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
 761         down_read(&card->controls_rwsem);
 762         list.count = card->controls_count;
 763         list.used = 0;
 764         if (space > 0) {
 765                 list_for_each_entry(kctl, &card->controls, list) {
 766                         if (offset >= kctl->count) {
 767                                 offset -= kctl->count;
 768                                 continue;
 769                         }
 770                         for (jidx = offset; jidx < kctl->count; jidx++) {
 771                                 snd_ctl_build_ioff(&id, kctl, jidx);
 772                                 if (copy_to_user(list.pids + list.used, &id,
 773                                                  sizeof(id))) {
 774                                         err = -EFAULT;
 775                                         goto out;
 776                                 }
 777                                 list.used++;
 778                                 if (!--space)
 779                                         goto out;
 780                         }
 781                         offset = 0;
 782                 }
 783         }
 784  out:
 785         up_read(&card->controls_rwsem);
 786         if (!err && copy_to_user(_list, &list, sizeof(list)))
 787                 err = -EFAULT;
 788         return err;
 789 }
 790
 791 static bool validate_element_member_dimension(struct snd_ctl_elem_info *info)
 792 {
 793         unsigned int members;
 794         unsigned int i;
 795
 796         if (info->dimen.d[0] == 0)
 797                 return true;
 798
 799         members = 1;
 800         for (i = 0; i < ARRAY_SIZE(info->dimen.d); ++i) {
 801                 if (info->dimen.d[i] == 0)
 802                         break;
 803                 members *= info->dimen.d[i];
 804
 805                 /*
 806                  * info->count should be validated in advance, to guarantee
 807                  * calculation soundness.
 808                  */
 809                 if (members > info->count)
 810                         return false;
 811         }
 812
 813         for (++i; i < ARRAY_SIZE(info->dimen.d); ++i) {
 814                 if (info->dimen.d[i] > 0)
 815                         return false;
 816         }
 817
 818         return members == info->count;
 819 }
 820
 821 static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
 822                              struct snd_ctl_elem_info *info)
 823 {
 824         struct snd_card *card = ctl->card;
 825         struct snd_kcontrol *kctl;
 826         struct snd_kcontrol_volatile *vd;
 827         unsigned int index_offset;
 828         int result;
 829
 830         down_read(&card->controls_rwsem);
 831         kctl = snd_ctl_find_id(card, &info->id);
 832         if (kctl == NULL) {
 833                 up_read(&card->controls_rwsem);
 834                 return -ENOENT;
 835         }
 836 #ifdef CONFIG_SND_DEBUG
 837         info->access = 0;
 838 #endif
 839         result = kctl->info(kctl, info);
 840         if (result >= 0) {
 841                 snd_BUG_ON(info->access);
 842                 index_offset = snd_ctl_get_ioff(kctl, &info->id);
 843                 vd = &kctl->vd[index_offset];
 844                 snd_ctl_build_ioff(&info->id, kctl, index_offset);
 845                 info->access = vd->access;
 846                 if (vd->owner) {
 847                         info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
 848                         if (vd->owner == ctl)
 849                                 info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
 850                         info->owner = pid_vnr(vd->owner->pid);
 851                 } else {
 852                         info->owner = -1;
 853                 }
 854         }
 855         up_read(&card->controls_rwsem);
 856         return result;
 857 }
 858
 859 static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
 860                                   struct snd_ctl_elem_info __user *_info)
 861 {
 862         struct snd_ctl_elem_info info;
 863         int result;
 864
 865         if (copy_from_user(&info, _info, sizeof(info)))
 866                 return -EFAULT;
 867         snd_power_lock(ctl->card);
 868         result = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);
 869         if (result >= 0)
 870                 result = snd_ctl_elem_info(ctl, &info);
 871         snd_power_unlock(ctl->card);
 872         if (result >= 0)
 873                 if (copy_to_user(_info, &info, sizeof(info)))
 874                         return -EFAULT;
 875         return result;
 876 }
 877
 878 static int snd_ctl_elem_read(struct snd_card *card,
 879                              struct snd_ctl_elem_value *control)
 880 {
 881         struct snd_kcontrol *kctl;
 882         struct snd_kcontrol_volatile *vd;
 883         unsigned int index_offset;
 884         int result;
 885
 886         down_read(&card->controls_rwsem);
 887         kctl = snd_ctl_find_id(card, &control->id);
 888         if (kctl == NULL) {
 889                 result = -ENOENT;
 890         } else {
 891                 index_offset = snd_ctl_get_ioff(kctl, &control->id);
 892                 vd = &kctl->vd[index_offset];
 893                 if ((vd->access & SNDRV_CTL_ELEM_ACCESS_READ) &&
 894                     kctl->get != NULL) {
 895                         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 896                         result = kctl->get(kctl, control);
 897                 } else
 898                         result = -EPERM;
 899         }
 900         up_read(&card->controls_rwsem);
 901         return result;
 902 }
 903
 904 static int snd_ctl_elem_read_user(struct snd_card *card,
 905                                   struct snd_ctl_elem_value __user *_control)
 906 {
 907         struct snd_ctl_elem_value *control;
 908         int result;
 909
 910         control = memdup_user(_control, sizeof(*control));
 911         if (IS_ERR(control))
 912                 return PTR_ERR(control);
 913
 914         snd_power_lock(card);
 915         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 916         if (result >= 0)
 917                 result = snd_ctl_elem_read(card, control);
 918         snd_power_unlock(card);
 919         if (result >= 0)
 920                 if (copy_to_user(_control, control, sizeof(*control)))
 921                         result = -EFAULT;
 922         kfree(control);
 923         return result;
 924 }
 925
 926 static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
