kernel/sound/core/control.c

   1 /*
   2  *  Routines for driver control interface
   3  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
   4  *
   5  *
   6  *   This program is free software; you can redistribute it and/or modify
   7  *   it under the terms of the GNU General Public License as published by
   8  *   the Free Software Foundation; either version 2 of the License, or
   9  *   (at your option) any later version.
  10  *
  11  *   This program is distributed in the hope that it will be useful,
  12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *   GNU General Public License for more details.
  15  *
  16  *   You should have received a copy of the GNU General Public License
  17  *   along with this program; if not, write to the Free Software
  18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  19  *
  20  */
  21
  22 #include <linux/threads.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/module.h>
  25 #include <linux/slab.h>
  26 #include <linux/vmalloc.h>
  27 #include <linux/time.h>
  28 #include <sound/core.h>
  29 #include <sound/minors.h>
  30 #include <sound/info.h>
  31 #include <sound/control.h>
  32
  33 /* max number of user-defined controls */
  34 #define MAX_USER_CONTROLS       32
  35 #define MAX_CONTROL_COUNT       1028
  36
  37 struct snd_kctl_ioctl {
  38         struct list_head list;          /* list of all ioctls */
  39         snd_kctl_ioctl_func_t fioctl;
  40 };
  41
  42 static DECLARE_RWSEM(snd_ioctl_rwsem);
  43 static LIST_HEAD(snd_control_ioctls);
  44 #ifdef CONFIG_COMPAT
  45 static LIST_HEAD(snd_control_compat_ioctls);
  46 #endif
  47
  48 static int snd_ctl_open(struct inode *inode, struct file *file)
  49 {
  50         unsigned long flags;
  51         struct snd_card *card;
  52         struct snd_ctl_file *ctl;
  53         int i, err;
  54
  55         err = nonseekable_open(inode, file);
  56         if (err < 0)
  57                 return err;
  58
  59         card = snd_lookup_minor_data(iminor(inode), SNDRV_DEVICE_TYPE_CONTROL);
  60         if (!card) {
  61                 err = -ENODEV;
  62                 goto __error1;
  63         }
  64         err = snd_card_file_add(card, file);
  65         if (err < 0) {
  66                 err = -ENODEV;
  67                 goto __error1;
  68         }
  69         if (!try_module_get(card->module)) {
  70                 err = -EFAULT;
  71                 goto __error2;
  72         }
  73         ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);
  74         if (ctl == NULL) {
  75                 err = -ENOMEM;
  76                 goto __error;
  77         }
  78         INIT_LIST_HEAD(&ctl->events);
  79         init_waitqueue_head(&ctl->change_sleep);
  80         spin_lock_init(&ctl->read_lock);
  81         ctl->card = card;
  82         for (i = 0; i < SND_CTL_SUBDEV_ITEMS; i++)
  83                 ctl->preferred_subdevice[i] = -1;
  84         ctl->pid = get_pid(task_pid(current));
  85         file->private_data = ctl;
  86         write_lock_irqsave(&card->ctl_files_rwlock, flags);
  87         list_add_tail(&ctl->list, &card->ctl_files);
  88         write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
  89         snd_card_unref(card);
  90         return 0;
  91
  92       __error:
  93         module_put(card->module);
  94       __error2:
  95         snd_card_file_remove(card, file);
  96       __error1:
  97         if (card)
  98                 snd_card_unref(card);
  99         return err;
 100 }
 101
 102 static void snd_ctl_empty_read_queue(struct snd_ctl_file * ctl)
 103 {
 104         unsigned long flags;
 105         struct snd_kctl_event *cread;
 106
 107         spin_lock_irqsave(&ctl->read_lock, flags);
 108         while (!list_empty(&ctl->events)) {
 109                 cread = snd_kctl_event(ctl->events.next);
 110                 list_del(&cread->list);
 111                 kfree(cread);
 112         }
 113         spin_unlock_irqrestore(&ctl->read_lock, flags);
 114 }
 115
 116 static int snd_ctl_release(struct inode *inode, struct file *file)
 117 {
 118         unsigned long flags;
 119         struct snd_card *card;
 120         struct snd_ctl_file *ctl;
 121         struct snd_kcontrol *control;
 122         unsigned int idx;
 123
 124         ctl = file->private_data;
 125         file->private_data = NULL;
 126         card = ctl->card;
 127         write_lock_irqsave(&card->ctl_files_rwlock, flags);
 128         list_del(&ctl->list);
 129         write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
 130         down_write(&card->controls_rwsem);
 131         list_for_each_entry(control, &card->controls, list)
 132                 for (idx = 0; idx < control->count; idx++)
 133                         if (control->vd[idx].owner == ctl)
 134                                 control->vd[idx].owner = NULL;
 135         up_write(&card->controls_rwsem);
 136         snd_ctl_empty_read_queue(ctl);
 137         put_pid(ctl->pid);
 138         kfree(ctl);
 139         module_put(card->module);
 140         snd_card_file_remove(card, file);
 141         return 0;
 142 }
 143
 144 /**
 145  * snd_ctl_notify - Send notification to user-space for a control change
 146  * @card: the card to send notification
 147  * @mask: the event mask, SNDRV_CTL_EVENT_*
 148  * @id: the ctl element id to send notification
 149  *
 150  * This function adds an event record with the given id and mask, appends
 151  * to the list and wakes up the user-space for notification.  This can be
 152  * called in the atomic context.
 153  */
 154 void snd_ctl_notify(struct snd_card *card, unsigned int mask,
 155                     struct snd_ctl_elem_id *id)
 156 {
 157         unsigned long flags;
 158         struct snd_ctl_file *ctl;
 159         struct snd_kctl_event *ev;
 160
 161         if (snd_BUG_ON(!card || !id))
 162                 return;
 163         read_lock(&card->ctl_files_rwlock);
 164 #if IS_ENABLED(CONFIG_SND_MIXER_OSS)
 165         card->mixer_oss_change_count++;
 166 #endif
 167         list_for_each_entry(ctl, &card->ctl_files, list) {
 168                 if (!ctl->subscribed)
 169                         continue;
 170                 spin_lock_irqsave(&ctl->read_lock, flags);
 171                 list_for_each_entry(ev, &ctl->events, list) {
 172                         if (ev->id.numid == id->numid) {
 173                                 ev->mask |= mask;
 174                                 goto _found;
 175                         }
 176                 }
 177                 ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
 178                 if (ev) {
 179                         ev->id = *id;
 180                         ev->mask = mask;
 181                         list_add_tail(&ev->list, &ctl->events);
 182                 } else {
 183                         dev_err(card->dev, "No memory available to allocate event\n");
 184                 }
 185         _found:
 186                 wake_up(&ctl->change_sleep);
 187                 spin_unlock_irqrestore(&ctl->read_lock, flags);
 188                 kill_fasync(&ctl->fasync, SIGIO, POLL_IN);
 189         }
 190         read_unlock(&card->ctl_files_rwlock);
 191 }
 192 EXPORT_SYMBOL(snd_ctl_notify);
 193
 194 /**
 195  * snd_ctl_new - create a new control instance with some elements
 196  * @kctl: the pointer to store new control instance
 197  * @count: the number of elements in this control
 198  * @access: the default access flags for elements in this control
 199  * @file: given when locking these elements
 200  *
 201  * Allocates a memory object for a new control instance. The instance has
 202  * elements as many as the given number (@count). Each element has given
 203  * access permissions (@access). Each element is locked when @file is given.
 204  *
 205  * Return: 0 on success, error code on failure
 206  */
 207 static int snd_ctl_new(struct snd_kcontrol **kctl, unsigned int count,
 208                        unsigned int access, struct snd_ctl_file *file)
 209 {
 210         unsigned int size;
 211         unsigned int idx;
 212
 213         if (count == 0 || count > MAX_CONTROL_COUNT)
 214                 return -EINVAL;
 215
 216         size  = sizeof(struct snd_kcontrol);
 217         size += sizeof(struct snd_kcontrol_volatile) * count;
 218
 219         *kctl = kzalloc(size, GFP_KERNEL);
 220         if (!*kctl)
 221                 return -ENOMEM;
 222
 223         for (idx = 0; idx < count; idx++) {
 224                 (*kctl)->vd[idx].access = access;
 225                 (*kctl)->vd[idx].owner = file;
 226         }
 227         (*kctl)->count = count;
 228
 229         return 0;
 230 }
 231
 232 /**
 233  * snd_ctl_new1 - create a control instance from the template
 234  * @ncontrol: the initialization record
 235  * @private_data: the private data to set
 236  *
 237  * Allocates a new struct snd_kcontrol instance and initialize from the given
 238  * template.  When the access field of ncontrol is 0, it's assumed as
 239  * READWRITE access. When the count field is 0, it's assumes as one.
