1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Routines for driver control interface
4 * Copyright (c) by Jaroslav Kysela <perex@perex.cz>
7 #include <linux/threads.h>
8 #include <linux/interrupt.h>
9 #include <linux/module.h>
10 #include <linux/moduleparam.h>
11 #include <linux/slab.h>
12 #include <linux/vmalloc.h>
13 #include <linux/time.h>
15 #include <linux/math64.h>
16 #include <linux/sched/signal.h>
17 #include <sound/core.h>
18 #include <sound/minors.h>
19 #include <sound/info.h>
20 #include <sound/control.h>
22 // Max allocation size for user controls.
23 static int max_user_ctl_alloc_size = 8 * 1024 * 1024;
24 module_param_named(max_user_ctl_alloc_size, max_user_ctl_alloc_size, int, 0444);
25 MODULE_PARM_DESC(max_user_ctl_alloc_size, "Max allocation size for user controls");
27 #define MAX_CONTROL_COUNT 1028
29 struct snd_kctl_ioctl {
30 struct list_head list; /* list of all ioctls */
31 snd_kctl_ioctl_func_t fioctl;
34 static DECLARE_RWSEM(snd_ioctl_rwsem);
35 static DECLARE_RWSEM(snd_ctl_layer_rwsem);
36 static LIST_HEAD(snd_control_ioctls);
38 static LIST_HEAD(snd_control_compat_ioctls);
40 static struct snd_ctl_layer_ops *snd_ctl_layer;
42 static int snd_ctl_remove_locked(struct snd_card *card,
43 struct snd_kcontrol *kcontrol);
45 static int snd_ctl_open(struct inode *inode, struct file *file)
47 struct snd_card *card;
48 struct snd_ctl_file *ctl;
51 err = stream_open(inode, file);
55 card = snd_lookup_minor_data(iminor(inode), SNDRV_DEVICE_TYPE_CONTROL);
60 err = snd_card_file_add(card, file);
65 if (!try_module_get(card->module)) {
69 ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);
74 INIT_LIST_HEAD(&ctl->events);
75 init_waitqueue_head(&ctl->change_sleep);
76 spin_lock_init(&ctl->read_lock);
78 for (i = 0; i < SND_CTL_SUBDEV_ITEMS; i++)
79 ctl->preferred_subdevice[i] = -1;
80 ctl->pid = get_pid(task_pid(current));
81 file->private_data = ctl;
82 scoped_guard(write_lock_irqsave, &card->controls_rwlock)
83 list_add_tail(&ctl->list, &card->ctl_files);
88 module_put(card->module);
90 snd_card_file_remove(card, file);
97 static void snd_ctl_empty_read_queue(struct snd_ctl_file * ctl)
99 struct snd_kctl_event *cread;
101 guard(spinlock_irqsave)(&ctl->read_lock);
102 while (!list_empty(&ctl->events)) {
103 cread = snd_kctl_event(ctl->events.next);
104 list_del(&cread->list);
109 static int snd_ctl_release(struct inode *inode, struct file *file)
111 struct snd_card *card;
112 struct snd_ctl_file *ctl;
113 struct snd_kcontrol *control;
116 ctl = file->private_data;
117 file->private_data = NULL;
120 scoped_guard(write_lock_irqsave, &card->controls_rwlock)
121 list_del(&ctl->list);
123 scoped_guard(rwsem_write, &card->controls_rwsem) {
124 list_for_each_entry(control, &card->controls, list)
125 for (idx = 0; idx < control->count; idx++)
126 if (control->vd[idx].owner == ctl)
127 control->vd[idx].owner = NULL;
130 snd_fasync_free(ctl->fasync);
131 snd_ctl_empty_read_queue(ctl);
134 module_put(card->module);
135 snd_card_file_remove(card, file);
140 * snd_ctl_notify - Send notification to user-space for a control change
141 * @card: the card to send notification
142 * @mask: the event mask, SNDRV_CTL_EVENT_*
143 * @id: the ctl element id to send notification
145 * This function adds an event record with the given id and mask, appends
146 * to the list and wakes up the user-space for notification. This can be
147 * called in the atomic context.
149 void snd_ctl_notify(struct snd_card *card, unsigned int mask,
150 struct snd_ctl_elem_id *id)
152 struct snd_ctl_file *ctl;
153 struct snd_kctl_event *ev;
155 if (snd_BUG_ON(!card || !id))
160 guard(read_lock_irqsave)(&card->controls_rwlock);
161 #if IS_ENABLED(CONFIG_SND_MIXER_OSS)
162 card->mixer_oss_change_count++;
164 list_for_each_entry(ctl, &card->ctl_files, list) {
165 if (!ctl->subscribed)
167 scoped_guard(spinlock, &ctl->read_lock) {
168 list_for_each_entry(ev, &ctl->events, list) {
169 if (ev->id.numid == id->numid) {
174 ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
178 list_add_tail(&ev->list, &ctl->events);
180 dev_err(card->dev, "No memory available to allocate event\n");
183 wake_up(&ctl->change_sleep);
185 snd_kill_fasync(ctl->fasync, SIGIO, POLL_IN);
188 EXPORT_SYMBOL(snd_ctl_notify);
191 * snd_ctl_notify_one - Send notification to user-space for a control change
192 * @card: the card to send notification
193 * @mask: the event mask, SNDRV_CTL_EVENT_*
194 * @kctl: the pointer with the control instance
195 * @ioff: the additional offset to the control index
197 * This function calls snd_ctl_notify() and does additional jobs
198 * like LED state changes.
200 void snd_ctl_notify_one(struct snd_card *card, unsigned int mask,
201 struct snd_kcontrol *kctl, unsigned int ioff)
203 struct snd_ctl_elem_id id = kctl->id;
204 struct snd_ctl_layer_ops *lops;
208 snd_ctl_notify(card, mask, &id);
209 guard(rwsem_read)(&snd_ctl_layer_rwsem);
210 for (lops = snd_ctl_layer; lops; lops = lops->next)
211 lops->lnotify(card, mask, kctl, ioff);
213 EXPORT_SYMBOL(snd_ctl_notify_one);
216 * snd_ctl_new - create a new control instance with some elements
217 * @kctl: the pointer to store new control instance
218 * @count: the number of elements in this control
219 * @access: the default access flags for elements in this control
220 * @file: given when locking these elements
222 * Allocates a memory object for a new control instance. The instance has
223 * elements as many as the given number (@count). Each element has given
224 * access permissions (@access). Each element is locked when @file is given.
226 * Return: 0 on success, error code on failure
228 static int snd_ctl_new(struct snd_kcontrol **kctl, unsigned int count,
229 unsigned int access, struct snd_ctl_file *file)
233 if (count == 0 || count > MAX_CONTROL_COUNT)
236 *kctl = kzalloc(struct_size(*kctl, vd, count), GFP_KERNEL);
240 (*kctl)->count = count;
241 for (idx = 0; idx < count; idx++) {
242 (*kctl)->vd[idx].access = access;
243 (*kctl)->vd[idx].owner = file;
250 * snd_ctl_new1 - create a control instance from the template
251 * @ncontrol: the initialization record
252 * @private_data: the private data to set
254 * Allocates a new struct snd_kcontrol instance and initialize from the given
255 * template. When the access field of ncontrol is 0, it's assumed as
256 * READWRITE access. When the count field is 0, it's assumes as one.
258 * Return: The pointer of the newly generated instance, or %NULL on failure.
260 struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new *ncontrol,
263 struct snd_kcontrol *kctl;
268 if (snd_BUG_ON(!ncontrol || !ncontrol->info))
271 count = ncontrol->count;
275 access = ncontrol->access;
277 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
278 access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
279 SNDRV_CTL_ELEM_ACCESS_VOLATILE |
280 SNDRV_CTL_ELEM_ACCESS_INACTIVE |
281 SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE |
282 SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND |
283 SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK |
284 SNDRV_CTL_ELEM_ACCESS_LED_MASK |
285 SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK);
287 err = snd_ctl_new(&kctl, count, access, NULL);
291 /* The 'numid' member is decided when calling snd_ctl_add(). */
292 kctl->id.iface = ncontrol->iface;
293 kctl->id.device = ncontrol->device;
294 kctl->id.subdevice = ncontrol->subdevice;
295 if (ncontrol->name) {
296 strscpy(kctl->id.name, ncontrol->name, sizeof(kctl->id.name));
297 if (strcmp(ncontrol->name, kctl->id.name) != 0)
298 pr_warn("ALSA: Control name '%s' truncated to '%s'\n",
299 ncontrol->name, kctl->id.name);
301 kctl->id.index = ncontrol->index;
303 kctl->info = ncontrol->info;
304 kctl->get = ncontrol->get;
305 kctl->put = ncontrol->put;
306 kctl->tlv.p = ncontrol->tlv.p;
308 kctl->private_value = ncontrol->private_value;
309 kctl->private_data = private_data;
313 EXPORT_SYMBOL(snd_ctl_new1);
316 * snd_ctl_free_one - release the control instance
317 * @kcontrol: the control instance
319 * Releases the control instance created via snd_ctl_new()
321 * Don't call this after the control was added to the card.
