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 struct evdev {
  27         int open;
  28         int minor;
  29         struct input_handle handle;
  30         wait_queue_head_t wait;
  31         struct evdev_client __rcu *grab;
  32         struct list_head client_list;
  33         spinlock_t client_lock; /* protects client_list */
  34         struct mutex mutex;
  35         struct device dev;
  36         bool exist;
  37 };
  38
  39 struct evdev_client {
  40         int head;
  41         int tail;
  42         spinlock_t buffer_lock; /* protects access to buffer, head and tail */
  43         struct fasync_struct *fasync;
  44         struct evdev *evdev;
  45         struct list_head node;
  46         int bufsize;
  47         struct input_event buffer[];
  48 };
  49
  50 static struct evdev *evdev_table[EVDEV_MINORS];
  51 static DEFINE_MUTEX(evdev_table_mutex);
  52
  53 static void evdev_pass_event(struct evdev_client *client,
  54                              struct input_event *event)
  55 {
  56         /*
  57          * Interrupts are disabled, just acquire the lock.
  58          * Make sure we don't leave with the client buffer
  59          * "empty" by having client->head == client->tail.
  60          */
  61         spin_lock(&client->buffer_lock);
  62         do {
  63                 client->buffer[client->head++] = *event;
  64                 client->head &= client->bufsize - 1;
  65         } while (client->head == client->tail);
  66         spin_unlock(&client->buffer_lock);
  67
  68         if (event->type == EV_SYN)
  69                 kill_fasync(&client->fasync, SIGIO, POLL_IN);
  70 }
  71
  72 /*
  73  * Pass incoming event to all connected clients.
  74  */
  75 static void evdev_event(struct input_handle *handle,
  76                         unsigned int type, unsigned int code, int value)
  77 {
  78         struct evdev *evdev = handle->private;
  79         struct evdev_client *client;
  80         struct input_event event;
  81
  82         do_gettimeofday(&event.time);
  83         event.type = type;
  84         event.code = code;
  85         event.value = value;
  86
  87         rcu_read_lock();
  88
  89         client = rcu_dereference(evdev->grab);
  90         if (client)
  91                 evdev_pass_event(client, &event);
  92         else
  93                 list_for_each_entry_rcu(client, &evdev->client_list, node)
  94                         evdev_pass_event(client, &event);
  95
  96         rcu_read_unlock();
  97
  98         wake_up_interruptible(&evdev->wait);
  99 }
 100
 101 static int evdev_fasync(int fd, struct file *file, int on)
 102 {
 103         struct evdev_client *client = file->private_data;
 104
 105         return fasync_helper(fd, file, on, &client->fasync);
 106 }
 107
 108 static int evdev_flush(struct file *file, fl_owner_t id)
 109 {
 110         struct evdev_client *client = file->private_data;
 111         struct evdev *evdev = client->evdev;
 112         int retval;
 113
 114         retval = mutex_lock_interruptible(&evdev->mutex);
 115         if (retval)
 116                 return retval;
 117
 118         if (!evdev->exist)
 119                 retval = -ENODEV;
 120         else
 121                 retval = input_flush_device(&evdev->handle, file);
 122
 123         mutex_unlock(&evdev->mutex);
 124         return retval;
 125 }
 126
 127 static void evdev_free(struct device *dev)
 128 {
 129         struct evdev *evdev = container_of(dev, struct evdev, dev);
 130
 131         input_put_device(evdev->handle.dev);
 132         kfree(evdev);
 133 }
 134
 135 /*
 136  * Grabs an event device (along with underlying input device).
 137  * This function is called with evdev->mutex taken.
