sound/core/control.c

   1 /*
   2  *  Routines for driver control interface
   3  *  Copyright (c) by Jaroslav Kysela <[email protected]>
   4  *
   5  *
   6  *   This program is free software; you can redistribute it and/or modify
   7  *   it under the terms of the GNU General Public License as published by
   8  *   the Free Software Foundation; either version 2 of the License, or
   9  *   (at your option) any later version.
  10  *
  11  *   This program is distributed in the hope that it will be useful,
  12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *   GNU General Public License for more details.
  15  *
  16  *   You should have received a copy of the GNU General Public License
  17  *   along with this program; if not, write to the Free Software
  18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  19  *
  20  */
  21
  22 #include <linux/threads.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/module.h>
  25 #include <linux/slab.h>
  26 #include <linux/vmalloc.h>
  27 #include <linux/time.h>
  28 #include <linux/mm.h>
  29 #include <linux/sched/signal.h>
  30 #include <sound/core.h>
  31 #include <sound/minors.h>
  32 #include <sound/info.h>
  33 #include <sound/control.h>
  34
  35 /* max number of user-defined controls */
  36 #define MAX_USER_CONTROLS       32
  37 #define MAX_CONTROL_COUNT       1028
  38
  39 struct snd_kctl_ioctl {
  40         struct list_head list;          /* list of all ioctls */
  41         snd_kctl_ioctl_func_t fioctl;
  42 };
  43
  44 static DECLARE_RWSEM(snd_ioctl_rwsem);
  45 static LIST_HEAD(snd_control_ioctls);
  46 #ifdef CONFIG_COMPAT
  47 static LIST_HEAD(snd_control_compat_ioctls);
  48 #endif
  49
  50 static int snd_ctl_open(struct inode *inode, struct file *file)
  51 {
  52         unsigned long flags;
  53         struct snd_card *card;
  54         struct snd_ctl_file *ctl;
  55         int i, err;
  56
  57         err = nonseekable_open(inode, file);
  58         if (err < 0)
  59                 return err;
  60
  61         card = snd_lookup_minor_data(iminor(inode), SNDRV_DEVICE_TYPE_CONTROL);
  62         if (!card) {
  63                 err = -ENODEV;
  64                 goto __error1;
  65         }
  66         err = snd_card_file_add(card, file);
  67         if (err < 0) {
  68                 err = -ENODEV;
  69                 goto __error1;
  70         }
  71         if (!try_module_get(card->module)) {
  72                 err = -EFAULT;
  73                 goto __error2;
  74         }
  75         ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);
  76         if (ctl == NULL) {
  77                 err = -ENOMEM;
  78                 goto __error;
  79         }
  80         INIT_LIST_HEAD(&ctl->events);
  81         init_waitqueue_head(&ctl->change_sleep);
  82         spin_lock_init(&ctl->read_lock);
  83         ctl->card = card;
  84         for (i = 0; i < SND_CTL_SUBDEV_ITEMS; i++)
  85                 ctl->preferred_subdevice[i] = -1;
  86         ctl->pid = get_pid(task_pid(current));
  87         file->private_data = ctl;
  88         write_lock_irqsave(&card->ctl_files_rwlock, flags);
  89         list_add_tail(&ctl->list, &card->ctl_files);
  90         write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
  91         snd_card_unref(card);
  92         return 0;
  93
  94       __error:
  95         module_put(card->module);
  96       __error2:
  97         snd_card_file_remove(card, file);
  98       __error1:
  99         if (card)
 100                 snd_card_unref(card);
 101         return err;
 102 }
 103
 104 static void snd_ctl_empty_read_queue(struct snd_ctl_file * ctl)
 105 {
 106         unsigned long flags;
 107         struct snd_kctl_event *cread;
 108
 109         spin_lock_irqsave(&ctl->read_lock, flags);
 110         while (!list_empty(&ctl->events)) {
 111                 cread = snd_kctl_event(ctl->events.next);
 112                 list_del(&cread->list);
 113                 kfree(cread);
 114         }
 115         spin_unlock_irqrestore(&ctl->read_lock, flags);
 116 }
 117
 118 static int snd_ctl_release(struct inode *inode, struct file *file)
 119 {
 120         unsigned long flags;
 121         struct snd_card *card;
 122         struct snd_ctl_file *ctl;
 123         struct snd_kcontrol *control;
 124         unsigned int idx;
 125
 126         ctl = file->private_data;
 127         file->private_data = NULL;
 128         card = ctl->card;
 129         write_lock_irqsave(&card->ctl_files_rwlock, flags);
 130         list_del(&ctl->list);
 131         write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
 132         down_write(&card->controls_rwsem);
 133         list_for_each_entry(control, &card->controls, list)
 134                 for (idx = 0; idx < control->count; idx++)
 135                         if (control->vd[idx].owner == ctl)
 136                                 control->vd[idx].owner = NULL;
 137         up_write(&card->controls_rwsem);
 138         snd_ctl_empty_read_queue(ctl);
 139         put_pid(ctl->pid);
 140         kfree(ctl);
 141         module_put(card->module);
 142         snd_card_file_remove(card, file);
 143         return 0;
 144 }
 145
 146 /**
 147  * snd_ctl_notify - Send notification to user-space for a control change
 148  * @card: the card to send notification
 149  * @mask: the event mask, SNDRV_CTL_EVENT_*
 150  * @id: the ctl element id to send notification
 151  *
 152  * This function adds an event record with the given id and mask, appends
 153  * to the list and wakes up the user-space for notification.  This can be
 154  * called in the atomic context.
 155  */
 156 void snd_ctl_notify(struct snd_card *card, unsigned int mask,
 157                     struct snd_ctl_elem_id *id)
 158 {
 159         unsigned long flags;
 160         struct snd_ctl_file *ctl;
 161         struct snd_kctl_event *ev;
 162
 163         if (snd_BUG_ON(!card || !id))
 164                 return;
 165         if (card->shutdown)
 166                 return;
 167         read_lock(&card->ctl_files_rwlock);
 168 #if IS_ENABLED(CONFIG_SND_MIXER_OSS)
 169         card->mixer_oss_change_count++;
 170 #endif
 171         list_for_each_entry(ctl, &card->ctl_files, list) {
 172                 if (!ctl->subscribed)
 173                         continue;
 174                 spin_lock_irqsave(&ctl->read_lock, flags);
 175                 list_for_each_entry(ev, &ctl->events, list) {
 176                         if (ev->id.numid == id->numid) {
 177                                 ev->mask |= mask;
 178                                 goto _found;
 179                         }
 180                 }
 181                 ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
 182                 if (ev) {
 183                         ev->id = *id;
 184                         ev->mask = mask;
 185                         list_add_tail(&ev->list, &ctl->events);
 186                 } else {
 187                         dev_err(card->dev, "No memory available to allocate event\n");
 188                 }
 189         _found:
 190                 wake_up(&ctl->change_sleep);
 191                 spin_unlock_irqrestore(&ctl->read_lock, flags);
 192                 kill_fasync(&ctl->fasync, SIGIO, POLL_IN);
 193         }
 194         read_unlock(&card->ctl_files_rwlock);
 195 }
 196 EXPORT_SYMBOL(snd_ctl_notify);
 197
 198 /**
 199  * snd_ctl_new - create a new control instance with some elements
 200  * @kctl: the pointer to store new control instance
 201  * @count: the number of elements in this control
 202  * @access: the default access flags for elements in this control
 203  * @file: given when locking these elements
 204  *
 205  * Allocates a memory object for a new control instance. The instance has
 206  * elements as many as the given number (@count). Each element has given
 207  * access permissions (@access). Each element is locked when @file is given.
 208  *
 209  * Return: 0 on success, error code on failure
 210  */
 211 static int snd_ctl_new(struct snd_kcontrol **kctl, unsigned int count,
 212                        unsigned int access, struct snd_ctl_file *file)
 213 {
 214         unsigned int size;
 215         unsigned int idx;
 216
 217         if (count == 0 || count > MAX_CONTROL_COUNT)
 218                 return -EINVAL;
 219
 220         size  = sizeof(struct snd_kcontrol);
 221         size += sizeof(struct snd_kcontrol_volatile) * count;
 222
 223         *kctl = kzalloc(size, GFP_KERNEL);
 224         if (!*kctl)
 225                 return -ENOMEM;
 226
 227         for (idx = 0; idx < count; idx++) {
 228                 (*kctl)->vd[idx].access = access;
 229                 (*kctl)->vd[idx].owner = file;
 230         }
 231         (*kctl)->count = count;
 232
 233         return 0;
 234 }
 235
 236 /**
 237  * snd_ctl_new1 - create a control instance from the template
 238  * @ncontrol: the initialization record
 239  * @private_data: the private data to set
 240  *
 241  * Allocates a new struct snd_kcontrol instance and initialize from the given
 242  * template.  When the access field of ncontrol is 0, it's assumed as
 243  * READWRITE access. When the count field is 0, it's assumes as one.
