summaryrefslogtreecommitdiff
path: root/drivers/nfc/microread/i2c.c
blob: 661e2c8143c40a8e4ab6e98b76a007eafa9a6fd4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
/*
 * HCI based Driver for Inside Secure microread NFC Chip - i2c layer
 *
 * Copyright (C) 2013 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/gpio.h>

#include <linux/nfc.h>
#include <net/nfc/hci.h>
#include <net/nfc/llc.h>

#include "microread.h"

#define MICROREAD_I2C_DRIVER_NAME "microread"

#define MICROREAD_I2C_FRAME_HEADROOM 1
#define MICROREAD_I2C_FRAME_TAILROOM 1

/* framing in HCI mode */
#define MICROREAD_I2C_LLC_LEN		1
#define MICROREAD_I2C_LLC_CRC		1
#define MICROREAD_I2C_LLC_LEN_CRC	(MICROREAD_I2C_LLC_LEN + \
					MICROREAD_I2C_LLC_CRC)
#define MICROREAD_I2C_LLC_MIN_SIZE	(1 + MICROREAD_I2C_LLC_LEN_CRC)
#define MICROREAD_I2C_LLC_MAX_PAYLOAD	29
#define MICROREAD_I2C_LLC_MAX_SIZE	(MICROREAD_I2C_LLC_LEN_CRC + 1 + \
					MICROREAD_I2C_LLC_MAX_PAYLOAD)

struct microread_i2c_phy {
	struct i2c_client *i2c_dev;
	struct nfc_hci_dev *hdev;

	int irq;

	int hard_fault;		/*
				 * < 0 if hardware error occured (e.g. i2c err)
				 * and prevents normal operation.
				 */
};

#define I2C_DUMP_SKB(info, skb)					\
do {								\
	pr_debug("%s:\n", info);				\
	print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET,	\
		       16, 1, (skb)->data, (skb)->len, 0);	\
} while (0)

static void microread_i2c_add_len_crc(struct sk_buff *skb)
{
	int i;
	u8 crc = 0;
	int len;

	len = skb->len;
	*skb_push(skb, 1) = len;

	for (i = 0; i < skb->len; i++)
		crc = crc ^ skb->data[i];

	*skb_put(skb, 1) = crc;
}

static void microread_i2c_remove_len_crc(struct sk_buff *skb)
{
	skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM);
	skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM);
}

static int check_crc(struct sk_buff *skb)
{
	int i;
	u8 crc = 0;

	for (i = 0; i < skb->len - 1; i++)
		crc = crc ^ skb->data[i];

	if (crc != skb->data[skb->len-1]) {
		pr_err("CRC error 0x%x != 0x%x\n", crc, skb->data[skb->len-1]);
		pr_info("%s: BAD CRC\n", __func__);
		return -EPERM;
	}

	return 0;
}

static int microread_i2c_enable(void *phy_id)
{
	return 0;
}

static void microread_i2c_disable(void *phy_id)
{
	return;
}

static int microread_i2c_write(void *phy_id, struct sk_buff *skb)
{
	int r;
	struct microread_i2c_phy *phy = phy_id;
	struct i2c_client *client = phy->i2c_dev;

	if (phy->hard_fault != 0)
		return phy->hard_fault;

	usleep_range(3000, 6000);

	microread_i2c_add_len_crc(skb);

	I2C_DUMP_SKB("i2c frame written", skb);

	r = i2c_master_send(client, skb->data, skb->len);

	if (r == -EREMOTEIO) {	/* Retry, chip was in standby */
		usleep_range(6000, 10000);
		r = i2c_master_send(client, skb->data, skb->len);
	}

	if (r >= 0) {
		if (r != skb->len)
			r = -EREMOTEIO;
		else
			r = 0;
	}

	microread_i2c_remove_len_crc(skb);

	return r;
}


static int microread_i2c_read(struct microread_i2c_phy *phy,
			      struct sk_buff **skb)
{
	int r;
	u8 len;
	u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1];
	struct i2c_client *client = phy->i2c_dev;

	r = i2c_master_recv(client, &len, 1);
	if (r != 1) {
		nfc_err(&client->dev, "cannot read len byte\n");
		return -EREMOTEIO;
	}

	if ((len < MICROREAD_I2C_LLC_MIN_SIZE) ||
	    (len > MICROREAD_I2C_LLC_MAX_SIZE)) {
		nfc_err(&client->dev, "invalid len byte\n");
		r = -EBADMSG;
		goto flush;
	}

