sound/core/control.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Routines for driver control interface
   4  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
   5  */
   6
   7 #include <linux/threads.h>
   8 #include <linux/interrupt.h>
   9 #include <linux/module.h>
  10 #include <linux/slab.h>
  11 #include <linux/vmalloc.h>
  12 #include <linux/time.h>
  13 #include <linux/mm.h>
  14 #include <linux/sched/signal.h>
  15 #include <sound/core.h>
  16 #include <sound/minors.h>
  17 #include <sound/info.h>
  18 #include <sound/control.h>
  19
  20 /* max number of user-defined controls */
  21 #define MAX_USER_CONTROLS       32
  22 #define MAX_CONTROL_COUNT       1028
  23
  24 struct snd_kctl_ioctl {
  25         struct list_head list;          /* list of all ioctls */
  26         snd_kctl_ioctl_func_t fioctl;
  27 };
  28
  29 static DECLARE_RWSEM(snd_ioctl_rwsem);
  30 static LIST_HEAD(snd_control_ioctls);
  31 #ifdef CONFIG_COMPAT
  32 static LIST_HEAD(snd_control_compat_ioctls);
  33 #endif
  34
  35 static int snd_ctl_open(struct inode *inode, struct file *file)
  36 {
  37         unsigned long flags;
  38         struct snd_card *card;
  39         struct snd_ctl_file *ctl;
  40         int i, err;
  41
  42         err = stream_open(inode, file);
  43         if (err < 0)
  44                 return err;
  45
  46         card = snd_lookup_minor_data(iminor(inode), SNDRV_DEVICE_TYPE_CONTROL);
  47         if (!card) {
  48                 err = -ENODEV;
  49                 goto __error1;
  50         }
  51         err = snd_card_file_add(card, file);
  52         if (err < 0) {
  53                 err = -ENODEV;
  54                 goto __error1;
  55         }
  56         if (!try_module_get(card->module)) {
  57                 err = -EFAULT;
  58                 goto __error2;
  59         }
  60         ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);
  61         if (ctl == NULL) {
  62                 err = -ENOMEM;
  63                 goto __error;
  64         }
  65         INIT_LIST_HEAD(&ctl->events);
  66         init_waitqueue_head(&ctl->change_sleep);
  67         spin_lock_init(&ctl->read_lock);
  68         ctl->card = card;
  69         for (i = 0; i < SND_CTL_SUBDEV_ITEMS; i++)
  70                 ctl->preferred_subdevice[i] = -1;
  71         ctl->pid = get_pid(task_pid(current));
  72         file->private_data = ctl;
  73         write_lock_irqsave(&card->ctl_files_rwlock, flags);
  74         list_add_tail(&ctl->list, &card->ctl_files);
  75         write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
  76         snd_card_unref(card);
  77         return 0;
  78
  79       __error:
  80         module_put(card->module);
  81       __error2:
  82         snd_card_file_remove(card, file);
  83       __error1:
  84         if (card)
  85                 snd_card_unref(card);
  86         return err;
  87 }
  88
  89 static void snd_ctl_empty_read_queue(struct snd_ctl_file * ctl)
  90 {
  91         unsigned long flags;
  92         struct snd_kctl_event *cread;
  93
  94         spin_lock_irqsave(&ctl->read_lock, flags);
  95         while (!list_empty(&ctl->events)) {
  96                 cread = snd_kctl_event(ctl->events.next);
  97                 list_del(&cread->list);
  98                 kfree(cread);
  99         }
 100         spin_unlock_irqrestore(&ctl->read_lock, flags);
 101 }
 102
 103 static int snd_ctl_release(struct inode *inode, struct file *file)
 104 {
 105         unsigned long flags;
 106         struct snd_card *card;
 107         struct snd_ctl_file *ctl;
 108         struct snd_kcontrol *control;
 109         unsigned int idx;
 110
 111         ctl = file->private_data;
 112         file->private_data = NULL;
 113         card = ctl->card;
 114         write_lock_irqsave(&card->ctl_files_rwlock, flags);
 115         list_del(&ctl->list);
 116         write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
 117         down_write(&card->controls_rwsem);
 118         list_for_each_entry(control, &card->controls, list)
 119                 for (idx = 0; idx < control->count; idx++)
 120                         if (control->vd[idx].owner == ctl)
 121                                 control->vd[idx].owner = NULL;
 122         up_write(&card->controls_rwsem);
 123         snd_ctl_empty_read_queue(ctl);
 124         put_pid(ctl->pid);
 125         kfree(ctl);
 126         module_put(card->module);
 127         snd_card_file_remove(card, file);
 128         return 0;
 129 }
 130
 131 /**
 132  * snd_ctl_notify - Send notification to user-space for a control change
 133  * @card: the card to send notification
 134  * @mask: the event mask, SNDRV_CTL_EVENT_*
 135  * @id: the ctl element id to send notification
 136  *
 137  * This function adds an event record with the given id and mask, appends
 138  * to the list and wakes up the user-space for notification.  This can be
 139  * called in the atomic context.
 140  */
 141 void snd_ctl_notify(struct snd_card *card, unsigned int mask,
 142                     struct snd_ctl_elem_id *id)
 143 {
 144         unsigned long flags;
 145         struct snd_ctl_file *ctl;
 146         struct snd_kctl_event *ev;
 147
 148         if (snd_BUG_ON(!card || !id))
 149                 return;
 150         if (card->shutdown)
 151                 return;
 152         read_lock(&card->ctl_files_rwlock);
 153 #if IS_ENABLED(CONFIG_SND_MIXER_OSS)
 154         card->mixer_oss_change_count++;
 155 #endif
 156         list_for_each_entry(ctl, &card->ctl_files, list) {
 157                 if (!ctl->subscribed)
 158                         continue;
 159                 spin_lock_irqsave(&ctl->read_lock, flags);
 160                 list_for_each_entry(ev, &ctl->events, list) {
 161                         if (ev->id.numid == id->numid) {
 162                                 ev->mask |= mask;
 163                                 goto _found;
 164                         }
 165                 }
 166                 ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
 167                 if (ev) {
 168                         ev->id = *id;
 169                         ev->mask = mask;
 170                         list_add_tail(&ev->list, &ctl->events);
 171                 } else {
 172                         dev_err(card->dev, "No memory available to allocate event\n");
 173                 }
 174         _found:
 175                 wake_up(&ctl->change_sleep);
 176                 spin_unlock_irqrestore(&ctl->read_lock, flags);
 177                 kill_fasync(&ctl->fasync, SIGIO, POLL_IN);
 178         }
 179         read_unlock(&card->ctl_files_rwlock);
 180 }
 181 EXPORT_SYMBOL(snd_ctl_notify);
 182
 183 /**
 184  * snd_ctl_new - create a new control instance with some elements
 185  * @kctl: the pointer to store new control instance
 186  * @count: the number of elements in this control
 187  * @access: the default access flags for elements in this control
 188  * @file: given when locking these elements
 189  *
 190  * Allocates a memory object for a new control instance. The instance has
 191  * elements as many as the given number (@count). Each element has given
 192  * access permissions (@access). Each element is locked when @file is given.
 193  *
 194  * Return: 0 on success, error code on failure
 195  */
 196 static int snd_ctl_new(struct snd_kcontrol **kctl, unsigned int count,
 197                        unsigned int access, struct snd_ctl_file *file)
 198 {
 199         unsigned int idx;
 200
 201         if (count == 0 || count > MAX_CONTROL_COUNT)
 202                 return -EINVAL;
 203
 204         *kctl = kzalloc(struct_size(*kctl, vd, count), GFP_KERNEL);
 205         if (!*kctl)
 206                 return -ENOMEM;
 207
 208         for (idx = 0; idx < count; idx++) {
 209                 (*kctl)->vd[idx].access = access;
 210                 (*kctl)->vd[idx].owner = file;
 211         }
 212         (*kctl)->count = count;
 213
 214         return 0;
 215 }
 216
 217 /**
 218  * snd_ctl_new1 - create a control instance from the template
 219  * @ncontrol: the initialization record
 220  * @private_data: the private data to set
 221  *
 222  * Allocates a new struct snd_kcontrol instance and initialize from the given
 223  * template.  When the access field of ncontrol is 0, it's assumed as
 224  * READWRITE access. When the count field is 0, it's assumes as one.
 225  *
 226  * Return: The pointer of the newly generated instance, or %NULL on failure.
