1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * RainShadow Tech HDMI CEC driver
4 *
5 * Copyright 2016 Hans Verkuil <hverkuil@xs4all.nl
6 */
7
8/*
9 * Notes:
10 *
11 * The higher level protocols are currently disabled. This can be added
12 * later, similar to how this is done for the Pulse Eight CEC driver.
13 *
14 * Documentation of the protocol is available here:
15 *
16 * http://rainshadowtech.com/doc/HDMICECtoUSBandRS232v2.0.pdf
17 */
18
19#include <linux/completion.h>
20#include <linux/ctype.h>
21#include <linux/delay.h>
22#include <linux/init.h>
23#include <linux/interrupt.h>
24#include <linux/kernel.h>
25#include <linux/module.h>
26#include <linux/serio.h>
27#include <linux/slab.h>
28#include <linux/spinlock.h>
29#include <linux/time.h>
30#include <linux/workqueue.h>
31
32#include <media/cec.h>
33
34MODULE_AUTHOR("Hans Verkuil <hverkuil@xs4all.nl>");
35MODULE_DESCRIPTION("RainShadow Tech HDMI CEC driver");
36MODULE_LICENSE("GPL");
37
38#define DATA_SIZE 256
39
40struct rain {
41	struct device *dev;
42	struct serio *serio;
43	struct cec_adapter *adap;
44	struct completion cmd_done;
45	struct work_struct work;
46
47	/* Low-level ringbuffer, collecting incoming characters */
48	char buf[DATA_SIZE];
49	unsigned int buf_rd_idx;
50	unsigned int buf_wr_idx;
51	unsigned int buf_len;
52	spinlock_t buf_lock;
53
54	/* command buffer */
55	char cmd[DATA_SIZE];
56	unsigned int cmd_idx;
57	bool cmd_started;
58
59	/* reply to a command, only used to store the firmware version */
60	char cmd_reply[DATA_SIZE];
61
62	struct mutex write_lock;
63};
64
65static void rain_process_msg(struct rain *rain)
66{
67	struct cec_msg msg = {};
68	const char *cmd = rain->cmd + 3;
69	int stat = -1;
70
71	for (; *cmd; cmd++) {
72		if (!isxdigit(*cmd))
73			continue;
74		if (isxdigit(cmd[0]) && isxdigit(cmd[1])) {
75			if (msg.len == CEC_MAX_MSG_SIZE)
76				break;
77			if (hex2bin(msg.msg + msg.len, cmd, 1))
78				continue;
79			msg.len++;
80			cmd++;
81			continue;
82		}
83		if (!cmd[1])
84			stat = hex_to_bin(cmd[0]);
85		break;
86	}
87
88	if (rain->cmd[0] == 'R') {
89		if (stat == 1 || stat == 2)
90			cec_received_msg(rain->adap, &msg);
91		return;
92	}
93
94	switch (stat) {
95	case 1:
96		cec_transmit_attempt_done(rain->adap, CEC_TX_STATUS_OK);
97		break;
98	case 2:
99		cec_transmit_attempt_done(rain->adap, CEC_TX_STATUS_NACK);
100		break;
101	default:
102		cec_transmit_attempt_done(rain->adap, CEC_TX_STATUS_LOW_DRIVE);
103		break;
104	}
105}
106
107static void rain_irq_work_handler(struct work_struct *work)
108{
109	struct rain *rain =
110		container_of(work, struct rain, work);
111
112	while (true) {
113		unsigned long flags;
114		char data;
115
116		spin_lock_irqsave(&rain->buf_lock, flags);
117		if (!rain->buf_len) {
118			spin_unlock_irqrestore(&rain->buf_lock, flags);
119			break;
120		}
121
122		data = rain->buf[rain->buf_rd_idx];
123		rain->buf_len--;
124		rain->buf_rd_idx = (rain->buf_rd_idx + 1) & 0xff;
125
126		spin_unlock_irqrestore(&rain->buf_lock, flags);
127
128		if (!rain->cmd_started && data != '?')
