2 * I2C Link Layer for PN544 HCI based Driver
4 * Copyright (C) 2012 Intel Corporation. All rights reserved.
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms and conditions of the GNU General Public License,
8 * version 2, as published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the
17 * Free Software Foundation, Inc.,
18 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
21 #include <linux/crc-ccitt.h>
22 #include <linux/module.h>
23 #include <linux/i2c.h>
24 #include <linux/gpio.h>
25 #include <linux/miscdevice.h>
26 #include <linux/interrupt.h>
27 #include <linux/delay.h>
29 #include <linux/platform_data/pn544.h>
31 #include <net/nfc/hci.h>
32 #include <net/nfc/llc.h>
36 #define PN544_I2C_FRAME_HEADROOM 1
37 #define PN544_I2C_FRAME_TAILROOM 2
39 /* framing in HCI mode */
40 #define PN544_HCI_I2C_LLC_LEN 1
41 #define PN544_HCI_I2C_LLC_CRC 2
42 #define PN544_HCI_I2C_LLC_LEN_CRC (PN544_HCI_I2C_LLC_LEN + \
43 PN544_HCI_I2C_LLC_CRC)
44 #define PN544_HCI_I2C_LLC_MIN_SIZE (1 + PN544_HCI_I2C_LLC_LEN_CRC)
45 #define PN544_HCI_I2C_LLC_MAX_PAYLOAD 29
46 #define PN544_HCI_I2C_LLC_MAX_SIZE (PN544_HCI_I2C_LLC_LEN_CRC + 1 + \
47 PN544_HCI_I2C_LLC_MAX_PAYLOAD)
49 static struct i2c_device_id pn544_hci_i2c_id_table[] = {
54 MODULE_DEVICE_TABLE(i2c, pn544_hci_i2c_id_table);
56 #define PN544_HCI_I2C_DRIVER_NAME "pn544_hci_i2c"
58 struct pn544_i2c_phy {
59 struct i2c_client *i2c_dev;
60 struct nfc_hci_dev *hdev;
63 unsigned int gpio_irq;
65 unsigned int en_polarity;
70 * < 0 if hardware error occured (e.g. i2c err)
71 * and prevents normal operation.
75 #define I2C_DUMP_SKB(info, skb) \
77 pr_debug("%s:\n", info); \
78 print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
79 16, 1, (skb)->data, (skb)->len, 0); \
82 static void pn544_hci_i2c_platform_init(struct pn544_i2c_phy *phy)
84 int polarity, retry, ret;
85 char rset_cmd[] = { 0x05, 0xF9, 0x04, 0x00, 0xC3, 0xE5 };
86 int count = sizeof(rset_cmd);
88 pr_info(DRIVER_DESC ": %s\n", __func__);
89 dev_info(&phy->i2c_dev->dev, "Detecting nfc_en polarity\n");
91 /* Disable fw download */
92 gpio_set_value(phy->gpio_fw, 0);
94 for (polarity = 0; polarity < 2; polarity++) {
95 phy->en_polarity = polarity;
99 gpio_set_value(phy->gpio_en, !phy->en_polarity);
100 usleep_range(10000, 15000);
103 gpio_set_value(phy->gpio_en, phy->en_polarity);
104 usleep_range(10000, 15000);
107 dev_dbg(&phy->i2c_dev->dev, "Sending reset cmd\n");
108 ret = i2c_master_send(phy->i2c_dev, rset_cmd, count);
110 dev_info(&phy->i2c_dev->dev,
111 "nfc_en polarity : active %s\n",
112 (polarity == 0 ? "low" : "high"));
118 dev_err(&phy->i2c_dev->dev,
119 "Could not detect nfc_en polarity, fallback to active high\n");
122 gpio_set_value(phy->gpio_en, !phy->en_polarity);
125 static int pn544_hci_i2c_enable(void *phy_id)
127 struct pn544_i2c_phy *phy = phy_id;
129 pr_info(DRIVER_DESC ": %s\n", __func__);
131 gpio_set_value(phy->gpio_fw, 0);
132 gpio_set_value(phy->gpio_en, phy->en_polarity);
133 usleep_range(10000, 15000);
140 static void pn544_hci_i2c_disable(void *phy_id)
142 struct pn544_i2c_phy *phy = phy_id;
144 pr_info(DRIVER_DESC ": %s\n", __func__);