 227  */
 228 struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new *ncontrol,
 229                                   void *private_data)
 230 {
 231         struct snd_kcontrol *kctl;
 232         unsigned int count;
 233         unsigned int access;
 234         int err;
 235
 236         if (snd_BUG_ON(!ncontrol || !ncontrol->info))
 237                 return NULL;
 238
 239         count = ncontrol->count;
 240         if (count == 0)
 241                 count = 1;
 242
 243         access = ncontrol->access;
 244         if (access == 0)
 245                 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
 246         access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
 247                    SNDRV_CTL_ELEM_ACCESS_VOLATILE |
 248                    SNDRV_CTL_ELEM_ACCESS_INACTIVE |
 249                    SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE |
 250                    SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND |
 251                    SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
 252
 253         err = snd_ctl_new(&kctl, count, access, NULL);
 254         if (err < 0)
 255                 return NULL;
 256
 257         /* The 'numid' member is decided when calling snd_ctl_add(). */
 258         kctl->id.iface = ncontrol->iface;
 259         kctl->id.device = ncontrol->device;
 260         kctl->id.subdevice = ncontrol->subdevice;
 261         if (ncontrol->name) {
 262                 strlcpy(kctl->id.name, ncontrol->name, sizeof(kctl->id.name));
 263                 if (strcmp(ncontrol->name, kctl->id.name) != 0)
 264                         pr_warn("ALSA: Control name '%s' truncated to '%s'\n",
 265                                 ncontrol->name, kctl->id.name);
 266         }
 267         kctl->id.index = ncontrol->index;
 268
 269         kctl->info = ncontrol->info;
 270         kctl->get = ncontrol->get;
 271         kctl->put = ncontrol->put;
 272         kctl->tlv.p = ncontrol->tlv.p;
 273
 274         kctl->private_value = ncontrol->private_value;
 275         kctl->private_data = private_data;
 276
 277         return kctl;
 278 }
 279 EXPORT_SYMBOL(snd_ctl_new1);
 280
 281 /**
 282  * snd_ctl_free_one - release the control instance
 283  * @kcontrol: the control instance
 284  *
 285  * Releases the control instance created via snd_ctl_new()
 286  * or snd_ctl_new1().
 287  * Don't call this after the control was added to the card.
 288  */
 289 void snd_ctl_free_one(struct snd_kcontrol *kcontrol)
 290 {
 291         if (kcontrol) {
 292                 if (kcontrol->private_free)
 293                         kcontrol->private_free(kcontrol);
 294                 kfree(kcontrol);
 295         }
 296 }
 297 EXPORT_SYMBOL(snd_ctl_free_one);
 298
 299 static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
 300                                           unsigned int count)
 301 {
 302         struct snd_kcontrol *kctl;
 303
 304         /* Make sure that the ids assigned to the control do not wrap around */
 305         if (card->last_numid >= UINT_MAX - count)
 306                 card->last_numid = 0;
 307
 308         list_for_each_entry(kctl, &card->controls, list) {
 309                 if (kctl->id.numid < card->last_numid + 1 + count &&
 310                     kctl->id.numid + kctl->count > card->last_numid + 1) {
 311                         card->last_numid = kctl->id.numid + kctl->count - 1;
 312                         return true;
 313                 }
 314         }
 315         return false;
 316 }
 317
 318 static int snd_ctl_find_hole(struct snd_card *card, unsigned int count)
 319 {
 320         unsigned int iter = 100000;
 321
 322         while (snd_ctl_remove_numid_conflict(card, count)) {
 323                 if (--iter == 0) {
 324                         /* this situation is very unlikely */
 325                         dev_err(card->dev, "unable to allocate new control numid\n");
 326                         return -ENOMEM;
 327                 }
 328         }
 329         return 0;
 330 }
 331
 332 enum snd_ctl_add_mode {
 333         CTL_ADD_EXCLUSIVE, CTL_REPLACE, CTL_ADD_ON_REPLACE,
 334 };
 335
 336 /* add/replace a new kcontrol object; call with card->controls_rwsem locked */
 337 static int __snd_ctl_add_replace(struct snd_card *card,
 338                                  struct snd_kcontrol *kcontrol,
 339                                  enum snd_ctl_add_mode mode)
 340 {
 341         struct snd_ctl_elem_id id;
 342         unsigned int idx;
 343         unsigned int count;
 344         struct snd_kcontrol *old;
 345         int err;
 346
 347         id = kcontrol->id;
 348         if (id.index > UINT_MAX - kcontrol->count)
 349                 return -EINVAL;
 350
 351         old = snd_ctl_find_id(card, &id);
 352         if (!old) {
 353                 if (mode == CTL_REPLACE)
 354                         return -EINVAL;
 355         } else {
 356                 if (mode == CTL_ADD_EXCLUSIVE) {
 357                         dev_err(card->dev,
 358                                 "control %i:%i:%i:%s:%i is already present\n",
 359                                 id.iface, id.device, id.subdevice, id.name,
 360                                 id.index);
 361                         return -EBUSY;
 362                 }
 363
 364                 err = snd_ctl_remove(card, old);
 365                 if (err < 0)
 366                         return err;
 367         }
 368
 369         if (snd_ctl_find_hole(card, kcontrol->count) < 0)
 370                 return -ENOMEM;
 371
 372         list_add_tail(&kcontrol->list, &card->controls);
 373         card->controls_count += kcontrol->count;
 374         kcontrol->id.numid = card->last_numid + 1;
 375         card->last_numid += kcontrol->count;
 376
 377         id = kcontrol->id;
 378         count = kcontrol->count;
 379         for (idx = 0; idx < count; idx++, id.index++, id.numid++)
 380                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
 381
 382         return 0;
 383 }
 384
 385 static int snd_ctl_add_replace(struct snd_card *card,
 386                                struct snd_kcontrol *kcontrol,
 387                                enum snd_ctl_add_mode mode)
 388 {
 389         int err = -EINVAL;
 390
 391         if (! kcontrol)
 392                 return err;
 393         if (snd_BUG_ON(!card || !kcontrol->info))
 394                 goto error;
 395
 396         down_write(&card->controls_rwsem);
 397         err = __snd_ctl_add_replace(card, kcontrol, mode);
 398         up_write(&card->controls_rwsem);
 399         if (err < 0)
 400                 goto error;
 401         return 0;
 402
 403  error:
 404         snd_ctl_free_one(kcontrol);
 405         return err;
 406 }
 407
 408 /**
 409  * snd_ctl_add - add the control instance to the card
 410  * @card: the card instance
 411  * @kcontrol: the control instance to add
 412  *
 413  * Adds the control instance created via snd_ctl_new() or
 414  * snd_ctl_new1() to the given card. Assigns also an unique
 415  * numid used for fast search.
 416  *
 417  * It frees automatically the control which cannot be added.
 418  *
 419  * Return: Zero if successful, or a negative error code on failure.
 420  *
 421  */
 422 int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
 423 {
 424         return snd_ctl_add_replace(card, kcontrol, CTL_ADD_EXCLUSIVE);
 425 }
 426 EXPORT_SYMBOL(snd_ctl_add);
 427
 428 /**
 429  * snd_ctl_replace - replace the control instance of the card
 430  * @card: the card instance
 431  * @kcontrol: the control instance to replace
 432  * @add_on_replace: add the control if not already added
 433  *
 434  * Replaces the given control.  If the given control does not exist
 435  * and the add_on_replace flag is set, the control is added.  If the
 436  * control exists, it is destroyed first.
 437  *
 438  * It frees automatically the control which cannot be added or replaced.
 439  *
 440  * Return: Zero if successful, or a negative error code on failure.
 441  */
 442 int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
 443                     bool add_on_replace)
 444 {
 445         return snd_ctl_add_replace(card, kcontrol,
 446                                    add_on_replace ? CTL_ADD_ON_REPLACE : CTL_REPLACE);
 447 }
 448 EXPORT_SYMBOL(snd_ctl_replace);
 449
 450 /**
 451  * snd_ctl_remove - remove the control from the card and release it
 452  * @card: the card instance
 453  * @kcontrol: the control instance to remove
 454  *
 455  * Removes the control from the card and then releases the instance.
 456  * You don't need to call snd_ctl_free_one(). You must be in
 457  * the write lock - down_write(&card->controls_rwsem).
 458  *
 459  * Return: 0 if successful, or a negative error code on failure.
 460  */
 461 int snd_ctl_remove(struct snd_card *card, struct snd_kcontrol *kcontrol)
 462 {
 463         struct snd_ctl_elem_id id;
 464         unsigned int idx;
 465
 466         if (snd_BUG_ON(!card || !kcontrol))
 467                 return -EINVAL;
 468         list_del(&kcontrol->list);
 469         card->controls_count -= kcontrol->count;
 470         id = kcontrol->id;
 471         for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
 472                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_REMOVE, &id);
 473         snd_ctl_free_one(kcontrol);
 474         return 0;
 475 }
 476 EXPORT_SYMBOL(snd_ctl_remove);
 477
 478 /**
 479  * snd_ctl_remove_id - remove the control of the given id and release it
 480  * @card: the card instance
 481  * @id: the control id to remove
 482  *
 483  * Finds the control instance with the given id, removes it from the
 484  * card list and releases it.