 138  */
 139 static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
 140 {
 141         int error;
 142
 143         if (evdev->grab)
 144                 return -EBUSY;
 145
 146         error = input_grab_device(&evdev->handle);
 147         if (error)
 148                 return error;
 149
 150         rcu_assign_pointer(evdev->grab, client);
 151         synchronize_rcu();
 152
 153         return 0;
 154 }
 155
 156 static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
 157 {
 158         if (evdev->grab != client)
 159                 return  -EINVAL;
 160
 161         rcu_assign_pointer(evdev->grab, NULL);
 162         synchronize_rcu();
 163         input_release_device(&evdev->handle);
 164
 165         return 0;
 166 }
 167
 168 static void evdev_attach_client(struct evdev *evdev,
 169                                 struct evdev_client *client)
 170 {
 171         spin_lock(&evdev->client_lock);
 172         list_add_tail_rcu(&client->node, &evdev->client_list);
 173         spin_unlock(&evdev->client_lock);
 174         synchronize_rcu();
 175 }
 176
 177 static void evdev_detach_client(struct evdev *evdev,
 178                                 struct evdev_client *client)
 179 {
 180         spin_lock(&evdev->client_lock);
 181         list_del_rcu(&client->node);
 182         spin_unlock(&evdev->client_lock);
 183         synchronize_rcu();
 184 }
 185
 186 static int evdev_open_device(struct evdev *evdev)
 187 {
 188         int retval;
 189
 190         retval = mutex_lock_interruptible(&evdev->mutex);
 191         if (retval)
 192                 return retval;
 193
 194         if (!evdev->exist)
 195                 retval = -ENODEV;
 196         else if (!evdev->open++) {
 197                 retval = input_open_device(&evdev->handle);
 198                 if (retval)
 199                         evdev->open--;
 200         }
 201
 202         mutex_unlock(&evdev->mutex);
 203         return retval;
 204 }
 205
 206 static void evdev_close_device(struct evdev *evdev)
 207 {
 208         mutex_lock(&evdev->mutex);
 209
 210         if (evdev->exist && !--evdev->open)
 211                 input_close_device(&evdev->handle);
 212
 213         mutex_unlock(&evdev->mutex);
 214 }
 215
 216 /*
 217  * Wake up users waiting for IO so they can disconnect from
 218  * dead device.
 219  */
 220 static void evdev_hangup(struct evdev *evdev)
 221 {
 222         struct evdev_client *client;
 223
 224         spin_lock(&evdev->client_lock);
 225         list_for_each_entry(client, &evdev->client_list, node)
 226                 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
 227         spin_unlock(&evdev->client_lock);
 228
 229         wake_up_interruptible(&evdev->wait);
 230 }
 231
 232 static int evdev_release(struct inode *inode, struct file *file)
 233 {
 234         struct evdev_client *client = file->private_data;
 235         struct evdev *evdev = client->evdev;
 236
 237         mutex_lock(&evdev->mutex);
 238         if (evdev->grab == client)
 239                 evdev_ungrab(evdev, client);
 240         mutex_unlock(&evdev->mutex);
 241
 242         evdev_detach_client(evdev, client);
 243         kfree(client);
 244
 245         evdev_close_device(evdev);
 246         put_device(&evdev->dev);
 247
 248         return 0;
 249 }
 250
 251 static unsigned int evdev_compute_buffer_size(struct input_dev *dev)
 252 {
 253         unsigned int n_events =
 254                 max(dev->hint_events_per_packet * EVDEV_BUF_PACKETS,
 255                     EVDEV_MIN_BUFFER_SIZE);
 256
 257         return roundup_pow_of_two(n_events);
 258 }
 259
 260 static int evdev_open(struct inode *inode, struct file *file)
 261 {
 262         struct evdev *evdev;
 263         struct evdev_client *client;
 264         int i = iminor(inode) - EVDEV_MINOR_BASE;
 265         unsigned int bufsize;
 266         int error;
 267
 268         if (i >= EVDEV_MINORS)
 269                 return -ENODEV;
 270
 271         error = mutex_lock_interruptible(&evdev_table_mutex);
 272         if (error)
 273                 return error;
 274         evdev = evdev_table[i];
 275         if (evdev)
 276                 get_device(&evdev->dev);