 927                               struct snd_ctl_elem_value *control)
 928 {
 929         struct snd_kcontrol *kctl;
 930         struct snd_kcontrol_volatile *vd;
 931         unsigned int index_offset;
 932         int result;
 933
 934         down_read(&card->controls_rwsem);
 935         kctl = snd_ctl_find_id(card, &control->id);
 936         if (kctl == NULL) {
 937                 result = -ENOENT;
 938         } else {
 939                 index_offset = snd_ctl_get_ioff(kctl, &control->id);
 940                 vd = &kctl->vd[index_offset];
 941                 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_WRITE) ||
 942                     kctl->put == NULL ||
 943                     (file && vd->owner && vd->owner != file)) {
 944                         result = -EPERM;
 945                 } else {
 946                         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 947                         result = kctl->put(kctl, control);
 948                 }
 949                 if (result > 0) {
 950                         struct snd_ctl_elem_id id = control->id;
 951                         up_read(&card->controls_rwsem);
 952                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, &id);
 953                         return 0;
 954                 }
 955         }
 956         up_read(&card->controls_rwsem);
 957         return result;
 958 }
 959
 960 static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
 961                                    struct snd_ctl_elem_value __user *_control)
 962 {
 963         struct snd_ctl_elem_value *control;
 964         struct snd_card *card;
 965         int result;
 966
 967         control = memdup_user(_control, sizeof(*control));
 968         if (IS_ERR(control))
 969                 return PTR_ERR(control);
 970
 971         card = file->card;
 972         snd_power_lock(card);
 973         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 974         if (result >= 0)
 975                 result = snd_ctl_elem_write(card, file, control);
 976         snd_power_unlock(card);
 977         if (result >= 0)
 978                 if (copy_to_user(_control, control, sizeof(*control)))
 979                         result = -EFAULT;
 980         kfree(control);
 981         return result;
 982 }
 983
 984 static int snd_ctl_elem_lock(struct snd_ctl_file *file,
 985                              struct snd_ctl_elem_id __user *_id)
 986 {
 987         struct snd_card *card = file->card;
 988         struct snd_ctl_elem_id id;
 989         struct snd_kcontrol *kctl;
 990         struct snd_kcontrol_volatile *vd;
 991         int result;
 992
 993         if (copy_from_user(&id, _id, sizeof(id)))
 994                 return -EFAULT;
 995         down_write(&card->controls_rwsem);
 996         kctl = snd_ctl_find_id(card, &id);
 997         if (kctl == NULL) {
 998                 result = -ENOENT;
 999         } else {
1000                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1001                 if (vd->owner != NULL)
1002                         result = -EBUSY;
1003                 else {
1004                         vd->owner = file;
1005                         result = 0;
1006                 }
1007         }
1008         up_write(&card->controls_rwsem);
1009         return result;
1010 }
1011
1012 static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
1013                                struct snd_ctl_elem_id __user *_id)
1014 {
1015         struct snd_card *card = file->card;
1016         struct snd_ctl_elem_id id;
1017         struct snd_kcontrol *kctl;
1018         struct snd_kcontrol_volatile *vd;
1019         int result;
1020
1021         if (copy_from_user(&id, _id, sizeof(id)))
1022                 return -EFAULT;
1023         down_write(&card->controls_rwsem);
1024         kctl = snd_ctl_find_id(card, &id);
1025         if (kctl == NULL) {
1026                 result = -ENOENT;
1027         } else {
1028                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1029                 if (vd->owner == NULL)
1030                         result = -EINVAL;
1031                 else if (vd->owner != file)
1032                         result = -EPERM;
1033                 else {
1034                         vd->owner = NULL;
1035                         result = 0;
1036                 }
1037         }
1038         up_write(&card->controls_rwsem);
1039         return result;
1040 }
1041
1042 struct user_element {
1043         struct snd_ctl_elem_info info;
1044         struct snd_card *card;
1045         char *elem_data;                /* element data */
1046         unsigned long elem_data_size;   /* size of element data in bytes */
1047         void *tlv_data;                 /* TLV data */
1048         unsigned long tlv_data_size;    /* TLV data size */
1049         void *priv_data;                /* private data (like strings for enumerated type) */
1050 };
1051
1052 static int snd_ctl_elem_user_info(struct snd_kcontrol *kcontrol,
1053                                   struct snd_ctl_elem_info *uinfo)
1054 {
1055         struct user_element *ue = kcontrol->private_data;
1056         unsigned int offset;
1057
1058         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1059         *uinfo = ue->info;
1060         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1061
1062         return 0;
1063 }
1064
1065 static int snd_ctl_elem_user_enum_info(struct snd_kcontrol *kcontrol,
1066                                        struct snd_ctl_elem_info *uinfo)
1067 {
1068         struct user_element *ue = kcontrol->private_data;
1069         const char *names;
1070         unsigned int item;
1071         unsigned int offset;
1072
1073         item = uinfo->value.enumerated.item;
1074
1075         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1076         *uinfo = ue->info;
1077         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1078
1079         item = min(item, uinfo->value.enumerated.items - 1);
1080         uinfo->value.enumerated.item = item;
1081
1082         names = ue->priv_data;
1083         for (; item > 0; --item)
1084                 names += strlen(names) + 1;
1085         strcpy(uinfo->value.enumerated.name, names);
1086
1087         return 0;
1088 }
1089
1090 static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
1091                                  struct snd_ctl_elem_value *ucontrol)
1092 {
1093         struct user_element *ue = kcontrol->private_data;
1094         unsigned int size = ue->elem_data_size;
1095         char *src = ue->elem_data +
1096                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1097
