2 * Routines for driver control interface
3 * Copyright (c) by Jaroslav Kysela <perex@perex.cz>
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.
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.
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
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>
33 /* max number of user-defined controls */
34 #define MAX_USER_CONTROLS 32
35 #define MAX_CONTROL_COUNT 1028
37 struct snd_kctl_ioctl {
38 struct list_head list; /* list of all ioctls */
39 snd_kctl_ioctl_func_t fioctl;
42 static DECLARE_RWSEM(snd_ioctl_rwsem);
43 static LIST_HEAD(snd_control_ioctls);
45 static LIST_HEAD(snd_control_compat_ioctls);
48 static int snd_ctl_open(struct inode *inode, struct file *file)
51 struct snd_card *card;
52 struct snd_ctl_file *ctl;
55 err = nonseekable_open(inode, file);
59 card = snd_lookup_minor_data(iminor(inode), SNDRV_DEVICE_TYPE_CONTROL);
64 err = snd_card_file_add(card, file);
69 if (!try_module_get(card->module)) {
73 ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);
78 INIT_LIST_HEAD(&ctl->events);
79 init_waitqueue_head(&ctl->change_sleep);
80 spin_lock_init(&ctl->read_lock);
82 ctl->prefer_pcm_subdevice = -1;
83 ctl->prefer_rawmidi_subdevice = -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);
93 module_put(card->module);
95 snd_card_file_remove(card, file);
102 static void snd_ctl_empty_read_queue(struct snd_ctl_file * ctl)
105 struct snd_kctl_event *cread;
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);
113 spin_unlock_irqrestore(&ctl->read_lock, flags);
116 static int snd_ctl_release(struct inode *inode, struct file *file)
119 struct snd_card *card;
120 struct snd_ctl_file *ctl;
121 struct snd_kcontrol *control;
124 ctl = file->private_data;
125 file->private_data = NULL;
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);
139 module_put(card->module);
140 snd_card_file_remove(card, file);
144 void snd_ctl_notify(struct snd_card *card, unsigned int mask,
145 struct snd_ctl_elem_id *id)
148 struct snd_ctl_file *ctl;
149 struct snd_kctl_event *ev;
151 if (snd_BUG_ON(!card || !id))
153 read_lock(&card->ctl_files_rwlock);
154 #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
155 card->mixer_oss_change_count++;
157 list_for_each_entry(ctl, &card->ctl_files, list) {
158 if (!ctl->subscribed)
160 spin_lock_irqsave(&ctl->read_lock, flags);
161 list_for_each_entry(ev, &ctl->events, list) {
162 if (ev->id.numid == id->numid) {
167 ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
171 list_add_tail(&ev->list, &ctl->events);
173 snd_printk(KERN_ERR "No memory available to allocate event\n");
176 wake_up(&ctl->change_sleep);
177 spin_unlock_irqrestore(&ctl->read_lock, flags);
178 kill_fasync(&ctl->fasync, SIGIO, POLL_IN);
180 read_unlock(&card->ctl_files_rwlock);
183 EXPORT_SYMBOL(snd_ctl_notify);
186 * snd_ctl_new - create a control instance from the template
187 * @control: the control template
188 * @access: the default control access
190 * Allocates a new struct snd_kcontrol instance and copies the given template
191 * to the new instance. It does not copy volatile data (access).
193 * Returns the pointer of the new instance, or NULL on failure.
195 static struct snd_kcontrol *snd_ctl_new(struct snd_kcontrol *control,
198 struct snd_kcontrol *kctl;
201 if (snd_BUG_ON(!control || !control->count))
204 if (control->count > MAX_CONTROL_COUNT)
207 kctl = kzalloc(sizeof(*kctl) + sizeof(struct snd_kcontrol_volatile) * control->count, GFP_KERNEL);
209 snd_printk(KERN_ERR "Cannot allocate control instance\n");
213 for (idx = 0; idx < kctl->count; idx++)
214 kctl->vd[idx].access = access;
219 * snd_ctl_new1 - create a control instance from the template
220 * @ncontrol: the initialization record
221 * @private_data: the private data to set
223 * Allocates a new struct snd_kcontrol instance and initialize from the given
224 * template. When the access field of ncontrol is 0, it's assumed as
225 * READWRITE access. When the count field is 0, it's assumes as one.
227 * Returns the pointer of the newly generated instance, or NULL on failure.
229 struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new *ncontrol,
232 struct snd_kcontrol kctl;
235 if (snd_BUG_ON(!ncontrol || !ncontrol->info))
237 memset(&kctl, 0, sizeof(kctl));
238 kctl.id.iface = ncontrol->iface;
239 kctl.id.device = ncontrol->device;
240 kctl.id.subdevice = ncontrol->subdevice;
241 if (ncontrol->name) {
242 strlcpy(kctl.id.name, ncontrol->name, sizeof(kctl.id.name));
243 if (strcmp(ncontrol->name, kctl.id.name) != 0)
244 snd_printk(KERN_WARNING
245 "Control name '%s' truncated to '%s'\n",
246 ncontrol->name, kctl.id.name);
248 kctl.id.index = ncontrol->index;
249 kctl.count = ncontrol->count ? ncontrol->count : 1;
250 access = ncontrol->access == 0 ? SNDRV_CTL_ELEM_ACCESS_READWRITE :
251 (ncontrol->access & (SNDRV_CTL_ELEM_ACCESS_READWRITE|
252 SNDRV_CTL_ELEM_ACCESS_INACTIVE|
253 SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE|
254 SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND|
255 SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK));
256 kctl.info = ncontrol->info;
257 kctl.get = ncontrol->get;
258 kctl.put = ncontrol->put;
259 kctl.tlv.p = ncontrol->tlv.p;
260 kctl.private_value = ncontrol->private_value;
261 kctl.private_data = private_data;
262 return snd_ctl_new(&kctl, access);
265 EXPORT_SYMBOL(snd_ctl_new1);
268 * snd_ctl_free_one - release the control instance
269 * @kcontrol: the control instance
271 * Releases the control instance created via snd_ctl_new()
273 * Don't call this after the control was added to the card.