 485  *
 486  * Return: 0 if successful, or a negative error code on failure.
 487  */
 488 int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
 489 {
 490         struct snd_kcontrol *kctl;
 491         int ret;
 492
 493         down_write(&card->controls_rwsem);
 494         kctl = snd_ctl_find_id(card, id);
 495         if (kctl == NULL) {
 496                 up_write(&card->controls_rwsem);
 497                 return -ENOENT;
 498         }
 499         ret = snd_ctl_remove(card, kctl);
 500         up_write(&card->controls_rwsem);
 501         return ret;
 502 }
 503 EXPORT_SYMBOL(snd_ctl_remove_id);
 504
 505 /**
 506  * snd_ctl_remove_user_ctl - remove and release the unlocked user control
 507  * @file: active control handle
 508  * @id: the control id to remove
 509  *
 510  * Finds the control instance with the given id, removes it from the
 511  * card list and releases it.
 512  *
 513  * Return: 0 if successful, or a negative error code on failure.
 514  */
 515 static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
 516                                    struct snd_ctl_elem_id *id)
 517 {
 518         struct snd_card *card = file->card;
 519         struct snd_kcontrol *kctl;
 520         int idx, ret;
 521
 522         down_write(&card->controls_rwsem);
 523         kctl = snd_ctl_find_id(card, id);
 524         if (kctl == NULL) {
 525                 ret = -ENOENT;
 526                 goto error;
 527         }
 528         if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER)) {
 529                 ret = -EINVAL;
 530                 goto error;
 531         }
 532         for (idx = 0; idx < kctl->count; idx++)
 533                 if (kctl->vd[idx].owner != NULL && kctl->vd[idx].owner != file) {
 534                         ret = -EBUSY;
 535                         goto error;
 536                 }
 537         ret = snd_ctl_remove(card, kctl);
 538         if (ret < 0)
 539                 goto error;
 540         card->user_ctl_count--;
 541 error:
 542         up_write(&card->controls_rwsem);
 543         return ret;
 544 }
 545
 546 /**
 547  * snd_ctl_activate_id - activate/inactivate the control of the given id
 548  * @card: the card instance
 549  * @id: the control id to activate/inactivate
 550  * @active: non-zero to activate
 551  *
 552  * Finds the control instance with the given id, and activate or
 553  * inactivate the control together with notification, if changed.
 554  * The given ID data is filled with full information.
 555  *
 556  * Return: 0 if unchanged, 1 if changed, or a negative error code on failure.
 557  */
 558 int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
 559                         int active)
 560 {
 561         struct snd_kcontrol *kctl;
 562         struct snd_kcontrol_volatile *vd;
 563         unsigned int index_offset;
 564         int ret;
 565
 566         down_write(&card->controls_rwsem);
 567         kctl = snd_ctl_find_id(card, id);
 568         if (kctl == NULL) {
 569                 ret = -ENOENT;
 570                 goto unlock;
 571         }
 572         index_offset = snd_ctl_get_ioff(kctl, id);
 573         vd = &kctl->vd[index_offset];
 574         ret = 0;
 575         if (active) {
 576                 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
 577                         goto unlock;
 578                 vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
 579         } else {
 580                 if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
 581                         goto unlock;
 582                 vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
 583         }
 584         snd_ctl_build_ioff(id, kctl, index_offset);
 585         ret = 1;
 586  unlock:
 587         up_write(&card->controls_rwsem);
 588         if (ret > 0)
 589                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, id);
 590         return ret;
 591 }
 592 EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
 593
 594 /**
 595  * snd_ctl_rename_id - replace the id of a control on the card
 596  * @card: the card instance
 597  * @src_id: the old id
 598  * @dst_id: the new id
 599  *
 600  * Finds the control with the old id from the card, and replaces the
 601  * id with the new one.
 602  *
 603  * Return: Zero if successful, or a negative error code on failure.
 604  */
 605 int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
 606                       struct snd_ctl_elem_id *dst_id)
 607 {
 608         struct snd_kcontrol *kctl;
 609
 610         down_write(&card->controls_rwsem);
 611         kctl = snd_ctl_find_id(card, src_id);
 612         if (kctl == NULL) {
 613                 up_write(&card->controls_rwsem);
 614                 return -ENOENT;
 615         }
 616         kctl->id = *dst_id;
 617         kctl->id.numid = card->last_numid + 1;
 618         card->last_numid += kctl->count;
 619         up_write(&card->controls_rwsem);
 620         return 0;
 621 }
 622 EXPORT_SYMBOL(snd_ctl_rename_id);
 623
 624 /**
 625  * snd_ctl_find_numid - find the control instance with the given number-id
 626  * @card: the card instance
 627  * @numid: the number-id to search
 628  *
 629  * Finds the control instance with the given number-id from the card.
 630  *
 631  * The caller must down card->controls_rwsem before calling this function
 632  * (if the race condition can happen).
 633  *
 634  * Return: The pointer of the instance if found, or %NULL if not.
 635  *
 636  */
 637 struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card, unsigned int numid)
 638 {
 639         struct snd_kcontrol *kctl;
 640
 641         if (snd_BUG_ON(!card || !numid))
 642                 return NULL;
 643         list_for_each_entry(kctl, &card->controls, list) {
 644                 if (kctl->id.numid <= numid && kctl->id.numid + kctl->count > numid)
 645                         return kctl;
 646         }
 647         return NULL;
 648 }
 649 EXPORT_SYMBOL(snd_ctl_find_numid);
 650
 651 /**
 652  * snd_ctl_find_id - find the control instance with the given id
 653  * @card: the card instance
 654  * @id: the id to search
 655  *
 656  * Finds the control instance with the given id from the card.
 657  *
 658  * The caller must down card->controls_rwsem before calling this function
 659  * (if the race condition can happen).
 660  *
 661  * Return: The pointer of the instance if found, or %NULL if not.
 662  *
 663  */
 664 struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
 665                                      struct snd_ctl_elem_id *id)
 666 {
 667         struct snd_kcontrol *kctl;
 668
 669         if (snd_BUG_ON(!card || !id))
 670                 return NULL;
 671         if (id->numid != 0)
 672                 return snd_ctl_find_numid(card, id->numid);
 673         list_for_each_entry(kctl, &card->controls, list) {
 674                 if (kctl->id.iface != id->iface)
 675                         continue;
 676                 if (kctl->id.device != id->device)
 677                         continue;
 678                 if (kctl->id.subdevice != id->subdevice)
 679                         continue;
 680                 if (strncmp(kctl->id.name, id->name, sizeof(kctl->id.name)))
 681                         continue;
 682                 if (kctl->id.index > id->index)
 683                         continue;
 684                 if (kctl->id.index + kctl->count <= id->index)
 685                         continue;
 686                 return kctl;
 687         }
 688         return NULL;
 689 }
 690 EXPORT_SYMBOL(snd_ctl_find_id);
 691
 692 static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,
 693                              unsigned int cmd, void __user *arg)
 694 {
 695         struct snd_ctl_card_info *info;
 696
 697         info = kzalloc(sizeof(*info), GFP_KERNEL);
 698         if (! info)
 699                 return -ENOMEM;
 700         down_read(&snd_ioctl_rwsem);
 701         info->card = card->number;
 702         strlcpy(info->id, card->id, sizeof(info->id));
 703         strlcpy(info->driver, card->driver, sizeof(info->driver));
 704         strlcpy(info->name, card->shortname, sizeof(info->name));
 705         strlcpy(info->longname, card->longname, sizeof(info->longname));
 706         strlcpy(info->mixername, card->mixername, sizeof(info->mixername));
 707         strlcpy(info->components, card->components, sizeof(info->components));
 708         up_read(&snd_ioctl_rwsem);
 709         if (copy_to_user(arg, info, sizeof(struct snd_ctl_card_info))) {
 710                 kfree(info);
 711                 return -EFAULT;
 712         }
 713         kfree(info);
 714         return 0;
 715 }
 716
 717 static int snd_ctl_elem_list(struct snd_card *card,
 718                              struct snd_ctl_elem_list __user *_list)
 719 {
 720         struct snd_ctl_elem_list list;
 721         struct snd_kcontrol *kctl;
 722         struct snd_ctl_elem_id id;
 723         unsigned int offset, space, jidx;
 724         int err = 0;
 725
 726         if (copy_from_user(&list, _list, sizeof(list)))
 727                 return -EFAULT;
 728         offset = list.offset;
 729         space = list.space;
 730
 731         down_read(&card->controls_rwsem);
 732         list.count = card->controls_count;
 733         list.used = 0;
 734         if (space > 0) {
 735                 list_for_each_entry(kctl, &card->controls, list) {
 736                         if (offset >= kctl->count) {
 737                                 offset -= kctl->count;
 738                                 continue;
 739                         }
 740                         for (jidx = offset; jidx < kctl->count; jidx++) {
 741                                 snd_ctl_build_ioff(&id, kctl, jidx);
 742                                 if (copy_to_user(list.pids + list.used, &id,
 743                                                  sizeof(id))) {
 744                                         err = -EFAULT;
 745                                         goto out;
 746                                 }
 747                                 list.used++;
 748                                 if (!--space)
 749                                         goto out;
 750                         }
 751                         offset = 0;
 752                 }
 753         }
 754  out:
 755         up_read(&card->controls_rwsem);
 756         if (!err && copy_to_user(_list, &list, sizeof(list)))
 757                 err = -EFAULT;
 758         return err;
 759 }
 760
 761 static bool validate_element_member_dimension(struct snd_ctl_elem_info *info)
 762 {
 763         unsigned int members;
 764         unsigned int i;
 765
 766         if (info->dimen.d[0] == 0)
 767                 return true;
 768
 769         members = 1;
 770         for (i = 0; i < ARRAY_SIZE(info->dimen.d); ++i) {
 771                 if (info->dimen.d[i] == 0)
 772                         break;
 773                 members *= info->dimen.d[i];
 774
 775                 /*
 776                  * info->count should be validated in advance, to guarantee
 777                  * calculation soundness.
