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 bool validate_element_member_dimension(struct snd_ctl_elem_info *info)
 818 {
 819         unsigned int members;
 820         unsigned int i;
 821
 822         if (info->dimen.d[0] == 0)
 823                 return true;
 824
 825         members = 1;
 826         for (i = 0; i < ARRAY_SIZE(info->dimen.d); ++i) {
 827                 if (info->dimen.d[i] == 0)
 828                         break;
 829                 members *= info->dimen.d[i];
 830
 831                 /*
 832                  * info->count should be validated in advance, to guarantee
 833                  * calculation soundness.
 834                  */
 835                 if (members > info->count)
 836                         return false;
 837         }
 838
 839         for (++i; i < ARRAY_SIZE(info->dimen.d); ++i) {
 840                 if (info->dimen.d[i] > 0)
 841                         return false;
 842         }
 843
 844         return members == info->count;
 845 }
 846
 847 static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
 848                              struct snd_ctl_elem_info *info)
 849 {
 850         struct snd_card *card = ctl->card;
 851         struct snd_kcontrol *kctl;
 852         struct snd_kcontrol_volatile *vd;
 853         unsigned int index_offset;
 854         int result;
 855
 856         down_read(&card->controls_rwsem);
 857         kctl = snd_ctl_find_id(card, &info->id);
 858         if (kctl == NULL) {
 859                 up_read(&card->controls_rwsem);
 860                 return -ENOENT;
 861         }
 862 #ifdef CONFIG_SND_DEBUG
 863         info->access = 0;
 864 #endif
 865         result = kctl->info(kctl, info);
 866         if (result >= 0) {
 867                 snd_BUG_ON(info->access);
 868                 index_offset = snd_ctl_get_ioff(kctl, &info->id);
 869                 vd = &kctl->vd[index_offset];
 870                 snd_ctl_build_ioff(&info->id, kctl, index_offset);
 871                 info->access = vd->access;
 872                 if (vd->owner) {
 873                         info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
 874                         if (vd->owner == ctl)
 875                                 info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
 876                         info->owner = pid_vnr(vd->owner->pid);
 877                 } else {
 878                         info->owner = -1;
 879                 }
 880         }
 881         up_read(&card->controls_rwsem);
 882         return result;
 883 }
 884
 885 static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
 886                                   struct snd_ctl_elem_info __user *_info)
 887 {
 888         struct snd_ctl_elem_info info;
 889         int result;
 890
 891         if (copy_from_user(&info, _info, sizeof(info)))
 892                 return -EFAULT;
 893         snd_power_lock(ctl->card);
 894         result = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);
 895         if (result >= 0)
 896                 result = snd_ctl_elem_info(ctl, &info);
 897         snd_power_unlock(ctl->card);
 898         if (result >= 0)
 899                 if (copy_to_user(_info, &info, sizeof(info)))
 900                         return -EFAULT;
 901         return result;
 902 }
 903
 904 static int snd_ctl_elem_read(struct snd_card *card,
 905                              struct snd_ctl_elem_value *control)
 906 {
 907         struct snd_kcontrol *kctl;
 908         struct snd_kcontrol_volatile *vd;
 909         unsigned int index_offset;
 910         int result;
 911
 912         down_read(&card->controls_rwsem);
 913         kctl = snd_ctl_find_id(card, &control->id);
 914         if (kctl == NULL) {
 915                 result = -ENOENT;
 916         } else {
 917                 index_offset = snd_ctl_get_ioff(kctl, &control->id);
 918                 vd = &kctl->vd[index_offset];
 919                 if ((vd->access & SNDRV_CTL_ELEM_ACCESS_READ) &&
 920                     kctl->get != NULL) {
 921                         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 922                         result = kctl->get(kctl, control);
 923                 } else
 924                         result = -EPERM;
 925         }
 926         up_read(&card->controls_rwsem);
 927         return result;
 928 }
 929
 930 static int snd_ctl_elem_read_user(struct snd_card *card,
 931                                   struct snd_ctl_elem_value __user *_control)
 932 {
 933         struct snd_ctl_elem_value *control;
 934         int result;
 935
 936         control = memdup_user(_control, sizeof(*control));
 937         if (IS_ERR(control))
 938                 return PTR_ERR(control);
 939
 940         snd_power_lock(card);
 941         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
 942         if (result >= 0)
 943                 result = snd_ctl_elem_read(card, control);
 944         snd_power_unlock(card);
 945         if (result >= 0)
 946                 if (copy_to_user(_control, control, sizeof(*control)))
 947                         result = -EFAULT;
 948         kfree(control);
 949         return result;
 950 }
 951
 952 static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
 953                               struct snd_ctl_elem_value *control)
 954 {
 955         struct snd_kcontrol *kctl;
 956         struct snd_kcontrol_volatile *vd;
 957         unsigned int index_offset;
 958         int result;
 959
 960         down_read(&card->controls_rwsem);
 961         kctl = snd_ctl_find_id(card, &control->id);
 962         if (kctl == NULL) {
 963                 result = -ENOENT;
 964         } else {
 965                 index_offset = snd_ctl_get_ioff(kctl, &control->id);
 966                 vd = &kctl->vd[index_offset];
 967                 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_WRITE) ||
 968                     kctl->put == NULL ||
 969                     (file && vd->owner && vd->owner != file)) {
 970                         result = -EPERM;
 971                 } else {
 972                         snd_ctl_build_ioff(&control->id, kctl, index_offset);
