sound/core/control.c

   1 /*
   2  *  Routines for driver control interface
   3  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
   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/sched/signal.h>
  29 #include <sound/core.h>
  30 #include <sound/minors.h>
  31 #include <sound/info.h>
  32 #include <sound/control.h>
  33
  34 /* max number of user-defined controls */
  35 #define MAX_USER_CONTROLS       32
  36 #define MAX_CONTROL_COUNT       1028
  37
  38 struct snd_kctl_ioctl {
  39         struct list_head list;          /* list of all ioctls */
  40         snd_kctl_ioctl_func_t fioctl;
  41 };
  42
  43 static DECLARE_RWSEM(snd_ioctl_rwsem);
  44 static LIST_HEAD(snd_control_ioctls);
  45 #ifdef CONFIG_COMPAT
  46 static LIST_HEAD(snd_control_compat_ioctls);
  47 #endif
  48
  49 static int snd_ctl_open(struct inode *inode, struct file *file)
  50 {
  51         unsigned long flags;
  52         struct snd_card *card;
  53         struct snd_ctl_file *ctl;
  54         int i, err;
  55
  56         err = nonseekable_open(inode, file);
  57         if (err < 0)
  58                 return err;
  59
  60         card = snd_lookup_minor_data(iminor(inode), SNDRV_DEVICE_TYPE_CONTROL);
  61         if (!card) {
  62                 err = -ENODEV;
  63                 goto __error1;
  64         }
  65         err = snd_card_file_add(card, file);
  66         if (err < 0) {
  67                 err = -ENODEV;
  68                 goto __error1;
  69         }
  70         if (!try_module_get(card->module)) {
  71                 err = -EFAULT;
  72                 goto __error2;
  73         }
  74         ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);
  75         if (ctl == NULL) {
  76                 err = -ENOMEM;
  77                 goto __error;
  78         }
  79         INIT_LIST_HEAD(&ctl->events);
  80         init_waitqueue_head(&ctl->change_sleep);
  81         spin_lock_init(&ctl->read_lock);
  82         ctl->card = card;
  83         for (i = 0; i < SND_CTL_SUBDEV_ITEMS; i++)
  84                 ctl->preferred_subdevice[i] = -1;
  85         ctl->pid = get_pid(task_pid(current));
  86         file->private_data = ctl;
  87         write_lock_irqsave(&card->ctl_files_rwlock, flags);
  88         list_add_tail(&ctl->list, &card->ctl_files);
  89         write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
  90         snd_card_unref(card);
  91         return 0;
  92
  93       __error:
  94         module_put(card->module);
  95       __error2:
  96         snd_card_file_remove(card, file);
  97       __error1:
  98         if (card)
  99                 snd_card_unref(card);
 100         return err;
 101 }
 102
 103 static void snd_ctl_empty_read_queue(struct snd_ctl_file * ctl)
 104 {
 105         unsigned long flags;
 106         struct snd_kctl_event *cread;
 107
 108         spin_lock_irqsave(&ctl->read_lock, flags);
 109         while (!list_empty(&ctl->events)) {
 110                 cread = snd_kctl_event(ctl->events.next);
 111                 list_del(&cread->list);
 112                 kfree(cread);
 113         }
 114         spin_unlock_irqrestore(&ctl->read_lock, flags);
 115 }
 116
 117 static int snd_ctl_release(struct inode *inode, struct file *file)
 118 {
 119         unsigned long flags;
 120         struct snd_card *card;
 121         struct snd_ctl_file *ctl;
 122         struct snd_kcontrol *control;
 123         unsigned int idx;
 124
 125         ctl = file->private_data;
 126         file->private_data = NULL;
 127         card = ctl->card;
 128         write_lock_irqsave(&card->ctl_files_rwlock, flags);
 129         list_del(&ctl->list);
 130         write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
 131         down_write(&card->controls_rwsem);
 132         list_for_each_entry(control, &card->controls, list)
 133                 for (idx = 0; idx < control->count; idx++)
 134                         if (control->vd[idx].owner == ctl)
 135                                 control->vd[idx].owner = NULL;
 136         up_write(&card->controls_rwsem);
 137         snd_ctl_empty_read_queue(ctl);
 138         put_pid(ctl->pid);
 139         kfree(ctl);
 140         module_put(card->module);
 141         snd_card_file_remove(card, file);
 142         return 0;
 143 }
 144
 145 /**
 146  * snd_ctl_notify - Send notification to user-space for a control change
 147  * @card: the card to send notification
 148  * @mask: the event mask, SNDRV_CTL_EVENT_*
 149  * @id: the ctl element id to send notification
 150  *
 151  * This function adds an event record with the given id and mask, appends
 152  * to the list and wakes up the user-space for notification.  This can be
 153  * called in the atomic context.
 154  */
 155 void snd_ctl_notify(struct snd_card *card, unsigned int mask,
 156                     struct snd_ctl_elem_id *id)
 157 {
 158         unsigned long flags;
 159         struct snd_ctl_file *ctl;
 160         struct snd_kctl_event *ev;
 161
 162         if (snd_BUG_ON(!card || !id))
 163                 return;
 164         if (card->shutdown)
 165                 return;
 166         read_lock(&card->ctl_files_rwlock);
 167 #if IS_ENABLED(CONFIG_SND_MIXER_OSS)
 168         card->mixer_oss_change_count++;
 169 #endif
 170         list_for_each_entry(ctl, &card->ctl_files, list) {
 171                 if (!ctl->subscribed)
 172                         continue;
 173                 spin_lock_irqsave(&ctl->read_lock, flags);
 174                 list_for_each_entry(ev, &ctl->events, list) {
 175                         if (ev->id.numid == id->numid) {
 176                                 ev->mask |= mask;
 177                                 goto _found;
 178                         }
 179                 }
 180                 ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
 181                 if (ev) {
 182                         ev->id = *id;
 183                         ev->mask = mask;
 184                         list_add_tail(&ev->list, &ctl->events);
 185                 } else {
 186                         dev_err(card->dev, "No memory available to allocate event\n");
 187                 }
 188         _found:
 189                 wake_up(&ctl->change_sleep);
 190                 spin_unlock_irqrestore(&ctl->read_lock, flags);
 191                 kill_fasync(&ctl->fasync, SIGIO, POLL_IN);
 192         }
 193         read_unlock(&card->ctl_files_rwlock);
 194 }
 195 EXPORT_SYMBOL(snd_ctl_notify);
 196
 197 /**
 198  * snd_ctl_new - create a new control instance with some elements
 199  * @kctl: the pointer to store new control instance
 200  * @count: the number of elements in this control
 201  * @access: the default access flags for elements in this control
 202  * @file: given when locking these elements
 203  *
 204  * Allocates a memory object for a new control instance. The instance has
 205  * elements as many as the given number (@count). Each element has given
 206  * access permissions (@access). Each element is locked when @file is given.
 207  *
 208  * Return: 0 on success, error code on failure
 209  */
 210 static int snd_ctl_new(struct snd_kcontrol **kctl, unsigned int count,
 211                        unsigned int access, struct snd_ctl_file *file)
 212 {
 213         unsigned int size;
 214         unsigned int idx;
 215
 216         if (count == 0 || count > MAX_CONTROL_COUNT)
 217                 return -EINVAL;
 218
 219         size  = sizeof(struct snd_kcontrol);
 220         size += sizeof(struct snd_kcontrol_volatile) * count;
 221
 222         *kctl = kzalloc(size, GFP_KERNEL);
 223         if (!*kctl)
 224                 return -ENOMEM;
 225
 226         for (idx = 0; idx < count; idx++) {
 227                 (*kctl)->vd[idx].access = access;
 228                 (*kctl)->vd[idx].owner = file;
 229         }
 230         (*kctl)->count = count;
 231
 232         return 0;
 233 }
 234
 235 /**
 236  * snd_ctl_new1 - create a control instance from the template
 237  * @ncontrol: the initialization record
 238  * @private_data: the private data to set
 239  *
 240  * Allocates a new struct snd_kcontrol instance and initialize from the given
 241  * template.  When the access field of ncontrol is 0, it's assumed as
 242  * READWRITE access. When the count field is 0, it's assumes as one.
 243  *
 244  * Return: The pointer of the newly generated instance, or %NULL on failure.
