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 pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #define EVDEV_MINOR_BASE        64
  14 #define EVDEV_MINORS            32
  15 #define EVDEV_MIN_BUFFER_SIZE   64U
  16 #define EVDEV_BUF_PACKETS       8
  17
  18 #include <linux/poll.h>
  19 #include <linux/sched.h>
  20 #include <linux/slab.h>
  21 #include <linux/module.h>
  22 #include <linux/init.h>
  23 #include <linux/input.h>
  24 #include <linux/major.h>
  25 #include <linux/device.h>
  26 #include "input-compat.h"
  27
  28 struct evdev {
  29         int open;
  30         int minor;
  31         struct input_handle handle;
  32         wait_queue_head_t wait;
  33         struct evdev_client __rcu *grab;
  34         struct list_head client_list;
  35         spinlock_t client_lock; /* protects client_list */
  36         struct mutex mutex;
  37         struct device dev;
  38         bool exist;
  39 };
  40
  41 struct evdev_client {
  42         int head;
  43         int tail;
  44         spinlock_t buffer_lock; /* protects access to buffer, head and tail */
  45         struct fasync_struct *fasync;
  46         struct evdev *evdev;
  47         struct list_head node;
  48         int bufsize;
  49         struct input_event buffer[];
  50 };
  51
  52 static struct evdev *evdev_table[EVDEV_MINORS];
  53 static DEFINE_MUTEX(evdev_table_mutex);
  54
  55 static void evdev_pass_event(struct evdev_client *client,
  56                              struct input_event *event)
  57 {
  58         /*
  59          * Interrupts are disabled, just acquire the lock.
  60          * Make sure we don't leave with the client buffer
  61          * "empty" by having client->head == client->tail.
  62          */
  63         spin_lock(&client->buffer_lock);
  64         do {
  65                 client->buffer[client->head++] = *event;
  66                 client->head &= client->bufsize - 1;
  67         } while (client->head == client->tail);
  68         spin_unlock(&client->buffer_lock);
  69
  70         if (event->type == EV_SYN)
  71                 kill_fasync(&client->fasync, SIGIO, POLL_IN);
  72 }
  73
  74 /*
  75  * Pass incoming event to all connected clients.
  76  */
  77 static void evdev_event(struct input_handle *handle,
  78                         unsigned int type, unsigned int code, int value)
  79 {
  80         struct evdev *evdev = handle->private;
  81         struct evdev_client *client;
  82         struct input_event event;
  83
  84         do_gettimeofday(&event.time);
  85         event.type = type;
  86         event.code = code;
  87         event.value = value;
  88
  89         rcu_read_lock();
  90
  91         client = rcu_dereference(evdev->grab);
  92         if (client)
  93                 evdev_pass_event(client, &event);
  94         else
  95                 list_for_each_entry_rcu(client, &evdev->client_list, node)
  96                         evdev_pass_event(client, &event);
  97
  98         rcu_read_unlock();
  99
 100         wake_up_interruptible(&evdev->wait);
 101 }
 102
 103 static int evdev_fasync(int fd, struct file *file, int on)
 104 {
 105         struct evdev_client *client = file->private_data;
 106
 107         return fasync_helper(fd, file, on, &client->fasync);
 108 }
 109
 110 static int evdev_flush(struct file *file, fl_owner_t id)
 111 {
 112         struct evdev_client *client = file->private_data;
 113         struct evdev *evdev = client->evdev;
 114         int retval;
 115
 116         retval = mutex_lock_interruptible(&evdev->mutex);
 117         if (retval)
 118                 return retval;
 119
 120         if (!evdev->exist)
 121                 retval = -ENODEV;
 122         else
 123                 retval = input_flush_device(&evdev->handle, file);
 124
 125         mutex_unlock(&evdev->mutex);
 126         return retval;
 127 }
 128
 129 static void evdev_free(struct device *dev)
 130 {
 131         struct evdev *evdev = container_of(dev, struct evdev, dev);
 132
 133         input_put_device(evdev->handle.dev);
 134         kfree(evdev);
 135 }
 136
 137 /*
 138  * Grabs an event device (along with underlying input device).