 778                  */
 779                 if (members > info->count)
 780                         return false;
 781         }
 782
 783         for (++i; i < ARRAY_SIZE(info->dimen.d); ++i) {
 784                 if (info->dimen.d[i] > 0)
 785                         return false;
 786         }
 787
 788         return members == info->count;
 789 }
 790
 791 static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
 792                              struct snd_ctl_elem_info *info)
 793 {
 794         struct snd_card *card = ctl->card;
 795         struct snd_kcontrol *kctl;
 796         struct snd_kcontrol_volatile *vd;
 797         unsigned int index_offset;
 798         int result;
 799
 800         down_read(&card->controls_rwsem);
 801         kctl = snd_ctl_find_id(card, &info->id);
 802         if (kctl == NULL) {
 803                 up_read(&card->controls_rwsem);
 804                 return -ENOENT;
 805         }
 806 #ifdef CONFIG_SND_DEBUG
 807         info->access = 0;
 808 #endif
 809         result = kctl->info(kctl, info);
 810         if (result >= 0) {
 811                 snd_BUG_ON(info->access);
 812                 index_offset = snd_ctl_get_ioff(kctl, &info->id);
 813                 vd = &kctl->vd[index_offset];
 814                 snd_ctl_build_ioff(&info->id, kctl, index_offset);
 815                 info->access = vd->access;
 816                 if (vd->owner) {
 817                         info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
 818                         if (vd->owner == ctl)
 819                                 info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
 820                         info->owner = pid_vnr(vd->owner->pid);
 821                 } else {
 822                         info->owner = -1;
 823                 }
 824         }
 825         up_read(&card->controls_rwsem);
 826         return result;
 827 }
 828
 829 static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
 830                                   struct snd_ctl_elem_info __user *_info)
 831 {
 832         struct snd_ctl_elem_info info;
 833         int result;
 834
 835         if (copy_from_user(&info, _info, sizeof(info)))
 836                 return -EFAULT;
 837         result = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);
 838         if (result < 0)
 839                 return result;
 840         result = snd_ctl_elem_info(ctl, &info);
 841         if (result < 0)
 842                 return result;
 843         if (copy_to_user(_info, &info, sizeof(info)))
 844                 return -EFAULT;
 845         return result;
 846 }
 847
 848 static int snd_ctl_elem_read(struct snd_card *card,
 849                              struct snd_ctl_elem_value *control)
 850 {
 851         struct snd_kcontrol *kctl;
 852         struct snd_kcontrol_volatile *vd;
 853         unsigned int index_offset;
 854
 855         kctl = snd_ctl_find_id(card, &control->id);
 856         if (kctl == NULL)
 857                 return -ENOENT;
 858
 859         index_offset = snd_ctl_get_ioff(kctl, &control->id);
 860         vd = &kctl->vd[index_offset];
 861         if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_READ) || kctl->get == NULL)
 862                 return -EPERM;
 863
 864         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 865         return kctl->get(kctl, control);
 866 }
 867
 868 static int snd_ctl_elem_read_user(struct snd_card *card,
 869                                   struct snd_ctl_elem_value __user *_control)
 870 {
 871         struct snd_ctl_elem_value *control;
 872         int result;
 873
 874         control = memdup_user(_control, sizeof(*control));
 875         if (IS_ERR(control))
 876                 return PTR_ERR(control);
 877
 878         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 879         if (result < 0)
 880                 goto error;
 881
 882         down_read(&card->controls_rwsem);
 883         result = snd_ctl_elem_read(card, control);
 884         up_read(&card->controls_rwsem);
 885         if (result < 0)
 886                 goto error;
 887
 888         if (copy_to_user(_control, control, sizeof(*control)))
 889                 result = -EFAULT;
 890  error:
 891         kfree(control);
 892         return result;
 893 }
 894
 895 static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
 896                               struct snd_ctl_elem_value *control)
 897 {
 898         struct snd_kcontrol *kctl;
 899         struct snd_kcontrol_volatile *vd;
 900         unsigned int index_offset;
 901         int result;
 902
 903         kctl = snd_ctl_find_id(card, &control->id);
 904         if (kctl == NULL)
 905                 return -ENOENT;
 906
 907         index_offset = snd_ctl_get_ioff(kctl, &control->id);
 908         vd = &kctl->vd[index_offset];
 909         if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_WRITE) || kctl->put == NULL ||
 910             (file && vd->owner && vd->owner != file)) {
 911                 return -EPERM;
 912         }
 913
 914         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 915         result = kctl->put(kctl, control);
 916         if (result < 0)
 917                 return result;
 918
 919         if (result > 0) {
 920                 struct snd_ctl_elem_id id = control->id;
 921                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, &id);
 922         }
 923
 924         return 0;
 925 }
 926
 927 static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
 928                                    struct snd_ctl_elem_value __user *_control)
 929 {
 930         struct snd_ctl_elem_value *control;
 931         struct snd_card *card;
 932         int result;
 933
 934         control = memdup_user(_control, sizeof(*control));
 935         if (IS_ERR(control))
 936                 return PTR_ERR(control);
 937
 938         card = file->card;
 939         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 940         if (result < 0)
 941                 goto error;
 942
 943         down_write(&card->controls_rwsem);
 944         result = snd_ctl_elem_write(card, file, control);
 945         up_write(&card->controls_rwsem);
 946         if (result < 0)
 947                 goto error;
 948
 949         if (copy_to_user(_control, control, sizeof(*control)))
 950                 result = -EFAULT;
 951  error:
 952         kfree(control);
 953         return result;
 954 }
 955
 956 static int snd_ctl_elem_lock(struct snd_ctl_file *file,
 957                              struct snd_ctl_elem_id __user *_id)
 958 {
 959         struct snd_card *card = file->card;
 960         struct snd_ctl_elem_id id;
 961         struct snd_kcontrol *kctl;
 962         struct snd_kcontrol_volatile *vd;
 963         int result;
 964
 965         if (copy_from_user(&id, _id, sizeof(id)))
 966                 return -EFAULT;
 967         down_write(&card->controls_rwsem);
 968         kctl = snd_ctl_find_id(card, &id);
 969         if (kctl == NULL) {
 970                 result = -ENOENT;
 971         } else {
 972                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
 973                 if (vd->owner != NULL)
 974                         result = -EBUSY;
 975                 else {
 976                         vd->owner = file;
 977                         result = 0;
 978                 }
 979         }
 980         up_write(&card->controls_rwsem);
 981         return result;
 982 }
 983
 984 static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
 985                                struct snd_ctl_elem_id __user *_id)
 986 {
 987         struct snd_card *card = file->card;
 988         struct snd_ctl_elem_id id;
 989         struct snd_kcontrol *kctl;
 990         struct snd_kcontrol_volatile *vd;
 991         int result;
 992
 993         if (copy_from_user(&id, _id, sizeof(id)))
 994                 return -EFAULT;
 995         down_write(&card->controls_rwsem);
 996         kctl = snd_ctl_find_id(card, &id);
 997         if (kctl == NULL) {
 998                 result = -ENOENT;
 999         } else {
1000                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1001                 if (vd->owner == NULL)
1002                         result = -EINVAL;
1003                 else if (vd->owner != file)
1004                         result = -EPERM;
1005                 else {
1006                         vd->owner = NULL;
1007                         result = 0;
1008                 }
1009         }
1010         up_write(&card->controls_rwsem);
1011         return result;
1012 }
1013
1014 struct user_element {
1015         struct snd_ctl_elem_info info;
1016         struct snd_card *card;
1017         char *elem_data;                /* element data */
1018         unsigned long elem_data_size;   /* size of element data in bytes */
1019         void *tlv_data;                 /* TLV data */
1020         unsigned long tlv_data_size;    /* TLV data size */
1021         void *priv_data;                /* private data (like strings for enumerated type) */
1022 };
1023
1024 static int snd_ctl_elem_user_info(struct snd_kcontrol *kcontrol,
1025                                   struct snd_ctl_elem_info *uinfo)
1026 {
1027         struct user_element *ue = kcontrol->private_data;
1028         unsigned int offset;
1029
1030         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1031         *uinfo = ue->info;
