drivers/input/evdev.c

   1 /*
   2  * Event char devices, giving access to raw input device events.
   3  *
   4  * Copyright (c) 1999-2002 Vojtech Pavlik
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  */
  10
  11 #define EVDEV_MINOR_BASE        64
  12 #define EVDEV_MINORS            32
  13 #define EVDEV_MIN_BUFFER_SIZE   64U
  14 #define EVDEV_BUF_PACKETS       8
  15
  16 #include <linux/poll.h>
  17 #include <linux/sched.h>
  18 #include <linux/slab.h>
  19 #include <linux/module.h>
  20 #include <linux/init.h>
  21 #include <linux/input.h>
  22 #include <linux/major.h>
  23 #include <linux/device.h>
  24 #include "input-compat.h"
  25
  26 #ifdef CONFIG_SEC_DEBUG_KERNEL_HISTORY
  27 #include <plat/debug-kernel-history.h> /* YUBAEK 20110905 RAMDUMP_DEBUG : added debug-kernel-history.h  */
  28 #endif /* CONFIG_SEC_DEBUG_KERNEL_HISTORY */
  29
  30 struct evdev {
  31         int open;
  32         int minor;
  33         struct input_handle handle;
  34         wait_queue_head_t wait;
  35         struct evdev_client *grab;
  36         struct list_head client_list;
  37         spinlock_t client_lock; /* protects client_list */
  38         struct mutex mutex;
  39         struct device dev;
  40         bool exist;
  41 };
  42
  43 struct evdev_client {
  44         int head;
  45         int tail;
  46         spinlock_t buffer_lock; /* protects access to buffer, head and tail */
  47         struct fasync_struct *fasync;
  48         struct evdev *evdev;
  49         struct list_head node;
  50         int bufsize;
  51         struct input_event buffer[];
  52 };
  53
  54 static struct evdev *evdev_table[EVDEV_MINORS];
  55 static DEFINE_MUTEX(evdev_table_mutex);
  56
  57 static void evdev_pass_event(struct evdev_client *client,
  58                              struct input_event *event)
  59 {
  60         /*
  61          * Interrupts are disabled, just acquire the lock.
  62          * Make sure we don't leave with the client buffer
  63          * "empty" by having client->head == client->tail.
  64          */
  65         spin_lock(&client->buffer_lock);
  66         do {
  67                 client->buffer[client->head++] = *event;
  68                 client->head &= client->bufsize - 1;
  69         } while (client->head == client->tail);
  70         spin_unlock(&client->buffer_lock);
  71
  72         if (event->type == EV_SYN)
  73                 kill_fasync(&client->fasync, SIGIO, POLL_IN);
  74 }
  75
  76 /*
  77  * Pass incoming event to all connected clients.
  78  */
  79 static void evdev_event(struct input_handle *handle,
  80                         unsigned int type, unsigned int code, int value)
  81 {
  82         struct evdev *evdev = handle->private;
  83         struct evdev_client *client;
  84         struct input_event event;
  85
  86         do_gettimeofday(&event.time);
  87         event.type = type;
  88         event.code = code;
  89         event.value = value;
  90
  91         rcu_read_lock();
  92
  93         client = rcu_dereference(evdev->grab);
  94         if (client)
  95                 evdev_pass_event(client, &event);
  96         else
  97                 list_for_each_entry_rcu(client, &evdev->client_list, node)
  98                         evdev_pass_event(client, &event);
  99
 100         rcu_read_unlock();
 101
 102         wake_up_interruptible(&evdev->wait);
 103 }
 104
 105 static int evdev_fasync(int fd, struct file *file, int on)
 106 {
 107         struct evdev_client *client = file->private_data;
 108
 109         return fasync_helper(fd, file, on, &client->fasync);
 110 }
 111
 112 static int evdev_flush(struct file *file, fl_owner_t id)
 113 {
 114         struct evdev_client *client = file->private_data;
 115         struct evdev *evdev = client->evdev;
 116         int retval;
 117
 118         retval = mutex_lock_interruptible(&evdev->mutex);
 119         if (retval)
 120                 return retval;
 121
 122         if (!evdev->exist)
 123                 retval = -ENODEV;
 124         else
 125                 retval = input_flush_device(&evdev->handle, file);
 126
 127         mutex_unlock(&evdev->mutex);
 128         return retval;
 129 }
 130
 131 static void evdev_free(struct device *dev)
 132 {
 133         struct evdev *evdev = container_of(dev, struct evdev, dev);
 134
 135         input_put_device(evdev->handle.dev);
 136         kfree(evdev);
 137 }
 138
 139 /*
 140  * Grabs an event device (along with underlying input device).
