xref: /linux/drivers/nfc/pn544/i2c.c (revision d0b73b488c55df905ea8faaad079f8535629ed26) 
1 /*
2  * I2C Link Layer for PN544 HCI based Driver
3  *
4  * Copyright (C) 2012  Intel Corporation. All rights reserved.
5  *
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.
9  *
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.
14  *
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.
19  */
20 
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>
28 
29 #include <linux/platform_data/pn544.h>
30 
31 #include <net/nfc/hci.h>
32 #include <net/nfc/llc.h>
33 
34 #include "pn544.h"
35 
36 #define PN544_I2C_FRAME_HEADROOM 1
37 #define PN544_I2C_FRAME_TAILROOM 2
38 
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)
48 
49 static struct i2c_device_id pn544_hci_i2c_id_table[] = {
50 	{"pn544", 0},
51 	{}
52 };
53 
54 MODULE_DEVICE_TABLE(i2c, pn544_hci_i2c_id_table);
55 
56 #define PN544_HCI_I2C_DRIVER_NAME "pn544_hci_i2c"
57 
58 struct pn544_i2c_phy {
59 	struct i2c_client *i2c_dev;
60 	struct nfc_hci_dev *hdev;
61 
62 	unsigned int gpio_en;
63 	unsigned int gpio_irq;
64 	unsigned int gpio_fw;
65 	unsigned int en_polarity;
66 
67 	int powered;
68 
69 	int hard_fault;		/*
70 				 * < 0 if hardware error occured (e.g. i2c err)
71 				 * and prevents normal operation.
72 				 */
73 };
74 
75 #define I2C_DUMP_SKB(info, skb)					\
76 do {								\
77 	pr_debug("%s:\n", info);				\
78 	print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET,	\
79 		       16, 1, (skb)->data, (skb)->len, 0);	\
80 } while (0)
81 
82 static void pn544_hci_i2c_platform_init(struct pn544_i2c_phy *phy)
83 {
84 	int polarity, retry, ret;
85 	char rset_cmd[] = { 0x05, 0xF9, 0x04, 0x00, 0xC3, 0xE5 };
86 	int count = sizeof(rset_cmd);
87 
88 	pr_info(DRIVER_DESC ": %s\n", __func__);
89 	dev_info(&phy->i2c_dev->dev, "Detecting nfc_en polarity\n");
90 
91 	/* Disable fw download */
92 	gpio_set_value(phy->gpio_fw, 0);
93 
94 	for (polarity = 0; polarity < 2; polarity++) {
95 		phy->en_polarity = polarity;
96 		retry = 3;
97 		while (retry--) {
98 			/* power off */
99 			gpio_set_value(phy->gpio_en, !phy->en_polarity);
100 			usleep_range(10000, 15000);
101 
102 			/* power on */
103 			gpio_set_value(phy->gpio_en, phy->en_polarity);
104 			usleep_range(10000, 15000);
105 
106 			/* send reset */
107 			dev_dbg(&phy->i2c_dev->dev, "Sending reset cmd\n");
108 			ret = i2c_master_send(phy->i2c_dev, rset_cmd, count);
109 			if (ret == count) {
110 				dev_info(&phy->i2c_dev->dev,
111 					 "nfc_en polarity : active %s\n",
112 					 (polarity == 0 ? "low" : "high"));
113 				goto out;
114 			}
115 		}
116 	}
117 
118 	dev_err(&phy->i2c_dev->dev,
119 		"Could not detect nfc_en polarity, fallback to active high\n");
120 
121 out:
122 	gpio_set_value(phy->gpio_en, !phy->en_polarity);
123 }
124 
125 static int pn544_hci_i2c_enable(void *phy_id)
126 {
127 	struct pn544_i2c_phy *phy = phy_id;
128 
129 	pr_info(DRIVER_DESC ": %s\n", __func__);
130 
131 	gpio_set_value(phy->gpio_fw, 0);
132 	gpio_set_value(phy->gpio_en, phy->en_polarity);
133 	usleep_range(10000, 15000);
134 
135 	phy->powered = 1;
136 
137 	return 0;
138 }
139 
140 static void pn544_hci_i2c_disable(void *phy_id)
141 {
142 	struct pn544_i2c_phy *phy = phy_id;
143 
144 	pr_info(DRIVER_DESC ": %s\n", __func__);
145 
146 	gpio_set_value(phy->gpio_fw, 0);
147 	gpio_set_value(phy->gpio_en, !phy->en_polarity);
148 	usleep_range(10000, 15000);