 245  */
 246 struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new *ncontrol,
 247                                   void *private_data)
 248 {
 249         struct snd_kcontrol *kctl;
 250         unsigned int count;
 251         unsigned int access;
 252         int err;
 253
 254         if (snd_BUG_ON(!ncontrol || !ncontrol->info))
 255                 return NULL;
 256
 257         count = ncontrol->count;
 258         if (count == 0)
 259                 count = 1;
 260
 261         access = ncontrol->access;
 262         if (access == 0)
 263                 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
 264         access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
 265                    SNDRV_CTL_ELEM_ACCESS_VOLATILE |
 266                    SNDRV_CTL_ELEM_ACCESS_INACTIVE |
 267                    SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE |
 268                    SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND |
 269                    SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
 270
 271         err = snd_ctl_new(&kctl, count, access, NULL);
 272         if (err < 0)
 273                 return NULL;
 274
 275         /* The 'numid' member is decided when calling snd_ctl_add(). */
 276         kctl->id.iface = ncontrol->iface;
 277         kctl->id.device = ncontrol->device;
 278         kctl->id.subdevice = ncontrol->subdevice;
 279         if (ncontrol->name) {
 280                 strlcpy(kctl->id.name, ncontrol->name, sizeof(kctl->id.name));
 281                 if (strcmp(ncontrol->name, kctl->id.name) != 0)
 282                         pr_warn("ALSA: Control name '%s' truncated to '%s'\n",
 283                                 ncontrol->name, kctl->id.name);
 284         }
 285         kctl->id.index = ncontrol->index;
 286
 287         kctl->info = ncontrol->info;
 288         kctl->get = ncontrol->get;
 289         kctl->put = ncontrol->put;
 290         kctl->tlv.p = ncontrol->tlv.p;
 291
 292         kctl->private_value = ncontrol->private_value;
 293         kctl->private_data = private_data;
 294
 295         return kctl;
 296 }
 297 EXPORT_SYMBOL(snd_ctl_new1);
 298
 299 /**
 300  * snd_ctl_free_one - release the control instance
 301  * @kcontrol: the control instance
 302  *
 303  * Releases the control instance created via snd_ctl_new()
 304  * or snd_ctl_new1().
 305  * Don't call this after the control was added to the card.
 306  */
 307 void snd_ctl_free_one(struct snd_kcontrol *kcontrol)
 308 {
 309         if (kcontrol) {
 310                 if (kcontrol->private_free)
 311                         kcontrol->private_free(kcontrol);
 312                 kfree(kcontrol);
 313         }
 314 }
 315 EXPORT_SYMBOL(snd_ctl_free_one);
 316
 317 static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
 318                                           unsigned int count)
 319 {
 320         struct snd_kcontrol *kctl;
 321
 322         /* Make sure that the ids assigned to the control do not wrap around */
 323         if (card->last_numid >= UINT_MAX - count)
 324                 card->last_numid = 0;
 325
 326         list_for_each_entry(kctl, &card->controls, list) {
 327                 if (kctl->id.numid < card->last_numid + 1 + count &&
 328                     kctl->id.numid + kctl->count > card->last_numid + 1) {
 329                         card->last_numid = kctl->id.numid + kctl->count - 1;
 330                         return true;
 331                 }
 332         }
 333         return false;
 334 }
 335
 336 static int snd_ctl_find_hole(struct snd_card *card, unsigned int count)
 337 {
 338         unsigned int iter = 100000;
 339
 340         while (snd_ctl_remove_numid_conflict(card, count)) {
 341                 if (--iter == 0) {
 342                         /* this situation is very unlikely */
 343                         dev_err(card->dev, "unable to allocate new control numid\n");
 344                         return -ENOMEM;
 345                 }
 346         }
 347         return 0;
 348 }
 349
 350 /**
 351  * snd_ctl_add - add the control instance to the card
 352  * @card: the card instance
 353  * @kcontrol: the control instance to add
 354  *
 355  * Adds the control instance created via snd_ctl_new() or
 356  * snd_ctl_new1() to the given card. Assigns also an unique
 357  * numid used for fast search.
 358  *
 359  * It frees automatically the control which cannot be added.
 360  *
 361  * Return: Zero if successful, or a negative error code on failure.
 362  *
 363  */
 364 int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
 365 {
 366         struct snd_ctl_elem_id id;
 367         unsigned int idx;
 368         unsigned int count;
 369         int err = -EINVAL;
 370
 371         if (! kcontrol)
 372                 return err;
 373         if (snd_BUG_ON(!card || !kcontrol->info))
 374                 goto error;
 375         id = kcontrol->id;
 376         if (id.index > UINT_MAX - kcontrol->count)
 377                 goto error;
 378
 379         down_write(&card->controls_rwsem);
 380         if (snd_ctl_find_id(card, &id)) {
 381                 up_write(&card->controls_rwsem);
 382                 dev_err(card->dev, "control %i:%i:%i:%s:%i is already present\n",
 383                                         id.iface,
 384                                         id.device,
 385                                         id.subdevice,
 386                                         id.name,
 387                                         id.index);
 388                 err = -EBUSY;
 389                 goto error;
 390         }
 391         if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
 392                 up_write(&card->controls_rwsem);
 393                 err = -ENOMEM;
 394                 goto error;
 395         }
 396         list_add_tail(&kcontrol->list, &card->controls);
 397         card->controls_count += kcontrol->count;
 398         kcontrol->id.numid = card->last_numid + 1;
 399         card->last_numid += kcontrol->count;
 400         id = kcontrol->id;
 401         count = kcontrol->count;
 402         up_write(&card->controls_rwsem);
 403         for (idx = 0; idx < count; idx++, id.index++, id.numid++)
 404                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
 405         return 0;
 406
 407  error:
 408         snd_ctl_free_one(kcontrol);
 409         return err;
 410 }
 411 EXPORT_SYMBOL(snd_ctl_add);
 412
 413 /**
 414  * snd_ctl_replace - replace the control instance of the card
 415  * @card: the card instance
 416  * @kcontrol: the control instance to replace
 417  * @add_on_replace: add the control if not already added
 418  *
 419  * Replaces the given control.  If the given control does not exist
 420  * and the add_on_replace flag is set, the control is added.  If the
 421  * control exists, it is destroyed first.
 422  *
 423  * It frees automatically the control which cannot be added or replaced.
 424  *
 425  * Return: Zero if successful, or a negative error code on failure.
 426  */
 427 int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
 428                     bool add_on_replace)
 429 {
 430         struct snd_ctl_elem_id id;
 431         unsigned int count;
 432         unsigned int idx;
 433         struct snd_kcontrol *old;
 434         int ret;
 435
 436         if (!kcontrol)
 437                 return -EINVAL;
 438         if (snd_BUG_ON(!card || !kcontrol->info)) {
 439                 ret = -EINVAL;
 440                 goto error;
 441         }
 442         id = kcontrol->id;
 443         down_write(&card->controls_rwsem);
 444         old = snd_ctl_find_id(card, &id);
 445         if (!old) {
 446                 if (add_on_replace)
 447                         goto add;
 448                 up_write(&card->controls_rwsem);
 449                 ret = -EINVAL;
 450                 goto error;
 451         }
 452         ret = snd_ctl_remove(card, old);
 453         if (ret < 0) {
 454                 up_write(&card->controls_rwsem);
 455                 goto error;
 456         }
 457 add:
 458         if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
 459                 up_write(&card->controls_rwsem);
 460                 ret = -ENOMEM;
 461                 goto error;
 462         }
 463         list_add_tail(&kcontrol->list, &card->controls);
 464         card->controls_count += kcontrol->count;
 465         kcontrol->id.numid = card->last_numid + 1;
 466         card->last_numid += kcontrol->count;
 467         id = kcontrol->id;
 468         count = kcontrol->count;
 469         up_write(&card->controls_rwsem);
 470         for (idx = 0; idx < count; idx++, id.index++, id.numid++)
 471                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
 472         return 0;
 473
 474 error:
 475         snd_ctl_free_one(kcontrol);
 476         return ret;
 477 }
 478 EXPORT_SYMBOL(snd_ctl_replace);
 479
 480 /**
 481  * snd_ctl_remove - remove the control from the card and release it
 482  * @card: the card instance
 483  * @kcontrol: the control instance to remove
 484  *
 485  * Removes the control from the card and then releases the instance.
 486  * You don't need to call snd_ctl_free_one(). You must be in
 487  * the write lock - down_write(&card->controls_rwsem).
 488  *
 489  * Return: 0 if successful, or a negative error code on failure.