275 void snd_ctl_free_one(struct snd_kcontrol *kcontrol)
278 if (kcontrol->private_free)
279 kcontrol->private_free(kcontrol);
284 EXPORT_SYMBOL(snd_ctl_free_one);
286 static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
289 struct snd_kcontrol *kctl;
291 list_for_each_entry(kctl, &card->controls, list) {
292 if (kctl->id.numid < card->last_numid + 1 + count &&
293 kctl->id.numid + kctl->count > card->last_numid + 1) {
294 card->last_numid = kctl->id.numid + kctl->count - 1;
301 static int snd_ctl_find_hole(struct snd_card *card, unsigned int count)
303 unsigned int iter = 100000;
305 while (snd_ctl_remove_numid_conflict(card, count)) {
307 /* this situation is very unlikely */
308 snd_printk(KERN_ERR "unable to allocate new control numid\n");
316 * snd_ctl_add - add the control instance to the card
317 * @card: the card instance
318 * @kcontrol: the control instance to add
320 * Adds the control instance created via snd_ctl_new() or
321 * snd_ctl_new1() to the given card. Assigns also an unique
322 * numid used for fast search.
324 * Returns zero if successful, or a negative error code on failure.
326 * It frees automatically the control which cannot be added.
328 int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
330 struct snd_ctl_elem_id id;
336 if (snd_BUG_ON(!card || !kcontrol->info))
339 down_write(&card->controls_rwsem);
340 if (snd_ctl_find_id(card, &id)) {
341 up_write(&card->controls_rwsem);
342 snd_printd(KERN_ERR "control %i:%i:%i:%s:%i is already present\n",
351 if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
352 up_write(&card->controls_rwsem);
356 list_add_tail(&kcontrol->list, &card->controls);
357 card->controls_count += kcontrol->count;
358 kcontrol->id.numid = card->last_numid + 1;
359 card->last_numid += kcontrol->count;
360 up_write(&card->controls_rwsem);
361 for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
362 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
366 snd_ctl_free_one(kcontrol);
370 EXPORT_SYMBOL(snd_ctl_add);
373 * snd_ctl_replace - replace the control instance of the card
374 * @card: the card instance
375 * @kcontrol: the control instance to replace
376 * @add_on_replace: add the control if not already added
378 * Replaces the given control. If the given control does not exist
379 * and the add_on_replace flag is set, the control is added. If the
380 * control exists, it is destroyed first.
382 * Returns zero if successful, or a negative error code on failure.
384 * It frees automatically the control which cannot be added or replaced.
386 int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
389 struct snd_ctl_elem_id id;
391 struct snd_kcontrol *old;
396 if (snd_BUG_ON(!card || !kcontrol->info)) {
401 down_write(&card->controls_rwsem);
402 old = snd_ctl_find_id(card, &id);
406 up_write(&card->controls_rwsem);
410 ret = snd_ctl_remove(card, old);
412 up_write(&card->controls_rwsem);
416 if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
417 up_write(&card->controls_rwsem);
421 list_add_tail(&kcontrol->list, &card->controls);
422 card->controls_count += kcontrol->count;
423 kcontrol->id.numid = card->last_numid + 1;
424 card->last_numid += kcontrol->count;
425 up_write(&card->controls_rwsem);
426 for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
427 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
431 snd_ctl_free_one(kcontrol);
434 EXPORT_SYMBOL(snd_ctl_replace);
437 * snd_ctl_remove - remove the control from the card and release it
438 * @card: the card instance
439 * @kcontrol: the control instance to remove
441 * Removes the control from the card and then releases the instance.
442 * You don't need to call snd_ctl_free_one(). You must be in
443 * the write lock - down_write(&card->controls_rwsem).
445 * Returns 0 if successful, or a negative error code on failure.
447 int snd_ctl_remove(struct snd_card *card, struct snd_kcontrol *kcontrol)
449 struct snd_ctl_elem_id id;
452 if (snd_BUG_ON(!card || !kcontrol))
454 list_del(&kcontrol->list);
455 card->controls_count -= kcontrol->count;
457 for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
458 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_REMOVE, &id);
459 snd_ctl_free_one(kcontrol);
463 EXPORT_SYMBOL(snd_ctl_remove);
466 * snd_ctl_remove_id - remove the control of the given id and release it
467 * @card: the card instance
468 * @id: the control id to remove
470 * Finds the control instance with the given id, removes it from the
471 * card list and releases it.
473 * Returns 0 if successful, or a negative error code on failure.
475 int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)
477 struct snd_kcontrol *kctl;
480 down_write(&card->controls_rwsem);
481 kctl = snd_ctl_find_id(card, id);
483 up_write(&card->controls_rwsem);
486 ret = snd_ctl_remove(card, kctl);
487 up_write(&card->controls_rwsem);
491 EXPORT_SYMBOL(snd_ctl_remove_id);
494 * snd_ctl_remove_user_ctl - remove and release the unlocked user control
495 * @file: active control handle
496 * @id: the control id to remove
498 * Finds the control instance with the given id, removes it from the
499 * card list and releases it.