 244  *
 245  * Return: The pointer of the newly generated instance, or %NULL on failure.
 246  */
 247 struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new *ncontrol,
 248                                   void *private_data)
 249 {
 250         struct snd_kcontrol *kctl;
 251         unsigned int count;
 252         unsigned int access;
 253         int err;
 254
 255         if (snd_BUG_ON(!ncontrol || !ncontrol->info))
 256                 return NULL;
 257
 258         count = ncontrol->count;
 259         if (count == 0)
 260                 count = 1;
 261
 262         access = ncontrol->access;
 263         if (access == 0)
 264                 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
 265         access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
 266                    SNDRV_CTL_ELEM_ACCESS_VOLATILE |
 267                    SNDRV_CTL_ELEM_ACCESS_INACTIVE |
 268                    SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE |
 269                    SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND |
 270                    SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
 271
 272         err = snd_ctl_new(&kctl, count, access, NULL);
 273         if (err < 0)
 274                 return NULL;
 275
 276         /* The 'numid' member is decided when calling snd_ctl_add(). */
 277         kctl->id.iface = ncontrol->iface;
 278         kctl->id.device = ncontrol->device;
 279         kctl->id.subdevice = ncontrol->subdevice;
 280         if (ncontrol->name) {
 281                 strlcpy(kctl->id.name, ncontrol->name, sizeof(kctl->id.name));
 282                 if (strcmp(ncontrol->name, kctl->id.name) != 0)
 283                         pr_warn("ALSA: Control name '%s' truncated to '%s'\n",
 284                                 ncontrol->name, kctl->id.name);
 285         }
 286         kctl->id.index = ncontrol->index;
 287
 288         kctl->info = ncontrol->info;
 289         kctl->get = ncontrol->get;
 290         kctl->put = ncontrol->put;
 291         kctl->tlv.p = ncontrol->tlv.p;
 292
 293         kctl->private_value = ncontrol->private_value;
 294         kctl->private_data = private_data;
 295
 296         return kctl;
 297 }
 298 EXPORT_SYMBOL(snd_ctl_new1);
 299
 300 /**
 301  * snd_ctl_free_one - release the control instance
 302  * @kcontrol: the control instance
 303  *
 304  * Releases the control instance created via snd_ctl_new()
 305  * or snd_ctl_new1().
 306  * Don't call this after the control was added to the card.
 307  */
 308 void snd_ctl_free_one(struct snd_kcontrol *kcontrol)
 309 {
 310         if (kcontrol) {
 311                 if (kcontrol->private_free)
 312                         kcontrol->private_free(kcontrol);
 313                 kfree(kcontrol);
 314         }
 315 }
 316 EXPORT_SYMBOL(snd_ctl_free_one);
 317
 318 static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
 319                                           unsigned int count)
 320 {
 321         struct snd_kcontrol *kctl;
 322
 323         /* Make sure that the ids assigned to the control do not wrap around */
 324         if (card->last_numid >= UINT_MAX - count)
 325                 card->last_numid = 0;
 326
 327         list_for_each_entry(kctl, &card->controls, list) {
 328                 if (kctl->id.numid < card->last_numid + 1 + count &&
 329                     kctl->id.numid + kctl->count > card->last_numid + 1) {
 330                         card->last_numid = kctl->id.numid + kctl->count - 1;
 331                         return true;
 332                 }
 333         }
 334         return false;
 335 }
 336
 337 static int snd_ctl_find_hole(struct snd_card *card, unsigned int count)
 338 {
 339         unsigned int iter = 100000;
 340
 341         while (snd_ctl_remove_numid_conflict(card, count)) {
 342                 if (--iter == 0) {
 343                         /* this situation is very unlikely */
 344                         dev_err(card->dev, "unable to allocate new control numid\n");
 345                         return -ENOMEM;
 346                 }
 347         }
 348         return 0;
 349 }
 350
 351 enum snd_ctl_add_mode {
 352         CTL_ADD_EXCLUSIVE, CTL_REPLACE, CTL_ADD_ON_REPLACE,
 353 };
 354
 355 /* add/replace a new kcontrol object; call with card->controls_rwsem locked */
 356 static int __snd_ctl_add_replace(struct snd_card *card,
 357                                  struct snd_kcontrol *kcontrol,
 358                                  enum snd_ctl_add_mode mode)
 359 {
 360         struct snd_ctl_elem_id id;
 361         unsigned int idx;
 362         unsigned int count;
 363         struct snd_kcontrol *old;
 364         int err;
 365
 366         id = kcontrol->id;
 367         if (id.index > UINT_MAX - kcontrol->count)
 368                 return -EINVAL;
 369
 370         old = snd_ctl_find_id(card, &id);
 371         if (!old) {
 372                 if (mode == CTL_REPLACE)
 373                         return -EINVAL;
 374         } else {
 375                 if (mode == CTL_ADD_EXCLUSIVE) {
 376                         dev_err(card->dev,
 377                                 "control %i:%i:%i:%s:%i is already present\n",
 378                                 id.iface, id.device, id.subdevice, id.name,
 379                                 id.index);
 380                         return -EBUSY;
 381                 }
 382
 383                 err = snd_ctl_remove(card, old);
 384                 if (err < 0)
 385                         return err;
 386         }
 387
 388         if (snd_ctl_find_hole(card, kcontrol->count) < 0)
 389                 return -ENOMEM;
 390
 391         list_add_tail(&kcontrol->list, &card->controls);
 392         card->controls_count += kcontrol->count;
 393         kcontrol->id.numid = card->last_numid + 1;
 394         card->last_numid += kcontrol->count;
 395
 396         id = kcontrol->id;
 397         count = kcontrol->count;
 398         for (idx = 0; idx < count; idx++, id.index++, id.numid++)
 399                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
 400
 401         return 0;
 402 }
 403
 404 static int snd_ctl_add_replace(struct snd_card *card,
 405                                struct snd_kcontrol *kcontrol,
 406                                enum snd_ctl_add_mode mode)
 407 {
 408         int err = -EINVAL;
 409
 410         if (! kcontrol)
 411                 return err;
 412         if (snd_BUG_ON(!card || !kcontrol->info))
 413                 goto error;
 414
 415         down_write(&card->controls_rwsem);
 416         err = __snd_ctl_add_replace(card, kcontrol, mode);
 417         up_write(&card->controls_rwsem);
 418         if (err < 0)
 419                 goto error;
 420         return 0;
 421
 422  error:
 423         snd_ctl_free_one(kcontrol);
 424         return err;
 425 }
 426
 427 /**
 428  * snd_ctl_add - add the control instance to the card
 429  * @card: the card instance
 430  * @kcontrol: the control instance to add
 431  *
 432  * Adds the control instance created via snd_ctl_new() or
 433  * snd_ctl_new1() to the given card. Assigns also an unique
 434  * numid used for fast search.
 435  *
 436  * It frees automatically the control which cannot be added.
 437  *
 438  * Return: Zero if successful, or a negative error code on failure.
 439  *
 440  */
 441 int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
 442 {
 443         return snd_ctl_add_replace(card, kcontrol, CTL_ADD_EXCLUSIVE);
 444 }
 445 EXPORT_SYMBOL(snd_ctl_add);
 446
 447 /**
 448  * snd_ctl_replace - replace the control instance of the card
 449  * @card: the card instance
 450  * @kcontrol: the control instance to replace
 451  * @add_on_replace: add the control if not already added
 452  *
 453  * Replaces the given control.  If the given control does not exist
 454  * and the add_on_replace flag is set, the control is added.  If the
 455  * control exists, it is destroyed first.
 456  *
 457  * It frees automatically the control which cannot be added or replaced.
 458  *
 459  * Return: Zero if successful, or a negative error code on failure.
 460  */
 461 int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
 462                     bool add_on_replace)
 463 {
 464         return snd_ctl_add_replace(card, kcontrol,
 465                                    add_on_replace ? CTL_ADD_ON_REPLACE : CTL_REPLACE);
 466 }
 467 EXPORT_SYMBOL(snd_ctl_replace);
 468
 469 /**
 470  * snd_ctl_remove - remove the control from the card and release it
 471  * @card: the card instance
 472  * @kcontrol: the control instance to remove
 473  *
 474  * Removes the control from the card and then releases the instance.
 475  * You don't need to call snd_ctl_free_one(). You must be in
 476  * the write lock - down_write(&card->controls_rwsem).
 477  *
 478  * Return: 0 if successful, or a negative error code on failure.