 240  *
 241  * Return: The pointer of the newly generated instance, or %NULL on failure.
 242  */
 243 struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new *ncontrol,
 244                                   void *private_data)
 245 {
 246         struct snd_kcontrol *kctl;
 247         unsigned int count;
 248         unsigned int access;
 249         int err;
 250
 251         if (snd_BUG_ON(!ncontrol || !ncontrol->info))
 252                 return NULL;
 253
 254         count = ncontrol->count;
 255         if (count == 0)
 256                 count = 1;
 257
 258         access = ncontrol->access;
 259         if (access == 0)
 260                 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
 261         access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
 262                    SNDRV_CTL_ELEM_ACCESS_VOLATILE |
 263                    SNDRV_CTL_ELEM_ACCESS_INACTIVE |
 264                    SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE |
 265                    SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND |
 266                    SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
 267
 268         err = snd_ctl_new(&kctl, count, access, NULL);
 269         if (err < 0)
 270                 return NULL;
 271
 272         /* The 'numid' member is decided when calling snd_ctl_add(). */
 273         kctl->id.iface = ncontrol->iface;
 274         kctl->id.device = ncontrol->device;
 275         kctl->id.subdevice = ncontrol->subdevice;
 276         if (ncontrol->name) {
 277                 strlcpy(kctl->id.name, ncontrol->name, sizeof(kctl->id.name));
 278                 if (strcmp(ncontrol->name, kctl->id.name) != 0)
 279                         pr_warn("ALSA: Control name '%s' truncated to '%s'\n",
 280                                 ncontrol->name, kctl->id.name);
 281         }
 282         kctl->id.index = ncontrol->index;
 283
 284         kctl->info = ncontrol->info;
 285         kctl->get = ncontrol->get;
 286         kctl->put = ncontrol->put;
 287         kctl->tlv.p = ncontrol->tlv.p;
 288
 289         kctl->private_value = ncontrol->private_value;
 290         kctl->private_data = private_data;
 291
 292         return kctl;
 293 }
 294 EXPORT_SYMBOL(snd_ctl_new1);
 295
 296 /**
 297  * snd_ctl_free_one - release the control instance
 298  * @kcontrol: the control instance
 299  *
 300  * Releases the control instance created via snd_ctl_new()
 301  * or snd_ctl_new1().
 302  * Don't call this after the control was added to the card.
 303  */
 304 void snd_ctl_free_one(struct snd_kcontrol *kcontrol)
 305 {
 306         if (kcontrol) {
 307                 if (kcontrol->private_free)
 308                         kcontrol->private_free(kcontrol);
 309                 kfree(kcontrol);
 310         }
 311 }
 312 EXPORT_SYMBOL(snd_ctl_free_one);
 313
 314 static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
 315                                           unsigned int count)
 316 {
 317         struct snd_kcontrol *kctl;
 318
 319         /* Make sure that the ids assigned to the control do not wrap around */
 320         if (card->last_numid >= UINT_MAX - count)
 321                 card->last_numid = 0;
 322
 323         list_for_each_entry(kctl, &card->controls, list) {
 324                 if (kctl->id.numid < card->last_numid + 1 + count &&
 325                     kctl->id.numid + kctl->count > card->last_numid + 1) {
 326                         card->last_numid = kctl->id.numid + kctl->count - 1;
 327                         return true;
 328                 }
 329         }
 330         return false;
 331 }
 332
 333 static int snd_ctl_find_hole(struct snd_card *card, unsigned int count)
 334 {
 335         unsigned int iter = 100000;
 336
 337         while (snd_ctl_remove_numid_conflict(card, count)) {
 338                 if (--iter == 0) {
 339                         /* this situation is very unlikely */
 340                         dev_err(card->dev, "unable to allocate new control numid\n");
 341                         return -ENOMEM;
 342                 }
 343         }
 344         return 0;
 345 }
 346
 347 /**
 348  * snd_ctl_add - add the control instance to the card
 349  * @card: the card instance
 350  * @kcontrol: the control instance to add
 351  *
 352  * Adds the control instance created via snd_ctl_new() or
 353  * snd_ctl_new1() to the given card. Assigns also an unique
 354  * numid used for fast search.
 355  *
 356  * It frees automatically the control which cannot be added.
 357  *
 358  * Return: Zero if successful, or a negative error code on failure.
 359  *
 360  */
 361 int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
 362 {
 363         struct snd_ctl_elem_id id;
 364         unsigned int idx;
 365         unsigned int count;
 366         int err = -EINVAL;
 367
 368         if (! kcontrol)
 369                 return err;
 370         if (snd_BUG_ON(!card || !kcontrol->info))
 371                 goto error;
 372         id = kcontrol->id;
 373         if (id.index > UINT_MAX - kcontrol->count)
 374                 goto error;
 375
 376         down_write(&card->controls_rwsem);
 377         if (snd_ctl_find_id(card, &id)) {
 378                 up_write(&card->controls_rwsem);
 379                 dev_err(card->dev, "control %i:%i:%i:%s:%i is already present\n",
 380                                         id.iface,
 381                                         id.device,
 382                                         id.subdevice,
 383                                         id.name,
 384                                         id.index);
 385                 err = -EBUSY;
 386                 goto error;
 387         }
 388         if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
 389                 up_write(&card->controls_rwsem);
 390                 err = -ENOMEM;
 391                 goto error;
 392         }
 393         list_add_tail(&kcontrol->list, &card->controls);
 394         card->controls_count += kcontrol->count;
 395         kcontrol->id.numid = card->last_numid + 1;
 396         card->last_numid += kcontrol->count;
 397         id = kcontrol->id;
 398         count = kcontrol->count;
 399         up_write(&card->controls_rwsem);
 400         for (idx = 0; idx < count; idx++, id.index++, id.numid++)
 401                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
 402         return 0;
 403
 404  error:
 405         snd_ctl_free_one(kcontrol);
 406         return err;
 407 }
 408 EXPORT_SYMBOL(snd_ctl_add);
 409
 410 /**
 411  * snd_ctl_replace - replace the control instance of the card
 412  * @card: the card instance
 413  * @kcontrol: the control instance to replace
 414  * @add_on_replace: add the control if not already added
 415  *
 416  * Replaces the given control.  If the given control does not exist
 417  * and the add_on_replace flag is set, the control is added.  If the
 418  * control exists, it is destroyed first.
 419  *
 420  * It frees automatically the control which cannot be added or replaced.
 421  *
 422  * Return: Zero if successful, or a negative error code on failure.
 423  */
 424 int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
 425                     bool add_on_replace)
 426 {
 427         struct snd_ctl_elem_id id;
 428         unsigned int count;
 429         unsigned int idx;
 430         struct snd_kcontrol *old;
 431         int ret;
 432
 433         if (!kcontrol)
 434                 return -EINVAL;
 435         if (snd_BUG_ON(!card || !kcontrol->info)) {
 436                 ret = -EINVAL;
 437                 goto error;
 438         }
 439         id = kcontrol->id;
 440         down_write(&card->controls_rwsem);
 441         old = snd_ctl_find_id(card, &id);
 442         if (!old) {
 443                 if (add_on_replace)
 444                         goto add;
 445                 up_write(&card->controls_rwsem);
 446                 ret = -EINVAL;
 447                 goto error;
 448         }
 449         ret = snd_ctl_remove(card, old);
 450         if (ret < 0) {
 451                 up_write(&card->controls_rwsem);
 452                 goto error;
 453         }
 454 add:
 455         if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
 456                 up_write(&card->controls_rwsem);
 457                 ret = -ENOMEM;
 458                 goto error;
 459         }
 460         list_add_tail(&kcontrol->list, &card->controls);
 461         card->controls_count += kcontrol->count;
 462         kcontrol->id.numid = card->last_numid + 1;
 463         card->last_numid += kcontrol->count;
 464         id = kcontrol->id;
 465         count = kcontrol->count;
 466         up_write(&card->controls_rwsem);
 467         for (idx = 0; idx < count; idx++, id.index++, id.numid++)
 468                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
 469         return 0;
 470
 471 error:
 472         snd_ctl_free_one(kcontrol);
 473         return ret;
 474 }
 475 EXPORT_SYMBOL(snd_ctl_replace);
 476
 477 /**
 478  * snd_ctl_remove - remove the control from the card and release it
 479  * @card: the card instance
 480  * @kcontrol: the control instance to remove
 481  *
 482  * Removes the control from the card and then releases the instance.