1098         mutex_lock(&ue->card->user_ctl_lock);
1099         memcpy(&ucontrol->value, src, size);
1100         mutex_unlock(&ue->card->user_ctl_lock);
1101         return 0;
1102 }
1103
1104 static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
1105                                  struct snd_ctl_elem_value *ucontrol)
1106 {
1107         int change;
1108         struct user_element *ue = kcontrol->private_data;
1109         unsigned int size = ue->elem_data_size;
1110         char *dst = ue->elem_data +
1111                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1112
1113         mutex_lock(&ue->card->user_ctl_lock);
1114         change = memcmp(&ucontrol->value, dst, size) != 0;
1115         if (change)
1116                 memcpy(dst, &ucontrol->value, size);
1117         mutex_unlock(&ue->card->user_ctl_lock);
1118         return change;
1119 }
1120
1121 static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol,
1122                                  int op_flag,
1123                                  unsigned int size,
1124                                  unsigned int __user *tlv)
1125 {
1126         struct user_element *ue = kcontrol->private_data;
1127         int change = 0;
1128         void *new_data;
1129
1130         if (op_flag == SNDRV_CTL_TLV_OP_WRITE) {
1131                 if (size > 1024 * 128)  /* sane value */
1132                         return -EINVAL;
1133
1134                 new_data = memdup_user(tlv, size);
1135                 if (IS_ERR(new_data))
1136                         return PTR_ERR(new_data);
1137                 mutex_lock(&ue->card->user_ctl_lock);
1138                 change = ue->tlv_data_size != size;
1139                 if (!change)
1140                         change = memcmp(ue->tlv_data, new_data, size);
1141                 kfree(ue->tlv_data);
1142                 ue->tlv_data = new_data;
1143                 ue->tlv_data_size = size;
1144                 mutex_unlock(&ue->card->user_ctl_lock);
1145         } else {
1146                 int ret = 0;
1147
1148                 mutex_lock(&ue->card->user_ctl_lock);
1149                 if (!ue->tlv_data_size || !ue->tlv_data) {
1150                         ret = -ENXIO;
1151                         goto err_unlock;
1152                 }
1153                 if (size < ue->tlv_data_size) {
1154                         ret = -ENOSPC;
1155                         goto err_unlock;
1156                 }
1157                 if (copy_to_user(tlv, ue->tlv_data, ue->tlv_data_size))
1158                         ret = -EFAULT;
1159 err_unlock:
1160                 mutex_unlock(&ue->card->user_ctl_lock);
1161                 if (ret)
1162                         return ret;
1163         }
1164         return change;
1165 }
1166
1167 static int snd_ctl_elem_init_enum_names(struct user_element *ue)
1168 {
1169         char *names, *p;
1170         size_t buf_len, name_len;
1171         unsigned int i;
1172         const uintptr_t user_ptrval = ue->info.value.enumerated.names_ptr;
1173
1174         if (ue->info.value.enumerated.names_length > 64 * 1024)
1175                 return -EINVAL;
1176
1177         names = memdup_user((const void __user *)user_ptrval,
1178                 ue->info.value.enumerated.names_length);
1179         if (IS_ERR(names))
1180                 return PTR_ERR(names);
1181
1182         /* check that there are enough valid names */
1183         buf_len = ue->info.value.enumerated.names_length;
1184         p = names;
1185         for (i = 0; i < ue->info.value.enumerated.items; ++i) {
1186                 name_len = strnlen(p, buf_len);
1187                 if (name_len == 0 || name_len >= 64 || name_len == buf_len) {
1188                         kfree(names);
1189                         return -EINVAL;
1190                 }
1191                 p += name_len + 1;
1192                 buf_len -= name_len + 1;
1193         }
1194
1195         ue->priv_data = names;
1196         ue->info.value.enumerated.names_ptr = 0;
1197
1198         return 0;
1199 }
1200
1201 static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)
1202 {
1203         struct user_element *ue = kcontrol->private_data;
1204
1205         kfree(ue->tlv_data);
1206         kfree(ue->priv_data);
1207         kfree(ue);
1208 }
1209
1210 static int snd_ctl_elem_add(struct snd_ctl_file *file,
1211                             struct snd_ctl_elem_info *info, int replace)
1212 {
1213         /* The capacity of struct snd_ctl_elem_value.value.*/
1214         static const unsigned int value_sizes[] = {
1215                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = sizeof(long),
1216                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = sizeof(long),
1217                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = sizeof(unsigned int),
1218                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = sizeof(unsigned char),
1219                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = sizeof(struct snd_aes_iec958),
1220                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = sizeof(long long),
1221         };
1222         static const unsigned int max_value_counts[] = {
1223                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = 128,
1224                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = 128,
1225                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = 128,
1226                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = 512,
1227                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = 1,
1228                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = 64,
1229         };
1230         struct snd_card *card = file->card;
1231         struct snd_kcontrol *kctl;
1232         unsigned int count;
1233         unsigned int access;
1234         long private_size;
1235         struct user_element *ue;
1236         unsigned int offset;
1237         int err;
1238
1239         if (!*info->id.name)
1240                 return -EINVAL;
1241         if (strnlen(info->id.name, sizeof(info->id.name)) >= sizeof(info->id.name))
1242                 return -EINVAL;
1243
1244         /* Delete a control to replace them if needed. */
1245         if (replace) {
1246                 info->id.numid = 0;
1247                 err = snd_ctl_remove_user_ctl(file, &info->id);
1248                 if (err)
1249                         return err;
1250         }
1251
1252         /*
1253          * The number of userspace controls are counted control by control,
1254          * not element by element.
