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* Advanced Linux Sound Architecture
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* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/time.h>
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#include <linux/device.h>
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#include <linux/module.h>
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#include <sound/core.h>
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#include <sound/minors.h>
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#include <sound/info.h>
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#include <sound/version.h>
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#include <sound/control.h>
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#include <sound/initval.h>
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#include <linux/kmod.h>
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#include <linux/mutex.h>
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static int major = CONFIG_SND_MAJOR;
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EXPORT_SYMBOL(snd_major);
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static int cards_limit = 1;
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MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
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MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
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MODULE_LICENSE("GPL");
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module_param(major, int, 0444);
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MODULE_PARM_DESC(major, "Major # for sound driver.");
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module_param(cards_limit, int, 0444);
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MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
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MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);
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/* this one holds the actual max. card number currently available.
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* as default, it's identical with cards_limit option. when more
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* modules are loaded manually, this limit number increases, too.
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EXPORT_SYMBOL(snd_ecards_limit);
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static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
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static DEFINE_MUTEX(sound_mutex);
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* snd_request_card - try to load the card module
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* @card: the card number
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* Tries to load the module "snd-card-X" for the given card number
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* via request_module. Returns immediately if already loaded.
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void snd_request_card(int card)
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if (snd_card_locked(card))
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if (card < 0 || card >= cards_limit)
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request_module("snd-card-%i", card);
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EXPORT_SYMBOL(snd_request_card);
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static void snd_request_other(int minor)
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case SNDRV_MINOR_SEQUENCER: str = "snd-seq"; break;
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case SNDRV_MINOR_TIMER: str = "snd-timer"; break;
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#endif /* modular kernel */
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* snd_lookup_minor_data - get user data of a registered device
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* @minor: the minor number
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* @type: device type (SNDRV_DEVICE_TYPE_XXX)
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* Checks that a minor device with the specified type is registered, and returns
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* its user data pointer.
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void *snd_lookup_minor_data(unsigned int minor, int type)
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struct snd_minor *mreg;
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if (minor >= ARRAY_SIZE(snd_minors))
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mutex_lock(&sound_mutex);
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mreg = snd_minors[minor];
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if (mreg && mreg->type == type)
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private_data = mreg->private_data;
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mutex_unlock(&sound_mutex);
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EXPORT_SYMBOL(snd_lookup_minor_data);
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#ifdef CONFIG_MODULES
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static struct snd_minor *autoload_device(unsigned int minor)
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mutex_unlock(&sound_mutex); /* release lock temporarily */
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dev = SNDRV_MINOR_DEVICE(minor);
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if (dev == SNDRV_MINOR_CONTROL) {
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int card = SNDRV_MINOR_CARD(minor);
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if (snd_cards[card] == NULL)
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snd_request_card(card);
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} else if (dev == SNDRV_MINOR_GLOBAL) {
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snd_request_other(minor);
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mutex_lock(&sound_mutex); /* reacuire lock */
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return snd_minors[minor];
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#else /* !CONFIG_MODULES */
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#define autoload_device(minor) NULL
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#endif /* CONFIG_MODULES */
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static int snd_open(struct inode *inode, struct file *file)
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unsigned int minor = iminor(inode);
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struct snd_minor *mptr = NULL;
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const struct file_operations *old_fops;
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if (minor >= ARRAY_SIZE(snd_minors))
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mutex_lock(&sound_mutex);
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mptr = snd_minors[minor];
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mptr = autoload_device(minor);
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mutex_unlock(&sound_mutex);
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old_fops = file->f_op;
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file->f_op = fops_get(mptr->f_ops);
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if (file->f_op == NULL) {
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file->f_op = old_fops;
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mutex_unlock(&sound_mutex);
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if (file->f_op->open) {
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err = file->f_op->open(inode, file);
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fops_put(file->f_op);
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file->f_op = fops_get(old_fops);
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static const struct file_operations snd_fops =
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.owner = THIS_MODULE,
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.llseek = noop_llseek,
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#ifdef CONFIG_SND_DYNAMIC_MINORS
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static int snd_find_free_minor(int type)
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/* static minors for module auto loading */
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if (type == SNDRV_DEVICE_TYPE_SEQUENCER)
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return SNDRV_MINOR_SEQUENCER;
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if (type == SNDRV_DEVICE_TYPE_TIMER)
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return SNDRV_MINOR_TIMER;
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for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
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/* skip static minors still used for module auto loading */
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if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL)
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if (minor == SNDRV_MINOR_SEQUENCER ||
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minor == SNDRV_MINOR_TIMER)
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if (!snd_minors[minor])
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static int snd_kernel_minor(int type, struct snd_card *card, int dev)
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case SNDRV_DEVICE_TYPE_SEQUENCER:
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case SNDRV_DEVICE_TYPE_TIMER:
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case SNDRV_DEVICE_TYPE_CONTROL:
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if (snd_BUG_ON(!card))
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minor = SNDRV_MINOR(card->number, type);
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case SNDRV_DEVICE_TYPE_HWDEP:
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case SNDRV_DEVICE_TYPE_RAWMIDI:
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case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
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case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
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if (snd_BUG_ON(!card))
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minor = SNDRV_MINOR(card->number, type + dev);
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if (snd_BUG_ON(minor < 0 || minor >= SNDRV_OS_MINORS))
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* snd_register_device_for_dev - Register the ALSA device file for the card
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* @type: the device type, SNDRV_DEVICE_TYPE_XXX
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* @card: the card instance
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* @dev: the device index
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* @f_ops: the file operations
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* @private_data: user pointer for f_ops->open()
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* @name: the device file name
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* @device: the &struct device to link this new device to
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* Registers an ALSA device file for the given card.