323 void snd_ctl_free_one(struct snd_kcontrol *kcontrol)
326 if (kcontrol->private_free)
327 kcontrol->private_free(kcontrol);
331 EXPORT_SYMBOL(snd_ctl_free_one);
333 static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
336 struct snd_kcontrol *kctl;
338 /* Make sure that the ids assigned to the control do not wrap around */
339 if (card->last_numid >= UINT_MAX - count)
340 card->last_numid = 0;
342 list_for_each_entry(kctl, &card->controls, list) {
343 if (kctl->id.numid < card->last_numid + 1 + count &&
344 kctl->id.numid + kctl->count > card->last_numid + 1) {
345 card->last_numid = kctl->id.numid + kctl->count - 1;
352 static int snd_ctl_find_hole(struct snd_card *card, unsigned int count)
354 unsigned int iter = 100000;
356 while (snd_ctl_remove_numid_conflict(card, count)) {
358 /* this situation is very unlikely */
359 dev_err(card->dev, "unable to allocate new control numid\n");
366 /* check whether the given id is contained in the given kctl */
367 static bool elem_id_matches(const struct snd_kcontrol *kctl,
368 const struct snd_ctl_elem_id *id)
370 return kctl->id.iface == id->iface &&
371 kctl->id.device == id->device &&
372 kctl->id.subdevice == id->subdevice &&
373 !strncmp(kctl->id.name, id->name, sizeof(kctl->id.name)) &&
374 kctl->id.index <= id->index &&
375 kctl->id.index + kctl->count > id->index;
378 #ifdef CONFIG_SND_CTL_FAST_LOOKUP
379 /* Compute a hash key for the corresponding ctl id
380 * It's for the name lookup, hence the numid is excluded.
381 * The hash key is bound in LONG_MAX to be used for Xarray key.
383 #define MULTIPLIER 37
384 static unsigned long get_ctl_id_hash(const struct snd_ctl_elem_id *id)
390 h = MULTIPLIER * h + id->device;
391 h = MULTIPLIER * h + id->subdevice;
392 for (i = 0; i < SNDRV_CTL_ELEM_ID_NAME_MAXLEN && id->name[i]; i++)
393 h = MULTIPLIER * h + id->name[i];
394 h = MULTIPLIER * h + id->index;
399 /* add hash entries to numid and ctl xarray tables */
400 static void add_hash_entries(struct snd_card *card,
401 struct snd_kcontrol *kcontrol)
403 struct snd_ctl_elem_id id = kcontrol->id;
406 xa_store_range(&card->ctl_numids, kcontrol->id.numid,
407 kcontrol->id.numid + kcontrol->count - 1,
408 kcontrol, GFP_KERNEL);
410 for (i = 0; i < kcontrol->count; i++) {
411 id.index = kcontrol->id.index + i;
412 if (xa_insert(&card->ctl_hash, get_ctl_id_hash(&id),
413 kcontrol, GFP_KERNEL)) {
414 /* skip hash for this entry, noting we had collision */
415 card->ctl_hash_collision = true;
416 dev_dbg(card->dev, "ctl_hash collision %d:%s:%d\n",
417 id.iface, id.name, id.index);
422 /* remove hash entries that have been added */
423 static void remove_hash_entries(struct snd_card *card,
424 struct snd_kcontrol *kcontrol)
426 struct snd_ctl_elem_id id = kcontrol->id;
427 struct snd_kcontrol *matched;
431 for (i = 0; i < kcontrol->count; i++) {
432 xa_erase(&card->ctl_numids, id.numid);
433 h = get_ctl_id_hash(&id);
434 matched = xa_load(&card->ctl_hash, h);
435 if (matched && (matched == kcontrol ||
436 elem_id_matches(matched, &id)))
437 xa_erase(&card->ctl_hash, h);
442 #else /* CONFIG_SND_CTL_FAST_LOOKUP */
443 static inline void add_hash_entries(struct snd_card *card,
444 struct snd_kcontrol *kcontrol)
447 static inline void remove_hash_entries(struct snd_card *card,
448 struct snd_kcontrol *kcontrol)
451 #endif /* CONFIG_SND_CTL_FAST_LOOKUP */
453 enum snd_ctl_add_mode {
454 CTL_ADD_EXCLUSIVE, CTL_REPLACE, CTL_ADD_ON_REPLACE,
457 /* add/replace a new kcontrol object; call with card->controls_rwsem locked */
458 static int __snd_ctl_add_replace(struct snd_card *card,
459 struct snd_kcontrol *kcontrol,
460 enum snd_ctl_add_mode mode)
462 struct snd_ctl_elem_id id;
464 struct snd_kcontrol *old;
467 lockdep_assert_held_write(&card->controls_rwsem);
470 if (id.index > UINT_MAX - kcontrol->count)
473 old = snd_ctl_find_id(card, &id);
475 if (mode == CTL_REPLACE)
478 if (mode == CTL_ADD_EXCLUSIVE) {
480 "control %i:%i:%i:%s:%i is already present\n",
481 id.iface, id.device, id.subdevice, id.name,
486 err = snd_ctl_remove_locked(card, old);
491 if (snd_ctl_find_hole(card, kcontrol->count) < 0)
494 scoped_guard(write_lock_irq, &card->controls_rwlock) {
495 list_add_tail(&kcontrol->list, &card->controls);
496 card->controls_count += kcontrol->count;
497 kcontrol->id.numid = card->last_numid + 1;
498 card->last_numid += kcontrol->count;
501 add_hash_entries(card, kcontrol);
503 for (idx = 0; idx < kcontrol->count; idx++)
504 snd_ctl_notify_one(card, SNDRV_CTL_EVENT_MASK_ADD, kcontrol, idx);
509 static int snd_ctl_add_replace(struct snd_card *card,
510 struct snd_kcontrol *kcontrol,
511 enum snd_ctl_add_mode mode)
517 if (snd_BUG_ON(!card || !kcontrol->info))
520 scoped_guard(rwsem_write, &card->controls_rwsem)
521 err = __snd_ctl_add_replace(card, kcontrol, mode);
528 snd_ctl_free_one(kcontrol);
533 * snd_ctl_add - add the control instance to the card
534 * @card: the card instance
535 * @kcontrol: the control instance to add
537 * Adds the control instance created via snd_ctl_new() or
538 * snd_ctl_new1() to the given card. Assigns also an unique
539 * numid used for fast search.
541 * It frees automatically the control which cannot be added.
543 * Return: Zero if successful, or a negative error code on failure.
546 int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
548 return snd_ctl_add_replace(card, kcontrol, CTL_ADD_EXCLUSIVE);
550 EXPORT_SYMBOL(snd_ctl_add);
553 * snd_ctl_replace - replace the control instance of the card
554 * @card: the card instance
555 * @kcontrol: the control instance to replace
556 * @add_on_replace: add the control if not already added
558 * Replaces the given control. If the given control does not exist
559 * and the add_on_replace flag is set, the control is added. If the
560 * control exists, it is destroyed first.
562 * It frees automatically the control which cannot be added or replaced.
564 * Return: Zero if successful, or a negative error code on failure.
566 int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
569 return snd_ctl_add_replace(card, kcontrol,
570 add_on_replace ? CTL_ADD_ON_REPLACE : CTL_REPLACE);
572 EXPORT_SYMBOL(snd_ctl_replace);
574 static int __snd_ctl_remove(struct snd_card *card,
575 struct snd_kcontrol *kcontrol,
580 lockdep_assert_held_write(&card->controls_rwsem);
582 if (snd_BUG_ON(!card || !kcontrol))
586 remove_hash_entries(card, kcontrol);
588 scoped_guard(write_lock_irq, &card->controls_rwlock) {
589 list_del(&kcontrol->list);
590 card->controls_count -= kcontrol->count;
593 for (idx = 0; idx < kcontrol->count; idx++)
594 snd_ctl_notify_one(card, SNDRV_CTL_EVENT_MASK_REMOVE, kcontrol, idx);
595 snd_ctl_free_one(kcontrol);
599 static inline int snd_ctl_remove_locked(struct snd_card *card,
600 struct snd_kcontrol *kcontrol)
602 return __snd_ctl_remove(card, kcontrol, true);
606 * snd_ctl_remove - remove the control from the card and release it
607 * @card: the card instance
608 * @kcontrol: the control instance to remove
610 * Removes the control from the card and then releases the instance.