 479  */
 480 int snd_ctl_remove(struct snd_card *card, struct snd_kcontrol *kcontrol)
 481 {
 482         struct snd_ctl_elem_id id;
 483         unsigned int idx;
 484
 485         if (snd_BUG_ON(!card || !kcontrol))
 486                 return -EINVAL;
 487         list_del(&kcontrol->list);
 488         card->controls_count -= kcontrol->count;
 489         id = kcontrol->id;
 490         for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
 491                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_REMOVE, &id);
 492         snd_ctl_free_one(kcontrol);
 493         return 0;
 494 }
 495 EXPORT_SYMBOL(snd_ctl_remove);
 496
 497 /**
 498  * snd_ctl_remove_id - remove the control of the given id and release it
 499  * @card: the card instance
 500  * @id: the control id to remove
 501  *
 502  * Finds the control instance with the given id, removes it from the
 503  * card list and releases it.
 504  *
 505  * Return: 0 if successful, or a negative error code on failure.
 506  */
 507 int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
 508 {
 509         struct snd_kcontrol *kctl;
 510         int ret;
 511
 512         down_write(&card->controls_rwsem);
 513         kctl = snd_ctl_find_id(card, id);
 514         if (kctl == NULL) {
 515                 up_write(&card->controls_rwsem);
 516                 return -ENOENT;
 517         }
 518         ret = snd_ctl_remove(card, kctl);
 519         up_write(&card->controls_rwsem);
 520         return ret;
 521 }
 522 EXPORT_SYMBOL(snd_ctl_remove_id);
 523
 524 /**
 525  * snd_ctl_remove_user_ctl - remove and release the unlocked user control
 526  * @file: active control handle
 527  * @id: the control id to remove
 528  *
 529  * Finds the control instance with the given id, removes it from the
 530  * card list and releases it.
 531  *
 532  * Return: 0 if successful, or a negative error code on failure.
 533  */
 534 static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
 535                                    struct snd_ctl_elem_id *id)
 536 {
 537         struct snd_card *card = file->card;
 538         struct snd_kcontrol *kctl;
 539         int idx, ret;
 540
 541         down_write(&card->controls_rwsem);
 542         kctl = snd_ctl_find_id(card, id);
 543         if (kctl == NULL) {
 544                 ret = -ENOENT;
 545                 goto error;
 546         }
 547         if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER)) {
 548                 ret = -EINVAL;
 549                 goto error;
 550         }
 551         for (idx = 0; idx < kctl->count; idx++)
 552                 if (kctl->vd[idx].owner != NULL && kctl->vd[idx].owner != file) {
 553                         ret = -EBUSY;
 554                         goto error;
 555                 }
 556         ret = snd_ctl_remove(card, kctl);
 557         if (ret < 0)
 558                 goto error;
 559         card->user_ctl_count--;
 560 error:
 561         up_write(&card->controls_rwsem);
 562         return ret;
 563 }
 564
 565 /**
 566  * snd_ctl_activate_id - activate/inactivate the control of the given id
 567  * @card: the card instance
 568  * @id: the control id to activate/inactivate
 569  * @active: non-zero to activate
 570  *
 571  * Finds the control instance with the given id, and activate or
 572  * inactivate the control together with notification, if changed.
 573  * The given ID data is filled with full information.
 574  *
 575  * Return: 0 if unchanged, 1 if changed, or a negative error code on failure.
 576  */
 577 int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
 578                         int active)
 579 {
 580         struct snd_kcontrol *kctl;
 581         struct snd_kcontrol_volatile *vd;
 582         unsigned int index_offset;
 583         int ret;
 584
 585         down_write(&card->controls_rwsem);
 586         kctl = snd_ctl_find_id(card, id);
 587         if (kctl == NULL) {
 588                 ret = -ENOENT;
 589                 goto unlock;
 590         }
 591         index_offset = snd_ctl_get_ioff(kctl, id);
 592         vd = &kctl->vd[index_offset];
 593         ret = 0;
 594         if (active) {
 595                 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
 596                         goto unlock;
 597                 vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
 598         } else {
 599                 if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
 600                         goto unlock;
 601                 vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
 602         }
 603         snd_ctl_build_ioff(id, kctl, index_offset);
 604         ret = 1;
 605  unlock:
 606         up_write(&card->controls_rwsem);
 607         if (ret > 0)
 608                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, id);
 609         return ret;
 610 }
 611 EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
 612
 613 /**
 614  * snd_ctl_rename_id - replace the id of a control on the card
 615  * @card: the card instance
 616  * @src_id: the old id
 617  * @dst_id: the new id
 618  *
 619  * Finds the control with the old id from the card, and replaces the
 620  * id with the new one.
 621  *
 622  * Return: Zero if successful, or a negative error code on failure.
 623  */
 624 int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
 625                       struct snd_ctl_elem_id *dst_id)
 626 {
 627         struct snd_kcontrol *kctl;
 628
 629         down_write(&card->controls_rwsem);
 630         kctl = snd_ctl_find_id(card, src_id);
 631         if (kctl == NULL) {
 632                 up_write(&card->controls_rwsem);
 633                 return -ENOENT;
 634         }
 635         kctl->id = *dst_id;
 636         kctl->id.numid = card->last_numid + 1;
 637         card->last_numid += kctl->count;
 638         up_write(&card->controls_rwsem);
 639         return 0;
 640 }
 641 EXPORT_SYMBOL(snd_ctl_rename_id);
 642
 643 /**
 644  * snd_ctl_find_numid - find the control instance with the given number-id
 645  * @card: the card instance
 646  * @numid: the number-id to search
 647  *
 648  * Finds the control instance with the given number-id from the card.
 649  *
 650  * The caller must down card->controls_rwsem before calling this function
 651  * (if the race condition can happen).
 652  *
 653  * Return: The pointer of the instance if found, or %NULL if not.
 654  *
 655  */
 656 struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card, unsigned int numid)
 657 {
 658         struct snd_kcontrol *kctl;
 659
 660         if (snd_BUG_ON(!card || !numid))
 661                 return NULL;
 662         list_for_each_entry(kctl, &card->controls, list) {
 663                 if (kctl->id.numid <= numid && kctl->id.numid + kctl->count > numid)
 664                         return kctl;
 665         }
 666         return NULL;
 667 }
 668 EXPORT_SYMBOL(snd_ctl_find_numid);
 669
 670 /**
 671  * snd_ctl_find_id - find the control instance with the given id
 672  * @card: the card instance
 673  * @id: the id to search
 674  *
 675  * Finds the control instance with the given id from the card.
 676  *
 677  * The caller must down card->controls_rwsem before calling this function
 678  * (if the race condition can happen).
 679  *
 680  * Return: The pointer of the instance if found, or %NULL if not.
 681  *
 682  */
 683 struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
 684                                      struct snd_ctl_elem_id *id)
 685 {
 686         struct snd_kcontrol *kctl;
 687
 688         if (snd_BUG_ON(!card || !id))
 689                 return NULL;
 690         if (id->numid != 0)
 691                 return snd_ctl_find_numid(card, id->numid);
 692         list_for_each_entry(kctl, &card->controls, list) {
 693                 if (kctl->id.iface != id->iface)
 694                         continue;
 695                 if (kctl->id.device != id->device)
 696                         continue;
 697                 if (kctl->id.subdevice != id->subdevice)
 698                         continue;
 699                 if (strncmp(kctl->id.name, id->name, sizeof(kctl->id.name)))
 700                         continue;
 701                 if (kctl->id.index > id->index)
 702                         continue;
 703                 if (kctl->id.index + kctl->count <= id->index)
 704                         continue;
 705                 return kctl;
 706         }
 707         return NULL;
 708 }
 709 EXPORT_SYMBOL(snd_ctl_find_id);
 710
 711 static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,
 712                              unsigned int cmd, void __user *arg)
 713 {
 714         struct snd_ctl_card_info *info;
 715
 716         info = kzalloc(sizeof(*info), GFP_KERNEL);
 717         if (! info)
 718                 return -ENOMEM;
 719         down_read(&snd_ioctl_rwsem);
 720         info->card = card->number;
 721         strlcpy(info->id, card->id, sizeof(info->id));
 722         strlcpy(info->driver, card->driver, sizeof(info->driver));
 723         strlcpy(info->name, card->shortname, sizeof(info->name));
 724         strlcpy(info->longname, card->longname, sizeof(info->longname));
 725         strlcpy(info->mixername, card->mixername, sizeof(info->mixername));
 726         strlcpy(info->components, card->components, sizeof(info->components));
 727         up_read(&snd_ioctl_rwsem);
 728         if (copy_to_user(arg, info, sizeof(struct snd_ctl_card_info))) {
 729                 kfree(info);
 730                 return -EFAULT;
 731         }
 732         kfree(info);
 733         return 0;
 734 }
 735
 736 static int snd_ctl_elem_list(struct snd_card *card,
 737                              struct snd_ctl_elem_list __user *_list)
 738 {
 739         struct snd_ctl_elem_list list;
 740         struct snd_kcontrol *kctl;
 741         struct snd_ctl_elem_id id;
 742         unsigned int offset, space, jidx;
 743         int err = 0;
 744
 745         if (copy_from_user(&list, _list, sizeof(list)))
 746                 return -EFAULT;
 747         offset = list.offset;
 748         space = list.space;
 749
 750         down_read(&card->controls_rwsem);
 751         list.count = card->controls_count;
 752         list.used = 0;
 753         if (space > 0) {
 754                 list_for_each_entry(kctl, &card->controls, list) {
 755                         if (offset >= kctl->count) {
 756                                 offset -= kctl->count;
 757                                 continue;
 758                         }
 759                         for (jidx = offset; jidx < kctl->count; jidx++) {
 760                                 snd_ctl_build_ioff(&id, kctl, jidx);
 761                                 if (copy_to_user(list.pids + list.used, &id,
 762                                                  sizeof(id))) {
 763                                         err = -EFAULT;
 764                                         goto out;
 765                                 }
 766                                 list.used++;
 767                                 if (!--space)
 768                                         goto out;
 769                         }
 770                         offset = 0;
 771                 }
 772         }
 773  out:
 774         up_read(&card->controls_rwsem);
 775         if (!err && copy_to_user(_list, &list, sizeof(list)))
 776                 err = -EFAULT;
 777         return err;
 778 }
 779
 780 static bool validate_element_member_dimension(struct snd_ctl_elem_info *info)
 781 {
 782         unsigned int members;
 783         unsigned int i;
 784
 785         if (info->dimen.d[0] == 0)
 786                 return true;
 787
 788         members = 1;
 789         for (i = 0; i < ARRAY_SIZE(info->dimen.d); ++i) {
 790                 if (info->dimen.d[i] == 0)
 791                         break;
 792                 members *= info->dimen.d[i];
 793
 794                 /*
 795                  * info->count should be validated in advance, to guarantee
 796                  * calculation soundness.