 483  * You don't need to call snd_ctl_free_one(). You must be in
 484  * the write lock - down_write(&card->controls_rwsem).
 485  *
 486  * Return: 0 if successful, or a negative error code on failure.
 487  */
 488 int snd_ctl_remove(struct snd_card *card, struct snd_kcontrol *kcontrol)
 489 {
 490         struct snd_ctl_elem_id id;
 491         unsigned int idx;
 492
 493         if (snd_BUG_ON(!card || !kcontrol))
 494                 return -EINVAL;
 495         list_del(&kcontrol->list);
 496         card->controls_count -= kcontrol->count;
 497         id = kcontrol->id;
 498         for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
 499                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_REMOVE, &id);
 500         snd_ctl_free_one(kcontrol);
 501         return 0;
 502 }
 503 EXPORT_SYMBOL(snd_ctl_remove);
 504
 505 /**
 506  * snd_ctl_remove_id - remove the control of the given id and release it
 507  * @card: the card instance
 508  * @id: the control id to remove
 509  *
 510  * Finds the control instance with the given id, removes it from the
 511  * card list and releases it.
 512  *
 513  * Return: 0 if successful, or a negative error code on failure.
 514  */
 515 int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
 516 {
 517         struct snd_kcontrol *kctl;
 518         int ret;
 519
 520         down_write(&card->controls_rwsem);
 521         kctl = snd_ctl_find_id(card, id);
 522         if (kctl == NULL) {
 523                 up_write(&card->controls_rwsem);
 524                 return -ENOENT;
 525         }
 526         ret = snd_ctl_remove(card, kctl);
 527         up_write(&card->controls_rwsem);
 528         return ret;
 529 }
 530 EXPORT_SYMBOL(snd_ctl_remove_id);
 531
 532 /**
 533  * snd_ctl_remove_user_ctl - remove and release the unlocked user control
 534  * @file: active control handle
 535  * @id: the control id to remove
 536  *
 537  * Finds the control instance with the given id, removes it from the
 538  * card list and releases it.
 539  *
 540  * Return: 0 if successful, or a negative error code on failure.
 541  */
 542 static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
 543                                    struct snd_ctl_elem_id *id)
 544 {
 545         struct snd_card *card = file->card;
 546         struct snd_kcontrol *kctl;
 547         int idx, ret;
 548
 549         down_write(&card->controls_rwsem);
 550         kctl = snd_ctl_find_id(card, id);
 551         if (kctl == NULL) {
 552                 ret = -ENOENT;
 553                 goto error;
 554         }
 555         if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER)) {
 556                 ret = -EINVAL;
 557                 goto error;
 558         }
 559         for (idx = 0; idx < kctl->count; idx++)
 560                 if (kctl->vd[idx].owner != NULL && kctl->vd[idx].owner != file) {
 561                         ret = -EBUSY;
 562                         goto error;
 563                 }
 564         ret = snd_ctl_remove(card, kctl);
 565         if (ret < 0)
 566                 goto error;
 567         card->user_ctl_count--;
 568 error:
 569         up_write(&card->controls_rwsem);
 570         return ret;
 571 }
 572
 573 /**
 574  * snd_ctl_activate_id - activate/inactivate the control of the given id
 575  * @card: the card instance
 576  * @id: the control id to activate/inactivate
 577  * @active: non-zero to activate
 578  *
 579  * Finds the control instance with the given id, and activate or
 580  * inactivate the control together with notification, if changed.
 581  * The given ID data is filled with full information.
 582  *
 583  * Return: 0 if unchanged, 1 if changed, or a negative error code on failure.
 584  */
 585 int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
 586                         int active)
 587 {
 588         struct snd_kcontrol *kctl;
 589         struct snd_kcontrol_volatile *vd;
 590         unsigned int index_offset;
 591         int ret;
 592
 593         down_write(&card->controls_rwsem);
 594         kctl = snd_ctl_find_id(card, id);
 595         if (kctl == NULL) {
 596                 ret = -ENOENT;
 597                 goto unlock;
 598         }
 599         index_offset = snd_ctl_get_ioff(kctl, id);
 600         vd = &kctl->vd[index_offset];
 601         ret = 0;
 602         if (active) {
 603                 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
 604                         goto unlock;
 605                 vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
 606         } else {
 607                 if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
 608                         goto unlock;
 609                 vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
 610         }
 611         snd_ctl_build_ioff(id, kctl, index_offset);
 612         ret = 1;
 613  unlock:
 614         up_write(&card->controls_rwsem);
 615         if (ret > 0)
 616                 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, id);
 617         return ret;
 618 }
 619 EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
 620
 621 /**
 622  * snd_ctl_rename_id - replace the id of a control on the card
 623  * @card: the card instance
 624  * @src_id: the old id
 625  * @dst_id: the new id
 626  *
 627  * Finds the control with the old id from the card, and replaces the
 628  * id with the new one.
 629  *
 630  * Return: Zero if successful, or a negative error code on failure.
 631  */
 632 int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
 633                       struct snd_ctl_elem_id *dst_id)
 634 {
 635         struct snd_kcontrol *kctl;
 636
 637         down_write(&card->controls_rwsem);
 638         kctl = snd_ctl_find_id(card, src_id);
 639         if (kctl == NULL) {
 640                 up_write(&card->controls_rwsem);
 641                 return -ENOENT;
 642         }
 643         kctl->id = *dst_id;
 644         kctl->id.numid = card->last_numid + 1;
 645         card->last_numid += kctl->count;
 646         up_write(&card->controls_rwsem);
 647         return 0;
 648 }
 649 EXPORT_SYMBOL(snd_ctl_rename_id);
 650
 651 /**
 652  * snd_ctl_find_numid - find the control instance with the given number-id
 653  * @card: the card instance
 654  * @numid: the number-id to search
 655  *
 656  * Finds the control instance with the given number-id from the card.
 657  *
 658  * The caller must down card->controls_rwsem before calling this function
 659  * (if the race condition can happen).
 660  *
 661  * Return: The pointer of the instance if found, or %NULL if not.
 662  *
 663  */
 664 struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card, unsigned int numid)
 665 {
 666         struct snd_kcontrol *kctl;
 667
 668         if (snd_BUG_ON(!card || !numid))
 669                 return NULL;
 670         list_for_each_entry(kctl, &card->controls, list) {
 671                 if (kctl->id.numid <= numid && kctl->id.numid + kctl->count > numid)
 672                         return kctl;
 673         }
 674         return NULL;
 675 }
 676 EXPORT_SYMBOL(snd_ctl_find_numid);
 677
 678 /**
 679  * snd_ctl_find_id - find the control instance with the given id
 680  * @card: the card instance
 681  * @id: the id to search
 682  *
 683  * Finds the control instance with the given id from the card.
 684  *
 685  * The caller must down card->controls_rwsem before calling this function
 686  * (if the race condition can happen).
 687  *
 688  * Return: The pointer of the instance if found, or %NULL if not.