 973                         result = kctl->put(kctl, control);
 974                 }
 975                 if (result > 0) {
 976                         struct snd_ctl_elem_id id = control->id;
 977                         up_read(&card->controls_rwsem);
 978                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, &id);
 979                         return 0;
 980                 }
 981         }
 982         up_read(&card->controls_rwsem);
 983         return result;
 984 }
 985
 986 static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
 987                                    struct snd_ctl_elem_value __user *_control)
 988 {
 989         struct snd_ctl_elem_value *control;
 990         struct snd_card *card;
 991         int result;
 992
 993         control = memdup_user(_control, sizeof(*control));
 994         if (IS_ERR(control))
 995                 return PTR_ERR(control);
 996
 997         card = file->card;
 998         snd_power_lock(card);
 999         result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
1000         if (result >= 0)
1001                 result = snd_ctl_elem_write(card, file, control);
1002         snd_power_unlock(card);
1003         if (result >= 0)
1004                 if (copy_to_user(_control, control, sizeof(*control)))
1005                         result = -EFAULT;
1006         kfree(control);
1007         return result;
1008 }
1009
1010 static int snd_ctl_elem_lock(struct snd_ctl_file *file,
1011                              struct snd_ctl_elem_id __user *_id)
1012 {
1013         struct snd_card *card = file->card;
1014         struct snd_ctl_elem_id id;
1015         struct snd_kcontrol *kctl;
1016         struct snd_kcontrol_volatile *vd;
1017         int result;
1018
1019         if (copy_from_user(&id, _id, sizeof(id)))
1020                 return -EFAULT;
1021         down_write(&card->controls_rwsem);
1022         kctl = snd_ctl_find_id(card, &id);
1023         if (kctl == NULL) {
1024                 result = -ENOENT;
1025         } else {
1026                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1027                 if (vd->owner != NULL)
1028                         result = -EBUSY;
1029                 else {
1030                         vd->owner = file;
1031                         result = 0;
1032                 }
1033         }
1034         up_write(&card->controls_rwsem);
1035         return result;
1036 }
1037
1038 static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
1039                                struct snd_ctl_elem_id __user *_id)
1040 {
1041         struct snd_card *card = file->card;
1042         struct snd_ctl_elem_id id;
1043         struct snd_kcontrol *kctl;
1044         struct snd_kcontrol_volatile *vd;
1045         int result;
1046
1047         if (copy_from_user(&id, _id, sizeof(id)))
1048                 return -EFAULT;
1049         down_write(&card->controls_rwsem);
1050         kctl = snd_ctl_find_id(card, &id);
1051         if (kctl == NULL) {
1052                 result = -ENOENT;
1053         } else {
1054                 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1055                 if (vd->owner == NULL)
1056                         result = -EINVAL;
1057                 else if (vd->owner != file)
1058                         result = -EPERM;
1059                 else {
1060                         vd->owner = NULL;
1061                         result = 0;
1062                 }
1063         }
1064         up_write(&card->controls_rwsem);
1065         return result;
1066 }
1067
1068 struct user_element {
1069         struct snd_ctl_elem_info info;
1070         struct snd_card *card;
1071         char *elem_data;                /* element data */
1072         unsigned long elem_data_size;   /* size of element data in bytes */
1073         void *tlv_data;                 /* TLV data */
1074         unsigned long tlv_data_size;    /* TLV data size */
1075         void *priv_data;                /* private data (like strings for enumerated type) */
1076 };
1077
1078 static int snd_ctl_elem_user_info(struct snd_kcontrol *kcontrol,
1079                                   struct snd_ctl_elem_info *uinfo)
1080 {
1081         struct user_element *ue = kcontrol->private_data;
1082         unsigned int offset;
1083
1084         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1085         *uinfo = ue->info;
1086         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1087
1088         return 0;
1089 }
1090
1091 static int snd_ctl_elem_user_enum_info(struct snd_kcontrol *kcontrol,
1092                                        struct snd_ctl_elem_info *uinfo)
1093 {
1094         struct user_element *ue = kcontrol->private_data;
1095         const char *names;
1096         unsigned int item;
1097         unsigned int offset;
1098
1099         item = uinfo->value.enumerated.item;
1100
1101         offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1102         *uinfo = ue->info;
1103         snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1104
1105         item = min(item, uinfo->value.enumerated.items - 1);
1106         uinfo->value.enumerated.item = item;
1107
1108         names = ue->priv_data;
1109         for (; item > 0; --item)
1110                 names += strlen(names) + 1;
1111         strcpy(uinfo->value.enumerated.name, names);
1112
1113         return 0;
1114 }
1115
1116 static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
1117                                  struct snd_ctl_elem_value *ucontrol)
1118 {
1119         struct user_element *ue = kcontrol->private_data;
1120         unsigned int size = ue->elem_data_size;
1121         char *src = ue->elem_data +
1122                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1123
1124         mutex_lock(&ue->card->user_ctl_lock);
1125         memcpy(&ucontrol->value, src, size);
1126         mutex_unlock(&ue->card->user_ctl_lock);
1127         return 0;
1128 }
1129
1130 static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
1131                                  struct snd_ctl_elem_value *ucontrol)
1132 {
1133         int change;