501 * Returns 0 if successful, or a negative error code on failure.
503 static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
504 struct snd_ctl_elem_id *id)
506 struct snd_card *card = file->card;
507 struct snd_kcontrol *kctl;
510 down_write(&card->controls_rwsem);
511 kctl = snd_ctl_find_id(card, id);
516 if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER)) {
520 for (idx = 0; idx < kctl->count; idx++)
521 if (kctl->vd[idx].owner != NULL && kctl->vd[idx].owner != file) {
525 ret = snd_ctl_remove(card, kctl);
528 card->user_ctl_count--;
530 up_write(&card->controls_rwsem);
535 * snd_ctl_activate_id - activate/inactivate the control of the given id
536 * @card: the card instance
537 * @id: the control id to activate/inactivate
538 * @active: non-zero to activate
540 * Finds the control instance with the given id, and activate or
541 * inactivate the control together with notification, if changed.
543 * Returns 0 if unchanged, 1 if changed, or a negative error code on failure.
545 int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
548 struct snd_kcontrol *kctl;
549 struct snd_kcontrol_volatile *vd;
550 unsigned int index_offset;
553 down_write(&card->controls_rwsem);
554 kctl = snd_ctl_find_id(card, id);
559 index_offset = snd_ctl_get_ioff(kctl, &kctl->id);
560 vd = &kctl->vd[index_offset];
563 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
565 vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
567 if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
569 vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
573 up_write(&card->controls_rwsem);
575 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, id);
578 EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
581 * snd_ctl_rename_id - replace the id of a control on the card
582 * @card: the card instance
583 * @src_id: the old id
584 * @dst_id: the new id
586 * Finds the control with the old id from the card, and replaces the
587 * id with the new one.
589 * Returns zero if successful, or a negative error code on failure.
591 int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
592 struct snd_ctl_elem_id *dst_id)
594 struct snd_kcontrol *kctl;
596 down_write(&card->controls_rwsem);
597 kctl = snd_ctl_find_id(card, src_id);
599 up_write(&card->controls_rwsem);
603 kctl->id.numid = card->last_numid + 1;
604 card->last_numid += kctl->count;
605 up_write(&card->controls_rwsem);
609 EXPORT_SYMBOL(snd_ctl_rename_id);
612 * snd_ctl_find_numid - find the control instance with the given number-id
613 * @card: the card instance
614 * @numid: the number-id to search
616 * Finds the control instance with the given number-id from the card.
618 * Returns the pointer of the instance if found, or NULL if not.
620 * The caller must down card->controls_rwsem before calling this function
621 * (if the race condition can happen).
623 struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card, unsigned int numid)
625 struct snd_kcontrol *kctl;
627 if (snd_BUG_ON(!card || !numid))
629 list_for_each_entry(kctl, &card->controls, list) {
630 if (kctl->id.numid <= numid && kctl->id.numid + kctl->count > numid)
636 EXPORT_SYMBOL(snd_ctl_find_numid);
639 * snd_ctl_find_id - find the control instance with the given id
640 * @card: the card instance
641 * @id: the id to search
643 * Finds the control instance with the given id from the card.
645 * Returns the pointer of the instance if found, or NULL if not.
647 * The caller must down card->controls_rwsem before calling this function
648 * (if the race condition can happen).
650 struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
651 struct snd_ctl_elem_id *id)
653 struct snd_kcontrol *kctl;
655 if (snd_BUG_ON(!card || !id))
658 return snd_ctl_find_numid(card, id->numid);
659 list_for_each_entry(kctl, &card->controls, list) {
660 if (kctl->id.iface != id->iface)
662 if (kctl->id.device != id->device)
664 if (kctl->id.subdevice != id->subdevice)
666 if (strncmp(kctl->id.name, id->name, sizeof(kctl->id.name)))
668 if (kctl->id.index > id->index)
670 if (kctl->id.index + kctl->count <= id->index)
677 EXPORT_SYMBOL(snd_ctl_find_id);
679 static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,
680 unsigned int cmd, void __user *arg)
682 struct snd_ctl_card_info *info;
684 info = kzalloc(sizeof(*info), GFP_KERNEL);
687 down_read(&snd_ioctl_rwsem);
688 info->card = card->number;
689 strlcpy(info->id, card->id, sizeof(info->id));
690 strlcpy(info->driver, card->driver, sizeof(info->driver));
691 strlcpy(info->name, card->shortname, sizeof(info->name));
692 strlcpy(info->longname, card->longname, sizeof(info->longname));
693 strlcpy(info->mixername, card->mixername, sizeof(info->mixername));