611 * You don't need to call snd_ctl_free_one().
612 * Passing NULL to @kcontrol argument is allowed as noop.
614 * Return: 0 if successful, or a negative error code on failure.
616 * Note that this function takes card->controls_rwsem lock internally.
618 int snd_ctl_remove(struct snd_card *card, struct snd_kcontrol *kcontrol)
622 guard(rwsem_write)(&card->controls_rwsem);
623 return snd_ctl_remove_locked(card, kcontrol);
625 EXPORT_SYMBOL(snd_ctl_remove);
628 * snd_ctl_remove_id - remove the control of the given id and release it
629 * @card: the card instance
630 * @id: the control id to remove
632 * Finds the control instance with the given id, removes it from the
633 * card list and releases it.
635 * Return: 0 if successful, or a negative error code on failure.
637 int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
639 struct snd_kcontrol *kctl;
641 guard(rwsem_write)(&card->controls_rwsem);
642 kctl = snd_ctl_find_id(card, id);
645 return snd_ctl_remove_locked(card, kctl);
647 EXPORT_SYMBOL(snd_ctl_remove_id);
650 * snd_ctl_remove_user_ctl - remove and release the unlocked user control
651 * @file: active control handle
652 * @id: the control id to remove
654 * Finds the control instance with the given id, removes it from the
655 * card list and releases it.
657 * Return: 0 if successful, or a negative error code on failure.
659 static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
660 struct snd_ctl_elem_id *id)
662 struct snd_card *card = file->card;
663 struct snd_kcontrol *kctl;
666 guard(rwsem_write)(&card->controls_rwsem);
667 kctl = snd_ctl_find_id(card, id);
670 if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER))
672 for (idx = 0; idx < kctl->count; idx++)
673 if (kctl->vd[idx].owner != NULL && kctl->vd[idx].owner != file)
675 return snd_ctl_remove_locked(card, kctl);
679 * snd_ctl_activate_id - activate/inactivate the control of the given id
680 * @card: the card instance
681 * @id: the control id to activate/inactivate
682 * @active: non-zero to activate
684 * Finds the control instance with the given id, and activate or
685 * inactivate the control together with notification, if changed.
686 * The given ID data is filled with full information.
688 * Return: 0 if unchanged, 1 if changed, or a negative error code on failure.
690 int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
693 struct snd_kcontrol *kctl;
694 struct snd_kcontrol_volatile *vd;
695 unsigned int index_offset;
698 down_write(&card->controls_rwsem);
699 kctl = snd_ctl_find_id(card, id);
704 index_offset = snd_ctl_get_ioff(kctl, id);
705 vd = &kctl->vd[index_offset];
708 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
710 vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
712 if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
714 vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
716 snd_ctl_build_ioff(id, kctl, index_offset);
717 downgrade_write(&card->controls_rwsem);
718 snd_ctl_notify_one(card, SNDRV_CTL_EVENT_MASK_INFO, kctl, index_offset);
719 up_read(&card->controls_rwsem);
723 up_write(&card->controls_rwsem);
726 EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
729 * snd_ctl_rename_id - replace the id of a control on the card
730 * @card: the card instance
731 * @src_id: the old id
732 * @dst_id: the new id
734 * Finds the control with the old id from the card, and replaces the
735 * id with the new one.
737 * The function tries to keep the already assigned numid while replacing
740 * Note that this function should be used only in the card initialization
741 * phase. Calling after the card instantiation may cause issues with
742 * user-space expecting persistent numids.
744 * Return: Zero if successful, or a negative error code on failure.
746 int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
747 struct snd_ctl_elem_id *dst_id)
749 struct snd_kcontrol *kctl;
752 guard(rwsem_write)(&card->controls_rwsem);
753 kctl = snd_ctl_find_id(card, src_id);
756 saved_numid = kctl->id.numid;
757 remove_hash_entries(card, kctl);
759 kctl->id.numid = saved_numid;
760 add_hash_entries(card, kctl);
763 EXPORT_SYMBOL(snd_ctl_rename_id);
766 * snd_ctl_rename - rename the control on the card
767 * @card: the card instance
768 * @kctl: the control to rename
769 * @name: the new name
771 * Renames the specified control on the card to the new name.
773 * Note that this function takes card->controls_rwsem lock internally.
775 void snd_ctl_rename(struct snd_card *card, struct snd_kcontrol *kctl,
778 guard(rwsem_write)(&card->controls_rwsem);
779 remove_hash_entries(card, kctl);
781 if (strscpy(kctl->id.name, name, sizeof(kctl->id.name)) < 0)
782 pr_warn("ALSA: Renamed control new name '%s' truncated to '%s'\n",
783 name, kctl->id.name);
785 add_hash_entries(card, kctl);
787 EXPORT_SYMBOL(snd_ctl_rename);
789 #ifndef CONFIG_SND_CTL_FAST_LOOKUP
790 static struct snd_kcontrol *
791 snd_ctl_find_numid_slow(struct snd_card *card, unsigned int numid)
793 struct snd_kcontrol *kctl;
795 guard(read_lock_irqsave)(&card->controls_rwlock);
796 list_for_each_entry(kctl, &card->controls, list) {
797 if (kctl->id.numid <= numid && kctl->id.numid + kctl->count > numid)
802 #endif /* !CONFIG_SND_CTL_FAST_LOOKUP */
805 * snd_ctl_find_numid - find the control instance with the given number-id
806 * @card: the card instance
807 * @numid: the number-id to search
809 * Finds the control instance with the given number-id from the card.
811 * Return: The pointer of the instance if found, or %NULL if not.
813 * Note that this function takes card->controls_rwlock lock internally.
815 struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card,
818 if (snd_BUG_ON(!card || !numid))
821 #ifdef CONFIG_SND_CTL_FAST_LOOKUP
822 return xa_load(&card->ctl_numids, numid);
824 return snd_ctl_find_numid_slow(card, numid);
827 EXPORT_SYMBOL(snd_ctl_find_numid);
830 * snd_ctl_find_id - find the control instance with the given id
831 * @card: the card instance
832 * @id: the id to search
834 * Finds the control instance with the given id from the card.
836 * Return: The pointer of the instance if found, or %NULL if not.
838 * Note that this function takes card->controls_rwlock lock internally.
