1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Raw serio device providing access to a raw byte stream from underlying
4 * serio port. Closely emulates behavior of pre-2.6 /dev/psaux device
5 *
6 * Copyright (c) 2004 Dmitry Torokhov
7 */
8
9#include <linux/kref.h>
10#include <linux/sched.h>
11#include <linux/slab.h>
12#include <linux/poll.h>
13#include <linux/module.h>
14#include <linux/serio.h>
15#include <linux/major.h>
16#include <linux/device.h>
17#include <linux/miscdevice.h>
18#include <linux/wait.h>
19#include <linux/mutex.h>
20
21#define DRIVER_DESC	"Raw serio driver"
22
23MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
24MODULE_DESCRIPTION(DRIVER_DESC);
25MODULE_LICENSE("GPL");
26
27#define SERIO_RAW_QUEUE_LEN	64
28struct serio_raw {
29	unsigned char queue[SERIO_RAW_QUEUE_LEN];
30	unsigned int tail, head;
31
32	char name[16];
33	struct kref kref;
34	struct serio *serio;
35	struct miscdevice dev;
36	wait_queue_head_t wait;
37	struct list_head client_list;
38	struct list_head node;
39	bool dead;
40};
41
42struct serio_raw_client {
43	struct fasync_struct *fasync;
44	struct serio_raw *serio_raw;
45	struct list_head node;
46};
47
48static DEFINE_MUTEX(serio_raw_mutex);
49static LIST_HEAD(serio_raw_list);
50
51/*********************************************************************
52 *             Interface with userspace (file operations)            *
53 *********************************************************************/
54
55static int serio_raw_fasync(int fd, struct file *file, int on)
56{
57	struct serio_raw_client *client = file->private_data;
58
59	return fasync_helper(fd, file, on, &client->fasync);
60}
61
62static struct serio_raw *serio_raw_locate(int minor)
63{
64	struct serio_raw *serio_raw;
65
66	list_for_each_entry(serio_raw, &serio_raw_list, node) {
67		if (serio_raw->dev.minor == minor)
68			return serio_raw;
69	}
70
71	return NULL;
72}
73
74static int serio_raw_open(struct inode *inode, struct file *file)
75{
76	struct serio_raw *serio_raw;
77	struct serio_raw_client *client;
78	int retval;
79
80	retval = mutex_lock_interruptible(&serio_raw_mutex);
81	if (retval)
82		return retval;
83
84	serio_raw = serio_raw_locate(iminor(inode));
85	if (!serio_raw) {
86		retval = -ENODEV;
87		goto out;
88	}
89
90	if (serio_raw->dead) {
91		retval = -ENODEV;
92		goto out;
93	}
94
95	client = kzalloc(sizeof(struct serio_raw_client), GFP_KERNEL);
96	if (!client) {
97		retval = -ENOMEM;
98		goto out;
99	}
100
101	client->serio_raw = serio_raw;
102	file->private_data = client;
103
104	kref_get(&serio_raw->kref);
105
106	serio_pause_rx(serio_raw->serio);
107	list_add_tail(&client->node, &serio_raw->client_list);
108	serio_continue_rx(serio_raw->serio);
109
110out:
111	mutex_unlock(&serio_raw_mutex);
112	return retval;
113}
114
115static void serio_raw_free(struct kref *kref)
116{
117	struct serio_raw *serio_raw =
118			container_of(kref, struct serio_raw, kref);
119
120	put_device(&serio_raw->serio->dev);
121	kfree(serio_raw);
122}
123
124static int serio_raw_release(struct inode *inode, struct file *file)
125{
126	struct serio_raw_client *client = file->private_data;
127	struct serio_raw *serio_raw = client->serio_raw;
128
129	serio_pause_rx(serio_raw->serio);
130	list_del(&client->node);
131	serio_continue_rx(serio_raw->serio);
132
133	kfree(client);
134
135	kref_put(&serio_raw->kref, serio_raw_free);
136
137	return 0;
138}
139
140static bool serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
141{
142	bool empty;
143
144	serio_pause_rx(serio_raw->serio);
145
146	empty = serio_raw->head == serio_raw->tail;
147	if (!empty) {
148		*c = serio_raw->queue[serio_raw->tail];
149		serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