 797                  */
 798                 if (members > info->count)
 799                         return false;
 800         }
 801
 802         for (++i; i < ARRAY_SIZE(info->dimen.d); ++i) {
 803                 if (info->dimen.d[i] > 0)
 804                         return false;
 805         }
 806
 807         return members == info->count;
 808 }
 809
 810 static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
 811                              struct snd_ctl_elem_info *info)
 812 {
 813         struct snd_card *card = ctl->card;
 814         struct snd_kcontrol *kctl;
 815         struct snd_kcontrol_volatile *vd;
 816         unsigned int index_offset;
 817         int result;
 818
 819         down_read(&card->controls_rwsem);
 820         kctl = snd_ctl_find_id(card, &info->id);
 821         if (kctl == NULL) {
 822                 up_read(&card->controls_rwsem);
 823                 return -ENOENT;
 824         }
 825 #ifdef CONFIG_SND_DEBUG
 826         info->access = 0;
 827 #endif
 828         result = kctl->info(kctl, info);
 829         if (result >= 0) {
 830                 snd_BUG_ON(info->access);
 831                 index_offset = snd_ctl_get_ioff(kctl, &info->id);
 832                 vd = &kctl->vd[index_offset];
 833                 snd_ctl_build_ioff(&info->id, kctl, index_offset);
 834                 info->access = vd->access;
 835                 if (vd->owner) {
 836                         info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
 837                         if (vd->owner == ctl)
 838                                 info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
 839                         info->owner = pid_vnr(vd->owner->pid);
 840                 } else {
 841                         info->owner = -1;
 842                 }
 843         }
 844         up_read(&card->controls_rwsem);
 845         return result;
 846 }
 847
 848 static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
 849                                   struct snd_ctl_elem_info __user *_info)
 850 {
 851         struct snd_ctl_elem_info info;
 852         int result;
 853
 854         if (copy_from_user(&info, _info, sizeof(info)))
 855                 return -EFAULT;
 856         result = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);
 857         if (result < 0)
 858                 return result;
 859         result = snd_ctl_elem_info(ctl, &info);
 860         if (result < 0)
 861                 return result;
 862         if (copy_to_user(_info, &info, sizeof(info)))
 863                 return -EFAULT;
 864         return result;
 865 }
 866
 867 static int snd_ctl_elem_read(struct snd_card *card,
 868                              struct snd_ctl_elem_value *control)
 869 {
 870         struct snd_kcontrol *kctl;
 871         struct snd_kcontrol_volatile *vd;
 872         unsigned int index_offset;
 873
 874         kctl = snd_ctl_find_id(card, &control->id);
 875         if (kctl == NULL)
 876                 return -ENOENT;
 877
 878         index_offset = snd_ctl_get_ioff(kctl, &control->id);
 879         vd = &kctl->vd[index_offset];
 880         if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_READ) || kctl->get == NULL)
 881                 return -EPERM;
 882
 883         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 884         return kctl->get(kctl, control);
 885 }
 886
 887 static int snd_ctl_elem_read_user(struct snd_card *card,
 888                                   struct snd_ctl_elem_value __user *_control)
 889 {
 890         struct snd_ctl_elem_value *control;
 891         int result;
 892
 893         control = memdup_user(_control, sizeof(*control));
 894         if (IS_ERR(control))
 895                 return PTR_ERR(control);
 896
 897         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 898         if (result < 0)
 899                 goto error;
 900
 901         down_read(&card->controls_rwsem);
 902         result = snd_ctl_elem_read(card, control);
 903         up_read(&card->controls_rwsem);
 904         if (result < 0)
 905                 goto error;
 906
 907         if (copy_to_user(_control, control, sizeof(*control)))
 908                 result = -EFAULT;
 909  error:
 910         kfree(control);
 911         return result;
 912 }
 913
 914 static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
 915                               struct snd_ctl_elem_value *control)
 916 {
 917         struct snd_kcontrol *kctl;
 918         struct snd_kcontrol_volatile *vd;
 919         unsigned int index_offset;
 920         int result;
 921
 922         kctl = snd_ctl_find_id(card, &control->id);
 923         if (kctl == NULL)
 924                 return -ENOENT;
 925
 926         index_offset = snd_ctl_get_ioff(kctl, &control->id);
 927         vd = &kctl->vd[index_offset];
 928         if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_WRITE) || kctl->put == NULL ||
 929             (file && vd->owner && vd->owner != file)) {
 930                 return -EPERM;
 931         }
 932
 933         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 934         result = kctl->put(kctl, control);
 935         if (result < 0)
 936                 return result;
 937
 938         if (result > 0) {
 939                 struct snd_ctl_elem_id id = control->id;
 940                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, &id);
 941         }
 942
 943         return 0;
 944 }
 945
 946 static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
 947                                    struct snd_ctl_elem_value __user *_control)
 948 {
 949         struct snd_ctl_elem_value *control;
 950         struct snd_card *card;
 951         int result;
 952
 953         control = memdup_user(_control, sizeof(*control));
 954         if (IS_ERR(control))
 955                 return PTR_ERR(control);
 956
 957         card = file->card;
 958         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 959         if (result < 0)
 960                 goto error;
 961
 962         down_write(&card->controls_rwsem);
 963         result = snd_ctl_elem_write(card, file, control);
 964         up_write(&card->controls_rwsem);
 965         if (result < 0)
 966                 goto error;
 967
 968         if (copy_to_user(_control, control, sizeof(*control)))
 969                 result = -EFAULT;
 970  error:
 971         kfree(control);
 972         return result;
 973 }
 974
 975 static int snd_ctl_elem_lock(struct snd_ctl_file *file,
 976                              struct snd_ctl_elem_id __user *_id)
 977 {
 978         struct snd_card *card = file->card;
 979         struct snd_ctl_elem_id id;
 980         struct snd_kcontrol *kctl;
 981         struct snd_kcontrol_volatile *vd;
 982         int result;
 983
 984         if (copy_from_user(&id, _id, sizeof(id)))
 985                 return -EFAULT;
 986         down_write(&card->controls_rwsem);
 987         kctl = snd_ctl_find_id(card, &id);
 988         if (kctl == NULL) {
 989                 result = -ENOENT;
 990         } else {
 991                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
 992                 if (vd->owner != NULL)
 993                         result = -EBUSY;
 994                 else {
 995                         vd->owner = file;
 996                         result = 0;
 997                 }
 998         }
 999         up_write(&card->controls_rwsem);
1000         return result;
1001 }
1002
1003 static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
1004                                struct snd_ctl_elem_id __user *_id)
1005 {
1006         struct snd_card *card = file->card;
1007         struct snd_ctl_elem_id id;
1008         struct snd_kcontrol *kctl;
1009         struct snd_kcontrol_volatile *vd;
1010         int result;
1011
1012         if (copy_from_user(&id, _id, sizeof(id)))
1013                 return -EFAULT;
1014         down_write(&card->controls_rwsem);
1015         kctl = snd_ctl_find_id(card, &id);
1016         if (kctl == NULL) {
1017                 result = -ENOENT;
1018         } else {
1019                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1020                 if (vd->owner == NULL)
1021                         result = -EINVAL;
1022                 else if (vd->owner != file)
1023                         result = -EPERM;
1024                 else {
1025                         vd->owner = NULL;
1026                         result = 0;
1027                 }
1028         }
1029         up_write(&card->controls_rwsem);
1030         return result;
1031 }
1032
1033 struct user_element {
1034         struct snd_ctl_elem_info info;
1035         struct snd_card *card;
1036         char *elem_data;                /* element data */
1037         unsigned long elem_data_size;   /* size of element data in bytes */
1038         void *tlv_data;                 /* TLV data */