840 struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
841 const struct snd_ctl_elem_id *id)
843 struct snd_kcontrol *kctl;
845 if (snd_BUG_ON(!card || !id))
849 return snd_ctl_find_numid(card, id->numid);
850 #ifdef CONFIG_SND_CTL_FAST_LOOKUP
851 kctl = xa_load(&card->ctl_hash, get_ctl_id_hash(id));
852 if (kctl && elem_id_matches(kctl, id))
854 if (!card->ctl_hash_collision)
855 return NULL; /* we can rely on only hash table */
857 /* no matching in hash table - try all as the last resort */
858 guard(read_lock_irqsave)(&card->controls_rwlock);
859 list_for_each_entry(kctl, &card->controls, list)
860 if (elem_id_matches(kctl, id))
865 EXPORT_SYMBOL(snd_ctl_find_id);
867 static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,
868 unsigned int cmd, void __user *arg)
870 struct snd_ctl_card_info *info __free(kfree) = NULL;
872 info = kzalloc(sizeof(*info), GFP_KERNEL);
875 scoped_guard(rwsem_read, &snd_ioctl_rwsem) {
876 info->card = card->number;
877 strscpy(info->id, card->id, sizeof(info->id));
878 strscpy(info->driver, card->driver, sizeof(info->driver));
879 strscpy(info->name, card->shortname, sizeof(info->name));
880 strscpy(info->longname, card->longname, sizeof(info->longname));
881 strscpy(info->mixername, card->mixername, sizeof(info->mixername));
882 strscpy(info->components, card->components, sizeof(info->components));
884 if (copy_to_user(arg, info, sizeof(struct snd_ctl_card_info)))
889 static int snd_ctl_elem_list(struct snd_card *card,
890 struct snd_ctl_elem_list *list)
892 struct snd_kcontrol *kctl;
893 struct snd_ctl_elem_id id;
894 unsigned int offset, space, jidx;
896 offset = list->offset;
899 guard(rwsem_read)(&card->controls_rwsem);
900 list->count = card->controls_count;
904 list_for_each_entry(kctl, &card->controls, list) {
905 if (offset >= kctl->count) {
906 offset -= kctl->count;
909 for (jidx = offset; jidx < kctl->count; jidx++) {
910 snd_ctl_build_ioff(&id, kctl, jidx);
911 if (copy_to_user(list->pids + list->used, &id, sizeof(id)))
922 static int snd_ctl_elem_list_user(struct snd_card *card,
923 struct snd_ctl_elem_list __user *_list)
925 struct snd_ctl_elem_list list;
928 if (copy_from_user(&list, _list, sizeof(list)))
930 err = snd_ctl_elem_list(card, &list);
933 if (copy_to_user(_list, &list, sizeof(list)))
939 /* Check whether the given kctl info is valid */
940 static int snd_ctl_check_elem_info(struct snd_card *card,
941 const struct snd_ctl_elem_info *info)
943 static const unsigned int max_value_counts[] = {
944 [SNDRV_CTL_ELEM_TYPE_BOOLEAN] = 128,
945 [SNDRV_CTL_ELEM_TYPE_INTEGER] = 128,
946 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = 128,
947 [SNDRV_CTL_ELEM_TYPE_BYTES] = 512,
948 [SNDRV_CTL_ELEM_TYPE_IEC958] = 1,
949 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = 64,
952 if (info->type < SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
953 info->type > SNDRV_CTL_ELEM_TYPE_INTEGER64) {
956 "control %i:%i:%i:%s:%i: invalid type %d\n",
957 info->id.iface, info->id.device,
958 info->id.subdevice, info->id.name,
959 info->id.index, info->type);
962 if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED &&
963 info->value.enumerated.items == 0) {
966 "control %i:%i:%i:%s:%i: zero enum items\n",
967 info->id.iface, info->id.device,
968 info->id.subdevice, info->id.name,
972 if (info->count > max_value_counts[info->type]) {
975 "control %i:%i:%i:%s:%i: invalid count %d\n",
976 info->id.iface, info->id.device,
977 info->id.subdevice, info->id.name,
978 info->id.index, info->count);
985 /* The capacity of struct snd_ctl_elem_value.value.*/
986 static const unsigned int value_sizes[] = {
987 [SNDRV_CTL_ELEM_TYPE_BOOLEAN] = sizeof(long),
988 [SNDRV_CTL_ELEM_TYPE_INTEGER] = sizeof(long),
989 [SNDRV_CTL_ELEM_TYPE_ENUMERATED] = sizeof(unsigned int),
990 [SNDRV_CTL_ELEM_TYPE_BYTES] = sizeof(unsigned char),
991 [SNDRV_CTL_ELEM_TYPE_IEC958] = sizeof(struct snd_aes_iec958),
992 [SNDRV_CTL_ELEM_TYPE_INTEGER64] = sizeof(long long),
995 /* fill the remaining snd_ctl_elem_value data with the given pattern */
996 static void fill_remaining_elem_value(struct snd_ctl_elem_value *control,
997 struct snd_ctl_elem_info *info,
1000 size_t offset = value_sizes[info->type] * info->count;
1002 offset = DIV_ROUND_UP(offset, sizeof(u32));
1003 memset32((u32 *)control->value.bytes.data + offset, pattern,
1004 sizeof(control->value) / sizeof(u32) - offset);
1007 /* check whether the given integer ctl value is valid */
1008 static int sanity_check_int_value(struct snd_card *card,
1009 const struct snd_ctl_elem_value *control,
1010 const struct snd_ctl_elem_info *info,
1011 int i, bool print_error)
1013 long long lval, lmin, lmax, lstep;
1016 switch (info->type) {
1018 case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
1019 lval = control->value.integer.value[i];
1024 case SNDRV_CTL_ELEM_TYPE_INTEGER:
1025 lval = control->value.integer.value[i];
1026 lmin = info->value.integer.min;
1027 lmax = info->value.integer.max;
1028 lstep = info->value.integer.step;
1030 case SNDRV_CTL_ELEM_TYPE_INTEGER64:
1031 lval = control->value.integer64.value[i];
1032 lmin = info->value.integer64.min;
1033 lmax = info->value.integer64.max;
1034 lstep = info->value.integer64.step;
1036 case SNDRV_CTL_ELEM_TYPE_ENUMERATED:
1037 lval = control->value.enumerated.item[i];
1039 lmax = info->value.enumerated.items - 1;
1044 if (lval < lmin || lval > lmax) {
1047 "control %i:%i:%i:%s:%i: value out of range %lld (%lld/%lld) at count %i\n",
1048 control->id.iface, control->id.device,
1049 control->id.subdevice, control->id.name,
1050 control->id.index, lval, lmin, lmax, i);
1054 div64_u64_rem(lval, lstep, &rem);
1058 "control %i:%i:%i:%s:%i: unaligned value %lld (step %lld) at count %i\n",
1059 control->id.iface, control->id.device,
1060 control->id.subdevice, control->id.name,
1061 control->id.index, lval, lstep, i);
1069 /* check whether the all input values are valid for the given elem value */
1070 static int sanity_check_input_values(struct snd_card *card,
1071 const struct snd_ctl_elem_value *control,
1072 const struct snd_ctl_elem_info *info,
1077 switch (info->type) {
1078 case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
1079 case SNDRV_CTL_ELEM_TYPE_INTEGER:
1080 case SNDRV_CTL_ELEM_TYPE_INTEGER64:
1081 case SNDRV_CTL_ELEM_TYPE_ENUMERATED:
1082 for (i = 0; i < info->count; i++) {
1083 ret = sanity_check_int_value(card, control, info, i,
1096 /* perform sanity checks to the given snd_ctl_elem_value object */
1097 static int sanity_check_elem_value(struct snd_card *card,
1098 const struct snd_ctl_elem_value *control,
1099 const struct snd_ctl_elem_info *info,
1106 ret = sanity_check_input_values(card, control, info, true);
1110 /* check whether the remaining area kept untouched */
1111 offset = value_sizes[info->type] * info->count;
1112 offset = DIV_ROUND_UP(offset, sizeof(u32));
1113 p = (u32 *)control->value.bytes.data + offset;
1114 for (; offset < sizeof(control->value) / sizeof(u32); offset++, p++) {
1115 if (*p != pattern) {
1119 *p = 0; /* clear the checked area */
1125 static int __snd_ctl_elem_info(struct snd_card *card,
1126 struct snd_kcontrol *kctl,
1127 struct snd_ctl_elem_info *info,
1128 struct snd_ctl_file *ctl)
1130 struct snd_kcontrol_volatile *vd;
1131 unsigned int index_offset;
1134 #ifdef CONFIG_SND_DEBUG
1137 result = kctl->info(kctl, info);
1139 snd_BUG_ON(info->access);
1140 index_offset = snd_ctl_get_ioff(kctl, &info->id);
1141 vd = &kctl->vd[index_offset];
1142 snd_ctl_build_ioff(&info->id, kctl, index_offset);
1143 info->access = vd->access;
1145 info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
1146 if (vd->owner == ctl)
1147 info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
1148 info->owner = pid_vnr(vd->owner->pid);
1152 if (!snd_ctl_skip_validation(info) &&
1153 snd_ctl_check_elem_info(card, info) < 0)
1159 static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
1160 struct snd_ctl_elem_info *info)
1162 struct snd_card *card = ctl->card;
1163 struct snd_kcontrol *kctl;
1165 guard(rwsem_read)(&card->controls_rwsem);
1166 kctl = snd_ctl_find_id(card, &info->id);
1169 return __snd_ctl_elem_info(card, kctl, info, ctl);
1172 static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
1173 struct snd_ctl_elem_info __user *_info)
1175 struct snd_card *card = ctl->card;
1176 struct snd_ctl_elem_info info;
1179 if (copy_from_user(&info, _info, sizeof(info)))
1181 result = snd_power_ref_and_wait(card);
1184 result = snd_ctl_elem_info(ctl, &info);
1185 snd_power_unref(card);
1188 /* drop internal access flags */
1189 info.access &= ~(SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK|
1190 SNDRV_CTL_ELEM_ACCESS_LED_MASK);
1191 if (copy_to_user(_info, &info, sizeof(info)))
1196 static int snd_ctl_elem_read(struct snd_card *card,
1197 struct snd_ctl_elem_value *control)
1199 struct snd_kcontrol *kctl;
1200 struct snd_kcontrol_volatile *vd;
1201 unsigned int index_offset;
1202 struct snd_ctl_elem_info info;
1203 const u32 pattern = 0xdeadbeef;
1206 guard(rwsem_read)(&card->controls_rwsem);
1207 kctl = snd_ctl_find_id(card, &control->id);
