2 * I2C Link Layer for ST21NFCA HCI based Driver
3 * Copyright (C) 2014 STMicroelectronics SAS. All rights reserved.
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.
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.
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/>.
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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>
34 #include <net/nfc/hci.h>
35 #include <net/nfc/llc.h>
36 #include <net/nfc/nfc.h>
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.
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
49 #define ST21NFCA_SOF_EOF 0x7e
50 #define ST21NFCA_BYTE_STUFFING_MASK 0x20
51 #define ST21NFCA_ESCAPE_BYTE_STUFFING 0x7d
54 #define ST21NFCA_FRAME_HEADROOM 2
56 /* 2 bytes crc + EOF */
57 #define ST21NFCA_FRAME_TAILROOM 3
58 #define IS_START_OF_FRAME(buf) (buf[0] == ST21NFCA_SOF_EOF && \
61 #define ST21NFCA_HCI_I2C_DRIVER_NAME "st21nfca_hci_i2c"
63 static struct i2c_device_id st21nfca_hci_i2c_id_table[] = {
64 {ST21NFCA_HCI_DRIVER_NAME, 0},
68 MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table);
70 struct st21nfca_i2c_phy {
71 struct i2c_client *i2c_dev;
72 struct nfc_hci_dev *hdev;
74 unsigned int gpio_ena;
75 unsigned int irq_polarity;
77 struct st21nfca_se_status se_status;
79 struct sk_buff *pending_skb;
82 * crc might have fail because i2c macro
83 * is disable due to other interface activity
91 * < 0 if hardware error occured (e.g. i2c err)
92 * and prevents normal operation.
95 struct mutex phy_lock;
98 static u8 len_seq[] = { 16, 24, 12, 29 };
99 static u16 wait_tab[] = { 2, 3, 5, 15, 20, 40};
101 #define I2C_DUMP_SKB(info, skb) \
103 pr_debug("%s:\n", info); \
104 print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
105 16, 1, (skb)->data, (skb)->len, 0); \
109 * In order to get the CLF in a known state we generate an internal reboot
110 * using a proprietary command.
111 * Once the reboot is completed, we expect to receive a ST21NFCA_SOF_EOF
114 static int st21nfca_hci_platform_init(struct st21nfca_i2c_phy *phy)
116 u16 wait_reboot[] = { 50, 300, 1000 };
117 char reboot_cmd[] = { 0x7E, 0x66, 0x48, 0xF6, 0x7E };
118 u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE];
121 for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
122 r = i2c_master_send(phy->i2c_dev, reboot_cmd,
125 msleep(wait_reboot[i]);
130 /* CLF is spending about 20ms to do an internal reboot */
133 for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
134 r = i2c_master_recv(phy->i2c_dev, tmp,
135 ST21NFCA_HCI_LLC_MAX_SIZE);
137 msleep(wait_reboot[i]);
142 for (i = 0; i < ST21NFCA_HCI_LLC_MAX_SIZE &&
143 tmp[i] == ST21NFCA_SOF_EOF; i++)
146 if (r != ST21NFCA_HCI_LLC_MAX_SIZE)
149 usleep_range(1000, 1500);
153 static int st21nfca_hci_i2c_enable(void *phy_id)
155 struct st21nfca_i2c_phy *phy = phy_id;
157 gpio_set_value(phy->gpio_ena, 1);
159 phy->run_mode = ST21NFCA_HCI_MODE;
161 usleep_range(10000, 15000);
166 static void st21nfca_hci_i2c_disable(void *phy_id)
168 struct st21nfca_i2c_phy *phy = phy_id;
171 gpio_set_value(phy->gpio_ena, 0);
176 static void st21nfca_hci_add_len_crc(struct sk_buff *skb)
181 *skb_push(skb, 1) = 0;
183 crc = crc_ccitt(0xffff, skb->data, skb->len);
187 *skb_put(skb, 1) = tmp;
189 tmp = (crc >> 8) & 0x00ff;
190 *skb_put(skb, 1) = tmp;
193 static void st21nfca_hci_remove_len_crc(struct sk_buff *skb)
195 skb_pull(skb, ST21NFCA_FRAME_HEADROOM);
196 skb_trim(skb, skb->len - ST21NFCA_FRAME_TAILROOM);
200 * Writing a frame must not return the number of written bytes.
201 * It must return either zero for success, or <0 for error.
