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 error;
 169
 170         for (;;) {
 171                 if (serio_raw->dead)
 172                         return -ENODEV;
 173
 174                 if (serio_raw->head == serio_raw->tail &&
 175                     (file->f_flags & O_NONBLOCK))
 176                         return -EAGAIN;
 177
 178                 if (count == 0)
 179                         break;
 180
 181                 while (read < count && serio_raw_fetch_byte(serio_raw, &c)) {
 182                         if (put_user(c, buffer++))
 183                                 return -EFAULT;
 184                         read++;
 185                 }
 186
 187                 if (read)
 188                         break;
 189
 190                 if (!(file->f_flags & O_NONBLOCK)) {
 191                         error = wait_event_interruptible(serio_raw->wait,
 192                                         serio_raw->head != serio_raw->tail ||
 193                                         serio_raw->dead);
 194                         if (error)
 195                                 return error;
 196                 }
 197         }
 198
 199         return read;
 200 }
 201
 202 static ssize_t serio_raw_write(struct file *file, const char __user *buffer,
 203                                size_t count, loff_t *ppos)
 204 {
 205         struct serio_raw_client *client = file->private_data;
 206         struct serio_raw *serio_raw = client->serio_raw;
 207         int retval = 0;
 208         unsigned char c;
 209
 210         retval = mutex_lock_interruptible(&serio_raw_mutex);
 211         if (retval)
 212                 return retval;
 213
 214         if (serio_raw->dead) {
 215                 retval = -ENODEV;
 216                 goto out;
 217         }
 218
 219         if (count > 32)
 220                 count = 32;
 221
 222         while (count--) {
 223                 if (get_user(c, buffer++)) {
 224                         retval = -EFAULT;
 225                         goto out;
 226                 }
 227
 228                 if (serio_write(serio_raw->serio, c)) {
 229                         /* Either signal error or partial write */
 230                         if (retval == 0)
 231                                 retval = -EIO;
 232                         goto out;
 233                 }
 234
 235                 retval++;
 236         }
 237
 238 out:
 239         mutex_unlock(&serio_raw_mutex);
 240         return retval;
 241 }
 242
 243 static unsigned int serio_raw_poll(struct file *file, poll_table *wait)
 244 {
 245         struct serio_raw_client *client = file->private_data;
 246         struct serio_raw *serio_raw = client->serio_raw;
 247         unsigned int mask;
 248
 249         poll_wait(file, &serio_raw->wait, wait);
 250
 251         mask = serio_raw->dead ? POLLHUP | POLLERR : POLLOUT | POLLWRNORM;
 252         if (serio_raw->head != serio_raw->tail)
 253                 mask |= POLLIN | POLLRDNORM;
 254
 255         return mask;
 256 }
 257
 258 static const struct file_operations serio_raw_fops = {
 259         .owner          = THIS_MODULE,
 260         .open           = serio_raw_open,
 261         .release        = serio_raw_release,
 262         .read           = serio_raw_read,
 263         .write          = serio_raw_write,
 264         .poll           = serio_raw_poll,
 265         .fasync         = serio_raw_fasync,
 266         .llseek         = noop_llseek,
 267 };
 268
 269
 270 /*********************************************************************
 271  *                   Interface with serio port                       *
 272  *********************************************************************/
 273
 274 static irqreturn_t serio_raw_interrupt(struct serio *serio, unsigned char data,
 275                                         unsigned int dfl)
 276 {
 277         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 278         struct serio_raw_client *client;
 279         unsigned int head = serio_raw->head;
 280
 281         /* we are holding serio->lock here so we are protected */
 282         serio_raw->queue[head] = data;
 283         head = (head + 1) % SERIO_RAW_QUEUE_LEN;
 284         if (likely(head != serio_raw->tail)) {
 285                 serio_raw->head = head;
 286                 list_for_each_entry(client, &serio_raw->client_list, node)
 287                         kill_fasync(&client->fasync, SIGIO, POLL_IN);
 288                 wake_up_interruptible(&serio_raw->wait);
 289         }
 290
 291         return IRQ_HANDLED;
 292 }
 293
 294 static int serio_raw_connect(struct serio *serio, struct serio_driver *drv)
 295 {
 296         static atomic_t serio_raw_no = ATOMIC_INIT(0);
 297         struct serio_raw *serio_raw;
 298         int err;
 299
 300         serio_raw = kzalloc(sizeof(struct serio_raw), GFP_KERNEL);