694 strlcpy(info->components, card->components, sizeof(info->components));
695 up_read(&snd_ioctl_rwsem);
696 if (copy_to_user(arg, info, sizeof(struct snd_ctl_card_info))) {
704 static int snd_ctl_elem_list(struct snd_card *card,
705 struct snd_ctl_elem_list __user *_list)
707 struct list_head *plist;
708 struct snd_ctl_elem_list list;
709 struct snd_kcontrol *kctl;
710 struct snd_ctl_elem_id *dst, *id;
711 unsigned int offset, space, jidx;
713 if (copy_from_user(&list, _list, sizeof(list)))
715 offset = list.offset;
717 /* try limit maximum space */
721 /* allocate temporary buffer for atomic operation */
722 dst = vmalloc(space * sizeof(struct snd_ctl_elem_id));
725 down_read(&card->controls_rwsem);
726 list.count = card->controls_count;
727 plist = card->controls.next;
728 while (plist != &card->controls) {
731 kctl = snd_kcontrol(plist);
732 if (offset < kctl->count)
734 offset -= kctl->count;
739 while (space > 0 && plist != &card->controls) {
740 kctl = snd_kcontrol(plist);
741 for (jidx = offset; space > 0 && jidx < kctl->count; jidx++) {
742 snd_ctl_build_ioff(id, kctl, jidx);
750 up_read(&card->controls_rwsem);
752 copy_to_user(list.pids, dst,
753 list.used * sizeof(struct snd_ctl_elem_id))) {
759 down_read(&card->controls_rwsem);
760 list.count = card->controls_count;
761 up_read(&card->controls_rwsem);
763 if (copy_to_user(_list, &list, sizeof(list)))
768 static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
769 struct snd_ctl_elem_info *info)
771 struct snd_card *card = ctl->card;
772 struct snd_kcontrol *kctl;
773 struct snd_kcontrol_volatile *vd;
774 unsigned int index_offset;
777 down_read(&card->controls_rwsem);
778 kctl = snd_ctl_find_id(card, &info->id);
780 up_read(&card->controls_rwsem);
783 #ifdef CONFIG_SND_DEBUG
786 result = kctl->info(kctl, info);
788 snd_BUG_ON(info->access);
789 index_offset = snd_ctl_get_ioff(kctl, &info->id);
790 vd = &kctl->vd[index_offset];
791 snd_ctl_build_ioff(&info->id, kctl, index_offset);
792 info->access = vd->access;
794 info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
795 if (vd->owner == ctl)
796 info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;
797 info->owner = pid_vnr(vd->owner->pid);
802 up_read(&card->controls_rwsem);
806 static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
807 struct snd_ctl_elem_info __user *_info)
809 struct snd_ctl_elem_info info;
812 if (copy_from_user(&info, _info, sizeof(info)))
814 snd_power_lock(ctl->card);
815 result = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);
817 result = snd_ctl_elem_info(ctl, &info);
818 snd_power_unlock(ctl->card);
820 if (copy_to_user(_info, &info, sizeof(info)))
825 static int snd_ctl_elem_read(struct snd_card *card,
826 struct snd_ctl_elem_value *control)
828 struct snd_kcontrol *kctl;
829 struct snd_kcontrol_volatile *vd;
830 unsigned int index_offset;
833 down_read(&card->controls_rwsem);
834 kctl = snd_ctl_find_id(card, &control->id);
838 index_offset = snd_ctl_get_ioff(kctl, &control->id);
839 vd = &kctl->vd[index_offset];
840 if ((vd->access & SNDRV_CTL_ELEM_ACCESS_READ) &&
842 snd_ctl_build_ioff(&control->id, kctl, index_offset);
843 result = kctl->get(kctl, control);
847 up_read(&card->controls_rwsem);
851 static int snd_ctl_elem_read_user(struct snd_card *card,
852 struct snd_ctl_elem_value __user *_control)
854 struct snd_ctl_elem_value *control;
857 control = memdup_user(_control, sizeof(*control));
859 return PTR_ERR(control);
861 snd_power_lock(card);
862 result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
864 result = snd_ctl_elem_read(card, control);
865 snd_power_unlock(card);
867 if (copy_to_user(_control, control, sizeof(*control)))
873 static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
874 struct snd_ctl_elem_value *control)
876 struct snd_kcontrol *kctl;
877 struct snd_kcontrol_volatile *vd;
878 unsigned int index_offset;
881 down_read(&card->controls_rwsem);
882 kctl = snd_ctl_find_id(card, &control->id);
886 index_offset = snd_ctl_get_ioff(kctl, &control->id);
887 vd = &kctl->vd[index_offset];
888 if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_WRITE) ||
890 (file && vd->owner && vd->owner != file)) {
893 snd_ctl_build_ioff(&control->id, kctl, index_offset);
894 result = kctl->put(kctl, control);
897 up_read(&card->controls_rwsem);
898 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
903 up_read(&card->controls_rwsem);
907 static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
908 struct snd_ctl_elem_value __user *_control)
910 struct snd_ctl_elem_value *control;
911 struct snd_card *card;
914 control = memdup_user(_control, sizeof(*control));