1255          */
1256         if (card->user_ctl_count + 1 > MAX_USER_CONTROLS)
1257                 return -ENOMEM;
1258
1259         /* Check the number of elements for this userspace control. */
1260         count = info->owner;
1261         if (count == 0)
1262                 count = 1;
1263
1264         /* Arrange access permissions if needed. */
1265         access = info->access;
1266         if (access == 0)
1267                 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
1268         access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
1269                    SNDRV_CTL_ELEM_ACCESS_INACTIVE |
1270                    SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE);
1271         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE)
1272                 access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
1273         access |= SNDRV_CTL_ELEM_ACCESS_USER;
1274
1275         /*
1276          * Check information and calculate the size of data specific to
1277          * this userspace control.
1278          */
1279         if (info->type < SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
1280             info->type > SNDRV_CTL_ELEM_TYPE_INTEGER64)
1281                 return -EINVAL;
1282         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED &&
1283             info->value.enumerated.items == 0)
1284                 return -EINVAL;
1285         if (info->count < 1 ||
1286             info->count > max_value_counts[info->type])
1287                 return -EINVAL;
1288         if (!validate_element_member_dimension(info))
1289                 return -EINVAL;
1290         private_size = value_sizes[info->type] * info->count;
1291
1292         /*
1293          * Keep memory object for this userspace control. After passing this
1294          * code block, the instance should be freed by snd_ctl_free_one().
1295          *
1296          * Note that these elements in this control are locked.
1297          */
1298         err = snd_ctl_new(&kctl, count, access, file);
1299         if (err < 0)
1300                 return err;
1301         memcpy(&kctl->id, &info->id, sizeof(kctl->id));
1302         kctl->private_data = kzalloc(sizeof(struct user_element) + private_size * count,
1303                                      GFP_KERNEL);
1304         if (kctl->private_data == NULL) {
1305                 kfree(kctl);
1306                 return -ENOMEM;
1307         }
1308         kctl->private_free = snd_ctl_elem_user_free;
1309
1310         /* Set private data for this userspace control. */
1311         ue = (struct user_element *)kctl->private_data;
1312         ue->card = card;
1313         ue->info = *info;
1314         ue->info.access = 0;
1315         ue->elem_data = (char *)ue + sizeof(*ue);
1316         ue->elem_data_size = private_size;
1317         if (ue->info.type == SNDRV_CTL_ELEM_TYPE_ENUMERATED) {
1318                 err = snd_ctl_elem_init_enum_names(ue);
1319                 if (err < 0) {
1320                         snd_ctl_free_one(kctl);
1321                         return err;
1322                 }
1323         }
1324
1325         /* Set callback functions. */
1326         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
1327                 kctl->info = snd_ctl_elem_user_enum_info;
1328         else
1329                 kctl->info = snd_ctl_elem_user_info;
1330         if (access & SNDRV_CTL_ELEM_ACCESS_READ)
1331                 kctl->get = snd_ctl_elem_user_get;
1332         if (access & SNDRV_CTL_ELEM_ACCESS_WRITE)
1333                 kctl->put = snd_ctl_elem_user_put;
1334         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE)
1335                 kctl->tlv.c = snd_ctl_elem_user_tlv;
1336
1337         /* This function manage to free the instance on failure. */
1338         err = snd_ctl_add(card, kctl);
1339         if (err < 0)
1340                 return err;
1341         offset = snd_ctl_get_ioff(kctl, &info->id);
1342         snd_ctl_build_ioff(&info->id, kctl, offset);
1343         /*
1344          * Here we cannot fill any field for the number of elements added by
1345          * this operation because there're no specific fields. The usage of
1346          * 'owner' field for this purpose may cause any bugs to userspace
1347          * applications because the field originally means PID of a process
1348          * which locks the element.
