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/consumer.h>
24 #include <linux/of_irq.h>
25 #include <linux/of_gpio.h>
26 #include <linux/acpi.h>
27 #include <linux/interrupt.h>
28 #include <linux/delay.h>
29 #include <linux/nfc.h>
30 #include <linux/firmware.h>
31
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_DRIVER_NAME "st21nfca_hci"
62 #define ST21NFCA_HCI_I2C_DRIVER_NAME "st21nfca_hci_i2c"
63
64 struct st21nfca_i2c_phy {
65 struct i2c_client *i2c_dev;
66 struct nfc_hci_dev *hdev;
67
68 struct gpio_desc *gpiod_ena;
69 struct st21nfca_se_status se_status;
70
71 struct sk_buff *pending_skb;
72 int current_read_len;
73 /*
74 * crc might have fail because i2c macro
75 * is disable due to other interface activity
76 */
77 int crc_trials;
78
79 int powered;
80 int run_mode;
81
82 /*
83 * < 0 if hardware error occured (e.g. i2c err)
84 * and prevents normal operation.
85 */
86 int hard_fault;
87 struct mutex phy_lock;
88 };
89
90 static u8 len_seq[] = { 16, 24, 12, 29 };
91 static u16 wait_tab[] = { 2, 3, 5, 15, 20, 40};
92
93 #define I2C_DUMP_SKB(info, skb) \
94 do { \
95 pr_debug("%s:\n", info); \
96 print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
97 16, 1, (skb)->data, (skb)->len, 0); \
98 } while (0)
99
100 /*
101 * In order to get the CLF in a known state we generate an internal reboot
102 * using a proprietary command.
103 * Once the reboot is completed, we expect to receive a ST21NFCA_SOF_EOF
104 * fill buffer.
105 */
st21nfca_hci_platform_init(struct st21nfca_i2c_phy * phy)106 static int st21nfca_hci_platform_init(struct st21nfca_i2c_phy *phy)
107 {
108 u16 wait_reboot[] = { 50, 300, 1000 };
109 char reboot_cmd[] = { 0x7E, 0x66, 0x48, 0xF6, 0x7E };
110 u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE];
111 int i, r = -1;
112
113 for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
114 r = i2c_master_send(phy->i2c_dev, reboot_cmd,
115 sizeof(reboot_cmd));
116 if (r < 0)
117 msleep(wait_reboot[i]);
118 }
119 if (r < 0)
120 return r;
121
122 /* CLF is spending about 20ms to do an internal reboot */
123 msleep(20);
124 r = -1;
125 for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
126 r = i2c_master_recv(phy->i2c_dev, tmp,
127 ST21NFCA_HCI_LLC_MAX_SIZE);
128 if (r < 0)
129 msleep(wait_reboot[i]);
130 }
131 if (r < 0)
132 return r;
133
134 for (i = 0; i < ST21NFCA_HCI_LLC_MAX_SIZE &&
135 tmp[i] == ST21NFCA_SOF_EOF; i++)
136 ;
137
138 if (r != ST21NFCA_HCI_LLC_MAX_SIZE)
139 return -ENODEV;
140
141 usleep_range(1000, 1500);
142 return 0;
143 }
144
st21nfca_hci_i2c_enable(void * phy_id)145 static int st21nfca_hci_i2c_enable(void *phy_id)
146 {
147 struct st21nfca_i2c_phy *phy = phy_id;
148
149 gpiod_set_value(phy->gpiod_ena, 1);
150 phy->powered = 1;
151 phy->run_mode = ST21NFCA_HCI_MODE;
152
153 usleep_range(10000, 15000);
154
155 return 0;
156 }
157
st21nfca_hci_i2c_disable(void * phy_id)158 static void st21nfca_hci_i2c_disable(void *phy_id)
159 {
160 struct st21nfca_i2c_phy *phy = phy_id;
161
162 gpiod_set_value(phy->gpiod_ena, 0);
163
164 phy->powered = 0;
165 }
166
st21nfca_hci_add_len_crc(struct sk_buff * skb)167 static void st21nfca_hci_add_len_crc(struct sk_buff *skb)
168 {
169 u16 crc;
170 u8 tmp;
171
172 *(u8 *)skb_push(skb, 1) = 0;
173
174 crc = crc_ccitt(0xffff, skb->data, skb->len);
175 crc = ~crc;
176
177 tmp = crc & 0x00ff;
178 skb_put_u8(skb, tmp);
179
180 tmp = (crc >> 8) & 0x00ff;
181 skb_put_u8(skb, tmp);
182 }
183
st21nfca_hci_remove_len_crc(struct sk_buff * skb)184 static void st21nfca_hci_remove_len_crc(struct sk_buff *skb)
185 {
186 skb_pull(skb, ST21NFCA_FRAME_HEADROOM);
187 skb_trim(skb, skb->len - ST21NFCA_FRAME_TAILROOM);
188 }
189
190 /*
191 * Writing a frame must not return the number of written bytes.
