc_hci_dev *hdev;

	struct gpio_desc *gpiod_ena;
	struct st21nfca_se_status se_status;

	struct sk_buff *pending_skb;
	int current_read_len;
	/*
	 * crc might have fail because i2c macro
	 * is disable due to other interface activity
	 */
	int crc_trials;

	int powered;
	int run_mode;

	/*
	 * < 0 if hardware error occured (e.g. i2c err)
	 * and prevents normal operation.
	 */
	int hard_fault;
	struct mutex phy_lock;
};

static const u8 len_seq[] = { 16, 24, 12, 29 };
static const u16 wait_tab[] = { 2, 3, 5, 15, 20, 40};

#define I2C_DUMP_SKB(info, skb)					\
do {								\
	pr_debug("%s:\n", info);				\
	print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET,	\
		       16, 1, (skb)->data, (skb)->len, 0);	\
} while (0)

/*
 * In order to get the CLF in a known state we generate an internal reboot
 * using a proprietary command.
 * Once the reboot is completed, we expect to receive a ST21NFCA_SOF_EOF
 * fill buffer.
 */
static int st21nfca_hci_platform_init(struct st21nfca_i2c_phy *phy)
{
	u16 wait_reboot[] = { 50, 300, 1000 };
	char reboot_cmd[] = { 0x7E, 0x66, 0x48, 0xF6, 0x7E };
	u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE];
	int i, r = -1;

	for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
		r = i2c_master_send(phy->i2c_dev, reboot_cmd,
				    sizeof(reboot_cmd));
		if (r < 0)
			msleep(wait_reboot[i]);
	}
	if (r < 0)
		return r;

	/* CLF is spending about 20ms to do an internal reboot */
	msleep(20);
	r = -1;
	for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
		r = i2c_master_recv(phy->i2c_dev, tmp,
				    ST21NFCA_HCI_LLC_MAX_SIZE);
		if (r < 0)
			msleep(wait_reboot[i]);
	}
	if (r < 0)
		return r;

	for (i = 0; i < ST21NFCA_HCI_LLC_MAX_SIZE &&
		tmp[i] == ST21NFCA_SOF_EOF; i++)
		;

	if (r != ST21NFCA_HCI_LLC_MAX_SIZE)
		return -ENODEV;

	usleep_range(1000, 1500);
	return 0;
}

static int st21nfca_hci_i2c_enable(void *phy_id)
{
	struct st21nfca_i2c_phy *phy = phy_id;

	gpiod_set_value(phy->gpiod_ena, 1);
	phy->powered = 1;
	phy->run_mode = ST21NFCA_HCI_MODE;

	usleep_range(10000, 15000);

	return 0;
}

static void st21nfca_hci_i2c_disable(void *phy_id)
{
	struct st21nfca_i2c_phy *phy = phy_id;

	gpiod_set_value(phy->gpiod_ena, 0);

	phy->powered = 0;
}

static void st21nfca_hci_add_len_crc(struct sk_buff *skb)
{
	u16 crc;
	u8 tmp;

	*(u8 *)skb_push(skb, 1) = 0;

	crc = crc_ccitt(0xffff, skb->data, skb->len);
	crc = ~crc;

	tmp = crc & 0x00ff;
	skb_put_u8(skb, tmp);

	tmp = (crc >> 8) & 0x00ff;
	skb_put_u8(skb, tmp);
}

static void st21nfca_hci_remove_len_crc(struct sk_buff *skb)
{
	skb_pull(skb, ST21NFCA_FRAME_HEADROOM);
	skb_trim(skb, skb->len - ST21NFCA_FRAME_TAILROOM);
}

/*
 * Writing a frame must not return the number of written bytes.
 * It must return either zero for success, or <0 for error.
 * In addition, it must not alter the skb
 */
static int st21nfca_hci_i2c_write(void *phy_id, struct sk_buff *skb)
{
	int r = -1, i, j;
	struct st21nfca_i2c_phy *phy = phy_id;
	struct i2c_client *client = phy->i2c_dev;
	u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE * 2];

	I2C_DUMP_SKB("st21nfca_hci_i2c_write", skb);

	if (phy->hard_fault != 0)
		return phy->hard_fault;

	/*
	 * Compute CRC before byte stuffing computation on frame
	 * Note st21nfca_hci_add_len_crc is doing a byte stuffing
	 * on its own value
	 */
	st21nfca_hci_add_len_crc(skb);