1032         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1033
1034         return 0;
1035 }
1036
1037 static int snd_ctl_elem_user_enum_info(struct snd_kcontrol *kcontrol,
1038                                        struct snd_ctl_elem_info *uinfo)
1039 {
1040         struct user_element *ue = kcontrol->private_data;
1041         const char *names;
1042         unsigned int item;
1043         unsigned int offset;
1044
1045         item = uinfo->value.enumerated.item;
1046
1047         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1048         *uinfo = ue->info;
1049         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1050
1051         item = min(item, uinfo->value.enumerated.items - 1);
1052         uinfo->value.enumerated.item = item;
1053
1054         names = ue->priv_data;
1055         for (; item > 0; --item)
1056                 names += strlen(names) + 1;
1057         strcpy(uinfo->value.enumerated.name, names);
1058
1059         return 0;
1060 }
1061
1062 static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
1063                                  struct snd_ctl_elem_value *ucontrol)
1064 {
1065         struct user_element *ue = kcontrol->private_data;
1066         unsigned int size = ue->elem_data_size;
1067         char *src = ue->elem_data +
1068                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1069
1070         memcpy(&ucontrol->value, src, size);
1071         return 0;
1072 }
1073
1074 static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
1075                                  struct snd_ctl_elem_value *ucontrol)
1076 {
1077         int change;
1078         struct user_element *ue = kcontrol->private_data;
1079         unsigned int size = ue->elem_data_size;
1080         char *dst = ue->elem_data +
1081                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1082
1083         change = memcmp(&ucontrol->value, dst, size) != 0;
1084         if (change)
1085                 memcpy(dst, &ucontrol->value, size);
1086         return change;
1087 }
1088
1089 static int replace_user_tlv(struct snd_kcontrol *kctl, unsigned int __user *buf,
1090                             unsigned int size)
1091 {
1092         struct user_element *ue = kctl->private_data;
1093         unsigned int *container;
1094         struct snd_ctl_elem_id id;
1095         unsigned int mask = 0;
1096         int i;
1097         int change;
1098
1099         if (size > 1024 * 128)  /* sane value */
1100                 return -EINVAL;
1101
1102         container = vmemdup_user(buf, size);
1103         if (IS_ERR(container))
1104                 return PTR_ERR(container);
1105
1106         change = ue->tlv_data_size != size;
1107         if (!change)
1108                 change = memcmp(ue->tlv_data, container, size) != 0;
1109         if (!change) {
1110                 kvfree(container);
1111                 return 0;
1112         }
1113
1114         if (ue->tlv_data == NULL) {
1115                 /* Now TLV data is available. */
1116                 for (i = 0; i < kctl->count; ++i)
1117                         kctl->vd[i].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
1118                 mask = SNDRV_CTL_EVENT_MASK_INFO;
1119         }
1120
1121         kvfree(ue->tlv_data);
1122         ue->tlv_data = container;
1123         ue->tlv_data_size = size;
1124
1125         mask |= SNDRV_CTL_EVENT_MASK_TLV;
1126         for (i = 0; i < kctl->count; ++i) {
1127                 snd_ctl_build_ioff(&id, kctl, i);
1128                 snd_ctl_notify(ue->card, mask, &id);
1129         }
1130
1131         return change;
1132 }
1133
1134 static int read_user_tlv(struct snd_kcontrol *kctl, unsigned int __user *buf,
1135                          unsigned int size)
1136 {
1137         struct user_element *ue = kctl->private_data;
1138
1139         if (ue->tlv_data_size == 0 || ue->tlv_data == NULL)
1140                 return -ENXIO;
1141
1142         if (size < ue->tlv_data_size)
1143                 return -ENOSPC;
1144
1145         if (copy_to_user(buf, ue->tlv_data, ue->tlv_data_size))
1146                 return -EFAULT;
1147
1148         return 0;
1149 }
1150
1151 static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kctl, int op_flag,
1152                                  unsigned int size, unsigned int __user *buf)
1153 {
1154         if (op_flag == SNDRV_CTL_TLV_OP_WRITE)
1155                 return replace_user_tlv(kctl, buf, size);
1156         else
1157                 return read_user_tlv(kctl, buf, size);
1158 }
1159
1160 static int snd_ctl_elem_init_enum_names(struct user_element *ue)
1161 {
1162         char *names, *p;
1163         size_t buf_len, name_len;
1164         unsigned int i;
1165         const uintptr_t user_ptrval = ue->info.value.enumerated.names_ptr;
1166
1167         if (ue->info.value.enumerated.names_length > 64 * 1024)
1168                 return -EINVAL;
1169
1170         names = vmemdup_user((const void __user *)user_ptrval,
1171                 ue->info.value.enumerated.names_length);
1172         if (IS_ERR(names))
1173                 return PTR_ERR(names);
1174
1175         /* check that there are enough valid names */
1176         buf_len = ue->info.value.enumerated.names_length;
1177         p = names;
1178         for (i = 0; i < ue->info.value.enumerated.items; ++i) {
1179                 name_len = strnlen(p, buf_len);
1180                 if (name_len == 0 || name_len >= 64 || name_len == buf_len) {
1181                         kvfree(names);
1182                         return -EINVAL;
1183                 }
1184                 p += name_len + 1;
1185                 buf_len -= name_len + 1;
1186         }
1187
1188         ue->priv_data = names;
1189         ue->info.value.enumerated.names_ptr = 0;
1190
1191         return 0;
1192 }
1193
1194 static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)
1195 {
1196         struct user_element *ue = kcontrol->private_data;
1197
1198         kvfree(ue->tlv_data);
1199         kvfree(ue->priv_data);
1200         kfree(ue);
1201 }
1202
1203 static int snd_ctl_elem_add(struct snd_ctl_file *file,
1204                             struct snd_ctl_elem_info *info, int replace)
1205 {
1206         /* The capacity of struct snd_ctl_elem_value.value.*/
1207         static const unsigned int value_sizes[] = {
1208                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = sizeof(long),
1209                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = sizeof(long),
1210                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = sizeof(unsigned int),
1211                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = sizeof(unsigned char),
1212                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = sizeof(struct snd_aes_iec958),
1213                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = sizeof(long long),
1214         };
1215         static const unsigned int max_value_counts[] = {
1216                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = 128,
1217                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = 128,
1218                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = 128,
1219                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = 512,
1220                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = 1,
1221                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = 64,
1222         };
1223         struct snd_card *card = file->card;
1224         struct snd_kcontrol *kctl;
1225         unsigned int count;
1226         unsigned int access;
1227         long private_size;
1228         struct user_element *ue;
1229         unsigned int offset;
1230         int err;
1231
1232         if (!*info->id.name)
1233                 return -EINVAL;
1234         if (strnlen(info->id.name, sizeof(info->id.name)) >= sizeof(info->id.name))
1235                 return -EINVAL;
1236
1237         /* Delete a control to replace them if needed. */
1238         if (replace) {
1239                 info->id.numid = 0;
1240                 err = snd_ctl_remove_user_ctl(file, &info->id);
1241                 if (err)
1242                         return err;
1243         }
1244
1245         /*
1246          * The number of userspace controls are counted control by control,
1247          * not element by element.
1248          */
1249         if (card->user_ctl_count + 1 > MAX_USER_CONTROLS)
1250                 return -ENOMEM;
1251
1252         /* Check the number of elements for this userspace control. */
1253         count = info->owner;
1254         if (count == 0)
1255                 count = 1;
1256
1257         /* Arrange access permissions if needed. */
1258         access = info->access;
1259         if (access == 0)
1260                 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
1261         access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
1262                    SNDRV_CTL_ELEM_ACCESS_INACTIVE |
1263                    SNDRV_CTL_ELEM_ACCESS_TLV_WRITE);
1264
1265         /* In initial state, nothing is available as TLV container. */
1266         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE)
1267                 access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
1268         access |= SNDRV_CTL_ELEM_ACCESS_USER;
1269
1270         /*
1271          * Check information and calculate the size of data specific to
1272          * this userspace control.