 141  * This function is called with evdev->mutex taken.
 142  */
 143 static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
 144 {
 145         int error;
 146
 147         if (evdev->grab)
 148                 return -EBUSY;
 149
 150         error = input_grab_device(&evdev->handle);
 151         if (error)
 152                 return error;
 153
 154         rcu_assign_pointer(evdev->grab, client);
 155         synchronize_rcu();
 156
 157         return 0;
 158 }
 159
 160 static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
 161 {
 162         if (evdev->grab != client)
 163                 return  -EINVAL;
 164
 165         rcu_assign_pointer(evdev->grab, NULL);
 166         synchronize_rcu();
 167         input_release_device(&evdev->handle);
 168
 169         return 0;
 170 }
 171
 172 static void evdev_attach_client(struct evdev *evdev,
 173                                 struct evdev_client *client)
 174 {
 175         spin_lock(&evdev->client_lock);
 176         list_add_tail_rcu(&client->node, &evdev->client_list);
 177         spin_unlock(&evdev->client_lock);
 178         synchronize_rcu();
 179 }
 180
 181 static void evdev_detach_client(struct evdev *evdev,
 182                                 struct evdev_client *client)
 183 {
 184         spin_lock(&evdev->client_lock);
 185         list_del_rcu(&client->node);
 186         spin_unlock(&evdev->client_lock);
 187         synchronize_rcu();
 188 }
 189
 190 static int evdev_open_device(struct evdev *evdev)
 191 {
 192         int retval;
 193
 194         retval = mutex_lock_interruptible(&evdev->mutex);
 195         if (retval)
 196                 return retval;
 197
 198         if (!evdev->exist)
 199                 retval = -ENODEV;
 200         else if (!evdev->open++) {
 201                 retval = input_open_device(&evdev->handle);
 202                 if (retval)
 203                         evdev->open--;
 204         }
 205
 206         mutex_unlock(&evdev->mutex);
 207         return retval;
 208 }
 209
 210 static void evdev_close_device(struct evdev *evdev)
 211 {
 212         mutex_lock(&evdev->mutex);
 213
 214         if (evdev->exist && !--evdev->open)
 215                 input_close_device(&evdev->handle);
 216
 217         mutex_unlock(&evdev->mutex);
 218 }
 219
 220 /*
 221  * Wake up users waiting for IO so they can disconnect from
 222  * dead device.