1134         struct user_element *ue = kcontrol->private_data;
1135         unsigned int size = ue->elem_data_size;
1136         char *dst = ue->elem_data +
1137                         snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1138
1139         mutex_lock(&ue->card->user_ctl_lock);
1140         change = memcmp(&ucontrol->value, dst, size) != 0;
1141         if (change)
1142                 memcpy(dst, &ucontrol->value, size);
1143         mutex_unlock(&ue->card->user_ctl_lock);
1144         return change;
1145 }
1146
1147 static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol,
1148                                  int op_flag,
1149                                  unsigned int size,
1150                                  unsigned int __user *tlv)
1151 {
1152         struct user_element *ue = kcontrol->private_data;
1153         int change = 0;
1154         void *new_data;
1155
1156         if (op_flag == SNDRV_CTL_TLV_OP_WRITE) {
1157                 if (size > 1024 * 128)  /* sane value */
1158                         return -EINVAL;
1159
1160                 new_data = memdup_user(tlv, size);
1161                 if (IS_ERR(new_data))
1162                         return PTR_ERR(new_data);
1163                 mutex_lock(&ue->card->user_ctl_lock);
1164                 change = ue->tlv_data_size != size;
1165                 if (!change)
1166                         change = memcmp(ue->tlv_data, new_data, size) != 0;
1167                 kfree(ue->tlv_data);
1168                 ue->tlv_data = new_data;
1169                 ue->tlv_data_size = size;
1170                 mutex_unlock(&ue->card->user_ctl_lock);
1171         } else {
1172                 int ret = 0;
1173
1174                 mutex_lock(&ue->card->user_ctl_lock);
1175                 if (!ue->tlv_data_size || !ue->tlv_data) {
1176                         ret = -ENXIO;
1177                         goto err_unlock;
1178                 }
1179                 if (size < ue->tlv_data_size) {
1180                         ret = -ENOSPC;
1181                         goto err_unlock;
1182                 }
1183                 if (copy_to_user(tlv, ue->tlv_data, ue->tlv_data_size))
1184                         ret = -EFAULT;
1185 err_unlock:
1186                 mutex_unlock(&ue->card->user_ctl_lock);
1187                 if (ret)
1188                         return ret;
1189         }
1190         return change;
1191 }
1192
1193 static int snd_ctl_elem_init_enum_names(struct user_element *ue)
1194 {
1195         char *names, *p;
1196         size_t buf_len, name_len;
1197         unsigned int i;
1198         const uintptr_t user_ptrval = ue->info.value.enumerated.names_ptr;
1199
1200         if (ue->info.value.enumerated.names_length > 64 * 1024)
1201                 return -EINVAL;
1202
1203         names = memdup_user((const void __user *)user_ptrval,
1204                 ue->info.value.enumerated.names_length);
1205         if (IS_ERR(names))
1206                 return PTR_ERR(names);
1207
1208         /* check that there are enough valid names */
1209         buf_len = ue->info.value.enumerated.names_length;
1210         p = names;
1211         for (i = 0; i < ue->info.value.enumerated.items; ++i) {
1212                 name_len = strnlen(p, buf_len);
1213                 if (name_len == 0 || name_len >= 64 || name_len == buf_len) {
1214                         kfree(names);
1215                         return -EINVAL;
1216                 }
1217                 p += name_len + 1;
1218                 buf_len -= name_len + 1;
1219         }
1220
1221         ue->priv_data = names;
1222         ue->info.value.enumerated.names_ptr = 0;
1223
1224         return 0;
1225 }
1226
1227 static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)
1228 {
1229         struct user_element *ue = kcontrol->private_data;
1230
1231         kfree(ue->tlv_data);
1232         kfree(ue->priv_data);
1233         kfree(ue);
1234 }
1235
1236 static int snd_ctl_elem_add(struct snd_ctl_file *file,
1237                             struct snd_ctl_elem_info *info, int replace)
1238 {
1239         /* The capacity of struct snd_ctl_elem_value.value.*/
1240         static const unsigned int value_sizes[] = {
1241                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = sizeof(long),
1242                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = sizeof(long),
1243                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = sizeof(unsigned int),
1244                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = sizeof(unsigned char),
1245                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = sizeof(struct snd_aes_iec958),
1246                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = sizeof(long long),
1247         };
1248         static const unsigned int max_value_counts[] = {
1249                 [SNDRV_CTL_ELEM_TYPE_BOOLEAN]   = 128,
1250                 [SNDRV_CTL_ELEM_TYPE_INTEGER]   = 128,
1251                 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = 128,
1252                 [SNDRV_CTL_ELEM_TYPE_BYTES]     = 512,
1253                 [SNDRV_CTL_ELEM_TYPE_IEC958]    = 1,
1254                 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = 64,
1255         };
1256         struct snd_card *card = file->card;
1257         struct snd_kcontrol *kctl;
1258         unsigned int count;
1259         unsigned int access;
1260         long private_size;
1261         struct user_element *ue;
1262         unsigned int offset;
1263         int err;
1264
1265         if (!*info->id.name)
1266                 return -EINVAL;
1267         if (strnlen(info->id.name, sizeof(info->id.name)) >= sizeof(info->id.name))
1268                 return -EINVAL;
1269
1270         /* Delete a control to replace them if needed. */
1271         if (replace) {
1272                 info->id.numid = 0;
1273                 err = snd_ctl_remove_user_ctl(file, &info->id);
1274                 if (err)
1275                         return err;
1276         }
1277
1278         /*
1279          * The number of userspace controls are counted control by control,
1280          * not element by element.