1039         unsigned long tlv_data_size;    /* TLV data size */
1040         void *priv_data;                /* private data (like strings for enumerated type) */
1041 };
1042
1043 static int snd_ctl_elem_user_info(struct snd_kcontrol *kcontrol,
1044                                   struct snd_ctl_elem_info *uinfo)
1045 {
1046         struct user_element *ue = kcontrol->private_data;
1047         unsigned int offset;
1048
1049         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1050         *uinfo = ue->info;
1051         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1052
1053         return 0;
1054 }
1055
1056 static int snd_ctl_elem_user_enum_info(struct snd_kcontrol *kcontrol,
1057                                        struct snd_ctl_elem_info *uinfo)
1058 {
1059         struct user_element *ue = kcontrol->private_data;
1060         const char *names;
1061         unsigned int item;
1062         unsigned int offset;
1063
1064         item = uinfo->value.enumerated.item;
1065
1066         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1067         *uinfo = ue->info;
1068         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1069
1070         item = min(item, uinfo->value.enumerated.items - 1);
1071         uinfo->value.enumerated.item = item;
1072
1073         names = ue->priv_data;
1074         for (; item > 0; --item)
1075                 names += strlen(names) + 1;
1076         strcpy(uinfo->value.enumerated.name, names);
1077
1078         return 0;
1079 }
1080
1081 static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
1082                                  struct snd_ctl_elem_value *ucontrol)
1083 {
1084         struct user_element *ue = kcontrol->private_data;
1085         unsigned int size = ue->elem_data_size;
1086         char *src = ue->elem_data +
1087                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1088
1089         memcpy(&ucontrol->value, src, size);
1090         return 0;
1091 }
1092
1093 static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
1094                                  struct snd_ctl_elem_value *ucontrol)
1095 {
1096         int change;
1097         struct user_element *ue = kcontrol->private_data;
1098         unsigned int size = ue->elem_data_size;
1099         char *dst = ue->elem_data +
1100                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1101
1102         change = memcmp(&ucontrol->value, dst, size) != 0;
1103         if (change)
1104                 memcpy(dst, &ucontrol->value, size);
1105         return change;
1106 }
1107
1108 static int replace_user_tlv(struct snd_kcontrol *kctl, unsigned int __user *buf,
1109                             unsigned int size)
1110 {
1111         struct user_element *ue = kctl->private_data;
1112         unsigned int *container;
1113         struct snd_ctl_elem_id id;
1114         unsigned int mask = 0;
1115         int i;
1116         int change;
1117
1118         if (size > 1024 * 128)  /* sane value */
1119                 return -EINVAL;
1120
1121         container = vmemdup_user(buf, size);
1122         if (IS_ERR(container))
1123                 return PTR_ERR(container);
1124
1125         change = ue->tlv_data_size != size;
1126         if (!change)
1127                 change = memcmp(ue->tlv_data, container, size) != 0;
1128         if (!change) {
1129                 kvfree(container);
1130                 return 0;
1131         }
1132
1133         if (ue->tlv_data == NULL) {
1134                 /* Now TLV data is available. */
1135                 for (i = 0; i < kctl->count; ++i)
1136                         kctl->vd[i].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
1137                 mask = SNDRV_CTL_EVENT_MASK_INFO;
1138         }
1139
1140         kvfree(ue->tlv_data);
1141         ue->tlv_data = container;
1142         ue->tlv_data_size = size;
1143
1144         mask |= SNDRV_CTL_EVENT_MASK_TLV;
1145         for (i = 0; i < kctl->count; ++i) {
1146                 snd_ctl_build_ioff(&id, kctl, i);
1147                 snd_ctl_notify(ue->card, mask, &id);
1148         }
1149
1150         return change;
1151 }
1152
1153 static int read_user_tlv(struct snd_kcontrol *kctl, unsigned int __user *buf,
1154                          unsigned int size)
1155 {
1156         struct user_element *ue = kctl->private_data;
1157
1158         if (ue->tlv_data_size == 0 || ue->tlv_data == NULL)
1159                 return -ENXIO;
1160
1161         if (size < ue->tlv_data_size)
1162                 return -ENOSPC;
1163
1164         if (copy_to_user(buf, ue->tlv_data, ue->tlv_data_size))
1165                 return -EFAULT;
1166
1167         return 0;
1168 }
1169
1170 static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kctl, int op_flag,
1171                                  unsigned int size, unsigned int __user *buf)
1172 {
1173         if (op_flag == SNDRV_CTL_TLV_OP_WRITE)
1174                 return replace_user_tlv(kctl, buf, size);
1175         else
1176                 return read_user_tlv(kctl, buf, size);
1177 }
1178
1179 static int snd_ctl_elem_init_enum_names(struct user_element *ue)
1180 {
1181         char *names, *p;
1182         size_t buf_len, name_len;
1183         unsigned int i;
1184         const uintptr_t user_ptrval = ue->info.value.enumerated.names_ptr;
1185
1186         if (ue->info.value.enumerated.names_length > 64 * 1024)
1187                 return -EINVAL;
1188
1189         names = vmemdup_user((const void __user *)user_ptrval,
1190                 ue->info.value.enumerated.names_length);
1191         if (IS_ERR(names))
1192                 return PTR_ERR(names);
1193
1194         /* check that there are enough valid names */
1195         buf_len = ue->info.value.enumerated.names_length;
1196         p = names;
1197         for (i = 0; i < ue->info.value.enumerated.items; ++i) {
1198                 name_len = strnlen(p, buf_len);
1199                 if (name_len == 0 || name_len >= 64 || name_len == buf_len) {
1200                         kvfree(names);
1201                         return -EINVAL;
1202                 }
1203                 p += name_len + 1;
1204                 buf_len -= name_len + 1;
1205         }
1206
1207         ue->priv_data = names;
1208         ue->info.value.enumerated.names_ptr = 0;
1209
1210         return 0;
1211 }
1212
1213 static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)
1214 {
1215         struct user_element *ue = kcontrol->private_data;
1216
1217         kvfree(ue->tlv_data);
1218         kvfree(ue->priv_data);
1219         kfree(ue);
1220 }
1221
1222 static int snd_ctl_elem_add(struct snd_ctl_file *file,
1223                             struct snd_ctl_elem_info *info, int replace)
1224 {
1225         /* The capacity of struct snd_ctl_elem_value.value.*/
1226         static const unsigned int value_sizes[] = {
1227                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = sizeof(long),
1228                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = sizeof(long),
1229                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = sizeof(unsigned int),
1230                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = sizeof(unsigned char),
1231                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = sizeof(struct snd_aes_iec958),
1232                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = sizeof(long long),
1233         };
1234         static const unsigned int max_value_counts[] = {
1235                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = 128,
1236                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = 128,
1237                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = 128,
1238                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = 512,
1239                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = 1,
1240                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = 64,
1241         };
1242         struct snd_card *card = file->card;
1243         struct snd_kcontrol *kctl;
1244         unsigned int count;
1245         unsigned int access;
1246         long private_size;
1247         struct user_element *ue;
1248         unsigned int offset;
1249         int err;
1250
1251         if (!*info->id.name)
1252                 return -EINVAL;
1253         if (strnlen(info->id.name, sizeof(info->id.name)) >= sizeof(info->id.name))
1254                 return -EINVAL;
1255
1256         /* Delete a control to replace them if needed. */
1257         if (replace) {
1258                 info->id.numid = 0;
1259                 err = snd_ctl_remove_user_ctl(file, &info->id);
1260                 if (err)
1261                         return err;
1262         }
1263
1264         /*
1265          * The number of userspace controls are counted control by control,
1266          * not element by element.