 223  */
 224 static void evdev_hangup(struct evdev *evdev)
 225 {
 226         struct evdev_client *client;
 227
 228         spin_lock(&evdev->client_lock);
 229         list_for_each_entry(client, &evdev->client_list, node)
 230                 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
 231         spin_unlock(&evdev->client_lock);
 232
 233         wake_up_interruptible(&evdev->wait);
 234 }
 235
 236 static int evdev_release(struct inode *inode, struct file *file)
 237 {
 238         struct evdev_client *client = file->private_data;
 239         struct evdev *evdev = client->evdev;
 240
 241         mutex_lock(&evdev->mutex);
 242         if (evdev->grab == client)
 243                 evdev_ungrab(evdev, client);
 244         mutex_unlock(&evdev->mutex);
 245
 246         evdev_detach_client(evdev, client);
 247         kfree(client);
 248
 249         evdev_close_device(evdev);
 250         put_device(&evdev->dev);
 251
 252         return 0;
 253 }
 254
 255 static unsigned int evdev_compute_buffer_size(struct input_dev *dev)
 256 {
 257         unsigned int n_events =
 258                 max(dev->hint_events_per_packet * EVDEV_BUF_PACKETS,
 259                     EVDEV_MIN_BUFFER_SIZE);
 260
 261         return roundup_pow_of_two(n_events);
 262 }
 263
 264 static int evdev_open(struct inode *inode, struct file *file)
 265 {
 266         struct evdev *evdev;
 267         struct evdev_client *client;
 268         int i = iminor(inode) - EVDEV_MINOR_BASE;
 269         unsigned int bufsize;
 270         int error;
 271
 272         if (i >= EVDEV_MINORS)
 273                 return -ENODEV;
 274
 275         error = mutex_lock_interruptible(&evdev_table_mutex);
 276         if (error)
 277                 return error;
 278         evdev = evdev_table[i];
 279         if (evdev)
 280                 get_device(&evdev->dev);
 281         mutex_unlock(&evdev_table_mutex);
 282
 283         if (!evdev)
 284                 return -ENODEV;
 285
 286         bufsize = evdev_compute_buffer_size(evdev->handle.dev);
 287
 288         client = kzalloc(sizeof(struct evdev_client) +
 289                                 bufsize * sizeof(struct input_event),
 290                          GFP_KERNEL);
 291         if (!client) {
 292                 error = -ENOMEM;
 293                 goto err_put_evdev;
 294         }
 295
 296         client->bufsize = bufsize;
 297         spin_lock_init(&client->buffer_lock);
 298         client->evdev = evdev;
 299         evdev_attach_client(evdev, client);
 300
 301         error = evdev_open_device(evdev);
 302         if (error)
 303                 goto err_free_client;
 304
 305         file->private_data = client;
 306         nonseekable_open(inode, file);
 307
 308         return 0;
 309
 310  err_free_client:
 311         evdev_detach_client(evdev, client);
 312         kfree(client);
 313  err_put_evdev:
 314         put_device(&evdev->dev);
 315         return error;
 316 }
 317
 318 static ssize_t evdev_write(struct file *file, const char __user *buffer,
 319                            size_t count, loff_t *ppos)
 320 {
 321         struct evdev_client *client = file->private_data;
 322         struct evdev *evdev = client->evdev;
 323         struct input_event event;
 324         int retval;
 325
 326         retval = mutex_lock_interruptible(&evdev->mutex);
 327         if (retval)
 328                 return retval;
 329
 330         if (!evdev->exist) {
 331                 retval = -ENODEV;
 332                 goto out;
 333         }
 334
 335         while (retval < count) {
 336
 337                 if (input_event_from_user(buffer + retval, &event)) {
 338                         retval = -EFAULT;
 339                         goto out;
 340                 }
 341
 342                 input_inject_event(&evdev->handle,
 343                                    event.type, event.code, event.value);
 344                 retval += input_event_size();
 345         }
 346
 347  out:
 348         mutex_unlock(&evdev->mutex);
 349         return retval;
 350 }
 351