1211 index_offset = snd_ctl_get_ioff(kctl, &control->id);
1212 vd = &kctl->vd[index_offset];
1213 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_READ) || !kctl->get)
1216 snd_ctl_build_ioff(&control->id, kctl, index_offset);
1218 #ifdef CONFIG_SND_CTL_DEBUG
1219 /* info is needed only for validation */
1220 memset(&info, 0, sizeof(info));
1221 info.id = control->id;
1222 ret = __snd_ctl_elem_info(card, kctl, &info, NULL);
1227 if (!snd_ctl_skip_validation(&info))
1228 fill_remaining_elem_value(control, &info, pattern);
1229 ret = kctl->get(kctl, control);
1232 if (!snd_ctl_skip_validation(&info) &&
1233 sanity_check_elem_value(card, control, &info, pattern) < 0) {
1235 "control %i:%i:%i:%s:%i: access overflow\n",
1236 control->id.iface, control->id.device,
1237 control->id.subdevice, control->id.name,
1244 static int snd_ctl_elem_read_user(struct snd_card *card,
1245 struct snd_ctl_elem_value __user *_control)
1247 struct snd_ctl_elem_value *control __free(kfree) = NULL;
1250 control = memdup_user(_control, sizeof(*control));
1251 if (IS_ERR(control))
1252 return PTR_ERR(control);
1254 result = snd_power_ref_and_wait(card);
1257 result = snd_ctl_elem_read(card, control);
1258 snd_power_unref(card);
1262 if (copy_to_user(_control, control, sizeof(*control)))
1267 static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
1268 struct snd_ctl_elem_value *control)
1270 struct snd_kcontrol *kctl;
1271 struct snd_kcontrol_volatile *vd;
1272 unsigned int index_offset;
1275 down_write(&card->controls_rwsem);
1276 kctl = snd_ctl_find_id(card, &control->id);
1278 up_write(&card->controls_rwsem);
1282 index_offset = snd_ctl_get_ioff(kctl, &control->id);
1283 vd = &kctl->vd[index_offset];
1284 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_WRITE) || kctl->put == NULL ||
1285 (file && vd->owner && vd->owner != file)) {
1286 up_write(&card->controls_rwsem);
1290 snd_ctl_build_ioff(&control->id, kctl, index_offset);
1291 /* validate input values */
1292 if (IS_ENABLED(CONFIG_SND_CTL_INPUT_VALIDATION)) {
1293 struct snd_ctl_elem_info info;
1295 memset(&info, 0, sizeof(info));
1296 info.id = control->id;
1297 result = __snd_ctl_elem_info(card, kctl, &info, NULL);
1299 result = sanity_check_input_values(card, control, &info,
1303 result = kctl->put(kctl, control);
1305 up_write(&card->controls_rwsem);
1310 downgrade_write(&card->controls_rwsem);
1311 snd_ctl_notify_one(card, SNDRV_CTL_EVENT_MASK_VALUE, kctl, index_offset);
1312 up_read(&card->controls_rwsem);
1314 up_write(&card->controls_rwsem);
1320 static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
1321 struct snd_ctl_elem_value __user *_control)
1323 struct snd_ctl_elem_value *control __free(kfree) = NULL;
1324 struct snd_card *card;
1327 control = memdup_user(_control, sizeof(*control));
1328 if (IS_ERR(control))
1329 return PTR_ERR(control);
1332 result = snd_power_ref_and_wait(card);
1335 result = snd_ctl_elem_write(card, file, control);
1336 snd_power_unref(card);
1340 if (copy_to_user(_control, control, sizeof(*control)))
1345 static int snd_ctl_elem_lock(struct snd_ctl_file *file,
1346 struct snd_ctl_elem_id __user *_id)
1348 struct snd_card *card = file->card;
1349 struct snd_ctl_elem_id id;
1350 struct snd_kcontrol *kctl;
1351 struct snd_kcontrol_volatile *vd;
1353 if (copy_from_user(&id, _id, sizeof(id)))
1355 guard(rwsem_write)(&card->controls_rwsem);
1356 kctl = snd_ctl_find_id(card, &id);
1359 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1366 static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
1367 struct snd_ctl_elem_id __user *_id)
1369 struct snd_card *card = file->card;
1370 struct snd_ctl_elem_id id;
1371 struct snd_kcontrol *kctl;
1372 struct snd_kcontrol_volatile *vd;
1374 if (copy_from_user(&id, _id, sizeof(id)))
1376 guard(rwsem_write)(&card->controls_rwsem);
1377 kctl = snd_ctl_find_id(card, &id);
1380 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1383 if (vd->owner != file)
1389 struct user_element {
1390 struct snd_ctl_elem_info info;
1391 struct snd_card *card;
1392 char *elem_data; /* element data */
1393 unsigned long elem_data_size; /* size of element data in bytes */
1394 void *tlv_data; /* TLV data */
1395 unsigned long tlv_data_size; /* TLV data size */
1396 void *priv_data; /* private data (like strings for enumerated type) */
1399 // check whether the addition (in bytes) of user ctl element may overflow the limit.
1400 static bool check_user_elem_overflow(struct snd_card *card, ssize_t add)
1402 return (ssize_t)card->user_ctl_alloc_size + add > max_user_ctl_alloc_size;
1405 static int snd_ctl_elem_user_info(struct snd_kcontrol *kcontrol,
1406 struct snd_ctl_elem_info *uinfo)
1408 struct user_element *ue = kcontrol->private_data;
1409 unsigned int offset;
1411 offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1413 snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1418 static int snd_ctl_elem_user_enum_info(struct snd_kcontrol *kcontrol,
1419 struct snd_ctl_elem_info *uinfo)
1421 struct user_element *ue = kcontrol->private_data;
1424 unsigned int offset;
1426 item = uinfo->value.enumerated.item;
1428 offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);
1430 snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);
1432 item = min(item, uinfo->value.enumerated.items - 1);
1433 uinfo->value.enumerated.item = item;
1435 names = ue->priv_data;
1436 for (; item > 0; --item)
1437 names += strlen(names) + 1;
1438 strcpy(uinfo->value.enumerated.name, names);
1443 static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
1444 struct snd_ctl_elem_value *ucontrol)
1446 struct user_element *ue = kcontrol->private_data;
1447 unsigned int size = ue->elem_data_size;
1448 char *src = ue->elem_data +
1449 snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1451 memcpy(&ucontrol->value, src, size);
1455 static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
1456 struct snd_ctl_elem_value *ucontrol)
1459 struct user_element *ue = kcontrol->private_data;
1460 unsigned int size = ue->elem_data_size;
1461 char *dst = ue->elem_data +
1462 snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;
1464 err = sanity_check_input_values(ue->card, ucontrol, &ue->info, false);
1468 change = memcmp(&ucontrol->value, dst, size) != 0;
1470 memcpy(dst, &ucontrol->value, size);
1474 /* called in controls_rwsem write lock */
1475 static int replace_user_tlv(struct snd_kcontrol *kctl, unsigned int __user *buf,
1478 struct user_element *ue = kctl->private_data;
1479 unsigned int *container;
1480 unsigned int mask = 0;
1484 lockdep_assert_held_write(&ue->card->controls_rwsem);
1486 if (size > 1024 * 128) /* sane value */
1489 // does the TLV size change cause overflow?
1490 if (check_user_elem_overflow(ue->card, (ssize_t)(size - ue->tlv_data_size)))
1493 container = vmemdup_user(buf, size);
1494 if (IS_ERR(container))
1495 return PTR_ERR(container);
1497 change = ue->tlv_data_size != size;
1499 change = memcmp(ue->tlv_data, container, size) != 0;
1505 if (ue->tlv_data == NULL) {
1506 /* Now TLV data is available. */
1507 for (i = 0; i < kctl->count; ++i)
1508 kctl->vd[i].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
1509 mask = SNDRV_CTL_EVENT_MASK_INFO;
1511 ue->card->user_ctl_alloc_size -= ue->tlv_data_size;
1512 ue->tlv_data_size = 0;
1513 kvfree(ue->tlv_data);
1516 ue->tlv_data = container;
1517 ue->tlv_data_size = size;
1518 // decremented at private_free.
1519 ue->card->user_ctl_alloc_size += size;
1521 mask |= SNDRV_CTL_EVENT_MASK_TLV;
1522 for (i = 0; i < kctl->count; ++i)
1523 snd_ctl_notify_one(ue->card, mask, kctl, i);
1528 static int read_user_tlv(struct snd_kcontrol *kctl, unsigned int __user *buf,
1531 struct user_element *ue = kctl->private_data;
1533 if (ue->tlv_data_size == 0 || ue->tlv_data == NULL)
1536 if (size < ue->tlv_data_size)
1539 if (copy_to_user(buf, ue->tlv_data, ue->tlv_data_size))
1545 static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kctl, int op_flag,
1546 unsigned int size, unsigned int __user *buf)
1548 if (op_flag == SNDRV_CTL_TLV_OP_WRITE)
1549 return replace_user_tlv(kctl, buf, size);
1551 return read_user_tlv(kctl, buf, size);
1554 /* called in controls_rwsem write lock */
1555 static int snd_ctl_elem_init_enum_names(struct user_element *ue)
1558 size_t buf_len, name_len;
1560 const uintptr_t user_ptrval = ue->info.value.enumerated.names_ptr;
1562 lockdep_assert_held_write(&ue->card->controls_rwsem);
1564 buf_len = ue->info.value.enumerated.names_length;
1565 if (buf_len > 64 * 1024)
1568 if (check_user_elem_overflow(ue->card, buf_len))
1570 names = vmemdup_user((const void __user *)user_ptrval, buf_len);
1572 return PTR_ERR(names);
1574 /* check that there are enough valid names */
1576 for (i = 0; i < ue->info.value.enumerated.items; ++i) {
1577 name_len = strnlen(p, buf_len);
1578 if (name_len == 0 || name_len >= 64 || name_len == buf_len) {
1583 buf_len -= name_len + 1;
1586 ue->priv_data = names;
1587 ue->info.value.enumerated.names_ptr = 0;
1588 // increment the allocation size; decremented again at private_free.