1267          */
1268         if (card->user_ctl_count + 1 > MAX_USER_CONTROLS)
1269                 return -ENOMEM;
1270
1271         /* Check the number of elements for this userspace control. */
1272         count = info->owner;
1273         if (count == 0)
1274                 count = 1;
1275
1276         /* Arrange access permissions if needed. */
1277         access = info->access;
1278         if (access == 0)
1279                 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
1280         access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
1281                    SNDRV_CTL_ELEM_ACCESS_INACTIVE |
1282                    SNDRV_CTL_ELEM_ACCESS_TLV_WRITE);
1283
1284         /* In initial state, nothing is available as TLV container. */
1285         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE)
1286                 access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
1287         access |= SNDRV_CTL_ELEM_ACCESS_USER;
1288
1289         /*
1290          * Check information and calculate the size of data specific to
1291          * this userspace control.
1292          */
1293         if (info->type < SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
1294             info->type > SNDRV_CTL_ELEM_TYPE_INTEGER64)
1295                 return -EINVAL;
1296         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED &&
1297             info->value.enumerated.items == 0)
1298                 return -EINVAL;
1299         if (info->count < 1 ||
1300             info->count > max_value_counts[info->type])
1301                 return -EINVAL;
1302         if (!validate_element_member_dimension(info))
1303                 return -EINVAL;
1304         private_size = value_sizes[info->type] * info->count;
1305
1306         /*
1307          * Keep memory object for this userspace control. After passing this
1308          * code block, the instance should be freed by snd_ctl_free_one().
1309          *
1310          * Note that these elements in this control are locked.
1311          */
1312         err = snd_ctl_new(&kctl, count, access, file);
1313         if (err < 0)
1314                 return err;
1315         memcpy(&kctl->id, &info->id, sizeof(kctl->id));
1316         kctl->private_data = kzalloc(sizeof(struct user_element) + private_size * count,
1317                                      GFP_KERNEL);
1318         if (kctl->private_data == NULL) {
1319                 kfree(kctl);
1320                 return -ENOMEM;
1321         }
1322         kctl->private_free = snd_ctl_elem_user_free;
1323
1324         /* Set private data for this userspace control. */
1325         ue = (struct user_element *)kctl->private_data;
1326         ue->card = card;
1327         ue->info = *info;
1328         ue->info.access = 0;
1329         ue->elem_data = (char *)ue + sizeof(*ue);
1330         ue->elem_data_size = private_size;
1331         if (ue->info.type == SNDRV_CTL_ELEM_TYPE_ENUMERATED) {
1332                 err = snd_ctl_elem_init_enum_names(ue);
1333                 if (err < 0) {
1334                         snd_ctl_free_one(kctl);
1335                         return err;
1336                 }
1337         }
1338
1339         /* Set callback functions. */
1340         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
1341                 kctl->info = snd_ctl_elem_user_enum_info;
1342         else
1343                 kctl->info = snd_ctl_elem_user_info;
1344         if (access & SNDRV_CTL_ELEM_ACCESS_READ)
1345                 kctl->get = snd_ctl_elem_user_get;
1346         if (access & SNDRV_CTL_ELEM_ACCESS_WRITE)
1347                 kctl->put = snd_ctl_elem_user_put;
1348         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE)
1349                 kctl->tlv.c = snd_ctl_elem_user_tlv;
1350
1351         /* This function manage to free the instance on failure. */
1352         down_write(&card->controls_rwsem);
1353         err = __snd_ctl_add_replace(card, kctl, CTL_ADD_EXCLUSIVE);
1354         if (err < 0) {
1355                 snd_ctl_free_one(kctl);
1356                 goto unlock;
1357         }
1358         offset = snd_ctl_get_ioff(kctl, &info->id);
1359         snd_ctl_build_ioff(&info->id, kctl, offset);
1360         /*
1361          * Here we cannot fill any field for the number of elements added by
1362          * this operation because there're no specific fields. The usage of
1363          * 'owner' field for this purpose may cause any bugs to userspace
1364          * applications because the field originally means PID of a process
1365          * which locks the element.
1366          */
1367
1368         card->user_ctl_count++;
1369
1370  unlock:
1371         up_write(&card->controls_rwsem);
1372         return 0;
1373 }
1374
1375 static int snd_ctl_elem_add_user(struct snd_ctl_file *file,
1376                                  struct snd_ctl_elem_info __user *_info, int replace)
1377 {
1378         struct snd_ctl_elem_info info;
1379         int err;
1380
1381         if (copy_from_user(&info, _info, sizeof(info)))
1382                 return -EFAULT;
1383         err = snd_ctl_elem_add(file, &info, replace);
1384         if (err < 0)
1385                 return err;
1386         if (copy_to_user(_info, &info, sizeof(info))) {
1387                 snd_ctl_remove_user_ctl(file, &info.id);
1388                 return -EFAULT;
1389         }
1390
1391         return 0;
1392 }
1393
1394 static int snd_ctl_elem_remove(struct snd_ctl_file *file,
1395                                struct snd_ctl_elem_id __user *_id)
1396 {
1397         struct snd_ctl_elem_id id;
1398
1399         if (copy_from_user(&id, _id, sizeof(id)))
1400                 return -EFAULT;
1401         return snd_ctl_remove_user_ctl(file, &id);
1402 }
1403
1404 static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
1405 {
1406         int subscribe;
1407         if (get_user(subscribe, ptr))
1408                 return -EFAULT;
1409         if (subscribe < 0) {
1410                 subscribe = file->subscribed;
1411                 if (put_user(subscribe, ptr))
1412                         return -EFAULT;
1413                 return 0;
1414         }
1415         if (subscribe) {
1416                 file->subscribed = 1;
1417                 return 0;
1418         } else if (file->subscribed) {
1419                 snd_ctl_empty_read_queue(file);
1420                 file->subscribed = 0;
1421         }
1422         return 0;
1423 }
1424
1425 static int call_tlv_handler(struct snd_ctl_file *file, int op_flag,
1426                             struct snd_kcontrol *kctl,
1427                             struct snd_ctl_elem_id *id,
1428                             unsigned int __user *buf, unsigned int size)
1429 {
1430         static const struct {
1431                 int op;
1432                 int perm;
1433         } pairs[] = {
1434                 {SNDRV_CTL_TLV_OP_READ,  SNDRV_CTL_ELEM_ACCESS_TLV_READ},
1435                 {SNDRV_CTL_TLV_OP_WRITE, SNDRV_CTL_ELEM_ACCESS_TLV_WRITE},
1436                 {SNDRV_CTL_TLV_OP_CMD,   SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND},
1437         };
1438         struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)];
1439         int i;
1440
1441         /* Check support of the request for this element. */
1442         for (i = 0; i < ARRAY_SIZE(pairs); ++i) {
1443                 if (op_flag == pairs[i].op && (vd->access & pairs[i].perm))
1444                         break;
1445         }
1446         if (i == ARRAY_SIZE(pairs))
1447                 return -ENXIO;
1448
1449         if (kctl->tlv.c == NULL)
1450                 return -ENXIO;
1451
1452         /* When locked, this is unavailable. */
1453         if (vd->owner != NULL && vd->owner != file)
1454                 return -EPERM;
1455
1456         return kctl->tlv.c(kctl, op_flag, size, buf);
1457 }
1458
1459 static int read_tlv_buf(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id,
1460                         unsigned int __user *buf, unsigned int size)
1461 {
1462         struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)];
1463         unsigned int len;
1464
1465         if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ))
1466                 return -ENXIO;
1467
1468         if (kctl->tlv.p == NULL)
1469                 return -ENXIO;
1470
1471         len = sizeof(unsigned int) * 2 + kctl->tlv.p[1];
1472         if (size < len)
1473                 return -ENOMEM;
1474
1475         if (copy_to_user(buf, kctl->tlv.p, len))
1476                 return -EFAULT;
1477
1478         return 0;
1479 }
1480
1481 static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
1482                              struct snd_ctl_tlv __user *buf,
1483                              int op_flag)
1484 {
1485         struct snd_ctl_tlv header;
1486         unsigned int __user *container;
1487         unsigned int container_size;
1488         struct snd_kcontrol *kctl;
1489         struct snd_ctl_elem_id id;
1490         struct snd_kcontrol_volatile *vd;
1491
1492         if (copy_from_user(&header, buf, sizeof(header)))
1493                 return -EFAULT;
1494
1495         /* In design of control core, numerical ID starts at 1. */
1496         if (header.numid == 0)
1497                 return -EINVAL;
1498