192 * It must return either zero for success, or <0 for error.
193 * In addition, it must not alter the skb
194 */
st21nfca_hci_i2c_write(void * phy_id,struct sk_buff * skb)195 static int st21nfca_hci_i2c_write(void *phy_id, struct sk_buff *skb)
196 {
197 int r = -1, i, j;
198 struct st21nfca_i2c_phy *phy = phy_id;
199 struct i2c_client *client = phy->i2c_dev;
200 u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE * 2];
201
202 I2C_DUMP_SKB("st21nfca_hci_i2c_write", skb);
203
204 if (phy->hard_fault != 0)
205 return phy->hard_fault;
206
207 /*
208 * Compute CRC before byte stuffing computation on frame
209 * Note st21nfca_hci_add_len_crc is doing a byte stuffing
210 * on its own value
211 */
212 st21nfca_hci_add_len_crc(skb);
213
214 /* add ST21NFCA_SOF_EOF on tail */
215 skb_put_u8(skb, ST21NFCA_SOF_EOF);
216 /* add ST21NFCA_SOF_EOF on head */
217 *(u8 *)skb_push(skb, 1) = ST21NFCA_SOF_EOF;
218
219 /*
220 * Compute byte stuffing
221 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING
222 * insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)
223 * xor byte with ST21NFCA_BYTE_STUFFING_MASK
224 */
225 tmp[0] = skb->data[0];
226 for (i = 1, j = 1; i < skb->len - 1; i++, j++) {
227 if (skb->data[i] == ST21NFCA_SOF_EOF
228 || skb->data[i] == ST21NFCA_ESCAPE_BYTE_STUFFING) {
229 tmp[j] = ST21NFCA_ESCAPE_BYTE_STUFFING;
230 j++;
231 tmp[j] = skb->data[i] ^ ST21NFCA_BYTE_STUFFING_MASK;
232 } else {
233 tmp[j] = skb->data[i];
234 }
235 }
236 tmp[j] = skb->data[i];
237 j++;
238
239 /*
240 * Manage sleep mode
241 * Try 3 times to send data with delay between each
242 */
243 mutex_lock(&phy->phy_lock);
244 for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++) {
245 r = i2c_master_send(client, tmp, j);
246 if (r < 0)
247 msleep(wait_tab[i]);
248 }
249 mutex_unlock(&phy->phy_lock);
250
251 if (r >= 0) {
252 if (r != j)
253 r = -EREMOTEIO;
254 else
255 r = 0;
256 }
257
258 st21nfca_hci_remove_len_crc(skb);
259
260 return r;
261 }
262
get_frame_size(u8 * buf,int buflen)263 static int get_frame_size(u8 *buf, int buflen)
264 {
265 int len = 0;
266
267 if (buf[len + 1] == ST21NFCA_SOF_EOF)
268 return 0;
269
270 for (len = 1; len < buflen && buf[len] != ST21NFCA_SOF_EOF; len++)
271 ;
272
273 return len;
274 }
275
check_crc(u8 * buf,int buflen)276 static int check_crc(u8 *buf, int buflen)
277 {
278 u16 crc;
279
280 crc = crc_ccitt(0xffff, buf, buflen - 2);
281 crc = ~crc;
282
283 if (buf[buflen - 2] != (crc & 0xff) || buf[buflen - 1] != (crc >> 8)) {
284 pr_err(ST21NFCA_HCI_DRIVER_NAME
285 ": CRC error 0x%x != 0x%x 0x%x\n", crc, buf[buflen - 1],
286 buf[buflen - 2]);
287
288 pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
289 print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
290 16, 2, buf, buflen, false);
291 return -EPERM;
292 }
293 return 0;
294 }
295
296 /*
297 * Prepare received data for upper layer.