916 return PTR_ERR(control);
919 snd_power_lock(card);
920 result = snd_power_wait(card, SNDRV_CTL_POWER_D0);
922 result = snd_ctl_elem_write(card, file, control);
923 snd_power_unlock(card);
925 if (copy_to_user(_control, control, sizeof(*control)))
931 static int snd_ctl_elem_lock(struct snd_ctl_file *file,
932 struct snd_ctl_elem_id __user *_id)
934 struct snd_card *card = file->card;
935 struct snd_ctl_elem_id id;
936 struct snd_kcontrol *kctl;
937 struct snd_kcontrol_volatile *vd;
940 if (copy_from_user(&id, _id, sizeof(id)))
942 down_write(&card->controls_rwsem);
943 kctl = snd_ctl_find_id(card, &id);
947 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
948 if (vd->owner != NULL)
955 up_write(&card->controls_rwsem);
959 static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
960 struct snd_ctl_elem_id __user *_id)
962 struct snd_card *card = file->card;
963 struct snd_ctl_elem_id id;
964 struct snd_kcontrol *kctl;
965 struct snd_kcontrol_volatile *vd;
968 if (copy_from_user(&id, _id, sizeof(id)))
970 down_write(&card->controls_rwsem);
971 kctl = snd_ctl_find_id(card, &id);
975 vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
976 if (vd->owner == NULL)
978 else if (vd->owner != file)
985 up_write(&card->controls_rwsem);
989 struct user_element {
990 struct snd_ctl_elem_info info;
991 struct snd_card *card;
992 void *elem_data; /* element data */
993 unsigned long elem_data_size; /* size of element data in bytes */
994 void *tlv_data; /* TLV data */
995 unsigned long tlv_data_size; /* TLV data size */
996 void *priv_data; /* private data (like strings for enumerated type) */
999 static int snd_ctl_elem_user_info(struct snd_kcontrol *kcontrol,
1000 struct snd_ctl_elem_info *uinfo)
1002 struct user_element *ue = kcontrol->private_data;
1008 static int snd_ctl_elem_user_enum_info(struct snd_kcontrol *kcontrol,
1009 struct snd_ctl_elem_info *uinfo)
1011 struct user_element *ue = kcontrol->private_data;
1015 item = uinfo->value.enumerated.item;
1019 item = min(item, uinfo->value.enumerated.items - 1);
1020 uinfo->value.enumerated.item = item;
1022 names = ue->priv_data;
1023 for (; item > 0; --item)
1024 names += strlen(names) + 1;
1025 strcpy(uinfo->value.enumerated.name, names);
1030 static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
1031 struct snd_ctl_elem_value *ucontrol)
1033 struct user_element *ue = kcontrol->private_data;
1035 mutex_lock(&ue->card->user_ctl_lock);
1036 memcpy(&ucontrol->value, ue->elem_data, ue->elem_data_size);
1037 mutex_unlock(&ue->card->user_ctl_lock);
1041 static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
1042 struct snd_ctl_elem_value *ucontrol)
1045 struct user_element *ue = kcontrol->private_data;
1047 mutex_lock(&ue->card->user_ctl_lock);
1048 change = memcmp(&ucontrol->value, ue->elem_data, ue->elem_data_size) != 0;
1050 memcpy(ue->elem_data, &ucontrol->value, ue->elem_data_size);
1051 mutex_unlock(&ue->card->user_ctl_lock);
1055 static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol,
1058 unsigned int __user *tlv)
1060 struct user_element *ue = kcontrol->private_data;
1065 if (size > 1024 * 128) /* sane value */
1068 new_data = memdup_user(tlv, size);
1069 if (IS_ERR(new_data))
1070 return PTR_ERR(new_data);
1071 mutex_lock(&ue->card->user_ctl_lock);
1072 change = ue->tlv_data_size != size;
1074 change = memcmp(ue->tlv_data, new_data, size);
1075 kfree(ue->tlv_data);
1076 ue->tlv_data = new_data;
1077 ue->tlv_data_size = size;
1078 mutex_unlock(&ue->card->user_ctl_lock);
1082 mutex_lock(&ue->card->user_ctl_lock);
1083 if (!ue->tlv_data_size || !ue->tlv_data) {
1087 if (size < ue->tlv_data_size) {
1091 if (copy_to_user(tlv, ue->tlv_data, ue->tlv_data_size))
1094 mutex_unlock(&ue->card->user_ctl_lock);
1101 static int snd_ctl_elem_init_enum_names(struct user_element *ue)
1104 size_t buf_len, name_len;
1106 const uintptr_t user_ptrval = ue->info.value.enumerated.names_ptr;
1108 if (ue->info.value.enumerated.names_length > 64 * 1024)
1111 names = memdup_user((const void __user *)user_ptrval,
1112 ue->info.value.enumerated.names_length);
1114 return PTR_ERR(names);
1116 /* check that there are enough valid names */
1117 buf_len = ue->info.value.enumerated.names_length;
1119 for (i = 0; i < ue->info.value.enumerated.items; ++i) {
1120 name_len = strnlen(p, buf_len);
1121 if (name_len == 0 || name_len >= 64 || name_len == buf_len) {
1126 buf_len -= name_len + 1;
1129 ue->priv_data = names;
1130 ue->info.value.enumerated.names_ptr = 0;
1135 static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)
1137 struct user_element *ue = kcontrol->private_data;
1139 kfree(ue->tlv_data);
1140 kfree(ue->priv_data);