 277         mutex_unlock(&evdev_table_mutex);
 278
 279         if (!evdev)
 280                 return -ENODEV;
 281
 282         bufsize = evdev_compute_buffer_size(evdev->handle.dev);
 283
 284         client = kzalloc(sizeof(struct evdev_client) +
 285                                 bufsize * sizeof(struct input_event),
 286                          GFP_KERNEL);
 287         if (!client) {
 288                 error = -ENOMEM;
 289                 goto err_put_evdev;
 290         }
 291
 292         client->bufsize = bufsize;
 293         spin_lock_init(&client->buffer_lock);
 294         client->evdev = evdev;
 295         evdev_attach_client(evdev, client);
 296
 297         error = evdev_open_device(evdev);
 298         if (error)
 299                 goto err_free_client;
 300
 301         file->private_data = client;
 302         nonseekable_open(inode, file);
 303
 304         return 0;
 305
 306  err_free_client:
 307         evdev_detach_client(evdev, client);
 308         kfree(client);
 309  err_put_evdev:
 310         put_device(&evdev->dev);
 311         return error;
 312 }
 313
 314 static ssize_t evdev_write(struct file *file, const char __user *buffer,
 315                            size_t count, loff_t *ppos)
 316 {
 317         struct evdev_client *client = file->private_data;
 318         struct evdev *evdev = client->evdev;
 319         struct input_event event;
 320         int retval;
 321
 322         retval = mutex_lock_interruptible(&evdev->mutex);
 323         if (retval)
 324                 return retval;
 325
 326         if (!evdev->exist) {
 327                 retval = -ENODEV;
 328                 goto out;
 329         }
 330
 331         while (retval < count) {
 332
 333                 if (input_event_from_user(buffer + retval, &event)) {
 334                         retval = -EFAULT;
 335                         goto out;
 336                 }
 337
 338                 input_inject_event(&evdev->handle,
 339                                    event.type, event.code, event.value);
 340                 retval += input_event_size();
 341         }
 342
 343  out:
 344         mutex_unlock(&evdev->mutex);
 345         return retval;
 346 }
 347
 348 static int evdev_fetch_next_event(struct evdev_client *client,
 349                                   struct input_event *event)
 350 {
 351         int have_event;
 352
 353         spin_lock_irq(&client->buffer_lock);
 354
 355         have_event = client->head != client->tail;
 356         if (have_event) {
 357                 *event = client->buffer[client->tail++];
 358                 client->tail &= client->bufsize - 1;
 359         }
 360
 361         spin_unlock_irq(&client->buffer_lock);
 362
 363         return have_event;
 364 }
 365
 366 static ssize_t evdev_read(struct file *file, char __user *buffer,
 367                           size_t count, loff_t *ppos)
 368 {
 369         struct evdev_client *client = file->private_data;
 370         struct evdev *evdev = client->evdev;
 371         struct input_event event;
 372         int retval;
 373
 374         if (count < input_event_size())
 375                 return -EINVAL;
 376
 377         if (client->head == client->tail && evdev->exist &&
 378             (file->f_flags & O_NONBLOCK))
 379                 return -EAGAIN;
 380
 381         retval = wait_event_interruptible(evdev->wait,
 382                 client->head != client->tail || !evdev->exist);
 383         if (retval)
 384                 return retval;
 385
 386         if (!evdev->exist)
 387                 return -ENODEV;
 388
 389         while (retval + input_event_size() <= count &&
 390                evdev_fetch_next_event(client, &event)) {
 391
 392                 if (input_event_to_user(buffer + retval, &event))
 393                         return -EFAULT;
 394
 395                 retval += input_event_size();
 396         }
 397
 398         return retval;
 399 }
 400
 401 /* No kernel lock - fine */
 402 static unsigned int evdev_poll(struct file *file, poll_table *wait)
 403 {
 404         struct evdev_client *client = file->private_data;
 405         struct evdev *evdev = client->evdev;