298 * Received data include byte stuffing, crc and sof/eof
299 * which is not usable by hci part.
300 * returns:
301 * frame size without sof/eof, header and byte stuffing
302 * -EBADMSG : frame was incorrect and discarded
303 */
st21nfca_hci_i2c_repack(struct sk_buff * skb)304 static int st21nfca_hci_i2c_repack(struct sk_buff *skb)
305 {
306 int i, j, r, size;
307
308 if (skb->len < 1 || (skb->len > 1 && skb->data[1] != 0))
309 return -EBADMSG;
310
311 size = get_frame_size(skb->data, skb->len);
312 if (size > 0) {
313 skb_trim(skb, size);
314 /* remove ST21NFCA byte stuffing for upper layer */
315 for (i = 1, j = 0; i < skb->len; i++) {
316 if (skb->data[i + j] ==
317 (u8) ST21NFCA_ESCAPE_BYTE_STUFFING) {
318 skb->data[i] = skb->data[i + j + 1]
319 | ST21NFCA_BYTE_STUFFING_MASK;
320 i++;
321 j++;
322 }
323 skb->data[i] = skb->data[i + j];
324 }
325 /* remove byte stuffing useless byte */
326 skb_trim(skb, i - j);
327 /* remove ST21NFCA_SOF_EOF from head */
328 skb_pull(skb, 1);
329
330 r = check_crc(skb->data, skb->len);
331 if (r != 0) {
332 i = 0;
333 return -EBADMSG;
334 }
335
336 /* remove headbyte */
337 skb_pull(skb, 1);
338 /* remove crc. Byte Stuffing is already removed here */
339 skb_trim(skb, skb->len - 2);
340 return skb->len;
341 }
342 return 0;
343 }
344
345 /*
346 * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees
347 * that i2c bus will be flushed and that next read will start on a new frame.
348 * returned skb contains only LLC header and payload.
349 * returns:
350 * frame size : if received frame is complete (find ST21NFCA_SOF_EOF at
351 * end of read)
352 * -EAGAIN : if received frame is incomplete (not find ST21NFCA_SOF_EOF
353 * at end of read)
354 * -EREMOTEIO : i2c read error (fatal)
355 * -EBADMSG : frame was incorrect and discarded
356 * (value returned from st21nfca_hci_i2c_repack)
357 * -EIO : if no ST21NFCA_SOF_EOF is found after reaching
358 * the read length end sequence
359 */
st21nfca_hci_i2c_read(struct st21nfca_i2c_phy * phy,struct sk_buff * skb)360 static int st21nfca_hci_i2c_read(struct st21nfca_i2c_phy *phy,
361 struct sk_buff *skb)
362 {
363 int r, i;
364 u8 len;
365 u8 buf[ST21NFCA_HCI_LLC_MAX_PAYLOAD];
366 struct i2c_client *client = phy->i2c_dev;
367
368 if (phy->current_read_len < ARRAY_SIZE(len_seq)) {
369 len = len_seq[phy->current_read_len];
370
371 /*
372 * Add retry mecanism
373 * Operation on I2C interface may fail in case of operation on
374 * RF or SWP interface
375 */
376 r = 0;
377 mutex_lock(&phy->phy_lock);
378 for (i = 0; i < ARRAY_SIZE(wait_tab) && r <= 0; i++) {
379 r = i2c_master_recv(client, buf, len);
380 if (r < 0)
381 msleep(wait_tab[i]);
382 }
383 mutex_unlock(&phy->phy_lock);
384
385 if (r != len) {
386 phy->current_read_len = 0;
387 return -EREMOTEIO;
388 }
389
390 /*
391 * The first read sequence does not start with SOF.
392 * Data is corrupeted so we drop it.
393 */
394 if (!phy->current_read_len && !IS_START_OF_FRAME(buf)) {
395 skb_trim(skb, 0);
396 phy->current_read_len = 0;
397 return -EIO;
398 } else if (phy->current_read_len && IS_START_OF_FRAME(buf)) {
399 /*
400 * Previous frame transmission was interrupted and
401 * the frame got repeated.
