1 // SPDX-License-Identifier: GPL-2.0-only
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
6 * Copyright (c) 2004 Dmitry Torokhov
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>
21 #define DRIVER_DESC "Raw serio driver"
23 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
24 MODULE_DESCRIPTION(DRIVER_DESC);
25 MODULE_LICENSE("GPL");
27 #define SERIO_RAW_QUEUE_LEN 64
29 unsigned char queue[SERIO_RAW_QUEUE_LEN];
30 unsigned int tail, head;
35 struct miscdevice dev;
36 wait_queue_head_t wait;
37 struct list_head client_list;
38 struct list_head node;
42 struct serio_raw_client {
43 struct fasync_struct *fasync;
44 struct serio_raw *serio_raw;
45 struct list_head node;
48 static DEFINE_MUTEX(serio_raw_mutex);
49 static LIST_HEAD(serio_raw_list);
51 /*********************************************************************
52 * Interface with userspace (file operations) *
53 *********************************************************************/
55 static int serio_raw_fasync(int fd, struct file *file, int on)
57 struct serio_raw_client *client = file->private_data;
59 return fasync_helper(fd, file, on, &client->fasync);
62 static struct serio_raw *serio_raw_locate(int minor)
64 struct serio_raw *serio_raw;
66 list_for_each_entry(serio_raw, &serio_raw_list, node) {
67 if (serio_raw->dev.minor == minor)
74 static int serio_raw_open(struct inode *inode, struct file *file)
76 struct serio_raw *serio_raw;
77 struct serio_raw_client *client;
80 retval = mutex_lock_interruptible(&serio_raw_mutex);
84 serio_raw = serio_raw_locate(iminor(inode));
90 if (serio_raw->dead) {
95 client = kzalloc(sizeof(struct serio_raw_client), GFP_KERNEL);
101 client->serio_raw = serio_raw;
102 file->private_data = client;
104 kref_get(&serio_raw->kref);
106 serio_pause_rx(serio_raw->serio);
107 list_add_tail(&client->node, &serio_raw->client_list);
108 serio_continue_rx(serio_raw->serio);
111 mutex_unlock(&serio_raw_mutex);
115 static void serio_raw_free(struct kref *kref)
117 struct serio_raw *serio_raw =
118 container_of(kref, struct serio_raw, kref);
120 put_device(&serio_raw->serio->dev);
124 static int serio_raw_release(struct inode *inode, struct file *file)
126 struct serio_raw_client *client = file->private_data;
127 struct serio_raw *serio_raw = client->serio_raw;
129 serio_pause_rx(serio_raw->serio);
130 list_del(&client->node);
131 serio_continue_rx(serio_raw->serio);
135 kref_put(&serio_raw->kref, serio_raw_free);
140 static bool serio_raw_fetch_byte(struct serio_raw *serio_raw, char *c)
144 serio_pause_rx(serio_raw->serio);
146 empty = serio_raw->head == serio_raw->tail;
148 *c = serio_raw->queue[serio_raw->tail];
149 serio_raw->tail = (serio_raw->tail + 1) % SERIO_RAW_QUEUE_LEN;
152 serio_continue_rx(serio_raw->serio);
157 static ssize_t serio_raw_read(struct file *file, char __user *buffer,
158 size_t count, loff_t *ppos)
160 struct serio_raw_client *client = file->private_data;
161 struct serio_raw *serio_raw = client->serio_raw;
170 if (serio_raw->head == serio_raw->tail &&
171 (file->f_flags & O_NONBLOCK))
177 while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
178 if (put_user(c, buffer++))
186 if (!(file->f_flags & O_NONBLOCK)) {
187 error = wait_event_interruptible(serio_raw->wait,
188 serio_raw->head != serio_raw->tail ||
198 static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
199 size_t count, loff_t *ppos)
201 struct serio_raw_client *client = file->private_data;
202 struct serio_raw *serio_raw = client->serio_raw;
206 retval = mutex_lock_interruptible(&serio_raw_mutex);
210 if (serio_raw->dead) {
219 if (get_user(c, buffer++)) {
224 if (serio_write(serio_raw->serio, c)) {
225 /* Either signal error or partial write */
235 mutex_unlock(&serio_raw_mutex);
239 static __poll_t serio_raw_poll(struct file *file, poll_table *wait)
241 struct serio_raw_client *client = file->private_data;
242 struct serio_raw *serio_raw = client->serio_raw;
245 poll_wait(file, &serio_raw->wait, wait);
247 mask = serio_raw->dead ? EPOLLHUP | EPOLLERR : EPOLLOUT | EPOLLWRNORM;
248 if (serio_raw->head != serio_raw->tail)
249 mask |= EPOLLIN | EPOLLRDNORM;
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,
266 /*********************************************************************
267 * Interface with serio port *
268 *********************************************************************/
270 static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
273 struct serio_raw *serio_raw = serio_get_drvdata(serio);
274 struct serio_raw_client *client;
275 unsigned int head = serio_raw->head;
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);
290 static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
292 static atomic_t serio_raw_no = ATOMIC_INIT(-1);
293 struct serio_raw *serio_raw;
296 serio_raw = kzalloc(sizeof(struct serio_raw), GFP_KERNEL);
298 dev_dbg(&serio->dev, "can't allocate memory for a device\n");
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);
308 serio_raw->serio = serio;
309 get_device(&serio->dev);
311 serio_set_drvdata(serio, serio_raw);
313 err = serio_open(serio, drv);
317 err = mutex_lock_killable(&serio_raw_mutex);
321 list_add_tail(&serio_raw->node, &serio_raw_list);
322 mutex_unlock(&serio_raw_mutex);
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;
329 err = misc_register(&serio_raw->dev);
331 serio_raw->dev.minor = MISC_DYNAMIC_MINOR;
332 err = misc_register(&serio_raw->dev);
337 "failed to register raw access device for %s\n",
342 dev_info(&serio->dev, "raw access enabled on %s (%s, minor %d)\n",
343 serio->phys, serio_raw->name, serio_raw->dev.minor);
347 list_del_init(&serio_raw->node);
351 serio_set_drvdata(serio, NULL);
352 kref_put(&serio_raw->kref, serio_raw_free);
356 static int serio_raw_reconnect(struct serio *serio)
358 struct serio_raw *serio_raw = serio_get_drvdata(serio);
359 struct serio_driver *drv = serio->drv;
361 if (!drv || !serio_raw) {
363 "reconnect request, but serio is disconnected, ignoring...\n");
368 * Nothing needs to be done here, we just need this method to
369 * keep the same device.
375 * Wake up users waiting for IO so they can disconnect from
378 static void serio_raw_hangup(struct serio_raw *serio_raw)
380 struct serio_raw_client *client;
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);
387 wake_up_interruptible(&serio_raw->wait);
391 static void serio_raw_disconnect(struct serio *serio)
393 struct serio_raw *serio_raw = serio_get_drvdata(serio);
395 misc_deregister(&serio_raw->dev);
397 mutex_lock(&serio_raw_mutex);
398 serio_raw->dead = true;
399 list_del_init(&serio_raw->node);
400 mutex_unlock(&serio_raw_mutex);
402 serio_raw_hangup(serio_raw);
405 kref_put(&serio_raw->kref, serio_raw_free);
407 serio_set_drvdata(serio, NULL);
410 static const struct serio_device_id serio_raw_serio_ids[] = {
418 .type = SERIO_8042_XL,
426 MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids);
428 static struct serio_driver serio_raw_drv = {
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,
441 module_serio_driver(serio_raw_drv);