1 // SPDX-License-Identifier: GPL-2.0-only
3 * I2C Link Layer for ST21NFCA HCI based Driver
4 * Copyright (C) 2014 STMicroelectronics SAS. All rights reserved.
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9 #include <linux/crc-ccitt.h>
10 #include <linux/module.h>
11 #include <linux/i2c.h>
12 #include <linux/gpio/consumer.h>
13 #include <linux/of_irq.h>
14 #include <linux/of_gpio.h>
15 #include <linux/acpi.h>
16 #include <linux/interrupt.h>
17 #include <linux/delay.h>
18 #include <linux/nfc.h>
19 #include <linux/firmware.h>
21 #include <asm/unaligned.h>
23 #include <net/nfc/hci.h>
24 #include <net/nfc/llc.h>
25 #include <net/nfc/nfc.h>
30 * Every frame starts with ST21NFCA_SOF_EOF and ends with ST21NFCA_SOF_EOF.
31 * Because ST21NFCA_SOF_EOF is a possible data value, there is a mecanism
32 * called byte stuffing has been introduced.
34 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING
35 * - insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)
36 * - xor byte with ST21NFCA_BYTE_STUFFING_MASK
38 #define ST21NFCA_SOF_EOF 0x7e
39 #define ST21NFCA_BYTE_STUFFING_MASK 0x20
40 #define ST21NFCA_ESCAPE_BYTE_STUFFING 0x7d
43 #define ST21NFCA_FRAME_HEADROOM 2
45 /* 2 bytes crc + EOF */
46 #define ST21NFCA_FRAME_TAILROOM 3
47 #define IS_START_OF_FRAME(buf) (buf[0] == ST21NFCA_SOF_EOF && \
50 #define ST21NFCA_HCI_DRIVER_NAME "st21nfca_hci"
51 #define ST21NFCA_HCI_I2C_DRIVER_NAME "st21nfca_hci_i2c"
53 struct st21nfca_i2c_phy {
54 struct i2c_client *i2c_dev;
55 struct nfc_hci_dev *hdev;
57 struct gpio_desc *gpiod_ena;
58 struct st21nfca_se_status se_status;
60 struct sk_buff *pending_skb;
63 * crc might have fail because i2c macro
64 * is disable due to other interface activity
72 * < 0 if hardware error occured (e.g. i2c err)
73 * and prevents normal operation.
76 struct mutex phy_lock;
79 static u8 len_seq[] = { 16, 24, 12, 29 };
80 static u16 wait_tab[] = { 2, 3, 5, 15, 20, 40};
82 #define I2C_DUMP_SKB(info, skb) \
84 pr_debug("%s:\n", info); \
85 print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
86 16, 1, (skb)->data, (skb)->len, 0); \
90 * In order to get the CLF in a known state we generate an internal reboot
91 * using a proprietary command.
92 * Once the reboot is completed, we expect to receive a ST21NFCA_SOF_EOF
95 static int st21nfca_hci_platform_init(struct st21nfca_i2c_phy *phy)
97 u16 wait_reboot[] = { 50, 300, 1000 };
98 char reboot_cmd[] = { 0x7E, 0x66, 0x48, 0xF6, 0x7E };
99 u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE];
102 for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
103 r = i2c_master_send(phy->i2c_dev, reboot_cmd,
106 msleep(wait_reboot[i]);
111 /* CLF is spending about 20ms to do an internal reboot */
114 for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) {
115 r = i2c_master_recv(phy->i2c_dev, tmp,
116 ST21NFCA_HCI_LLC_MAX_SIZE);
118 msleep(wait_reboot[i]);
123 for (i = 0; i < ST21NFCA_HCI_LLC_MAX_SIZE &&
124 tmp[i] == ST21NFCA_SOF_EOF; i++)
127 if (r != ST21NFCA_HCI_LLC_MAX_SIZE)
130 usleep_range(1000, 1500);
134 static int st21nfca_hci_i2c_enable(void *phy_id)
136 struct st21nfca_i2c_phy *phy = phy_id;
138 gpiod_set_value(phy->gpiod_ena, 1);
140 phy->run_mode = ST21NFCA_HCI_MODE;
142 usleep_range(10000, 15000);
147 static void st21nfca_hci_i2c_disable(void *phy_id)
149 struct st21nfca_i2c_phy *phy = phy_id;
151 gpiod_set_value(phy->gpiod_ena, 0);
156 static void st21nfca_hci_add_len_crc(struct sk_buff *skb)
161 *(u8 *)skb_push(skb, 1) = 0;
163 crc = crc_ccitt(0xffff, skb->data, skb->len);
167 skb_put_u8(skb, tmp);
169 tmp = (crc >> 8) & 0x00ff;
170 skb_put_u8(skb, tmp);
173 static void st21nfca_hci_remove_len_crc(struct sk_buff *skb)
175 skb_pull(skb, ST21NFCA_FRAME_HEADROOM);
176 skb_trim(skb, skb->len - ST21NFCA_FRAME_TAILROOM);
180 * Writing a frame must not return the number of written bytes.