1589 ue->card->user_ctl_alloc_size += ue->info.value.enumerated.names_length;
1594 static size_t compute_user_elem_size(size_t size, unsigned int count)
1596 return sizeof(struct user_element) + size * count;
1599 static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)
1601 struct user_element *ue = kcontrol->private_data;
1603 // decrement the allocation size.
1604 ue->card->user_ctl_alloc_size -= compute_user_elem_size(ue->elem_data_size, kcontrol->count);
1605 ue->card->user_ctl_alloc_size -= ue->tlv_data_size;
1607 ue->card->user_ctl_alloc_size -= ue->info.value.enumerated.names_length;
1609 kvfree(ue->tlv_data);
1610 kvfree(ue->priv_data);
1614 static int snd_ctl_elem_add(struct snd_ctl_file *file,
1615 struct snd_ctl_elem_info *info, int replace)
1617 struct snd_card *card = file->card;
1618 struct snd_kcontrol *kctl;
1620 unsigned int access;
1623 struct user_element *ue;
1624 unsigned int offset;
1627 if (!*info->id.name)
1629 if (strnlen(info->id.name, sizeof(info->id.name)) >= sizeof(info->id.name))
1632 /* Delete a control to replace them if needed. */
1635 err = snd_ctl_remove_user_ctl(file, &info->id);
1640 /* Check the number of elements for this userspace control. */
1641 count = info->owner;
1645 /* Arrange access permissions if needed. */
1646 access = info->access;
1648 access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
1649 access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
1650 SNDRV_CTL_ELEM_ACCESS_INACTIVE |
1651 SNDRV_CTL_ELEM_ACCESS_TLV_WRITE);
1653 /* In initial state, nothing is available as TLV container. */
1654 if (access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE)
1655 access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
1656 access |= SNDRV_CTL_ELEM_ACCESS_USER;
1659 * Check information and calculate the size of data specific to
1660 * this userspace control.
1662 /* pass NULL to card for suppressing error messages */
1663 err = snd_ctl_check_elem_info(NULL, info);
1666 /* user-space control doesn't allow zero-size data */
1667 if (info->count < 1)
1669 private_size = value_sizes[info->type] * info->count;
1670 alloc_size = compute_user_elem_size(private_size, count);
1672 guard(rwsem_write)(&card->controls_rwsem);
1673 if (check_user_elem_overflow(card, alloc_size))
1677 * Keep memory object for this userspace control. After passing this
1678 * code block, the instance should be freed by snd_ctl_free_one().
1680 * Note that these elements in this control are locked.
1682 err = snd_ctl_new(&kctl, count, access, file);
1685 memcpy(&kctl->id, &info->id, sizeof(kctl->id));
1686 ue = kzalloc(alloc_size, GFP_KERNEL);
1691 kctl->private_data = ue;
1692 kctl->private_free = snd_ctl_elem_user_free;
1694 // increment the allocated size; decremented again at private_free.
1695 card->user_ctl_alloc_size += alloc_size;
1697 /* Set private data for this userspace control. */
1700 ue->info.access = 0;
1701 ue->elem_data = (char *)ue + sizeof(*ue);
1702 ue->elem_data_size = private_size;
1703 if (ue->info.type == SNDRV_CTL_ELEM_TYPE_ENUMERATED) {
1704 err = snd_ctl_elem_init_enum_names(ue);
1706 snd_ctl_free_one(kctl);
1711 /* Set callback functions. */
1712 if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
1713 kctl->info = snd_ctl_elem_user_enum_info;
1715 kctl->info = snd_ctl_elem_user_info;
1716 if (access & SNDRV_CTL_ELEM_ACCESS_READ)
1717 kctl->get = snd_ctl_elem_user_get;
1718 if (access & SNDRV_CTL_ELEM_ACCESS_WRITE)
1719 kctl->put = snd_ctl_elem_user_put;
1720 if (access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE)
1721 kctl->tlv.c = snd_ctl_elem_user_tlv;
1723 /* This function manage to free the instance on failure. */
1724 err = __snd_ctl_add_replace(card, kctl, CTL_ADD_EXCLUSIVE);
1726 snd_ctl_free_one(kctl);
1729 offset = snd_ctl_get_ioff(kctl, &info->id);
1730 snd_ctl_build_ioff(&info->id, kctl, offset);
1732 * Here we cannot fill any field for the number of elements added by
1733 * this operation because there're no specific fields. The usage of
1734 * 'owner' field for this purpose may cause any bugs to userspace
1735 * applications because the field originally means PID of a process
1736 * which locks the element.
1741 static int snd_ctl_elem_add_user(struct snd_ctl_file *file,
1742 struct snd_ctl_elem_info __user *_info, int replace)
1744 struct snd_ctl_elem_info info;
1747 if (copy_from_user(&info, _info, sizeof(info)))
1749 err = snd_ctl_elem_add(file, &info, replace);
1752 if (copy_to_user(_info, &info, sizeof(info))) {
1753 snd_ctl_remove_user_ctl(file, &info.id);
1760 static int snd_ctl_elem_remove(struct snd_ctl_file *file,
1761 struct snd_ctl_elem_id __user *_id)
1763 struct snd_ctl_elem_id id;
1765 if (copy_from_user(&id, _id, sizeof(id)))
1767 return snd_ctl_remove_user_ctl(file, &id);
1770 static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
1773 if (get_user(subscribe, ptr))
1775 if (subscribe < 0) {
1776 subscribe = file->subscribed;
1777 if (put_user(subscribe, ptr))
1782 file->subscribed = 1;
1784 } else if (file->subscribed) {
1785 snd_ctl_empty_read_queue(file);
1786 file->subscribed = 0;
1791 static int call_tlv_handler(struct snd_ctl_file *file, int op_flag,
1792 struct snd_kcontrol *kctl,
1793 struct snd_ctl_elem_id *id,
1794 unsigned int __user *buf, unsigned int size)
1796 static const struct {
1800 {SNDRV_CTL_TLV_OP_READ, SNDRV_CTL_ELEM_ACCESS_TLV_READ},
1801 {SNDRV_CTL_TLV_OP_WRITE, SNDRV_CTL_ELEM_ACCESS_TLV_WRITE},
1802 {SNDRV_CTL_TLV_OP_CMD, SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND},
1804 struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)];
1807 /* Check support of the request for this element. */
1808 for (i = 0; i < ARRAY_SIZE(pairs); ++i) {
1809 if (op_flag == pairs[i].op && (vd->access & pairs[i].perm))
1812 if (i == ARRAY_SIZE(pairs))
1815 if (kctl->tlv.c == NULL)
1818 /* Write and command operations are not allowed for locked element. */
1819 if (op_flag != SNDRV_CTL_TLV_OP_READ &&
1820 vd->owner != NULL && vd->owner != file)
1823 return kctl->tlv.c(kctl, op_flag, size, buf);
1826 static int read_tlv_buf(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id,
1827 unsigned int __user *buf, unsigned int size)
1829 struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)];
1832 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ))
1835 if (kctl->tlv.p == NULL)
1838 len = sizeof(unsigned int) * 2 + kctl->tlv.p[1];
1842 if (copy_to_user(buf, kctl->tlv.p, len))
1848 static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
1849 struct snd_ctl_tlv __user *buf,
1852 struct snd_ctl_tlv header;
1853 unsigned int __user *container;
1854 unsigned int container_size;
1855 struct snd_kcontrol *kctl;
1856 struct snd_ctl_elem_id id;
1857 struct snd_kcontrol_volatile *vd;
1859 lockdep_assert_held(&file->card->controls_rwsem);
1861 if (copy_from_user(&header, buf, sizeof(header)))
1864 /* In design of control core, numerical ID starts at 1. */
1865 if (header.numid == 0)
1868 /* At least, container should include type and length fields. */
1869 if (header.length < sizeof(unsigned int) * 2)
1871 container_size = header.length;
1872 container = buf->tlv;
1874 kctl = snd_ctl_find_numid(file->card, header.numid);
1878 /* Calculate index of the element in this set. */
1880 snd_ctl_build_ioff(&id, kctl, header.numid - id.numid);
1881 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
1883 if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
