1 /*
2 * Raw serio device providing access to a raw byte stream from underlying
3 * serio port. Closely emulates behavior of pre-2.6 /dev/psaux device
4 *
5 * Copyright (c) 2004 Dmitry Torokhov
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 as published by
9 * the Free Software Foundation.
10 */
11
12 #include <linux/kref.h>
13 #include <linux/sched.h>
14 #include <linux/slab.h>
15 #include <linux/poll.h>
16 #include <linux/module.h>
17 #include <linux/serio.h>
18 #include <linux/major.h>
19 #include <linux/device.h>
20 #include <linux/miscdevice.h>
21 #include <linux/wait.h>
22 #include <linux/mutex.h>
23
24 #define DRIVER_DESC "Raw serio driver"
25
26 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
27 MODULE_DESCRIPTION(DRIVER_DESC);
28 MODULE_LICENSE("GPL");
29
30 #define SERIO_RAW_QUEUE_LEN 64
31 struct serio_raw {
32 unsigned char queue[SERIO_RAW_QUEUE_LEN];
33 unsigned int tail, head;
34
35 char name[16];
36 struct kref kref;
37 struct serio *serio;
38 struct miscdevice dev;
39 wait_queue_head_t wait;
40 struct list_head client_list;
41 struct list_head node;
42 bool dead;
43 };
44
45 struct serio_raw_client {
46 struct fasync_struct *fasync;
47 struct serio_raw *serio_raw;
48 struct list_head node;
49 };
50
51 static DEFINE_MUTEX(serio_raw_mutex);
52 static LIST_HEAD(serio_raw_list);
53
54 /*********************************************************************
55 * Interface with userspace (file operations) *
56 *********************************************************************/
57
serio_raw_fasync(int fd,struct file * file,int on)58 static int serio_raw_fasync(int fd, struct file *file, int on)
59 {
60 struct serio_raw_client *client = file->private_data;
61
62 return fasync_helper(fd, file, on, &client->fasync);
63 }
64
serio_raw_locate(int minor)65 static struct serio_raw *serio_raw_locate(int minor)
66 {
67 struct serio_raw *serio_raw;
68
69 list_for_each_entry(serio_raw, &serio_raw_list, node) {
70 if (serio_raw->dev.minor == minor)
71 return serio_raw;
72 }
73
74 return NULL;
75 }
76
serio_raw_open(struct inode * inode,struct file * file)77 static int serio_raw_open(struct inode *inode, struct file *file)
78 {
79 struct serio_raw *serio_raw;
80 struct serio_raw_client *client;
81 int retval;
82
83 retval = mutex_lock_interruptible(&serio_raw_mutex);
84 if (retval)
85 return retval;
86
87 serio_raw = serio_raw_locate(iminor(inode));
88 if (!serio_raw) {
89 retval = -ENODEV;
90 goto out;
91 }
92
93 if (serio_raw->dead) {
94 retval = -ENODEV;
95 goto out;
96 }
97
98 client = kzalloc(sizeof(struct serio_raw_client), GFP_KERNEL);
99 if (!client) {
100 retval = -ENOMEM;
101 goto out;
102 }
103
104 client->serio_raw = serio_raw;
105 file->private_data = client;
106
107 kref_get(&serio_raw->kref);
108
109 serio_pause_rx(serio_raw->serio);
110 list_add_tail(&client->node, &serio_raw->client_list);
111 serio_continue_rx(serio_raw->serio);
112
113 out:
114 mutex_unlock(&serio_raw_mutex);
115 return retval;
116 }
117
serio_raw_free(struct kref * kref)118 static void serio_raw_free(struct kref *kref)
119 {
120 struct serio_raw *serio_raw =
121 container_of(kref, struct serio_raw, kref);
122
123 put_device(&serio_raw->serio->dev);
124 kfree(serio_raw);
125 }
126
serio_raw_release(struct inode * inode,struct file * file)127 static int serio_raw_release(struct inode *inode, struct file *file)
128 {
129 struct serio_raw_client *client = file->private_data;
130 struct serio_raw *serio_raw = client->serio_raw;
131
132 serio_pause_rx(serio_raw->serio);
133 list_del(&client->node);
134 serio_continue_rx(serio_raw->serio);
135
136 kfree(client);
137
138 kref_put(&serio_raw->kref, serio_raw_free);
139
140 return 0;
141 }
142
serio_raw_fetch_byte(struct serio_raw * serio_raw,char * c)143 static bool serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
144 {
145 bool empty;
146
147 serio_pause_rx(serio_raw->serio);
148
149 empty = serio_raw->head == serio_raw->tail;
150 if (!empty) {