 490  */
 491 int snd_ctl_remove(struct snd_card *card, struct snd_kcontrol *kcontrol)
 492 {
 493         struct snd_ctl_elem_id id;
 494         unsigned int idx;
 495
 496         if (snd_BUG_ON(!card || !kcontrol))
 497                 return -EINVAL;
 498         list_del(&kcontrol->list);
 499         card->controls_count -= kcontrol->count;
 500         id = kcontrol->id;
 501         for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
 502                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_REMOVE, &id);
 503         snd_ctl_free_one(kcontrol);
 504         return 0;
 505 }
 506 EXPORT_SYMBOL(snd_ctl_remove);
 507
 508 /**
 509  * snd_ctl_remove_id - remove the control of the given id and release it
 510  * @card: the card instance
 511  * @id: the control id to remove
 512  *
 513  * Finds the control instance with the given id, removes it from the
 514  * card list and releases it.
 515  *
 516  * Return: 0 if successful, or a negative error code on failure.
 517  */
 518 int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
 519 {
 520         struct snd_kcontrol *kctl;
 521         int ret;
 522
 523         down_write(&card->controls_rwsem);
 524         kctl = snd_ctl_find_id(card, id);
 525         if (kctl == NULL) {
 526                 up_write(&card->controls_rwsem);
 527                 return -ENOENT;
 528         }
 529         ret = snd_ctl_remove(card, kctl);
 530         up_write(&card->controls_rwsem);
 531         return ret;
 532 }
 533 EXPORT_SYMBOL(snd_ctl_remove_id);
 534
 535 /**
 536  * snd_ctl_remove_user_ctl - remove and release the unlocked user control
 537  * @file: active control handle
 538  * @id: the control id to remove
 539  *
 540  * Finds the control instance with the given id, removes it from the
 541  * card list and releases it.
 542  *
 543  * Return: 0 if successful, or a negative error code on failure.
 544  */
 545 static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
 546                                    struct snd_ctl_elem_id *id)
 547 {
 548         struct snd_card *card = file->card;
 549         struct snd_kcontrol *kctl;
 550         int idx, ret;
 551
 552         down_write(&card->controls_rwsem);
 553         kctl = snd_ctl_find_id(card, id);
 554         if (kctl == NULL) {
 555                 ret = -ENOENT;
 556                 goto error;
 557         }
 558         if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER)) {
 559                 ret = -EINVAL;
 560                 goto error;
 561         }
 562         for (idx = 0; idx < kctl->count; idx++)
 563                 if (kctl->vd[idx].owner != NULL && kctl->vd[idx].owner != file) {
 564                         ret = -EBUSY;
 565                         goto error;
 566                 }
 567         ret = snd_ctl_remove(card, kctl);
 568         if (ret < 0)
 569                 goto error;
 570         card->user_ctl_count--;
 571 error:
 572         up_write(&card->controls_rwsem);
 573         return ret;
 574 }
 575
 576 /**
 577  * snd_ctl_activate_id - activate/inactivate the control of the given id
 578  * @card: the card instance
 579  * @id: the control id to activate/inactivate
 580  * @active: non-zero to activate
 581  *
 582  * Finds the control instance with the given id, and activate or
 583  * inactivate the control together with notification, if changed.
 584  * The given ID data is filled with full information.
 585  *
 586  * Return: 0 if unchanged, 1 if changed, or a negative error code on failure.
 587  */
 588 int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
 589                         int active)
 590 {
 591         struct snd_kcontrol *kctl;
 592         struct snd_kcontrol_volatile *vd;
 593         unsigned int index_offset;
 594         int ret;
 595
 596         down_write(&card->controls_rwsem);
 597         kctl = snd_ctl_find_id(card, id);
 598         if (kctl == NULL) {
 599                 ret = -ENOENT;
 600                 goto unlock;
 601         }
 602         index_offset = snd_ctl_get_ioff(kctl, id);
 603         vd = &kctl->vd[index_offset];
 604         ret = 0;
 605         if (active) {
 606                 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
 607                         goto unlock;
 608                 vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
 609         } else {
 610                 if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
 611                         goto unlock;
 612                 vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
 613         }
 614         snd_ctl_build_ioff(id, kctl, index_offset);
 615         ret = 1;
 616  unlock:
 617         up_write(&card->controls_rwsem);
 618         if (ret > 0)
 619                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, id);
 620         return ret;
 621 }
 622 EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
 623
 624 /**
 625  * snd_ctl_rename_id - replace the id of a control on the card
 626  * @card: the card instance
 627  * @src_id: the old id
 628  * @dst_id: the new id
 629  *
 630  * Finds the control with the old id from the card, and replaces the
 631  * id with the new one.
 632  *
 633  * Return: Zero if successful, or a negative error code on failure.
 634  */
 635 int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
 636                       struct snd_ctl_elem_id *dst_id)
 637 {
 638         struct snd_kcontrol *kctl;
 639
 640         down_write(&card->controls_rwsem);
 641         kctl = snd_ctl_find_id(card, src_id);
 642         if (kctl == NULL) {
 643                 up_write(&card->controls_rwsem);
 644                 return -ENOENT;
 645         }
 646         kctl->id = *dst_id;
 647         kctl->id.numid = card->last_numid + 1;
 648         card->last_numid += kctl->count;
 649         up_write(&card->controls_rwsem);
 650         return 0;
 651 }
 652 EXPORT_SYMBOL(snd_ctl_rename_id);
 653
 654 /**
 655  * snd_ctl_find_numid - find the control instance with the given number-id
 656  * @card: the card instance
 657  * @numid: the number-id to search
 658  *
 659  * Finds the control instance with the given number-id from the card.
 660  *
 661  * The caller must down card->controls_rwsem before calling this function
 662  * (if the race condition can happen).
 663  *
 664  * Return: The pointer of the instance if found, or %NULL if not.
 665  *
 666  */
 667 struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card, unsigned int numid)
 668 {
 669         struct snd_kcontrol *kctl;
 670
 671         if (snd_BUG_ON(!card || !numid))
 672                 return NULL;
 673         list_for_each_entry(kctl, &card->controls, list) {
 674                 if (kctl->id.numid <= numid && kctl->id.numid + kctl->count > numid)
 675                         return kctl;
 676         }
 677         return NULL;
 678 }
 679 EXPORT_SYMBOL(snd_ctl_find_numid);
 680
 681 /**
 682  * snd_ctl_find_id - find the control instance with the given id
 683  * @card: the card instance
 684  * @id: the id to search
 685  *
 686  * Finds the control instance with the given id from the card.
 687  *
 688  * The caller must down card->controls_rwsem before calling this function
 689  * (if the race condition can happen).
 690  *
 691  * Return: The pointer of the instance if found, or %NULL if not.
