xref: /openbmc/linux/drivers/nfc/pn533/uart.c (revision 292a089d)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Driver for NXP PN532 NFC Chip - UART transport layer
4  *
5  * Copyright (C) 2018 Lemonage Software GmbH
6  * Author: Lars Pöschel <poeschel@lemonage.de>
7  * All rights reserved.
8  */
9 
10 #include <linux/device.h>
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/nfc.h>
14 #include <linux/netdevice.h>
15 #include <linux/of.h>
16 #include <linux/serdev.h>
17 #include "pn533.h"
18 
19 #define PN532_UART_SKB_BUFF_LEN	(PN533_CMD_DATAEXCH_DATA_MAXLEN * 2)
20 
21 enum send_wakeup {
22 	PN532_SEND_NO_WAKEUP = 0,
23 	PN532_SEND_WAKEUP,
24 	PN532_SEND_LAST_WAKEUP,
25 };
26 
27 
28 struct pn532_uart_phy {
29 	struct serdev_device *serdev;
30 	struct sk_buff *recv_skb;
31 	struct pn533 *priv;
32 	/*
33 	 * send_wakeup variable is used to control if we need to send a wakeup
34 	 * request to the pn532 chip prior to our actual command. There is a
35 	 * little propability of a race condition. We decided to not mutex the
36 	 * variable as the worst that could happen is, that we send a wakeup
37 	 * to the chip that is already awake. This does not hurt. It is a
38 	 * no-op to the chip.
39 	 */
40 	enum send_wakeup send_wakeup;
41 	struct timer_list cmd_timeout;
42 	struct sk_buff *cur_out_buf;
43 };
44 
pn532_uart_send_frame(struct pn533 * dev,struct sk_buff * out)45 static int pn532_uart_send_frame(struct pn533 *dev,
46 				struct sk_buff *out)
47 {
48 	/* wakeup sequence and dummy bytes for waiting time */
49 	static const u8 wakeup[] = {
50 		0x55, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
51 		0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
52 	struct pn532_uart_phy *pn532 = dev->phy;
53 	int err;
54 
55 	print_hex_dump_debug("PN532_uart TX: ", DUMP_PREFIX_NONE, 16, 1,
56 			     out->data, out->len, false);
57 
58 	pn532->cur_out_buf = out;
59 	if (pn532->send_wakeup) {
60 		err = serdev_device_write(pn532->serdev,
61 				wakeup, sizeof(wakeup),
62 				MAX_SCHEDULE_TIMEOUT);
63 		if (err < 0)
64 			return err;
65 	}
66 
67 	if (pn532->send_wakeup == PN532_SEND_LAST_WAKEUP)
68 		pn532->send_wakeup = PN532_SEND_NO_WAKEUP;
69 
70 	err = serdev_device_write(pn532->serdev, out->data, out->len,
71 			MAX_SCHEDULE_TIMEOUT);
72 	if (err < 0)
73 		return err;
74 
75 	mod_timer(&pn532->cmd_timeout, HZ / 40 + jiffies);
76 	return 0;
77 }
78 
pn532_uart_send_ack(struct pn533 * dev,gfp_t flags)79 static int pn532_uart_send_ack(struct pn533 *dev, gfp_t flags)
80 {
81 	/* spec 7.1.1.3:  Preamble, SoPC (2), ACK Code (2), Postamble */
82 	static const u8 ack[PN533_STD_FRAME_ACK_SIZE] = {
83 			0x00, 0x00, 0xff, 0x00, 0xff, 0x00};
84 	struct pn532_uart_phy *pn532 = dev->phy;
85 	int err;
86 
87 	err = serdev_device_write(pn532->serdev, ack, sizeof(ack),
88 			MAX_SCHEDULE_TIMEOUT);
89 	if (err < 0)
90 		return err;
91 
92 	return 0;
93 }
94 
pn532_uart_abort_cmd(struct pn533 * dev,gfp_t flags)95 static void pn532_uart_abort_cmd(struct pn533 *dev, gfp_t flags)
96 {
97 	/* An ack will cancel the last issued command */
98 	pn532_uart_send_ack(dev, flags);
99 	/* schedule cmd_complete_work to finish current command execution */
100 	pn533_recv_frame(dev, NULL, -ENOENT);
101 }
102 