202 * In addition, it must not alter the skb
204 static int st21nfca_hci_i2c_write(void *phy_id, struct sk_buff *skb)
207 struct st21nfca_i2c_phy *phy = phy_id;
208 struct i2c_client *client = phy->i2c_dev;
209 u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE * 2];
211 I2C_DUMP_SKB("st21nfca_hci_i2c_write", skb);
214 if (phy->hard_fault != 0)
215 return phy->hard_fault;
218 * Compute CRC before byte stuffing computation on frame
219 * Note st21nfca_hci_add_len_crc is doing a byte stuffing
222 st21nfca_hci_add_len_crc(skb);
224 /* add ST21NFCA_SOF_EOF on tail */
225 *skb_put(skb, 1) = ST21NFCA_SOF_EOF;
226 /* add ST21NFCA_SOF_EOF on head */
227 *skb_push(skb, 1) = ST21NFCA_SOF_EOF;
230 * Compute byte stuffing
231 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING
232 * insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)
233 * xor byte with ST21NFCA_BYTE_STUFFING_MASK
235 tmp[0] = skb->data[0];
236 for (i = 1, j = 1; i < skb->len - 1; i++, j++) {
237 if (skb->data[i] == ST21NFCA_SOF_EOF
238 || skb->data[i] == ST21NFCA_ESCAPE_BYTE_STUFFING) {
239 tmp[j] = ST21NFCA_ESCAPE_BYTE_STUFFING;
241 tmp[j] = skb->data[i] ^ ST21NFCA_BYTE_STUFFING_MASK;
243 tmp[j] = skb->data[i];
246 tmp[j] = skb->data[i];
251 * Try 3 times to send data with delay between each
253 mutex_lock(&phy->phy_lock);
254 for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++) {
255 r = i2c_master_send(client, tmp, j);
259 mutex_unlock(&phy->phy_lock);
268 st21nfca_hci_remove_len_crc(skb);
273 static int get_frame_size(u8 *buf, int buflen)
277 if (buf[len + 1] == ST21NFCA_SOF_EOF)
280 for (len = 1; len < buflen && buf[len] != ST21NFCA_SOF_EOF; len++)
286 static int check_crc(u8 *buf, int buflen)
290 crc = crc_ccitt(0xffff, buf, buflen - 2);
293 if (buf[buflen - 2] != (crc & 0xff) || buf[buflen - 1] != (crc >> 8)) {
294 pr_err(ST21NFCA_HCI_DRIVER_NAME
295 ": CRC error 0x%x != 0x%x 0x%x\n", crc, buf[buflen - 1],
298 pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
299 print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
300 16, 2, buf, buflen, false);
307 * Prepare received data for upper layer.
308 * Received data include byte stuffing, crc and sof/eof
309 * which is not usable by hci part.
311 * frame size without sof/eof, header and byte stuffing
312 * -EBADMSG : frame was incorrect and discarded
314 static int st21nfca_hci_i2c_repack(struct sk_buff *skb)
318 if (skb->len < 1 || (skb->len > 1 && skb->data[1] != 0))
321 size = get_frame_size(skb->data, skb->len);
324 /* remove ST21NFCA byte stuffing for upper layer */
325 for (i = 1, j = 0; i < skb->len; i++) {
326 if (skb->data[i + j] ==
327 (u8) ST21NFCA_ESCAPE_BYTE_STUFFING) {
328 skb->data[i] = skb->data[i + j + 1]
329 | ST21NFCA_BYTE_STUFFING_MASK;
333 skb->data[i] = skb->data[i + j];
335 /* remove byte stuffing useless byte */
336 skb_trim(skb, i - j);
337 /* remove ST21NFCA_SOF_EOF from head */
340 r = check_crc(skb->data, skb->len);
346 /* remove headbyte */
348 /* remove crc. Byte Stuffing is already removed here */
349 skb_trim(skb, skb->len - 2);
356 * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees
357 * that i2c bus will be flushed and that next read will start on a new frame.
358 * returned skb contains only LLC header and payload.