 692  *
 693  */
 694 struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
 695                                      struct snd_ctl_elem_id *id)
 696 {
 697         struct snd_kcontrol *kctl;
 698
 699         if (snd_BUG_ON(!card || !id))
 700                 return NULL;
 701         if (id->numid != 0)
 702                 return snd_ctl_find_numid(card, id->numid);
 703         list_for_each_entry(kctl, &card->controls, list) {
 704                 if (kctl->id.iface != id->iface)
 705                         continue;
 706                 if (kctl->id.device != id->device)
 707                         continue;
 708                 if (kctl->id.subdevice != id->subdevice)
 709                         continue;
 710                 if (strncmp(kctl->id.name, id->name, sizeof(kctl->id.name)))
 711                         continue;
 712                 if (kctl->id.index > id->index)
 713                         continue;
 714                 if (kctl->id.index + kctl->count <= id->index)
 715                         continue;
 716                 return kctl;
 717         }
 718         return NULL;
 719 }
 720 EXPORT_SYMBOL(snd_ctl_find_id);
 721
 722 static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,
 723                              unsigned int cmd, void __user *arg)
 724 {
 725         struct snd_ctl_card_info *info;
 726
 727         info = kzalloc(sizeof(*info), GFP_KERNEL);
 728         if (! info)
 729                 return -ENOMEM;
 730         down_read(&snd_ioctl_rwsem);
 731         info->card = card->number;
 732         strlcpy(info->id, card->id, sizeof(info->id));
 733         strlcpy(info->driver, card->driver, sizeof(info->driver));
 734         strlcpy(info->name, card->shortname, sizeof(info->name));
 735         strlcpy(info->longname, card->longname, sizeof(info->longname));
 736         strlcpy(info->mixername, card->mixername, sizeof(info->mixername));
 737         strlcpy(info->components, card->components, sizeof(info->components));
 738         up_read(&snd_ioctl_rwsem);
 739         if (copy_to_user(arg, info, sizeof(struct snd_ctl_card_info))) {
 740                 kfree(info);
 741                 return -EFAULT;
 742         }
 743         kfree(info);
 744         return 0;
 745 }
 746
 747 static int snd_ctl_elem_list(struct snd_card *card,
 748                              struct snd_ctl_elem_list __user *_list)
 749 {
 750         struct snd_ctl_elem_list list;
 751         struct snd_kcontrol *kctl;
 752         struct snd_ctl_elem_id id;
 753         unsigned int offset, space, jidx;
 754         int err = 0;
 755
 756         if (copy_from_user(&list, _list, sizeof(list)))
 757                 return -EFAULT;
 758         offset = list.offset;
 759         space = list.space;
 760         /* try limit maximum space */
 761         if (space > 16384)
 762                 return -ENOMEM;
 763         down_read(&card->controls_rwsem);
 764         list.count = card->controls_count;
 765         list.used = 0;
 766         if (space > 0) {
 767                 list_for_each_entry(kctl, &card->controls, list) {
 768                         if (offset >= kctl->count) {
 769                                 offset -= kctl->count;
 770                                 continue;
 771                         }
 772                         for (jidx = offset; jidx < kctl->count; jidx++) {
 773                                 snd_ctl_build_ioff(&id, kctl, jidx);
 774                                 if (copy_to_user(list.pids + list.used, &id,
 775                                                  sizeof(id))) {
 776                                         err = -EFAULT;
 777                                         goto out;
 778                                 }
 779                                 list.used++;
 780                                 if (!--space)
 781                                         goto out;
 782                         }
 783                         offset = 0;
 784                 }
 785         }
 786  out:
 787         up_read(&card->controls_rwsem);
 788         if (!err && copy_to_user(_list, &list, sizeof(list)))
 789                 err = -EFAULT;
 790         return err;
 791 }
 792
 793 static bool validate_element_member_dimension(struct snd_ctl_elem_info *info)
 794 {
 795         unsigned int members;
 796         unsigned int i;
 797
 798         if (info->dimen.d[0] == 0)
 799                 return true;
 800
 801         members = 1;
 802         for (i = 0; i < ARRAY_SIZE(info->dimen.d); ++i) {
 803                 if (info->dimen.d[i] == 0)
 804                         break;
 805                 members *= info->dimen.d[i];
 806
 807                 /*
 808                  * info->count should be validated in advance, to guarantee
 809                  * calculation soundness.
 810                  */
 811                 if (members > info->count)
 812                         return false;
 813         }
 814
 815         for (++i; i < ARRAY_SIZE(info->dimen.d); ++i) {
 816                 if (info->dimen.d[i] > 0)
 817                         return false;
 818         }
 819
 820         return members == info->count;
 821 }
 822
 823 static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
 824                              struct snd_ctl_elem_info *info)
 825 {
 826         struct snd_card *card = ctl->card;
 827         struct snd_kcontrol *kctl;
 828         struct snd_kcontrol_volatile *vd;
 829         unsigned int index_offset;
 830         int result;
 831
 832         down_read(&card->controls_rwsem);
 833         kctl = snd_ctl_find_id(card, &info->id);
 834         if (kctl == NULL) {
 835                 up_read(&card->controls_rwsem);
 836                 return -ENOENT;
 837         }
 838 #ifdef CONFIG_SND_DEBUG
 839         info->access = 0;
 840 #endif
 841         result = kctl->info(kctl, info);
 842         if (result >= 0) {
 843                 snd_BUG_ON(info->access);
 844                 index_offset = snd_ctl_get_ioff(kctl, &info->id);
 845                 vd = &kctl->vd[index_offset];
 846                 snd_ctl_build_ioff(&info->id, kctl, index_offset);
 847                 info->access = vd->access;
 848                 if (vd->owner) {
 849                         info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
 850                         if (vd->owner == ctl)
 851                                 info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
 852                         info->owner = pid_vnr(vd->owner->pid);
 853                 } else {
 854                         info->owner = -1;
 855                 }
 856         }
 857         up_read(&card->controls_rwsem);
 858         return result;
 859 }
 860
 861 static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
 862                                   struct snd_ctl_elem_info __user *_info)
 863 {
 864         struct snd_ctl_elem_info info;
 865         int result;
 866
 867         if (copy_from_user(&info, _info, sizeof(info)))
 868                 return -EFAULT;
 869         snd_power_lock(ctl->card);
 870         result = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);
 871         if (result >= 0)
 872                 result = snd_ctl_elem_info(ctl, &info);
 873         snd_power_unlock(ctl->card);
 874         if (result >= 0)
 875                 if (copy_to_user(_info, &info, sizeof(info)))
 876                         return -EFAULT;
 877         return result;
 878 }
 879
 880 static int snd_ctl_elem_read(struct snd_card *card,
 881                              struct snd_ctl_elem_value *control)
 882 {
 883         struct snd_kcontrol *kctl;
 884         struct snd_kcontrol_volatile *vd;
 885         unsigned int index_offset;
 886         int result;
 887
 888         down_read(&card->controls_rwsem);
 889         kctl = snd_ctl_find_id(card, &control->id);
 890         if (kctl == NULL) {
 891                 result = -ENOENT;
 892         } else {
 893                 index_offset = snd_ctl_get_ioff(kctl, &control->id);
 894                 vd = &kctl->vd[index_offset];
 895                 if ((vd->access & SNDRV_CTL_ELEM_ACCESS_READ) &&
 896                     kctl->get != NULL) {
 897                         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 898                         result = kctl->get(kctl, control);
 899                 } else
 900                         result = -EPERM;
 901         }
 902         up_read(&card->controls_rwsem);
 903         return result;
 904 }
 905
 906 static int snd_ctl_elem_read_user(struct snd_card *card,
 907                                   struct snd_ctl_elem_value __user *_control)
 908 {
 909         struct snd_ctl_elem_value *control;
 910         int result;
 911
 912         control = memdup_user(_control, sizeof(*control));
 913         if (IS_ERR(control))
 914                 return PTR_ERR(control);
 915
 916         snd_power_lock(card);
 917         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 918         if (result >= 0)
 919                 result = snd_ctl_elem_read(card, control);
 920         snd_power_unlock(card);
 921         if (result >= 0)
 922                 if (copy_to_user(_control, control, sizeof(*control)))
 923                         result = -EFAULT;
 924         kfree(control);
 925         return result;
 926 }
 927
 928 static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
 929                               struct snd_ctl_elem_value *control)
 930 {
 931         struct snd_kcontrol *kctl;
 932         struct snd_kcontrol_volatile *vd;
 933         unsigned int index_offset;
 934         int result;
 935
 936         down_read(&card->controls_rwsem);
 937         kctl = snd_ctl_find_id(card, &control->id);
 938         if (kctl == NULL) {
 939                 result = -ENOENT;
 940         } else {
 941                 index_offset = snd_ctl_get_ioff(kctl, &control->id);
 942                 vd = &kctl->vd[index_offset];
 943                 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_WRITE) ||
 944                     kctl->put == NULL ||
 945                     (file && vd->owner && vd->owner != file)) {
 946                         result = -EPERM;
 947                 } else {
 948                         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 949                         result = kctl->put(kctl, control);
 950                 }
 951                 if (result > 0) {
 952                         struct snd_ctl_elem_id id = control->id;
 953                         up_read(&card->controls_rwsem);
 954                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, &id);
 955                         return 0;
 956                 }
 957         }
 958         up_read(&card->controls_rwsem);
 959         return result;
 960 }
 961
 962 static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
 963                                    struct snd_ctl_elem_value __user *_control)
 964 {
 965         struct snd_ctl_elem_value *control;
 966         struct snd_card *card;
 967         int result;
 968
 969         control = memdup_user(_control, sizeof(*control));
 970         if (IS_ERR(control))
 971                 return PTR_ERR(control);
 972
 973         card = file->card;
 974         snd_power_lock(card);