1281          */
1282         if (card->user_ctl_count + 1 > MAX_USER_CONTROLS)
1283                 return -ENOMEM;
1284
1285         /* Check the number of elements for this userspace control. */
1286         count = info->owner;
1287         if (count == 0)
1288                 count = 1;
1289
1290         /* Arrange access permissions if needed. */
1291         access = info->access;
1292         if (access == 0)
1293                 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
1294         access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
1295                    SNDRV_CTL_ELEM_ACCESS_INACTIVE |
1296                    SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE);
1297         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE)
1298                 access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
1299         access |= SNDRV_CTL_ELEM_ACCESS_USER;
1300
1301         /*
1302          * Check information and calculate the size of data specific to
1303          * this userspace control.
1304          */
1305         if (info->type < SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
1306             info->type > SNDRV_CTL_ELEM_TYPE_INTEGER64)
1307                 return -EINVAL;
1308         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED &&
1309             info->value.enumerated.items == 0)
1310                 return -EINVAL;
1311         if (info->count < 1 ||
1312             info->count > max_value_counts[info->type])
1313                 return -EINVAL;
1314         if (!validate_element_member_dimension(info))
1315                 return -EINVAL;
1316         private_size = value_sizes[info->type] * info->count;
1317
1318         /*
1319          * Keep memory object for this userspace control. After passing this
1320          * code block, the instance should be freed by snd_ctl_free_one().
1321          *
1322          * Note that these elements in this control are locked.
1323          */
1324         err = snd_ctl_new(&kctl, count, access, file);
1325         if (err < 0)
1326                 return err;
1327         memcpy(&kctl->id, &info->id, sizeof(kctl->id));
1328         kctl->private_data = kzalloc(sizeof(struct user_element) + private_size * count,
1329                                      GFP_KERNEL);
1330         if (kctl->private_data == NULL) {
1331                 kfree(kctl);
1332                 return -ENOMEM;
1333         }
1334         kctl->private_free = snd_ctl_elem_user_free;
1335
1336         /* Set private data for this userspace control. */
1337         ue = (struct user_element *)kctl->private_data;
1338         ue->card = card;
1339         ue->info = *info;
1340         ue->info.access = 0;
1341         ue->elem_data = (char *)ue + sizeof(*ue);
1342         ue->elem_data_size = private_size;
1343         if (ue->info.type == SNDRV_CTL_ELEM_TYPE_ENUMERATED) {
1344                 err = snd_ctl_elem_init_enum_names(ue);
1345                 if (err < 0) {
1346                         snd_ctl_free_one(kctl);
1347                         return err;
1348                 }
1349         }
1350
1351         /* Set callback functions. */
1352         if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
1353                 kctl->info = snd_ctl_elem_user_enum_info;
1354         else
1355                 kctl->info = snd_ctl_elem_user_info;
1356         if (access & SNDRV_CTL_ELEM_ACCESS_READ)
1357                 kctl->get = snd_ctl_elem_user_get;
1358         if (access & SNDRV_CTL_ELEM_ACCESS_WRITE)
1359                 kctl->put = snd_ctl_elem_user_put;
1360         if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE)
1361                 kctl->tlv.c = snd_ctl_elem_user_tlv;
1362
1363         /* This function manage to free the instance on failure. */
1364         down_write(&card->controls_rwsem);
1365         err = __snd_ctl_add(card, kctl);
1366         if (err < 0) {
1367                 snd_ctl_free_one(kctl);
1368                 goto unlock;
1369         }
1370         offset = snd_ctl_get_ioff(kctl, &info->id);
1371         snd_ctl_build_ioff(&info->id, kctl, offset);
1372         /*
1373          * Here we cannot fill any field for the number of elements added by
1374          * this operation because there're no specific fields. The usage of
1375          * 'owner' field for this purpose may cause any bugs to userspace
1376          * applications because the field originally means PID of a process
1377          * which locks the element.