 689  *
 690  */
 691 struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
 692                                      struct snd_ctl_elem_id *id)
 693 {
 694         struct snd_kcontrol *kctl;
 695
 696         if (snd_BUG_ON(!card || !id))
 697                 return NULL;
 698         if (id->numid != 0)
 699                 return snd_ctl_find_numid(card, id->numid);
 700         list_for_each_entry(kctl, &card->controls, list) {
 701                 if (kctl->id.iface != id->iface)
 702                         continue;
 703                 if (kctl->id.device != id->device)
 704                         continue;
 705                 if (kctl->id.subdevice != id->subdevice)
 706                         continue;
 707                 if (strncmp(kctl->id.name, id->name, sizeof(kctl->id.name)))
 708                         continue;
 709                 if (kctl->id.index > id->index)
 710                         continue;
 711                 if (kctl->id.index + kctl->count <= id->index)
 712                         continue;
 713                 return kctl;
 714         }
 715         return NULL;
 716 }
 717 EXPORT_SYMBOL(snd_ctl_find_id);
 718
 719 static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,
 720                              unsigned int cmd, void __user *arg)
 721 {
 722         struct snd_ctl_card_info *info;
 723
 724         info = kzalloc(sizeof(*info), GFP_KERNEL);
 725         if (! info)
 726                 return -ENOMEM;
 727         down_read(&snd_ioctl_rwsem);
 728         info->card = card->number;
 729         strlcpy(info->id, card->id, sizeof(info->id));
 730         strlcpy(info->driver, card->driver, sizeof(info->driver));
 731         strlcpy(info->name, card->shortname, sizeof(info->name));
 732         strlcpy(info->longname, card->longname, sizeof(info->longname));
 733         strlcpy(info->mixername, card->mixername, sizeof(info->mixername));
 734         strlcpy(info->components, card->components, sizeof(info->components));
 735         up_read(&snd_ioctl_rwsem);
 736         if (copy_to_user(arg, info, sizeof(struct snd_ctl_card_info))) {
 737                 kfree(info);
 738                 return -EFAULT;
 739         }
 740         kfree(info);
 741         return 0;
 742 }
 743
 744 static int snd_ctl_elem_list(struct snd_card *card,
 745                              struct snd_ctl_elem_list __user *_list)
 746 {
 747         struct list_head *plist;
 748         struct snd_ctl_elem_list list;
 749         struct snd_kcontrol *kctl;
 750         struct snd_ctl_elem_id *dst, *id;
 751         unsigned int offset, space, jidx;
 752
 753         if (copy_from_user(&list, _list, sizeof(list)))
 754                 return -EFAULT;
 755         offset = list.offset;
 756         space = list.space;
 757         /* try limit maximum space */
 758         if (space > 16384)
 759                 return -ENOMEM;
 760         if (space > 0) {
 761                 /* allocate temporary buffer for atomic operation */
 762                 dst = vmalloc(space * sizeof(struct snd_ctl_elem_id));
 763                 if (dst == NULL)
 764                         return -ENOMEM;
 765                 down_read(&card->controls_rwsem);
 766                 list.count = card->controls_count;
 767                 plist = card->controls.next;
 768                 while (plist != &card->controls) {
 769                         if (offset == 0)
 770                                 break;
 771                         kctl = snd_kcontrol(plist);
 772                         if (offset < kctl->count)
 773                                 break;
 774                         offset -= kctl->count;
 775                         plist = plist->next;
 776                 }
 777                 list.used = 0;
 778                 id = dst;
 779                 while (space > 0 && plist != &card->controls) {
 780                         kctl = snd_kcontrol(plist);
 781                         for (jidx = offset; space > 0 && jidx < kctl->count; jidx++) {
 782                                 snd_ctl_build_ioff(id, kctl, jidx);
 783                                 id++;
 784                                 space--;
 785                                 list.used++;
 786                         }
 787                         plist = plist->next;
 788                         offset = 0;
 789                 }
 790                 up_read(&card->controls_rwsem);
 791                 if (list.used > 0 &&
 792                     copy_to_user(list.pids, dst,
 793                                  list.used * sizeof(struct snd_ctl_elem_id))) {
 794                         vfree(dst);
 795                         return -EFAULT;
 796                 }
 797                 vfree(dst);
 798         } else {
 799                 down_read(&card->controls_rwsem);
 800                 list.count = card->controls_count;
 801                 up_read(&card->controls_rwsem);
 802         }
 803         if (copy_to_user(_list, &list, sizeof(list)))
 804                 return -EFAULT;
 805         return 0;
 806 }
 807
 808 static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
 809                              struct snd_ctl_elem_info *info)
 810 {
 811         struct snd_card *card = ctl->card;
 812         struct snd_kcontrol *kctl;
 813         struct snd_kcontrol_volatile *vd;
 814         unsigned int index_offset;
 815         int result;
 816
 817         down_read(&card->controls_rwsem);
 818         kctl = snd_ctl_find_id(card, &info->id);
 819         if (kctl == NULL) {
 820                 up_read(&card->controls_rwsem);
 821                 return -ENOENT;
 822         }
 823 #ifdef CONFIG_SND_DEBUG
 824         info->access = 0;
 825 #endif
 826         result = kctl->info(kctl, info);
 827         if (result >= 0) {
 828                 snd_BUG_ON(info->access);
 829                 index_offset = snd_ctl_get_ioff(kctl, &info->id);
 830                 vd = &kctl->vd[index_offset];
 831                 snd_ctl_build_ioff(&info->id, kctl, index_offset);
 832                 info->access = vd->access;
 833                 if (vd->owner) {
 834                         info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
 835                         if (vd->owner == ctl)
 836                                 info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
 837                         info->owner = pid_vnr(vd->owner->pid);
 838                 } else {
 839                         info->owner = -1;
 840                 }
 841         }
 842         up_read(&card->controls_rwsem);
 843         return result;
 844 }
 845
 846 static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
 847                                   struct snd_ctl_elem_info __user *_info)
 848 {
 849         struct snd_ctl_elem_info info;
 850         int result;
 851
 852         if (copy_from_user(&info, _info, sizeof(info)))
 853                 return -EFAULT;
 854         snd_power_lock(ctl->card);
 855         result = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);
 856         if (result >= 0)
 857                 result = snd_ctl_elem_info(ctl, &info);
 858         snd_power_unlock(ctl->card);
 859         if (result >= 0)
 860                 if (copy_to_user(_info, &info, sizeof(info)))
 861                         return -EFAULT;
 862         return result;
 863 }
 864
 865 static int snd_ctl_elem_read(struct snd_card *card,
 866                              struct snd_ctl_elem_value *control)
 867 {
 868         struct snd_kcontrol *kctl;
 869         struct snd_kcontrol_volatile *vd;
 870         unsigned int index_offset;
 871         int result;
 872
 873         down_read(&card->controls_rwsem);
 874         kctl = snd_ctl_find_id(card, &control->id);
 875         if (kctl == NULL) {
 876                 result = -ENOENT;
 877         } else {
 878                 index_offset = snd_ctl_get_ioff(kctl, &control->id);
 879                 vd = &kctl->vd[index_offset];
 880                 if ((vd->access & SNDRV_CTL_ELEM_ACCESS_READ) &&
 881                     kctl->get != NULL) {
 882                         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 883                         result = kctl->get(kctl, control);
 884                 } else
 885                         result = -EPERM;
 886         }
 887         up_read(&card->controls_rwsem);
 888         return result;
 889 }
 890
 891 static int snd_ctl_elem_read_user(struct snd_card *card,
 892                                   struct snd_ctl_elem_value __user *_control)
 893 {
 894         struct snd_ctl_elem_value *control;
 895         int result;
 896
 897         control = memdup_user(_control, sizeof(*control));
 898         if (IS_ERR(control))
 899                 return PTR_ERR(control);
 900
 901         snd_power_lock(card);
 902         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 903         if (result >= 0)
 904                 result = snd_ctl_elem_read(card, control);
 905         snd_power_unlock(card);
 906         if (result >= 0)
 907                 if (copy_to_user(_control, control, sizeof(*control)))
 908                         result = -EFAULT;
 909         kfree(control);
 910         return result;
 911 }
 912
 913 static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
 914                               struct snd_ctl_elem_value *control)
 915 {
 916         struct snd_kcontrol *kctl;
 917         struct snd_kcontrol_volatile *vd;
 918         unsigned int index_offset;
 919         int result;
 920
 921         down_read(&card->controls_rwsem);
 922         kctl = snd_ctl_find_id(card, &control->id);
 923         if (kctl == NULL) {
 924                 result = -ENOENT;
 925         } else {
 926                 index_offset = snd_ctl_get_ioff(kctl, &control->id);
 927                 vd = &kctl->vd[index_offset];
 928                 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_WRITE) ||
 929                     kctl->put == NULL ||
 930                     (file && vd->owner && vd->owner != file)) {
 931                         result = -EPERM;
 932                 } else {
 933                         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 934                         result = kctl->put(kctl, control);
 935                 }
 936                 if (result > 0) {
 937                         struct snd_ctl_elem_id id = control->id;
 938                         up_read(&card->controls_rwsem);
 939                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, &id);
 940                         return 0;
 941                 }
 942         }
 943         up_read(&card->controls_rwsem);
 944         return result;
 945 }
 946
 947 static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
 948                                    struct snd_ctl_elem_value __user *_control)
 949 {
 950         struct snd_ctl_elem_value *control;
 951         struct snd_card *card;
 952         int result;
 953
 954         control = memdup_user(_control, sizeof(*control));
 955         if (IS_ERR(control))
 956                 return PTR_ERR(control);
 957
 958         card = file->card;
 959         snd_power_lock(card);
 960         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 961         if (result >= 0)