 139  * This function is called with evdev->mutex taken.
 140  */
 141 static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
 142 {
 143         int error;
 144
 145         if (evdev->grab)
 146                 return -EBUSY;
 147
 148         error = input_grab_device(&evdev->handle);
 149         if (error)
 150                 return error;
 151
 152         rcu_assign_pointer(evdev->grab, client);
 153         synchronize_rcu();
 154
 155         return 0;
 156 }
 157
 158 static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
 159 {
 160         if (evdev->grab != client)
 161                 return  -EINVAL;
 162
 163         rcu_assign_pointer(evdev->grab, NULL);
 164         synchronize_rcu();
 165         input_release_device(&evdev->handle);
 166
 167         return 0;
 168 }
 169
 170 static void evdev_attach_client(struct evdev *evdev,
 171                                 struct evdev_client *client)
 172 {
 173         spin_lock(&evdev->client_lock);
 174         list_add_tail_rcu(&client->node, &evdev->client_list);
 175         spin_unlock(&evdev->client_lock);
 176         synchronize_rcu();
 177 }
 178
 179 static void evdev_detach_client(struct evdev *evdev,
 180                                 struct evdev_client *client)
 181 {
 182         spin_lock(&evdev->client_lock);
 183         list_del_rcu(&client->node);
 184         spin_unlock(&evdev->client_lock);
 185         synchronize_rcu();
 186 }
 187
 188 static int evdev_open_device(struct evdev *evdev)
 189 {
 190         int retval;
 191
 192         retval = mutex_lock_interruptible(&evdev->mutex);
 193         if (retval)
 194                 return retval;
 195
 196         if (!evdev->exist)
 197                 retval = -ENODEV;
 198         else if (!evdev->open++) {
 199                 retval = input_open_device(&evdev->handle);
 200                 if (retval)
 201                         evdev->open--;
 202         }
 203
 204         mutex_unlock(&evdev->mutex);
 205         return retval;
 206 }
 207
 208 static void evdev_close_device(struct evdev *evdev)
 209 {
 210         mutex_lock(&evdev->mutex);
 211
 212         if (evdev->exist && !--evdev->open)
 213                 input_close_device(&evdev->handle);
 214
 215         mutex_unlock(&evdev->mutex);
 216 }
 217
 218 /*
 219  * Wake up users waiting for IO so they can disconnect from
 220  * dead device.
 221  */
 222 static void evdev_hangup(struct evdev *evdev)
 223 {
 224         struct evdev_client *client;
 225
 226         spin_lock(&evdev->client_lock);
 227         list_for_each_entry(client, &evdev->client_list, node)
 228                 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
 229         spin_unlock(&evdev->client_lock);
 230
 231         wake_up_interruptible(&evdev->wait);
 232 }
 233
 234 static int evdev_release(struct inode *inode, struct file *file)
 235 {
 236         struct evdev_client *client = file->private_data;
 237         struct evdev *evdev = client->evdev;
 238
 239         mutex_lock(&evdev->mutex);
 240         if (evdev->grab == client)
 241                 evdev_ungrab(evdev, client);
 242         mutex_unlock(&evdev->mutex);
 243
 244         evdev_detach_client(evdev, client);
 245         kfree(client);
 246
 247         evdev_close_device(evdev);
 248         put_device(&evdev->dev);
 249
 250         return 0;
 251 }
 252
 253 static unsigned int evdev_compute_buffer_size(struct input_dev *dev)
 254 {
 255         unsigned int n_events =
 256                 max(dev->hint_events_per_packet * EVDEV_BUF_PACKETS,
 257                     EVDEV_MIN_BUFFER_SIZE);
 258
 259         return roundup_pow_of_two(n_events);
 260 }
 261
 262 static int evdev_open(struct inode *inode, struct file *file)
 263 {
 264         struct evdev *evdev;
 265         struct evdev_client *client;
 266         int i = iminor(inode) - EVDEV_MINOR_BASE;
 267         unsigned int bufsize;
 268         int error;
 269
 270         if (i >= EVDEV_MINORS)
 271                 return -ENODEV;
 272
 273         error = mutex_lock_interruptible(&evdev_table_mutex);
 274         if (error)
 275                 return error;
 276         evdev = evdev_table[i];
 277         if (evdev)