 975         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 976         if (result >= 0)
 977                 result = snd_ctl_elem_write(card, file, control);
 978         snd_power_unlock(card);
 979         if (result >= 0)
 980                 if (copy_to_user(_control, control, sizeof(*control)))
 981                         result = -EFAULT;
 982         kfree(control);
 983         return result;
 984 }
 985
 986 static int snd_ctl_elem_lock(struct snd_ctl_file *file,
 987                              struct snd_ctl_elem_id __user *_id)
 988 {
 989         struct snd_card *card = file->card;
 990         struct snd_ctl_elem_id id;
 991         struct snd_kcontrol *kctl;
 992         struct snd_kcontrol_volatile *vd;
 993         int result;
 994
 995         if (copy_from_user(&id, _id, sizeof(id)))
 996                 return -EFAULT;
 997         down_write(&card->controls_rwsem);
 998         kctl = snd_ctl_find_id(card, &id);
 999         if (kctl == NULL) {
1000                 result = -ENOENT;
1001         } else {
1002                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1003                 if (vd->owner != NULL)
1004                         result = -EBUSY;
1005                 else {
1006                         vd->owner = file;
1007                         result = 0;
1008                 }
1009         }
1010         up_write(&card->controls_rwsem);
1011         return result;
1012 }
1013
1014 static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
1015                                struct snd_ctl_elem_id __user *_id)
1016 {
1017         struct snd_card *card = file->card;
1018         struct snd_ctl_elem_id id;
1019         struct snd_kcontrol *kctl;
1020         struct snd_kcontrol_volatile *vd;
1021         int result;
1022
1023         if (copy_from_user(&id, _id, sizeof(id)))
1024                 return -EFAULT;
1025         down_write(&card->controls_rwsem);
1026         kctl = snd_ctl_find_id(card, &id);
1027         if (kctl == NULL) {
1028                 result = -ENOENT;
1029         } else {
1030                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1031                 if (vd->owner == NULL)
1032                         result = -EINVAL;
1033                 else if (vd->owner != file)
1034                         result = -EPERM;
1035                 else {
1036                         vd->owner = NULL;
1037                         result = 0;
1038                 }
1039         }
1040         up_write(&card->controls_rwsem);
1041         return result;
1042 }
1043
1044 struct user_element {
1045         struct snd_ctl_elem_info info;
1046         struct snd_card *card;
1047         char *elem_data;                /* element data */
1048         unsigned long elem_data_size;   /* size of element data in bytes */
1049         void *tlv_data;                 /* TLV data */
1050         unsigned long tlv_data_size;    /* TLV data size */
1051         void *priv_data;                /* private data (like strings for enumerated type) */
1052 };
1053
1054 static int snd_ctl_elem_user_info(struct snd_kcontrol *kcontrol,
1055                                   struct snd_ctl_elem_info *uinfo)
1056 {
1057         struct user_element *ue = kcontrol->private_data;
1058         unsigned int offset;
1059
1060         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1061         *uinfo = ue->info;
1062         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1063
1064         return 0;
1065 }
1066
1067 static int snd_ctl_elem_user_enum_info(struct snd_kcontrol *kcontrol,
1068                                        struct snd_ctl_elem_info *uinfo)
1069 {
1070         struct user_element *ue = kcontrol->private_data;
1071         const char *names;
1072         unsigned int item;
1073         unsigned int offset;
1074
1075         item = uinfo->value.enumerated.item;
1076
1077         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1078         *uinfo = ue->info;
1079         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1080
1081         item = min(item, uinfo->value.enumerated.items - 1);
1082         uinfo->value.enumerated.item = item;
1083
1084         names = ue->priv_data;
1085         for (; item > 0; --item)
1086                 names += strlen(names) + 1;
1087         strcpy(uinfo->value.enumerated.name, names);
1088
1089         return 0;
1090 }
1091
1092 static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
1093                                  struct snd_ctl_elem_value *ucontrol)
1094 {
1095         struct user_element *ue = kcontrol->private_data;
1096         unsigned int size = ue->elem_data_size;
1097         char *src = ue->elem_data +
1098                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1099
1100         mutex_lock(&ue->card->user_ctl_lock);
1101         memcpy(&ucontrol->value, src, size);
1102         mutex_unlock(&ue->card->user_ctl_lock);
1103         return 0;
1104 }
1105
1106 static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
1107                                  struct snd_ctl_elem_value *ucontrol)
1108 {
1109         int change;
1110         struct user_element *ue = kcontrol->private_data;
1111         unsigned int size = ue->elem_data_size;
1112         char *dst = ue->elem_data +
1113                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1114
1115         mutex_lock(&ue->card->user_ctl_lock);
1116         change = memcmp(&ucontrol->value, dst, size) != 0;
1117         if (change)
1118                 memcpy(dst, &ucontrol->value, size);
1119         mutex_unlock(&ue->card->user_ctl_lock);
1120         return change;
1121 }
1122
1123 static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol,
1124                                  int op_flag,
1125                                  unsigned int size,
1126                                  unsigned int __user *tlv)
1127 {
1128         struct user_element *ue = kcontrol->private_data;
1129         int change = 0;
1130         void *new_data;
1131
1132         if (op_flag == SNDRV_CTL_TLV_OP_WRITE) {
1133                 if (size > 1024 * 128)  /* sane value */
1134                         return -EINVAL;
1135
1136                 new_data = memdup_user(tlv, size);
1137                 if (IS_ERR(new_data))
1138                         return PTR_ERR(new_data);
1139                 mutex_lock(&ue->card->user_ctl_lock);
1140                 change = ue->tlv_data_size != size;
1141                 if (!change)
1142                         change = memcmp(ue->tlv_data, new_data, size);
1143                 kfree(ue->tlv_data);
1144                 ue->tlv_data = new_data;
1145                 ue->tlv_data_size = size;
1146                 mutex_unlock(&ue->card->user_ctl_lock);
1147         } else {
1148                 int ret = 0;
1149
1150                 mutex_lock(&ue->card->user_ctl_lock);
1151                 if (!ue->tlv_data_size || !ue->tlv_data) {
1152                         ret = -ENXIO;
1153                         goto err_unlock;
1154                 }
1155                 if (size < ue->tlv_data_size) {
1156                         ret = -ENOSPC;
1157                         goto err_unlock;
1158                 }
1159                 if (copy_to_user(tlv, ue->tlv_data, ue->tlv_data_size))
1160                         ret = -EFAULT;
1161 err_unlock:
1162                 mutex_unlock(&ue->card->user_ctl_lock);
1163                 if (ret)
1164                         return ret;
1165         }
1166         return change;
1167 }
1168
1169 static int snd_ctl_elem_init_enum_names(struct user_element *ue)
1170 {
1171         char *names, *p;
1172         size_t buf_len, name_len;
1173         unsigned int i;
1174         const uintptr_t user_ptrval = ue->info.value.enumerated.names_ptr;
1175
1176         if (ue->info.value.enumerated.names_length > 64 * 1024)
1177                 return -EINVAL;
1178
1179         names = memdup_user((const void __user *)user_ptrval,
1180                 ue->info.value.enumerated.names_length);
1181         if (IS_ERR(names))
1182                 return PTR_ERR(names);
1183
1184         /* check that there are enough valid names */
1185         buf_len = ue->info.value.enumerated.names_length;
1186         p = names;
1187         for (i = 0; i < ue->info.value.enumerated.items; ++i) {
1188                 name_len = strnlen(p, buf_len);
1189                 if (name_len == 0 || name_len >= 64 || name_len == buf_len) {
1190                         kfree(names);
1191                         return -EINVAL;
1192                 }
1193                 p += name_len + 1;
1194                 buf_len -= name_len + 1;
1195         }
1196
1197         ue->priv_data = names;
1198         ue->info.value.enumerated.names_ptr = 0;
1199
1200         return 0;
1201 }
1202
1203 static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)
1204 {
1205         struct user_element *ue = kcontrol->private_data;
1206
1207         kfree(ue->tlv_data);
1208         kfree(ue->priv_data);
1209         kfree(ue);
1210 }
1211
1212 static int snd_ctl_elem_add(struct snd_ctl_file *file,
1213                             struct snd_ctl_elem_info *info, int replace)
1214 {
1215         /* The capacity of struct snd_ctl_elem_value.value.*/
1216         static const unsigned int value_sizes[] = {
1217                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = sizeof(long),
1218                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = sizeof(long),
1219                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = sizeof(unsigned int),
1220                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = sizeof(unsigned char),
1221                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = sizeof(struct snd_aes_iec958),
1222                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = sizeof(long long),
1223         };
1224         static const unsigned int max_value_counts[] = {
1225                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = 128,
1226                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = 128,
1227                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = 128,
1228                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = 512,
1229                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = 1,
1230                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = 64,
1231         };
1232         struct snd_card *card = file->card;
1233         struct snd_kcontrol *kctl;
1234         unsigned int count;
1235         unsigned int access;
1236         long private_size;
1237         struct user_element *ue;
1238         unsigned int offset;
1239         int err;
1240
1241         if (!*info->id.name)
1242                 return -EINVAL;
1243         if (strnlen(info->id.name, sizeof(info->id.name)) >= sizeof(info->id.name))
1244                 return -EINVAL;
1245
1246         /* Delete a control to replace them if needed. */
1247         if (replace) {
1248                 info->id.numid = 0;
1249                 err = snd_ctl_remove_user_ctl(file, &info->id);
1250                 if (err)
1251                         return err;
1252         }
1253
1254         /*
1255          * The number of userspace controls are counted control by control,
1256          * not element by element.