 352 static int evdev_fetch_next_event(struct evdev_client *client,
 353                                   struct input_event *event)
 354 {
 355         int have_event;
 356
 357         spin_lock_irq(&client->buffer_lock);
 358
 359         have_event = client->head != client->tail;
 360         if (have_event) {
 361                 *event = client->buffer[client->tail++];
 362                 client->tail &= client->bufsize - 1;
 363         }
 364
 365         spin_unlock_irq(&client->buffer_lock);
 366
 367         return have_event;
 368 }
 369
 370 static ssize_t evdev_read(struct file *file, char __user *buffer,
 371                           size_t count, loff_t *ppos)
 372 {
 373         struct evdev_client *client = file->private_data;
 374         struct evdev *evdev = client->evdev;
 375         struct input_event event;
 376         int retval;
 377
 378         if (count < input_event_size())
 379                 return -EINVAL;
 380
 381         if (client->head == client->tail && evdev->exist &&
 382             (file->f_flags & O_NONBLOCK))
 383                 return -EAGAIN;
 384
 385         retval = wait_event_interruptible(evdev->wait,
 386                 client->head != client->tail || !evdev->exist);
 387         if (retval)
 388                 return retval;
 389
 390         if (!evdev->exist)
 391                 return -ENODEV;
 392
 393         while (retval + input_event_size() <= count &&
 394                evdev_fetch_next_event(client, &event)) {
 395
 396                 if (input_event_to_user(buffer + retval, &event))
 397                         return -EFAULT;
 398         /* YUBAEK 20110905 RAMDUMP_DEBUG : added slp_kernel_debug_evdev ++ */
 399         #ifdef CONFIG_SEC_DEBUG_KERNEL_HISTORY
 400                 slp_kernel_debug_evdev(&event);
 401         #endif /* CONFIG_SEC_DEBUG_KERNEL_HISTORY */
 402         /* YUBAEK 20110905 RAMDUMP_DEBUG : added slp_kernel_debug_evdev ++ */
 403                 retval += input_event_size();
 404         }
 405
 406         return retval;
 407 }
 408
 409 /* No kernel lock - fine */
 410 static unsigned int evdev_poll(struct file *file, poll_table *wait)
 411 {
 412         struct evdev_client *client = file->private_data;
 413         struct evdev *evdev = client->evdev;
 414         unsigned int mask;
 415
 416         poll_wait(file, &evdev->wait, wait);
 417
 418         mask = evdev->exist ? POLLOUT | POLLWRNORM : POLLHUP | POLLERR;
 419         if (client->head != client->tail)
 420                 mask |= POLLIN | POLLRDNORM;
 421
 422         return mask;
 423 }
 424
 425 #ifdef CONFIG_COMPAT
 426
 427 #define BITS_PER_LONG_COMPAT (sizeof(compat_long_t) * 8)
 428 #define BITS_TO_LONGS_COMPAT(x) ((((x) - 1) / BITS_PER_LONG_COMPAT) + 1)
 429
 430 #ifdef __BIG_ENDIAN
 431 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 432                         unsigned int maxlen, void __user *p, int compat)
 433 {
 434         int len, i;
 435
 436         if (compat) {
 437                 len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
 438                 if (len > maxlen)
 439                         len = maxlen;
 440
 441                 for (i = 0; i < len / sizeof(compat_long_t); i++)
 442                         if (copy_to_user((compat_long_t __user *) p + i,
 443                                          (compat_long_t *) bits +
 444                                                 i + 1 - ((i % 2) << 1),
 445                                          sizeof(compat_long_t)))
 446                                 return -EFAULT;
 447         } else {
 448                 len = BITS_TO_LONGS(maxbit) * sizeof(long);
 449                 if (len > maxlen)
 450                         len = maxlen;
 451
 452                 if (copy_to_user(p, bits, len))
 453                         return -EFAULT;
 454         }
 455
 456         return len;
 457 }
 458 #else
 459 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 460                         unsigned int maxlen, void __user *p, int compat)
 461 {
 462         int len = compat ?