 278                 get_device(&evdev->dev);
 279         mutex_unlock(&evdev_table_mutex);
 280
 281         if (!evdev)
 282                 return -ENODEV;
 283
 284         bufsize = evdev_compute_buffer_size(evdev->handle.dev);
 285
 286         client = kzalloc(sizeof(struct evdev_client) +
 287                                 bufsize * sizeof(struct input_event),
 288                          GFP_KERNEL);
 289         if (!client) {
 290                 error = -ENOMEM;
 291                 goto err_put_evdev;
 292         }
 293
 294         client->bufsize = bufsize;
 295         spin_lock_init(&client->buffer_lock);
 296         client->evdev = evdev;
 297         evdev_attach_client(evdev, client);
 298
 299         error = evdev_open_device(evdev);
 300         if (error)
 301                 goto err_free_client;
 302
 303         file->private_data = client;
 304         nonseekable_open(inode, file);
 305
 306         return 0;
 307
 308  err_free_client:
 309         evdev_detach_client(evdev, client);
 310         kfree(client);
 311  err_put_evdev:
 312         put_device(&evdev->dev);
 313         return error;
 314 }
 315
 316 static ssize_t evdev_write(struct file *file, const char __user *buffer,
 317                            size_t count, loff_t *ppos)
 318 {
 319         struct evdev_client *client = file->private_data;
 320         struct evdev *evdev = client->evdev;
 321         struct input_event event;
 322         int retval;
 323
 324         retval = mutex_lock_interruptible(&evdev->mutex);
 325         if (retval)
 326                 return retval;
 327
 328         if (!evdev->exist) {
 329                 retval = -ENODEV;
 330                 goto out;
 331         }
 332
 333         while (retval < count) {
 334
 335                 if (input_event_from_user(buffer + retval, &event)) {
 336                         retval = -EFAULT;
 337                         goto out;
 338                 }
 339
 340                 input_inject_event(&evdev->handle,
 341                                    event.type, event.code, event.value);
 342                 retval += input_event_size();
 343         }
 344
 345  out:
 346         mutex_unlock(&evdev->mutex);
 347         return retval;
 348 }
 349
 350 static int evdev_fetch_next_event(struct evdev_client *client,
 351                                   struct input_event *event)
 352 {
 353         int have_event;
 354
 355         spin_lock_irq(&client->buffer_lock);
 356
 357         have_event = client->head != client->tail;
 358         if (have_event) {
 359                 *event = client->buffer[client->tail++];
 360                 client->tail &= client->bufsize - 1;
 361         }
 362
 363         spin_unlock_irq(&client->buffer_lock);
 364
 365         return have_event;
 366 }
 367
 368 static ssize_t evdev_read(struct file *file, char __user *buffer,
 369                           size_t count, loff_t *ppos)
 370 {
 371         struct evdev_client *client = file->private_data;
 372         struct evdev *evdev = client->evdev;
 373         struct input_event event;
 374         int retval;
 375
 376         if (count < input_event_size())
 377                 return -EINVAL;
 378
 379         if (client->head == client->tail && evdev->exist &&
 380             (file->f_flags & O_NONBLOCK))
 381                 return -EAGAIN;
 382
 383         retval = wait_event_interruptible(evdev->wait,
 384                 client->head != client->tail || !evdev->exist);
 385         if (retval)
 386                 return retval;
 387
 388         if (!evdev->exist)
 389                 return -ENODEV;
 390
 391         while (retval + input_event_size() <= count &&
 392                evdev_fetch_next_event(client, &event)) {
 393
 394                 if (input_event_to_user(buffer + retval, &event))
 395                         return -EFAULT;
 396
 397                 retval += input_event_size();
 398         }
 399
 400         return retval;
 401 }
 402
 403 /* No kernel lock - fine */
 404 static unsigned int evdev_poll(struct file *file, poll_table *wait)
 405 {
 406         struct evdev_client *client = file->private_data;