 406         unsigned int mask;
 407
 408         poll_wait(file, &evdev->wait, wait);
 409
 410         mask = evdev->exist ? POLLOUT | POLLWRNORM : POLLHUP | POLLERR;
 411         if (client->head != client->tail)
 412                 mask |= POLLIN | POLLRDNORM;
 413
 414         return mask;
 415 }
 416
 417 #ifdef CONFIG_COMPAT
 418
 419 #define BITS_PER_LONG_COMPAT (sizeof(compat_long_t) * 8)
 420 #define BITS_TO_LONGS_COMPAT(x) ((((x) - 1) / BITS_PER_LONG_COMPAT) + 1)
 421
 422 #ifdef __BIG_ENDIAN
 423 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 424                         unsigned int maxlen, void __user *p, int compat)
 425 {
 426         int len, i;
 427
 428         if (compat) {
 429                 len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
 430                 if (len > maxlen)
 431                         len = maxlen;
 432
 433                 for (i = 0; i < len / sizeof(compat_long_t); i++)
 434                         if (copy_to_user((compat_long_t __user *) p + i,
 435                                          (compat_long_t *) bits +
 436                                                 i + 1 - ((i % 2) << 1),
 437                                          sizeof(compat_long_t)))
 438                                 return -EFAULT;
 439         } else {
 440                 len = BITS_TO_LONGS(maxbit) * sizeof(long);
 441                 if (len > maxlen)
 442                         len = maxlen;
 443
 444                 if (copy_to_user(p, bits, len))
 445                         return -EFAULT;
 446         }
 447
 448         return len;
 449 }
 450 #else
 451 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 452                         unsigned int maxlen, void __user *p, int compat)
 453 {
 454         int len = compat ?
 455                         BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t) :
 456                         BITS_TO_LONGS(maxbit) * sizeof(long);
 457
 458         if (len > maxlen)
 459                 len = maxlen;
 460
 461         return copy_to_user(p, bits, len) ? -EFAULT : len;
 462 }
 463 #endif /* __BIG_ENDIAN */
 464
 465 #else
 466
 467 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 468                         unsigned int maxlen, void __user *p, int compat)
 469 {
 470         int len = BITS_TO_LONGS(maxbit) * sizeof(long);
 471
 472         if (len > maxlen)
 473                 len = maxlen;
 474
 475         return copy_to_user(p, bits, len) ? -EFAULT : len;
 476 }
 477
 478 #endif /* CONFIG_COMPAT */
 479
 480 static int str_to_user(const char *str, unsigned int maxlen, void __user *p)
 481 {
 482         int len;
 483
 484         if (!str)
 485                 return -ENOENT;
 486
 487         len = strlen(str) + 1;
 488         if (len > maxlen)
 489                 len = maxlen;
 490
 491         return copy_to_user(p, str, len) ? -EFAULT : len;
 492 }
 493
 494 #define OLD_KEY_MAX     0x1ff
 495 static int handle_eviocgbit(struct input_dev *dev,
 496                             unsigned int type, unsigned int size,
 497                             void __user *p, int compat_mode)
 498 {
 499         static unsigned long keymax_warn_time;
 500         unsigned long *bits;
 501         int len;
 502
 503         switch (type) {
 504
 505         case      0: bits = dev->evbit;  len = EV_MAX;  break;
 506         case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
 507         case EV_REL: bits = dev->relbit; len = REL_MAX; break;
 508         case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
 509         case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
 510         case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
 511         case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
 512         case EV_FF:  bits = dev->ffbit;  len = FF_MAX;  break;
 513         case EV_SW:  bits = dev->swbit;  len = SW_MAX;  break;
 514         default: return -EINVAL;
 515         }
 516
 517         /*
 518          * Work around bugs in userspace programs that like to do
 519          * EVIOCGBIT(EV_KEY, KEY_MAX) and not realize that 'len'
 520          * should be in bytes, not in bits.