149 
150 	gpio_set_value(phy->gpio_en, phy->en_polarity);
151 	usleep_range(10000, 15000);
152 
153 	gpio_set_value(phy->gpio_en, !phy->en_polarity);
154 	usleep_range(10000, 15000);
155 
156 	phy->powered = 0;
157 }
158 
159 static void pn544_hci_i2c_add_len_crc(struct sk_buff *skb)
160 {
161 	u16 crc;
162 	int len;
163 
164 	len = skb->len + 2;
165 	*skb_push(skb, 1) = len;
166 
167 	crc = crc_ccitt(0xffff, skb->data, skb->len);
168 	crc = ~crc;
169 	*skb_put(skb, 1) = crc & 0xff;
170 	*skb_put(skb, 1) = crc >> 8;
171 }
172 
173 static void pn544_hci_i2c_remove_len_crc(struct sk_buff *skb)
174 {
175 	skb_pull(skb, PN544_I2C_FRAME_HEADROOM);
176 	skb_trim(skb, PN544_I2C_FRAME_TAILROOM);
177 }
178 
179 /*
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
183  */
184 static int pn544_hci_i2c_write(void *phy_id, struct sk_buff *skb)
185 {
186 	int r;
187 	struct pn544_i2c_phy *phy = phy_id;
188 	struct i2c_client *client = phy->i2c_dev;
189 
190 	if (phy->hard_fault != 0)
191 		return phy->hard_fault;
192 
193 	usleep_range(3000, 6000);
194 
195 	pn544_hci_i2c_add_len_crc(skb);
196 
197 	I2C_DUMP_SKB("i2c frame written", skb);
198 
199 	r = i2c_master_send(client, skb->data, skb->len);
200 
201 	if (r == -EREMOTEIO) {	/* Retry, chip was in standby */
202 		usleep_range(6000, 10000);
203 		r = i2c_master_send(client, skb->data, skb->len);
204 	}
205 
206 	if (r >= 0) {
207 		if (r != skb->len)
208 			r = -EREMOTEIO;
209 		else
210 			r = 0;
211 	}
212 
213 	pn544_hci_i2c_remove_len_crc(skb);
214 
215 	return r;
216 }
217 
218 static int check_crc(u8 *buf, int buflen)
219 {
220 	int len;
221 	u16 crc;
222 
223 	len = buf[0] + 1;
224 	crc = crc_ccitt(0xffff, buf, len - 2);
225 	crc = ~crc;
226 
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]);
231 
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);
235 		return -EPERM;
236 	}
237 	return 0;
238 }
239 
240 /*
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.
244  * returns:
245  * -EREMOTEIO : i2c read error (fatal)
246  * -EBADMSG : frame was incorrect and discarded
247  * -ENOMEM : cannot allocate skb, frame dropped
248  */
249 static int pn544_hci_i2c_read(struct pn544_i2c_phy *phy, struct sk_buff **skb)
250 {
251 	int r;
252 	u8 len;
253 	u8 tmp[PN544_HCI_I2C_LLC_MAX_SIZE - 1];
254 	struct i2c_client *client = phy->i2c_dev;
255 
256 	r = i2c_master_recv(client, &len, 1);
257 	if (r != 1) {
258 		dev_err(&client->dev, "cannot read len byte\n");
259 		return -EREMOTEIO;
260 	}
261 
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");
265 		r = -EBADMSG;
266 		goto flush;
267 	}
268 
269 	*skb = alloc_skb(1 + len, GFP_KERNEL);
270 	if (*skb == NULL) {
271 		r = -ENOMEM;
272 		goto flush;
273 	}
274 
275 	*skb_put(*skb, 1) = len;
276 
277 	r = i2c_master_recv(client, skb_put(*skb, len), len);
278 	if (r != len) {
279 		kfree_skb(*skb);
280 		return -EREMOTEIO;
281 	}
282 
283 	I2C_DUMP_SKB("i2c frame read", *skb);
284 
285 	r = check_crc((*skb)->data, (*skb)->len);
286 	if (r != 0) {
287 		kfree_skb(*skb);
288 		r = -EBADMSG;
289 		goto flush;
290 	}
291 
292 	skb_pull(*skb, 1);
293 	skb_trim(*skb, (*skb)->len - 2);
294 
295 	usleep_range(3000, 6000);
296 
297 	return 0;
298 
299 flush:
300 	if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
301 		r = -EREMOTEIO;
302 
303 	usleep_range(3000, 6000);
304 
305 	return r;
306 }
307 
308 /*
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.
