1/*
2 * I2C Link Layer for ST21NFCB NCI 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/module.h>
21#include <linux/i2c.h>
22#include <linux/gpio.h>
23#include <linux/of_irq.h>
24#include <linux/of_gpio.h>
25#include <linux/interrupt.h>
26#include <linux/delay.h>
27#include <linux/nfc.h>
28#include <linux/platform_data/st21nfcb.h>
29
30#include "ndlc.h"
31
32#define DRIVER_DESC "NCI NFC driver for ST21NFCB"
33
34/* ndlc header */
35#define ST21NFCB_FRAME_HEADROOM	1
36#define ST21NFCB_FRAME_TAILROOM 0
37
38#define ST21NFCB_NCI_I2C_MIN_SIZE 4   /* PCB(1) + NCI Packet header(3) */
39#define ST21NFCB_NCI_I2C_MAX_SIZE 250 /* req 4.2.1 */
40
41#define ST21NFCB_NCI_I2C_DRIVER_NAME "st21nfcb_nci_i2c"
42
43static struct i2c_device_id st21nfcb_nci_i2c_id_table[] = {
44	{ST21NFCB_NCI_DRIVER_NAME, 0},
45	{}
46};
47MODULE_DEVICE_TABLE(i2c, st21nfcb_nci_i2c_id_table);
48
49struct st21nfcb_i2c_phy {
50	struct i2c_client *i2c_dev;
51	struct llt_ndlc *ndlc;
52
53	unsigned int gpio_irq;
54	unsigned int gpio_reset;
55	unsigned int irq_polarity;
56
57	int powered;
58};
59
60#define I2C_DUMP_SKB(info, skb)					\
61do {								\
62	pr_debug("%s:\n", info);				\
63	print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET,	\
64		       16, 1, (skb)->data, (skb)->len, 0);	\
65} while (0)
66
67static int st21nfcb_nci_i2c_enable(void *phy_id)
68{
69	struct st21nfcb_i2c_phy *phy = phy_id;
70
71	gpio_set_value(phy->gpio_reset, 0);
72	usleep_range(10000, 15000);
73	gpio_set_value(phy->gpio_reset, 1);
74	phy->powered = 1;
75	usleep_range(80000, 85000);
76
77	return 0;
78}
79
80static void st21nfcb_nci_i2c_disable(void *phy_id)
81{
82	struct st21nfcb_i2c_phy *phy = phy_id;
83
84	pr_info("\n");
85
86	phy->powered = 0;
87	/* reset chip in order to flush clf */
88	gpio_set_value(phy->gpio_reset, 0);
89	usleep_range(10000, 15000);
90	gpio_set_value(phy->gpio_reset, 1);
91}
92
93static void st21nfcb_nci_remove_header(struct sk_buff *skb)
94{
95	skb_pull(skb, ST21NFCB_FRAME_HEADROOM);
96}
97
98/*
99 * Writing a frame must not return the number of written bytes.
100 * It must return either zero for success, or <0 for error.
101 * In addition, it must not alter the skb
102 */
103static int st21nfcb_nci_i2c_write(void *phy_id, struct sk_buff *skb)
104{
105	int r = -1;
106	struct st21nfcb_i2c_phy *phy = phy_id;
107	struct i2c_client *client = phy->i2c_dev;
108
109	I2C_DUMP_SKB("st21nfcb_nci_i2c_write", skb);
110
111	if (phy->ndlc->hard_fault != 0)
112		return phy->ndlc->hard_fault;
113
114	r = i2c_master_send(client, skb->data, skb->len);
115	if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
116		usleep_range(1000, 4000);
117		r = i2c_master_send(client, skb->data, skb->len);
118	}
119
120	if (r >= 0) {
121		if (r != skb->len)
122			r = -EREMOTEIO;
123		else
124			r = 0;
125	}
126
127	st21nfcb_nci_remove_header(skb);
128
129	return r;
130}
131
132/*
133 * Reads an ndlc frame and returns it in a newly allocated sk_buff.