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* The operators have to be set in reg parameter.
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* Returns zero if successful, or a negative error code on failure.
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int snd_register_device_for_dev(int type, struct snd_card *card, int dev,
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const struct file_operations *f_ops,
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const char *name, struct device *device)
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struct snd_minor *preg;
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if (snd_BUG_ON(!name))
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preg = kmalloc(sizeof *preg, GFP_KERNEL);
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preg->card = card ? card->number : -1;
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preg->private_data = private_data;
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mutex_lock(&sound_mutex);
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#ifdef CONFIG_SND_DYNAMIC_MINORS
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minor = snd_find_free_minor(type);
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minor = snd_kernel_minor(type, card, dev);
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if (minor >= 0 && snd_minors[minor])
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mutex_unlock(&sound_mutex);
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snd_minors[minor] = preg;
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preg->dev = device_create(sound_class, device, MKDEV(major, minor),
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private_data, "%s", name);
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if (IS_ERR(preg->dev)) {
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snd_minors[minor] = NULL;
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mutex_unlock(&sound_mutex);
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minor = PTR_ERR(preg->dev);
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mutex_unlock(&sound_mutex);
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EXPORT_SYMBOL(snd_register_device_for_dev);
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/* find the matching minor record
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* return the index of snd_minor, or -1 if not found
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static int find_snd_minor(int type, struct snd_card *card, int dev)
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struct snd_minor *mptr;
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cardnum = card ? card->number : -1;
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for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor)
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if ((mptr = snd_minors[minor]) != NULL &&
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mptr->type == type &&
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mptr->card == cardnum &&
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* snd_unregister_device - unregister the device on the given card
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* @type: the device type, SNDRV_DEVICE_TYPE_XXX
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* @card: the card instance
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* @dev: the device index
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* Unregisters the device file already registered via
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* snd_register_device().
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* Returns zero if sucecessful, or a negative error code on failure
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int snd_unregister_device(int type, struct snd_card *card, int dev)
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mutex_lock(&sound_mutex);
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minor = find_snd_minor(type, card, dev);
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mutex_unlock(&sound_mutex);
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device_destroy(sound_class, MKDEV(major, minor));
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kfree(snd_minors[minor]);
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snd_minors[minor] = NULL;
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mutex_unlock(&sound_mutex);
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EXPORT_SYMBOL(snd_unregister_device);
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int snd_add_device_sysfs_file(int type, struct snd_card *card, int dev,
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struct device_attribute *attr)
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int minor, ret = -EINVAL;
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mutex_lock(&sound_mutex);
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minor = find_snd_minor(type, card, dev);
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if (minor >= 0 && (d = snd_minors[minor]->dev) != NULL)
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ret = device_create_file(d, attr);
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mutex_unlock(&sound_mutex);
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EXPORT_SYMBOL(snd_add_device_sysfs_file);
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#ifdef CONFIG_PROC_FS
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static struct snd_info_entry *snd_minor_info_entry;
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static const char *snd_device_type_name(int type)
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case SNDRV_DEVICE_TYPE_CONTROL:
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case SNDRV_DEVICE_TYPE_HWDEP:
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return "hardware dependent";
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case SNDRV_DEVICE_TYPE_RAWMIDI:
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case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
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return "digital audio playback";
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case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
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return "digital audio capture";
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case SNDRV_DEVICE_TYPE_SEQUENCER:
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case SNDRV_DEVICE_TYPE_TIMER:
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static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
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struct snd_minor *mptr;
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mutex_lock(&sound_mutex);
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for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
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if (!(mptr = snd_minors[minor]))
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if (mptr->card >= 0) {
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if (mptr->device >= 0)
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snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
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minor, mptr->card, mptr->device,
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snd_device_type_name(mptr->type));
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snd_iprintf(buffer, "%3i: [%2i] : %s\n",
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snd_device_type_name(mptr->type));
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snd_iprintf(buffer, "%3i: : %s\n", minor,
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snd_device_type_name(mptr->type));
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mutex_unlock(&sound_mutex);
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int __init snd_minor_info_init(void)
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struct snd_info_entry *entry;
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entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
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entry->c.text.read = snd_minor_info_read;
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if (snd_info_register(entry) < 0) {
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snd_info_free_entry(entry);
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snd_minor_info_entry = entry;
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int __exit snd_minor_info_done(void)
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snd_info_free_entry(snd_minor_info_entry);
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#endif /* CONFIG_PROC_FS */
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static int __init alsa_sound_init(void)
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snd_ecards_limit = cards_limit;
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if (register_chrdev(major, "alsa", &snd_fops)) {
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snd_printk(KERN_ERR "unable to register native major device number %d\n", major);
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if (snd_info_init() < 0) {
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unregister_chrdev(major, "alsa");
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snd_info_minor_register();
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printk(KERN_INFO "Advanced Linux Sound Architecture Driver Version " CONFIG_SND_VERSION CONFIG_SND_DATE ".\n");
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static void __exit alsa_sound_exit(void)
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snd_info_minor_unregister();
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unregister_chrdev(major, "alsa");
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subsys_initcall(alsa_sound_init);
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module_exit(alsa_sound_exit);