1349          */
1350
1351         down_write(&card->controls_rwsem);
1352         card->user_ctl_count++;
1353         up_write(&card->controls_rwsem);
1354
1355         return 0;
1356 }
1357
1358 static int snd_ctl_elem_add_user(struct snd_ctl_file *file,
1359                                  struct snd_ctl_elem_info __user *_info, int replace)
1360 {
1361         struct snd_ctl_elem_info info;
1362         int err;
1363
1364         if (copy_from_user(&info, _info, sizeof(info)))
1365                 return -EFAULT;
1366         err = snd_ctl_elem_add(file, &info, replace);
1367         if (err < 0)
1368                 return err;
1369         if (copy_to_user(_info, &info, sizeof(info))) {
1370                 snd_ctl_remove_user_ctl(file, &info.id);
1371                 return -EFAULT;
1372         }
1373
1374         return 0;
1375 }
1376
1377 static int snd_ctl_elem_remove(struct snd_ctl_file *file,
1378                                struct snd_ctl_elem_id __user *_id)
1379 {
1380         struct snd_ctl_elem_id id;
1381
1382         if (copy_from_user(&id, _id, sizeof(id)))
1383                 return -EFAULT;
1384         return snd_ctl_remove_user_ctl(file, &id);
1385 }
1386
1387 static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
1388 {
1389         int subscribe;
1390         if (get_user(subscribe, ptr))
1391                 return -EFAULT;
1392         if (subscribe < 0) {
1393                 subscribe = file->subscribed;
1394                 if (put_user(subscribe, ptr))
1395                         return -EFAULT;
1396                 return 0;
1397         }
1398         if (subscribe) {
1399                 file->subscribed = 1;
1400                 return 0;
1401         } else if (file->subscribed) {
1402                 snd_ctl_empty_read_queue(file);
1403                 file->subscribed = 0;
1404         }
1405         return 0;
1406 }
1407
1408 static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
1409                              struct snd_ctl_tlv __user *_tlv,
1410                              int op_flag)
1411 {
1412         struct snd_card *card = file->card;
1413         struct snd_ctl_tlv tlv;
1414         struct snd_kcontrol *kctl;
1415         struct snd_kcontrol_volatile *vd;
1416         unsigned int len;
1417         int err = 0;
1418
1419         if (copy_from_user(&tlv, _tlv, sizeof(tlv)))
1420                 return -EFAULT;
1421         if (tlv.length < sizeof(unsigned int) * 2)
1422                 return -EINVAL;
1423         if (!tlv.numid)
1424                 return -EINVAL;
1425         down_read(&card->controls_rwsem);
1426         kctl = snd_ctl_find_numid(card, tlv.numid);
1427         if (kctl == NULL) {
1428                 err = -ENOENT;
1429                 goto __kctl_end;
1430         }
1431         if (kctl->tlv.p == NULL) {
1432                 err = -ENXIO;
1433                 goto __kctl_end;
1434         }
1435         vd = &kctl->vd[tlv.numid - kctl->id.numid];
1436         if ((op_flag == SNDRV_CTL_TLV_OP_READ &&
1437              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ) == 0) ||
1438             (op_flag == SNDRV_CTL_TLV_OP_WRITE &&
1439              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE) == 0) ||
1440             (op_flag == SNDRV_CTL_TLV_OP_CMD &&
1441              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND) == 0)) {
1442                 err = -ENXIO;
1443                 goto __kctl_end;
1444         }
1445         if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
1446                 if (vd->owner != NULL && vd->owner != file) {
1447                         err = -EPERM;
1448                         goto __kctl_end;
1449                 }
1450                 err = kctl->tlv.c(kctl, op_flag, tlv.length, _tlv->tlv);
1451                 if (err > 0) {
1452                         struct snd_ctl_elem_id id = kctl->id;
1453                         up_read(&card->controls_rwsem);
1454                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_TLV, &id);
1455                         return 0;
1456                 }
1457         } else {
1458                 if (op_flag != SNDRV_CTL_TLV_OP_READ) {
1459                         err = -ENXIO;
1460                         goto __kctl_end;
1461                 }
1462                 len = kctl->tlv.p[1] + 2 * sizeof(unsigned int);
1463                 if (tlv.length < len) {
1464                         err = -ENOMEM;
1465                         goto __kctl_end;
1466                 }
1467                 if (copy_to_user(_tlv->tlv, kctl->tlv.p, len))
1468                         err = -EFAULT;
1469         }
1470       __kctl_end:
1471         up_read(&card->controls_rwsem);
1472         return err;
1473 }
1474
1475 static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1476 {
1477         struct snd_ctl_file *ctl;
1478         struct snd_card *card;
1479         struct snd_kctl_ioctl *p;
1480         void __user *argp = (void __user *)arg;
1481         int __user *ip = argp;
1482         int err;
1483
1484         ctl = file->private_data;
1485         card = ctl->card;
1486         if (snd_BUG_ON(!card))
1487                 return -ENXIO;
1488         switch (cmd) {
1489         case SNDRV_CTL_IOCTL_PVERSION:
1490                 return put_user(SNDRV_CTL_VERSION, ip) ? -EFAULT : 0;
1491         case SNDRV_CTL_IOCTL_CARD_INFO:
1492                 return snd_ctl_card_info(card, ctl, cmd, argp);
1493         case SNDRV_CTL_IOCTL_ELEM_LIST:
1494                 return snd_ctl_elem_list(card, argp);
1495         case SNDRV_CTL_IOCTL_ELEM_INFO:
1496                 return snd_ctl_elem_info_user(ctl, argp);
1497         case SNDRV_CTL_IOCTL_ELEM_READ:
1498                 return snd_ctl_elem_read_user(card, argp);
1499         case SNDRV_CTL_IOCTL_ELEM_WRITE:
1500                 return snd_ctl_elem_write_user(ctl, argp);
1501         case SNDRV_CTL_IOCTL_ELEM_LOCK:
1502                 return snd_ctl_elem_lock(ctl, argp);
1503         case SNDRV_CTL_IOCTL_ELEM_UNLOCK:
1504                 return snd_ctl_elem_unlock(ctl, argp);
1505         case SNDRV_CTL_IOCTL_ELEM_ADD:
1506                 return snd_ctl_elem_add_user(ctl, argp, 0);
1507         case SNDRV_CTL_IOCTL_ELEM_REPLACE:
1508                 return snd_ctl_elem_add_user(ctl, argp, 1);
1509         case SNDRV_CTL_IOCTL_ELEM_REMOVE:
1510                 return snd_ctl_elem_remove(ctl, argp);
1511         case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
1512                 return snd_ctl_subscribe_events(ctl, ip);
1513         case SNDRV_CTL_IOCTL_TLV_READ:
1514                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_READ);
1515         case SNDRV_CTL_IOCTL_TLV_WRITE:
1516                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_WRITE);
1517         case SNDRV_CTL_IOCTL_TLV_COMMAND:
1518                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_CMD);
1519         case SNDRV_CTL_IOCTL_POWER:
1520                 return -ENOPROTOOPT;
1521         case SNDRV_CTL_IOCTL_POWER_STATE:
1522 #ifdef CONFIG_PM
1523                 return put_user(card->power_state, ip) ? -EFAULT : 0;
1524 #else
1525                 return put_user(SNDRV_CTL_POWER_D0, ip) ? -EFAULT : 0;
1526 #endif
1527         }
1528         down_read(&snd_ioctl_rwsem);
1529         list_for_each_entry(p, &snd_control_ioctls, list) {
1530                 err = p->fioctl(card, ctl, cmd, arg);
1531                 if (err != -ENOIOCTLCMD) {
1532                         up_read(&snd_ioctl_rwsem);
1533                         return err;
1534                 }
1535         }
1536         up_read(&snd_ioctl_rwsem);
1537         dev_dbg(card->dev, "unknown ioctl = 0x%x\n", cmd);
1538         return -ENOTTY;
1539 }
1540
1541 static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
1542                             size_t count, loff_t * offset)
1543 {
1544         struct snd_ctl_file *ctl;
1545         int err = 0;
1546         ssize_t result = 0;
1547
1548         ctl = file->private_data;
1549         if (snd_BUG_ON(!ctl || !ctl->card))
1550                 return -ENXIO;
1551         if (!ctl->subscribed)
1552                 return -EBADFD;
1553         if (count < sizeof(struct snd_ctl_event))
1554                 return -EINVAL;
1555         spin_lock_irq(&ctl->read_lock);
1556         while (count >= sizeof(struct snd_ctl_event)) {
1557                 struct snd_ctl_event ev;
1558                 struct snd_kctl_event *kev;
1559                 while (list_empty(&ctl->events)) {
1560                         wait_queue_entry_t wait;
1561                         if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
1562                                 err = -EAGAIN;
1563                                 goto __end_lock;
1564                         }
1565                         init_waitqueue_entry(&wait, current);
1566                         add_wait_queue(&ctl->change_sleep, &wait);
1567                         set_current_state(TASK_INTERRUPTIBLE);
1568                         spin_unlock_irq(&ctl->read_lock);
1569                         schedule();
1570                         remove_wait_queue(&ctl->change_sleep, &wait);
1571                         if (ctl->card->shutdown)
1572                                 return -ENODEV;
1573                         if (signal_pending(current))
1574                                 return -ERESTARTSYS;
1575                         spin_lock_irq(&ctl->read_lock);
1576                 }
1577                 kev = snd_kctl_event(ctl->events.next);
1578                 ev.type = SNDRV_CTL_EVENT_ELEM;
1579                 ev.data.elem.mask = kev->mask;
1580                 ev.data.elem.id = kev->id;
1581                 list_del(&kev->list);
1582                 spin_unlock_irq(&ctl->read_lock);
1583                 kfree(kev);
1584                 if (copy_to_user(buffer, &ev, sizeof(struct snd_ctl_event))) {
1585                         err = -EFAULT;
1586                         goto __end;
1587                 }
1588                 spin_lock_irq(&ctl->read_lock);
1589                 buffer += sizeof(struct snd_ctl_event);
1590                 count -= sizeof(struct snd_ctl_event);
1591                 result += sizeof(struct snd_ctl_event);
1592         }
1593       __end_lock:
1594         spin_unlock_irq(&ctl->read_lock);
1595       __end:
1596         return result > 0 ? result : err;
1597 }
1598
1599 static unsigned int snd_ctl_poll(struct file *file, poll_table * wait)
1600 {
1601         unsigned int mask;
1602         struct snd_ctl_file *ctl;
1603
1604         ctl = file->private_data;
1605         if (!ctl->subscribed)
1606                 return 0;
1607         poll_wait(file, &ctl->change_sleep, wait);
1608
1609         mask = 0;
1610         if (!list_empty(&ctl->events))
1611                 mask |= POLLIN | POLLRDNORM;
1612
1613         return mask;
1614 }
1615
1616 /*
1617  * register the device-specific control-ioctls.