 521          */
 522         if (type == EV_KEY && size == OLD_KEY_MAX) {
 523                 len = OLD_KEY_MAX;
 524                 if (printk_timed_ratelimit(&keymax_warn_time, 10 * 1000))
 525                         printk(KERN_WARNING
 526                                 "evdev.c(EVIOCGBIT): Suspicious buffer size %u, "
 527                                 "limiting output to %zu bytes. See "
 528                                 "http://userweb.kernel.org/~dtor/eviocgbit-bug.html\n",
 529                                 OLD_KEY_MAX,
 530                                 BITS_TO_LONGS(OLD_KEY_MAX) * sizeof(long));
 531         }
 532
 533         return bits_to_user(bits, len, size, p, compat_mode);
 534 }
 535 #undef OLD_KEY_MAX
 536
 537 static int evdev_handle_get_keycode(struct input_dev *dev,
 538                                     void __user *p, size_t size)
 539 {
 540         struct input_keymap_entry ke;
 541         int error;
 542
 543         memset(&ke, 0, sizeof(ke));
 544
 545         if (size == sizeof(unsigned int[2])) {
 546                 /* legacy case */
 547                 int __user *ip = (int __user *)p;
 548
 549                 if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 550                         return -EFAULT;
 551
 552                 ke.len = sizeof(unsigned int);
 553                 ke.flags = 0;
 554
 555                 error = input_get_keycode(dev, &ke);
 556                 if (error)
 557                         return error;
 558
 559                 if (put_user(ke.keycode, ip + 1))
 560                         return -EFAULT;
 561
 562         } else {
 563                 size = min(size, sizeof(ke));
 564
 565                 if (copy_from_user(&ke, p, size))
 566                         return -EFAULT;
 567
 568                 error = input_get_keycode(dev, &ke);
 569                 if (error)
 570                         return error;
 571
 572                 if (copy_to_user(p, &ke, size))
 573                         return -EFAULT;
 574         }
 575         return 0;
 576 }
 577
 578 static int evdev_handle_set_keycode(struct input_dev *dev,
 579                                     void __user *p, size_t size)
 580 {
 581         struct input_keymap_entry ke;
 582
 583         memset(&ke, 0, sizeof(ke));
 584
 585         if (size == sizeof(unsigned int[2])) {
 586                 /* legacy case */
 587                 int __user *ip = (int __user *)p;
 588
 589                 if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 590                         return -EFAULT;
 591
 592                 if (get_user(ke.keycode, ip + 1))
 593                         return -EFAULT;
 594
 595                 ke.len = sizeof(unsigned int);
 596                 ke.flags = 0;
 597
 598         } else {
 599                 size = min(size, sizeof(ke));
 600
 601                 if (copy_from_user(&ke, p, size))
 602                         return -EFAULT;
 603
 604                 if (ke.len > sizeof(ke.scancode))
 605                         return -EINVAL;
 606         }
 607
 608         return input_set_keycode(dev, &ke);
 609 }
 610
 611 static long evdev_do_ioctl(struct file *file, unsigned int cmd,
 612                            void __user *p, int compat_mode)
 613 {
 614         struct evdev_client *client = file->private_data;
 615         struct evdev *evdev = client->evdev;
 616         struct input_dev *dev = evdev->handle.dev;
 617         struct input_absinfo abs;
 618         struct ff_effect effect;
 619         int __user *ip = (int __user *)p;
 620         unsigned int i, t, u, v;
 621         unsigned int size;
 622         int error;
 623
 624         /* First we check for fixed-length commands */
 625         switch (cmd) {
 626
 627         case EVIOCGVERSION:
 628                 return put_user(EV_VERSION, ip);
 629
 630         case EVIOCGID:
 631                 if (copy_to_user(p, &dev->id, sizeof(struct input_id)))
 632                         return -EFAULT;
 633                 return 0;
 634
 635         case EVIOCGREP:
 636                 if (!test_bit(EV_REP, dev->evbit))
 637                         return -ENOSYS;
 638                 if (put_user(dev->rep[REP_DELAY], ip))
 639                         return -EFAULT;
 640                 if (put_user(dev->rep[REP_PERIOD], ip + 1))
 641                         return -EFAULT;
 642                 return 0;
 643
 644         case EVIOCSREP:
 645                 if (!test_bit(EV_REP, dev->evbit))
 646                         return -ENOSYS;
 647                 if (get_user(u, ip))
 648                         return -EFAULT;
 649                 if (get_user(v, ip + 1))
 650                         return -EFAULT;
 651
 652                 input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
 653                 input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);
 654
 655                 return 0;
 656
 657         case EVIOCRMFF:
 658                 return input_ff_erase(dev, (int)(unsigned long) p, file);
 659
 660         case EVIOCGEFFECTS:
 661                 i = test_bit(EV_FF, dev->evbit) ?