150	}
151
152	serio_continue_rx(serio_raw->serio);
153
154	return !empty;
155}
156
157static ssize_t serio_raw_read(struct file *file, char __user *buffer,
158			      size_t count, loff_t *ppos)
159{
160	struct serio_raw_client *client = file->private_data;
161	struct serio_raw *serio_raw = client->serio_raw;
162	char c;
163	ssize_t read = 0;
164	int error;
165
166	for (;;) {
167		if (serio_raw->dead)
168			return -ENODEV;
169
170		if (serio_raw->head == serio_raw->tail &&
171		    (file->f_flags & O_NONBLOCK))
172			return -EAGAIN;
173
174		if (count == 0)
175			break;
176
177		while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
178			if (put_user(c, buffer++))
179				return -EFAULT;
180			read++;
181		}
182
183		if (read)
184			break;
185
186		if (!(file->f_flags & O_NONBLOCK)) {
187			error = wait_event_interruptible(serio_raw->wait,
188					serio_raw->head != serio_raw->tail ||
189					serio_raw->dead);
190			if (error)
191				return error;
192		}
193	}
194
195	return read;
196}
197
198static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
199			       size_t count, loff_t *ppos)
200{
201	struct serio_raw_client *client = file->private_data;
202	struct serio_raw *serio_raw = client->serio_raw;
203	int retval = 0;
204	unsigned char c;
205
206	retval = mutex_lock_interruptible(&serio_raw_mutex);
207	if (retval)
208		return retval;
209
210	if (serio_raw->dead) {
211		retval = -ENODEV;
212		goto out;
213	}
214
215	if (count > 32)
216		count = 32;
217
218	while (count--) {
219		if (get_user(c, buffer++)) {
220			retval = -EFAULT;
221			goto out;
222		}
223
224		if (serio_write(serio_raw->serio, c)) {
225			/* Either signal error or partial write */
226			if (retval == 0)
227				retval = -EIO;
228			goto out;
229		}
230
231		retval++;
232	}
233
234out:
235	mutex_unlock(&serio_raw_mutex);
236	return retval;
237}
238
239static __poll_t serio_raw_poll(struct file *file, poll_table *wait)
240{
241	struct serio_raw_client *client = file->private_data;
242	struct serio_raw *serio_raw = client->serio_raw;
243	__poll_t mask;
244
245	poll_wait(file, &serio_raw->wait, wait);
246
247	mask = serio_raw->dead ? EPOLLHUP | EPOLLERR : EPOLLOUT | EPOLLWRNORM;
248	if (serio_raw->head != serio_raw->tail)
249		mask |= EPOLLIN | EPOLLRDNORM;
250
251	return mask;
252}
253
254static const struct file_operations serio_raw_fops = {
255	.owner		= THIS_MODULE,
256	.open		= serio_raw_open,
257	.release	= serio_raw_release,
258	.read		= serio_raw_read,
259	.write		= serio_raw_write,
260	.poll		= serio_raw_poll,
261	.fasync		= serio_raw_fasync,
262	.llseek		= noop_llseek,
263};
264
265
266/*********************************************************************
267 *                   Interface with serio port                       *
268 *********************************************************************/
269
270static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
271					unsigned int dfl)
272{
273	struct serio_raw *serio_raw = serio_get_drvdata(serio);
274	struct serio_raw_client *client;
275	unsigned int head = serio_raw->head;
276
277	/* we are holding serio->lock here so we are protected */
278	serio_raw->queue[head] = data;
279	head = (head + 1) % SERIO_RAW_QUEUE_LEN;
280	if (likely(head != serio_raw->tail)) {
281		serio_raw->head = head;
282		list_for_each_entry(client, &serio_raw->client_list, node)
283			kill_fasync(&client->fasync, SIGIO, POLL_IN);
284		wake_up_interruptible(&serio_raw->wait);
285	}
286
287	return IRQ_HANDLED;
288}
289
290static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
291{
292	static atomic_t serio_raw_no = ATOMIC_INIT(-1);
293	struct serio_raw *serio_raw;
294	int err;
295
296	serio_raw = kzalloc(sizeof(struct serio_raw), GFP_KERNEL);