 407         struct evdev *evdev = client->evdev;
 408         unsigned int mask;
 409
 410         poll_wait(file, &evdev->wait, wait);
 411
 412         mask = evdev->exist ? POLLOUT | POLLWRNORM : POLLHUP | POLLERR;
 413         if (client->head != client->tail)
 414                 mask |= POLLIN | POLLRDNORM;
 415
 416         return mask;
 417 }
 418
 419 #ifdef CONFIG_COMPAT
 420
 421 #define BITS_PER_LONG_COMPAT (sizeof(compat_long_t) * 8)
 422 #define BITS_TO_LONGS_COMPAT(x) ((((x) - 1) / BITS_PER_LONG_COMPAT) + 1)
 423
 424 #ifdef __BIG_ENDIAN
 425 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 426                         unsigned int maxlen, void __user *p, int compat)
 427 {
 428         int len, i;
 429
 430         if (compat) {
 431                 len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
 432                 if (len > maxlen)
 433                         len = maxlen;
 434
 435                 for (i = 0; i < len / sizeof(compat_long_t); i++)
 436                         if (copy_to_user((compat_long_t __user *) p + i,
 437                                          (compat_long_t *) bits +
 438                                                 i + 1 - ((i % 2) << 1),
 439                                          sizeof(compat_long_t)))
 440                                 return -EFAULT;
 441         } else {
 442                 len = BITS_TO_LONGS(maxbit) * sizeof(long);
 443                 if (len > maxlen)
 444                         len = maxlen;
 445
 446                 if (copy_to_user(p, bits, len))
 447                         return -EFAULT;
 448         }
 449
 450         return len;
 451 }
 452 #else
 453 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 454                         unsigned int maxlen, void __user *p, int compat)
 455 {
 456         int len = compat ?
 457                         BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t) :
 458                         BITS_TO_LONGS(maxbit) * sizeof(long);
 459
 460         if (len > maxlen)
 461                 len = maxlen;
 462
 463         return copy_to_user(p, bits, len) ? -EFAULT : len;
 464 }
 465 #endif /* __BIG_ENDIAN */
 466
 467 #else
 468
 469 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 470                         unsigned int maxlen, void __user *p, int compat)
 471 {
 472         int len = BITS_TO_LONGS(maxbit) * sizeof(long);
 473
 474         if (len > maxlen)
 475                 len = maxlen;
 476
 477         return copy_to_user(p, bits, len) ? -EFAULT : len;
 478 }
 479
 480 #endif /* CONFIG_COMPAT */
 481
 482 static int str_to_user(const char *str, unsigned int maxlen, void __user *p)
 483 {
 484         int len;
 485
 486         if (!str)
 487                 return -ENOENT;
 488
 489         len = strlen(str) + 1;
 490         if (len > maxlen)
 491                 len = maxlen;
 492
 493         return copy_to_user(p, str, len) ? -EFAULT : len;
 494 }
 495
 496 #define OLD_KEY_MAX     0x1ff
 497 static int handle_eviocgbit(struct input_dev *dev,
 498                             unsigned int type, unsigned int size,
 499                             void __user *p, int compat_mode)
 500 {
 501         static unsigned long keymax_warn_time;
 502         unsigned long *bits;
 503         int len;
 504
 505         switch (type) {
 506
 507         case      0: bits = dev->evbit;  len = EV_MAX;  break;
 508         case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
 509         case EV_REL: bits = dev->relbit; len = REL_MAX; break;
 510         case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
 511         case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
 512         case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
 513         case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
 514         case EV_FF:  bits = dev->ffbit;  len = FF_MAX;  break;
 515         case EV_SW:  bits = dev->swbit;  len = SW_MAX;  break;
 516         default: return -EINVAL;
 517         }
 518
 519         /*
 520          * Work around bugs in userspace programs that like to do
 521          * EVIOCGBIT(EV_KEY, KEY_MAX) and not realize that 'len'
 522          * should be in bytes, not in bits.