1499         /* At least, container should include type and length fields.  */
1500         if (header.length < sizeof(unsigned int) * 2)
1501                 return -EINVAL;
1502         container_size = header.length;
1503         container = buf->tlv;
1504
1505         kctl = snd_ctl_find_numid(file->card, header.numid);
1506         if (kctl == NULL)
1507                 return -ENOENT;
1508
1509         /* Calculate index of the element in this set. */
1510         id = kctl->id;
1511         snd_ctl_build_ioff(&id, kctl, header.numid - id.numid);
1512         vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1513
1514         if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
1515                 return call_tlv_handler(file, op_flag, kctl, &id, container,
1516                                         container_size);
1517         } else {
1518                 if (op_flag == SNDRV_CTL_TLV_OP_READ) {
1519                         return read_tlv_buf(kctl, &id, container,
1520                                             container_size);
1521                 }
1522         }
1523
1524         /* Not supported. */
1525         return -ENXIO;
1526 }
1527
1528 static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1529 {
1530         struct snd_ctl_file *ctl;
1531         struct snd_card *card;
1532         struct snd_kctl_ioctl *p;
1533         void __user *argp = (void __user *)arg;
1534         int __user *ip = argp;
1535         int err;
1536
1537         ctl = file->private_data;
1538         card = ctl->card;
1539         if (snd_BUG_ON(!card))
1540                 return -ENXIO;
1541         switch (cmd) {
1542         case SNDRV_CTL_IOCTL_PVERSION:
1543                 return put_user(SNDRV_CTL_VERSION, ip) ? -EFAULT : 0;
1544         case SNDRV_CTL_IOCTL_CARD_INFO:
1545                 return snd_ctl_card_info(card, ctl, cmd, argp);
1546         case SNDRV_CTL_IOCTL_ELEM_LIST:
1547                 return snd_ctl_elem_list(card, argp);
1548         case SNDRV_CTL_IOCTL_ELEM_INFO:
1549                 return snd_ctl_elem_info_user(ctl, argp);
1550         case SNDRV_CTL_IOCTL_ELEM_READ:
1551                 return snd_ctl_elem_read_user(card, argp);
1552         case SNDRV_CTL_IOCTL_ELEM_WRITE:
1553                 return snd_ctl_elem_write_user(ctl, argp);
1554         case SNDRV_CTL_IOCTL_ELEM_LOCK:
1555                 return snd_ctl_elem_lock(ctl, argp);
1556         case SNDRV_CTL_IOCTL_ELEM_UNLOCK:
1557                 return snd_ctl_elem_unlock(ctl, argp);
1558         case SNDRV_CTL_IOCTL_ELEM_ADD:
1559                 return snd_ctl_elem_add_user(ctl, argp, 0);
1560         case SNDRV_CTL_IOCTL_ELEM_REPLACE:
1561                 return snd_ctl_elem_add_user(ctl, argp, 1);
1562         case SNDRV_CTL_IOCTL_ELEM_REMOVE:
1563                 return snd_ctl_elem_remove(ctl, argp);
1564         case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
1565                 return snd_ctl_subscribe_events(ctl, ip);
1566         case SNDRV_CTL_IOCTL_TLV_READ:
1567                 down_read(&ctl->card->controls_rwsem);
1568                 err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_READ);
1569                 up_read(&ctl->card->controls_rwsem);
1570                 return err;
1571         case SNDRV_CTL_IOCTL_TLV_WRITE:
1572                 down_write(&ctl->card->controls_rwsem);
1573                 err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_WRITE);
1574                 up_write(&ctl->card->controls_rwsem);
1575                 return err;
1576         case SNDRV_CTL_IOCTL_TLV_COMMAND:
1577                 down_write(&ctl->card->controls_rwsem);
1578                 err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_CMD);
1579                 up_write(&ctl->card->controls_rwsem);
1580                 return err;
1581         case SNDRV_CTL_IOCTL_POWER:
1582                 return -ENOPROTOOPT;
1583         case SNDRV_CTL_IOCTL_POWER_STATE:
1584 #ifdef CONFIG_PM
1585                 return put_user(card->power_state, ip) ? -EFAULT : 0;
1586 #else
1587                 return put_user(SNDRV_CTL_POWER_D0, ip) ? -EFAULT : 0;
1588 #endif
1589         }
1590         down_read(&snd_ioctl_rwsem);
1591         list_for_each_entry(p, &snd_control_ioctls, list) {
1592                 err = p->fioctl(card, ctl, cmd, arg);
1593                 if (err != -ENOIOCTLCMD) {
1594                         up_read(&snd_ioctl_rwsem);
1595                         return err;
1596                 }
1597         }
1598         up_read(&snd_ioctl_rwsem);
1599         dev_dbg(card->dev, "unknown ioctl = 0x%x\n", cmd);
1600         return -ENOTTY;
1601 }
1602
1603 static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
1604                             size_t count, loff_t * offset)
1605 {
1606         struct snd_ctl_file *ctl;
1607         int err = 0;
1608         ssize_t result = 0;
1609
1610         ctl = file->private_data;
1611         if (snd_BUG_ON(!ctl || !ctl->card))
1612                 return -ENXIO;
1613         if (!ctl->subscribed)
1614                 return -EBADFD;
1615         if (count < sizeof(struct snd_ctl_event))
1616                 return -EINVAL;
1617         spin_lock_irq(&ctl->read_lock);
1618         while (count >= sizeof(struct snd_ctl_event)) {
1619                 struct snd_ctl_event ev;
1620                 struct snd_kctl_event *kev;
1621                 while (list_empty(&ctl->events)) {
1622                         wait_queue_entry_t wait;
1623                         if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
1624                                 err = -EAGAIN;
1625                                 goto __end_lock;
1626                         }
1627                         init_waitqueue_entry(&wait, current);
1628                         add_wait_queue(&ctl->change_sleep, &wait);
1629                         set_current_state(TASK_INTERRUPTIBLE);
1630                         spin_unlock_irq(&ctl->read_lock);
1631                         schedule();
1632                         remove_wait_queue(&ctl->change_sleep, &wait);
1633                         if (ctl->card->shutdown)
1634                                 return -ENODEV;
1635                         if (signal_pending(current))
1636                                 return -ERESTARTSYS;
1637                         spin_lock_irq(&ctl->read_lock);
1638                 }
1639                 kev = snd_kctl_event(ctl->events.next);
1640                 ev.type = SNDRV_CTL_EVENT_ELEM;
1641                 ev.data.elem.mask = kev->mask;
1642                 ev.data.elem.id = kev->id;
1643                 list_del(&kev->list);
1644                 spin_unlock_irq(&ctl->read_lock);
1645                 kfree(kev);
1646                 if (copy_to_user(buffer, &ev, sizeof(struct snd_ctl_event))) {
1647                         err = -EFAULT;
1648                         goto __end;
1649                 }
1650                 spin_lock_irq(&ctl->read_lock);
1651                 buffer += sizeof(struct snd_ctl_event);
1652                 count -= sizeof(struct snd_ctl_event);
1653                 result += sizeof(struct snd_ctl_event);
1654         }
1655       __end_lock:
1656         spin_unlock_irq(&ctl->read_lock);
1657       __end:
1658         return result > 0 ? result : err;
1659 }
1660
1661 static __poll_t snd_ctl_poll(struct file *file, poll_table * wait)
1662 {
1663         __poll_t mask;
1664         struct snd_ctl_file *ctl;
1665
1666         ctl = file->private_data;
1667         if (!ctl->subscribed)
1668                 return 0;
1669         poll_wait(file, &ctl->change_sleep, wait);
1670
1671         mask = 0;
1672         if (!list_empty(&ctl->events))
1673                 mask |= EPOLLIN | EPOLLRDNORM;
1674
1675         return mask;
1676 }
1677
1678 /*
1679  * register the device-specific control-ioctls.
1680  * called from each device manager like pcm.c, hwdep.c, etc.
1681  */
1682 static int _snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn, struct list_head *lists)
1683 {
1684         struct snd_kctl_ioctl *pn;
1685
1686         pn = kzalloc(sizeof(struct snd_kctl_ioctl), GFP_KERNEL);
1687         if (pn == NULL)
1688                 return -ENOMEM;
1689         pn->fioctl = fcn;
1690         down_write(&snd_ioctl_rwsem);
1691         list_add_tail(&pn->list, lists);
1692         up_write(&snd_ioctl_rwsem);
1693         return 0;
1694 }
1695
1696 /**
1697  * snd_ctl_register_ioctl - register the device-specific control-ioctls
1698  * @fcn: ioctl callback function
1699  *
1700  * called from each device manager like pcm.c, hwdep.c, etc.
1701  */
1702 int snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn)
1703 {
1704         return _snd_ctl_register_ioctl(fcn, &snd_control_ioctls);
1705 }
1706 EXPORT_SYMBOL(snd_ctl_register_ioctl);
1707
1708 #ifdef CONFIG_COMPAT
1709 /**
1710  * snd_ctl_register_ioctl_compat - register the device-specific 32bit compat
1711  * control-ioctls
1712  * @fcn: ioctl callback function
1713  */
1714 int snd_ctl_register_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1715 {
1716         return _snd_ctl_register_ioctl(fcn, &snd_control_compat_ioctls);
1717 }
1718 EXPORT_SYMBOL(snd_ctl_register_ioctl_compat);
1719 #endif
1720
1721 /*
1722  * de-register the device-specific control-ioctls.