1257          */
1258         if (card->user_ctl_count + 1 > MAX_USER_CONTROLS)
1259                 return -ENOMEM;
1260
1261         /* Check the number of elements for this userspace control. */
1262         count = info->owner;
1263         if (count == 0)
1264                 count = 1;
1265
1266         /* Arrange access permissions if needed. */
1267         access = info->access;
1268         if (access == 0)
1269                 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
1270         access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
1271                    SNDRV_CTL_ELEM_ACCESS_INACTIVE |
1272                    SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE);
1273         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE)
1274                 access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
1275         access |= SNDRV_CTL_ELEM_ACCESS_USER;
1276
1277         /*
1278          * Check information and calculate the size of data specific to
1279          * this userspace control.
1280          */
1281         if (info->type < SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
1282             info->type > SNDRV_CTL_ELEM_TYPE_INTEGER64)
1283                 return -EINVAL;
1284         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED &&
1285             info->value.enumerated.items == 0)
1286                 return -EINVAL;
1287         if (info->count < 1 ||
1288             info->count > max_value_counts[info->type])
1289                 return -EINVAL;
1290         if (!validate_element_member_dimension(info))
1291                 return -EINVAL;
1292         private_size = value_sizes[info->type] * info->count;
1293
1294         /*
1295          * Keep memory object for this userspace control. After passing this
1296          * code block, the instance should be freed by snd_ctl_free_one().
1297          *
1298          * Note that these elements in this control are locked.
1299          */
1300         err = snd_ctl_new(&kctl, count, access, file);
1301         if (err < 0)
1302                 return err;
1303         memcpy(&kctl->id, &info->id, sizeof(kctl->id));
1304         kctl->private_data = kzalloc(sizeof(struct user_element) + private_size * count,
1305                                      GFP_KERNEL);
1306         if (kctl->private_data == NULL) {
1307                 kfree(kctl);
1308                 return -ENOMEM;
1309         }
1310         kctl->private_free = snd_ctl_elem_user_free;
1311
1312         /* Set private data for this userspace control. */
1313         ue = (struct user_element *)kctl->private_data;
1314         ue->card = card;
1315         ue->info = *info;
1316         ue->info.access = 0;
1317         ue->elem_data = (char *)ue + sizeof(*ue);
1318         ue->elem_data_size = private_size;
1319         if (ue->info.type == SNDRV_CTL_ELEM_TYPE_ENUMERATED) {
1320                 err = snd_ctl_elem_init_enum_names(ue);
1321                 if (err < 0) {
1322                         snd_ctl_free_one(kctl);
1323                         return err;
1324                 }
1325         }
1326
1327         /* Set callback functions. */
1328         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
1329                 kctl->info = snd_ctl_elem_user_enum_info;
1330         else
1331                 kctl->info = snd_ctl_elem_user_info;
1332         if (access & SNDRV_CTL_ELEM_ACCESS_READ)
1333                 kctl->get = snd_ctl_elem_user_get;
1334         if (access & SNDRV_CTL_ELEM_ACCESS_WRITE)
1335                 kctl->put = snd_ctl_elem_user_put;
1336         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE)
1337                 kctl->tlv.c = snd_ctl_elem_user_tlv;
1338
1339         /* This function manage to free the instance on failure. */
1340         err = snd_ctl_add(card, kctl);
1341         if (err < 0)
1342                 return err;
1343         offset = snd_ctl_get_ioff(kctl, &info->id);
1344         snd_ctl_build_ioff(&info->id, kctl, offset);
1345         /*
1346          * Here we cannot fill any field for the number of elements added by
1347          * this operation because there're no specific fields. The usage of
1348          * 'owner' field for this purpose may cause any bugs to userspace
1349          * applications because the field originally means PID of a process
1350          * which locks the element.
1351          */
1352
1353         down_write(&card->controls_rwsem);
1354         card->user_ctl_count++;
1355         up_write(&card->controls_rwsem);
1356
1357         return 0;
1358 }
1359
1360 static int snd_ctl_elem_add_user(struct snd_ctl_file *file,
1361                                  struct snd_ctl_elem_info __user *_info, int replace)
1362 {
1363         struct snd_ctl_elem_info info;
1364         int err;
1365
1366         if (copy_from_user(&info, _info, sizeof(info)))
1367                 return -EFAULT;
1368         err = snd_ctl_elem_add(file, &info, replace);
1369         if (err < 0)
1370                 return err;
1371         if (copy_to_user(_info, &info, sizeof(info))) {
1372                 snd_ctl_remove_user_ctl(file, &info.id);
1373                 return -EFAULT;
1374         }
1375
1376         return 0;
1377 }
1378
1379 static int snd_ctl_elem_remove(struct snd_ctl_file *file,
1380                                struct snd_ctl_elem_id __user *_id)
1381 {
1382         struct snd_ctl_elem_id id;
1383
1384         if (copy_from_user(&id, _id, sizeof(id)))
1385                 return -EFAULT;
1386         return snd_ctl_remove_user_ctl(file, &id);
1387 }
1388
1389 static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
1390 {
1391         int subscribe;
1392         if (get_user(subscribe, ptr))
1393                 return -EFAULT;
1394         if (subscribe < 0) {
1395                 subscribe = file->subscribed;
1396                 if (put_user(subscribe, ptr))
1397                         return -EFAULT;
1398                 return 0;
1399         }
1400         if (subscribe) {
1401                 file->subscribed = 1;
1402                 return 0;
1403         } else if (file->subscribed) {
1404                 snd_ctl_empty_read_queue(file);
1405                 file->subscribed = 0;
1406         }
1407         return 0;
1408 }
1409
1410 static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
1411                              struct snd_ctl_tlv __user *_tlv,
1412                              int op_flag)
1413 {
1414         struct snd_card *card = file->card;
1415         struct snd_ctl_tlv tlv;
1416         struct snd_kcontrol *kctl;
1417         struct snd_kcontrol_volatile *vd;
1418         unsigned int len;
1419         int err = 0;
1420
1421         if (copy_from_user(&tlv, _tlv, sizeof(tlv)))
1422                 return -EFAULT;
1423         if (tlv.length < sizeof(unsigned int) * 2)
1424                 return -EINVAL;
1425         if (!tlv.numid)
1426                 return -EINVAL;
1427         down_read(&card->controls_rwsem);
1428         kctl = snd_ctl_find_numid(card, tlv.numid);
1429         if (kctl == NULL) {
1430                 err = -ENOENT;
1431                 goto __kctl_end;
1432         }
1433         if (kctl->tlv.p == NULL) {
1434                 err = -ENXIO;
1435                 goto __kctl_end;
1436         }
1437         vd = &kctl->vd[tlv.numid - kctl->id.numid];
1438         if ((op_flag == SNDRV_CTL_TLV_OP_READ &&
1439              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ) == 0) ||
1440             (op_flag == SNDRV_CTL_TLV_OP_WRITE &&
1441              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE) == 0) ||
1442             (op_flag == SNDRV_CTL_TLV_OP_CMD &&
1443              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND) == 0)) {
1444                 err = -ENXIO;
1445                 goto __kctl_end;
1446         }
1447         if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
1448                 if (vd->owner != NULL && vd->owner != file) {
1449                         err = -EPERM;
1450                         goto __kctl_end;
1451                 }
1452                 err = kctl->tlv.c(kctl, op_flag, tlv.length, _tlv->tlv);
1453                 if (err > 0) {
1454                         struct snd_ctl_elem_id id = kctl->id;
1455                         up_read(&card->controls_rwsem);
1456                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_TLV, &id);