 523          */
 524         if (type == EV_KEY && size == OLD_KEY_MAX) {
 525                 len = OLD_KEY_MAX;
 526                 if (printk_timed_ratelimit(&keymax_warn_time, 10 * 1000))
 527                         pr_warning("(EVIOCGBIT): Suspicious buffer size %u, "
 528                                    "limiting output to %zu bytes. See "
 529                                    "http://userweb.kernel.org/~dtor/eviocgbit-bug.html\n",
 530                                    OLD_KEY_MAX,
 531                                    BITS_TO_LONGS(OLD_KEY_MAX) * sizeof(long));
 532         }
 533
 534         return bits_to_user(bits, len, size, p, compat_mode);
 535 }
 536 #undef OLD_KEY_MAX
 537
 538 static int evdev_handle_get_keycode(struct input_dev *dev,
 539                                     void __user *p, size_t size)
 540 {
 541         struct input_keymap_entry ke;
 542         int error;
 543
 544         memset(&ke, 0, sizeof(ke));
 545
 546         if (size == sizeof(unsigned int[2])) {
 547                 /* legacy case */
 548                 int __user *ip = (int __user *)p;
 549
 550                 if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 551                         return -EFAULT;
 552
 553                 ke.len = sizeof(unsigned int);
 554                 ke.flags = 0;
 555
 556                 error = input_get_keycode(dev, &ke);
 557                 if (error)
 558                         return error;
 559
 560                 if (put_user(ke.keycode, ip + 1))
 561                         return -EFAULT;
 562
 563         } else {
 564                 size = min(size, sizeof(ke));
 565
 566                 if (copy_from_user(&ke, p, size))
 567                         return -EFAULT;
 568
 569                 error = input_get_keycode(dev, &ke);
 570                 if (error)
 571                         return error;
 572
 573                 if (copy_to_user(p, &ke, size))
 574                         return -EFAULT;
 575         }
 576         return 0;
 577 }
 578
 579 static int evdev_handle_set_keycode(struct input_dev *dev,
 580                                     void __user *p, size_t size)
 581 {
 582         struct input_keymap_entry ke;
 583
 584         memset(&ke, 0, sizeof(ke));
 585
 586         if (size == sizeof(unsigned int[2])) {
 587                 /* legacy case */
 588                 int __user *ip = (int __user *)p;
 589
 590                 if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 591                         return -EFAULT;
 592
 593                 if (get_user(ke.keycode, ip + 1))
 594                         return -EFAULT;
 595
 596                 ke.len = sizeof(unsigned int);
 597                 ke.flags = 0;
 598
 599         } else {
 600                 size = min(size, sizeof(ke));
 601
 602                 if (copy_from_user(&ke, p, size))
 603                         return -EFAULT;
 604
 605                 if (ke.len > sizeof(ke.scancode))
 606                         return -EINVAL;
 607         }
 608
 609         return input_set_keycode(dev, &ke);
 610 }
 611
 612 static long evdev_do_ioctl(struct file *file, unsigned int cmd,
 613                            void __user *p, int compat_mode)
 614 {
 615         struct evdev_client *client = file->private_data;
 616         struct evdev *evdev = client->evdev;
 617         struct input_dev *dev = evdev->handle.dev;
 618         struct input_absinfo abs;
 619         struct ff_effect effect;
 620         int __user *ip = (int __user *)p;
 621         unsigned int i, t, u, v;
 622         unsigned int size;
 623         int error;
 624
 625         /* First we check for fixed-length commands */
 626         switch (cmd) {
 627
 628         case EVIOCGVERSION:
 629                 return put_user(EV_VERSION, ip);
 630
 631         case EVIOCGID:
 632                 if (copy_to_user(p, &dev->id, sizeof(struct input_id)))
 633                         return -EFAULT;
 634                 return 0;
 635
 636         case EVIOCGREP:
 637                 if (!test_bit(EV_REP, dev->evbit))
 638                         return -ENOSYS;
 639                 if (put_user(dev->rep[REP_DELAY], ip))
 640                         return -EFAULT;
 641                 if (put_user(dev->rep[REP_PERIOD], ip + 1))
 642                         return -EFAULT;
 643                 return 0;
 644
 645         case EVIOCSREP:
 646                 if (!test_bit(EV_REP, dev->evbit))
 647                         return -ENOSYS;
 648                 if (get_user(u, ip))
 649                         return -EFAULT;
 650                 if (get_user(v, ip + 1))
 651                         return -EFAULT;
 652
 653                 input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
 654                 input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);
 655
 656                 return 0;
 657
 658         case EVIOCRMFF:
 659                 return input_ff_erase(dev, (int)(unsigned long) p, file);
 660
 661         case EVIOCGEFFECTS:
 662                 i = test_bit(EV_FF, dev->evbit) ?