 463                         BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t) :
 464                         BITS_TO_LONGS(maxbit) * sizeof(long);
 465
 466         if (len > maxlen)
 467                 len = maxlen;
 468
 469         return copy_to_user(p, bits, len) ? -EFAULT : len;
 470 }
 471 #endif /* __BIG_ENDIAN */
 472
 473 #else
 474
 475 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 476                         unsigned int maxlen, void __user *p, int compat)
 477 {
 478         int len = BITS_TO_LONGS(maxbit) * sizeof(long);
 479
 480         if (len > maxlen)
 481                 len = maxlen;
 482
 483         return copy_to_user(p, bits, len) ? -EFAULT : len;
 484 }
 485
 486 #endif /* CONFIG_COMPAT */
 487
 488 static int str_to_user(const char *str, unsigned int maxlen, void __user *p)
 489 {
 490         int len;
 491
 492         if (!str)
 493                 return -ENOENT;
 494
 495         len = strlen(str) + 1;
 496         if (len > maxlen)
 497                 len = maxlen;
 498
 499         return copy_to_user(p, str, len) ? -EFAULT : len;
 500 }
 501
 502 #define OLD_KEY_MAX     0x1ff
 503 static int handle_eviocgbit(struct input_dev *dev,
 504                             unsigned int type, unsigned int size,
 505                             void __user *p, int compat_mode)
 506 {
 507         static unsigned long keymax_warn_time;
 508         unsigned long *bits;
 509         int len;
 510
 511         switch (type) {
 512
 513         case      0: bits = dev->evbit;  len = EV_MAX;  break;
 514         case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
 515         case EV_REL: bits = dev->relbit; len = REL_MAX; break;
 516         case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
 517         case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
 518         case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
 519         case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
 520         case EV_FF:  bits = dev->ffbit;  len = FF_MAX;  break;
 521         case EV_SW:  bits = dev->swbit;  len = SW_MAX;  break;
 522         default: return -EINVAL;
 523         }
 524
 525         /*
 526          * Work around bugs in userspace programs that like to do
 527          * EVIOCGBIT(EV_KEY, KEY_MAX) and not realize that 'len'
 528          * should be in bytes, not in bits.
 529          */
 530         if (type == EV_KEY && size == OLD_KEY_MAX) {
 531                 len = OLD_KEY_MAX;
 532                 if (printk_timed_ratelimit(&keymax_warn_time, 10 * 1000))
 533                         printk(KERN_WARNING
 534                                 "evdev.c(EVIOCGBIT): Suspicious buffer size %u, "
 535                                 "limiting output to %zu bytes. See "
 536                                 "http://userweb.kernel.org/~dtor/eviocgbit-bug.html\n",
 537                                 OLD_KEY_MAX,
 538                                 BITS_TO_LONGS(OLD_KEY_MAX) * sizeof(long));
 539         }
 540
 541         return bits_to_user(bits, len, size, p, compat_mode);
 542 }
 543 #undef OLD_KEY_MAX
 544
 545 static long evdev_do_ioctl(struct file *file, unsigned int cmd,
 546                            void __user *p, int compat_mode)
 547 {
 548         struct evdev_client *client = file->private_data;
 549         struct evdev *evdev = client->evdev;
 550         struct input_dev *dev = evdev->handle.dev;
 551         struct input_absinfo abs;
 552         struct ff_effect effect;
 553         int __user *ip = (int __user *)p;
 554         unsigned int i, t, u, v;
 555         unsigned int size;
 556         int error;
 557
 558         /* First we check for fixed-length commands */
 559         switch (cmd) {
 560
 561         case EVIOCGVERSION:
 562                 return put_user(EV_VERSION, ip);
 563
 564         case EVIOCGID:
 565                 if (copy_to_user(p, &dev->id, sizeof(struct input_id)))
 566                         return -EFAULT;
 567                 return 0;
 568
 569         case EVIOCGREP:
 570                 if (!test_bit(EV_REP, dev->evbit))
 571                         return -ENOSYS;
 572                 if (put_user(dev->rep[REP_DELAY], ip))
 573                         return -EFAULT;
 574                 if (put_user(dev->rep[REP_PERIOD], ip + 1))
 575                         return -EFAULT;
 576                 return 0;
 577
 578         case EVIOCSREP:
 579                 if (!test_bit(EV_REP, dev->evbit))
 580                         return -ENOSYS;
 581                 if (get_user(u, ip))
 582                         return -EFAULT;
 583                 if (get_user(v, ip + 1))
 584                         return -EFAULT;
 585
 586                 input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
 587                 input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);
 588
 589                 return 0;
 590
 591         case EVIOCGKEYCODE:
 592                 if (get_user(t, ip))
 593                         return -EFAULT;
 594
 595                 error = input_get_keycode(dev, t, &v);
 596                 if (error)
 597                         return error;
 598
 599                 if (put_user(v, ip + 1))
 600                         return -EFAULT;
 601
 602                 return 0;
 603
 604         case EVIOCSKEYCODE:
 605                 if (get_user(t, ip) || get_user(v, ip + 1))
 606                         return -EFAULT;
 607
 608                 return input_set_keycode(dev, t, v);
 609
 610         case EVIOCRMFF:
 611                 return input_ff_erase(dev, (int)(unsigned long) p, file);
 612
 613         case EVIOCGEFFECTS:
 614                 i = test_bit(EV_FF, dev->evbit) ?
