sound/core/sound.c - arm/linux - Git at Google

 /*
  *  Advanced Linux Sound Architecture
  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
  *
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
  *   the Free Software Foundation; either version 2 of the License, or
  *   (at your option) any later version.
  *
  *   This program is distributed in the hope that it will be useful,
  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *   GNU General Public License for more details.
  *
  *   You should have received a copy of the GNU General Public License
  *   along with this program; if not, write to the Free Software
  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  *
  */

 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/smp_lock.h>
 #include <linux/time.h>
 #include <linux/device.h>
 #include <linux/moduleparam.h>
 #include <sound/core.h>
 #include <sound/minors.h>
 #include <sound/info.h>
 #include <sound/version.h>
 #include <sound/control.h>
 #include <sound/initval.h>
 #include <linux/kmod.h>
 #include <linux/mutex.h>

 #define SNDRV_OS_MINORS 256

 static int major = CONFIG_SND_MAJOR;
 int snd_major;
 EXPORT_SYMBOL(snd_major);

 static int cards_limit = 1;

 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
 MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
 MODULE_LICENSE("GPL");
 module_param(major, int, 0444);
 MODULE_PARM_DESC(major, "Major # for sound driver.");
 module_param(cards_limit, int, 0444);
 MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
 MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);

 /* this one holds the actual max. card number currently available.
  * as default, it's identical with cards_limit option.  when more
  * modules are loaded manually, this limit number increases, too.
  */
 int snd_ecards_limit;
 EXPORT_SYMBOL(snd_ecards_limit);

 static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
 static DEFINE_MUTEX(sound_mutex);

 #ifdef CONFIG_MODULES

 /**
  * snd_request_card - try to load the card module
  * @card: the card number
  *
  * Tries to load the module "snd-card-X" for the given card number
  * via request_module.  Returns immediately if already loaded.
  */
 void snd_request_card(int card)
 {
 	if (snd_card_locked(card))
 		return;
 	if (card < 0 || card >= cards_limit)
 		return;
 	request_module("snd-card-%i", card);
 }

 EXPORT_SYMBOL(snd_request_card);

 static void snd_request_other(int minor)
 {
 	char *str;

 	switch (minor) {
 	case SNDRV_MINOR_SEQUENCER:	str = "snd-seq";	break;
 	case SNDRV_MINOR_TIMER:		str = "snd-timer";	break;
 	default:			return;
 	}
 	request_module(str);
 }

 #endif	/* modular kernel */

 /**
  * snd_lookup_minor_data - get user data of a registered device
  * @minor: the minor number
  * @type: device type (SNDRV_DEVICE_TYPE_XXX)
  *
  * Checks that a minor device with the specified type is registered, and returns
  * its user data pointer.
  */
 void *snd_lookup_minor_data(unsigned int minor, int type)
 {
 	struct snd_minor *mreg;
 	void *private_data;

 	if (minor >= ARRAY_SIZE(snd_minors))
 		return NULL;
 	mutex_lock(&sound_mutex);
 	mreg = snd_minors[minor];
 	if (mreg && mreg->type == type)
 		private_data = mreg->private_data;
 	else
 		private_data = NULL;
 	mutex_unlock(&sound_mutex);
 	return private_data;
 }

 EXPORT_SYMBOL(snd_lookup_minor_data);

 static int __snd_open(struct inode *inode, struct file *file)
 {
 	unsigned int minor = iminor(inode);
 	struct snd_minor *mptr = NULL;
 	const struct file_operations *old_fops;
 	int err = 0;