 663                                 dev->ff->max_effects : 0;
 664                 if (put_user(i, ip))
 665                         return -EFAULT;
 666                 return 0;
 667
 668         case EVIOCGRAB:
 669                 if (p)
 670                         return evdev_grab(evdev, client);
 671                 else
 672                         return evdev_ungrab(evdev, client);
 673         }
 674
 675         size = _IOC_SIZE(cmd);
 676
 677         /* Now check variable-length commands */
 678 #define EVIOC_MASK_SIZE(nr)     ((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
 679         switch (EVIOC_MASK_SIZE(cmd)) {
 680
 681         case EVIOCGPROP(0):
 682                 return bits_to_user(dev->propbit, INPUT_PROP_MAX,
 683                                     size, p, compat_mode);
 684
 685         case EVIOCGKEY(0):
 686                 return bits_to_user(dev->key, KEY_MAX, size, p, compat_mode);
 687
 688         case EVIOCGLED(0):
 689                 return bits_to_user(dev->led, LED_MAX, size, p, compat_mode);
 690
 691         case EVIOCGSND(0):
 692                 return bits_to_user(dev->snd, SND_MAX, size, p, compat_mode);
 693
 694         case EVIOCGSW(0):
 695                 return bits_to_user(dev->sw, SW_MAX, size, p, compat_mode);
 696
 697         case EVIOCGNAME(0):
 698                 return str_to_user(dev->name, size, p);
 699
 700         case EVIOCGPHYS(0):
 701                 return str_to_user(dev->phys, size, p);
 702
 703         case EVIOCGUNIQ(0):
 704                 return str_to_user(dev->uniq, size, p);
 705
 706         case EVIOC_MASK_SIZE(EVIOCSFF):
 707                 if (input_ff_effect_from_user(p, size, &effect))
 708                         return -EFAULT;
 709
 710                 error = input_ff_upload(dev, &effect, file);
 711
 712                 if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
 713                         return -EFAULT;
 714
 715                 return error;
 716
 717         case EVIOC_MASK_SIZE(EVIOCGKEYCODE):
 718                 return evdev_handle_get_keycode(dev, p, size);
 719
 720         case EVIOC_MASK_SIZE(EVIOCSKEYCODE):
 721                 return evdev_handle_set_keycode(dev, p, size);
 722         }
 723
 724         /* Multi-number variable-length handlers */
 725         if (_IOC_TYPE(cmd) != 'E')
 726                 return -EINVAL;
 727
 728         if (_IOC_DIR(cmd) == _IOC_READ) {
 729
 730                 if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
 731                         return handle_eviocgbit(dev,
 732                                                 _IOC_NR(cmd) & EV_MAX, size,
 733                                                 p, compat_mode);
 734
 735                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {
 736
 737                         if (!dev->absinfo)
 738                                 return -EINVAL;
 739
 740                         t = _IOC_NR(cmd) & ABS_MAX;
 741                         abs = dev->absinfo[t];
 742
 743                         if (copy_to_user(p, &abs, min_t(size_t,
 744                                         size, sizeof(struct input_absinfo))))
 745                                 return -EFAULT;
 746
 747                         return 0;
 748                 }
 749         }
 750
 751         if (_IOC_DIR(cmd) == _IOC_WRITE) {
 752
 753                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {
 754
 755                         if (!dev->absinfo)
 756                                 return -EINVAL;
 757
 758                         t = _IOC_NR(cmd) & ABS_MAX;
 759
 760                         if (copy_from_user(&abs, p, min_t(size_t,
 761                                         size, sizeof(struct input_absinfo))))
 762                                 return -EFAULT;
 763
 764                         if (size < sizeof(struct input_absinfo))
 765                                 abs.resolution = 0;
 766
 767                         /* We can't change number of reserved MT slots */
 768                         if (t == ABS_MT_SLOT)
 769                                 return -EINVAL;
 770
 771                         /*
 772                          * Take event lock to ensure that we are not
 773                          * changing device parameters in the middle
 774                          * of event.