1884 return call_tlv_handler(file, op_flag, kctl, &id, container,
1887 if (op_flag == SNDRV_CTL_TLV_OP_READ) {
1888 return read_tlv_buf(kctl, &id, container,
1893 /* Not supported. */
1897 static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1899 struct snd_ctl_file *ctl;
1900 struct snd_card *card;
1901 struct snd_kctl_ioctl *p;
1902 void __user *argp = (void __user *)arg;
1903 int __user *ip = argp;
1906 ctl = file->private_data;
1908 if (snd_BUG_ON(!card))
1911 case SNDRV_CTL_IOCTL_PVERSION:
1912 return put_user(SNDRV_CTL_VERSION, ip) ? -EFAULT : 0;
1913 case SNDRV_CTL_IOCTL_CARD_INFO:
1914 return snd_ctl_card_info(card, ctl, cmd, argp);
1915 case SNDRV_CTL_IOCTL_ELEM_LIST:
1916 return snd_ctl_elem_list_user(card, argp);
1917 case SNDRV_CTL_IOCTL_ELEM_INFO:
1918 return snd_ctl_elem_info_user(ctl, argp);
1919 case SNDRV_CTL_IOCTL_ELEM_READ:
1920 return snd_ctl_elem_read_user(card, argp);
1921 case SNDRV_CTL_IOCTL_ELEM_WRITE:
1922 return snd_ctl_elem_write_user(ctl, argp);
1923 case SNDRV_CTL_IOCTL_ELEM_LOCK:
1924 return snd_ctl_elem_lock(ctl, argp);
1925 case SNDRV_CTL_IOCTL_ELEM_UNLOCK:
1926 return snd_ctl_elem_unlock(ctl, argp);
1927 case SNDRV_CTL_IOCTL_ELEM_ADD:
1928 return snd_ctl_elem_add_user(ctl, argp, 0);
1929 case SNDRV_CTL_IOCTL_ELEM_REPLACE:
1930 return snd_ctl_elem_add_user(ctl, argp, 1);
1931 case SNDRV_CTL_IOCTL_ELEM_REMOVE:
1932 return snd_ctl_elem_remove(ctl, argp);
1933 case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
1934 return snd_ctl_subscribe_events(ctl, ip);
1935 case SNDRV_CTL_IOCTL_TLV_READ:
1936 err = snd_power_ref_and_wait(card);
1939 scoped_guard(rwsem_read, &card->controls_rwsem)
1940 err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_READ);
1941 snd_power_unref(card);
1943 case SNDRV_CTL_IOCTL_TLV_WRITE:
1944 err = snd_power_ref_and_wait(card);
1947 scoped_guard(rwsem_write, &card->controls_rwsem)
1948 err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_WRITE);
1949 snd_power_unref(card);
1951 case SNDRV_CTL_IOCTL_TLV_COMMAND:
1952 err = snd_power_ref_and_wait(card);
1955 scoped_guard(rwsem_write, &card->controls_rwsem)
1956 err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_CMD);
1957 snd_power_unref(card);
1959 case SNDRV_CTL_IOCTL_POWER:
1960 return -ENOPROTOOPT;
1961 case SNDRV_CTL_IOCTL_POWER_STATE:
1962 return put_user(SNDRV_CTL_POWER_D0, ip) ? -EFAULT : 0;
1965 guard(rwsem_read)(&snd_ioctl_rwsem);
1966 list_for_each_entry(p, &snd_control_ioctls, list) {
1967 err = p->fioctl(card, ctl, cmd, arg);
1968 if (err != -ENOIOCTLCMD)
1971 dev_dbg(card->dev, "unknown ioctl = 0x%x\n", cmd);
1975 static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
1976 size_t count, loff_t * offset)
1978 struct snd_ctl_file *ctl;
1982 ctl = file->private_data;
1983 if (snd_BUG_ON(!ctl || !ctl->card))
1985 if (!ctl->subscribed)
1987 if (count < sizeof(struct snd_ctl_event))
1989 spin_lock_irq(&ctl->read_lock);
1990 while (count >= sizeof(struct snd_ctl_event)) {
1991 struct snd_ctl_event ev;
1992 struct snd_kctl_event *kev;
1993 while (list_empty(&ctl->events)) {
1994 wait_queue_entry_t wait;
1995 if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
1999 init_waitqueue_entry(&wait, current);
2000 add_wait_queue(&ctl->change_sleep, &wait);
2001 set_current_state(TASK_INTERRUPTIBLE);
2002 spin_unlock_irq(&ctl->read_lock);
2004 remove_wait_queue(&ctl->change_sleep, &wait);
2005 if (ctl->card->shutdown)
2007 if (signal_pending(current))
2008 return -ERESTARTSYS;
2009 spin_lock_irq(&ctl->read_lock);
2011 kev = snd_kctl_event(ctl->events.next);
2012 ev.type = SNDRV_CTL_EVENT_ELEM;
2013 ev.data.elem.mask = kev->mask;
2014 ev.data.elem.id = kev->id;
2015 list_del(&kev->list);
2016 spin_unlock_irq(&ctl->read_lock);
2018 if (copy_to_user(buffer, &ev, sizeof(struct snd_ctl_event))) {
2022 spin_lock_irq(&ctl->read_lock);
2023 buffer += sizeof(struct snd_ctl_event);
2024 count -= sizeof(struct snd_ctl_event);
2025 result += sizeof(struct snd_ctl_event);
2028 spin_unlock_irq(&ctl->read_lock);
2030 return result > 0 ? result : err;
2033 static __poll_t snd_ctl_poll(struct file *file, poll_table * wait)
2036 struct snd_ctl_file *ctl;
2038 ctl = file->private_data;
2039 if (!ctl->subscribed)
2041 poll_wait(file, &ctl->change_sleep, wait);
2044 if (!list_empty(&ctl->events))
2045 mask |= EPOLLIN | EPOLLRDNORM;
2051 * register the device-specific control-ioctls.
2052 * called from each device manager like pcm.c, hwdep.c, etc.
2054 static int _snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn, struct list_head *lists)
2056 struct snd_kctl_ioctl *pn;
2058 pn = kzalloc(sizeof(struct snd_kctl_ioctl), GFP_KERNEL);
2062 guard(rwsem_write)(&snd_ioctl_rwsem);
2063 list_add_tail(&pn->list, lists);
2068 * snd_ctl_register_ioctl - register the device-specific control-ioctls
2069 * @fcn: ioctl callback function
2071 * called from each device manager like pcm.c, hwdep.c, etc.
2073 * Return: zero if successful, or a negative error code
2075 int snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn)
2077 return _snd_ctl_register_ioctl(fcn, &snd_control_ioctls);
2079 EXPORT_SYMBOL(snd_ctl_register_ioctl);
2081 #ifdef CONFIG_COMPAT
2083 * snd_ctl_register_ioctl_compat - register the device-specific 32bit compat
2085 * @fcn: ioctl callback function
2087 * Return: zero if successful, or a negative error code
2089 int snd_ctl_register_ioctl_compat(snd_kctl_ioctl_func_t fcn)
2091 return _snd_ctl_register_ioctl(fcn, &snd_control_compat_ioctls);
2093 EXPORT_SYMBOL(snd_ctl_register_ioctl_compat);
2097 * de-register the device-specific control-ioctls.
2099 static int _snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn,
2100 struct list_head *lists)
2102 struct snd_kctl_ioctl *p;
2104 if (snd_BUG_ON(!fcn))
2106 guard(rwsem_write)(&snd_ioctl_rwsem);
2107 list_for_each_entry(p, lists, list) {
2108 if (p->fioctl == fcn) {
2119 * snd_ctl_unregister_ioctl - de-register the device-specific control-ioctls
2120 * @fcn: ioctl callback function to unregister
2122 * Return: zero if successful, or a negative error code
2124 int snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn)
2126 return _snd_ctl_unregister_ioctl(fcn, &snd_control_ioctls);
2128 EXPORT_SYMBOL(snd_ctl_unregister_ioctl);
2130 #ifdef CONFIG_COMPAT
2132 * snd_ctl_unregister_ioctl_compat - de-register the device-specific compat
2133 * 32bit control-ioctls
2134 * @fcn: ioctl callback function to unregister
2136 * Return: zero if successful, or a negative error code
2138 int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn)
2140 return _snd_ctl_unregister_ioctl(fcn, &snd_control_compat_ioctls);
2142 EXPORT_SYMBOL(snd_ctl_unregister_ioctl_compat);
2145 static int snd_ctl_fasync(int fd, struct file * file, int on)
2147 struct snd_ctl_file *ctl;
2149 ctl = file->private_data;
2150 return snd_fasync_helper(fd, file, on, &ctl->fasync);
2153 /* return the preferred subdevice number if already assigned;
2154 * otherwise return -1
2156 int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type)
2158 struct snd_ctl_file *kctl;
2161 guard(read_lock_irqsave)(&card->controls_rwlock);
2162 list_for_each_entry(kctl, &card->ctl_files, list) {
2163 if (kctl->pid == task_pid(current)) {
2164 subdevice = kctl->preferred_subdevice[type];
2165 if (subdevice != -1)
2171 EXPORT_SYMBOL_GPL(snd_ctl_get_preferred_subdevice);
2176 #ifdef CONFIG_COMPAT
2177 #include "control_compat.c"
2179 #define snd_ctl_ioctl_compat NULL
2183 * control layers (audio LED etc.)