1457                         return 0;
1458                 }
1459         } else {
1460                 if (op_flag != SNDRV_CTL_TLV_OP_READ) {
1461                         err = -ENXIO;
1462                         goto __kctl_end;
1463                 }
1464                 len = kctl->tlv.p[1] + 2 * sizeof(unsigned int);
1465                 if (tlv.length < len) {
1466                         err = -ENOMEM;
1467                         goto __kctl_end;
1468                 }
1469                 if (copy_to_user(_tlv->tlv, kctl->tlv.p, len))
1470                         err = -EFAULT;
1471         }
1472       __kctl_end:
1473         up_read(&card->controls_rwsem);
1474         return err;
1475 }
1476
1477 static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1478 {
1479         struct snd_ctl_file *ctl;
1480         struct snd_card *card;
1481         struct snd_kctl_ioctl *p;
1482         void __user *argp = (void __user *)arg;
1483         int __user *ip = argp;
1484         int err;
1485
1486         ctl = file->private_data;
1487         card = ctl->card;
1488         if (snd_BUG_ON(!card))
1489                 return -ENXIO;
1490         switch (cmd) {
1491         case SNDRV_CTL_IOCTL_PVERSION:
1492                 return put_user(SNDRV_CTL_VERSION, ip) ? -EFAULT : 0;
1493         case SNDRV_CTL_IOCTL_CARD_INFO:
1494                 return snd_ctl_card_info(card, ctl, cmd, argp);
1495         case SNDRV_CTL_IOCTL_ELEM_LIST:
1496                 return snd_ctl_elem_list(card, argp);
1497         case SNDRV_CTL_IOCTL_ELEM_INFO:
1498                 return snd_ctl_elem_info_user(ctl, argp);
1499         case SNDRV_CTL_IOCTL_ELEM_READ:
1500                 return snd_ctl_elem_read_user(card, argp);
1501         case SNDRV_CTL_IOCTL_ELEM_WRITE:
1502                 return snd_ctl_elem_write_user(ctl, argp);
1503         case SNDRV_CTL_IOCTL_ELEM_LOCK:
1504                 return snd_ctl_elem_lock(ctl, argp);
1505         case SNDRV_CTL_IOCTL_ELEM_UNLOCK:
1506                 return snd_ctl_elem_unlock(ctl, argp);
1507         case SNDRV_CTL_IOCTL_ELEM_ADD:
1508                 return snd_ctl_elem_add_user(ctl, argp, 0);
1509         case SNDRV_CTL_IOCTL_ELEM_REPLACE:
1510                 return snd_ctl_elem_add_user(ctl, argp, 1);
1511         case SNDRV_CTL_IOCTL_ELEM_REMOVE:
1512                 return snd_ctl_elem_remove(ctl, argp);
1513         case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
1514                 return snd_ctl_subscribe_events(ctl, ip);
1515         case SNDRV_CTL_IOCTL_TLV_READ:
1516                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_READ);
1517         case SNDRV_CTL_IOCTL_TLV_WRITE:
1518                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_WRITE);
1519         case SNDRV_CTL_IOCTL_TLV_COMMAND:
1520                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_CMD);
1521         case SNDRV_CTL_IOCTL_POWER:
1522                 return -ENOPROTOOPT;
1523         case SNDRV_CTL_IOCTL_POWER_STATE:
1524 #ifdef CONFIG_PM
1525                 return put_user(card->power_state, ip) ? -EFAULT : 0;
1526 #else
1527                 return put_user(SNDRV_CTL_POWER_D0, ip) ? -EFAULT : 0;
1528 #endif
1529         }
1530         down_read(&snd_ioctl_rwsem);
1531         list_for_each_entry(p, &snd_control_ioctls, list) {
1532                 err = p->fioctl(card, ctl, cmd, arg);
1533                 if (err != -ENOIOCTLCMD) {
1534                         up_read(&snd_ioctl_rwsem);
1535                         return err;
1536                 }
1537         }
1538         up_read(&snd_ioctl_rwsem);
1539         dev_dbg(card->dev, "unknown ioctl = 0x%x\n", cmd);
1540         return -ENOTTY;
1541 }
1542
1543 static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
1544                             size_t count, loff_t * offset)
1545 {
1546         struct snd_ctl_file *ctl;
1547         int err = 0;
1548         ssize_t result = 0;
1549
1550         ctl = file->private_data;
1551         if (snd_BUG_ON(!ctl || !ctl->card))
1552                 return -ENXIO;
1553         if (!ctl->subscribed)
1554                 return -EBADFD;
1555         if (count < sizeof(struct snd_ctl_event))
1556                 return -EINVAL;
1557         spin_lock_irq(&ctl->read_lock);
1558         while (count >= sizeof(struct snd_ctl_event)) {
1559                 struct snd_ctl_event ev;
1560                 struct snd_kctl_event *kev;
1561                 while (list_empty(&ctl->events)) {
1562                         wait_queue_t wait;
1563                         if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
1564                                 err = -EAGAIN;
1565                                 goto __end_lock;
1566                         }
1567                         init_waitqueue_entry(&wait, current);
1568                         add_wait_queue(&ctl->change_sleep, &wait);
1569                         set_current_state(TASK_INTERRUPTIBLE);
1570                         spin_unlock_irq(&ctl->read_lock);
1571                         schedule();
1572                         remove_wait_queue(&ctl->change_sleep, &wait);
1573                         if (ctl->card->shutdown)
1574                                 return -ENODEV;
1575                         if (signal_pending(current))
1576                                 return -ERESTARTSYS;
1577                         spin_lock_irq(&ctl->read_lock);
1578                 }
1579                 kev = snd_kctl_event(ctl->events.next);
1580                 ev.type = SNDRV_CTL_EVENT_ELEM;
1581                 ev.data.elem.mask = kev->mask;
1582                 ev.data.elem.id = kev->id;
1583                 list_del(&kev->list);
1584                 spin_unlock_irq(&ctl->read_lock);
1585                 kfree(kev);
1586                 if (copy_to_user(buffer, &ev, sizeof(struct snd_ctl_event))) {
1587                         err = -EFAULT;
1588                         goto __end;
1589                 }
1590                 spin_lock_irq(&ctl->read_lock);
1591                 buffer += sizeof(struct snd_ctl_event);
1592                 count -= sizeof(struct snd_ctl_event);
1593                 result += sizeof(struct snd_ctl_event);
1594         }
1595       __end_lock:
1596         spin_unlock_irq(&ctl->read_lock);
1597       __end:
1598         return result > 0 ? result : err;
1599 }
1600
1601 static unsigned int snd_ctl_poll(struct file *file, poll_table * wait)
1602 {
1603         unsigned int mask;
1604         struct snd_ctl_file *ctl;
1605
1606         ctl = file->private_data;
1607         if (!ctl->subscribed)
1608                 return 0;
1609         poll_wait(file, &ctl->change_sleep, wait);
1610
1611         mask = 0;
1612         if (!list_empty(&ctl->events))
1613                 mask |= POLLIN | POLLRDNORM;
1614
1615         return mask;
1616 }
1617
1618 /*
1619  * register the device-specific control-ioctls.
1620  * called from each device manager like pcm.c, hwdep.c, etc.
1621  */
1622 static int _snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn, struct list_head *lists)
1623 {
1624         struct snd_kctl_ioctl *pn;
1625
1626         pn = kzalloc(sizeof(struct snd_kctl_ioctl), GFP_KERNEL);
1627         if (pn == NULL)
1628                 return -ENOMEM;
1629         pn->fioctl = fcn;
1630         down_write(&snd_ioctl_rwsem);
1631         list_add_tail(&pn->list, lists);
1632         up_write(&snd_ioctl_rwsem);
1633         return 0;
1634 }
1635
1636 /**
1637  * snd_ctl_register_ioctl - register the device-specific control-ioctls
1638  * @fcn: ioctl callback function
1639  *
1640  * called from each device manager like pcm.c, hwdep.c, etc.
1641  */
1642 int snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn)
1643 {
1644         return _snd_ctl_register_ioctl(fcn, &snd_control_ioctls);
1645 }
1646 EXPORT_SYMBOL(snd_ctl_register_ioctl);
1647
1648 #ifdef CONFIG_COMPAT
1649 /**
1650  * snd_ctl_register_ioctl_compat - register the device-specific 32bit compat
1651  * control-ioctls
1652  * @fcn: ioctl callback function
1653  */
1654 int snd_ctl_register_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1655 {
1656         return _snd_ctl_register_ioctl(fcn, &snd_control_compat_ioctls);
1657 }
1658 EXPORT_SYMBOL(snd_ctl_register_ioctl_compat);
1659 #endif
1660
1661 /*
1662  * de-register the device-specific control-ioctls.