 	if (minor >= ARRAY_SIZE(snd_minors))
 		return -ENODEV;
 	mptr = snd_minors[minor];
 	if (mptr == NULL) {
 #ifdef CONFIG_MODULES
 		int dev = SNDRV_MINOR_DEVICE(minor);
 		if (dev == SNDRV_MINOR_CONTROL) {
 			/* /dev/aloadC? */
 			int card = SNDRV_MINOR_CARD(minor);
 			if (snd_cards[card] == NULL)
 				snd_request_card(card);
 		} else if (dev == SNDRV_MINOR_GLOBAL) {
 			/* /dev/aloadSEQ */
 			snd_request_other(minor);
 		}
 #ifndef CONFIG_SND_DYNAMIC_MINORS
 		/* /dev/snd/{controlC?,seq} */
 		mptr = snd_minors[minor];
 		if (mptr == NULL)
 #endif
 #endif
 			return -ENODEV;
 	}
 	old_fops = file->f_op;
 	file->f_op = fops_get(mptr->f_ops);
 	if (file->f_op->open)
 		err = file->f_op->open(inode, file);
 	if (err) {
 		fops_put(file->f_op);
 		file->f_op = fops_get(old_fops);
 	}
 	fops_put(old_fops);
 	return err;
 }


 /* BKL pushdown: nasty #ifdef avoidance wrapper */
 static int snd_open(struct inode *inode, struct file *file)
 {
 	int ret;

 	lock_kernel();
 	ret = __snd_open(inode, file);
 	unlock_kernel();
 	return ret;
 }

 static const struct file_operations snd_fops =
 {
 	.owner =	THIS_MODULE,
 	.open =		snd_open
 };

 #ifdef CONFIG_SND_DYNAMIC_MINORS
 static int snd_find_free_minor(void)
 {
 	int minor;

 	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
 		/* skip minors still used statically for autoloading devices */
 		if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL ||
 		    minor == SNDRV_MINOR_SEQUENCER)
 			continue;
 		if (!snd_minors[minor])
 			return minor;
 	}
 	return -EBUSY;
 }
 #else
 static int snd_kernel_minor(int type, struct snd_card *card, int dev)
 {
 	int minor;

 	switch (type) {
 	case SNDRV_DEVICE_TYPE_SEQUENCER:
 	case SNDRV_DEVICE_TYPE_TIMER:
 		minor = type;
 		break;
 	case SNDRV_DEVICE_TYPE_CONTROL:
 		snd_assert(card != NULL, return -EINVAL);
 		minor = SNDRV_MINOR(card->number, type);
 		break;
 	case SNDRV_DEVICE_TYPE_HWDEP:
 	case SNDRV_DEVICE_TYPE_RAWMIDI:
 	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
 	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
 		snd_assert(card != NULL, return -EINVAL);
 		minor = SNDRV_MINOR(card->number, type + dev);
 		break;
 	default:
 		return -EINVAL;
 	}
 	snd_assert(minor >= 0 && minor < SNDRV_OS_MINORS, return -EINVAL);
 	return minor;
 }
 #endif

 /**
  * snd_register_device_for_dev - Register the ALSA device file for the card
  * @type: the device type, SNDRV_DEVICE_TYPE_XXX
  * @card: the card instance
  * @dev: the device index
  * @f_ops: the file operations
  * @private_data: user pointer for f_ops->open()
  * @name: the device file name
  * @device: the &struct device to link this new device to
  *
  * Registers an ALSA device file for the given card.
  * The operators have to be set in reg parameter.
  *
  * Returns zero if successful, or a negative error code on failure.
  */
 int snd_register_device_for_dev(int type, struct snd_card *card, int dev,
 				const struct file_operations *f_ops,
 				void *private_data,
 				const char *name, struct device *device)
 {
 	int minor;
 	struct snd_minor *preg;