129			continue;
130
131		switch (data) {
132		case '\r':
133			rain->cmd[rain->cmd_idx] = '\0';
134			dev_dbg(rain->dev, "received: %s\n", rain->cmd);
135			if (!memcmp(rain->cmd, "REC", 3) ||
136			    !memcmp(rain->cmd, "STA", 3)) {
137				rain_process_msg(rain);
138			} else {
139				strscpy(rain->cmd_reply, rain->cmd,
140					sizeof(rain->cmd_reply));
141				complete(&rain->cmd_done);
142			}
143			rain->cmd_idx = 0;
144			rain->cmd_started = false;
145			break;
146
147		case '\n':
148			rain->cmd_idx = 0;
149			rain->cmd_started = false;
150			break;
151
152		case '?':
153			rain->cmd_idx = 0;
154			rain->cmd_started = true;
155			break;
156
157		default:
158			if (rain->cmd_idx >= DATA_SIZE - 1) {
159				dev_dbg(rain->dev,
160					"throwing away %d bytes of garbage\n", rain->cmd_idx);
161				rain->cmd_idx = 0;
162			}
163			rain->cmd[rain->cmd_idx++] = data;
164			break;
165		}
166	}
167}
168
169static irqreturn_t rain_interrupt(struct serio *serio, unsigned char data,
170				    unsigned int flags)
171{
172	struct rain *rain = serio_get_drvdata(serio);
173
174	if (rain->buf_len == DATA_SIZE) {
175		dev_warn_once(rain->dev, "buffer overflow\n");
176		return IRQ_HANDLED;
177	}
178	spin_lock(&rain->buf_lock);
179	rain->buf_len++;
180	rain->buf[rain->buf_wr_idx] = data;
181	rain->buf_wr_idx = (rain->buf_wr_idx + 1) & 0xff;
182	spin_unlock(&rain->buf_lock);
183	schedule_work(&rain->work);
184	return IRQ_HANDLED;
185}
186
187static void rain_disconnect(struct serio *serio)
188{
189	struct rain *rain = serio_get_drvdata(serio);
190
191	cancel_work_sync(&rain->work);
192	cec_unregister_adapter(rain->adap);
193	dev_info(&serio->dev, "disconnected\n");
194	serio_close(serio);
195	serio_set_drvdata(serio, NULL);
196	kfree(rain);
197}
198
199static int rain_send(struct rain *rain, const char *command)
200{
201	int err = serio_write(rain->serio, '!');
202
203	dev_dbg(rain->dev, "send: %s\n", command);
204	while (!err && *command)
205		err = serio_write(rain->serio, *command++);
206	if (!err)
207		err = serio_write(rain->serio, '~');
208
209	return err;
210}
211
212static int rain_send_and_wait(struct rain *rain,
213			      const char *cmd, const char *reply)
214{
215	int err;
216
217	init_completion(&rain->cmd_done);
218
219	mutex_lock(&rain->write_lock);
220	err = rain_send(rain, cmd);
221	if (err)
222		goto err;
223
224	if (!wait_for_completion_timeout(&rain->cmd_done, HZ)) {
225		err = -ETIMEDOUT;
226		goto err;
227	}
228	if (reply && strncmp(rain->cmd_reply, reply, strlen(reply))) {
229		dev_dbg(rain->dev,
230			 "transmit of '%s': received '%s' instead of '%s'\n",
231			 cmd, rain->cmd_reply, reply);
232		err = -EIO;
233	}
234err:
235	mutex_unlock(&rain->write_lock);
236	return err;
237}
238
239static int rain_setup(struct rain *rain, struct serio *serio,
240			struct cec_log_addrs *log_addrs, u16 *pa)
241{
242	int err;
243
244	err = rain_send_and_wait(rain, "R", "REV");
245	if (err)
246		return err;
247	dev_info(rain->dev, "Firmware version %s\n", rain->cmd_reply + 4);
248
249	err = rain_send_and_wait(rain, "Q 1", "QTY");
250	if (err)
251		return err;
252	err = rain_send_and_wait(rain, "c0000", "CFG");
253	if (err)
254		return err;
255	return rain_send_and_wait(rain, "A F 0000", "ADR");
256}
257