1378          */
1379
1380         card->user_ctl_count++;
1381
1382  unlock:
1383         up_write(&card->controls_rwsem);
1384         return err;
1385 }
1386
1387 static int snd_ctl_elem_add_user(struct snd_ctl_file *file,
1388                                  struct snd_ctl_elem_info __user *_info, int replace)
1389 {
1390         struct snd_ctl_elem_info info;
1391         int err;
1392
1393         if (copy_from_user(&info, _info, sizeof(info)))
1394                 return -EFAULT;
1395         err = snd_ctl_elem_add(file, &info, replace);
1396         if (err < 0)
1397                 return err;
1398         if (copy_to_user(_info, &info, sizeof(info))) {
1399                 snd_ctl_remove_user_ctl(file, &info.id);
1400                 return -EFAULT;
1401         }
1402
1403         return 0;
1404 }
1405
1406 static int snd_ctl_elem_remove(struct snd_ctl_file *file,
1407                                struct snd_ctl_elem_id __user *_id)
1408 {
1409         struct snd_ctl_elem_id id;
1410
1411         if (copy_from_user(&id, _id, sizeof(id)))
1412                 return -EFAULT;
1413         return snd_ctl_remove_user_ctl(file, &id);
1414 }
1415
1416 static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
1417 {
1418         int subscribe;
1419         if (get_user(subscribe, ptr))
1420                 return -EFAULT;
1421         if (subscribe < 0) {
1422                 subscribe = file->subscribed;
1423                 if (put_user(subscribe, ptr))
1424                         return -EFAULT;
1425                 return 0;
1426         }
1427         if (subscribe) {
1428                 file->subscribed = 1;
1429                 return 0;
1430         } else if (file->subscribed) {
1431                 snd_ctl_empty_read_queue(file);
1432                 file->subscribed = 0;
1433         }
1434         return 0;
1435 }
1436
1437 static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
1438                              struct snd_ctl_tlv __user *_tlv,
1439                              int op_flag)
1440 {
1441         struct snd_card *card = file->card;
1442         struct snd_ctl_tlv tlv;
1443         struct snd_kcontrol *kctl;
1444         struct snd_kcontrol_volatile *vd;
1445         unsigned int len;
1446         int err = 0;
1447
1448         if (copy_from_user(&tlv, _tlv, sizeof(tlv)))
1449                 return -EFAULT;
1450         if (tlv.length < sizeof(unsigned int) * 2)
1451                 return -EINVAL;
1452         if (!tlv.numid)
1453                 return -EINVAL;
1454         down_read(&card->controls_rwsem);
1455         kctl = snd_ctl_find_numid(card, tlv.numid);
1456         if (kctl == NULL) {
1457                 err = -ENOENT;
1458                 goto __kctl_end;
1459         }
1460         if (kctl->tlv.p == NULL) {
1461                 err = -ENXIO;
1462                 goto __kctl_end;
1463         }
1464         vd = &kctl->vd[tlv.numid - kctl->id.numid];
1465         if ((op_flag == SNDRV_CTL_TLV_OP_READ &&
1466              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ) == 0) ||
1467             (op_flag == SNDRV_CTL_TLV_OP_WRITE &&
1468              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE) == 0) ||
1469             (op_flag == SNDRV_CTL_TLV_OP_CMD &&
1470              (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND) == 0)) {
1471                 err = -ENXIO;
1472                 goto __kctl_end;
1473         }
1474         if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
1475                 if (vd->owner != NULL && vd->owner != file) {
1476                         err = -EPERM;
1477                         goto __kctl_end;
1478                 }
1479                 err = kctl->tlv.c(kctl, op_flag, tlv.length, _tlv->tlv);
1480                 if (err > 0) {
1481                         struct snd_ctl_elem_id id = kctl->id;
1482                         up_read(&card->controls_rwsem);
1483                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_TLV, &id);
1484                         return 0;
1485                 }
1486         } else {
1487                 if (op_flag != SNDRV_CTL_TLV_OP_READ) {
1488                         err = -ENXIO;
1489                         goto __kctl_end;
1490                 }
1491                 len = kctl->tlv.p[1] + 2 * sizeof(unsigned int);
1492                 if (tlv.length < len) {
1493                         err = -ENOMEM;
1494                         goto __kctl_end;
1495                 }
1496                 if (copy_to_user(_tlv->tlv, kctl->tlv.p, len))
1497                         err = -EFAULT;
1498         }
1499       __kctl_end:
1500         up_read(&card->controls_rwsem);
1501         return err;
1502 }
1503
1504 static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1505 {
1506         struct snd_ctl_file *ctl;
1507         struct snd_card *card;
1508         struct snd_kctl_ioctl *p;
1509         void __user *argp = (void __user *)arg;
1510         int __user *ip = argp;
1511         int err;
1512
1513         ctl = file->private_data;
1514         card = ctl->card;
1515         if (snd_BUG_ON(!card))
1516                 return -ENXIO;
1517         switch (cmd) {
1518         case SNDRV_CTL_IOCTL_PVERSION:
1519                 return put_user(SNDRV_CTL_VERSION, ip) ? -EFAULT : 0;
1520         case SNDRV_CTL_IOCTL_CARD_INFO:
1521                 return snd_ctl_card_info(card, ctl, cmd, argp);
1522         case SNDRV_CTL_IOCTL_ELEM_LIST:
1523                 return snd_ctl_elem_list(card, argp);
1524         case SNDRV_CTL_IOCTL_ELEM_INFO:
1525                 return snd_ctl_elem_info_user(ctl, argp);
1526         case SNDRV_CTL_IOCTL_ELEM_READ:
1527                 return snd_ctl_elem_read_user(card, argp);
1528         case SNDRV_CTL_IOCTL_ELEM_WRITE:
1529                 return snd_ctl_elem_write_user(ctl, argp);
1530         case SNDRV_CTL_IOCTL_ELEM_LOCK:
1531                 return snd_ctl_elem_lock(ctl, argp);
1532         case SNDRV_CTL_IOCTL_ELEM_UNLOCK:
1533                 return snd_ctl_elem_unlock(ctl, argp);
1534         case SNDRV_CTL_IOCTL_ELEM_ADD:
1535                 return snd_ctl_elem_add_user(ctl, argp, 0);
1536         case SNDRV_CTL_IOCTL_ELEM_REPLACE:
1537                 return snd_ctl_elem_add_user(ctl, argp, 1);
1538         case SNDRV_CTL_IOCTL_ELEM_REMOVE:
1539                 return snd_ctl_elem_remove(ctl, argp);
1540         case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
1541                 return snd_ctl_subscribe_events(ctl, ip);
1542         case SNDRV_CTL_IOCTL_TLV_READ:
1543                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_READ);
1544         case SNDRV_CTL_IOCTL_TLV_WRITE:
1545                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_WRITE);
1546         case SNDRV_CTL_IOCTL_TLV_COMMAND:
1547                 return snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_CMD);
1548         case SNDRV_CTL_IOCTL_POWER:
1549                 return -ENOPROTOOPT;
1550         case SNDRV_CTL_IOCTL_POWER_STATE:
1551 #ifdef CONFIG_PM
1552                 return put_user(card->power_state, ip) ? -EFAULT : 0;
1553 #else
1554                 return put_user(SNDRV_CTL_POWER_D0, ip) ? -EFAULT : 0;
1555 #endif
1556         }
1557         down_read(&snd_ioctl_rwsem);
1558         list_for_each_entry(p, &snd_control_ioctls, list) {
1559                 err = p->fioctl(card, ctl, cmd, arg);
1560                 if (err != -ENOIOCTLCMD) {
1561                         up_read(&snd_ioctl_rwsem);
1562                         return err;
1563                 }
1564         }
1565         up_read(&snd_ioctl_rwsem);
1566         dev_dbg(card->dev, "unknown ioctl = 0x%x\n", cmd);
1567         return -ENOTTY;
1568 }
1569
1570 static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
1571                             size_t count, loff_t * offset)
1572 {
1573         struct snd_ctl_file *ctl;
1574         int err = 0;
1575         ssize_t result = 0;
1576
1577         ctl = file->private_data;
1578         if (snd_BUG_ON(!ctl || !ctl->card))
1579                 return -ENXIO;
1580         if (!ctl->subscribed)
1581                 return -EBADFD;
1582         if (count < sizeof(struct snd_ctl_event))
1583                 return -EINVAL;
1584         spin_lock_irq(&ctl->read_lock);
1585         while (count >= sizeof(struct snd_ctl_event)) {
1586                 struct snd_ctl_event ev;
1587                 struct snd_kctl_event *kev;
1588                 while (list_empty(&ctl->events)) {
1589                         wait_queue_t wait;
1590                         if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
1591                                 err = -EAGAIN;
1592                                 goto __end_lock;
1593                         }
1594                         init_waitqueue_entry(&wait, current);
1595                         add_wait_queue(&ctl->change_sleep, &wait);
1596                         set_current_state(TASK_INTERRUPTIBLE);
1597                         spin_unlock_irq(&ctl->read_lock);
1598                         schedule();
1599                         remove_wait_queue(&ctl->change_sleep, &wait);
1600                         if (ctl->card->shutdown)
1601                                 return -ENODEV;
1602                         if (signal_pending(current))
1603                                 return -ERESTARTSYS;
1604                         spin_lock_irq(&ctl->read_lock);
1605                 }
1606                 kev = snd_kctl_event(ctl->events.next);
1607                 ev.type = SNDRV_CTL_EVENT_ELEM;
1608                 ev.data.elem.mask = kev->mask;
1609                 ev.data.elem.id = kev->id;
1610                 list_del(&kev->list);
1611                 spin_unlock_irq(&ctl->read_lock);
1612                 kfree(kev);
1613                 if (copy_to_user(buffer, &ev, sizeof(struct snd_ctl_event))) {
1614                         err = -EFAULT;
1615                         goto __end;
1616                 }
1617                 spin_lock_irq(&ctl->read_lock);
1618                 buffer += sizeof(struct snd_ctl_event);
1619                 count -= sizeof(struct snd_ctl_event);
1620                 result += sizeof(struct snd_ctl_event);
1621         }
1622       __end_lock:
1623         spin_unlock_irq(&ctl->read_lock);
1624       __end:
1625         return result > 0 ? result : err;
1626 }
1627
1628 static unsigned int snd_ctl_poll(struct file *file, poll_table * wait)
1629 {
1630         unsigned int mask;
1631         struct snd_ctl_file *ctl;
1632
1633         ctl = file->private_data;
1634         if (!ctl->subscribed)
1635                 return 0;
1636         poll_wait(file, &ctl->change_sleep, wait);
1637
1638         mask = 0;
1639         if (!list_empty(&ctl->events))
1640                 mask |= POLLIN | POLLRDNORM;
1641
1642         return mask;
1643 }
1644
1645 /*
1646  * register the device-specific control-ioctls.