 615                                 dev->ff->max_effects : 0;
 616                 if (put_user(i, ip))
 617                         return -EFAULT;
 618                 return 0;
 619
 620         case EVIOCGRAB:
 621                 if (p)
 622                         return evdev_grab(evdev, client);
 623                 else
 624                         return evdev_ungrab(evdev, client);
 625         }
 626
 627         size = _IOC_SIZE(cmd);
 628
 629         /* Now check variable-length commands */
 630 #define EVIOC_MASK_SIZE(nr)     ((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
 631
 632         switch (EVIOC_MASK_SIZE(cmd)) {
 633
 634         case EVIOCGKEY(0):
 635                 return bits_to_user(dev->key, KEY_MAX, size, p, compat_mode);
 636
 637         case EVIOCGLED(0):
 638                 return bits_to_user(dev->led, LED_MAX, size, p, compat_mode);
 639
 640         case EVIOCGSND(0):
 641                 return bits_to_user(dev->snd, SND_MAX, size, p, compat_mode);
 642
 643         case EVIOCGSW(0):
 644                 return bits_to_user(dev->sw, SW_MAX, size, p, compat_mode);
 645
 646         case EVIOCGNAME(0):
 647                 return str_to_user(dev->name, size, p);
 648
 649         case EVIOCGPHYS(0):
 650                 return str_to_user(dev->phys, size, p);
 651
 652         case EVIOCGUNIQ(0):
 653                 return str_to_user(dev->uniq, size, p);
 654
 655         case EVIOC_MASK_SIZE(EVIOCSFF):
 656                 if (input_ff_effect_from_user(p, size, &effect))
 657                         return -EFAULT;
 658
 659                 error = input_ff_upload(dev, &effect, file);
 660
 661                 if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
 662                         return -EFAULT;
 663
 664                 return error;
 665         }
 666
 667         /* Multi-number variable-length handlers */
 668         if (_IOC_TYPE(cmd) != 'E')
 669                 return -EINVAL;
 670
 671         if (_IOC_DIR(cmd) == _IOC_READ) {
 672
 673                 if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
 674                         return handle_eviocgbit(dev,
 675                                                 _IOC_NR(cmd) & EV_MAX, size,
 676                                                 p, compat_mode);
 677
 678                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {
 679
 680                         if (!dev->absinfo)
 681                                 return -EINVAL;
 682
 683                         t = _IOC_NR(cmd) & ABS_MAX;
 684                         abs = dev->absinfo[t];
 685
 686                         if (copy_to_user(p, &abs, min_t(size_t,
 687                                         size, sizeof(struct input_absinfo))))
 688                                 return -EFAULT;
 689
 690                         return 0;
 691                 }
 692         }
 693
 694         if (_IOC_DIR(cmd) == _IOC_WRITE) {
 695
 696                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {
 697
 698                         if (!dev->absinfo)
 699                                 return -EINVAL;
 700
 701                         t = _IOC_NR(cmd) & ABS_MAX;
 702
 703                         if (copy_from_user(&abs, p, min_t(size_t,
 704                                         size, sizeof(struct input_absinfo))))
 705                                 return -EFAULT;
 706
 707                         if (size < sizeof(struct input_absinfo))
 708                                 abs.resolution = 0;
 709
 710                         /* We can't change number of reserved MT slots */
 711                         if (t == ABS_MT_SLOT)
 712                                 return -EINVAL;
 713
 714                         /*
 715                          * Take event lock to ensure that we are not
 716                          * changing device parameters in the middle
 717                          * of event.
