summaryrefslogtreecommitdiffstats
path: root/drivers/nfc/pn533/uart.c
blob: 2eb5978bd79e1b5114bb34bab409fbeaae00faf8 (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
329
330
331
// SPDX-License-Identifier: GPL-2.0+
/*
 * Driver for NXP PN532 NFC Chip - UART transport layer
 *
 * Copyright (C) 2018 Lemonage Software GmbH
 * Author: Lars Pöschel <poeschel@lemonage.de>
 * All rights reserved.
 */

#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/nfc.h>
#include <linux/netdevice.h>
#include <linux/of.h>
#include <linux/serdev.h>
#include "pn533.h"

#define PN532_UART_SKB_BUFF_LEN	(PN533_CMD_DATAEXCH_DATA_MAXLEN * 2)

enum send_wakeup {
	PN532_SEND_NO_WAKEUP = 0,
	PN532_SEND_WAKEUP,
	PN532_SEND_LAST_WAKEUP,
};


struct pn532_uart_phy {
	struct serdev_device *serdev;
	struct sk_buff *recv_skb;
	struct pn533 *priv;
	/*
	 * send_wakeup variable is used to control if we need to send a wakeup
	 * request to the pn532 chip prior to our actual command. There is a
	 * little propability of a race condition. We decided to not mutex the
	 * variable as the worst that could happen is, that we send a wakeup
	 * to the chip that is already awake. This does not hurt. It is a
	 * no-op to the chip.
	 */
	enum send_wakeup send_wakeup;
	struct timer_list cmd_timeout;
	struct sk_buff *cur_out_buf;
};

static int pn532_uart_send_frame(struct pn533 *dev,
				struct sk_buff *out)
{
	/* wakeup sequence and dummy bytes for waiting time */
	static const u8 wakeup[] = {
		0x55, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
	struct pn532_uart_phy *pn532 = dev->phy;
	int err;

	print_hex_dump_debug("PN532_uart TX: ", DUMP_PREFIX_NONE, 16, 1,
			     out->data, out->len, false);

	pn532->cur_out_buf = out;
	if (pn532->send_wakeup) {
		err = serdev_device_write(pn532->serdev,
				wakeup, sizeof(wakeup),
				MAX_SCHEDULE_TIMEOUT);
		if (err < 0)
			return err;
	}

	if (pn532->send_wakeup == PN532_SEND_LAST_WAKEUP)
		pn532->send_wakeup = PN532_SEND_NO_WAKEUP;

	err = serdev_device_write(pn532->serdev, out->data, out->len,
			MAX_SCHEDULE_TIMEOUT);
	if (err < 0)
		return err;

	mod_timer(&pn532->cmd_timeout, HZ / 40 + jiffies);
	return 0;
}

static int pn532_uart_send_ack(struct pn533 *dev, gfp_t flags)
{
	/* spec 7.1.1.3:  Preamble, SoPC (2), ACK Code (2), Postamble */
	static const u8 ack[PN533_STD_FRAME_ACK_SIZE] = {
			0x00, 0x00, 0xff, 0x00, 0xff, 0x00};
	struct pn532_uart_phy *pn532 = dev->phy;
	int err;

	err = serdev_device_write(pn532->serdev, ack, sizeof(ack),
			MAX_SCHEDULE_TIMEOUT);
	if (err < 0)
		return err;

	return 0;
}

static void pn532_uart_abort_cmd(struct pn533 *dev, gfp_t flags)
{
	/* An ack will cancel the last issued command */
	pn532_uart_send_ack(dev, flags);
	/* schedule cmd_complete_work to finish current command execution */
	pn533_recv_frame(dev, NULL, -ENOENT);
}

static int pn532_dev_up(struct pn533 *dev)
{
	struct pn532_uart_phy *pn532 = dev->phy;
	int ret = 0;

	ret = serdev_device_open(pn532->serdev);
	if (ret)
		return ret;

	pn532->send_wakeup = PN532_SEND_LAST_WAKEUP;
	return ret;
}

static int pn532_dev_down(struct pn533 *dev)
{
	struct pn532_uart_phy *pn532 = dev->phy;

	serdev_device_close(pn532->serdev);
	pn532->send_wakeup = PN532_SEND_WAKEUP;

	return 0;
}

static const struct pn533_phy_ops uart_phy_ops = {
	.send_frame = pn532_uart_send_frame,
	.send_ack = pn532_uart_send_ack,
	.abort_cmd = pn532_uart_abort_cmd,
	.dev_up = pn532_dev_up,
	.dev_down = pn532_dev_down,
};

static void pn532_cmd_timeout(struct timer_list *t)
{
	struct pn532_uart_phy *dev = from_timer(dev, t, cmd_timeout);

	pn532_uart_send_frame(dev->priv, dev->cur_out_buf);
}

/*
 * scans the buffer if it contains a pn532 frame. It is not checked if the
 * frame is really valid. This is later done with pn533_rx_frame_is_valid.
 * This is useful for malformed or errornous transmitted frames. Adjusts the
 * bufferposition where the frame starts, since pn533_recv_frame expects a
 * well formed frame.
 */
static int pn532_uart_rx_is_frame(struct sk_buff *skb)
{
	struct pn533_std_frame *std;
	struct pn533_ext_frame *ext;
	u16 frame_len;
	int i;

	for (i = 0; i + PN533_STD_FRAME_ACK_SIZE <= skb->len; i++) {
		std = (struct pn533_std_frame *)&skb->data[i];
		/* search start code */
		if (std->start_frame != cpu_to_be16(PN533_STD_FRAME_SOF))
			continue;