 962                 result = snd_ctl_elem_write(card, file, control);
 963         snd_power_unlock(card);
 964         if (result >= 0)
 965                 if (copy_to_user(_control, control, sizeof(*control)))
 966                         result = -EFAULT;
 967         kfree(control);
 968         return result;
 969 }
 970
 971 static int snd_ctl_elem_lock(struct snd_ctl_file *file,
 972                              struct snd_ctl_elem_id __user *_id)
 973 {
 974         struct snd_card *card = file->card;
 975         struct snd_ctl_elem_id id;
 976         struct snd_kcontrol *kctl;
 977         struct snd_kcontrol_volatile *vd;
 978         int result;
 979
 980         if (copy_from_user(&id, _id, sizeof(id)))
 981                 return -EFAULT;
 982         down_write(&card->controls_rwsem);
 983         kctl = snd_ctl_find_id(card, &id);
 984         if (kctl == NULL) {
 985                 result = -ENOENT;
 986         } else {
 987                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
 988                 if (vd->owner != NULL)
 989                         result = -EBUSY;
 990                 else {
 991                         vd->owner = file;
 992                         result = 0;
 993                 }
 994         }
 995         up_write(&card->controls_rwsem);
 996         return result;
 997 }
 998
 999 static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
1000                                struct snd_ctl_elem_id __user *_id)
1001 {
1002         struct snd_card *card = file->card;
1003         struct snd_ctl_elem_id id;
1004         struct snd_kcontrol *kctl;
1005         struct snd_kcontrol_volatile *vd;
1006         int result;
1007
1008         if (copy_from_user(&id, _id, sizeof(id)))
1009                 return -EFAULT;
1010         down_write(&card->controls_rwsem);
1011         kctl = snd_ctl_find_id(card, &id);
1012         if (kctl == NULL) {
1013                 result = -ENOENT;
1014         } else {
1015                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1016                 if (vd->owner == NULL)
1017                         result = -EINVAL;
1018                 else if (vd->owner != file)
1019                         result = -EPERM;
1020                 else {
1021                         vd->owner = NULL;
1022                         result = 0;
1023                 }
1024         }
1025         up_write(&card->controls_rwsem);
1026         return result;
1027 }
1028
1029 struct user_element {
1030         struct snd_ctl_elem_info info;
1031         struct snd_card *card;
1032         char *elem_data;                /* element data */
1033         unsigned long elem_data_size;   /* size of element data in bytes */
1034         void *tlv_data;                 /* TLV data */
1035         unsigned long tlv_data_size;    /* TLV data size */
1036         void *priv_data;                /* private data (like strings for enumerated type) */
1037 };
1038
1039 static int snd_ctl_elem_user_info(struct snd_kcontrol *kcontrol,
1040                                   struct snd_ctl_elem_info *uinfo)
1041 {
1042         struct user_element *ue = kcontrol->private_data;
1043         unsigned int offset;
1044
1045         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1046         *uinfo = ue->info;
1047         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1048
1049         return 0;
1050 }
1051
1052 static int snd_ctl_elem_user_enum_info(struct snd_kcontrol *kcontrol,
1053                                        struct snd_ctl_elem_info *uinfo)
1054 {
1055         struct user_element *ue = kcontrol->private_data;
1056         const char *names;
1057         unsigned int item;
1058         unsigned int offset;
1059
1060         item = uinfo->value.enumerated.item;
1061
1062         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1063         *uinfo = ue->info;
1064         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1065
1066         item = min(item, uinfo->value.enumerated.items - 1);
1067         uinfo->value.enumerated.item = item;
1068
1069         names = ue->priv_data;
1070         for (; item > 0; --item)
1071                 names += strlen(names) + 1;
1072         strcpy(uinfo->value.enumerated.name, names);
1073
1074         return 0;
1075 }
1076
1077 static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
1078                                  struct snd_ctl_elem_value *ucontrol)
1079 {
1080         struct user_element *ue = kcontrol->private_data;
1081         unsigned int size = ue->elem_data_size;
1082         char *src = ue->elem_data +
1083                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1084
1085         mutex_lock(&ue->card->user_ctl_lock);
1086         memcpy(&ucontrol->value, src, size);
1087         mutex_unlock(&ue->card->user_ctl_lock);
1088         return 0;
1089 }
1090
1091 static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
1092                                  struct snd_ctl_elem_value *ucontrol)
1093 {
1094         int change;
1095         struct user_element *ue = kcontrol->private_data;
1096         unsigned int size = ue->elem_data_size;
1097         char *dst = ue->elem_data +
1098                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1099
1100         mutex_lock(&ue->card->user_ctl_lock);
1101         change = memcmp(&ucontrol->value, dst, size) != 0;
1102         if (change)
1103                 memcpy(dst, &ucontrol->value, size);
1104         mutex_unlock(&ue->card->user_ctl_lock);
1105         return change;
1106 }
1107
1108 static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol,
1109                                  int op_flag,
1110                                  unsigned int size,
1111                                  unsigned int __user *tlv)
1112 {
1113         struct user_element *ue = kcontrol->private_data;
1114         int change = 0;
1115         void *new_data;
1116
1117         if (op_flag == SNDRV_CTL_TLV_OP_WRITE) {
1118                 if (size > 1024 * 128)  /* sane value */
1119                         return -EINVAL;
1120
1121                 new_data = memdup_user(tlv, size);
1122                 if (IS_ERR(new_data))
1123                         return PTR_ERR(new_data);
1124                 mutex_lock(&ue->card->user_ctl_lock);
1125                 change = ue->tlv_data_size != size;
1126                 if (!change)
1127                         change = memcmp(ue->tlv_data, new_data, size);
1128                 kfree(ue->tlv_data);
1129                 ue->tlv_data = new_data;
1130                 ue->tlv_data_size = size;
1131                 mutex_unlock(&ue->card->user_ctl_lock);
1132         } else {
1133                 int ret = 0;
1134
1135                 mutex_lock(&ue->card->user_ctl_lock);
1136                 if (!ue->tlv_data_size || !ue->tlv_data) {
1137                         ret = -ENXIO;
1138                         goto err_unlock;
1139                 }
1140                 if (size < ue->tlv_data_size) {
1141                         ret = -ENOSPC;
1142                         goto err_unlock;
1143                 }
1144                 if (copy_to_user(tlv, ue->tlv_data, ue->tlv_data_size))
1145                         ret = -EFAULT;
1146 err_unlock:
1147                 mutex_unlock(&ue->card->user_ctl_lock);
1148                 if (ret)
1149                         return ret;
1150         }
1151         return change;
1152 }
1153
1154 static int snd_ctl_elem_init_enum_names(struct user_element *ue)
1155 {
1156         char *names, *p;
1157         size_t buf_len, name_len;
1158         unsigned int i;
1159         const uintptr_t user_ptrval = ue->info.value.enumerated.names_ptr;
1160
1161         if (ue->info.value.enumerated.names_length > 64 * 1024)
1162                 return -EINVAL;
1163
1164         names = memdup_user((const void __user *)user_ptrval,
1165                 ue->info.value.enumerated.names_length);
1166         if (IS_ERR(names))
1167                 return PTR_ERR(names);
1168
1169         /* check that there are enough valid names */
1170         buf_len = ue->info.value.enumerated.names_length;
1171         p = names;
1172         for (i = 0; i < ue->info.value.enumerated.items; ++i) {
1173                 name_len = strnlen(p, buf_len);
1174                 if (name_len == 0 || name_len >= 64 || name_len == buf_len) {
1175                         kfree(names);
1176                         return -EINVAL;
1177                 }
1178                 p += name_len + 1;
1179                 buf_len -= name_len + 1;
1180         }
1181
1182         ue->priv_data = names;
1183         ue->info.value.enumerated.names_ptr = 0;
1184
1185         return 0;
1186 }
1187
1188 static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)
1189 {
1190         struct user_element *ue = kcontrol->private_data;
1191
1192         kfree(ue->tlv_data);
1193         kfree(ue->priv_data);
1194         kfree(ue);
1195 }
1196
1197 static int snd_ctl_elem_add(struct snd_ctl_file *file,
1198                             struct snd_ctl_elem_info *info, int replace)
1199 {
1200         /* The capacity of struct snd_ctl_elem_value.value.*/
1201         static const unsigned int value_sizes[] = {
1202                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = sizeof(long),
1203                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = sizeof(long),
1204                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = sizeof(unsigned int),
1205                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = sizeof(unsigned char),
1206                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = sizeof(struct snd_aes_iec958),
1207                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = sizeof(long long),
1208         };
1209         static const unsigned int max_value_counts[] = {
1210                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = 128,
1211                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = 128,
1212                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = 128,
1213                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = 512,
1214                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = 1,
1215                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = 64,
1216         };
1217         struct snd_card *card = file->card;
1218         struct snd_kcontrol *kctl;
1219         unsigned int count;
1220         unsigned int access;
1221         long private_size;
1222         struct user_element *ue;
1223         unsigned int offset;
1224         int err;
1225
1226         if (!*info->id.name)
1227                 return -EINVAL;
1228         if (strnlen(info->id.name, sizeof(info->id.name)) >= sizeof(info->id.name))
1229                 return -EINVAL;
1230
1231         /* Delete a control to replace them if needed. */
1232         if (replace) {
1233                 info->id.numid = 0;
1234                 err = snd_ctl_remove_user_ctl(file, &info->id);
1235                 if (err)
1236                         return err;
1237         }
1238
1239         /*
1240          * The number of userspace controls are counted control by control,
1241          * not element by element.