 	snd_assert(name, return -EINVAL);
 	preg = kmalloc(sizeof *preg, GFP_KERNEL);
 	if (preg == NULL)
 		return -ENOMEM;
 	preg->type = type;
 	preg->card = card ? card->number : -1;
 	preg->device = dev;
 	preg->f_ops = f_ops;
 	preg->private_data = private_data;
 	mutex_lock(&sound_mutex);
 #ifdef CONFIG_SND_DYNAMIC_MINORS
 	minor = snd_find_free_minor();
 #else
 	minor = snd_kernel_minor(type, card, dev);
 	if (minor >= 0 && snd_minors[minor])
 		minor = -EBUSY;
 #endif
 	if (minor < 0) {
 		mutex_unlock(&sound_mutex);
 		kfree(preg);
 		return minor;
 	}
 	snd_minors[minor] = preg;
 	preg->dev = device_create_drvdata(sound_class, device,
 					  MKDEV(major, minor),
 					  private_data, "%s", name);
 	if (IS_ERR(preg->dev)) {
 		snd_minors[minor] = NULL;
 		mutex_unlock(&sound_mutex);
 		minor = PTR_ERR(preg->dev);
 		kfree(preg);
 		return minor;
 	}

 	mutex_unlock(&sound_mutex);
 	return 0;
 }

 EXPORT_SYMBOL(snd_register_device_for_dev);

 /* find the matching minor record
  * return the index of snd_minor, or -1 if not found
  */
 static int find_snd_minor(int type, struct snd_card *card, int dev)
 {
 	int cardnum, minor;
 	struct snd_minor *mptr;

 	cardnum = card ? card->number : -1;
 	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor)
 		if ((mptr = snd_minors[minor]) != NULL &&
 		    mptr->type == type &&
 		    mptr->card == cardnum &&
 		    mptr->device == dev)
 			return minor;
 	return -1;
 }

 /**
  * snd_unregister_device - unregister the device on the given card
  * @type: the device type, SNDRV_DEVICE_TYPE_XXX
  * @card: the card instance
  * @dev: the device index
  *
  * Unregisters the device file already registered via
  * snd_register_device().
  *
  * Returns zero if sucecessful, or a negative error code on failure
  */
 int snd_unregister_device(int type, struct snd_card *card, int dev)
 {
 	int minor;

 	mutex_lock(&sound_mutex);
 	minor = find_snd_minor(type, card, dev);
 	if (minor < 0) {
 		mutex_unlock(&sound_mutex);
 		return -EINVAL;
 	}

 	device_destroy(sound_class, MKDEV(major, minor));

 	kfree(snd_minors[minor]);
 	snd_minors[minor] = NULL;
 	mutex_unlock(&sound_mutex);
 	return 0;
 }

 EXPORT_SYMBOL(snd_unregister_device);

 int snd_add_device_sysfs_file(int type, struct snd_card *card, int dev,
 			      struct device_attribute *attr)
 {
 	int minor, ret = -EINVAL;
 	struct device *d;

 	mutex_lock(&sound_mutex);
 	minor = find_snd_minor(type, card, dev);
 	if (minor >= 0 && (d = snd_minors[minor]->dev) != NULL)
 		ret = device_create_file(d, attr);
 	mutex_unlock(&sound_mutex);
 	return ret;

 }

 EXPORT_SYMBOL(snd_add_device_sysfs_file);

 #ifdef CONFIG_PROC_FS
 /*
  *  INFO PART
  */

 static struct snd_info_entry *snd_minor_info_entry;

 static const char *snd_device_type_name(int type)
 {
 	switch (type) {
 	case SNDRV_DEVICE_TYPE_CONTROL:
 		return "control";
 	case SNDRV_DEVICE_TYPE_HWDEP:
 		return "hardware dependent";
 	case SNDRV_DEVICE_TYPE_RAWMIDI:
 		return "raw midi";
 	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
 		return "digital audio playback";
 	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
 		return "digital audio capture";
 	case SNDRV_DEVICE_TYPE_SEQUENCER:
 		return "sequencer";
 	case SNDRV_DEVICE_TYPE_TIMER:
 		return "timer";
 	default:
 		return "?";
 	}
 }

 static void snd_minor_info_read(struct snd_info_entry *entry, struct snd_info_buffer *buffer)
 {
 	int minor;
 	struct snd_minor *mptr;