1618  * called from each device manager like pcm.c, hwdep.c, etc.
1619  */
1620 static int _snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn, struct list_head *lists)
1621 {
1622         struct snd_kctl_ioctl *pn;
1623
1624         pn = kzalloc(sizeof(struct snd_kctl_ioctl), GFP_KERNEL);
1625         if (pn == NULL)
1626                 return -ENOMEM;
1627         pn->fioctl = fcn;
1628         down_write(&snd_ioctl_rwsem);
1629         list_add_tail(&pn->list, lists);
1630         up_write(&snd_ioctl_rwsem);
1631         return 0;
1632 }
1633
1634 /**
1635  * snd_ctl_register_ioctl - register the device-specific control-ioctls
1636  * @fcn: ioctl callback function
1637  *
1638  * called from each device manager like pcm.c, hwdep.c, etc.
1639  */
1640 int snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn)
1641 {
1642         return _snd_ctl_register_ioctl(fcn, &snd_control_ioctls);
1643 }
1644 EXPORT_SYMBOL(snd_ctl_register_ioctl);
1645
1646 #ifdef CONFIG_COMPAT
1647 /**
1648  * snd_ctl_register_ioctl_compat - register the device-specific 32bit compat
1649  * control-ioctls
1650  * @fcn: ioctl callback function
1651  */
1652 int snd_ctl_register_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1653 {
1654         return _snd_ctl_register_ioctl(fcn, &snd_control_compat_ioctls);
1655 }
1656 EXPORT_SYMBOL(snd_ctl_register_ioctl_compat);
1657 #endif
1658
1659 /*
1660  * de-register the device-specific control-ioctls.
1661  */
1662 static int _snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn,
1663                                      struct list_head *lists)
1664 {
1665         struct snd_kctl_ioctl *p;
1666
1667         if (snd_BUG_ON(!fcn))
1668                 return -EINVAL;
1669         down_write(&snd_ioctl_rwsem);
1670         list_for_each_entry(p, lists, list) {
1671                 if (p->fioctl == fcn) {
1672                         list_del(&p->list);
1673                         up_write(&snd_ioctl_rwsem);
1674                         kfree(p);
1675                         return 0;
1676                 }
1677         }
1678         up_write(&snd_ioctl_rwsem);
1679         snd_BUG();
1680         return -EINVAL;
1681 }
1682
1683 /**
1684  * snd_ctl_unregister_ioctl - de-register the device-specific control-ioctls
1685  * @fcn: ioctl callback function to unregister
1686  */
1687 int snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn)
1688 {
1689         return _snd_ctl_unregister_ioctl(fcn, &snd_control_ioctls);
1690 }
1691 EXPORT_SYMBOL(snd_ctl_unregister_ioctl);
1692
1693 #ifdef CONFIG_COMPAT
1694 /**
1695  * snd_ctl_unregister_ioctl - de-register the device-specific compat 32bit
1696  * control-ioctls
1697  * @fcn: ioctl callback function to unregister
1698  */
1699 int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1700 {
1701         return _snd_ctl_unregister_ioctl(fcn, &snd_control_compat_ioctls);
1702 }
1703 EXPORT_SYMBOL(snd_ctl_unregister_ioctl_compat);
1704 #endif
1705
1706 static int snd_ctl_fasync(int fd, struct file * file, int on)
1707 {
1708         struct snd_ctl_file *ctl;
1709
1710         ctl = file->private_data;
1711         return fasync_helper(fd, file, on, &ctl->fasync);
1712 }
1713
1714 /* return the preferred subdevice number if already assigned;
1715  * otherwise return -1
1716  */
1717 int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type)
1718 {
1719         struct snd_ctl_file *kctl;
1720         int subdevice = -1;
1721
1722         read_lock(&card->ctl_files_rwlock);
1723         list_for_each_entry(kctl, &card->ctl_files, list) {
1724                 if (kctl->pid == task_pid(current)) {
1725                         subdevice = kctl->preferred_subdevice[type];
1726                         if (subdevice != -1)
1727                                 break;
1728                 }
1729         }
1730         read_unlock(&card->ctl_files_rwlock);
1731         return subdevice;
1732 }
1733 EXPORT_SYMBOL_GPL(snd_ctl_get_preferred_subdevice);
1734
1735 /*
1736  * ioctl32 compat
1737  */
1738 #ifdef CONFIG_COMPAT
1739 #include "control_compat.c"
1740 #else
1741 #define snd_ctl_ioctl_compat    NULL
1742 #endif
1743
1744 /*
1745  *  INIT PART
1746  */
1747
1748 static const struct file_operations snd_ctl_f_ops =
1749 {
1750         .owner =        THIS_MODULE,
1751         .read =         snd_ctl_read,
1752         .open =         snd_ctl_open,
1753         .release =      snd_ctl_release,
1754         .llseek =       no_llseek,
1755         .poll =         snd_ctl_poll,
1756         .unlocked_ioctl =       snd_ctl_ioctl,
1757         .compat_ioctl = snd_ctl_ioctl_compat,
1758         .fasync =       snd_ctl_fasync,
1759 };
1760
1761 /*
1762  * registration of the control device
1763  */
1764 static int snd_ctl_dev_register(struct snd_device *device)
1765 {
1766         struct snd_card *card = device->device_data;
1767
1768         return snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
1769                                    &snd_ctl_f_ops, card, &card->ctl_dev);
1770 }
1771
1772 /*
1773  * disconnection of the control device