1242          */
1243         if (card->user_ctl_count + 1 > MAX_USER_CONTROLS)
1244                 return -ENOMEM;
1245
1246         /* Check the number of elements for this userspace control. */
1247         count = info->owner;
1248         if (count == 0)
1249                 count = 1;
1250
1251         /* Arrange access permissions if needed. */
1252         access = info->access;
1253         if (access == 0)
1254                 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
1255         access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
1256                    SNDRV_CTL_ELEM_ACCESS_INACTIVE |
1257                    SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE);
1258         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE)
1259                 access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
1260         access |= SNDRV_CTL_ELEM_ACCESS_USER;
1261
1262         /*
1263          * Check information and calculate the size of data specific to
1264          * this userspace control.
1265          */
1266         if (info->type < SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
1267             info->type > SNDRV_CTL_ELEM_TYPE_INTEGER64)
1268                 return -EINVAL;
1269         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED &&
1270             info->value.enumerated.items == 0)
1271                 return -EINVAL;
1272         if (info->count < 1 ||
1273             info->count > max_value_counts[info->type])
1274                 return -EINVAL;
1275         private_size = value_sizes[info->type] * info->count;
1276
1277         /*
1278          * Keep memory object for this userspace control. After passing this
1279          * code block, the instance should be freed by snd_ctl_free_one().
1280          *
1281          * Note that these elements in this control are locked.
1282          */
1283         err = snd_ctl_new(&kctl, count, access, file);
1284         if (err < 0)
1285                 return err;
1286         memcpy(&kctl->id, &info->id, sizeof(kctl->id));
1287         kctl->private_data = kzalloc(sizeof(struct user_element) + private_size * count,
1288                                      GFP_KERNEL);
1289         if (kctl->private_data == NULL) {
1290                 kfree(kctl);
1291                 return -ENOMEM;
1292         }
1293         kctl->private_free = snd_ctl_elem_user_free;
1294
1295         /* Set private data for this userspace control. */
1296         ue = (struct user_element *)kctl->private_data;
1297         ue->card = card;
1298         ue->info = *info;
1299         ue->info.access = 0;
1300         ue->elem_data = (char *)ue + sizeof(*ue);
1301         ue->elem_data_size = private_size;
1302         if (ue->info.type == SNDRV_CTL_ELEM_TYPE_ENUMERATED) {
1303                 err = snd_ctl_elem_init_enum_names(ue);
1304                 if (err < 0) {
1305                         snd_ctl_free_one(kctl);
1306                         return err;
1307                 }
1308         }
1309
1310         /* Set callback functions. */
1311         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
1312                 kctl->info = snd_ctl_elem_user_enum_info;
1313         else
1314                 kctl->info = snd_ctl_elem_user_info;
1315         if (access & SNDRV_CTL_ELEM_ACCESS_READ)
1316                 kctl->get = snd_ctl_elem_user_get;
1317         if (access & SNDRV_CTL_ELEM_ACCESS_WRITE)
1318                 kctl->put = snd_ctl_elem_user_put;
1319         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE)
1320                 kctl->tlv.c = snd_ctl_elem_user_tlv;
1321
1322         /* This function manage to free the instance on failure. */
1323         err = snd_ctl_add(card, kctl);
1324         if (err < 0)
1325                 return err;
1326         offset = snd_ctl_get_ioff(kctl, &info->id);
1327         snd_ctl_build_ioff(&info->id, kctl, offset);
1328         /*
1329          * Here we cannot fill any field for the number of elements added by
1330          * this operation because there're no specific fields. The usage of
1331          * 'owner' field for this purpose may cause any bugs to userspace
1332          * applications because the field originally means PID of a process
1333          * which locks the element.
1334          */
1335
1336         down_write(&card->controls_rwsem);
1337         card->user_ctl_count++;
1338         up_write(&card->controls_rwsem);
1339
1340         return 0;
1341 }
1342
1343 static int snd_ctl_elem_add_user(struct snd_ctl_file *file,
1344                                  struct snd_ctl_elem_info __user *_info, int replace)
1345 {
1346         struct snd_ctl_elem_info info;
1347         int err;
1348
1349         if (copy_from_user(&info, _info, sizeof(info)))
1350                 return -EFAULT;
1351         err = snd_ctl_elem_add(file, &info, replace);
1352         if (err < 0)
1353                 return err;
1354         if (copy_to_user(_info, &info, sizeof(info))) {
1355                 snd_ctl_remove_user_ctl(file, &info.id);
1356                 return -EFAULT;
1357         }
1358
1359         return 0;
1360 }
1361
1362 static int snd_ctl_elem_remove(struct snd_ctl_file *file,
1363                                struct snd_ctl_elem_id __user *_id)
1364 {
1365         struct snd_ctl_elem_id id;
1366
1367         if (copy_from_user(&id, _id, sizeof(id)))
1368                 return -EFAULT;
1369         return snd_ctl_remove_user_ctl(file, &id);
1370 }
1371
1372 static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
1373 {
1374         int subscribe;
1375         if (get_user(subscribe, ptr))
1376                 return -EFAULT;
1377         if (subscribe < 0) {
1378                 subscribe = file->subscribed;
1379                 if (put_user(subscribe, ptr))
1380                         return -EFAULT;
1381                 return 0;
1382         }
1383         if (subscribe) {
1384                 file->subscribed = 1;
1385                 return 0;
1386         } else if (file->subscribed) {
1387                 snd_ctl_empty_read_queue(file);
1388                 file->subscribed = 0;
1389         }
1390         return 0;
1391 }
1392
1393 static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
1394                              struct snd_ctl_tlv __user *_tlv,
1395                              int op_flag)
1396 {
1397         struct snd_card *card = file->card;
1398         struct snd_ctl_tlv tlv;
1399         struct snd_kcontrol *kctl;
1400         struct snd_kcontrol_volatile *vd;
1401         unsigned int len;
1402         int err = 0;
1403
1404         if (copy_from_user(&tlv, _tlv, sizeof(tlv)))
1405                 return -EFAULT;
1406         if (tlv.length < sizeof(unsigned int) * 2)
1407                 return -EINVAL;
1408         down_read(&card->controls_rwsem);
1409         kctl = snd_ctl_find_numid(card, tlv.numid);
1410         if (kctl == NULL) {
1411                 err = -ENOENT;
1412                 goto __kctl_end;
1413         }
1414         if (kctl->tlv.p == NULL) {
1415                 err = -ENXIO;
1416                 goto __kctl_end;
1417         }
1418         vd = &kctl->vd[tlv.numid - kctl->id.numid];
1419         if ((op_flag == SNDRV_CTL_TLV_OP_READ &&
1420              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ) == 0) ||
1421             (op_flag == SNDRV_CTL_TLV_OP_WRITE &&
1422              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE) == 0) ||
1423             (op_flag == SNDRV_CTL_TLV_OP_CMD &&
1424              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND) == 0)) {
1425                 err = -ENXIO;
1426                 goto __kctl_end;
1427         }
1428         if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
1429                 if (vd->owner != NULL && vd->owner != file) {
1430                         err = -EPERM;
1431                         goto __kctl_end;
1432                 }
1433                 err = kctl->tlv.c(kctl, op_flag, tlv.length, _tlv->tlv);
1434                 if (err > 0) {
1435                         struct snd_ctl_elem_id id = kctl->id;
1436                         up_read(&card->controls_rwsem);
1437                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_TLV, &id);
1438                         return 0;
1439                 }