146 gpio_set_value(phy->gpio_fw, 0);
147 gpio_set_value(phy->gpio_en, !phy->en_polarity);
148 usleep_range(10000, 15000);
150 gpio_set_value(phy->gpio_en, phy->en_polarity);
151 usleep_range(10000, 15000);
153 gpio_set_value(phy->gpio_en, !phy->en_polarity);
154 usleep_range(10000, 15000);
159 static void pn544_hci_i2c_add_len_crc(struct sk_buff *skb)
165 *skb_push(skb, 1) = len;
167 crc = crc_ccitt(0xffff, skb->data, skb->len);
169 *skb_put(skb, 1) = crc & 0xff;
170 *skb_put(skb, 1) = crc >> 8;
173 static void pn544_hci_i2c_remove_len_crc(struct sk_buff *skb)
175 skb_pull(skb, PN544_I2C_FRAME_HEADROOM);
176 skb_trim(skb, PN544_I2C_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 pn544_hci_i2c_write(void *phy_id, struct sk_buff *skb)
187 struct pn544_i2c_phy *phy = phy_id;
188 struct i2c_client *client = phy->i2c_dev;
190 if (phy->hard_fault != 0)
191 return phy->hard_fault;
193 usleep_range(3000, 6000);
195 pn544_hci_i2c_add_len_crc(skb);
197 I2C_DUMP_SKB("i2c frame written", skb);
199 r = i2c_master_send(client, skb->data, skb->len);
201 if (r == -EREMOTEIO) { /* Retry, chip was in standby */
202 usleep_range(6000, 10000);
203 r = i2c_master_send(client, skb->data, skb->len);
213 pn544_hci_i2c_remove_len_crc(skb);
218 static int check_crc(u8 *buf, int buflen)
224 crc = crc_ccitt(0xffff, buf, len - 2);
227 if (buf[len - 2] != (crc & 0xff) || buf[len - 1] != (crc >> 8)) {
228 pr_err(PN544_HCI_I2C_DRIVER_NAME
229 ": CRC error 0x%x != 0x%x 0x%x\n",
230 crc, buf[len - 1], buf[len - 2]);
232 pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
233 print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
234 16, 2, buf, buflen, false);
241 * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees
242 * that i2c bus will be flushed and that next read will start on a new frame.
243 * returned skb contains only LLC header and payload.
245 * -EREMOTEIO : i2c read error (fatal)
246 * -EBADMSG : frame was incorrect and discarded
247 * -ENOMEM : cannot allocate skb, frame dropped
249 static int pn544_hci_i2c_read(struct pn544_i2c_phy *phy, struct sk_buff **skb)
253 u8 tmp[PN544_HCI_I2C_LLC_MAX_SIZE - 1];
254 struct i2c_client *client = phy->i2c_dev;
256 r = i2c_master_recv(client, &len, 1);
258 dev_err(&client->dev, "cannot read len byte\n");
262 if ((len < (PN544_HCI_I2C_LLC_MIN_SIZE - 1)) ||
263 (len > (PN544_HCI_I2C_LLC_MAX_SIZE - 1))) {
264 dev_err(&client->dev, "invalid len byte\n");
269 *skb = alloc_skb(1 + len, GFP_KERNEL);
275 *skb_put(*skb, 1) = len;
277 r = i2c_master_recv(client, skb_put(*skb, len), len);
283 I2C_DUMP_SKB("i2c frame read", *skb);
285 r = check_crc((*skb)->data, (*skb)->len);
293 skb_trim(*skb, (*skb)->len - 2);
295 usleep_range(3000, 6000);
300 if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
303 usleep_range(3000, 6000);
309 * Reads an shdlc frame from the chip. This is not as straightforward as it
310 * seems. There are cases where we could loose the frame start synchronization.
311 * The frame format is len-data-crc, and corruption can occur anywhere while
312 * transiting on i2c bus, such that we could read an invalid len.