151 *c = serio_raw->queue[serio_raw->tail];
152 serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
153 }
154
155 serio_continue_rx(serio_raw->serio);
156
157 return !empty;
158 }
159
serio_raw_read(struct file * file,char __user * buffer,size_t count,loff_t * ppos)160 static ssize_t serio_raw_read(struct file *file, char __user *buffer,
161 size_t count, loff_t *ppos)
162 {
163 struct serio_raw_client *client = file->private_data;
164 struct serio_raw *serio_raw = client->serio_raw;
165 char uninitialized_var(c);
166 ssize_t read = 0;
167 int error;
168
169 for (;;) {
170 if (serio_raw->dead)
171 return -ENODEV;
172
173 if (serio_raw->head == serio_raw->tail &&
174 (file->f_flags & O_NONBLOCK))
175 return -EAGAIN;
176
177 if (count == 0)
178 break;
179
180 while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
181 if (put_user(c, buffer++))
182 return -EFAULT;
183 read++;
184 }
185
186 if (read)
187 break;
188
189 if (!(file->f_flags & O_NONBLOCK)) {
190 error = wait_event_interruptible(serio_raw->wait,
191 serio_raw->head != serio_raw->tail ||
192 serio_raw->dead);
193 if (error)
194 return error;
195 }
196 }
197
198 return read;
199 }
200
serio_raw_write(struct file * file,const char __user * buffer,size_t count,loff_t * ppos)201 static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
202 size_t count, loff_t *ppos)
203 {
204 struct serio_raw_client *client = file->private_data;
205 struct serio_raw *serio_raw = client->serio_raw;
206 int retval = 0;
207 unsigned char c;
208
209 retval = mutex_lock_interruptible(&serio_raw_mutex);
210 if (retval)
211 return retval;
212
213 if (serio_raw->dead) {
214 retval = -ENODEV;
215 goto out;
216 }
217
218 if (count > 32)
219 count = 32;
220
221 while (count--) {
222 if (get_user(c, buffer++)) {
223 retval = -EFAULT;
224 goto out;
225 }
226
227 if (serio_write(serio_raw->serio, c)) {
228 /* Either signal error or partial write */
229 if (retval == 0)
230 retval = -EIO;
231 goto out;
232 }
233
234 retval++;
235 }
236
237 out:
238 mutex_unlock(&serio_raw_mutex);
239 return retval;
240 }
241
serio_raw_poll(struct file * file,poll_table * wait)242 static __poll_t serio_raw_poll(struct file *file, poll_table *wait)
243 {
244 struct serio_raw_client *client = file->private_data;
245 struct serio_raw *serio_raw = client->serio_raw;
246 __poll_t mask;
247
248 poll_wait(file, &serio_raw->wait, wait);
249
250 mask = serio_raw->dead ? EPOLLHUP | EPOLLERR : EPOLLOUT | EPOLLWRNORM;
251 if (serio_raw->head != serio_raw->tail)
252 mask |= EPOLLIN | EPOLLRDNORM;
253
254 return mask;
255 }
256
257 static const struct file_operations serio_raw_fops = {
258 .owner = THIS_MODULE,
259 .open = serio_raw_open,
260 .release = serio_raw_release,
261 .read = serio_raw_read,
262 .write = serio_raw_write,
263 .poll = serio_raw_poll,
264 .fasync = serio_raw_fasync,
265 .llseek = noop_llseek,
266 };
267
268
269 /*********************************************************************
270 * Interface with serio port *
271 *********************************************************************/
272
serio_raw_interrupt(struct serio * serio,unsigned char data,unsigned int dfl)273 static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
274 unsigned int dfl)
275 {
276 struct serio_raw *serio_raw = serio_get_drvdata(serio);
277 struct serio_raw_client *client;
278 unsigned int head = serio_raw->head;
279
280 /* we are holding serio->lock here so we are protected */
281 serio_raw->queue[head] = data;
282 head = (head + 1) % SERIO_RAW_QUEUE_LEN;
283 if (likely(head != serio_raw->tail)) {
284 serio_raw->head = head;
285 list_for_each_entry(client, &serio_raw->client_list, node)
286 kill_fasync(&client->fasync, SIGIO, POLL_IN);
287 wake_up_interruptible(&serio_raw->wait);
288 }
289
290 return IRQ_HANDLED;
291 }
292
serio_raw_connect(struct serio * serio,struct serio_driver * drv)293 static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
294 {
295 static atomic_t serio_raw_no = ATOMIC_INIT(-1);