1144 static int snd_ctl_elem_add(struct snd_ctl_file *file,
1145 struct snd_ctl_elem_info *info, int replace)
1147 struct snd_card *card = file->card;
1148 struct snd_kcontrol kctl, *_kctl;
1149 unsigned int access;
1151 struct user_element *ue;
1154 if (info->count < 1)
1156 access = info->access == 0 ? SNDRV_CTL_ELEM_ACCESS_READWRITE :
1157 (info->access & (SNDRV_CTL_ELEM_ACCESS_READWRITE|
1158 SNDRV_CTL_ELEM_ACCESS_INACTIVE|
1159 SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE));
1161 memset(&kctl, 0, sizeof(kctl));
1164 err = snd_ctl_remove_user_ctl(file, &info->id);
1169 if (card->user_ctl_count >= MAX_USER_CONTROLS)
1172 memcpy(&kctl.id, &info->id, sizeof(info->id));
1173 kctl.count = info->owner ? info->owner : 1;
1174 access |= SNDRV_CTL_ELEM_ACCESS_USER;
1175 if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
1176 kctl.info = snd_ctl_elem_user_enum_info;
1178 kctl.info = snd_ctl_elem_user_info;
1179 if (access & SNDRV_CTL_ELEM_ACCESS_READ)
1180 kctl.get = snd_ctl_elem_user_get;
1181 if (access & SNDRV_CTL_ELEM_ACCESS_WRITE)
1182 kctl.put = snd_ctl_elem_user_put;
1183 if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE) {
1184 kctl.tlv.c = snd_ctl_elem_user_tlv;
1185 access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
1187 switch (info->type) {
1188 case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
1189 case SNDRV_CTL_ELEM_TYPE_INTEGER:
1190 private_size = sizeof(long);
1191 if (info->count > 128)
1194 case SNDRV_CTL_ELEM_TYPE_INTEGER64:
1195 private_size = sizeof(long long);
1196 if (info->count > 64)
1199 case SNDRV_CTL_ELEM_TYPE_ENUMERATED:
1200 private_size = sizeof(unsigned int);
1201 if (info->count > 128 || info->value.enumerated.items == 0)
1204 case SNDRV_CTL_ELEM_TYPE_BYTES:
1205 private_size = sizeof(unsigned char);
1206 if (info->count > 512)
1209 case SNDRV_CTL_ELEM_TYPE_IEC958:
1210 private_size = sizeof(struct snd_aes_iec958);
1211 if (info->count != 1)
1217 private_size *= info->count;
1218 ue = kzalloc(sizeof(struct user_element) + private_size, GFP_KERNEL);
1223 ue->info.access = 0;
1224 ue->elem_data = (char *)ue + sizeof(*ue);
1225 ue->elem_data_size = private_size;
1226 if (ue->info.type == SNDRV_CTL_ELEM_TYPE_ENUMERATED) {
1227 err = snd_ctl_elem_init_enum_names(ue);
1233 kctl.private_free = snd_ctl_elem_user_free;
1234 _kctl = snd_ctl_new(&kctl, access);
1235 if (_kctl == NULL) {
1236 kfree(ue->priv_data);
1240 _kctl->private_data = ue;
1241 for (idx = 0; idx < _kctl->count; idx++)
1242 _kctl->vd[idx].owner = file;
1243 err = snd_ctl_add(card, _kctl);
1247 down_write(&card->controls_rwsem);
1248 card->user_ctl_count++;
1249 up_write(&card->controls_rwsem);
1254 static int snd_ctl_elem_add_user(struct snd_ctl_file *file,
1255 struct snd_ctl_elem_info __user *_info, int replace)
1257 struct snd_ctl_elem_info info;
1258 if (copy_from_user(&info, _info, sizeof(info)))
1260 return snd_ctl_elem_add(file, &info, replace);
1263 static int snd_ctl_elem_remove(struct snd_ctl_file *file,
1264 struct snd_ctl_elem_id __user *_id)
1266 struct snd_ctl_elem_id id;
1268 if (copy_from_user(&id, _id, sizeof(id)))
1270 return snd_ctl_remove_user_ctl(file, &id);
1273 static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
1276 if (get_user(subscribe, ptr))
1278 if (subscribe < 0) {
1279 subscribe = file->subscribed;
1280 if (put_user(subscribe, ptr))
1285 file->subscribed = 1;
1287 } else if (file->subscribed) {
1288 snd_ctl_empty_read_queue(file);
1289 file->subscribed = 0;
1294 static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
1295 struct snd_ctl_tlv __user *_tlv,
1298 struct snd_card *card = file->card;
1299 struct snd_ctl_tlv tlv;
1300 struct snd_kcontrol *kctl;
1301 struct snd_kcontrol_volatile *vd;
1305 if (copy_from_user(&tlv, _tlv, sizeof(tlv)))
1307 if (tlv.length < sizeof(unsigned int) * 2)
1309 down_read(&card->controls_rwsem);
1310 kctl = snd_ctl_find_numid(card, tlv.numid);
1315 if (kctl->tlv.p == NULL) {
1319 vd = &kctl->vd[tlv.numid - kctl->id.numid];
1320 if ((op_flag == 0 && (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ) == 0) ||
1321 (op_flag > 0 && (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE) == 0) ||
1322 (op_flag < 0 && (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND) == 0)) {
1326 if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
1327 if (vd->owner != NULL && vd->owner != file) {
1331 err = kctl->tlv.c(kctl, op_flag, tlv.length, _tlv->tlv);
1333 up_read(&card->controls_rwsem);
1334 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_TLV, &kctl->id);
1342 len = kctl->tlv.p[1] + 2 * sizeof(unsigned int);
1343 if (tlv.length < len) {
1347 if (copy_to_user(_tlv->tlv, kctl->tlv.p, len))