 662                                 dev->ff->max_effects : 0;
 663                 if (put_user(i, ip))
 664                         return -EFAULT;
 665                 return 0;
 666
 667         case EVIOCGRAB:
 668                 if (p)
 669                         return evdev_grab(evdev, client);
 670                 else
 671                         return evdev_ungrab(evdev, client);
 672         }
 673
 674         size = _IOC_SIZE(cmd);
 675
 676         /* Now check variable-length commands */
 677 #define EVIOC_MASK_SIZE(nr)     ((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
 678         switch (EVIOC_MASK_SIZE(cmd)) {
 679
 680         case EVIOCGKEY(0):
 681                 return bits_to_user(dev->key, KEY_MAX, size, p, compat_mode);
 682
 683         case EVIOCGLED(0):
 684                 return bits_to_user(dev->led, LED_MAX, size, p, compat_mode);
 685
 686         case EVIOCGSND(0):
 687                 return bits_to_user(dev->snd, SND_MAX, size, p, compat_mode);
 688
 689         case EVIOCGSW(0):
 690                 return bits_to_user(dev->sw, SW_MAX, size, p, compat_mode);
 691
 692         case EVIOCGNAME(0):
 693                 return str_to_user(dev->name, size, p);
 694
 695         case EVIOCGPHYS(0):
 696                 return str_to_user(dev->phys, size, p);
 697
 698         case EVIOCGUNIQ(0):
 699                 return str_to_user(dev->uniq, size, p);
 700
 701         case EVIOC_MASK_SIZE(EVIOCSFF):
 702                 if (input_ff_effect_from_user(p, size, &effect))
 703                         return -EFAULT;
 704
 705                 error = input_ff_upload(dev, &effect, file);
 706
 707                 if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
 708                         return -EFAULT;
 709
 710                 return error;
 711
 712         case EVIOC_MASK_SIZE(EVIOCGKEYCODE):
 713                 return evdev_handle_get_keycode(dev, p, size);
 714
 715         case EVIOC_MASK_SIZE(EVIOCSKEYCODE):
 716                 return evdev_handle_set_keycode(dev, p, size);
 717         }
 718
 719         /* Multi-number variable-length handlers */
 720         if (_IOC_TYPE(cmd) != 'E')
 721                 return -EINVAL;
 722
 723         if (_IOC_DIR(cmd) == _IOC_READ) {
 724
 725                 if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
 726                         return handle_eviocgbit(dev,
 727                                                 _IOC_NR(cmd) & EV_MAX, size,
 728                                                 p, compat_mode);
 729
 730                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {
 731
 732                         if (!dev->absinfo)
 733                                 return -EINVAL;
 734
 735                         t = _IOC_NR(cmd) & ABS_MAX;
 736                         abs = dev->absinfo[t];
 737
 738                         if (copy_to_user(p, &abs, min_t(size_t,
 739                                         size, sizeof(struct input_absinfo))))
 740                                 return -EFAULT;
 741
 742                         return 0;
 743                 }
 744         }
 745
 746         if (_IOC_DIR(cmd) == _IOC_WRITE) {
 747
 748                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {
 749
 750                         if (!dev->absinfo)
 751                                 return -EINVAL;
 752
 753                         t = _IOC_NR(cmd) & ABS_MAX;
 754
 755                         if (copy_from_user(&abs, p, min_t(size_t,
 756                                         size, sizeof(struct input_absinfo))))
 757                                 return -EFAULT;
 758
 759                         if (size < sizeof(struct input_absinfo))
 760                                 abs.resolution = 0;
 761
 762                         /* We can't change number of reserved MT slots */
 763                         if (t == ABS_MT_SLOT)
 764                                 return -EINVAL;
 765
 766                         /*
 767                          * Take event lock to ensure that we are not
 768                          * changing device parameters in the middle
 769                          * of event.