181 * It must return either zero for success, or <0 for error.
182 * In addition, it must not alter the skb
184 static int st21nfca_hci_i2c_write(void *phy_id, struct sk_buff *skb)
187 struct st21nfca_i2c_phy *phy = phy_id;
188 struct i2c_client *client = phy->i2c_dev;
189 u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE * 2];
191 I2C_DUMP_SKB("st21nfca_hci_i2c_write", skb);
193 if (phy->hard_fault != 0)
194 return phy->hard_fault;
197 * Compute CRC before byte stuffing computation on frame
198 * Note st21nfca_hci_add_len_crc is doing a byte stuffing
201 st21nfca_hci_add_len_crc(skb);
203 /* add ST21NFCA_SOF_EOF on tail */
204 skb_put_u8(skb, ST21NFCA_SOF_EOF);
205 /* add ST21NFCA_SOF_EOF on head */
206 *(u8 *)skb_push(skb, 1) = ST21NFCA_SOF_EOF;
209 * Compute byte stuffing
210 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING
211 * insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)
212 * xor byte with ST21NFCA_BYTE_STUFFING_MASK
214 tmp[0] = skb->data[0];
215 for (i = 1, j = 1; i < skb->len - 1; i++, j++) {
216 if (skb->data[i] == ST21NFCA_SOF_EOF
217 || skb->data[i] == ST21NFCA_ESCAPE_BYTE_STUFFING) {
218 tmp[j] = ST21NFCA_ESCAPE_BYTE_STUFFING;
220 tmp[j] = skb->data[i] ^ ST21NFCA_BYTE_STUFFING_MASK;
222 tmp[j] = skb->data[i];
225 tmp[j] = skb->data[i];
230 * Try 3 times to send data with delay between each
232 mutex_lock(&phy->phy_lock);
233 for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++) {
234 r = i2c_master_send(client, tmp, j);
238 mutex_unlock(&phy->phy_lock);
247 st21nfca_hci_remove_len_crc(skb);
252 static int get_frame_size(u8 *buf, int buflen)
256 if (buf[len + 1] == ST21NFCA_SOF_EOF)
259 for (len = 1; len < buflen && buf[len] != ST21NFCA_SOF_EOF; len++)
265 static int check_crc(u8 *buf, int buflen)
269 crc = crc_ccitt(0xffff, buf, buflen - 2);
272 if (buf[buflen - 2] != (crc & 0xff) || buf[buflen - 1] != (crc >> 8)) {
273 pr_err(ST21NFCA_HCI_DRIVER_NAME
274 ": CRC error 0x%x != 0x%x 0x%x\n", crc, buf[buflen - 1],
277 pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
278 print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
279 16, 2, buf, buflen, false);
286 * Prepare received data for upper layer.
287 * Received data include byte stuffing, crc and sof/eof
288 * which is not usable by hci part.
290 * frame size without sof/eof, header and byte stuffing
291 * -EBADMSG : frame was incorrect and discarded
293 static int st21nfca_hci_i2c_repack(struct sk_buff *skb)
297 if (skb->len < 1 || (skb->len > 1 && skb->data[1] != 0))
300 size = get_frame_size(skb->data, skb->len);
303 /* remove ST21NFCA byte stuffing for upper layer */
304 for (i = 1, j = 0; i < skb->len; i++) {
305 if (skb->data[i + j] ==
306 (u8) ST21NFCA_ESCAPE_BYTE_STUFFING) {
307 skb->data[i] = skb->data[i + j + 1]
308 | ST21NFCA_BYTE_STUFFING_MASK;
312 skb->data[i] = skb->data[i + j];
314 /* remove byte stuffing useless byte */
315 skb_trim(skb, i - j);
316 /* remove ST21NFCA_SOF_EOF from head */
319 r = check_crc(skb->data, skb->len);
325 /* remove headbyte */
327 /* remove crc. Byte Stuffing is already removed here */
328 skb_trim(skb, skb->len - 2);
335 * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees
336 * that i2c bus will be flushed and that next read will start on a new frame.