1723  */
1724 static int _snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn,
1725                                      struct list_head *lists)
1726 {
1727         struct snd_kctl_ioctl *p;
1728
1729         if (snd_BUG_ON(!fcn))
1730                 return -EINVAL;
1731         down_write(&snd_ioctl_rwsem);
1732         list_for_each_entry(p, lists, list) {
1733                 if (p->fioctl == fcn) {
1734                         list_del(&p->list);
1735                         up_write(&snd_ioctl_rwsem);
1736                         kfree(p);
1737                         return 0;
1738                 }
1739         }
1740         up_write(&snd_ioctl_rwsem);
1741         snd_BUG();
1742         return -EINVAL;
1743 }
1744
1745 /**
1746  * snd_ctl_unregister_ioctl - de-register the device-specific control-ioctls
1747  * @fcn: ioctl callback function to unregister
1748  */
1749 int snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn)
1750 {
1751         return _snd_ctl_unregister_ioctl(fcn, &snd_control_ioctls);
1752 }
1753 EXPORT_SYMBOL(snd_ctl_unregister_ioctl);
1754
1755 #ifdef CONFIG_COMPAT
1756 /**
1757  * snd_ctl_unregister_ioctl - de-register the device-specific compat 32bit
1758  * control-ioctls
1759  * @fcn: ioctl callback function to unregister
1760  */
1761 int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1762 {
1763         return _snd_ctl_unregister_ioctl(fcn, &snd_control_compat_ioctls);
1764 }
1765 EXPORT_SYMBOL(snd_ctl_unregister_ioctl_compat);
1766 #endif
1767
1768 static int snd_ctl_fasync(int fd, struct file * file, int on)
1769 {
1770         struct snd_ctl_file *ctl;
1771
1772         ctl = file->private_data;
1773         return fasync_helper(fd, file, on, &ctl->fasync);
1774 }
1775
1776 /* return the preferred subdevice number if already assigned;
1777  * otherwise return -1
1778  */
1779 int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type)
1780 {
1781         struct snd_ctl_file *kctl;
1782         int subdevice = -1;
1783
1784         read_lock(&card->ctl_files_rwlock);
1785         list_for_each_entry(kctl, &card->ctl_files, list) {
1786                 if (kctl->pid == task_pid(current)) {
1787                         subdevice = kctl->preferred_subdevice[type];
1788                         if (subdevice != -1)
1789                                 break;
1790                 }
1791         }
1792         read_unlock(&card->ctl_files_rwlock);
1793         return subdevice;
1794 }
1795 EXPORT_SYMBOL_GPL(snd_ctl_get_preferred_subdevice);
1796
1797 /*
1798  * ioctl32 compat
1799  */
1800 #ifdef CONFIG_COMPAT
1801 #include "control_compat.c"
1802 #else
1803 #define snd_ctl_ioctl_compat    NULL
1804 #endif
1805
1806 /*
1807  *  INIT PART
1808  */
1809
1810 static const struct file_operations snd_ctl_f_ops =
1811 {
1812         .owner =        THIS_MODULE,
1813         .read =         snd_ctl_read,
1814         .open =         snd_ctl_open,
1815         .release =      snd_ctl_release,
1816         .llseek =       no_llseek,
1817         .poll =         snd_ctl_poll,
1818         .unlocked_ioctl =       snd_ctl_ioctl,
1819         .compat_ioctl = snd_ctl_ioctl_compat,
1820         .fasync =       snd_ctl_fasync,
1821 };
1822
1823 /*
1824  * registration of the control device
1825  */
1826 static int snd_ctl_dev_register(struct snd_device *device)
1827 {
1828         struct snd_card *card = device->device_data;
1829
1830         return snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
1831                                    &snd_ctl_f_ops, card, &card->ctl_dev);
1832 }
1833
1834 /*
1835  * disconnection of the control device
1836  */
1837 static int snd_ctl_dev_disconnect(struct snd_device *device)
1838 {
1839         struct snd_card *card = device->device_data;
1840         struct snd_ctl_file *ctl;
1841
1842         read_lock(&card->ctl_files_rwlock);
1843         list_for_each_entry(ctl, &card->ctl_files, list) {
1844                 wake_up(&ctl->change_sleep);
1845                 kill_fasync(&ctl->fasync, SIGIO, POLL_ERR);
1846         }
1847         read_unlock(&card->ctl_files_rwlock);
1848
1849         return snd_unregister_device(&card->ctl_dev);
1850 }
1851
1852 /*
1853  * free all controls
1854  */
1855 static int snd_ctl_dev_free(struct snd_device *device)
1856 {
1857         struct snd_card *card = device->device_data;
1858         struct snd_kcontrol *control;
1859
1860         down_write(&card->controls_rwsem);
1861         while (!list_empty(&card->controls)) {
1862                 control = snd_kcontrol(card->controls.next);
1863                 snd_ctl_remove(card, control);
1864         }
1865         up_write(&card->controls_rwsem);
1866         put_device(&card->ctl_dev);
1867         return 0;
1868 }
1869
1870 /*
1871  * create control core:
1872  * called from init.c
1873  */
1874 int snd_ctl_create(struct snd_card *card)
1875 {
1876         static struct snd_device_ops ops = {
1877                 .dev_free = snd_ctl_dev_free,
1878                 .dev_register = snd_ctl_dev_register,
1879                 .dev_disconnect = snd_ctl_dev_disconnect,
1880         };
1881         int err;
1882
1883         if (snd_BUG_ON(!card))
1884                 return -ENXIO;
1885         if (snd_BUG_ON(card->number < 0 || card->number >= SNDRV_CARDS))
1886                 return -ENXIO;
1887
1888         snd_device_initialize(&card->ctl_dev, card);
1889         dev_set_name(&card->ctl_dev, "controlC%d", card->number);
1890
1891         err = snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
1892         if (err < 0)
1893                 put_device(&card->ctl_dev);
1894         return err;
1895 }
1896
1897 /*
1898  * Frequently used control callbacks/helpers
1899  */
1900
1901 /**
1902  * snd_ctl_boolean_mono_info - Helper function for a standard boolean info
1903  * callback with a mono channel
1904  * @kcontrol: the kcontrol instance
1905  * @uinfo: info to store
1906  *
1907  * This is a function that can be used as info callback for a standard
1908  * boolean control with a single mono channel.
1909  */
1910 int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
1911                               struct snd_ctl_elem_info *uinfo)
1912 {
1913         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1914         uinfo->count = 1;
1915         uinfo->value.integer.min = 0;
1916         uinfo->value.integer.max = 1;
1917         return 0;
1918 }
1919 EXPORT_SYMBOL(snd_ctl_boolean_mono_info);
1920
1921 /**
1922  * snd_ctl_boolean_stereo_info - Helper function for a standard boolean info
1923  * callback with stereo two channels
1924  * @kcontrol: the kcontrol instance
1925  * @uinfo: info to store
1926  *
1927  * This is a function that can be used as info callback for a standard
1928  * boolean control with stereo two channels.
1929  */
1930 int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
1931                                 struct snd_ctl_elem_info *uinfo)
1932 {
1933         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1934         uinfo->count = 2;
1935         uinfo->value.integer.min = 0;
1936         uinfo->value.integer.max = 1;
1937         return 0;
1938 }
1939 EXPORT_SYMBOL(snd_ctl_boolean_stereo_info);
1940
1941 /**
1942  * snd_ctl_enum_info - fills the info structure for an enumerated control
1943  * @info: the structure to be filled
1944  * @channels: the number of the control's channels; often one
1945  * @items: the number of control values; also the size of @names
1946  * @names: an array containing the names of all control values
1947  *
1948  * Sets all required fields in @info to their appropriate values.
1949  * If the control's accessibility is not the default (readable and writable),
1950  * the caller has to fill @info->access.
1951  *
1952  * Return: Zero.
1953  */
1954 int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
1955                       unsigned int items, const char *const names[])
1956 {
1957         info->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
1958         info->count = channels;
1959         info->value.enumerated.items = items;
1960         if (!items)
1961                 return 0;
1962         if (info->value.enumerated.item >= items)
1963                 info->value.enumerated.item = items - 1;
1964         WARN(strlen(names[info->value.enumerated.item]) >= sizeof(info->value.enumerated.name),
1965              "ALSA: too long item name '%s'\n",
1966              names[info->value.enumerated.item]);
1967         strlcpy(info->value.enumerated.name,
1968                 names[info->value.enumerated.item],
1969                 sizeof(info->value.enumerated.name));
1970         return 0;
1971 }
1972 EXPORT_SYMBOL(snd_ctl_enum_info);