1273          */
1274         if (info->type < SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
1275             info->type > SNDRV_CTL_ELEM_TYPE_INTEGER64)
1276                 return -EINVAL;
1277         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED &&
1278             info->value.enumerated.items == 0)
1279                 return -EINVAL;
1280         if (info->count < 1 ||
1281             info->count > max_value_counts[info->type])
1282                 return -EINVAL;
1283         if (!validate_element_member_dimension(info))
1284                 return -EINVAL;
1285         private_size = value_sizes[info->type] * info->count;
1286
1287         /*
1288          * Keep memory object for this userspace control. After passing this
1289          * code block, the instance should be freed by snd_ctl_free_one().
1290          *
1291          * Note that these elements in this control are locked.
1292          */
1293         err = snd_ctl_new(&kctl, count, access, file);
1294         if (err < 0)
1295                 return err;
1296         memcpy(&kctl->id, &info->id, sizeof(kctl->id));
1297         kctl->private_data = kzalloc(sizeof(struct user_element) + private_size * count,
1298                                      GFP_KERNEL);
1299         if (kctl->private_data == NULL) {
1300                 kfree(kctl);
1301                 return -ENOMEM;
1302         }
1303         kctl->private_free = snd_ctl_elem_user_free;
1304
1305         /* Set private data for this userspace control. */
1306         ue = (struct user_element *)kctl->private_data;
1307         ue->card = card;
1308         ue->info = *info;
1309         ue->info.access = 0;
1310         ue->elem_data = (char *)ue + sizeof(*ue);
1311         ue->elem_data_size = private_size;
1312         if (ue->info.type == SNDRV_CTL_ELEM_TYPE_ENUMERATED) {
1313                 err = snd_ctl_elem_init_enum_names(ue);
1314                 if (err < 0) {
1315                         snd_ctl_free_one(kctl);
1316                         return err;
1317                 }
1318         }
1319
1320         /* Set callback functions. */
1321         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
1322                 kctl->info = snd_ctl_elem_user_enum_info;
1323         else
1324                 kctl->info = snd_ctl_elem_user_info;
1325         if (access & SNDRV_CTL_ELEM_ACCESS_READ)
1326                 kctl->get = snd_ctl_elem_user_get;
1327         if (access & SNDRV_CTL_ELEM_ACCESS_WRITE)
1328                 kctl->put = snd_ctl_elem_user_put;
1329         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE)
1330                 kctl->tlv.c = snd_ctl_elem_user_tlv;
1331
1332         /* This function manage to free the instance on failure. */
1333         down_write(&card->controls_rwsem);
1334         err = __snd_ctl_add_replace(card, kctl, CTL_ADD_EXCLUSIVE);
1335         if (err < 0) {
1336                 snd_ctl_free_one(kctl);
1337                 goto unlock;
1338         }
1339         offset = snd_ctl_get_ioff(kctl, &info->id);
1340         snd_ctl_build_ioff(&info->id, kctl, offset);
1341         /*
1342          * Here we cannot fill any field for the number of elements added by
1343          * this operation because there're no specific fields. The usage of
1344          * 'owner' field for this purpose may cause any bugs to userspace
1345          * applications because the field originally means PID of a process
1346          * which locks the element.
1347          */
1348
1349         card->user_ctl_count++;
1350
1351  unlock:
1352         up_write(&card->controls_rwsem);
1353         return 0;
1354 }
1355
1356 static int snd_ctl_elem_add_user(struct snd_ctl_file *file,
1357                                  struct snd_ctl_elem_info __user *_info, int replace)
1358 {
1359         struct snd_ctl_elem_info info;
1360         int err;
1361
1362         if (copy_from_user(&info, _info, sizeof(info)))
1363                 return -EFAULT;
1364         err = snd_ctl_elem_add(file, &info, replace);
1365         if (err < 0)
1366                 return err;
1367         if (copy_to_user(_info, &info, sizeof(info))) {
1368                 snd_ctl_remove_user_ctl(file, &info.id);
1369                 return -EFAULT;
1370         }
1371
1372         return 0;
1373 }
1374
1375 static int snd_ctl_elem_remove(struct snd_ctl_file *file,
1376                                struct snd_ctl_elem_id __user *_id)
1377 {
1378         struct snd_ctl_elem_id id;
1379
1380         if (copy_from_user(&id, _id, sizeof(id)))
1381                 return -EFAULT;
1382         return snd_ctl_remove_user_ctl(file, &id);
1383 }
1384
1385 static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
1386 {
1387         int subscribe;
1388         if (get_user(subscribe, ptr))
1389                 return -EFAULT;
1390         if (subscribe < 0) {
1391                 subscribe = file->subscribed;
1392                 if (put_user(subscribe, ptr))
1393                         return -EFAULT;
1394                 return 0;
1395         }
1396         if (subscribe) {
1397                 file->subscribed = 1;
1398                 return 0;
1399         } else if (file->subscribed) {
1400                 snd_ctl_empty_read_queue(file);
1401                 file->subscribed = 0;
1402         }
1403         return 0;
1404 }
1405
1406 static int call_tlv_handler(struct snd_ctl_file *file, int op_flag,
1407                             struct snd_kcontrol *kctl,
1408                             struct snd_ctl_elem_id *id,
1409                             unsigned int __user *buf, unsigned int size)
1410 {
1411         static const struct {
1412                 int op;
1413                 int perm;
1414         } pairs[] = {
1415                 {SNDRV_CTL_TLV_OP_READ,  SNDRV_CTL_ELEM_ACCESS_TLV_READ},
1416                 {SNDRV_CTL_TLV_OP_WRITE, SNDRV_CTL_ELEM_ACCESS_TLV_WRITE},
1417                 {SNDRV_CTL_TLV_OP_CMD,   SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND},
1418         };
1419         struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)];
1420         int i;
1421
1422         /* Check support of the request for this element. */
1423         for (i = 0; i < ARRAY_SIZE(pairs); ++i) {
1424                 if (op_flag == pairs[i].op && (vd->access & pairs[i].perm))
1425                         break;
1426         }
1427         if (i == ARRAY_SIZE(pairs))
1428                 return -ENXIO;
1429
1430         if (kctl->tlv.c == NULL)
1431                 return -ENXIO;
1432
1433         /* When locked, this is unavailable. */
1434         if (vd->owner != NULL && vd->owner != file)
1435                 return -EPERM;
1436
1437         return kctl->tlv.c(kctl, op_flag, size, buf);
1438 }
1439
1440 static int read_tlv_buf(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id,
1441                         unsigned int __user *buf, unsigned int size)
1442 {
1443         struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)];
1444         unsigned int len;
1445
1446         if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ))
1447                 return -ENXIO;
1448
1449         if (kctl->tlv.p == NULL)
1450                 return -ENXIO;
1451
1452         len = sizeof(unsigned int) * 2 + kctl->tlv.p[1];
1453         if (size < len)
1454                 return -ENOMEM;
1455
1456         if (copy_to_user(buf, kctl->tlv.p, len))
1457                 return -EFAULT;
1458
1459         return 0;
1460 }
1461
1462 static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
1463                              struct snd_ctl_tlv __user *buf,
1464                              int op_flag)
1465 {
1466         struct snd_ctl_tlv header;
1467         unsigned int __user *container;
1468         unsigned int container_size;
1469         struct snd_kcontrol *kctl;
1470         struct snd_ctl_elem_id id;
1471         struct snd_kcontrol_volatile *vd;
1472
1473         if (copy_from_user(&header, buf, sizeof(header)))
1474                 return -EFAULT;
1475
1476         /* In design of control core, numerical ID starts at 1. */
1477         if (header.numid == 0)
1478                 return -EINVAL;
1479
1480         /* At least, container should include type and length fields.  */
1481         if (header.length < sizeof(unsigned int) * 2)
1482                 return -EINVAL;
1483         container_size = header.length;
1484         container = buf->tlv;
1485
1486         kctl = snd_ctl_find_numid(file->card, header.numid);
1487         if (kctl == NULL)
1488                 return -ENOENT;
1489
1490         /* Calculate index of the element in this set. */
1491         id = kctl->id;
1492         snd_ctl_build_ioff(&id, kctl, header.numid - id.numid);