1663  */
1664 static int _snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn,
1665                                      struct list_head *lists)
1666 {
1667         struct snd_kctl_ioctl *p;
1668
1669         if (snd_BUG_ON(!fcn))
1670                 return -EINVAL;
1671         down_write(&snd_ioctl_rwsem);
1672         list_for_each_entry(p, lists, list) {
1673                 if (p->fioctl == fcn) {
1674                         list_del(&p->list);
1675                         up_write(&snd_ioctl_rwsem);
1676                         kfree(p);
1677                         return 0;
1678                 }
1679         }
1680         up_write(&snd_ioctl_rwsem);
1681         snd_BUG();
1682         return -EINVAL;
1683 }
1684
1685 /**
1686  * snd_ctl_unregister_ioctl - de-register the device-specific control-ioctls
1687  * @fcn: ioctl callback function to unregister
1688  */
1689 int snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn)
1690 {
1691         return _snd_ctl_unregister_ioctl(fcn, &snd_control_ioctls);
1692 }
1693 EXPORT_SYMBOL(snd_ctl_unregister_ioctl);
1694
1695 #ifdef CONFIG_COMPAT
1696 /**
1697  * snd_ctl_unregister_ioctl - de-register the device-specific compat 32bit
1698  * control-ioctls
1699  * @fcn: ioctl callback function to unregister
1700  */
1701 int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1702 {
1703         return _snd_ctl_unregister_ioctl(fcn, &snd_control_compat_ioctls);
1704 }
1705 EXPORT_SYMBOL(snd_ctl_unregister_ioctl_compat);
1706 #endif
1707
1708 static int snd_ctl_fasync(int fd, struct file * file, int on)
1709 {
1710         struct snd_ctl_file *ctl;
1711
1712         ctl = file->private_data;
1713         return fasync_helper(fd, file, on, &ctl->fasync);
1714 }
1715
1716 /* return the preferred subdevice number if already assigned;
1717  * otherwise return -1
1718  */
1719 int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type)
1720 {
1721         struct snd_ctl_file *kctl;
1722         int subdevice = -1;
1723
1724         read_lock(&card->ctl_files_rwlock);
1725         list_for_each_entry(kctl, &card->ctl_files, list) {
1726                 if (kctl->pid == task_pid(current)) {
1727                         subdevice = kctl->preferred_subdevice[type];
1728                         if (subdevice != -1)
1729                                 break;
1730                 }
1731         }
1732         read_unlock(&card->ctl_files_rwlock);
1733         return subdevice;
1734 }
1735 EXPORT_SYMBOL_GPL(snd_ctl_get_preferred_subdevice);
1736
1737 /*
1738  * ioctl32 compat
1739  */
1740 #ifdef CONFIG_COMPAT
1741 #include "control_compat.c"
1742 #else
1743 #define snd_ctl_ioctl_compat    NULL
1744 #endif
1745
1746 /*
1747  *  INIT PART
1748  */
1749
1750 static const struct file_operations snd_ctl_f_ops =
1751 {
1752         .owner =        THIS_MODULE,
1753         .read =         snd_ctl_read,
1754         .open =         snd_ctl_open,
1755         .release =      snd_ctl_release,
1756         .llseek =       no_llseek,
1757         .poll =         snd_ctl_poll,
1758         .unlocked_ioctl =       snd_ctl_ioctl,
1759         .compat_ioctl = snd_ctl_ioctl_compat,
1760         .fasync =       snd_ctl_fasync,
1761 };
1762
1763 /*
1764  * registration of the control device
1765  */
1766 static int snd_ctl_dev_register(struct snd_device *device)
1767 {
1768         struct snd_card *card = device->device_data;
1769
1770         return snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
1771                                    &snd_ctl_f_ops, card, &card->ctl_dev);
1772 }
1773
1774 /*
1775  * disconnection of the control device
1776  */
1777 static int snd_ctl_dev_disconnect(struct snd_device *device)
1778 {
1779         struct snd_card *card = device->device_data;
1780         struct snd_ctl_file *ctl;
1781
1782         read_lock(&card->ctl_files_rwlock);
1783         list_for_each_entry(ctl, &card->ctl_files, list) {
1784                 wake_up(&ctl->change_sleep);
1785                 kill_fasync(&ctl->fasync, SIGIO, POLL_ERR);
1786         }
1787         read_unlock(&card->ctl_files_rwlock);
1788
1789         return snd_unregister_device(&card->ctl_dev);
1790 }
1791
1792 /*
1793  * free all controls
1794  */
1795 static int snd_ctl_dev_free(struct snd_device *device)
1796 {
1797         struct snd_card *card = device->device_data;
1798         struct snd_kcontrol *control;
1799
1800         down_write(&card->controls_rwsem);
1801         while (!list_empty(&card->controls)) {
1802                 control = snd_kcontrol(card->controls.next);
1803                 snd_ctl_remove(card, control);
1804         }
1805         up_write(&card->controls_rwsem);
1806         put_device(&card->ctl_dev);
1807         return 0;
1808 }
1809
1810 /*
1811  * create control core:
1812  * called from init.c
1813  */
1814 int snd_ctl_create(struct snd_card *card)
1815 {
1816         static struct snd_device_ops ops = {
1817                 .dev_free = snd_ctl_dev_free,
1818                 .dev_register = snd_ctl_dev_register,
1819                 .dev_disconnect = snd_ctl_dev_disconnect,
1820         };
1821         int err;
1822
1823         if (snd_BUG_ON(!card))
1824                 return -ENXIO;
1825         if (snd_BUG_ON(card->number < 0 || card->number >= SNDRV_CARDS))
1826                 return -ENXIO;
1827
1828         snd_device_initialize(&card->ctl_dev, card);
1829         dev_set_name(&card->ctl_dev, "controlC%d", card->number);
1830
1831         err = snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
1832         if (err < 0)
1833                 put_device(&card->ctl_dev);
1834         return err;
1835 }
1836
1837 /*
1838  * Frequently used control callbacks/helpers
1839  */
1840
1841 /**
1842  * snd_ctl_boolean_mono_info - Helper function for a standard boolean info
1843  * callback with a mono channel
1844  * @kcontrol: the kcontrol instance
1845  * @uinfo: info to store
1846  *
1847  * This is a function that can be used as info callback for a standard
1848  * boolean control with a single mono channel.
1849  */
1850 int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
1851                               struct snd_ctl_elem_info *uinfo)
1852 {
1853         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1854         uinfo->count = 1;
1855         uinfo->value.integer.min = 0;
1856         uinfo->value.integer.max = 1;
1857         return 0;
1858 }
1859 EXPORT_SYMBOL(snd_ctl_boolean_mono_info);
1860
1861 /**
1862  * snd_ctl_boolean_stereo_info - Helper function for a standard boolean info
1863  * callback with stereo two channels
1864  * @kcontrol: the kcontrol instance
1865  * @uinfo: info to store
1866  *
1867  * This is a function that can be used as info callback for a standard
1868  * boolean control with stereo two channels.
1869  */
1870 int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
1871                                 struct snd_ctl_elem_info *uinfo)
1872 {
1873         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1874         uinfo->count = 2;
1875         uinfo->value.integer.min = 0;
1876         uinfo->value.integer.max = 1;
1877         return 0;
1878 }
1879 EXPORT_SYMBOL(snd_ctl_boolean_stereo_info);
1880
1881 /**
1882  * snd_ctl_enum_info - fills the info structure for an enumerated control
1883  * @info: the structure to be filled
1884  * @channels: the number of the control's channels; often one
1885  * @items: the number of control values; also the size of @names
1886  * @names: an array containing the names of all control values
1887  *
1888  * Sets all required fields in @info to their appropriate values.
1889  * If the control's accessibility is not the default (readable and writable),
1890  * the caller has to fill @info->access.
1891  *
1892  * Return: Zero.
1893  */
1894 int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
1895                       unsigned int items, const char *const names[])
1896 {
1897         info->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
1898         info->count = channels;
1899         info->value.enumerated.items = items;
1900         if (!items)
1901                 return 0;
1902         if (info->value.enumerated.item >= items)
1903                 info->value.enumerated.item = items - 1;
1904         WARN(strlen(names[info->value.enumerated.item]) >= sizeof(info->value.enumerated.name),
1905              "ALSA: too long item name '%s'\n",
1906              names[info->value.enumerated.item]);
1907         strlcpy(info->value.enumerated.name,
1908                 names[info->value.enumerated.item],
1909                 sizeof(info->value.enumerated.name));
1910         return 0;
1911 }
1912 EXPORT_SYMBOL(snd_ctl_enum_info);