1647  * called from each device manager like pcm.c, hwdep.c, etc.
1648  */
1649 static int _snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn, struct list_head *lists)
1650 {
1651         struct snd_kctl_ioctl *pn;
1652
1653         pn = kzalloc(sizeof(struct snd_kctl_ioctl), GFP_KERNEL);
1654         if (pn == NULL)
1655                 return -ENOMEM;
1656         pn->fioctl = fcn;
1657         down_write(&snd_ioctl_rwsem);
1658         list_add_tail(&pn->list, lists);
1659         up_write(&snd_ioctl_rwsem);
1660         return 0;
1661 }
1662
1663 /**
1664  * snd_ctl_register_ioctl - register the device-specific control-ioctls
1665  * @fcn: ioctl callback function
1666  *
1667  * called from each device manager like pcm.c, hwdep.c, etc.
1668  */
1669 int snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn)
1670 {
1671         return _snd_ctl_register_ioctl(fcn, &snd_control_ioctls);
1672 }
1673 EXPORT_SYMBOL(snd_ctl_register_ioctl);
1674
1675 #ifdef CONFIG_COMPAT
1676 /**
1677  * snd_ctl_register_ioctl_compat - register the device-specific 32bit compat
1678  * control-ioctls
1679  * @fcn: ioctl callback function
1680  */
1681 int snd_ctl_register_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1682 {
1683         return _snd_ctl_register_ioctl(fcn, &snd_control_compat_ioctls);
1684 }
1685 EXPORT_SYMBOL(snd_ctl_register_ioctl_compat);
1686 #endif
1687
1688 /*
1689  * de-register the device-specific control-ioctls.
1690  */
1691 static int _snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn,
1692                                      struct list_head *lists)
1693 {
1694         struct snd_kctl_ioctl *p;
1695
1696         if (snd_BUG_ON(!fcn))
1697                 return -EINVAL;
1698         down_write(&snd_ioctl_rwsem);
1699         list_for_each_entry(p, lists, list) {
1700                 if (p->fioctl == fcn) {
1701                         list_del(&p->list);
1702                         up_write(&snd_ioctl_rwsem);
1703                         kfree(p);
1704                         return 0;
1705                 }
1706         }
1707         up_write(&snd_ioctl_rwsem);
1708         snd_BUG();
1709         return -EINVAL;
1710 }
1711
1712 /**
1713  * snd_ctl_unregister_ioctl - de-register the device-specific control-ioctls
1714  * @fcn: ioctl callback function to unregister
1715  */
1716 int snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn)
1717 {
1718         return _snd_ctl_unregister_ioctl(fcn, &snd_control_ioctls);
1719 }
1720 EXPORT_SYMBOL(snd_ctl_unregister_ioctl);
1721
1722 #ifdef CONFIG_COMPAT
1723 /**
1724  * snd_ctl_unregister_ioctl - de-register the device-specific compat 32bit
1725  * control-ioctls
1726  * @fcn: ioctl callback function to unregister
1727  */
1728 int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1729 {
1730         return _snd_ctl_unregister_ioctl(fcn, &snd_control_compat_ioctls);
1731 }
1732 EXPORT_SYMBOL(snd_ctl_unregister_ioctl_compat);
1733 #endif
1734
1735 static int snd_ctl_fasync(int fd, struct file * file, int on)
1736 {
1737         struct snd_ctl_file *ctl;
1738
1739         ctl = file->private_data;
1740         return fasync_helper(fd, file, on, &ctl->fasync);
1741 }
1742
1743 /* return the preferred subdevice number if already assigned;
1744  * otherwise return -1
1745  */
1746 int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type)
1747 {
1748         struct snd_ctl_file *kctl;
1749         int subdevice = -1;
1750
1751         read_lock(&card->ctl_files_rwlock);
1752         list_for_each_entry(kctl, &card->ctl_files, list) {
1753                 if (kctl->pid == task_pid(current)) {
1754                         subdevice = kctl->preferred_subdevice[type];
1755                         if (subdevice != -1)
1756                                 break;
1757                 }
1758         }
1759         read_unlock(&card->ctl_files_rwlock);
1760         return subdevice;
1761 }
1762 EXPORT_SYMBOL_GPL(snd_ctl_get_preferred_subdevice);
1763
1764 /*
1765  * ioctl32 compat
1766  */
1767 #ifdef CONFIG_COMPAT
1768 #include "control_compat.c"
1769 #else
1770 #define snd_ctl_ioctl_compat    NULL
1771 #endif
1772
1773 /*
1774  *  INIT PART
1775  */
1776
1777 static const struct file_operations snd_ctl_f_ops =
1778 {
1779         .owner =        THIS_MODULE,
1780         .read =         snd_ctl_read,
1781         .open =         snd_ctl_open,
1782         .release =      snd_ctl_release,
1783         .llseek =       no_llseek,
1784         .poll =         snd_ctl_poll,
1785         .unlocked_ioctl =       snd_ctl_ioctl,
1786         .compat_ioctl = snd_ctl_ioctl_compat,
1787         .fasync =       snd_ctl_fasync,
1788 };
1789
1790 /*
1791  * registration of the control device
1792  */
1793 static int snd_ctl_dev_register(struct snd_device *device)
1794 {
1795         struct snd_card *card = device->device_data;
1796
1797         return snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
1798                                    &snd_ctl_f_ops, card, &card->ctl_dev);
1799 }
1800
1801 /*
1802  * disconnection of the control device