1493         vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1494
1495         if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
1496                 return call_tlv_handler(file, op_flag, kctl, &id, container,
1497                                         container_size);
1498         } else {
1499                 if (op_flag == SNDRV_CTL_TLV_OP_READ) {
1500                         return read_tlv_buf(kctl, &id, container,
1501                                             container_size);
1502                 }
1503         }
1504
1505         /* Not supported. */
1506         return -ENXIO;
1507 }
1508
1509 static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1510 {
1511         struct snd_ctl_file *ctl;
1512         struct snd_card *card;
1513         struct snd_kctl_ioctl *p;
1514         void __user *argp = (void __user *)arg;
1515         int __user *ip = argp;
1516         int err;
1517
1518         ctl = file->private_data;
1519         card = ctl->card;
1520         if (snd_BUG_ON(!card))
1521                 return -ENXIO;
1522         switch (cmd) {
1523         case SNDRV_CTL_IOCTL_PVERSION:
1524                 return put_user(SNDRV_CTL_VERSION, ip) ? -EFAULT : 0;
1525         case SNDRV_CTL_IOCTL_CARD_INFO:
1526                 return snd_ctl_card_info(card, ctl, cmd, argp);
1527         case SNDRV_CTL_IOCTL_ELEM_LIST:
1528                 return snd_ctl_elem_list(card, argp);
1529         case SNDRV_CTL_IOCTL_ELEM_INFO:
1530                 return snd_ctl_elem_info_user(ctl, argp);
1531         case SNDRV_CTL_IOCTL_ELEM_READ:
1532                 return snd_ctl_elem_read_user(card, argp);
1533         case SNDRV_CTL_IOCTL_ELEM_WRITE:
1534                 return snd_ctl_elem_write_user(ctl, argp);
1535         case SNDRV_CTL_IOCTL_ELEM_LOCK:
1536                 return snd_ctl_elem_lock(ctl, argp);
1537         case SNDRV_CTL_IOCTL_ELEM_UNLOCK:
1538                 return snd_ctl_elem_unlock(ctl, argp);
1539         case SNDRV_CTL_IOCTL_ELEM_ADD:
1540                 return snd_ctl_elem_add_user(ctl, argp, 0);
1541         case SNDRV_CTL_IOCTL_ELEM_REPLACE:
1542                 return snd_ctl_elem_add_user(ctl, argp, 1);
1543         case SNDRV_CTL_IOCTL_ELEM_REMOVE:
1544                 return snd_ctl_elem_remove(ctl, argp);
1545         case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
1546                 return snd_ctl_subscribe_events(ctl, ip);
1547         case SNDRV_CTL_IOCTL_TLV_READ:
1548                 down_read(&ctl->card->controls_rwsem);
1549                 err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_READ);
1550                 up_read(&ctl->card->controls_rwsem);
1551                 return err;
1552         case SNDRV_CTL_IOCTL_TLV_WRITE:
1553                 down_write(&ctl->card->controls_rwsem);
1554                 err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_WRITE);
1555                 up_write(&ctl->card->controls_rwsem);
1556                 return err;
1557         case SNDRV_CTL_IOCTL_TLV_COMMAND:
1558                 down_write(&ctl->card->controls_rwsem);
1559                 err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_CMD);
1560                 up_write(&ctl->card->controls_rwsem);
1561                 return err;
1562         case SNDRV_CTL_IOCTL_POWER:
1563                 return -ENOPROTOOPT;
1564         case SNDRV_CTL_IOCTL_POWER_STATE:
1565 #ifdef CONFIG_PM
1566                 return put_user(card->power_state, ip) ? -EFAULT : 0;
1567 #else
1568                 return put_user(SNDRV_CTL_POWER_D0, ip) ? -EFAULT : 0;
1569 #endif
1570         }
1571         down_read(&snd_ioctl_rwsem);
1572         list_for_each_entry(p, &snd_control_ioctls, list) {
1573                 err = p->fioctl(card, ctl, cmd, arg);
1574                 if (err != -ENOIOCTLCMD) {
1575                         up_read(&snd_ioctl_rwsem);
1576                         return err;
1577                 }
1578         }
1579         up_read(&snd_ioctl_rwsem);
1580         dev_dbg(card->dev, "unknown ioctl = 0x%x\n", cmd);
1581         return -ENOTTY;
1582 }
1583
1584 static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
1585                             size_t count, loff_t * offset)
1586 {
1587         struct snd_ctl_file *ctl;
1588         int err = 0;
1589         ssize_t result = 0;
1590
1591         ctl = file->private_data;
1592         if (snd_BUG_ON(!ctl || !ctl->card))
1593                 return -ENXIO;
1594         if (!ctl->subscribed)
1595                 return -EBADFD;
1596         if (count < sizeof(struct snd_ctl_event))
1597                 return -EINVAL;
1598         spin_lock_irq(&ctl->read_lock);
1599         while (count >= sizeof(struct snd_ctl_event)) {
1600                 struct snd_ctl_event ev;
1601                 struct snd_kctl_event *kev;
1602                 while (list_empty(&ctl->events)) {
1603                         wait_queue_entry_t wait;
1604                         if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
1605                                 err = -EAGAIN;
1606                                 goto __end_lock;
1607                         }
1608                         init_waitqueue_entry(&wait, current);
1609                         add_wait_queue(&ctl->change_sleep, &wait);
1610                         set_current_state(TASK_INTERRUPTIBLE);
1611                         spin_unlock_irq(&ctl->read_lock);
1612                         schedule();
1613                         remove_wait_queue(&ctl->change_sleep, &wait);
1614                         if (ctl->card->shutdown)
1615                                 return -ENODEV;
1616                         if (signal_pending(current))
1617                                 return -ERESTARTSYS;
1618                         spin_lock_irq(&ctl->read_lock);
1619                 }
1620                 kev = snd_kctl_event(ctl->events.next);
1621                 ev.type = SNDRV_CTL_EVENT_ELEM;
1622                 ev.data.elem.mask = kev->mask;
1623                 ev.data.elem.id = kev->id;
1624                 list_del(&kev->list);
1625                 spin_unlock_irq(&ctl->read_lock);
1626                 kfree(kev);
1627                 if (copy_to_user(buffer, &ev, sizeof(struct snd_ctl_event))) {
1628                         err = -EFAULT;
1629                         goto __end;
1630                 }
1631                 spin_lock_irq(&ctl->read_lock);
1632                 buffer += sizeof(struct snd_ctl_event);
1633                 count -= sizeof(struct snd_ctl_event);
1634                 result += sizeof(struct snd_ctl_event);
1635         }
1636       __end_lock:
1637         spin_unlock_irq(&ctl->read_lock);
1638       __end:
1639         return result > 0 ? result : err;
1640 }
1641
1642 static __poll_t snd_ctl_poll(struct file *file, poll_table * wait)
1643 {
1644         __poll_t mask;
1645         struct snd_ctl_file *ctl;
1646
1647         ctl = file->private_data;
1648         if (!ctl->subscribed)
1649                 return 0;
1650         poll_wait(file, &ctl->change_sleep, wait);
1651
1652         mask = 0;
1653         if (!list_empty(&ctl->events))
1654                 mask |= EPOLLIN | EPOLLRDNORM;
1655
1656         return mask;
1657 }
1658
1659 /*
1660  * register the device-specific control-ioctls.
1661  * called from each device manager like pcm.c, hwdep.c, etc.
1662  */
1663 static int _snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn, struct list_head *lists)
1664 {
1665         struct snd_kctl_ioctl *pn;
1666
1667         pn = kzalloc(sizeof(struct snd_kctl_ioctl), GFP_KERNEL);
1668         if (pn == NULL)
1669                 return -ENOMEM;
1670         pn->fioctl = fcn;
1671         down_write(&snd_ioctl_rwsem);
1672         list_add_tail(&pn->list, lists);
1673         up_write(&snd_ioctl_rwsem);
1674         return 0;
1675 }
1676
1677 /**
1678  * snd_ctl_register_ioctl - register the device-specific control-ioctls
1679  * @fcn: ioctl callback function
1680  *
1681  * called from each device manager like pcm.c, hwdep.c, etc.
1682  */
1683 int snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn)
1684 {
1685         return _snd_ctl_register_ioctl(fcn, &snd_control_ioctls);
1686 }
1687 EXPORT_SYMBOL(snd_ctl_register_ioctl);
1688
1689 #ifdef CONFIG_COMPAT
1690 /**
1691  * snd_ctl_register_ioctl_compat - register the device-specific 32bit compat
1692  * control-ioctls
1693  * @fcn: ioctl callback function
1694  */
1695 int snd_ctl_register_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1696 {
1697         return _snd_ctl_register_ioctl(fcn, &snd_control_compat_ioctls);
1698 }
1699 EXPORT_SYMBOL(snd_ctl_register_ioctl_compat);
1700 #endif
1701
1702 /*
1703  * de-register the device-specific control-ioctls.
