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[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 | |
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 | |
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 | |
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 | |
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 | int retval; |
79 | |
80 | retval = mutex_lock_interruptible(&serio_raw_mutex); |
81 | if (retval) |
82 | return retval; |
83 | |
84 | serio_raw = serio_raw_locate(minor: 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(size: 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(kref: &serio_raw->kref); |
105 | |
106 | serio_pause_rx(serio: serio_raw->serio); |
107 | list_add_tail(new: &client->node, head: &serio_raw->client_list); |
108 | serio_continue_rx(serio: serio_raw->serio); |
109 | |
110 | out: |
111 | mutex_unlock(lock: &serio_raw_mutex); |
112 | return retval; |
113 | } |
114 | |
115 | static 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(dev: &serio_raw->serio->dev); |
121 | kfree(objp: serio_raw); |
122 | } |
123 | |
124 | static 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: serio_raw->serio); |
130 | list_del(entry: &client->node); |
131 | serio_continue_rx(serio: serio_raw->serio); |
132 | |
133 | kfree(objp: client); |
134 | |
135 | kref_put(kref: &serio_raw->kref, release: serio_raw_free); |
136 | |
137 | return 0; |
138 | } |
139 | |
140 | static bool serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c) |
141 | { |
142 | bool empty; |
143 | |
144 | serio_pause_rx(serio: 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: serio_raw->serio); |
153 | |
154 | return !empty; |
155 | } |
156 | |
157 | static 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: &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 | |
198 | static 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: serio_raw->serio, data: c)) { |
225 | /* Either signal error or partial write */ |
226 | if (retval == 0) |
227 | retval = -EIO; |
228 | goto out; |
229 | } |
230 | |
231 | retval++; |
232 | } |
233 | |
234 | out: |
235 | mutex_unlock(lock: &serio_raw_mutex); |
236 | return retval; |
237 | } |
238 | |
239 | static __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(filp: file, wait_address: &serio_raw->wait, p: 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 | |
254 | static 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 | |
270 | static 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 | |
290 | static 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(size: 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(buf: serio_raw->name, size: sizeof(serio_raw->name), |
303 | fmt: "serio_raw%ld" , (long)atomic_inc_return(v: &serio_raw_no)); |
304 | kref_init(kref: &serio_raw->kref); |
305 | INIT_LIST_HEAD(list: &serio_raw->client_list); |
306 | init_waitqueue_head(&serio_raw->wait); |
307 | |
308 | serio_raw->serio = serio; |
309 | get_device(dev: &serio->dev); |
310 | |
311 | serio_set_drvdata(serio, data: 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(new: &serio_raw->node, head: &serio_raw_list); |
322 | mutex_unlock(lock: &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(misc: &serio_raw->dev); |
330 | if (err) { |
331 | serio_raw->dev.minor = MISC_DYNAMIC_MINOR; |
332 | err = misc_register(misc: &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 | |
346 | err_unlink: |
347 | list_del_init(entry: &serio_raw->node); |
348 | err_close: |
349 | serio_close(serio); |
350 | err_free: |
351 | serio_set_drvdata(serio, NULL); |
352 | kref_put(kref: &serio_raw->kref, release: serio_raw_free); |
353 | return err; |
354 | } |
355 | |
356 | static 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 | */ |
378 | static void serio_raw_hangup(struct serio_raw *serio_raw) |
379 | { |
380 | struct serio_raw_client *client; |
381 | |
382 | serio_pause_rx(serio: 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: serio_raw->serio); |
386 | |
387 | wake_up_interruptible(&serio_raw->wait); |
388 | } |
389 | |
390 | |
391 | static void serio_raw_disconnect(struct serio *serio) |
392 | { |
393 | struct serio_raw *serio_raw = serio_get_drvdata(serio); |
394 | |
395 | misc_deregister(misc: &serio_raw->dev); |
396 | |
397 | mutex_lock(&serio_raw_mutex); |
398 | serio_raw->dead = true; |
399 | list_del_init(entry: &serio_raw->node); |
400 | mutex_unlock(lock: &serio_raw_mutex); |
401 | |
402 | serio_raw_hangup(serio_raw); |
403 | |
404 | serio_close(serio); |
405 | kref_put(kref: &serio_raw->kref, release: serio_raw_free); |
406 | |
407 | serio_set_drvdata(serio, NULL); |
408 | } |
409 | |
410 | static 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 | |
426 | MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids); |
427 | |
428 | static 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 | |
441 | module_serio_driver(serio_raw_drv); |
442 | |