	/* add ST21NFCA_SOF_EOF on tail */
	skb_put_u8(skb, ST21NFCA_SOF_EOF);
	/* add ST21NFCA_SOF_EOF on head */
	*(u8 *)skb_push(skb, 1) = ST21NFCA_SOF_EOF;

	/*
	 * Compute byte stuffing
	 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING
	 * insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)
	 * xor byte with ST21NFCA_BYTE_STUFFING_MASK
	 */
	tmp[0] = skb->data[0];
	for (i = 1, j = 1; i < skb->len - 1; i++, j++) {
		if (skb->data[i] == ST21NFCA_SOF_EOF
		    || skb->data[i] == ST21NFCA_ESCAPE_BYTE_STUFFING) {
			tmp[j] = ST21NFCA_ESCAPE_BYTE_STUFFING;
			j++;
			tmp[j] = skb->data[i] ^ ST21NFCA_BYTE_STUFFING_MASK;
		} else {
			tmp[j] = skb->data[i];
		}
	}
	tmp[j] = skb->data[i];
	j++;

	/*
	 * Manage sleep mode
	 * Try 3 times to send data with delay between each
	 */
	mutex_lock(&phy->phy_lock);
	for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++) {
		r = i2c_master_send(client, tmp, j);
		if (r < 0)
			msleep(wait_tab[i]);
	}
	mutex_unlock(&phy->phy_lock);

	if (r >= 0) {
		if (r != j)
			r = -EREMOTEIO;
		else
			r = 0;
	}

	st21nfca_hci_remove_len_crc(skb);

	return r;
}

static int get_frame_size(u8 *buf, int buflen)
{
	int len = 0;

	if (buf[len + 1] == ST21NFCA_SOF_EOF)
		return 0;

	for (len = 1; len < buflen && buf[len] != ST21NFCA_SOF_EOF; len++)
		;

	return len;
}

static int check_crc(u8 *buf, int buflen)
{
	u16 crc;

	crc = crc_ccitt(0xffff, buf, buflen - 2);
	crc = ~crc;

	if (buf[buflen - 2] != (crc & 0xff) || buf[buflen - 1] != (crc >> 8)) {
		pr_err(ST21NFCA_HCI_DRIVER_NAME
		       ": CRC error 0x%x != 0x%x 0x%x\n", crc, buf[buflen - 1],
		       buf[buflen - 2]);

		pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
		print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
			       16, 2, buf, buflen, false);
		return -EPERM;
	}
	return 0;
}

/*
 * Prepare received data for upper layer.
 * Received data include byte stuffing, crc and sof/eof
 * which is not usable by hci part.
 * returns:
 * frame size without sof/eof, header and byte stuffing
 * -EBADMSG : frame was incorrect and discarded
 */
static int st21nfca_hci_i2c_repack(struct sk_buff *skb)
{
	int i, j, r, size;

	if (skb->len < 1 || (skb->len > 1 && skb->data[1] != 0))
		return -EBADMSG;

	size = get_frame_size(skb->data, skb->len);
	if (size > 0) {
		skb_trim(skb, size);
		/* remove ST21NFCA byte stuffing for upper layer */
		for (i = 1, j = 0; i < skb->len; i++) {
			if (skb->data[i + j] ==
					(u8) ST21NFCA_ESCAPE_BYTE_STUFFING) {
				skb->data[i] = skb->data[i + j + 1]
						| ST21NFCA_BYTE_STUFFING_MASK;
				i++;
				j++;
			}
			skb->data[i] = skb->data[i + j];
		}
		/* remove byte stuffing useless byte */
		skb_trim(skb, i - j);
		/* remove ST21NFCA_SOF_EOF from head */
		skb_pull(skb, 1);

		r = check_crc(skb->data, skb->len);
		if (r != 0)
			return -EBADMSG;

		/* remove headbyte */
		skb_pull(skb, 1);
		/* remove crc. Byte Stuffing is already removed here */
		skb_trim(skb, skb->len - 2);
		return skb->len;
	}
	return 0;
}

/*
 * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees
 * that i2c bus will be flushed and that next read will start on a new frame.
 * returned skb contains only LLC header and payload.
 * returns:
 * frame size : if received frame is complete (find ST21NFCA_SOF_EOF at
 * end of read)
 * -EAGAIN : if received frame is incomplete (not find ST21NFCA_SOF_EOF
 * at end of read)
 * -EREMOTEIO : i2c read error (fatal)
 * -EBADMSG : frame was incorrect and discarded
 * (value returned from st21nfca_hci_i2c_repack)
 * -EIO : if no ST21NFCA_SOF_EOF is found after reaching
 * the read length end sequence
 */
static int st21nfca_hci_i2c_read(struct st21nfca_i2c_phy *phy,
				 struct sk_buff *skb)
{
	int r, i;
	u8 len;
	u8 buf[ST21NFCA_HCI_LLC_MAX_PAYLOAD];
	struct i2c_client *client = phy->i2c_dev;

	if (phy->current_read_len < ARRAY_SIZE(len_seq)) {
		len = len_seq[phy->current_read_len];