 718                          */
 719                         spin_lock_irq(&dev->event_lock);
 720                         dev->absinfo[t] = abs;
 721                         spin_unlock_irq(&dev->event_lock);
 722
 723                         return 0;
 724                 }
 725         }
 726
 727         return -EINVAL;
 728 }
 729
 730 static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
 731                                 void __user *p, int compat_mode)
 732 {
 733         struct evdev_client *client = file->private_data;
 734         struct evdev *evdev = client->evdev;
 735         int retval;
 736
 737         retval = mutex_lock_interruptible(&evdev->mutex);
 738         if (retval)
 739                 return retval;
 740
 741         if (!evdev->exist) {
 742                 retval = -ENODEV;
 743                 goto out;
 744         }
 745
 746         retval = evdev_do_ioctl(file, cmd, p, compat_mode);
 747
 748  out:
 749         mutex_unlock(&evdev->mutex);
 750         return retval;
 751 }
 752
 753 static long evdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 754 {
 755         return evdev_ioctl_handler(file, cmd, (void __user *)arg, 0);
 756 }
 757
 758 #ifdef CONFIG_COMPAT
 759 static long evdev_ioctl_compat(struct file *file,
 760                                 unsigned int cmd, unsigned long arg)
 761 {
 762         return evdev_ioctl_handler(file, cmd, compat_ptr(arg), 1);
 763 }
 764 #endif
 765
 766 static const struct file_operations evdev_fops = {
 767         .owner          = THIS_MODULE,
 768         .read           = evdev_read,
 769         .write          = evdev_write,
 770         .poll           = evdev_poll,
 771         .open           = evdev_open,
 772         .release        = evdev_release,
 773         .unlocked_ioctl = evdev_ioctl,
 774 #ifdef CONFIG_COMPAT
 775         .compat_ioctl   = evdev_ioctl_compat,
 776 #endif
 777         .fasync         = evdev_fasync,
 778         .flush          = evdev_flush
 779 };
 780
 781 static int evdev_install_chrdev(struct evdev *evdev)
 782 {
 783         /*
 784          * No need to do any locking here as calls to connect and
 785          * disconnect are serialized by the input core
 786          */
 787         evdev_table[evdev->minor] = evdev;
 788         return 0;
 789 }
 790
 791 static void evdev_remove_chrdev(struct evdev *evdev)
 792 {
 793         /*
 794          * Lock evdev table to prevent race with evdev_open()
 795          */
 796         mutex_lock(&evdev_table_mutex);
 797         evdev_table[evdev->minor] = NULL;
 798         mutex_unlock(&evdev_table_mutex);
 799 }
 800
 801 /*
 802  * Mark device non-existent. This disables writes, ioctls and
 803  * prevents new users from opening the device. Already posted
 804  * blocking reads will stay, however new ones will fail.
 805  */
 806 static void evdev_mark_dead(struct evdev *evdev)
 807 {
 808         mutex_lock(&evdev->mutex);
 809         evdev->exist = false;
 810         mutex_unlock(&evdev->mutex);
 811 }
 812
 813 static void evdev_cleanup(struct evdev *evdev)
 814 {
 815         struct input_handle *handle = &evdev->handle;
 816
 817         evdev_mark_dead(evdev);
 818         evdev_hangup(evdev);
 819         evdev_remove_chrdev(evdev);
 820
 821         /* evdev is marked dead so no one else accesses evdev->open */
 822         if (evdev->open) {
 823                 input_flush_device(handle, NULL);
 824                 input_close_device(handle);
 825         }
 826 }
 827
 828 /*
 829  * Create new evdev device. Note that input core serializes calls
 830  * to connect and disconnect so we don't need to lock evdev_table here.