360 * frame size : if received frame is complete (find ST21NFCA_SOF_EOF at
362 * -EAGAIN : if received frame is incomplete (not find ST21NFCA_SOF_EOF
364 * -EREMOTEIO : i2c read error (fatal)
365 * -EBADMSG : frame was incorrect and discarded
366 * (value returned from st21nfca_hci_i2c_repack)
367 * -EIO : if no ST21NFCA_SOF_EOF is found after reaching
368 * the read length end sequence
370 static int st21nfca_hci_i2c_read(struct st21nfca_i2c_phy *phy,
375 u8 buf[ST21NFCA_HCI_LLC_MAX_PAYLOAD];
376 struct i2c_client *client = phy->i2c_dev;
378 if (phy->current_read_len < ARRAY_SIZE(len_seq)) {
379 len = len_seq[phy->current_read_len];
383 * Operation on I2C interface may fail in case of operation on
384 * RF or SWP interface
387 mutex_lock(&phy->phy_lock);
388 for (i = 0; i < ARRAY_SIZE(wait_tab) && r <= 0; i++) {
389 r = i2c_master_recv(client, buf, len);
393 mutex_unlock(&phy->phy_lock);
396 phy->current_read_len = 0;
401 * The first read sequence does not start with SOF.
402 * Data is corrupeted so we drop it.
404 if (!phy->current_read_len && !IS_START_OF_FRAME(buf)) {
406 phy->current_read_len = 0;
408 } else if (phy->current_read_len && IS_START_OF_FRAME(buf)) {
410 * Previous frame transmission was interrupted and
411 * the frame got repeated.
412 * Received frame start with ST21NFCA_SOF_EOF + 00.
415 phy->current_read_len = 0;
418 memcpy(skb_put(skb, len), buf, len);
420 if (skb->data[skb->len - 1] == ST21NFCA_SOF_EOF) {
421 phy->current_read_len = 0;
422 return st21nfca_hci_i2c_repack(skb);
424 phy->current_read_len++;
431 * Reads an shdlc frame from the chip. This is not as straightforward as it
432 * seems. The frame format is data-crc, and corruption can occur anywhere
433 * while transiting on i2c bus, such that we could read an invalid data.
434 * The tricky case is when we read a corrupted data or crc. We must detect
435 * this here in order to determine that data can be transmitted to the hci
436 * core. This is the reason why we check the crc here.
437 * The CLF will repeat a frame until we send a RR on that frame.
439 * On ST21NFCA, IRQ goes in idle when read starts. As no size information are
440 * available in the incoming data, other IRQ might come. Every IRQ will trigger
441 * a read sequence with different length and will fill the current frame.
442 * The reception is complete once we reach a ST21NFCA_SOF_EOF.
444 static irqreturn_t st21nfca_hci_irq_thread_fn(int irq, void *phy_id)
446 struct st21nfca_i2c_phy *phy = phy_id;
447 struct i2c_client *client;
451 if (!phy || irq != phy->i2c_dev->irq) {
456 client = phy->i2c_dev;
457 dev_dbg(&client->dev, "IRQ\n");
459 if (phy->hard_fault != 0)
462 r = st21nfca_hci_i2c_read(phy, phy->pending_skb);
463 if (r == -EREMOTEIO) {
466 nfc_hci_recv_frame(phy->hdev, NULL);
469 } else if (r == -EAGAIN || r == -EIO) {
471 } else if (r == -EBADMSG && phy->crc_trials < ARRAY_SIZE(wait_tab)) {
473 * With ST21NFCA, only one interface (I2C, RF or SWP)
474 * may be active at a time.
475 * Having incorrect crc is usually due to i2c macrocell
476 * deactivation in the middle of a transmission.
477 * It may generate corrupted data on i2c.
478 * We give sometime to get i2c back.
479 * The complete frame will be repeated.