258static int rain_cec_adap_enable(struct cec_adapter *adap, bool enable)
259{
260	return 0;
261}
262
263static int rain_cec_adap_log_addr(struct cec_adapter *adap, u8 log_addr)
264{
265	struct rain *rain = cec_get_drvdata(adap);
266	u8 cmd[16];
267
268	if (log_addr == CEC_LOG_ADDR_INVALID)
269		log_addr = CEC_LOG_ADDR_UNREGISTERED;
270	snprintf(cmd, sizeof(cmd), "A %x", log_addr);
271	return rain_send_and_wait(rain, cmd, "ADR");
272}
273
274static int rain_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
275				    u32 signal_free_time, struct cec_msg *msg)
276{
277	struct rain *rain = cec_get_drvdata(adap);
278	char cmd[2 * CEC_MAX_MSG_SIZE + 16];
279	unsigned int i;
280	int err;
281
282	if (msg->len == 1) {
283		snprintf(cmd, sizeof(cmd), "x%x", cec_msg_destination(msg));
284	} else {
285		char hex[3];
286
287		snprintf(cmd, sizeof(cmd), "x%x %02x ",
288			 cec_msg_destination(msg), msg->msg[1]);
289		for (i = 2; i < msg->len; i++) {
290			snprintf(hex, sizeof(hex), "%02x", msg->msg[i]);
291			strlcat(cmd, hex, sizeof(cmd));
292		}
293	}
294	mutex_lock(&rain->write_lock);
295	err = rain_send(rain, cmd);
296	mutex_unlock(&rain->write_lock);
297	return err;
298}
299
300static const struct cec_adap_ops rain_cec_adap_ops = {
301	.adap_enable = rain_cec_adap_enable,
302	.adap_log_addr = rain_cec_adap_log_addr,
303	.adap_transmit = rain_cec_adap_transmit,
304};
305
306static int rain_connect(struct serio *serio, struct serio_driver *drv)
307{
308	u32 caps = CEC_CAP_DEFAULTS | CEC_CAP_PHYS_ADDR | CEC_CAP_MONITOR_ALL;
309	struct rain *rain;
310	int err = -ENOMEM;
311	struct cec_log_addrs log_addrs = {};
312	u16 pa = CEC_PHYS_ADDR_INVALID;
313
314	rain = kzalloc(sizeof(*rain), GFP_KERNEL);
315
316	if (!rain)
317		return -ENOMEM;
318
319	rain->serio = serio;
320	rain->adap = cec_allocate_adapter(&rain_cec_adap_ops, rain,
321					  dev_name(&serio->dev), caps, 1);
322	err = PTR_ERR_OR_ZERO(rain->adap);
323	if (err < 0)
324		goto free_device;
325
326	rain->dev = &serio->dev;
327	serio_set_drvdata(serio, rain);
328	INIT_WORK(&rain->work, rain_irq_work_handler);
329	mutex_init(&rain->write_lock);
330	spin_lock_init(&rain->buf_lock);
331
332	err = serio_open(serio, drv);
333	if (err)
334		goto delete_adap;
335
336	err = rain_setup(rain, serio, &log_addrs, &pa);
337	if (err)
338		goto close_serio;
339
340	err = cec_register_adapter(rain->adap, &serio->dev);
341	if (err < 0)
342		goto close_serio;
343
344	rain->dev = &rain->adap->devnode.dev;
345	return 0;
346
347close_serio:
348	serio_close(serio);
349delete_adap:
350	cec_delete_adapter(rain->adap);
351	serio_set_drvdata(serio, NULL);
352free_device:
353	kfree(rain);
354	return err;
355}
356
357static const struct serio_device_id rain_serio_ids[] = {
358	{
359		.type	= SERIO_RS232,
360		.proto	= SERIO_RAINSHADOW_CEC,
361		.id	= SERIO_ANY,
362		.extra	= SERIO_ANY,
363	},
364	{ 0 }
365};
366
367MODULE_DEVICE_TABLE(serio, rain_serio_ids);
368
369static struct serio_driver rain_drv = {
370	.driver		= {
371		.name	= "rainshadow-cec",
372	},
373	.description	= "RainShadow Tech HDMI CEC driver",
374	.id_table	= rain_serio_ids,
375	.interrupt	= rain_interrupt,
376	.connect	= rain_connect,
377	.disconnect	= rain_disconnect,
378};
379
380module_serio_driver(rain_drv);
381