297	if (!serio_raw) {
298		dev_dbg(&serio->dev, "can't allocate memory for a device\n");
299		return -ENOMEM;
300	}
301
302	snprintf(serio_raw->name, sizeof(serio_raw->name),
303		 "serio_raw%ld", (long)atomic_inc_return(&serio_raw_no));
304	kref_init(&serio_raw->kref);
305	INIT_LIST_HEAD(&serio_raw->client_list);
306	init_waitqueue_head(&serio_raw->wait);
307
308	serio_raw->serio = serio;
309	get_device(&serio->dev);
310
311	serio_set_drvdata(serio, serio_raw);
312
313	err = serio_open(serio, drv);
314	if (err)
315		goto err_free;
316
317	err = mutex_lock_killable(&serio_raw_mutex);
318	if (err)
319		goto err_close;
320
321	list_add_tail(&serio_raw->node, &serio_raw_list);
322	mutex_unlock(&serio_raw_mutex);
323
324	serio_raw->dev.minor = PSMOUSE_MINOR;
325	serio_raw->dev.name = serio_raw->name;
326	serio_raw->dev.parent = &serio->dev;
327	serio_raw->dev.fops = &serio_raw_fops;
328
329	err = misc_register(&serio_raw->dev);
330	if (err) {
331		serio_raw->dev.minor = MISC_DYNAMIC_MINOR;
332		err = misc_register(&serio_raw->dev);
333	}
334
335	if (err) {
336		dev_err(&serio->dev,
337			"failed to register raw access device for %s\n",
338			serio->phys);
339		goto err_unlink;
340	}
341
342	dev_info(&serio->dev, "raw access enabled on %s (%s, minor %d)\n",
343		 serio->phys, serio_raw->name, serio_raw->dev.minor);
344	return 0;
345
346err_unlink:
347	list_del_init(&serio_raw->node);
348err_close:
349	serio_close(serio);
350err_free:
351	serio_set_drvdata(serio, NULL);
352	kref_put(&serio_raw->kref, serio_raw_free);
353	return err;
354}
355
356static int serio_raw_reconnect(struct serio *serio)
357{
358	struct serio_raw *serio_raw = serio_get_drvdata(serio);
359	struct serio_driver *drv = serio->drv;
360
361	if (!drv || !serio_raw) {
362		dev_dbg(&serio->dev,
363			"reconnect request, but serio is disconnected, ignoring...\n");
364		return -1;
365	}
366
367	/*
368	 * Nothing needs to be done here, we just need this method to
369	 * keep the same device.
370	 */
371	return 0;
372}
373
374/*
375 * Wake up users waiting for IO so they can disconnect from
376 * dead device.
377 */
378static void serio_raw_hangup(struct serio_raw *serio_raw)
379{
380	struct serio_raw_client *client;
381
382	serio_pause_rx(serio_raw->serio);
383	list_for_each_entry(client, &serio_raw->client_list, node)
384		kill_fasync(&client->fasync, SIGIO, POLL_HUP);
385	serio_continue_rx(serio_raw->serio);
386
387	wake_up_interruptible(&serio_raw->wait);
388}
389
390
391static void serio_raw_disconnect(struct serio *serio)
392{
393	struct serio_raw *serio_raw = serio_get_drvdata(serio);
394
395	misc_deregister(&serio_raw->dev);
396
397	mutex_lock(&serio_raw_mutex);
398	serio_raw->dead = true;
399	list_del_init(&serio_raw->node);
400	mutex_unlock(&serio_raw_mutex);
401
402	serio_raw_hangup(serio_raw);
403
404	serio_close(serio);
405	kref_put(&serio_raw->kref, serio_raw_free);
406
407	serio_set_drvdata(serio, NULL);
408}
409
410static const struct serio_device_id serio_raw_serio_ids[] = {
411	{
412		.type	= SERIO_8042,
413		.proto	= SERIO_ANY,
414		.id	= SERIO_ANY,
415		.extra	= SERIO_ANY,
416	},
417	{
418		.type	= SERIO_8042_XL,
419		.proto	= SERIO_ANY,
420		.id	= SERIO_ANY,
421		.extra	= SERIO_ANY,
422	},
423	{ 0 }
424};
425
426MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids);
427
428static struct serio_driver serio_raw_drv = {
429	.driver		= {
430		.name	= "serio_raw",
431	},
432	.description	= DRIVER_DESC,
433	.id_table	= serio_raw_serio_ids,
434	.interrupt	= serio_raw_interrupt,
435	.connect	= serio_raw_connect,
436	.reconnect	= serio_raw_reconnect,
437	.disconnect	= serio_raw_disconnect,
438	.manual_bind	= true,
439};
440
441module_serio_driver(serio_raw_drv);
442