2187 * snd_ctl_request_layer - request to use the layer
2188 * @module_name: Name of the kernel module (NULL == build-in)
2190 * Return: zero if successful, or an error code when the module cannot be loaded
2192 int snd_ctl_request_layer(const char *module_name)
2194 struct snd_ctl_layer_ops *lops;
2196 if (module_name == NULL)
2198 scoped_guard(rwsem_read, &snd_ctl_layer_rwsem) {
2199 for (lops = snd_ctl_layer; lops; lops = lops->next)
2200 if (strcmp(lops->module_name, module_name) == 0)
2203 return request_module(module_name);
2205 EXPORT_SYMBOL_GPL(snd_ctl_request_layer);
2208 * snd_ctl_register_layer - register new control layer
2209 * @lops: operation structure
2211 * The new layer can track all control elements and do additional
2212 * operations on top (like audio LED handling).
2214 void snd_ctl_register_layer(struct snd_ctl_layer_ops *lops)
2216 struct snd_card *card;
2219 scoped_guard(rwsem_write, &snd_ctl_layer_rwsem) {
2220 lops->next = snd_ctl_layer;
2221 snd_ctl_layer = lops;
2223 for (card_number = 0; card_number < SNDRV_CARDS; card_number++) {
2224 card = snd_card_ref(card_number);
2226 scoped_guard(rwsem_read, &card->controls_rwsem)
2227 lops->lregister(card);
2228 snd_card_unref(card);
2232 EXPORT_SYMBOL_GPL(snd_ctl_register_layer);
2235 * snd_ctl_disconnect_layer - disconnect control layer
2236 * @lops: operation structure
2238 * It is expected that the information about tracked cards
2239 * is freed before this call (the disconnect callback is
2242 void snd_ctl_disconnect_layer(struct snd_ctl_layer_ops *lops)
2244 struct snd_ctl_layer_ops *lops2, *prev_lops2;
2246 guard(rwsem_write)(&snd_ctl_layer_rwsem);
2247 for (lops2 = snd_ctl_layer, prev_lops2 = NULL; lops2; lops2 = lops2->next) {
2248 if (lops2 == lops) {
2250 snd_ctl_layer = lops->next;
2252 prev_lops2->next = lops->next;
2258 EXPORT_SYMBOL_GPL(snd_ctl_disconnect_layer);
2264 static const struct file_operations snd_ctl_f_ops =
2266 .owner = THIS_MODULE,
2267 .read = snd_ctl_read,
2268 .open = snd_ctl_open,
2269 .release = snd_ctl_release,
2270 .poll = snd_ctl_poll,
2271 .unlocked_ioctl = snd_ctl_ioctl,
2272 .compat_ioctl = snd_ctl_ioctl_compat,
2273 .fasync = snd_ctl_fasync,
2276 /* call lops under rwsems; called from snd_ctl_dev_*() below() */
2277 #define call_snd_ctl_lops(_card, _op) \
2279 struct snd_ctl_layer_ops *lops; \
2280 guard(rwsem_read)(&(_card)->controls_rwsem); \
2281 guard(rwsem_read)(&snd_ctl_layer_rwsem); \
2282 for (lops = snd_ctl_layer; lops; lops = lops->next) \
2287 * registration of the control device
2289 static int snd_ctl_dev_register(struct snd_device *device)
2291 struct snd_card *card = device->device_data;
2294 err = snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
2295 &snd_ctl_f_ops, card, card->ctl_dev);
2298 call_snd_ctl_lops(card, lregister);
2303 * disconnection of the control device
2305 static int snd_ctl_dev_disconnect(struct snd_device *device)
2307 struct snd_card *card = device->device_data;
2308 struct snd_ctl_file *ctl;
2310 scoped_guard(read_lock_irqsave, &card->controls_rwlock) {
2311 list_for_each_entry(ctl, &card->ctl_files, list) {
2312 wake_up(&ctl->change_sleep);
2313 snd_kill_fasync(ctl->fasync, SIGIO, POLL_ERR);
2317 call_snd_ctl_lops(card, ldisconnect);
2318 return snd_unregister_device(card->ctl_dev);
2324 static int snd_ctl_dev_free(struct snd_device *device)
2326 struct snd_card *card = device->device_data;
2327 struct snd_kcontrol *control;
2329 scoped_guard(rwsem_write, &card->controls_rwsem) {
2330 while (!list_empty(&card->controls)) {
2331 control = snd_kcontrol(card->controls.next);
2332 __snd_ctl_remove(card, control, false);
2335 #ifdef CONFIG_SND_CTL_FAST_LOOKUP
2336 xa_destroy(&card->ctl_numids);
2337 xa_destroy(&card->ctl_hash);
2340 put_device(card->ctl_dev);
2345 * create control core:
2346 * called from init.c
2348 int snd_ctl_create(struct snd_card *card)
2350 static const struct snd_device_ops ops = {
2351 .dev_free = snd_ctl_dev_free,
2352 .dev_register = snd_ctl_dev_register,
2353 .dev_disconnect = snd_ctl_dev_disconnect,
2357 if (snd_BUG_ON(!card))
2359 if (snd_BUG_ON(card->number < 0 || card->number >= SNDRV_CARDS))
2362 err = snd_device_alloc(&card->ctl_dev, card);
2365 dev_set_name(card->ctl_dev, "controlC%d", card->number);
2367 err = snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
2369 put_device(card->ctl_dev);
2374 * Frequently used control callbacks/helpers
2378 * snd_ctl_boolean_mono_info - Helper function for a standard boolean info
2379 * callback with a mono channel
2380 * @kcontrol: the kcontrol instance
2381 * @uinfo: info to store
2383 * This is a function that can be used as info callback for a standard
2384 * boolean control with a single mono channel.
2386 * Return: Zero (always successful)
2388 int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
2389 struct snd_ctl_elem_info *uinfo)
2391 uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
2393 uinfo->value.integer.min = 0;
2394 uinfo->value.integer.max = 1;
2397 EXPORT_SYMBOL(snd_ctl_boolean_mono_info);
2400 * snd_ctl_boolean_stereo_info - Helper function for a standard boolean info
2401 * callback with stereo two channels
2402 * @kcontrol: the kcontrol instance
2403 * @uinfo: info to store
2405 * This is a function that can be used as info callback for a standard
2406 * boolean control with stereo two channels.
2408 * Return: Zero (always successful)
2410 int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
2411 struct snd_ctl_elem_info *uinfo)
2413 uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
2415 uinfo->value.integer.min = 0;
2416 uinfo->value.integer.max = 1;
2419 EXPORT_SYMBOL(snd_ctl_boolean_stereo_info);
2422 * snd_ctl_enum_info - fills the info structure for an enumerated control
2423 * @info: the structure to be filled
2424 * @channels: the number of the control's channels; often one
2425 * @items: the number of control values; also the size of @names
2426 * @names: an array containing the names of all control values
2428 * Sets all required fields in @info to their appropriate values.
2429 * If the control's accessibility is not the default (readable and writable),
2430 * the caller has to fill @info->access.
2432 * Return: Zero (always successful)
2434 int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
2435 unsigned int items, const char *const names[])
2437 info->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
2438 info->count = channels;
2439 info->value.enumerated.items = items;
2442 if (info->value.enumerated.item >= items)
2443 info->value.enumerated.item = items - 1;
2444 WARN(strlen(names[info->value.enumerated.item]) >= sizeof(info->value.enumerated.name),
2445 "ALSA: too long item name '%s'\n",
2446 names[info->value.enumerated.item]);
2447 strscpy(info->value.enumerated.name,
2448 names[info->value.enumerated.item],
2449 sizeof(info->value.enumerated.name));
2452 EXPORT_SYMBOL(snd_ctl_enum_info);