402 * Received frame start with ST21NFCA_SOF_EOF + 00.
403 */
404 skb_trim(skb, 0);
405 phy->current_read_len = 0;
406 }
407
408 skb_put_data(skb, buf, len);
409
410 if (skb->data[skb->len - 1] == ST21NFCA_SOF_EOF) {
411 phy->current_read_len = 0;
412 return st21nfca_hci_i2c_repack(skb);
413 }
414 phy->current_read_len++;
415 return -EAGAIN;
416 }
417 return -EIO;
418 }
419
420 /*
421 * Reads an shdlc frame from the chip. This is not as straightforward as it
422 * seems. The frame format is data-crc, and corruption can occur anywhere
423 * while transiting on i2c bus, such that we could read an invalid data.
424 * The tricky case is when we read a corrupted data or crc. We must detect
425 * this here in order to determine that data can be transmitted to the hci
426 * core. This is the reason why we check the crc here.
427 * The CLF will repeat a frame until we send a RR on that frame.
428 *
429 * On ST21NFCA, IRQ goes in idle when read starts. As no size information are
430 * available in the incoming data, other IRQ might come. Every IRQ will trigger
431 * a read sequence with different length and will fill the current frame.
432 * The reception is complete once we reach a ST21NFCA_SOF_EOF.
433 */
st21nfca_hci_irq_thread_fn(int irq,void * phy_id)434 static irqreturn_t st21nfca_hci_irq_thread_fn(int irq, void *phy_id)
435 {
436 struct st21nfca_i2c_phy *phy = phy_id;
437 struct i2c_client *client;
438
439 int r;
440
441 if (!phy || irq != phy->i2c_dev->irq) {
442 WARN_ON_ONCE(1);
443 return IRQ_NONE;
444 }
445
446 client = phy->i2c_dev;
447 dev_dbg(&client->dev, "IRQ\n");
448
449 if (phy->hard_fault != 0)
450 return IRQ_HANDLED;
451
452 r = st21nfca_hci_i2c_read(phy, phy->pending_skb);
453 if (r == -EREMOTEIO) {
454 phy->hard_fault = r;
455
456 nfc_hci_recv_frame(phy->hdev, NULL);
457
458 return IRQ_HANDLED;
459 } else if (r == -EAGAIN || r == -EIO) {
460 return IRQ_HANDLED;
461 } else if (r == -EBADMSG && phy->crc_trials < ARRAY_SIZE(wait_tab)) {
462 /*
463 * With ST21NFCA, only one interface (I2C, RF or SWP)
464 * may be active at a time.
465 * Having incorrect crc is usually due to i2c macrocell
466 * deactivation in the middle of a transmission.
467 * It may generate corrupted data on i2c.
468 * We give sometime to get i2c back.
469 * The complete frame will be repeated.
470 */
471 msleep(wait_tab[phy->crc_trials]);
472 phy->crc_trials++;
473 phy->current_read_len = 0;
474 kfree_skb(phy->pending_skb);
475 } else if (r > 0) {
476 /*
477 * We succeeded to read data from the CLF and
478 * data is valid.
479 * Reset counter.