481 msleep(wait_tab[phy->crc_trials]);
483 phy->current_read_len = 0;
484 kfree_skb(phy->pending_skb);
487 * We succeeded to read data from the CLF and
491 nfc_hci_recv_frame(phy->hdev, phy->pending_skb);
494 kfree_skb(phy->pending_skb);
497 phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
498 if (phy->pending_skb == NULL) {
499 phy->hard_fault = -ENOMEM;
500 nfc_hci_recv_frame(phy->hdev, NULL);
506 static struct nfc_phy_ops i2c_phy_ops = {
507 .write = st21nfca_hci_i2c_write,
508 .enable = st21nfca_hci_i2c_enable,
509 .disable = st21nfca_hci_i2c_disable,
513 static int st21nfca_hci_i2c_of_request_resources(struct i2c_client *client)
515 struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);
516 struct device_node *pp;
520 pp = client->dev.of_node;
524 /* Get GPIO from device tree */
525 gpio = of_get_named_gpio(pp, "enable-gpios", 0);
527 nfc_err(&client->dev, "Failed to retrieve enable-gpios from device tree\n");
531 /* GPIO request and configuration */
532 r = devm_gpio_request_one(&client->dev, gpio, GPIOF_OUT_INIT_HIGH,
535 nfc_err(&client->dev, "Failed to request enable pin\n");
539 phy->gpio_ena = gpio;
541 phy->irq_polarity = irq_get_trigger_type(client->irq);
543 phy->se_status.is_ese_present =
544 of_property_read_bool(pp, "ese-present");
545 phy->se_status.is_uicc_present =
546 of_property_read_bool(pp, "uicc-present");
551 static int st21nfca_hci_i2c_of_request_resources(struct i2c_client *client)
557 static int st21nfca_hci_i2c_request_resources(struct i2c_client *client)
559 struct st21nfca_nfc_platform_data *pdata;
560 struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);
563 pdata = client->dev.platform_data;
565 nfc_err(&client->dev, "No platform data\n");
569 /* store for later use */
570 phy->gpio_ena = pdata->gpio_ena;
571 phy->irq_polarity = pdata->irq_polarity;
573 if (phy->gpio_ena > 0) {
574 r = devm_gpio_request_one(&client->dev, phy->gpio_ena,
575 GPIOF_OUT_INIT_HIGH, "clf_enable");
577 pr_err("%s : ena gpio_request failed\n", __FILE__);
582 phy->se_status.is_ese_present = pdata->is_ese_present;
583 phy->se_status.is_uicc_present = pdata->is_uicc_present;
588 static int st21nfca_hci_i2c_probe(struct i2c_client *client,
589 const struct i2c_device_id *id)
591 struct st21nfca_i2c_phy *phy;
592 struct st21nfca_nfc_platform_data *pdata;
595 dev_dbg(&client->dev, "%s\n", __func__);
596 dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
598 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
599 nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
603 phy = devm_kzalloc(&client->dev, sizeof(struct st21nfca_i2c_phy),
608 phy->i2c_dev = client;
609 phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
610 if (phy->pending_skb == NULL)
613 phy->current_read_len = 0;
615 mutex_init(&phy->phy_lock);
616 i2c_set_clientdata(client, phy);
618 pdata = client->dev.platform_data;
619 if (!pdata && client->dev.of_node) {
620 r = st21nfca_hci_i2c_of_request_resources(client);
622 nfc_err(&client->dev, "No platform data\n");
626 r = st21nfca_hci_i2c_request_resources(client);
628 nfc_err(&client->dev, "Cannot get platform resources\n");
632 nfc_err(&client->dev, "st21nfca platform resources not available\n");
636 r = st21nfca_hci_platform_init(phy);
638 nfc_err(&client->dev, "Unable to reboot st21nfca\n");
642 r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
643 st21nfca_hci_irq_thread_fn,
644 phy->irq_polarity | IRQF_ONESHOT,
645 ST21NFCA_HCI_DRIVER_NAME, phy);
647 nfc_err(&client->dev, "Unable to register IRQ handler\n");
651 return st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
652 ST21NFCA_FRAME_HEADROOM,
653 ST21NFCA_FRAME_TAILROOM,
654 ST21NFCA_HCI_LLC_MAX_PAYLOAD,
659 static int st21nfca_hci_i2c_remove(struct i2c_client *client)
661 struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);
663 dev_dbg(&client->dev, "%s\n", __func__);
665 st21nfca_hci_remove(phy->hdev);
668 st21nfca_hci_i2c_disable(phy);
674 static const struct of_device_id of_st21nfca_i2c_match[] = {
675 { .compatible = "st,st21nfca-i2c", },
676 { .compatible = "st,st21nfca_i2c", },
679 MODULE_DEVICE_TABLE(of, of_st21nfca_i2c_match);
682 static struct i2c_driver st21nfca_hci_i2c_driver = {
684 .owner = THIS_MODULE,
685 .name = ST21NFCA_HCI_I2C_DRIVER_NAME,
686 .of_match_table = of_match_ptr(of_st21nfca_i2c_match),
688 .probe = st21nfca_hci_i2c_probe,
689 .id_table = st21nfca_hci_i2c_id_table,
690 .remove = st21nfca_hci_i2c_remove,
693 module_i2c_driver(st21nfca_hci_i2c_driver);
695 MODULE_LICENSE("GPL");
696 MODULE_DESCRIPTION(DRIVER_DESC);