296 struct serio_raw *serio_raw;
297 int err;
298
299 serio_raw = kzalloc(sizeof(struct serio_raw), GFP_KERNEL);
300 if (!serio_raw) {
301 dev_dbg(&serio->dev, "can't allocate memory for a device\n");
302 return -ENOMEM;
303 }
304
305 snprintf(serio_raw->name, sizeof(serio_raw->name),
306 "serio_raw%ld", (long)atomic_inc_return(&serio_raw_no));
307 kref_init(&serio_raw->kref);
308 INIT_LIST_HEAD(&serio_raw->client_list);
309 init_waitqueue_head(&serio_raw->wait);
310
311 serio_raw->serio = serio;
312 get_device(&serio->dev);
313
314 serio_set_drvdata(serio, serio_raw);
315
316 err = serio_open(serio, drv);
317 if (err)
318 goto err_free;
319
320 err = mutex_lock_killable(&serio_raw_mutex);
321 if (err)
322 goto err_close;
323
324 list_add_tail(&serio_raw->node, &serio_raw_list);
325 mutex_unlock(&serio_raw_mutex);
326
327 serio_raw->dev.minor = PSMOUSE_MINOR;
328 serio_raw->dev.name = serio_raw->name;
329 serio_raw->dev.parent = &serio->dev;
330 serio_raw->dev.fops = &serio_raw_fops;
331
332 err = misc_register(&serio_raw->dev);
333 if (err) {
334 serio_raw->dev.minor = MISC_DYNAMIC_MINOR;
335 err = misc_register(&serio_raw->dev);
336 }
337
338 if (err) {
339 dev_err(&serio->dev,
340 "failed to register raw access device for %s\n",
341 serio->phys);
342 goto err_unlink;
343 }
344
345 dev_info(&serio->dev, "raw access enabled on %s (%s, minor %d)\n",
346 serio->phys, serio_raw->name, serio_raw->dev.minor);
347 return 0;
348
349 err_unlink:
350 list_del_init(&serio_raw->node);
351 err_close:
352 serio_close(serio);
353 err_free:
354 serio_set_drvdata(serio, NULL);
355 kref_put(&serio_raw->kref, serio_raw_free);
356 return err;
357 }
358
serio_raw_reconnect(struct serio * serio)359 static int serio_raw_reconnect(struct serio *serio)
360 {
361 struct serio_raw *serio_raw = serio_get_drvdata(serio);
362 struct serio_driver *drv = serio->drv;
363
364 if (!drv || !serio_raw) {
365 dev_dbg(&serio->dev,
366 "reconnect request, but serio is disconnected, ignoring...\n");
367 return -1;
368 }
369
370 /*
371 * Nothing needs to be done here, we just need this method to
372 * keep the same device.
373 */
374 return 0;
375 }
376
377 /*
378 * Wake up users waiting for IO so they can disconnect from
379 * dead device.
380 */
serio_raw_hangup(struct serio_raw * serio_raw)381 static void serio_raw_hangup(struct serio_raw *serio_raw)
382 {
383 struct serio_raw_client *client;
384
385 serio_pause_rx(serio_raw->serio);
386 list_for_each_entry(client, &serio_raw->client_list, node)
387 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
388 serio_continue_rx(serio_raw->serio);
389
390 wake_up_interruptible(&serio_raw->wait);
391 }
392
393
serio_raw_disconnect(struct serio * serio)394 static void serio_raw_disconnect(struct serio *serio)
395 {
396 struct serio_raw *serio_raw = serio_get_drvdata(serio);
397
398 misc_deregister(&serio_raw->dev);
399
400 mutex_lock(&serio_raw_mutex);
401 serio_raw->dead = true;
402 list_del_init(&serio_raw->node);
403 mutex_unlock(&serio_raw_mutex);
404
405 serio_raw_hangup(serio_raw);
406
407 serio_close(serio);
408 kref_put(&serio_raw->kref, serio_raw_free);
409
410 serio_set_drvdata(serio, NULL);
411 }
412
413 static const struct serio_device_id serio_raw_serio_ids[] = {
414 {
415 .type = SERIO_8042,
416 .proto = SERIO_ANY,
417 .id = SERIO_ANY,
418 .extra = SERIO_ANY,
419 },
420 {
421 .type = SERIO_8042_XL,
422 .proto = SERIO_ANY,
423 .id = SERIO_ANY,
424 .extra = SERIO_ANY,
425 },
426 { 0 }
427 };
428
429 MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids);
430
431 static struct serio_driver serio_raw_drv = {
432 .driver = {
433 .name = "serio_raw",
434 },
435 .description = DRIVER_DESC,
436 .id_table = serio_raw_serio_ids,
437 .interrupt = serio_raw_interrupt,
438 .connect = serio_raw_connect,
439 .reconnect = serio_raw_reconnect,
440 .disconnect = serio_raw_disconnect,
441 .manual_bind = true,
442 };
443
444 module_serio_driver(serio_raw_drv);
445
