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