323  */
324 static irqreturn_t pn544_hci_i2c_irq_thread_fn(int irq, void *phy_id)
325 {
326 	struct pn544_i2c_phy *phy = phy_id;
327 	struct i2c_client *client;
328 	struct sk_buff *skb = NULL;
329 	int r;
330 
331 	if (!phy || irq != phy->i2c_dev->irq) {
332 		WARN_ON_ONCE(1);
333 		return IRQ_NONE;
334 	}
335 
336 	client = phy->i2c_dev;
337 	dev_dbg(&client->dev, "IRQ\n");
338 
339 	if (phy->hard_fault != 0)
340 		return IRQ_HANDLED;
341 
342 	r = pn544_hci_i2c_read(phy, &skb);
343 	if (r == -EREMOTEIO) {
344 		phy->hard_fault = r;
345 
346 		nfc_hci_recv_frame(phy->hdev, NULL);
347 
348 		return IRQ_HANDLED;
349 	} else if ((r == -ENOMEM) || (r == -EBADMSG)) {
350 		return IRQ_HANDLED;
351 	}
352 
353 	nfc_hci_recv_frame(phy->hdev, skb);
354 
355 	return IRQ_HANDLED;
356 }
357 
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,
362 };
363 
364 static int pn544_hci_i2c_probe(struct i2c_client *client,
365 			       const struct i2c_device_id *id)
366 {
367 	struct pn544_i2c_phy *phy;
368 	struct pn544_nfc_platform_data *pdata;
369 	int r = 0;
370 
371 	dev_dbg(&client->dev, "%s\n", __func__);
372 	dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
373 
374 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
375 		dev_err(&client->dev, "Need I2C_FUNC_I2C\n");
376 		return -ENODEV;
377 	}
378 
379 	phy = kzalloc(sizeof(struct pn544_i2c_phy), GFP_KERNEL);
380 	if (!phy) {
381 		dev_err(&client->dev,
382 			"Cannot allocate memory for pn544 i2c phy.\n");
383 		r = -ENOMEM;
384 		goto err_phy_alloc;
385 	}
386 
387 	phy->i2c_dev = client;
388 	i2c_set_clientdata(client, phy);
389 
390 	pdata = client->dev.platform_data;
391 	if (pdata == NULL) {
392 		dev_err(&client->dev, "No platform data\n");
393 		r = -EINVAL;
394 		goto err_pdata;
395 	}
396 
397 	if (pdata->request_resources == NULL) {
398 		dev_err(&client->dev, "request_resources() missing\n");
399 		r = -EINVAL;
400 		goto err_pdata;
401 	}
402 
403 	r = pdata->request_resources(client);
404 	if (r) {
405 		dev_err(&client->dev, "Cannot get platform resources\n");
406 		goto err_pdata;
407 	}
408 
409 	phy->gpio_en = pdata->get_gpio(NFC_GPIO_ENABLE);
410 	phy->gpio_fw = pdata->get_gpio(NFC_GPIO_FW_RESET);
411 	phy->gpio_irq = pdata->get_gpio(NFC_GPIO_IRQ);
412 
413 	pn544_hci_i2c_platform_init(phy);
414 
415 	r = request_threaded_irq(client->irq, NULL, pn544_hci_i2c_irq_thread_fn,
416 				 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
417 				 PN544_HCI_I2C_DRIVER_NAME, phy);
418 	if (r < 0) {
419 		dev_err(&client->dev, "Unable to register IRQ handler\n");
420 		goto err_rti;
421 	}
422 
423 	r = pn544_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
424 			    PN544_I2C_FRAME_HEADROOM, PN544_I2C_FRAME_TAILROOM,
425 			    PN544_HCI_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
426 	if (r < 0)
427 		goto err_hci;
428 
429 	return 0;
430 
431 err_hci:
432 	free_irq(client->irq, phy);
433 
434 err_rti:
435 	if (pdata->free_resources != NULL)
436 		pdata->free_resources();
437 
438 err_pdata:
439 	kfree(phy);
440 
441 err_phy_alloc:
442 	return r;
443 }
444 
445 static int pn544_hci_i2c_remove(struct i2c_client *client)
446 {
447 	struct pn544_i2c_phy *phy = i2c_get_clientdata(client);
448 	struct pn544_nfc_platform_data *pdata = client->dev.platform_data;
449 
450 	dev_dbg(&client->dev, "%s\n", __func__);
451 
452 	pn544_hci_remove(phy->hdev);
453 
454 	if (phy->powered)
455 		pn544_hci_i2c_disable(phy);
456 
457 	free_irq(client->irq, phy);
458 	if (pdata->free_resources)
459 		pdata->free_resources();
460 
461 	kfree(phy);
462 
463 	return 0;
464 }
465 
466 static struct i2c_driver pn544_hci_i2c_driver = {
467 	.driver = {
468 		   .name = PN544_HCI_I2C_DRIVER_NAME,
469 		  },
470 	.probe = pn544_hci_i2c_probe,
471 	.id_table = pn544_hci_i2c_id_table,
472 	.remove = pn544_hci_i2c_remove,
473 };
474 
475 static int __init pn544_hci_i2c_init(void)
476 {
477 	int r;
478 
479 	pr_debug(DRIVER_DESC ": %s\n", __func__);
480 
481 	r = i2c_add_driver(&pn544_hci_i2c_driver);
482 	if (r) {
483 		pr_err(PN544_HCI_I2C_DRIVER_NAME
484 		       ": driver registration failed\n");
485 		return r;
486 	}
487 
488 	return 0;
489 }
490 
491 static void __exit pn544_hci_i2c_exit(void)
492 {
493 	i2c_del_driver(&pn544_hci_i2c_driver);
494 }
495 
496 module_init(pn544_hci_i2c_init);
497 module_exit(pn544_hci_i2c_exit);
498 
499 MODULE_LICENSE("GPL");
500 MODULE_DESCRIPTION(DRIVER_DESC);
501