drivers/input/serio/serio_raw.c

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