1704  */
1705 static int _snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn,
1706                                      struct list_head *lists)
1707 {
1708         struct snd_kctl_ioctl *p;
1709
1710         if (snd_BUG_ON(!fcn))
1711                 return -EINVAL;
1712         down_write(&snd_ioctl_rwsem);
1713         list_for_each_entry(p, lists, list) {
1714                 if (p->fioctl == fcn) {
1715                         list_del(&p->list);
1716                         up_write(&snd_ioctl_rwsem);
1717                         kfree(p);
1718                         return 0;
1719                 }
1720         }
1721         up_write(&snd_ioctl_rwsem);
1722         snd_BUG();
1723         return -EINVAL;
1724 }
1725
1726 /**
1727  * snd_ctl_unregister_ioctl - de-register the device-specific control-ioctls
1728  * @fcn: ioctl callback function to unregister
1729  */
1730 int snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn)
1731 {
1732         return _snd_ctl_unregister_ioctl(fcn, &snd_control_ioctls);
1733 }
1734 EXPORT_SYMBOL(snd_ctl_unregister_ioctl);
1735
1736 #ifdef CONFIG_COMPAT
1737 /**
1738  * snd_ctl_unregister_ioctl - de-register the device-specific compat 32bit
1739  * control-ioctls
1740  * @fcn: ioctl callback function to unregister
1741  */
1742 int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1743 {
1744         return _snd_ctl_unregister_ioctl(fcn, &snd_control_compat_ioctls);
1745 }
1746 EXPORT_SYMBOL(snd_ctl_unregister_ioctl_compat);
1747 #endif
1748
1749 static int snd_ctl_fasync(int fd, struct file * file, int on)
1750 {
1751         struct snd_ctl_file *ctl;
1752
1753         ctl = file->private_data;
1754         return fasync_helper(fd, file, on, &ctl->fasync);
1755 }
1756
1757 /* return the preferred subdevice number if already assigned;
1758  * otherwise return -1
1759  */
1760 int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type)
1761 {
1762         struct snd_ctl_file *kctl;
1763         int subdevice = -1;
1764
1765         read_lock(&card->ctl_files_rwlock);
1766         list_for_each_entry(kctl, &card->ctl_files, list) {
1767                 if (kctl->pid == task_pid(current)) {
1768                         subdevice = kctl->preferred_subdevice[type];
1769                         if (subdevice != -1)
1770                                 break;
1771                 }
1772         }
1773         read_unlock(&card->ctl_files_rwlock);
1774         return subdevice;
1775 }
1776 EXPORT_SYMBOL_GPL(snd_ctl_get_preferred_subdevice);
1777
1778 /*
1779  * ioctl32 compat
1780  */
1781 #ifdef CONFIG_COMPAT
1782 #include "control_compat.c"
1783 #else
1784 #define snd_ctl_ioctl_compat    NULL
1785 #endif
1786
1787 /*
1788  *  INIT PART
1789  */
1790
1791 static const struct file_operations snd_ctl_f_ops =
1792 {
1793         .owner =        THIS_MODULE,
1794         .read =         snd_ctl_read,
1795         .open =         snd_ctl_open,
1796         .release =      snd_ctl_release,
1797         .llseek =       no_llseek,
1798         .poll =         snd_ctl_poll,
1799         .unlocked_ioctl =       snd_ctl_ioctl,
1800         .compat_ioctl = snd_ctl_ioctl_compat,
1801         .fasync =       snd_ctl_fasync,
1802 };
1803
1804 /*
1805  * registration of the control device
1806  */
1807 static int snd_ctl_dev_register(struct snd_device *device)
1808 {
1809         struct snd_card *card = device->device_data;
1810
1811         return snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
1812                                    &snd_ctl_f_ops, card, &card->ctl_dev);
1813 }
1814
1815 /*
1816  * disconnection of the control device
1817  */
1818 static int snd_ctl_dev_disconnect(struct snd_device *device)
1819 {
1820         struct snd_card *card = device->device_data;
1821         struct snd_ctl_file *ctl;
1822
1823         read_lock(&card->ctl_files_rwlock);
1824         list_for_each_entry(ctl, &card->ctl_files, list) {
1825                 wake_up(&ctl->change_sleep);
1826                 kill_fasync(&ctl->fasync, SIGIO, POLL_ERR);
1827         }
1828         read_unlock(&card->ctl_files_rwlock);
1829
1830         return snd_unregister_device(&card->ctl_dev);
1831 }
1832
1833 /*
1834  * free all controls
1835  */
1836 static int snd_ctl_dev_free(struct snd_device *device)
1837 {
1838         struct snd_card *card = device->device_data;
1839         struct snd_kcontrol *control;
1840
1841         down_write(&card->controls_rwsem);
1842         while (!list_empty(&card->controls)) {
1843                 control = snd_kcontrol(card->controls.next);
1844                 snd_ctl_remove(card, control);
1845         }
1846         up_write(&card->controls_rwsem);
1847         put_device(&card->ctl_dev);
1848         return 0;
1849 }
1850
1851 /*
1852  * create control core:
1853  * called from init.c
1854  */
1855 int snd_ctl_create(struct snd_card *card)
1856 {
1857         static struct snd_device_ops ops = {
1858                 .dev_free = snd_ctl_dev_free,
1859                 .dev_register = snd_ctl_dev_register,
1860                 .dev_disconnect = snd_ctl_dev_disconnect,
1861         };
1862         int err;
1863
1864         if (snd_BUG_ON(!card))
1865                 return -ENXIO;
1866         if (snd_BUG_ON(card->number < 0 || card->number >= SNDRV_CARDS))
1867                 return -ENXIO;
1868
1869         snd_device_initialize(&card->ctl_dev, card);
1870         dev_set_name(&card->ctl_dev, "controlC%d", card->number);
1871
1872         err = snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
1873         if (err < 0)
1874                 put_device(&card->ctl_dev);
1875         return err;
1876 }
1877
1878 /*
1879  * Frequently used control callbacks/helpers
1880  */
1881
1882 /**
1883  * snd_ctl_boolean_mono_info - Helper function for a standard boolean info
1884  * callback with a mono channel
1885  * @kcontrol: the kcontrol instance
1886  * @uinfo: info to store
1887  *
1888  * This is a function that can be used as info callback for a standard
1889  * boolean control with a single mono channel.
1890  */
1891 int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
1892                               struct snd_ctl_elem_info *uinfo)
1893 {
1894         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1895         uinfo->count = 1;
1896         uinfo->value.integer.min = 0;
1897         uinfo->value.integer.max = 1;
1898         return 0;
1899 }
1900 EXPORT_SYMBOL(snd_ctl_boolean_mono_info);
1901
1902 /**
1903  * snd_ctl_boolean_stereo_info - Helper function for a standard boolean info
1904  * callback with stereo two channels
1905  * @kcontrol: the kcontrol instance
1906  * @uinfo: info to store
1907  *
1908  * This is a function that can be used as info callback for a standard
1909  * boolean control with stereo two channels.
1910  */
1911 int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
1912                                 struct snd_ctl_elem_info *uinfo)
1913 {
1914         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1915         uinfo->count = 2;
1916         uinfo->value.integer.min = 0;
1917         uinfo->value.integer.max = 1;
1918         return 0;
1919 }
1920 EXPORT_SYMBOL(snd_ctl_boolean_stereo_info);
1921
1922 /**
1923  * snd_ctl_enum_info - fills the info structure for an enumerated control
1924  * @info: the structure to be filled
1925  * @channels: the number of the control's channels; often one
1926  * @items: the number of control values; also the size of @names
1927  * @names: an array containing the names of all control values
1928  *
1929  * Sets all required fields in @info to their appropriate values.
1930  * If the control's accessibility is not the default (readable and writable),
1931  * the caller has to fill @info->access.
1932  *
1933  * Return: Zero.
1934  */
1935 int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
1936                       unsigned int items, const char *const names[])
1937 {
1938         info->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
1939         info->count = channels;
1940         info->value.enumerated.items = items;
1941         if (!items)
1942                 return 0;
1943         if (info->value.enumerated.item >= items)
1944                 info->value.enumerated.item = items - 1;
1945         WARN(strlen(names[info->value.enumerated.item]) >= sizeof(info->value.enumerated.name),
1946              "ALSA: too long item name '%s'\n",
1947              names[info->value.enumerated.item]);
1948         strlcpy(info->value.enumerated.name,
1949                 names[info->value.enumerated.item],
1950                 sizeof(info->value.enumerated.name));
1951         return 0;
1952 }
1953 EXPORT_SYMBOL(snd_ctl_enum_info);