	*skb = alloc_skb(1 + len, GFP_KERNEL);
	if (*skb == NULL) {
		r = -ENOMEM;
		goto flush;
	}

	*skb_put(*skb, 1) = len;

	r = i2c_master_recv(client, skb_put(*skb, len), len);
	if (r != len) {
		kfree_skb(*skb);
		return -EREMOTEIO;
	}

	I2C_DUMP_SKB("cc frame read", *skb);

	r = check_crc(*skb);
	if (r != 0) {
		kfree_skb(*skb);
		r = -EBADMSG;
		goto flush;
	}

	skb_pull(*skb, 1);
	skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM);

	usleep_range(3000, 6000);

	return 0;

flush:
	if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
		r = -EREMOTEIO;

	usleep_range(3000, 6000);

	return r;
}

static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id)
{
	struct microread_i2c_phy *phy = phy_id;
	struct i2c_client *client;
	struct sk_buff *skb = NULL;
	int r;

	if (!phy || irq != phy->i2c_dev->irq) {
		WARN_ON_ONCE(1);
		return IRQ_NONE;
	}

	client = phy->i2c_dev;

	if (phy->hard_fault != 0)
		return IRQ_HANDLED;

	r = microread_i2c_read(phy, &skb);
	if (r == -EREMOTEIO) {
		phy->hard_fault = r;

		nfc_hci_recv_frame(phy->hdev, NULL);

		return IRQ_HANDLED;
	} else if ((r == -ENOMEM) || (r == -EBADMSG)) {
		return IRQ_HANDLED;
	}

	nfc_hci_recv_frame(phy->hdev, skb);

	return IRQ_HANDLED;
}

static struct nfc_phy_ops i2c_phy_ops = {
	.write = microread_i2c_write,
	.enable = microread_i2c_enable,
	.disable = microread_i2c_disable,
};

static int microread_i2c_probe(struct i2c_client *client,
			       const struct i2c_device_id *id)
{
	struct microread_i2c_phy *phy;
	struct microread_nfc_platform_data *pdata =
		dev_get_platdata(&client->dev);
	int r;

	dev_dbg(&client->dev, "client %p\n", client);

	if (!pdata) {
		nfc_err(&client->dev, "client %p: missing platform data\n",
			client);
		return -EINVAL;
	}

	phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy),
			   GFP_KERNEL);
	if (!phy)
		return -ENOMEM;

	i2c_set_clientdata(client, phy);
	phy->i2c_dev = client;

	r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn,
				 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
				 MICROREAD_I2C_DRIVER_NAME, phy);
	if (r) {
		nfc_err(&client->dev, "Unable to register IRQ handler\n");
		return r;
	}

	r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
			    MICROREAD_I2C_FRAME_HEADROOM,
			    MICROREAD_I2C_FRAME_TAILROOM,
			    MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
	if (r < 0)
		goto err_irq;

	nfc_info(&client->dev, "Probed\n");

	return 0;

err_irq:
	free_irq(client->irq, phy);

	return r;
}

static int microread_i2c_remove(struct i2c_client *client)
{
	struct microread_i2c_phy *phy = i2c_get_clientdata(client);

	microread_remove(phy->hdev);

	free_irq(client->irq, phy);

	return 0;
}

static struct i2c_device_id microread_i2c_id[] = {
	{ MICROREAD_I2C_DRIVER_NAME, 0},
	{ }
};
MODULE_DEVICE_TABLE(i2c, microread_i2c_id);

static struct i2c_driver microread_i2c_driver = {
	.driver = {
		.name = MICROREAD_I2C_DRIVER_NAME,
	},
	.probe		= microread_i2c_probe,
	.remove		= microread_i2c_remove,
	.id_table	= microread_i2c_id,
};

module_i2c_driver(microread_i2c_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION(DRIVER_DESC);