 301         if (!serio_raw) {
 302                 dev_dbg(&serio->dev, "can't allocate memory for a device\n");
 303                 return -ENOMEM;
 304         }
 305
 306         snprintf(serio_raw->name, sizeof(serio_raw->name),
 307                  "serio_raw%ld", (long)atomic_inc_return(&serio_raw_no) - 1);
 308         kref_init(&serio_raw->kref);
 309         INIT_LIST_HEAD(&serio_raw->client_list);
 310         init_waitqueue_head(&serio_raw->wait);
 311
 312         serio_raw->serio = serio;
 313         get_device(&serio->dev);
 314
 315         serio_set_drvdata(serio, serio_raw);
 316
 317         err = serio_open(serio, drv);
 318         if (err)
 319                 goto err_free;
 320
 321         err = mutex_lock_killable(&serio_raw_mutex);
 322         if (err)
 323                 goto err_close;
 324
 325         list_add_tail(&serio_raw->node, &serio_raw_list);
 326         mutex_unlock(&serio_raw_mutex);
 327
 328         serio_raw->dev.minor = PSMOUSE_MINOR;
 329         serio_raw->dev.name = serio_raw->name;
 330         serio_raw->dev.parent = &serio->dev;
 331         serio_raw->dev.fops = &serio_raw_fops;
 332
 333         err = misc_register(&serio_raw->dev);
 334         if (err) {
 335                 serio_raw->dev.minor = MISC_DYNAMIC_MINOR;
 336                 err = misc_register(&serio_raw->dev);
 337         }
 338
 339         if (err) {
 340                 dev_err(&serio->dev,
 341                         "failed to register raw access device for %s\n",
 342                         serio->phys);
 343                 goto err_unlink;
 344         }
 345
 346         dev_info(&serio->dev, "raw access enabled on %s (%s, minor %d)\n",
 347                  serio->phys, serio_raw->name, serio_raw->dev.minor);
 348         return 0;
 349
 350 err_unlink:
 351         list_del_init(&serio_raw->node);
 352 err_close:
 353         serio_close(serio);
 354 err_free:
 355         serio_set_drvdata(serio, NULL);
 356         kref_put(&serio_raw->kref, serio_raw_free);
 357         return err;
 358 }
 359
 360 static int serio_raw_reconnect(struct serio *serio)
 361 {
 362         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 363         struct serio_driver *drv = serio->drv;
 364
 365         if (!drv || !serio_raw) {
 366                 dev_dbg(&serio->dev,
 367                         "reconnect request, but serio is disconnected, ignoring...\n");
 368                 return -1;
 369         }
 370
 371         /*
 372          * Nothing needs to be done here, we just need this method to
 373          * keep the same device.
 374          */
 375         return 0;
 376 }
 377
 378 /*
 379  * Wake up users waiting for IO so they can disconnect from
 380  * dead device.
 381  */
 382 static void serio_raw_hangup(struct serio_raw *serio_raw)
 383 {
 384         struct serio_raw_client *client;
 385
 386         serio_pause_rx(serio_raw->serio);
 387         list_for_each_entry(client, &serio_raw->client_list, node)
 388                 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
 389         serio_continue_rx(serio_raw->serio);
 390
 391         wake_up_interruptible(&serio_raw->wait);
 392 }
 393
 394
 395 static void serio_raw_disconnect(struct serio *serio)
 396 {
 397         struct serio_raw *serio_raw = serio_get_drvdata(serio);
 398
 399         misc_deregister(&serio_raw->dev);
 400
 401         mutex_lock(&serio_raw_mutex);
 402         serio_raw->dead = true;
 403         list_del_init(&serio_raw->node);
 404         mutex_unlock(&serio_raw_mutex);
 405
 406         serio_raw_hangup(serio_raw);
 407
 408         serio_close(serio);
 409         kref_put(&serio_raw->kref, serio_raw_free);
 410
 411         serio_set_drvdata(serio, NULL);
 412 }
 413
 414 static struct serio_device_id serio_raw_serio_ids[] = {
 415         {
 416                 .type   = SERIO_8042,
 417                 .proto  = SERIO_ANY,
 418                 .id     = SERIO_ANY,
 419                 .extra  = SERIO_ANY,
 420         },
 421         {
 422                 .type   = SERIO_8042_XL,
 423                 .proto  = SERIO_ANY,
 424                 .id     = SERIO_ANY,
 425                 .extra  = SERIO_ANY,
 426         },
 427         { 0 }
 428 };
 429
 430 MODULE_DEVICE_TABLE(serio, serio_raw_serio_ids);
 431
 432 static struct serio_driver serio_raw_drv = {
 433         .driver         = {
 434                 .name   = "serio_raw",
 435         },
 436         .description    = DRIVER_DESC,
 437         .id_table       = serio_raw_serio_ids,
 438         .interrupt      = serio_raw_interrupt,
 439         .connect        = serio_raw_connect,
 440         .reconnect      = serio_raw_reconnect,
 441         .disconnect     = serio_raw_disconnect,
 442         .manual_bind    = true,
 443 };
 444
 445 module_serio_driver(serio_raw_drv);