 	mutex_lock(&sound_mutex);
 	for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
 		if (!(mptr = snd_minors[minor]))
 			continue;
 		if (mptr->card >= 0) {
 			if (mptr->device >= 0)
 				snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
 					    minor, mptr->card, mptr->device,
 					    snd_device_type_name(mptr->type));
 			else
 				snd_iprintf(buffer, "%3i: [%2i]   : %s\n",
 					    minor, mptr->card,
 					    snd_device_type_name(mptr->type));
 		} else
 			snd_iprintf(buffer, "%3i:        : %s\n", minor,
 				    snd_device_type_name(mptr->type));
 	}
 	mutex_unlock(&sound_mutex);
 }

 int __init snd_minor_info_init(void)
 {
 	struct snd_info_entry *entry;

 	entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
 	if (entry) {
 		entry->c.text.read = snd_minor_info_read;
 		if (snd_info_register(entry) < 0) {
 			snd_info_free_entry(entry);
 			entry = NULL;
 		}
 	}
 	snd_minor_info_entry = entry;
 	return 0;
 }

 int __exit snd_minor_info_done(void)
 {
 	snd_info_free_entry(snd_minor_info_entry);
 	return 0;
 }
 #endif /* CONFIG_PROC_FS */

 /*
  *  INIT PART
  */

 static int __init alsa_sound_init(void)
 {
 	snd_major = major;
 	snd_ecards_limit = cards_limit;
 	if (register_chrdev(major, "alsa", &snd_fops)) {
 		snd_printk(KERN_ERR "unable to register native major device number %d\n", major);
 		return -EIO;
 	}
 	if (snd_info_init() < 0) {
 		unregister_chrdev(major, "alsa");
 		return -ENOMEM;
 	}
 	snd_info_minor_register();
 #ifndef MODULE
 	printk(KERN_INFO "Advanced Linux Sound Architecture Driver Version " CONFIG_SND_VERSION CONFIG_SND_DATE ".\n");
 #endif
 	return 0;
 }

 static void __exit alsa_sound_exit(void)
 {
 	snd_info_minor_unregister();
 	snd_info_done();
 	unregister_chrdev(major, "alsa");
 }

 module_init(alsa_sound_init)
 module_exit(alsa_sound_exit)
	/*
	* Advanced Linux Sound Architecture
	* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
	*
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*
	*/

	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/smp_lock.h>
	#include <linux/time.h>
	#include <linux/device.h>
	#include <linux/moduleparam.h>
	#include <sound/core.h>
	#include <sound/minors.h>
	#include <sound/info.h>
	#include <sound/version.h>
	#include <sound/control.h>
	#include <sound/initval.h>
	#include <linux/kmod.h>
	#include <linux/mutex.h>

	#define SNDRV_OS_MINORS 256

	static int major = CONFIG_SND_MAJOR;
	int snd_major;
	EXPORT_SYMBOL(snd_major);

	static int cards_limit = 1;

	MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
	MODULE_DESCRIPTION("Advanced Linux Sound Architecture driver for soundcards.");
	MODULE_LICENSE("GPL");
	module_param(major, int, 0444);
	MODULE_PARM_DESC(major, "Major # for sound driver.");
	module_param(cards_limit, int, 0444);
	MODULE_PARM_DESC(cards_limit, "Count of auto-loadable soundcards.");
	MODULE_ALIAS_CHARDEV_MAJOR(CONFIG_SND_MAJOR);

	/* this one holds the actual max. card number currently available.
	* as default, it's identical with cards_limit option. when more
	* modules are loaded manually, this limit number increases, too.
	*/
	int snd_ecards_limit;
	EXPORT_SYMBOL(snd_ecards_limit);

	static struct snd_minor *snd_minors[SNDRV_OS_MINORS];
	static DEFINE_MUTEX(sound_mutex);

	#ifdef CONFIG_MODULES

	/**
	* snd_request_card - try to load the card module
	* @card: the card number
	*
	* Tries to load the module "snd-card-X" for the given card number
	* via request_module. Returns immediately if already loaded.
	*/
	void snd_request_card(int card)
	{
	if (snd_card_locked(card))
	return;
	if (card < 0 \|\| card >= cards_limit)
	return;
	request_module("snd-card-%i", card);
	}