1803  */
1804 static int snd_ctl_dev_disconnect(struct snd_device *device)
1805 {
1806         struct snd_card *card = device->device_data;
1807         struct snd_ctl_file *ctl;
1808
1809         read_lock(&card->ctl_files_rwlock);
1810         list_for_each_entry(ctl, &card->ctl_files, list) {
1811                 wake_up(&ctl->change_sleep);
1812                 kill_fasync(&ctl->fasync, SIGIO, POLL_ERR);
1813         }
1814         read_unlock(&card->ctl_files_rwlock);
1815
1816         return snd_unregister_device(&card->ctl_dev);
1817 }
1818
1819 /*
1820  * free all controls
1821  */
1822 static int snd_ctl_dev_free(struct snd_device *device)
1823 {
1824         struct snd_card *card = device->device_data;
1825         struct snd_kcontrol *control;
1826
1827         down_write(&card->controls_rwsem);
1828         while (!list_empty(&card->controls)) {
1829                 control = snd_kcontrol(card->controls.next);
1830                 snd_ctl_remove(card, control);
1831         }
1832         up_write(&card->controls_rwsem);
1833         put_device(&card->ctl_dev);
1834         return 0;
1835 }
1836
1837 /*
1838  * create control core:
1839  * called from init.c
1840  */
1841 int snd_ctl_create(struct snd_card *card)
1842 {
1843         static struct snd_device_ops ops = {
1844                 .dev_free = snd_ctl_dev_free,
1845                 .dev_register = snd_ctl_dev_register,
1846                 .dev_disconnect = snd_ctl_dev_disconnect,
1847         };
1848         int err;
1849
1850         if (snd_BUG_ON(!card))
1851                 return -ENXIO;
1852         if (snd_BUG_ON(card->number < 0 || card->number >= SNDRV_CARDS))
1853                 return -ENXIO;
1854
1855         snd_device_initialize(&card->ctl_dev, card);
1856         dev_set_name(&card->ctl_dev, "controlC%d", card->number);
1857
1858         err = snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
1859         if (err < 0)
1860                 put_device(&card->ctl_dev);
1861         return err;
1862 }
1863
1864 /*
1865  * Frequently used control callbacks/helpers
1866  */
1867
1868 /**
1869  * snd_ctl_boolean_mono_info - Helper function for a standard boolean info
1870  * callback with a mono channel
1871  * @kcontrol: the kcontrol instance
1872  * @uinfo: info to store
1873  *
1874  * This is a function that can be used as info callback for a standard
1875  * boolean control with a single mono channel.
1876  */
1877 int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
1878                               struct snd_ctl_elem_info *uinfo)
1879 {
1880         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1881         uinfo->count = 1;
1882         uinfo->value.integer.min = 0;
1883         uinfo->value.integer.max = 1;
1884         return 0;
1885 }
1886 EXPORT_SYMBOL(snd_ctl_boolean_mono_info);
1887
1888 /**
1889  * snd_ctl_boolean_stereo_info - Helper function for a standard boolean info
1890  * callback with stereo two channels
1891  * @kcontrol: the kcontrol instance
1892  * @uinfo: info to store
1893  *
1894  * This is a function that can be used as info callback for a standard
1895  * boolean control with stereo two channels.
1896  */
1897 int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
1898                                 struct snd_ctl_elem_info *uinfo)
1899 {
1900         uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1901         uinfo->count = 2;
1902         uinfo->value.integer.min = 0;
1903         uinfo->value.integer.max = 1;
1904         return 0;
1905 }
1906 EXPORT_SYMBOL(snd_ctl_boolean_stereo_info);
1907
1908 /**
1909  * snd_ctl_enum_info - fills the info structure for an enumerated control
1910  * @info: the structure to be filled
1911  * @channels: the number of the control's channels; often one
1912  * @items: the number of control values; also the size of @names
1913  * @names: an array containing the names of all control values
1914  *
1915  * Sets all required fields in @info to their appropriate values.
1916  * If the control's accessibility is not the default (readable and writable),
1917  * the caller has to fill @info->access.
1918  *
1919  * Return: Zero.
1920  */
1921 int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
1922                       unsigned int items, const char *const names[])
1923 {
1924         info->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
1925         info->count = channels;
1926         info->value.enumerated.items = items;
1927         if (!items)
1928                 return 0;
1929         if (info->value.enumerated.item >= items)
1930                 info->value.enumerated.item = items - 1;
1931         WARN(strlen(names[info->value.enumerated.item]) >= sizeof(info->value.enumerated.name),
1932              "ALSA: too long item name '%s'\n",
1933              names[info->value.enumerated.item]);
1934         strlcpy(info->value.enumerated.name,
1935                 names[info->value.enumerated.item],
1936                 sizeof(info->value.enumerated.name));
1937         return 0;
1938 }
1939 EXPORT_SYMBOL(snd_ctl_enum_info);