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