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/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
  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
  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
  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
 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
 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
 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
 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
 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
 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
 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
 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
 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  */
 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
 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);