134 * returns:
135 * frame size : if received frame is complete (find ST21NFCB_SOF_EOF at
136 * end of read)
137 * -EAGAIN : if received frame is incomplete (not find ST21NFCB_SOF_EOF
138 * at end of read)
139 * -EREMOTEIO : i2c read error (fatal)
140 * -EBADMSG : frame was incorrect and discarded
141 * (value returned from st21nfcb_nci_i2c_repack)
142 * -EIO : if no ST21NFCB_SOF_EOF is found after reaching
143 * the read length end sequence
144 */
145static int st21nfcb_nci_i2c_read(struct st21nfcb_i2c_phy *phy,
146				 struct sk_buff **skb)
147{
148	int r;
149	u8 len;
150	u8 buf[ST21NFCB_NCI_I2C_MAX_SIZE];
151	struct i2c_client *client = phy->i2c_dev;
152
153	r = i2c_master_recv(client, buf, ST21NFCB_NCI_I2C_MIN_SIZE);
154	if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
155		usleep_range(1000, 4000);
156		r = i2c_master_recv(client, buf, ST21NFCB_NCI_I2C_MIN_SIZE);
157	}
158
159	if (r != ST21NFCB_NCI_I2C_MIN_SIZE)
160		return -EREMOTEIO;
161
162	len = be16_to_cpu(*(__be16 *) (buf + 2));
163	if (len > ST21NFCB_NCI_I2C_MAX_SIZE) {
164		nfc_err(&client->dev, "invalid frame len\n");
165		return -EBADMSG;
166	}
167
168	*skb = alloc_skb(ST21NFCB_NCI_I2C_MIN_SIZE + len, GFP_KERNEL);
169	if (*skb == NULL)
170		return -ENOMEM;
171
172	skb_reserve(*skb, ST21NFCB_NCI_I2C_MIN_SIZE);
173	skb_put(*skb, ST21NFCB_NCI_I2C_MIN_SIZE);
174	memcpy((*skb)->data, buf, ST21NFCB_NCI_I2C_MIN_SIZE);
175
176	if (!len)
177		return 0;
178
179	r = i2c_master_recv(client, buf, len);
180	if (r != len) {
181		kfree_skb(*skb);
182		return -EREMOTEIO;
183	}
184
185	skb_put(*skb, len);
186	memcpy((*skb)->data + ST21NFCB_NCI_I2C_MIN_SIZE, buf, len);
187
188	I2C_DUMP_SKB("i2c frame read", *skb);
189
190	return 0;
191}
192
193/*
194 * Reads an ndlc frame from the chip.
195 *
196 * On ST21NFCB, IRQ goes in idle state when read starts.
197 */
198static irqreturn_t st21nfcb_nci_irq_thread_fn(int irq, void *phy_id)
199{
200	struct st21nfcb_i2c_phy *phy = phy_id;
201	struct i2c_client *client;
202	struct sk_buff *skb = NULL;
203	int r;
204
205	if (!phy || irq != phy->i2c_dev->irq) {
206		WARN_ON_ONCE(1);
207		return IRQ_NONE;
208	}
209
210	client = phy->i2c_dev;
211	dev_dbg(&client->dev, "IRQ\n");
212
213	if (phy->ndlc->hard_fault)
214		return IRQ_HANDLED;
215
216	if (!phy->powered) {
217		st21nfcb_nci_i2c_disable(phy);
218		return IRQ_HANDLED;
219	}
220
221	r = st21nfcb_nci_i2c_read(phy, &skb);
222	if (r == -EREMOTEIO || r == -ENOMEM || r == -EBADMSG)
223		return IRQ_HANDLED;
224
225	ndlc_recv(phy->ndlc, skb);
226
227	return IRQ_HANDLED;
228}
229
230static struct nfc_phy_ops i2c_phy_ops = {
231	.write = st21nfcb_nci_i2c_write,
232	.enable = st21nfcb_nci_i2c_enable,
233	.disable = st21nfcb_nci_i2c_disable,
234};
235
236#ifdef CONFIG_OF
237static int st21nfcb_nci_i2c_of_request_resources(struct i2c_client *client)
238{
239	struct st21nfcb_i2c_phy *phy = i2c_get_clientdata(client);
240	struct device_node *pp;
241	int gpio;
242	int r;
243
244	pp = client->dev.of_node;
245	if (!pp)
246		return -ENODEV;
247
248	/* Get GPIO from device tree */
249	gpio = of_get_named_gpio(pp, "reset-gpios", 0);
250	if (gpio < 0) {
251		nfc_err(&client->dev,
252			"Failed to retrieve reset-gpios from device tree\n");
253		return gpio;
254	}
255
256	/* GPIO request and configuration */
257	r = devm_gpio_request_one(&client->dev, gpio,
258				GPIOF_OUT_INIT_HIGH, "clf_reset");
259	if (r) {
260		nfc_err(&client->dev, "Failed to request reset pin\n");
261		return -ENODEV;
262	}
263	phy->gpio_reset = gpio;
264
265	/* IRQ */
266	r = irq_of_parse_and_map(pp, 0);
267	if (r < 0) {
268		nfc_err(&client->dev, "Unable to get irq, error: %d\n", r);
269		return r;
270	}
271
272	phy->irq_polarity = irq_get_trigger_type(r);
273	client->irq = r;
274
275	return 0;
276}
277#else
278static int st21nfcb_nci_i2c_of_request_resources(struct i2c_client *client)