313 * In order to recover synchronization with the next frame, we must be sure
314 * to read the real amount of data without using the len byte. We do this by
315 * assuming the following:
316 * - the chip will always present only one single complete frame on the bus
317 * before triggering the interrupt
318 * - the chip will not present a new frame until we have completely read
319 * the previous one (or until we have handled the interrupt).
320 * The tricky case is when we read a corrupted len that is less than the real
321 * len. We must detect this here in order to determine that we need to flush
322 * the bus. This is the reason why we check the crc here.
324 static irqreturn_t pn544_hci_i2c_irq_thread_fn(int irq, void *phy_id)
326 struct pn544_i2c_phy *phy = phy_id;
327 struct i2c_client *client;
328 struct sk_buff *skb = NULL;
331 if (!phy || irq != phy->i2c_dev->irq) {
336 client = phy->i2c_dev;
337 dev_dbg(&client->dev, "IRQ\n");
339 if (phy->hard_fault != 0)
342 r = pn544_hci_i2c_read(phy, &skb);
343 if (r == -EREMOTEIO) {
346 nfc_hci_recv_frame(phy->hdev, NULL);
349 } else if ((r == -ENOMEM) || (r == -EBADMSG)) {
353 nfc_hci_recv_frame(phy->hdev, skb);
358 static struct nfc_phy_ops i2c_phy_ops = {
359 .write = pn544_hci_i2c_write,
360 .enable = pn544_hci_i2c_enable,
361 .disable = pn544_hci_i2c_disable,
364 static int pn544_hci_i2c_probe(struct i2c_client *client,
365 const struct i2c_device_id *id)
367 struct pn544_i2c_phy *phy;
368 struct pn544_nfc_platform_data *pdata;
371 dev_dbg(&client->dev, "%s\n", __func__);
372 dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
374 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
375 dev_err(&client->dev, "Need I2C_FUNC_I2C\n");
379 phy = devm_kzalloc(&client->dev, sizeof(struct pn544_i2c_phy),
382 dev_err(&client->dev,
383 "Cannot allocate memory for pn544 i2c phy.\n");
387 phy->i2c_dev = client;
388 i2c_set_clientdata(client, phy);
390 pdata = client->dev.platform_data;
392 dev_err(&client->dev, "No platform data\n");
396 if (pdata->request_resources == NULL) {
397 dev_err(&client->dev, "request_resources() missing\n");
401 r = pdata->request_resources(client);
403 dev_err(&client->dev, "Cannot get platform resources\n");
407 phy->gpio_en = pdata->get_gpio(NFC_GPIO_ENABLE);
408 phy->gpio_fw = pdata->get_gpio(NFC_GPIO_FW_RESET);
409 phy->gpio_irq = pdata->get_gpio(NFC_GPIO_IRQ);
411 pn544_hci_i2c_platform_init(phy);
413 r = request_threaded_irq(client->irq, NULL, pn544_hci_i2c_irq_thread_fn,
414 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
415 PN544_HCI_I2C_DRIVER_NAME, phy);
417 dev_err(&client->dev, "Unable to register IRQ handler\n");
421 r = pn544_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
422 PN544_I2C_FRAME_HEADROOM, PN544_I2C_FRAME_TAILROOM,
423 PN544_HCI_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
430 free_irq(client->irq, phy);
433 if (pdata->free_resources != NULL)
434 pdata->free_resources();
439 static int pn544_hci_i2c_remove(struct i2c_client *client)
441 struct pn544_i2c_phy *phy = i2c_get_clientdata(client);
442 struct pn544_nfc_platform_data *pdata = client->dev.platform_data;
444 dev_dbg(&client->dev, "%s\n", __func__);
446 pn544_hci_remove(phy->hdev);
449 pn544_hci_i2c_disable(phy);
451 free_irq(client->irq, phy);
452 if (pdata->free_resources)
453 pdata->free_resources();
458 static struct i2c_driver pn544_hci_i2c_driver = {
460 .name = PN544_HCI_I2C_DRIVER_NAME,
462 .probe = pn544_hci_i2c_probe,
463 .id_table = pn544_hci_i2c_id_table,
464 .remove = pn544_hci_i2c_remove,
467 module_i2c_driver(pn544_hci_i2c_driver);
469 MODULE_LICENSE("GPL");
470 MODULE_DESCRIPTION(DRIVER_DESC);