		/* frame type */
		switch (std->datalen) {
		case PN533_FRAME_DATALEN_ACK:
			if (std->datalen_checksum == 0xff) {
				skb_pull(skb, i);
				return 1;
			}

			break;
		case PN533_FRAME_DATALEN_ERROR:
			if ((std->datalen_checksum == 0xff) &&
					(skb->len >=
					 PN533_STD_ERROR_FRAME_SIZE)) {
				skb_pull(skb, i);
				return 1;
			}

			break;
		case PN533_FRAME_DATALEN_EXTENDED:
			ext = (struct pn533_ext_frame *)&skb->data[i];
			frame_len = be16_to_cpu(ext->datalen);
			if (skb->len >= frame_len +
					sizeof(struct pn533_ext_frame) +
					2 /* CKS + Postamble */) {
				skb_pull(skb, i);
				return 1;
			}

			break;
		default: /* normal information frame */
			frame_len = std->datalen;
			if (skb->len >= frame_len +
					sizeof(struct pn533_std_frame) +
					2 /* CKS + Postamble */) {
				skb_pull(skb, i);
				return 1;
			}

			break;
		}
	}

	return 0;
}

static ssize_t pn532_receive_buf(struct serdev_device *serdev,
				 const u8 *data, size_t count)
{
	struct pn532_uart_phy *dev = serdev_device_get_drvdata(serdev);
	size_t i;

	del_timer(&dev->cmd_timeout);
	for (i = 0; i < count; i++) {
		skb_put_u8(dev->recv_skb, *data++);
		if (!pn532_uart_rx_is_frame(dev->recv_skb))
			continue;

		pn533_recv_frame(dev->priv, dev->recv_skb, 0);
		dev->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
		if (!dev->recv_skb)
			return 0;
	}

	return i;
}

static const struct serdev_device_ops pn532_serdev_ops = {
	.receive_buf = pn532_receive_buf,
	.write_wakeup = serdev_device_write_wakeup,
};

static const struct of_device_id pn532_uart_of_match[] = {
	{ .compatible = "nxp,pn532", },
	{},
};
MODULE_DEVICE_TABLE(of, pn532_uart_of_match);

static int pn532_uart_probe(struct serdev_device *serdev)
{
	struct pn532_uart_phy *pn532;
	struct pn533 *priv;
	int err;

	err = -ENOMEM;
	pn532 = kzalloc(sizeof(*pn532), GFP_KERNEL);
	if (!pn532)
		goto err_exit;

	pn532->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
	if (!pn532->recv_skb)
		goto err_free;

	pn532->serdev = serdev;
	serdev_device_set_drvdata(serdev, pn532);
	serdev_device_set_client_ops(serdev, &pn532_serdev_ops);
	err = serdev_device_open(serdev);
	if (err) {
		dev_err(&serdev->dev, "Unable to open device\n");
		goto err_skb;
	}

	err = serdev_device_set_baudrate(serdev, 115200);
	if (err != 115200) {
		err = -EINVAL;
		goto err_serdev;
	}

	serdev_device_set_flow_control(serdev, false);
	pn532->send_wakeup = PN532_SEND_WAKEUP;
	timer_setup(&pn532->cmd_timeout, pn532_cmd_timeout, 0);
	priv = pn53x_common_init(PN533_DEVICE_PN532_AUTOPOLL,
				     PN533_PROTO_REQ_ACK_RESP,
				     pn532, &uart_phy_ops, NULL,
				     &pn532->serdev->dev);
	if (IS_ERR(priv)) {
		err = PTR_ERR(priv);
		goto err_serdev;
	}

	pn532->priv = priv;
	err = pn533_finalize_setup(pn532->priv);
	if (err)
		goto err_clean;

	serdev_device_close(serdev);
	err = pn53x_register_nfc(priv, PN533_NO_TYPE_B_PROTOCOLS, &serdev->dev);
	if (err) {
		pn53x_common_clean(pn532->priv);
		goto err_skb;
	}

	return err;

err_clean:
	pn53x_common_clean(pn532->priv);
err_serdev:
	serdev_device_close(serdev);
err_skb:
	kfree_skb(pn532->recv_skb);
err_free:
	kfree(pn532);
err_exit:
	return err;
}

static void pn532_uart_remove(struct serdev_device *serdev)
{
	struct pn532_uart_phy *pn532 = serdev_device_get_drvdata(serdev);

	pn53x_unregister_nfc(pn532->priv);
	serdev_device_close(serdev);
	pn53x_common_clean(pn532->priv);
	timer_shutdown_sync(&pn532->cmd_timeout);
	kfree_skb(pn532->recv_skb);
	kfree(pn532);
}

static struct serdev_device_driver pn532_uart_driver = {
	.probe = pn532_uart_probe,
	.remove = pn532_uart_remove,
	.driver = {
		.name = "pn532_uart",
		.of_match_table = pn532_uart_of_match,
	},
};

module_serdev_device_driver(pn532_uart_driver);

MODULE_AUTHOR("Lars Pöschel <poeschel@lemonage.de>");
MODULE_DESCRIPTION("PN532 UART driver");
MODULE_LICENSE("GPL");