	EXPORT_SYMBOL(snd_request_card);

	static void snd_request_other(int minor)
	{
	char *str;

	switch (minor) {
	case SNDRV_MINOR_SEQUENCER: str = "snd-seq"; break;
	case SNDRV_MINOR_TIMER: str = "snd-timer"; break;
	default: return;
	}
	request_module(str);
	}

	#endif /* modular kernel */

	/**
	* snd_lookup_minor_data - get user data of a registered device
	* @minor: the minor number
	* @type: device type (SNDRV_DEVICE_TYPE_XXX)
	*
	* Checks that a minor device with the specified type is registered, and returns
	* its user data pointer.
	*/
	void *snd_lookup_minor_data(unsigned int minor, int type)
	{
	struct snd_minor *mreg;
	void *private_data;

	if (minor >= ARRAY_SIZE(snd_minors))
	return NULL;
	mutex_lock(&sound_mutex);
	mreg = snd_minors[minor];
	if (mreg && mreg->type == type)
	private_data = mreg->private_data;
	else
	private_data = NULL;
	mutex_unlock(&sound_mutex);
	return private_data;
	}

	EXPORT_SYMBOL(snd_lookup_minor_data);

	static int __snd_open(struct inode inode, struct file file)
	{
	unsigned int minor = iminor(inode);
	struct snd_minor *mptr = NULL;
	const struct file_operations *old_fops;
	int err = 0;

	if (minor >= ARRAY_SIZE(snd_minors))
	return -ENODEV;
	mptr = snd_minors[minor];
	if (mptr == NULL) {
	#ifdef CONFIG_MODULES
	int dev = SNDRV_MINOR_DEVICE(minor);
	if (dev == SNDRV_MINOR_CONTROL) {
	/* /dev/aloadC? */
	int card = SNDRV_MINOR_CARD(minor);
	if (snd_cards[card] == NULL)
	snd_request_card(card);
	} else if (dev == SNDRV_MINOR_GLOBAL) {
	/* /dev/aloadSEQ */
	snd_request_other(minor);
	}
	#ifndef CONFIG_SND_DYNAMIC_MINORS
	/* /dev/snd/{controlC?,seq} */
	mptr = snd_minors[minor];
	if (mptr == NULL)
	#endif
	#endif
	return -ENODEV;
	}
	old_fops = file->f_op;
	file->f_op = fops_get(mptr->f_ops);
	if (file->f_op->open)
	err = file->f_op->open(inode, file);
	if (err) {
	fops_put(file->f_op);
	file->f_op = fops_get(old_fops);
	}
	fops_put(old_fops);
	return err;
	}


	/* BKL pushdown: nasty #ifdef avoidance wrapper */
	static int snd_open(struct inode inode, struct file file)
	{
	int ret;

	lock_kernel();
	ret = __snd_open(inode, file);
	unlock_kernel();
	return ret;
	}

	static const struct file_operations snd_fops =
	{
	.owner = THIS_MODULE,
	.open = snd_open
	};

	#ifdef CONFIG_SND_DYNAMIC_MINORS
	static int snd_find_free_minor(void)
	{
	int minor;

	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor) {
	/* skip minors still used statically for autoloading devices */
	if (SNDRV_MINOR_DEVICE(minor) == SNDRV_MINOR_CONTROL \|\|
	minor == SNDRV_MINOR_SEQUENCER)
	continue;
	if (!snd_minors[minor])
	return minor;
	}
	return -EBUSY;
	}
	#else
	static int snd_kernel_minor(int type, struct snd_card *card, int dev)
	{
	int minor;