pn532_dev_up(struct pn533 * dev)103 static int pn532_dev_up(struct pn533 *dev)
104 {
105 	struct pn532_uart_phy *pn532 = dev->phy;
106 	int ret = 0;
107 
108 	ret = serdev_device_open(pn532->serdev);
109 	if (ret)
110 		return ret;
111 
112 	pn532->send_wakeup = PN532_SEND_LAST_WAKEUP;
113 	return ret;
114 }
115 
pn532_dev_down(struct pn533 * dev)116 static int pn532_dev_down(struct pn533 *dev)
117 {
118 	struct pn532_uart_phy *pn532 = dev->phy;
119 
120 	serdev_device_close(pn532->serdev);
121 	pn532->send_wakeup = PN532_SEND_WAKEUP;
122 
123 	return 0;
124 }
125 
126 static const struct pn533_phy_ops uart_phy_ops = {
127 	.send_frame = pn532_uart_send_frame,
128 	.send_ack = pn532_uart_send_ack,
129 	.abort_cmd = pn532_uart_abort_cmd,
130 	.dev_up = pn532_dev_up,
131 	.dev_down = pn532_dev_down,
132 };
133 
pn532_cmd_timeout(struct timer_list * t)134 static void pn532_cmd_timeout(struct timer_list *t)
135 {
136 	struct pn532_uart_phy *dev = from_timer(dev, t, cmd_timeout);
137 
138 	pn532_uart_send_frame(dev->priv, dev->cur_out_buf);
139 }
140 
141 /*
142  * scans the buffer if it contains a pn532 frame. It is not checked if the
143  * frame is really valid. This is later done with pn533_rx_frame_is_valid.
144  * This is useful for malformed or errornous transmitted frames. Adjusts the
145  * bufferposition where the frame starts, since pn533_recv_frame expects a
146  * well formed frame.
147  */
pn532_uart_rx_is_frame(struct sk_buff * skb)148 static int pn532_uart_rx_is_frame(struct sk_buff *skb)
149 {
150 	struct pn533_std_frame *std;
151 	struct pn533_ext_frame *ext;
152 	u16 frame_len;
153 	int i;
154 
155 	for (i = 0; i + PN533_STD_FRAME_ACK_SIZE <= skb->len; i++) {
156 		std = (struct pn533_std_frame *)&skb->data[i];
157 		/* search start code */
158 		if (std->start_frame != cpu_to_be16(PN533_STD_FRAME_SOF))
159 			continue;
160 
161 		/* frame type */
162 		switch (std->datalen) {
163 		case PN533_FRAME_DATALEN_ACK:
164 			if (std->datalen_checksum == 0xff) {
165 				skb_pull(skb, i);
166 				return 1;
167 			}
168 
169 			break;
170 		case PN533_FRAME_DATALEN_ERROR:
171 			if ((std->datalen_checksum == 0xff) &&
172 					(skb->len >=
173 					 PN533_STD_ERROR_FRAME_SIZE)) {
174 				skb_pull(skb, i);
175 				return 1;
176 			}
177 
178 			break;
179 		case PN533_FRAME_DATALEN_EXTENDED:
180 			ext = (struct pn533_ext_frame *)&skb->data[i];
181 			frame_len = be16_to_cpu(ext->datalen);
182 			if (skb->len >= frame_len +
183 					sizeof(struct pn533_ext_frame) +
184 					2 /* CKS + Postamble */) {
185 				skb_pull(skb, i);
186 				return 1;
187 			}
188 
189 			break;
190 		default: /* normal information frame */
191 			frame_len = std->datalen;
192 			if (skb->len >= frame_len +
193 					sizeof(struct pn533_std_frame) +
194 					2 /* CKS + Postamble */) {
195 				skb_pull(skb, i);
196 				return 1;
197 			}
198 
199 			break;
200 		}
201 	}
202 
203 	return 0;
204 }
205 
pn532_receive_buf(struct serdev_device * serdev,const unsigned char * data,size_t count)206 static int pn532_receive_buf(struct serdev_device *serdev,
207 		const unsigned char *data, size_t count)
208 {
209 	struct pn532_uart_phy *dev = serdev_device_get_drvdata(serdev);
210 	size_t i;
211 
212 	del_timer(&dev->cmd_timeout);
213 	for (i = 0; i < count; i++) {
214 		skb_put_u8(dev->recv_skb, *data++);