1774  */
1775 static int snd_ctl_dev_disconnect(struct snd_device *device)
1776 {
1777         struct snd_card *card = device->device_data;
1778         struct snd_ctl_file *ctl;
1779
1780         read_lock(&card->ctl_files_rwlock);
1781         list_for_each_entry(ctl, &card->ctl_files, list) {
1782                 wake_up(&ctl->change_sleep);
1783                 kill_fasync(&ctl->fasync, SIGIO, POLL_ERR);
1784         }
1785         read_unlock(&card->ctl_files_rwlock);
1786
1787         return snd_unregister_device(&card->ctl_dev);
1788 }
1789
1790 /*
1791  * free all controls
1792  */
1793 static int snd_ctl_dev_free(struct snd_device *device)
1794 {
1795         struct snd_card *card = device->device_data;
1796         struct snd_kcontrol *control;
1797
1798         down_write(&card->controls_rwsem);
1799         while (!list_empty(&card->controls)) {
1800                 control = snd_kcontrol(card->controls.next);
1801                 snd_ctl_remove(card, control);
1802         }
1803         up_write(&card->controls_rwsem);
1804         put_device(&card->ctl_dev);
1805         return 0;
1806 }
1807
1808 /*
1809  * create control core:
1810  * called from init.c
1811  */
1812 int snd_ctl_create(struct snd_card *card)
1813 {
1814         static struct snd_device_ops ops = {
1815                 .dev_free = snd_ctl_dev_free,
1816                 .dev_register = snd_ctl_dev_register,
1817                 .dev_disconnect = snd_ctl_dev_disconnect,
1818         };
1819         int err;
1820
1821         if (snd_BUG_ON(!card))
1822                 return -ENXIO;
1823         if (snd_BUG_ON(card->number < 0 || card->number >= SNDRV_CARDS))
1824                 return -ENXIO;
1825
1826         snd_device_initialize(&card->ctl_dev, card);
1827         dev_set_name(&card->ctl_dev, "controlC%d", card->number);
1828
1829         err = snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
1830         if (err < 0)
1831                 put_device(&card->ctl_dev);
1832         return err;
1833 }
1834
1835 /*
1836  * Frequently used control callbacks/helpers
1837  */
1838
1839 /**
1840  * snd_ctl_boolean_mono_info - Helper function for a standard boolean info
1841  * callback with a mono channel
1842  * @kcontrol: the kcontrol instance
1843  * @uinfo: info to store
1844  *
1845  * This is a function that can be used as info callback for a standard
1846  * boolean control with a single mono channel.
1847  */
1848 int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
1849                               struct snd_ctl_elem_info *uinfo)
1850 {
1851         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1852         uinfo->count = 1;
1853         uinfo->value.integer.min = 0;
1854         uinfo->value.integer.max = 1;
1855         return 0;
1856 }
1857 EXPORT_SYMBOL(snd_ctl_boolean_mono_info);
1858
1859 /**
1860  * snd_ctl_boolean_stereo_info - Helper function for a standard boolean info
1861  * callback with stereo two channels
1862  * @kcontrol: the kcontrol instance
1863  * @uinfo: info to store
1864  *
1865  * This is a function that can be used as info callback for a standard
1866  * boolean control with stereo two channels.
1867  */
1868 int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
1869                                 struct snd_ctl_elem_info *uinfo)
1870 {
1871         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1872         uinfo->count = 2;
1873         uinfo->value.integer.min = 0;
1874         uinfo->value.integer.max = 1;
1875         return 0;
1876 }
1877 EXPORT_SYMBOL(snd_ctl_boolean_stereo_info);
1878
1879 /**
1880  * snd_ctl_enum_info - fills the info structure for an enumerated control
1881  * @info: the structure to be filled
1882  * @channels: the number of the control's channels; often one
1883  * @items: the number of control values; also the size of @names
1884  * @names: an array containing the names of all control values
1885  *
1886  * Sets all required fields in @info to their appropriate values.
1887  * If the control's accessibility is not the default (readable and writable),
1888  * the caller has to fill @info->access.
1889  *
1890  * Return: Zero.
1891  */
1892 int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
1893                       unsigned int items, const char *const names[])
1894 {
1895         info->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
1896         info->count = channels;
1897         info->value.enumerated.items = items;
1898         if (!items)
1899                 return 0;
1900         if (info->value.enumerated.item >= items)
1901                 info->value.enumerated.item = items - 1;
1902         WARN(strlen(names[info->value.enumerated.item]) >= sizeof(info->value.enumerated.name),
1903              "ALSA: too long item name '%s'\n",
1904              names[info->value.enumerated.item]);
1905         strlcpy(info->value.enumerated.name,
1906                 names[info->value.enumerated.item],
1907                 sizeof(info->value.enumerated.name));
1908         return 0;
1909 }
1910 EXPORT_SYMBOL(snd_ctl_enum_info);