	switch (type) {
	case SNDRV_DEVICE_TYPE_SEQUENCER:
	case SNDRV_DEVICE_TYPE_TIMER:
	minor = type;
	break;
	case SNDRV_DEVICE_TYPE_CONTROL:
	snd_assert(card != NULL, return -EINVAL);
	minor = SNDRV_MINOR(card->number, type);
	break;
	case SNDRV_DEVICE_TYPE_HWDEP:
	case SNDRV_DEVICE_TYPE_RAWMIDI:
	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
	snd_assert(card != NULL, return -EINVAL);
	minor = SNDRV_MINOR(card->number, type + dev);
	break;
	default:
	return -EINVAL;
	}
	snd_assert(minor >= 0 && minor < SNDRV_OS_MINORS, return -EINVAL);
	return minor;
	}
	#endif

	/**
	* snd_register_device_for_dev - Register the ALSA device file for the card
	* @type: the device type, SNDRV_DEVICE_TYPE_XXX
	* @card: the card instance
	* @dev: the device index
	* @f_ops: the file operations
	* @private_data: user pointer for f_ops->open()
	* @name: the device file name
	* @device: the &struct device to link this new device to
	*
	* Registers an ALSA device file for the given card.
	* The operators have to be set in reg parameter.
	*
	* Returns zero if successful, or a negative error code on failure.
	*/
	int snd_register_device_for_dev(int type, struct snd_card *card, int dev,
	const struct file_operations *f_ops,
	void *private_data,
	const char name, struct device device)
	{
	int minor;
	struct snd_minor *preg;

	snd_assert(name, return -EINVAL);
	preg = kmalloc(sizeof *preg, GFP_KERNEL);
	if (preg == NULL)
	return -ENOMEM;
	preg->type = type;
	preg->card = card ? card->number : -1;
	preg->device = dev;
	preg->f_ops = f_ops;
	preg->private_data = private_data;
	mutex_lock(&sound_mutex);
	#ifdef CONFIG_SND_DYNAMIC_MINORS
	minor = snd_find_free_minor();
	#else
	minor = snd_kernel_minor(type, card, dev);
	if (minor >= 0 && snd_minors[minor])
	minor = -EBUSY;
	#endif
	if (minor < 0) {
	mutex_unlock(&sound_mutex);
	kfree(preg);
	return minor;
	}
	snd_minors[minor] = preg;
	preg->dev = device_create_drvdata(sound_class, device,
	MKDEV(major, minor),
	private_data, "%s", name);
	if (IS_ERR(preg->dev)) {
	snd_minors[minor] = NULL;
	mutex_unlock(&sound_mutex);
	minor = PTR_ERR(preg->dev);
	kfree(preg);
	return minor;
	}

	mutex_unlock(&sound_mutex);
	return 0;
	}

	EXPORT_SYMBOL(snd_register_device_for_dev);

	/* find the matching minor record
	* return the index of snd_minor, or -1 if not found
	*/
	static int find_snd_minor(int type, struct snd_card *card, int dev)
	{
	int cardnum, minor;
	struct snd_minor *mptr;

	cardnum = card ? card->number : -1;
	for (minor = 0; minor < ARRAY_SIZE(snd_minors); ++minor)
	if ((mptr = snd_minors[minor]) != NULL &&
	mptr->type == type &&
	mptr->card == cardnum &&
	mptr->device == dev)
	return minor;
	return -1;
	}

	/**
	* snd_unregister_device - unregister the device on the given card
	* @type: the device type, SNDRV_DEVICE_TYPE_XXX
	* @card: the card instance
	* @dev: the device index
	*
	* Unregisters the device file already registered via
	* snd_register_device().
	*
	* Returns zero if sucecessful, or a negative error code on failure
	*/
	int snd_unregister_device(int type, struct snd_card *card, int dev)
	{
	int minor;

	mutex_lock(&sound_mutex);
	minor = find_snd_minor(type, card, dev);
	if (minor < 0) {
	mutex_unlock(&sound_mutex);
	return -EINVAL;
	}

	device_destroy(sound_class, MKDEV(major, minor));

	kfree(snd_minors[minor]);
	snd_minors[minor] = NULL;
	mutex_unlock(&sound_mutex);
	return 0;
	}