1440         } else {
1441                 if (op_flag != SNDRV_CTL_TLV_OP_READ) {
1442                         err = -ENXIO;
1443                         goto __kctl_end;
1444                 }
1445                 len = kctl->tlv.p[1] + 2 * sizeof(unsigned int);
1446                 if (tlv.length < len) {
1447                         err = -ENOMEM;
1448                         goto __kctl_end;
1449                 }
1450                 if (copy_to_user(_tlv->tlv, kctl->tlv.p, len))
1451                         err = -EFAULT;
1452         }
1453       __kctl_end:
1454         up_read(&card->controls_rwsem);
1455         return err;
1456 }
1457
1458 static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1459 {
1460         struct snd_ctl_file *ctl;
1461         struct snd_card *card;
1462         struct snd_kctl_ioctl *p;
1463         void __user *argp = (void __user *)arg;
1464         int __user *ip = argp;
1465         int err;
1466
1467         ctl = file->private_data;
1468         card = ctl->card;
1469         if (snd_BUG_ON(!card))
1470                 return -ENXIO;
1471         switch (cmd) {
1472         case SNDRV_CTL_IOCTL_PVERSION:
1473                 return put_user(SNDRV_CTL_VERSION, ip) ? -EFAULT : 0;
1474         case SNDRV_CTL_IOCTL_CARD_INFO:
1475                 return snd_ctl_card_info(card, ctl, cmd, argp);
1476         case SNDRV_CTL_IOCTL_ELEM_LIST:
1477                 return snd_ctl_elem_list(card, argp);
1478         case SNDRV_CTL_IOCTL_ELEM_INFO:
1479                 return snd_ctl_elem_info_user(ctl, argp);
1480         case SNDRV_CTL_IOCTL_ELEM_READ:
1481                 return snd_ctl_elem_read_user(card, argp);
1482         case SNDRV_CTL_IOCTL_ELEM_WRITE:
1483                 return snd_ctl_elem_write_user(ctl, argp);
1484         case SNDRV_CTL_IOCTL_ELEM_LOCK:
1485                 return snd_ctl_elem_lock(ctl, argp);
1486         case SNDRV_CTL_IOCTL_ELEM_UNLOCK:
1487                 return snd_ctl_elem_unlock(ctl, argp);
1488         case SNDRV_CTL_IOCTL_ELEM_ADD:
1489                 return snd_ctl_elem_add_user(ctl, argp, 0);
1490         case SNDRV_CTL_IOCTL_ELEM_REPLACE:
1491                 return snd_ctl_elem_add_user(ctl, argp, 1);
1492         case SNDRV_CTL_IOCTL_ELEM_REMOVE:
1493                 return snd_ctl_elem_remove(ctl, argp);
1494         case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
1495                 return snd_ctl_subscribe_events(ctl, ip);
1496         case SNDRV_CTL_IOCTL_TLV_READ:
1497                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_READ);
1498         case SNDRV_CTL_IOCTL_TLV_WRITE:
1499                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_WRITE);
1500         case SNDRV_CTL_IOCTL_TLV_COMMAND:
1501                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_CMD);
1502         case SNDRV_CTL_IOCTL_POWER:
1503                 return -ENOPROTOOPT;
1504         case SNDRV_CTL_IOCTL_POWER_STATE:
1505 #ifdef CONFIG_PM
1506                 return put_user(card->power_state, ip) ? -EFAULT : 0;
1507 #else
1508                 return put_user(SNDRV_CTL_POWER_D0, ip) ? -EFAULT : 0;
1509 #endif
1510         }
1511         down_read(&snd_ioctl_rwsem);
1512         list_for_each_entry(p, &snd_control_ioctls, list) {
1513                 err = p->fioctl(card, ctl, cmd, arg);
1514                 if (err != -ENOIOCTLCMD) {
1515                         up_read(&snd_ioctl_rwsem);
1516                         return err;
1517                 }
1518         }
1519         up_read(&snd_ioctl_rwsem);
1520         dev_dbg(card->dev, "unknown ioctl = 0x%x\n", cmd);
1521         return -ENOTTY;
1522 }
1523
1524 static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
1525                             size_t count, loff_t * offset)
1526 {
1527         struct snd_ctl_file *ctl;
1528         int err = 0;
1529         ssize_t result = 0;
1530
1531         ctl = file->private_data;
1532         if (snd_BUG_ON(!ctl || !ctl->card))
1533                 return -ENXIO;
1534         if (!ctl->subscribed)
1535                 return -EBADFD;
1536         if (count < sizeof(struct snd_ctl_event))
1537                 return -EINVAL;
1538         spin_lock_irq(&ctl->read_lock);
1539         while (count >= sizeof(struct snd_ctl_event)) {
1540                 struct snd_ctl_event ev;
1541                 struct snd_kctl_event *kev;
1542                 while (list_empty(&ctl->events)) {
1543                         wait_queue_t wait;
1544                         if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
1545                                 err = -EAGAIN;
1546                                 goto __end_lock;
1547                         }
1548                         init_waitqueue_entry(&wait, current);
1549                         add_wait_queue(&ctl->change_sleep, &wait);
1550                         set_current_state(TASK_INTERRUPTIBLE);
1551                         spin_unlock_irq(&ctl->read_lock);
1552                         schedule();
1553                         remove_wait_queue(&ctl->change_sleep, &wait);
1554                         if (ctl->card->shutdown)
1555                                 return -ENODEV;
1556                         if (signal_pending(current))
1557                                 return -ERESTARTSYS;
1558                         spin_lock_irq(&ctl->read_lock);
1559                 }
1560                 kev = snd_kctl_event(ctl->events.next);
1561                 ev.type = SNDRV_CTL_EVENT_ELEM;
1562                 ev.data.elem.mask = kev->mask;
1563                 ev.data.elem.id = kev->id;
1564                 list_del(&kev->list);
1565                 spin_unlock_irq(&ctl->read_lock);
1566                 kfree(kev);
1567                 if (copy_to_user(buffer, &ev, sizeof(struct snd_ctl_event))) {
1568                         err = -EFAULT;
1569                         goto __end;
1570                 }
1571                 spin_lock_irq(&ctl->read_lock);
1572                 buffer += sizeof(struct snd_ctl_event);
1573                 count -= sizeof(struct snd_ctl_event);
1574                 result += sizeof(struct snd_ctl_event);
1575         }
1576       __end_lock:
1577         spin_unlock_irq(&ctl->read_lock);
1578       __end:
1579         return result > 0 ? result : err;
1580 }
1581
1582 static unsigned int snd_ctl_poll(struct file *file, poll_table * wait)
1583 {
1584         unsigned int mask;
1585         struct snd_ctl_file *ctl;
1586
1587         ctl = file->private_data;
1588         if (!ctl->subscribed)
1589                 return 0;
1590         poll_wait(file, &ctl->change_sleep, wait);
1591
1592         mask = 0;
1593         if (!list_empty(&ctl->events))
1594                 mask |= POLLIN | POLLRDNORM;
1595
1596         return mask;
1597 }
1598
1599 /*
1600  * register the device-specific control-ioctls.
1601  * called from each device manager like pcm.c, hwdep.c, etc.
1602  */
1603 static int _snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn, struct list_head *lists)
1604 {
1605         struct snd_kctl_ioctl *pn;
1606
1607         pn = kzalloc(sizeof(struct snd_kctl_ioctl), GFP_KERNEL);
1608         if (pn == NULL)
1609                 return -ENOMEM;
1610         pn->fioctl = fcn;
1611         down_write(&snd_ioctl_rwsem);
1612         list_add_tail(&pn->list, lists);
1613         up_write(&snd_ioctl_rwsem);
1614         return 0;
1615 }
1616
1617 /**
1618  * snd_ctl_register_ioctl - register the device-specific control-ioctls
1619  * @fcn: ioctl callback function
1620  *
1621  * called from each device manager like pcm.c, hwdep.c, etc.
1622  */
1623 int snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn)
1624 {
1625         return _snd_ctl_register_ioctl(fcn, &snd_control_ioctls);
1626 }
1627 EXPORT_SYMBOL(snd_ctl_register_ioctl);
1628
1629 #ifdef CONFIG_COMPAT
1630 /**
1631  * snd_ctl_register_ioctl_compat - register the device-specific 32bit compat
1632  * control-ioctls
1633  * @fcn: ioctl callback function
1634  */
1635 int snd_ctl_register_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1636 {
1637         return _snd_ctl_register_ioctl(fcn, &snd_control_compat_ioctls);
1638 }
1639 EXPORT_SYMBOL(snd_ctl_register_ioctl_compat);
1640 #endif
1641
1642 /*
1643  * de-register the device-specific control-ioctls.