 831  */
 832 static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
 833                          const struct input_device_id *id)
 834 {
 835         struct evdev *evdev;
 836         int minor;
 837         int error;
 838
 839         for (minor = 0; minor < EVDEV_MINORS; minor++)
 840                 if (!evdev_table[minor])
 841                         break;
 842
 843         if (minor == EVDEV_MINORS) {
 844                 printk(KERN_ERR "evdev: no more free evdev devices\n");
 845                 return -ENFILE;
 846         }
 847
 848         evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
 849         if (!evdev)
 850                 return -ENOMEM;
 851
 852         INIT_LIST_HEAD(&evdev->client_list);
 853         spin_lock_init(&evdev->client_lock);
 854         mutex_init(&evdev->mutex);
 855         init_waitqueue_head(&evdev->wait);
 856
 857         dev_set_name(&evdev->dev, "event%d", minor);
 858         evdev->exist = true;
 859         evdev->minor = minor;
 860
 861         evdev->handle.dev = input_get_device(dev);
 862         evdev->handle.name = dev_name(&evdev->dev);
 863         evdev->handle.handler = handler;
 864         evdev->handle.private = evdev;
 865
 866         evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor);
 867         evdev->dev.class = &input_class;
 868         evdev->dev.parent = &dev->dev;
 869         evdev->dev.release = evdev_free;
 870         device_initialize(&evdev->dev);
 871
 872         error = input_register_handle(&evdev->handle);
 873         if (error)
 874                 goto err_free_evdev;
 875
 876         error = evdev_install_chrdev(evdev);
 877         if (error)
 878                 goto err_unregister_handle;
 879
 880         error = device_add(&evdev->dev);
 881         if (error)
 882                 goto err_cleanup_evdev;
 883
 884         return 0;
 885
 886  err_cleanup_evdev:
 887         evdev_cleanup(evdev);
 888  err_unregister_handle:
 889         input_unregister_handle(&evdev->handle);
 890  err_free_evdev:
 891         put_device(&evdev->dev);
 892         return error;
 893 }
 894
 895 static void evdev_disconnect(struct input_handle *handle)
 896 {
 897         struct evdev *evdev = handle->private;
 898
 899         device_del(&evdev->dev);
 900         evdev_cleanup(evdev);
 901         input_unregister_handle(handle);
 902         put_device(&evdev->dev);
 903 }
 904
 905 static const struct input_device_id evdev_ids[] = {
 906         { .driver_info = 1 },   /* Matches all devices */
 907         { },                    /* Terminating zero entry */
 908 };
 909
 910 MODULE_DEVICE_TABLE(input, evdev_ids);
 911
 912 static struct input_handler evdev_handler = {
 913         .event          = evdev_event,
 914         .connect        = evdev_connect,
 915         .disconnect     = evdev_disconnect,
 916         .fops           = &evdev_fops,
 917         .minor          = EVDEV_MINOR_BASE,
 918         .name           = "evdev",
 919         .id_table       = evdev_ids,
 920 };
 921
 922 static int __init evdev_init(void)
 923 {
 924         return input_register_handler(&evdev_handler);
 925 }
 926
 927 static void __exit evdev_exit(void)
 928 {
 929         input_unregister_handler(&evdev_handler);
 930 }
 931
 932 module_init(evdev_init);
 933 module_exit(evdev_exit);
 934
 935 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
 936 MODULE_DESCRIPTION("Input driver event char devices");
 937 MODULE_LICENSE("GPL");