1351 up_read(&card->controls_rwsem);
1355 static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1357 struct snd_ctl_file *ctl;
1358 struct snd_card *card;
1359 struct snd_kctl_ioctl *p;
1360 void __user *argp = (void __user *)arg;
1361 int __user *ip = argp;
1364 ctl = file->private_data;
1366 if (snd_BUG_ON(!card))
1369 case SNDRV_CTL_IOCTL_PVERSION:
1370 return put_user(SNDRV_CTL_VERSION, ip) ? -EFAULT : 0;
1371 case SNDRV_CTL_IOCTL_CARD_INFO:
1372 return snd_ctl_card_info(card, ctl, cmd, argp);
1373 case SNDRV_CTL_IOCTL_ELEM_LIST:
1374 return snd_ctl_elem_list(card, argp);
1375 case SNDRV_CTL_IOCTL_ELEM_INFO:
1376 return snd_ctl_elem_info_user(ctl, argp);
1377 case SNDRV_CTL_IOCTL_ELEM_READ:
1378 return snd_ctl_elem_read_user(card, argp);
1379 case SNDRV_CTL_IOCTL_ELEM_WRITE:
1380 return snd_ctl_elem_write_user(ctl, argp);
1381 case SNDRV_CTL_IOCTL_ELEM_LOCK:
1382 return snd_ctl_elem_lock(ctl, argp);
1383 case SNDRV_CTL_IOCTL_ELEM_UNLOCK:
1384 return snd_ctl_elem_unlock(ctl, argp);
1385 case SNDRV_CTL_IOCTL_ELEM_ADD:
1386 return snd_ctl_elem_add_user(ctl, argp, 0);
1387 case SNDRV_CTL_IOCTL_ELEM_REPLACE:
1388 return snd_ctl_elem_add_user(ctl, argp, 1);
1389 case SNDRV_CTL_IOCTL_ELEM_REMOVE:
1390 return snd_ctl_elem_remove(ctl, argp);
1391 case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
1392 return snd_ctl_subscribe_events(ctl, ip);
1393 case SNDRV_CTL_IOCTL_TLV_READ:
1394 return snd_ctl_tlv_ioctl(ctl, argp, 0);
1395 case SNDRV_CTL_IOCTL_TLV_WRITE:
1396 return snd_ctl_tlv_ioctl(ctl, argp, 1);
1397 case SNDRV_CTL_IOCTL_TLV_COMMAND:
1398 return snd_ctl_tlv_ioctl(ctl, argp, -1);
1399 case SNDRV_CTL_IOCTL_POWER:
1400 return -ENOPROTOOPT;
1401 case SNDRV_CTL_IOCTL_POWER_STATE:
1403 return put_user(card->power_state, ip) ? -EFAULT : 0;
1405 return put_user(SNDRV_CTL_POWER_D0, ip) ? -EFAULT : 0;
1408 down_read(&snd_ioctl_rwsem);
1409 list_for_each_entry(p, &snd_control_ioctls, list) {
1410 err = p->fioctl(card, ctl, cmd, arg);
1411 if (err != -ENOIOCTLCMD) {
1412 up_read(&snd_ioctl_rwsem);
1416 up_read(&snd_ioctl_rwsem);
1417 snd_printdd("unknown ioctl = 0x%x\n", cmd);
1421 static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
1422 size_t count, loff_t * offset)
1424 struct snd_ctl_file *ctl;
1428 ctl = file->private_data;
1429 if (snd_BUG_ON(!ctl || !ctl->card))
1431 if (!ctl->subscribed)
1433 if (count < sizeof(struct snd_ctl_event))
1435 spin_lock_irq(&ctl->read_lock);
1436 while (count >= sizeof(struct snd_ctl_event)) {
1437 struct snd_ctl_event ev;
1438 struct snd_kctl_event *kev;
1439 while (list_empty(&ctl->events)) {
1441 if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
1445 init_waitqueue_entry(&wait, current);
1446 add_wait_queue(&ctl->change_sleep, &wait);
1447 set_current_state(TASK_INTERRUPTIBLE);
1448 spin_unlock_irq(&ctl->read_lock);
1450 remove_wait_queue(&ctl->change_sleep, &wait);
1451 if (ctl->card->shutdown)
1453 if (signal_pending(current))
1454 return -ERESTARTSYS;
1455 spin_lock_irq(&ctl->read_lock);
1457 kev = snd_kctl_event(ctl->events.next);
1458 ev.type = SNDRV_CTL_EVENT_ELEM;
1459 ev.data.elem.mask = kev->mask;
1460 ev.data.elem.id = kev->id;
1461 list_del(&kev->list);
1462 spin_unlock_irq(&ctl->read_lock);
1464 if (copy_to_user(buffer, &ev, sizeof(struct snd_ctl_event))) {
1468 spin_lock_irq(&ctl->read_lock);
1469 buffer += sizeof(struct snd_ctl_event);
1470 count -= sizeof(struct snd_ctl_event);
1471 result += sizeof(struct snd_ctl_event);
1474 spin_unlock_irq(&ctl->read_lock);
1476 return result > 0 ? result : err;
1479 static unsigned int snd_ctl_poll(struct file *file, poll_table * wait)
1482 struct snd_ctl_file *ctl;
1484 ctl = file->private_data;
1485 if (!ctl->subscribed)
1487 poll_wait(file, &ctl->change_sleep, wait);
1490 if (!list_empty(&ctl->events))
1491 mask |= POLLIN | POLLRDNORM;
1497 * register the device-specific control-ioctls.
1498 * called from each device manager like pcm.c, hwdep.c, etc.
1500 static int _snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn, struct list_head *lists)
1502 struct snd_kctl_ioctl *pn;
1504 pn = kzalloc(sizeof(struct snd_kctl_ioctl), GFP_KERNEL);
1508 down_write(&snd_ioctl_rwsem);
1509 list_add_tail(&pn->list, lists);
1510 up_write(&snd_ioctl_rwsem);
1514 int snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn)
1516 return _snd_ctl_register_ioctl(fcn, &snd_control_ioctls);
1519 EXPORT_SYMBOL(snd_ctl_register_ioctl);
1521 #ifdef CONFIG_COMPAT
1522 int snd_ctl_register_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1524 return _snd_ctl_register_ioctl(fcn, &snd_control_compat_ioctls);
1527 EXPORT_SYMBOL(snd_ctl_register_ioctl_compat);
1531 * de-register the device-specific control-ioctls.