337 * returned skb contains only LLC header and payload.
339 * frame size : if received frame is complete (find ST21NFCA_SOF_EOF at
341 * -EAGAIN : if received frame is incomplete (not find ST21NFCA_SOF_EOF
343 * -EREMOTEIO : i2c read error (fatal)
344 * -EBADMSG : frame was incorrect and discarded
345 * (value returned from st21nfca_hci_i2c_repack)
346 * -EIO : if no ST21NFCA_SOF_EOF is found after reaching
347 * the read length end sequence
349 static int st21nfca_hci_i2c_read(struct st21nfca_i2c_phy *phy,
354 u8 buf[ST21NFCA_HCI_LLC_MAX_PAYLOAD];
355 struct i2c_client *client = phy->i2c_dev;
357 if (phy->current_read_len < ARRAY_SIZE(len_seq)) {
358 len = len_seq[phy->current_read_len];
362 * Operation on I2C interface may fail in case of operation on
363 * RF or SWP interface
366 mutex_lock(&phy->phy_lock);
367 for (i = 0; i < ARRAY_SIZE(wait_tab) && r <= 0; i++) {
368 r = i2c_master_recv(client, buf, len);
372 mutex_unlock(&phy->phy_lock);
375 phy->current_read_len = 0;
380 * The first read sequence does not start with SOF.
381 * Data is corrupeted so we drop it.
383 if (!phy->current_read_len && !IS_START_OF_FRAME(buf)) {
385 phy->current_read_len = 0;
387 } else if (phy->current_read_len && IS_START_OF_FRAME(buf)) {
389 * Previous frame transmission was interrupted and
390 * the frame got repeated.
391 * Received frame start with ST21NFCA_SOF_EOF + 00.
394 phy->current_read_len = 0;
397 skb_put_data(skb, buf, len);
399 if (skb->data[skb->len - 1] == ST21NFCA_SOF_EOF) {
400 phy->current_read_len = 0;
401 return st21nfca_hci_i2c_repack(skb);
403 phy->current_read_len++;
410 * Reads an shdlc frame from the chip. This is not as straightforward as it
411 * seems. The frame format is data-crc, and corruption can occur anywhere
412 * while transiting on i2c bus, such that we could read an invalid data.
413 * The tricky case is when we read a corrupted data or crc. We must detect
414 * this here in order to determine that data can be transmitted to the hci
415 * core. This is the reason why we check the crc here.
416 * The CLF will repeat a frame until we send a RR on that frame.
418 * On ST21NFCA, IRQ goes in idle when read starts. As no size information are
419 * available in the incoming data, other IRQ might come. Every IRQ will trigger
420 * a read sequence with different length and will fill the current frame.
421 * The reception is complete once we reach a ST21NFCA_SOF_EOF.
423 static irqreturn_t st21nfca_hci_irq_thread_fn(int irq, void *phy_id)
425 struct st21nfca_i2c_phy *phy = phy_id;
426 struct i2c_client *client;
430 if (!phy || irq != phy->i2c_dev->irq) {
435 client = phy->i2c_dev;
436 dev_dbg(&client->dev, "IRQ\n");
438 if (phy->hard_fault != 0)
441 r = st21nfca_hci_i2c_read(phy, phy->pending_skb);
442 if (r == -EREMOTEIO) {
445 nfc_hci_recv_frame(phy->hdev, NULL);
448 } else if (r == -EAGAIN || r == -EIO) {
450 } else if (r == -EBADMSG && phy->crc_trials < ARRAY_SIZE(wait_tab)) {
452 * With ST21NFCA, only one interface (I2C, RF or SWP)
453 * may be active at a time.
454 * Having incorrect crc is usually due to i2c macrocell
455 * deactivation in the middle of a transmission.
456 * It may generate corrupted data on i2c.
457 * We give sometime to get i2c back.
458 * The complete frame will be repeated.