 775                          */
 776                         spin_lock_irq(&dev->event_lock);
 777                         dev->absinfo[t] = abs;
 778                         spin_unlock_irq(&dev->event_lock);
 779
 780                         return 0;
 781                 }
 782         }
 783
 784         return -EINVAL;
 785 }
 786
 787 static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
 788                                 void __user *p, int compat_mode)
 789 {
 790         struct evdev_client *client = file->private_data;
 791         struct evdev *evdev = client->evdev;
 792         int retval;
 793
 794         retval = mutex_lock_interruptible(&evdev->mutex);
 795         if (retval)
 796                 return retval;
 797
 798         if (!evdev->exist) {
 799                 retval = -ENODEV;
 800                 goto out;
 801         }
 802
 803         retval = evdev_do_ioctl(file, cmd, p, compat_mode);
 804
 805  out:
 806         mutex_unlock(&evdev->mutex);
 807         return retval;
 808 }
 809
 810 static long evdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 811 {
 812         return evdev_ioctl_handler(file, cmd, (void __user *)arg, 0);
 813 }
 814
 815 #ifdef CONFIG_COMPAT
 816 static long evdev_ioctl_compat(struct file *file,
 817                                 unsigned int cmd, unsigned long arg)
 818 {
 819         return evdev_ioctl_handler(file, cmd, compat_ptr(arg), 1);
 820 }
 821 #endif
 822
 823 static const struct file_operations evdev_fops = {
 824         .owner          = THIS_MODULE,
 825         .read           = evdev_read,
 826         .write          = evdev_write,
 827         .poll           = evdev_poll,
 828         .open           = evdev_open,
 829         .release        = evdev_release,
 830         .unlocked_ioctl = evdev_ioctl,
 831 #ifdef CONFIG_COMPAT
 832         .compat_ioctl   = evdev_ioctl_compat,
 833 #endif
 834         .fasync         = evdev_fasync,
 835         .flush          = evdev_flush,
 836         .llseek         = no_llseek,
 837 };
 838
 839 static int evdev_install_chrdev(struct evdev *evdev)
 840 {
 841         /*
 842          * No need to do any locking here as calls to connect and
 843          * disconnect are serialized by the input core
 844          */
 845         evdev_table[evdev->minor] = evdev;
 846         return 0;
 847 }
 848
 849 static void evdev_remove_chrdev(struct evdev *evdev)
 850 {
 851         /*
 852          * Lock evdev table to prevent race with evdev_open()
 853          */
 854         mutex_lock(&evdev_table_mutex);
 855         evdev_table[evdev->minor] = NULL;
 856         mutex_unlock(&evdev_table_mutex);
 857 }
 858
 859 /*
 860  * Mark device non-existent. This disables writes, ioctls and
 861  * prevents new users from opening the device. Already posted
 862  * blocking reads will stay, however new ones will fail.