 770                          */
 771                         spin_lock_irq(&dev->event_lock);
 772                         dev->absinfo[t] = abs;
 773                         spin_unlock_irq(&dev->event_lock);
 774
 775                         return 0;
 776                 }
 777         }
 778
 779         return -EINVAL;
 780 }
 781
 782 static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
 783                                 void __user *p, int compat_mode)
 784 {
 785         struct evdev_client *client = file->private_data;
 786         struct evdev *evdev = client->evdev;
 787         int retval;
 788
 789         retval = mutex_lock_interruptible(&evdev->mutex);
 790         if (retval)
 791                 return retval;
 792
 793         if (!evdev->exist) {
 794                 retval = -ENODEV;
 795                 goto out;
 796         }
 797
 798         retval = evdev_do_ioctl(file, cmd, p, compat_mode);
 799
 800  out:
 801         mutex_unlock(&evdev->mutex);
 802         return retval;
 803 }
 804
 805 static long evdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 806 {
 807         return evdev_ioctl_handler(file, cmd, (void __user *)arg, 0);
 808 }
 809
 810 #ifdef CONFIG_COMPAT
 811 static long evdev_ioctl_compat(struct file *file,
 812                                 unsigned int cmd, unsigned long arg)
 813 {
 814         return evdev_ioctl_handler(file, cmd, compat_ptr(arg), 1);
 815 }
 816 #endif
 817
 818 static const struct file_operations evdev_fops = {
 819         .owner          = THIS_MODULE,
 820         .read           = evdev_read,
 821         .write          = evdev_write,
 822         .poll           = evdev_poll,
 823         .open           = evdev_open,
 824         .release        = evdev_release,
 825         .unlocked_ioctl = evdev_ioctl,
 826 #ifdef CONFIG_COMPAT
 827         .compat_ioctl   = evdev_ioctl_compat,
 828 #endif
 829         .fasync         = evdev_fasync,
 830         .flush          = evdev_flush,
 831         .llseek         = no_llseek,
 832 };
 833
 834 static int evdev_install_chrdev(struct evdev *evdev)
 835 {
 836         /*
 837          * No need to do any locking here as calls to connect and
 838          * disconnect are serialized by the input core
 839          */
 840         evdev_table[evdev->minor] = evdev;
 841         return 0;
 842 }
 843
 844 static void evdev_remove_chrdev(struct evdev *evdev)
 845 {
 846         /*
 847          * Lock evdev table to prevent race with evdev_open()
 848          */
 849         mutex_lock(&evdev_table_mutex);
 850         evdev_table[evdev->minor] = NULL;
 851         mutex_unlock(&evdev_table_mutex);
 852 }
 853
 854 /*
 855  * Mark device non-existent. This disables writes, ioctls and
 856  * prevents new users from opening the device. Already posted
 857  * blocking reads will stay, however new ones will fail.