1644  */
1645 static int _snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn,
1646                                      struct list_head *lists)
1647 {
1648         struct snd_kctl_ioctl *p;
1649
1650         if (snd_BUG_ON(!fcn))
1651                 return -EINVAL;
1652         down_write(&snd_ioctl_rwsem);
1653         list_for_each_entry(p, lists, list) {
1654                 if (p->fioctl == fcn) {
1655                         list_del(&p->list);
1656                         up_write(&snd_ioctl_rwsem);
1657                         kfree(p);
1658                         return 0;
1659                 }
1660         }
1661         up_write(&snd_ioctl_rwsem);
1662         snd_BUG();
1663         return -EINVAL;
1664 }
1665
1666 /**
1667  * snd_ctl_unregister_ioctl - de-register the device-specific control-ioctls
1668  * @fcn: ioctl callback function to unregister
1669  */
1670 int snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn)
1671 {
1672         return _snd_ctl_unregister_ioctl(fcn, &snd_control_ioctls);
1673 }
1674 EXPORT_SYMBOL(snd_ctl_unregister_ioctl);
1675
1676 #ifdef CONFIG_COMPAT
1677 /**
1678  * snd_ctl_unregister_ioctl - de-register the device-specific compat 32bit
1679  * control-ioctls
1680  * @fcn: ioctl callback function to unregister
1681  */
1682 int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1683 {
1684         return _snd_ctl_unregister_ioctl(fcn, &snd_control_compat_ioctls);
1685 }
1686 EXPORT_SYMBOL(snd_ctl_unregister_ioctl_compat);
1687 #endif
1688
1689 static int snd_ctl_fasync(int fd, struct file * file, int on)
1690 {
1691         struct snd_ctl_file *ctl;
1692
1693         ctl = file->private_data;
1694         return fasync_helper(fd, file, on, &ctl->fasync);
1695 }
1696
1697 /* return the preferred subdevice number if already assigned;
1698  * otherwise return -1
1699  */
1700 int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type)
1701 {
1702         struct snd_ctl_file *kctl;
1703         int subdevice = -1;
1704
1705         read_lock(&card->ctl_files_rwlock);
1706         list_for_each_entry(kctl, &card->ctl_files, list) {
1707                 if (kctl->pid == task_pid(current)) {
1708                         subdevice = kctl->preferred_subdevice[type];
1709                         if (subdevice != -1)
1710                                 break;
1711                 }
1712         }
1713         read_unlock(&card->ctl_files_rwlock);
1714         return subdevice;
1715 }
1716 EXPORT_SYMBOL_GPL(snd_ctl_get_preferred_subdevice);
1717
1718 /*
1719  * ioctl32 compat
1720  */
1721 #ifdef CONFIG_COMPAT
1722 #include "control_compat.c"
1723 #else
1724 #define snd_ctl_ioctl_compat    NULL
1725 #endif
1726
1727 /*
1728  *  INIT PART
1729  */
1730
1731 static const struct file_operations snd_ctl_f_ops =
1732 {
1733         .owner =        THIS_MODULE,
1734         .read =         snd_ctl_read,
1735         .open =         snd_ctl_open,
1736         .release =      snd_ctl_release,
1737         .llseek =       no_llseek,
1738         .poll =         snd_ctl_poll,
1739         .unlocked_ioctl =       snd_ctl_ioctl,
1740         .compat_ioctl = snd_ctl_ioctl_compat,
1741         .fasync =       snd_ctl_fasync,
1742 };
1743
1744 /*
1745  * registration of the control device
1746  */
1747 static int snd_ctl_dev_register(struct snd_device *device)
1748 {
1749         struct snd_card *card = device->device_data;
1750
1751         return snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
1752                                    &snd_ctl_f_ops, card, &card->ctl_dev);
1753 }
1754
1755 /*
1756  * disconnection of the control device
1757  */
1758 static int snd_ctl_dev_disconnect(struct snd_device *device)
1759 {
1760         struct snd_card *card = device->device_data;
1761         struct snd_ctl_file *ctl;
1762
1763         read_lock(&card->ctl_files_rwlock);
1764         list_for_each_entry(ctl, &card->ctl_files, list) {
1765                 wake_up(&ctl->change_sleep);
1766                 kill_fasync(&ctl->fasync, SIGIO, POLL_ERR);
1767         }
1768         read_unlock(&card->ctl_files_rwlock);
1769
1770         return snd_unregister_device(&card->ctl_dev);
1771 }
1772
1773 /*
1774  * free all controls
1775  */
1776 static int snd_ctl_dev_free(struct snd_device *device)
1777 {
1778         struct snd_card *card = device->device_data;
1779         struct snd_kcontrol *control;
1780
1781         down_write(&card->controls_rwsem);
1782         while (!list_empty(&card->controls)) {
1783                 control = snd_kcontrol(card->controls.next);
1784                 snd_ctl_remove(card, control);
1785         }
1786         up_write(&card->controls_rwsem);
1787         put_device(&card->ctl_dev);
1788         return 0;
1789 }
1790
1791 /*
1792  * create control core:
1793  * called from init.c
1794  */
1795 int snd_ctl_create(struct snd_card *card)
1796 {
1797         static struct snd_device_ops ops = {
1798                 .dev_free = snd_ctl_dev_free,
1799                 .dev_register = snd_ctl_dev_register,
1800                 .dev_disconnect = snd_ctl_dev_disconnect,
1801         };
1802         int err;
1803
1804         if (snd_BUG_ON(!card))
1805                 return -ENXIO;
1806         if (snd_BUG_ON(card->number < 0 || card->number >= SNDRV_CARDS))
1807                 return -ENXIO;
1808
1809         snd_device_initialize(&card->ctl_dev, card);
1810         dev_set_name(&card->ctl_dev, "controlC%d", card->number);
1811
1812         err = snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
1813         if (err < 0)
1814                 put_device(&card->ctl_dev);
1815         return err;
1816 }
1817
1818 /*
1819  * Frequently used control callbacks/helpers
1820  */
1821
1822 /**
1823  * snd_ctl_boolean_mono_info - Helper function for a standard boolean info
1824  * callback with a mono channel
1825  * @kcontrol: the kcontrol instance
1826  * @uinfo: info to store
1827  *
1828  * This is a function that can be used as info callback for a standard
1829  * boolean control with a single mono channel.
1830  */
1831 int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
1832                               struct snd_ctl_elem_info *uinfo)
1833 {
1834         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1835         uinfo->count = 1;
1836         uinfo->value.integer.min = 0;
1837         uinfo->value.integer.max = 1;
1838         return 0;
1839 }
1840 EXPORT_SYMBOL(snd_ctl_boolean_mono_info);
1841
1842 /**
1843  * snd_ctl_boolean_stereo_info - Helper function for a standard boolean info
1844  * callback with stereo two channels
1845  * @kcontrol: the kcontrol instance
1846  * @uinfo: info to store
1847  *
1848  * This is a function that can be used as info callback for a standard
1849  * boolean control with stereo two channels.
1850  */
1851 int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
1852                                 struct snd_ctl_elem_info *uinfo)
1853 {
1854         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1855         uinfo->count = 2;
1856         uinfo->value.integer.min = 0;
1857         uinfo->value.integer.max = 1;
1858         return 0;
1859 }
1860 EXPORT_SYMBOL(snd_ctl_boolean_stereo_info);
1861
1862 /**
1863  * snd_ctl_enum_info - fills the info structure for an enumerated control
1864  * @info: the structure to be filled
1865  * @channels: the number of the control's channels; often one
1866  * @items: the number of control values; also the size of @names
1867  * @names: an array containing the names of all control values
1868  *
1869  * Sets all required fields in @info to their appropriate values.
1870  * If the control's accessibility is not the default (readable and writable),
1871  * the caller has to fill @info->access.
1872  *
1873  * Return: Zero.
1874  */
1875 int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
1876                       unsigned int items, const char *const names[])
1877 {
1878         info->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
1879         info->count = channels;
1880         info->value.enumerated.items = items;
1881         if (!items)
1882                 return 0;
1883         if (info->value.enumerated.item >= items)
1884                 info->value.enumerated.item = items - 1;
1885         WARN(strlen(names[info->value.enumerated.item]) >= sizeof(info->value.enumerated.name),
1886              "ALSA: too long item name '%s'\n",
1887              names[info->value.enumerated.item]);
1888         strlcpy(info->value.enumerated.name,
1889                 names[info->value.enumerated.item],
1890                 sizeof(info->value.enumerated.name));
1891         return 0;
1892 }
1893 EXPORT_SYMBOL(snd_ctl_enum_info);