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