 858  */
 859 static void evdev_mark_dead(struct evdev *evdev)
 860 {
 861         mutex_lock(&evdev->mutex);
 862         evdev->exist = false;
 863         mutex_unlock(&evdev->mutex);
 864 }
 865
 866 static void evdev_cleanup(struct evdev *evdev)
 867 {
 868         struct input_handle *handle = &evdev->handle;
 869
 870         evdev_mark_dead(evdev);
 871         evdev_hangup(evdev);
 872         evdev_remove_chrdev(evdev);
 873
 874         /* evdev is marked dead so no one else accesses evdev->open */
 875         if (evdev->open) {
 876                 input_flush_device(handle, NULL);
 877                 input_close_device(handle);
 878         }
 879 }
 880
 881 /*
 882  * Create new evdev device. Note that input core serializes calls
 883  * to connect and disconnect so we don't need to lock evdev_table here.
 884  */
 885 static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
 886                          const struct input_device_id *id)
 887 {
 888         struct evdev *evdev;
 889         int minor;
 890         int error;
 891
 892         for (minor = 0; minor < EVDEV_MINORS; minor++)
 893                 if (!evdev_table[minor])
 894                         break;
 895
 896         if (minor == EVDEV_MINORS) {
 897                 printk(KERN_ERR "evdev: no more free evdev devices\n");
 898                 return -ENFILE;
 899         }
 900
 901         evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
 902         if (!evdev)
 903                 return -ENOMEM;
 904
 905         INIT_LIST_HEAD(&evdev->client_list);
 906         spin_lock_init(&evdev->client_lock);
 907         mutex_init(&evdev->mutex);
 908         init_waitqueue_head(&evdev->wait);
 909
 910         dev_set_name(&evdev->dev, "event%d", minor);
 911         evdev->exist = true;
 912         evdev->minor = minor;
 913
 914         evdev->handle.dev = input_get_device(dev);
 915         evdev->handle.name = dev_name(&evdev->dev);
 916         evdev->handle.handler = handler;
 917         evdev->handle.private = evdev;
 918
 919         evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor);
 920         evdev->dev.class = &input_class;
 921         evdev->dev.parent = &dev->dev;
 922         evdev->dev.release = evdev_free;
 923         device_initialize(&evdev->dev);
 924
 925         error = input_register_handle(&evdev->handle);
 926         if (error)
 927                 goto err_free_evdev;
 928
 929         error = evdev_install_chrdev(evdev);
 930         if (error)
 931                 goto err_unregister_handle;
 932
 933         error = device_add(&evdev->dev);
 934         if (error)
 935                 goto err_cleanup_evdev;
 936
 937         return 0;
 938
 939  err_cleanup_evdev:
 940         evdev_cleanup(evdev);
 941  err_unregister_handle:
 942         input_unregister_handle(&evdev->handle);
 943  err_free_evdev:
 944         put_device(&evdev->dev);
 945         return error;
 946 }
 947
 948 static void evdev_disconnect(struct input_handle *handle)
 949 {
 950         struct evdev *evdev = handle->private;
 951
 952         device_del(&evdev->dev);
 953         evdev_cleanup(evdev);
 954         input_unregister_handle(handle);
 955         put_device(&evdev->dev);
 956 }
 957
 958 static const struct input_device_id evdev_ids[] = {
 959         { .driver_info = 1 },   /* Matches all devices */
 960         { },                    /* Terminating zero entry */
 961 };
 962
 963 MODULE_DEVICE_TABLE(input, evdev_ids);
 964
 965 static struct input_handler evdev_handler = {
 966         .event          = evdev_event,
 967         .connect        = evdev_connect,
 968         .disconnect     = evdev_disconnect,
 969         .fops           = &evdev_fops,
 970         .minor          = EVDEV_MINOR_BASE,
 971         .name           = "evdev",
 972         .id_table       = evdev_ids,
 973 };
 974
 975 static int __init evdev_init(void)
 976 {
 977         return input_register_handler(&evdev_handler);
 978 }
 979
 980 static void __exit evdev_exit(void)
 981 {
 982         input_unregister_handler(&evdev_handler);
 983 }
 984
 985 module_init(evdev_init);
 986 module_exit(evdev_exit);
 987
 988 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
 989 MODULE_DESCRIPTION("Input driver event char devices");
 990 MODULE_LICENSE("GPL");