1533 static int _snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn,
1534 struct list_head *lists)
1536 struct snd_kctl_ioctl *p;
1538 if (snd_BUG_ON(!fcn))
1540 down_write(&snd_ioctl_rwsem);
1541 list_for_each_entry(p, lists, list) {
1542 if (p->fioctl == fcn) {
1544 up_write(&snd_ioctl_rwsem);
1549 up_write(&snd_ioctl_rwsem);
1554 int snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn)
1556 return _snd_ctl_unregister_ioctl(fcn, &snd_control_ioctls);
1559 EXPORT_SYMBOL(snd_ctl_unregister_ioctl);
1561 #ifdef CONFIG_COMPAT
1562 int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn)
1564 return _snd_ctl_unregister_ioctl(fcn, &snd_control_compat_ioctls);
1567 EXPORT_SYMBOL(snd_ctl_unregister_ioctl_compat);
1570 static int snd_ctl_fasync(int fd, struct file * file, int on)
1572 struct snd_ctl_file *ctl;
1574 ctl = file->private_data;
1575 return fasync_helper(fd, file, on, &ctl->fasync);
1581 #ifdef CONFIG_COMPAT
1582 #include "control_compat.c"
1584 #define snd_ctl_ioctl_compat NULL
1591 static const struct file_operations snd_ctl_f_ops =
1593 .owner = THIS_MODULE,
1594 .read = snd_ctl_read,
1595 .open = snd_ctl_open,
1596 .release = snd_ctl_release,
1597 .llseek = no_llseek,
1598 .poll = snd_ctl_poll,
1599 .unlocked_ioctl = snd_ctl_ioctl,
1600 .compat_ioctl = snd_ctl_ioctl_compat,
1601 .fasync = snd_ctl_fasync,
1605 * registration of the control device
1607 static int snd_ctl_dev_register(struct snd_device *device)
1609 struct snd_card *card = device->device_data;
1613 if (snd_BUG_ON(!card))
1615 cardnum = card->number;
1616 if (snd_BUG_ON(cardnum < 0 || cardnum >= SNDRV_CARDS))
1618 sprintf(name, "controlC%i", cardnum);
1619 if ((err = snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
1620 &snd_ctl_f_ops, card, name)) < 0)
1626 * disconnection of the control device
1628 static int snd_ctl_dev_disconnect(struct snd_device *device)
1630 struct snd_card *card = device->device_data;
1631 struct snd_ctl_file *ctl;
1634 if (snd_BUG_ON(!card))
1636 cardnum = card->number;
1637 if (snd_BUG_ON(cardnum < 0 || cardnum >= SNDRV_CARDS))
1640 read_lock(&card->ctl_files_rwlock);
1641 list_for_each_entry(ctl, &card->ctl_files, list) {
1642 wake_up(&ctl->change_sleep);
1643 kill_fasync(&ctl->fasync, SIGIO, POLL_ERR);
1645 read_unlock(&card->ctl_files_rwlock);
1647 if ((err = snd_unregister_device(SNDRV_DEVICE_TYPE_CONTROL,
1656 static int snd_ctl_dev_free(struct snd_device *device)
1658 struct snd_card *card = device->device_data;
1659 struct snd_kcontrol *control;
1661 down_write(&card->controls_rwsem);
1662 while (!list_empty(&card->controls)) {
1663 control = snd_kcontrol(card->controls.next);
1664 snd_ctl_remove(card, control);
1666 up_write(&card->controls_rwsem);
1671 * create control core:
1672 * called from init.c
1674 int snd_ctl_create(struct snd_card *card)
1676 static struct snd_device_ops ops = {
1677 .dev_free = snd_ctl_dev_free,
1678 .dev_register = snd_ctl_dev_register,
1679 .dev_disconnect = snd_ctl_dev_disconnect,
1682 if (snd_BUG_ON(!card))
1684 return snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
1688 * Frequently used control callbacks/helpers
1690 int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
1691 struct snd_ctl_elem_info *uinfo)
1693 uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1695 uinfo->value.integer.min = 0;
1696 uinfo->value.integer.max = 1;
1700 EXPORT_SYMBOL(snd_ctl_boolean_mono_info);
1702 int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
1703 struct snd_ctl_elem_info *uinfo)
1705 uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
1707 uinfo->value.integer.min = 0;
1708 uinfo->value.integer.max = 1;
1712 EXPORT_SYMBOL(snd_ctl_boolean_stereo_info);
1715 * snd_ctl_enum_info - fills the info structure for an enumerated control
1716 * @info: the structure to be filled
1717 * @channels: the number of the control's channels; often one
1718 * @items: the number of control values; also the size of @names
1719 * @names: an array containing the names of all control values
1721 * Sets all required fields in @info to their appropriate values.
1722 * If the control's accessibility is not the default (readable and writable),
1723 * the caller has to fill @info->access.
1725 int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
1726 unsigned int items, const char *const names[])
1728 info->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
1729 info->count = channels;
1730 info->value.enumerated.items = items;
1731 if (info->value.enumerated.item >= items)
1732 info->value.enumerated.item = items - 1;
1733 strlcpy(info->value.enumerated.name,
1734 names[info->value.enumerated.item],
1735 sizeof(info->value.enumerated.name));
1738 EXPORT_SYMBOL(snd_ctl_enum_info);