460 msleep(wait_tab[phy->crc_trials]);
462 phy->current_read_len = 0;
463 kfree_skb(phy->pending_skb);
466 * We succeeded to read data from the CLF and
470 nfc_hci_recv_frame(phy->hdev, phy->pending_skb);
473 kfree_skb(phy->pending_skb);
476 phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
477 if (phy->pending_skb == NULL) {
478 phy->hard_fault = -ENOMEM;
479 nfc_hci_recv_frame(phy->hdev, NULL);
485 static struct nfc_phy_ops i2c_phy_ops = {
486 .write = st21nfca_hci_i2c_write,
487 .enable = st21nfca_hci_i2c_enable,
488 .disable = st21nfca_hci_i2c_disable,
491 static const struct acpi_gpio_params enable_gpios = { 1, 0, false };
493 static const struct acpi_gpio_mapping acpi_st21nfca_gpios[] = {
494 { "enable-gpios", &enable_gpios, 1 },
498 static int st21nfca_hci_i2c_probe(struct i2c_client *client,
499 const struct i2c_device_id *id)
501 struct device *dev = &client->dev;
502 struct st21nfca_i2c_phy *phy;
505 dev_dbg(&client->dev, "%s\n", __func__);
506 dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
508 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
509 nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
513 phy = devm_kzalloc(&client->dev, sizeof(struct st21nfca_i2c_phy),
518 phy->i2c_dev = client;
519 phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);
520 if (phy->pending_skb == NULL)
523 phy->current_read_len = 0;
525 mutex_init(&phy->phy_lock);
526 i2c_set_clientdata(client, phy);
528 r = devm_acpi_dev_add_driver_gpios(dev, acpi_st21nfca_gpios);
530 dev_dbg(dev, "Unable to add GPIO mapping table\n");
532 /* Get EN GPIO from resource provider */
533 phy->gpiod_ena = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
534 if (IS_ERR(phy->gpiod_ena)) {
535 nfc_err(dev, "Unable to get ENABLE GPIO\n");
536 r = PTR_ERR(phy->gpiod_ena);
540 phy->se_status.is_ese_present =
541 device_property_read_bool(&client->dev, "ese-present");
542 phy->se_status.is_uicc_present =
543 device_property_read_bool(&client->dev, "uicc-present");
545 r = st21nfca_hci_platform_init(phy);
547 nfc_err(&client->dev, "Unable to reboot st21nfca\n");
551 r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
552 st21nfca_hci_irq_thread_fn,
554 ST21NFCA_HCI_DRIVER_NAME, phy);
556 nfc_err(&client->dev, "Unable to register IRQ handler\n");
560 r = st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
561 ST21NFCA_FRAME_HEADROOM,
562 ST21NFCA_FRAME_TAILROOM,
563 ST21NFCA_HCI_LLC_MAX_PAYLOAD,
572 kfree_skb(phy->pending_skb);
576 static int st21nfca_hci_i2c_remove(struct i2c_client *client)
578 struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);
580 dev_dbg(&client->dev, "%s\n", __func__);
582 st21nfca_hci_remove(phy->hdev);
585 st21nfca_hci_i2c_disable(phy);
586 if (phy->pending_skb)
587 kfree_skb(phy->pending_skb);
592 static const struct i2c_device_id st21nfca_hci_i2c_id_table[] = {
593 {ST21NFCA_HCI_DRIVER_NAME, 0},
596 MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table);
598 static const struct acpi_device_id st21nfca_hci_i2c_acpi_match[] = {
602 MODULE_DEVICE_TABLE(acpi, st21nfca_hci_i2c_acpi_match);
604 static const struct of_device_id of_st21nfca_i2c_match[] = {
605 { .compatible = "st,st21nfca-i2c", },
606 { .compatible = "st,st21nfca_i2c", },
609 MODULE_DEVICE_TABLE(of, of_st21nfca_i2c_match);
611 static struct i2c_driver st21nfca_hci_i2c_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),
617 .probe = st21nfca_hci_i2c_probe,
618 .id_table = st21nfca_hci_i2c_id_table,
619 .remove = st21nfca_hci_i2c_remove,
621 module_i2c_driver(st21nfca_hci_i2c_driver);
623 MODULE_LICENSE("GPL");
624 MODULE_DESCRIPTION(DRIVER_DESC);