	EXPORT_SYMBOL(snd_unregister_device);

	int snd_add_device_sysfs_file(int type, struct snd_card *card, int dev,
	struct device_attribute *attr)
	{
	int minor, ret = -EINVAL;
	struct device *d;

	mutex_lock(&sound_mutex);
	minor = find_snd_minor(type, card, dev);
	if (minor >= 0 && (d = snd_minors[minor]->dev) != NULL)
	ret = device_create_file(d, attr);
	mutex_unlock(&sound_mutex);
	return ret;

	}

	EXPORT_SYMBOL(snd_add_device_sysfs_file);

	#ifdef CONFIG_PROC_FS
	/*
	* INFO PART
	*/

	static struct snd_info_entry *snd_minor_info_entry;

	static const char *snd_device_type_name(int type)
	{
	switch (type) {
	case SNDRV_DEVICE_TYPE_CONTROL:
	return "control";
	case SNDRV_DEVICE_TYPE_HWDEP:
	return "hardware dependent";
	case SNDRV_DEVICE_TYPE_RAWMIDI:
	return "raw midi";
	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
	return "digital audio playback";
	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
	return "digital audio capture";
	case SNDRV_DEVICE_TYPE_SEQUENCER:
	return "sequencer";
	case SNDRV_DEVICE_TYPE_TIMER:
	return "timer";
	default:
	return "?";
	}
	}

	static void snd_minor_info_read(struct snd_info_entry entry, struct snd_info_buffer buffer)
	{
	int minor;
	struct snd_minor *mptr;

	mutex_lock(&sound_mutex);
	for (minor = 0; minor < SNDRV_OS_MINORS; ++minor) {
	if (!(mptr = snd_minors[minor]))
	continue;
	if (mptr->card >= 0) {
	if (mptr->device >= 0)
	snd_iprintf(buffer, "%3i: [%2i-%2i]: %s\n",
	minor, mptr->card, mptr->device,
	snd_device_type_name(mptr->type));
	else
	snd_iprintf(buffer, "%3i: [%2i] : %s\n",
	minor, mptr->card,
	snd_device_type_name(mptr->type));
	} else
	snd_iprintf(buffer, "%3i: : %s\n", minor,
	snd_device_type_name(mptr->type));
	}
	mutex_unlock(&sound_mutex);
	}

	int __init snd_minor_info_init(void)
	{
	struct snd_info_entry *entry;

	entry = snd_info_create_module_entry(THIS_MODULE, "devices", NULL);
	if (entry) {
	entry->c.text.read = snd_minor_info_read;
	if (snd_info_register(entry) < 0) {
	snd_info_free_entry(entry);
	entry = NULL;
	}
	}
	snd_minor_info_entry = entry;
	return 0;
	}

	int __exit snd_minor_info_done(void)
	{
	snd_info_free_entry(snd_minor_info_entry);
	return 0;
	}
	#endif /* CONFIG_PROC_FS */

	/*
	* INIT PART
	*/

	static int __init alsa_sound_init(void)
	{
	snd_major = major;
	snd_ecards_limit = cards_limit;
	if (register_chrdev(major, "alsa", &snd_fops)) {
	snd_printk(KERN_ERR "unable to register native major device number %d\n", major);
	return -EIO;
	}
	if (snd_info_init() < 0) {
	unregister_chrdev(major, "alsa");
	return -ENOMEM;
	}
	snd_info_minor_register();
	#ifndef MODULE
	printk(KERN_INFO "Advanced Linux Sound Architecture Driver Version " CONFIG_SND_VERSION CONFIG_SND_DATE ".\n");
	#endif
	return 0;
	}

	static void __exit alsa_sound_exit(void)
	{
	snd_info_minor_unregister();
	snd_info_done();
	unregister_chrdev(major, "alsa");
	}

	module_init(alsa_sound_init)
	module_exit(alsa_sound_exit)