279{
280	return -ENODEV;
281}
282#endif
283
284static int st21nfcb_nci_i2c_request_resources(struct i2c_client *client)
285{
286	struct st21nfcb_nfc_platform_data *pdata;
287	struct st21nfcb_i2c_phy *phy = i2c_get_clientdata(client);
288	int r;
289	int irq;
290
291	pdata = client->dev.platform_data;
292	if (pdata == NULL) {
293		nfc_err(&client->dev, "No platform data\n");
294		return -EINVAL;
295	}
296
297	/* store for later use */
298	phy->gpio_irq = pdata->gpio_irq;
299	phy->gpio_reset = pdata->gpio_reset;
300	phy->irq_polarity = pdata->irq_polarity;
301
302	r = devm_gpio_request_one(&client->dev, phy->gpio_irq,
303				GPIOF_IN, "clf_irq");
304	if (r) {
305		pr_err("%s : gpio_request failed\n", __FILE__);
306		return -ENODEV;
307	}
308
309	r = devm_gpio_request_one(&client->dev,
310			phy->gpio_reset, GPIOF_OUT_INIT_HIGH, "clf_reset");
311	if (r) {
312		pr_err("%s : reset gpio_request failed\n", __FILE__);
313		return -ENODEV;
314	}
315
316	/* IRQ */
317	irq = gpio_to_irq(phy->gpio_irq);
318	if (irq < 0) {
319		nfc_err(&client->dev,
320			"Unable to get irq number for GPIO %d error %d\n",
321			phy->gpio_irq, r);
322		return -ENODEV;
323	}
324	client->irq = irq;
325
326	return 0;
327}
328
329static int st21nfcb_nci_i2c_probe(struct i2c_client *client,
330				  const struct i2c_device_id *id)
331{
332	struct st21nfcb_i2c_phy *phy;
333	struct st21nfcb_nfc_platform_data *pdata;
334	int r;
335
336	dev_dbg(&client->dev, "%s\n", __func__);
337	dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
338
339	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
340		nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");
341		return -ENODEV;
342	}
343
344	phy = devm_kzalloc(&client->dev, sizeof(struct st21nfcb_i2c_phy),
345			   GFP_KERNEL);
346	if (!phy) {
347		nfc_err(&client->dev,
348			"Cannot allocate memory for st21nfcb i2c phy.\n");
349		return -ENOMEM;
350	}
351
352	phy->i2c_dev = client;
353
354	i2c_set_clientdata(client, phy);
355
356	pdata = client->dev.platform_data;
357	if (!pdata && client->dev.of_node) {
358		r = st21nfcb_nci_i2c_of_request_resources(client);
359		if (r) {
360			nfc_err(&client->dev, "No platform data\n");
361			return r;
362		}
363	} else if (pdata) {
364		r = st21nfcb_nci_i2c_request_resources(client);
365		if (r) {
366			nfc_err(&client->dev,
367				"Cannot get platform resources\n");
368			return r;
369		}
370	} else {
371		nfc_err(&client->dev,
372			"st21nfcb platform resources not available\n");
373		return -ENODEV;
374	}
375
376	r = devm_request_threaded_irq(&client->dev, client->irq, NULL,
377				st21nfcb_nci_irq_thread_fn,
378				phy->irq_polarity | IRQF_ONESHOT,
379				ST21NFCB_NCI_DRIVER_NAME, phy);
380	if (r < 0) {
381		nfc_err(&client->dev, "Unable to register IRQ handler\n");
382		return r;
383	}
384
385	return ndlc_probe(phy, &i2c_phy_ops, &client->dev,
386			ST21NFCB_FRAME_HEADROOM, ST21NFCB_FRAME_TAILROOM,
387			&phy->ndlc);
388}
389
390static int st21nfcb_nci_i2c_remove(struct i2c_client *client)
391{
392	struct st21nfcb_i2c_phy *phy = i2c_get_clientdata(client);
393
394	dev_dbg(&client->dev, "%s\n", __func__);
395
396	ndlc_remove(phy->ndlc);
397
398	if (phy->powered)
399		st21nfcb_nci_i2c_disable(phy);
400
401	return 0;
402}
403
404static const struct of_device_id of_st21nfcb_i2c_match[] = {
405	{ .compatible = "st,st21nfcb_i2c", },
406	{}
407};
408
409static struct i2c_driver st21nfcb_nci_i2c_driver = {
410	.driver = {
411		.owner = THIS_MODULE,
412		.name = ST21NFCB_NCI_I2C_DRIVER_NAME,
413		.of_match_table = of_match_ptr(of_st21nfcb_i2c_match),
414	},
415	.probe = st21nfcb_nci_i2c_probe,
416	.id_table = st21nfcb_nci_i2c_id_table,
417	.remove = st21nfcb_nci_i2c_remove,
418};
419
420module_i2c_driver(st21nfcb_nci_i2c_driver);
421
422MODULE_LICENSE("GPL");
423MODULE_DESCRIPTION(DRIVER_DESC);
424