		/*
		 * Add retry mecanism
		 * Operation on I2C interface may fail in case of operation on
		 * RF or SWP interface
		 */
		r = 0;
		mutex_lock(&phy->phy_lock);
		for (i = 0; i < ARRAY_SIZE(wait_tab) && r <= 0; i++) {
			r = i2c_master_recv(client, buf, len);
			if (r < 0)
				msleep(wait_tab[i]);
		}
		mutex_unlock(&phy->phy_lock);

		if (r != len) {
			phy->current_read_len = 0;
			return -EREMOTEIO;
		}

		/*
		 * The first read sequence does not start with SOF.
		 * Data is corrupeted so we drop it.
		 */
		if (!phy->current_read_len && !IS_START_OF_FRAME(buf)) {
			skb_trim(skb, 0);
			phy->current_read_len = 0;
			return -EIO;
		} else if (phy->current_read_len && IS_START_OF_FRAME(buf)) {
			/*
			 * Previous frame transmission was interrupted and
			 * the frame got repeated.
			 * Received frame start with ST21NFCA_SOF_EOF + 00.
			 */
			skb_trim(skb, 0);
			phy->current_read_len = 0;
		}

		skb_put_data(skb, buf, len);

		if (skb->data[skb->len - 1] == ST21NFCA_SOF_EOF) {
			phy->current_read_len = 0;
			return st21nfca_hci_i2c_repack(skb);
		}
		phy->current_read_len++;
		return -EAGAIN;
	}
	return -EIO;
}

/*
 * Reads an shdlc frame from the chip. This is not as straightforward as it
 * seems. The frame format is data-crc, and corruption can occur anywhere
 * while transiting on i2c bus, such that we could read an invalid data.
 * The tricky case is when we read a corrupted data or crc. We must detect
 * this here in order to determine that data can be transmitted to the hci
 * core. This is the reason why we check the crc here.
 * The CLF will repeat a frame until we send a RR on that frame.
 *
 * On ST21NFCA, IRQ goes in idle when read starts. As no size information are
 * available in the incoming data, other IRQ might come. Every IRQ will trigger
 * a read sequence with different length and will fill the current frame.
 * The reception is complete once we reach a ST21NFCA_SOF_EOF.
 */
static irqreturn_t st21nfca_hci_irq_thread_fn(int irq, void *phy_id)
{
	struct st21nfca_i2c_phy *phy = phy_id;

	int r;

	if (!phy || irq != phy->i2c_dev->irq) {
		WARN_ON_ONCE(1);
		return IRQ_NONE;
	}

	if (phy->hard_fault != 0)
		return IRQ_HANDLED;

	r = st21nfca_hci_i2c_read(phy, phy->pending_skb);
	if (r == -EREMOTEIO) {
		phy->hard_fault = r;

		nfc_hci_recv_frame(phy->hdev, NULL);

		return IRQ_HANDLED;
	} else if (r == -EAGAIN || r == -EIO) {
		return IRQ_HANDLED;
	} else if (r == -EBADMSG && phy->crc_trials < ARRAY_SIZE(wait_tab)) {
		/*
		 * With ST21NFCA, only one interface (I2C, RF or SWP)
		 * may be active at a time.
		 * Having incorrect crc is usually due to i2c macrocell
		 * deactivation in the middle of a transmission.
		 * It may generate corrupted data on i2c.
		 * We give sometime to get i2c back.
		 * The complete frame will be repeated.
		 */
		msleep(wait_tab[phy->crc_trials]);
		phy->crc_trials++;
		phy->current_read_len = 0;
		kfree_skb(phy->pending_skb);
	} else if (r > 0) {
		/*
		 * We succeeded to read data from the CLF and
		 * data is valid.
		 * Reset counter.
		 */
		nfc_hci_recv_frame(phy->hdev, phy->pending_skb);
		phy->crc_trials = 0;
	} else {
		kfree_skb(phy->pending_skb);
	}

	phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
	if (phy->pending_skb == NULL) {
		phy->hard_fault = -ENOMEM;
		nfc_hci_recv_frame(phy->hdev, NULL);
	}

	return IRQ_HANDLED;
}

static const struct nfc_phy_ops i2c_phy_ops = {
	.write = st21nfca_hci_i2c_write,
	.enable = st21nfca_hci_i2c_enable,
	.disable = st21nfca_hci_i2c_disable,
};

static const struct acpi_gpio_params enable_gpios = { 1, 0, false };

static const struct acpi_gpio_mapping acpi_st21nfca_gpios[] = {
	{ "enable-gpios", &enable_gpios, 1 },
	{},
};

static int st21nfca_hci_i2c_probe(struct i2c_client *client,
				  const struct i2c_device_id *id)
{
	struct device *dev = &client->dev;
	struct st21nfca_i2c_phy *phy;
	int r;

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
		nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
		return -ENODEV;
	}

	phy = devm_kzalloc(&client->dev, sizeof(struct st21nfca_i2c_phy),
			   GFP_KERNEL);
	if (!phy)
		return -ENOMEM;

	phy->i2c_dev = client;
	phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
	if (phy->pending_skb == NULL)
		return -ENOMEM;

	phy->current_read_len = 0;
	phy->crc_trials = 0;
	mutex_init(&phy->phy_lock);
	i2c_set_clientdata(client, phy);

	r = devm_acpi_dev_add_driver_gpios(dev, acpi_st21nfca_gpios);
	if (r)
		dev_dbg(dev, "Unable to add GPIO mapping table\n");

	/* Get EN GPIO from resource provider */
	phy->gpiod_ena = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
	if (IS_ERR(phy->gpiod_ena)) {
		nfc_err(dev, "Unable to get ENABLE GPIO\n");
		r = PTR_ERR(phy->gpiod_ena);
		goto out_free;
	}

	phy->se_status.is_ese_present =
			device_property_read_bool(&client->dev, "ese-present");
	phy->se_status.is_uicc_present =
			device_property_read_bool(&client->dev, "uicc-present");

	r = st21nfca_hci_platform_init(phy);
	if (r < 0) {
		nfc_err(&client->dev, "Unable to reboot st21nfca\n");
		goto out_free;
	}

	r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
				st21nfca_hci_irq_thread_fn,
				IRQF_ONESHOT,
				ST21NFCA_HCI_DRIVER_NAME, phy);
	if (r < 0) {
		nfc_err(&client->dev, "Unable to register IRQ handler\n");
		goto out_free;
	}

	r = st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
			       ST21NFCA_FRAME_HEADROOM,
			       ST21NFCA_FRAME_TAILROOM,
			       ST21NFCA_HCI_LLC_MAX_PAYLOAD,
			       &phy->hdev,
			       &phy->se_status);
	if (r)
		goto out_free;

	return 0;

out_free:
	kfree_skb(phy->pending_skb);
	return r;
}

static void st21nfca_hci_i2c_remove(struct i2c_client *client)
{
	struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);

	st21nfca_hci_remove(phy->hdev);

	if (phy->powered)
		st21nfca_hci_i2c_disable(phy);
	kfree_skb(phy->pending_skb);
}

static const struct i2c_device_id st21nfca_hci_i2c_id_table[] = {
	{ST21NFCA_HCI_DRIVER_NAME, 0},
	{}
};
MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table);

static const struct acpi_device_id st21nfca_hci_i2c_acpi_match[] __maybe_unused = {
	{"SMO2100", 0},
	{}
};
MODULE_DEVICE_TABLE(acpi, st21nfca_hci_i2c_acpi_match);

static const struct of_device_id of_st21nfca_i2c_match[] __maybe_unused = {
	{ .compatible = "st,st21nfca-i2c", },
	{ .compatible = "st,st21nfca_i2c", },
	{}
};
MODULE_DEVICE_TABLE(of, of_st21nfca_i2c_match);

static struct i2c_driver st21nfca_hci_i2c_driver = {
	.driver = {
		.name = ST21NFCA_HCI_I2C_DRIVER_NAME,
		.of_match_table = of_match_ptr(of_st21nfca_i2c_match),
		.acpi_match_table = ACPI_PTR(st21nfca_hci_i2c_acpi_match),
	},
	.probe = st21nfca_hci_i2c_probe,
	.id_table = st21nfca_hci_i2c_id_table,
	.remove = st21nfca_hci_i2c_remove,
};
module_i2c_driver(st21nfca_hci_i2c_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION(DRIVER_DESC);