215 		if (!pn532_uart_rx_is_frame(dev->recv_skb))
216 			continue;
217 
218 		pn533_recv_frame(dev->priv, dev->recv_skb, 0);
219 		dev->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
220 		if (!dev->recv_skb)
221 			return 0;
222 	}
223 
224 	return i;
225 }
226 
227 static const struct serdev_device_ops pn532_serdev_ops = {
228 	.receive_buf = pn532_receive_buf,
229 	.write_wakeup = serdev_device_write_wakeup,
230 };
231 
232 static const struct of_device_id pn532_uart_of_match[] = {
233 	{ .compatible = "nxp,pn532", },
234 	{},
235 };
236 MODULE_DEVICE_TABLE(of, pn532_uart_of_match);
237 
pn532_uart_probe(struct serdev_device * serdev)238 static int pn532_uart_probe(struct serdev_device *serdev)
239 {
240 	struct pn532_uart_phy *pn532;
241 	struct pn533 *priv;
242 	int err;
243 
244 	err = -ENOMEM;
245 	pn532 = kzalloc(sizeof(*pn532), GFP_KERNEL);
246 	if (!pn532)
247 		goto err_exit;
248 
249 	pn532->recv_skb = alloc_skb(PN532_UART_SKB_BUFF_LEN, GFP_KERNEL);
250 	if (!pn532->recv_skb)
251 		goto err_free;
252 
253 	pn532->serdev = serdev;
254 	serdev_device_set_drvdata(serdev, pn532);
255 	serdev_device_set_client_ops(serdev, &pn532_serdev_ops);
256 	err = serdev_device_open(serdev);
257 	if (err) {
258 		dev_err(&serdev->dev, "Unable to open device\n");
259 		goto err_skb;
260 	}
261 
262 	err = serdev_device_set_baudrate(serdev, 115200);
263 	if (err != 115200) {
264 		err = -EINVAL;
265 		goto err_serdev;
266 	}
267 
268 	serdev_device_set_flow_control(serdev, false);
269 	pn532->send_wakeup = PN532_SEND_WAKEUP;
270 	timer_setup(&pn532->cmd_timeout, pn532_cmd_timeout, 0);
271 	priv = pn53x_common_init(PN533_DEVICE_PN532_AUTOPOLL,
272 				     PN533_PROTO_REQ_ACK_RESP,
273 				     pn532, &uart_phy_ops, NULL,
274 				     &pn532->serdev->dev);
275 	if (IS_ERR(priv)) {
276 		err = PTR_ERR(priv);
277 		goto err_serdev;
278 	}
279 
280 	pn532->priv = priv;
281 	err = pn533_finalize_setup(pn532->priv);
282 	if (err)
283 		goto err_clean;
284 
285 	serdev_device_close(serdev);
286 	err = pn53x_register_nfc(priv, PN533_NO_TYPE_B_PROTOCOLS, &serdev->dev);
287 	if (err) {
288 		pn53x_common_clean(pn532->priv);
289 		goto err_skb;
290 	}
291 
292 	return err;
293 
294 err_clean:
295 	pn53x_common_clean(pn532->priv);
296 err_serdev:
297 	serdev_device_close(serdev);
298 err_skb:
299 	kfree_skb(pn532->recv_skb);
300 err_free:
301 	kfree(pn532);
302 err_exit:
303 	return err;
304 }
305 
pn532_uart_remove(struct serdev_device * serdev)306 static void pn532_uart_remove(struct serdev_device *serdev)
307 {
308 	struct pn532_uart_phy *pn532 = serdev_device_get_drvdata(serdev);
309 
310 	pn53x_unregister_nfc(pn532->priv);
311 	serdev_device_close(serdev);
312 	pn53x_common_clean(pn532->priv);
313 	timer_shutdown_sync(&pn532->cmd_timeout);
314 	kfree_skb(pn532->recv_skb);
315 	kfree(pn532);
316 }
317 
318 static struct serdev_device_driver pn532_uart_driver = {
319 	.probe = pn532_uart_probe,
320 	.remove = pn532_uart_remove,
321 	.driver = {
322 		.name = "pn532_uart",
323 		.of_match_table = pn532_uart_of_match,
324 	},
325 };
326 
327 module_serdev_device_driver(pn532_uart_driver);
328 
329 MODULE_AUTHOR("Lars Pöschel <poeschel@lemonage.de>");
330 MODULE_DESCRIPTION("PN532 UART driver");
331 MODULE_LICENSE("GPL");
332