 863  */
 864 static void evdev_mark_dead(struct evdev *evdev)
 865 {
 866         mutex_lock(&evdev->mutex);
 867         evdev->exist = false;
 868         mutex_unlock(&evdev->mutex);
 869 }
 870
 871 static void evdev_cleanup(struct evdev *evdev)
 872 {
 873         struct input_handle *handle = &evdev->handle;
 874
 875         evdev_mark_dead(evdev);
 876         evdev_hangup(evdev);
 877         evdev_remove_chrdev(evdev);
 878
 879         /* evdev is marked dead so no one else accesses evdev->open */
 880         if (evdev->open) {
 881                 input_flush_device(handle, NULL);
 882                 input_close_device(handle);
 883         }
 884 }
 885
 886 /*
 887  * Create new evdev device. Note that input core serializes calls
 888  * to connect and disconnect so we don't need to lock evdev_table here.
 889  */
 890 static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
 891                          const struct input_device_id *id)
 892 {
 893         struct evdev *evdev;
 894         int minor;
 895         int error;
 896
 897         for (minor = 0; minor < EVDEV_MINORS; minor++)
 898                 if (!evdev_table[minor])
 899                         break;
 900
 901         if (minor == EVDEV_MINORS) {
 902                 pr_err("no more free evdev devices\n");
 903                 return -ENFILE;
 904         }
 905
 906         evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
 907         if (!evdev)
 908                 return -ENOMEM;
 909
 910         INIT_LIST_HEAD(&evdev->client_list);
 911         spin_lock_init(&evdev->client_lock);
 912         mutex_init(&evdev->mutex);
 913         init_waitqueue_head(&evdev->wait);
 914
 915         dev_set_name(&evdev->dev, "event%d", minor);
 916         evdev->exist = true;
 917         evdev->minor = minor;
 918
 919         evdev->handle.dev = input_get_device(dev);
 920         evdev->handle.name = dev_name(&evdev->dev);
 921         evdev->handle.handler = handler;
 922         evdev->handle.private = evdev;
 923
 924         evdev->dev.devt = MKDEV(INPUT_MAJOR, EVDEV_MINOR_BASE + minor);
 925         evdev->dev.class = &input_class;
 926         evdev->dev.parent = &dev->dev;
 927         evdev->dev.release = evdev_free;
 928         device_initialize(&evdev->dev);
 929
 930         error = input_register_handle(&evdev->handle);
 931         if (error)
 932                 goto err_free_evdev;
 933
 934         error = evdev_install_chrdev(evdev);
 935         if (error)
 936                 goto err_unregister_handle;
 937
 938         error = device_add(&evdev->dev);
 939         if (error)
 940                 goto err_cleanup_evdev;
 941
 942         return 0;
 943
 944  err_cleanup_evdev:
 945         evdev_cleanup(evdev);
 946  err_unregister_handle:
 947         input_unregister_handle(&evdev->handle);
 948  err_free_evdev:
 949         put_device(&evdev->dev);
 950         return error;
 951 }
 952
 953 static void evdev_disconnect(struct input_handle *handle)
 954 {
 955         struct evdev *evdev = handle->private;
 956
 957         device_del(&evdev->dev);
 958         evdev_cleanup(evdev);
 959         input_unregister_handle(handle);
 960         put_device(&evdev->dev);
 961 }
 962
 963 static const struct input_device_id evdev_ids[] = {
 964         { .driver_info = 1 },   /* Matches all devices */
 965         { },                    /* Terminating zero entry */
 966 };
 967
 968 MODULE_DEVICE_TABLE(input, evdev_ids);
 969
 970 static struct input_handler evdev_handler = {
 971         .event          = evdev_event,
 972         .connect        = evdev_connect,
 973         .disconnect     = evdev_disconnect,
 974         .fops           = &evdev_fops,
 975         .minor          = EVDEV_MINOR_BASE,
 976         .name           = "evdev",
 977         .id_table       = evdev_ids,
 978 };
 979
 980 static int __init evdev_init(void)
 981 {
 982         return input_register_handler(&evdev_handler);
 983 }
 984
 985 static void __exit evdev_exit(void)
 986 {
 987         input_unregister_handler(&evdev_handler);
 988 }
 989
 990 module_init(evdev_init);
 991 module_exit(evdev_exit);
 992
 993 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
 994 MODULE_DESCRIPTION("Input driver event char devices");
 995 MODULE_LICENSE("GPL");