480 */
481 nfc_hci_recv_frame(phy->hdev, phy->pending_skb);
482 phy->crc_trials = 0;
483 } else {
484 kfree_skb(phy->pending_skb);
485 }
486
487 phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
488 if (phy->pending_skb == NULL) {
489 phy->hard_fault = -ENOMEM;
490 nfc_hci_recv_frame(phy->hdev, NULL);
491 }
492
493 return IRQ_HANDLED;
494 }
495
496 static struct nfc_phy_ops i2c_phy_ops = {
497 .write = st21nfca_hci_i2c_write,
498 .enable = st21nfca_hci_i2c_enable,
499 .disable = st21nfca_hci_i2c_disable,
500 };
501
502 static const struct acpi_gpio_params enable_gpios = { 1, 0, false };
503
504 static const struct acpi_gpio_mapping acpi_st21nfca_gpios[] = {
505 { "enable-gpios", &enable_gpios, 1 },
506 {},
507 };
508
st21nfca_hci_i2c_probe(struct i2c_client * client,const struct i2c_device_id * id)509 static int st21nfca_hci_i2c_probe(struct i2c_client *client,
510 const struct i2c_device_id *id)
511 {
512 struct device *dev = &client->dev;
513 struct st21nfca_i2c_phy *phy;
514 int r;
515
516 dev_dbg(&client->dev, "%s\n", __func__);
517 dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
518
519 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
520 nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
521 return -ENODEV;
522 }
523
524 phy = devm_kzalloc(&client->dev, sizeof(struct st21nfca_i2c_phy),
525 GFP_KERNEL);
526 if (!phy)
527 return -ENOMEM;
528
529 phy->i2c_dev = client;
530 phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
531 if (phy->pending_skb == NULL)
532 return -ENOMEM;
533
534 phy->current_read_len = 0;
535 phy->crc_trials = 0;
536 mutex_init(&phy->phy_lock);
537 i2c_set_clientdata(client, phy);
538
539 r = devm_acpi_dev_add_driver_gpios(dev, acpi_st21nfca_gpios);
540 if (r)
541 dev_dbg(dev, "Unable to add GPIO mapping table\n");
542
543 /* Get EN GPIO from resource provider */
544 phy->gpiod_ena = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
545 if (IS_ERR(phy->gpiod_ena)) {
546 nfc_err(dev, "Unable to get ENABLE GPIO\n");
547 return PTR_ERR(phy->gpiod_ena);
548 }
549
550 phy->se_status.is_ese_present =
551 device_property_read_bool(&client->dev, "ese-present");
552 phy->se_status.is_uicc_present =
553 device_property_read_bool(&client->dev, "uicc-present");
554
555 r = st21nfca_hci_platform_init(phy);
556 if (r < 0) {
557 nfc_err(&client->dev, "Unable to reboot st21nfca\n");
558 return r;
559 }
560
561 r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
562 st21nfca_hci_irq_thread_fn,
563 IRQF_ONESHOT,
564 ST21NFCA_HCI_DRIVER_NAME, phy);
565 if (r < 0) {
566 nfc_err(&client->dev, "Unable to register IRQ handler\n");
567 return r;
568 }
569
570 return st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
571 ST21NFCA_FRAME_HEADROOM,
572 ST21NFCA_FRAME_TAILROOM,
573 ST21NFCA_HCI_LLC_MAX_PAYLOAD,
574 &phy->hdev,
575 &phy->se_status);
576 }
577
st21nfca_hci_i2c_remove(struct i2c_client * client)578 static int st21nfca_hci_i2c_remove(struct i2c_client *client)
579 {
580 struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);
581
582 dev_dbg(&client->dev, "%s\n", __func__);
583
584 st21nfca_hci_remove(phy->hdev);
585
586 if (phy->powered)
587 st21nfca_hci_i2c_disable(phy);
588
589 return 0;
590 }
591
592 static const struct i2c_device_id st21nfca_hci_i2c_id_table[] = {
593 {ST21NFCA_HCI_DRIVER_NAME, 0},
594 {}
595 };
596 MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table);
597
598 static const struct acpi_device_id st21nfca_hci_i2c_acpi_match[] = {
599 {"SMO2100", 0},
600 {}
601 };
602 MODULE_DEVICE_TABLE(acpi, st21nfca_hci_i2c_acpi_match);
603
604 static const struct of_device_id of_st21nfca_i2c_match[] = {
605 { .compatible = "st,st21nfca-i2c", },
606 { .compatible = "st,st21nfca_i2c", },
607 {}
608 };
609 MODULE_DEVICE_TABLE(of, of_st21nfca_i2c_match);
610
611 static struct i2c_driver st21nfca_hci_i2c_driver = {
612 .driver = {
613 .name = ST21NFCA_HCI_I2C_DRIVER_NAME,
614 .of_match_table = of_match_ptr(of_st21nfca_i2c_match),
615 .acpi_match_table = ACPI_PTR(st21nfca_hci_i2c_acpi_match),
616 },
617 .probe = st21nfca_hci_i2c_probe,
618 .id_table = st21nfca_hci_i2c_id_table,
619 .remove = st21nfca_hci_i2c_remove,
620 };
621 module_i2c_driver(st21nfca_hci_i2c_driver);
622
623 MODULE_LICENSE("GPL");
624 MODULE_DESCRIPTION(DRIVER_DESC);
625
