SYNC_FILE_RANGE_WRITE may and will block. Document that.

[linux-2.6/mini2440.git] / sound / core / init.c

/*
 *  Initialization routines
 *  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/sched.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/ctype.h>
#include <linux/pm.h>

#include <sound/core.h>
#include <sound/control.h>
#include <sound/info.h>

static DEFINE_SPINLOCK(shutdown_lock);
static LIST_HEAD(shutdown_files);

static const struct file_operations snd_shutdown_f_ops;

static unsigned int snd_cards_lock;     /* locked for registering/using */
struct snd_card *snd_cards[SNDRV_CARDS];
EXPORT_SYMBOL(snd_cards);

static DEFINE_MUTEX(snd_card_mutex);

static char *slots[SNDRV_CARDS];
module_param_array(slots, charp, NULL, 0444);
MODULE_PARM_DESC(slots, "Module names assigned to the slots.");

/* return non-zero if the given index is reserved for the given
 * module via slots option
 */
static int module_slot_match(struct module *module, int idx)
{
        int match = 1;
#ifdef MODULE
        const char *s1, *s2;

        if (!module || !module->name || !slots[idx])
                return 0;

        s1 = module->name;
        s2 = slots[idx];
        if (*s2 == '!') {
                match = 0; /* negative match */
                s2++;
        }
        /* compare module name strings
         * hyphens are handled as equivalent with underscore
         */
        for (;;) {
                char c1 = *s1++;
                char c2 = *s2++;
                if (c1 == '-')
                        c1 = '_';
                if (c2 == '-')
                        c2 = '_';
                if (c1 != c2)
                        return !match;
                if (!c1)
                        break;
        }
#endif /* MODULE */
        return match;
}

#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
int (*snd_mixer_oss_notify_callback)(struct snd_card *card, int free_flag);
EXPORT_SYMBOL(snd_mixer_oss_notify_callback);
#endif

#ifdef CONFIG_PROC_FS
static void snd_card_id_read(struct snd_info_entry *entry,
                             struct snd_info_buffer *buffer)
{
        snd_iprintf(buffer, "%s\n", entry->card->id);
}

static inline int init_info_for_card(struct snd_card *card)
{
        int err;
        struct snd_info_entry *entry;

        if ((err = snd_info_card_register(card)) < 0) {
                snd_printd("unable to create card info\n");
                return err;
        }
        if ((entry = snd_info_create_card_entry(card, "id", card->proc_root)) == NULL) {
                snd_printd("unable to create card entry\n");
                return err;
        }
        entry->c.text.read = snd_card_id_read;
        if (snd_info_register(entry) < 0) {
                snd_info_free_entry(entry);
                entry = NULL;
        }
        card->proc_id = entry;
        return 0;
}
#else /* !CONFIG_PROC_FS */
#define init_info_for_card(card)
#endif

/**
 *  snd_card_new - create and initialize a soundcard structure
 *  @idx: card index (address) [0 ... (SNDRV_CARDS-1)]
 *  @xid: card identification (ASCII string)
 *  @module: top level module for locking
 *  @extra_size: allocate this extra size after the main soundcard structure
 *
 *  Creates and initializes a soundcard structure.
 *
 *  Returns kmallocated snd_card structure. Creates the ALSA control interface
 *  (which is blocked until snd_card_register function is called).
 */
struct snd_card *snd_card_new(int idx, const char *xid,
                         struct module *module, int extra_size)
{
        struct snd_card *card;
        int err, idx2;

        if (extra_size < 0)
                extra_size = 0;
        card = kzalloc(sizeof(*card) + extra_size, GFP_KERNEL);
        if (card == NULL)
                return NULL;
        if (xid) {
                if (!snd_info_check_reserved_words(xid))
                        goto __error;
                strlcpy(card->id, xid, sizeof(card->id));
        }
        err = 0;
        mutex_lock(&snd_card_mutex);
        if (idx < 0) {
                for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++)
                        /* idx == -1 == 0xffff means: take any free slot */
                        if (~snd_cards_lock & idx & 1<<idx2) {
                                if (module_slot_match(module, idx2)) {
                                        idx = idx2;
                                        break;
                                }
                        }
        }
        if (idx < 0) {
                for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++)
                        /* idx == -1 == 0xffff means: take any free slot */
                        if (~snd_cards_lock & idx & 1<<idx2) {
                                if (!slots[idx2] || !*slots[idx2]) {
                                        idx = idx2;
                                        break;
                                }
                        }
        }
        if (idx < 0)
                err = -ENODEV;
        else if (idx < snd_ecards_limit) {
                if (snd_cards_lock & (1 << idx))
                        err = -EBUSY;   /* invalid */
        } else if (idx >= SNDRV_CARDS)
                err = -ENODEV;
        if (err < 0) {
                mutex_unlock(&snd_card_mutex);
                snd_printk(KERN_ERR "cannot find the slot for index %d (range 0-%i), error: %d\n",
                         idx, snd_ecards_limit - 1, err);
                goto __error;
        }
        snd_cards_lock |= 1 << idx;             /* lock it */
        if (idx >= snd_ecards_limit)
                snd_ecards_limit = idx + 1; /* increase the limit */
        mutex_unlock(&snd_card_mutex);
        card->number = idx;
        card->module = module;
        INIT_LIST_HEAD(&card->devices);
        init_rwsem(&card->controls_rwsem);
        rwlock_init(&card->ctl_files_rwlock);
        INIT_LIST_HEAD(&card->controls);
        INIT_LIST_HEAD(&card->ctl_files);
        spin_lock_init(&card->files_lock);
        init_waitqueue_head(&card->shutdown_sleep);
#ifdef CONFIG_PM
        mutex_init(&card->power_lock);
        init_waitqueue_head(&card->power_sleep);
#endif
        /* the control interface cannot be accessed from the user space until */
        /* snd_cards_bitmask and snd_cards are set with snd_card_register */
        if ((err = snd_ctl_create(card)) < 0) {
                snd_printd("unable to register control minors\n");
                goto __error;
        }
        if ((err = snd_info_card_create(card)) < 0) {
                snd_printd("unable to create card info\n");
                goto __error_ctl;
        }
        if (extra_size > 0)
                card->private_data = (char *)card + sizeof(struct snd_card);
        return card;

      __error_ctl:
        snd_device_free_all(card, SNDRV_DEV_CMD_PRE);
      __error:
        kfree(card);
        return NULL;
}

EXPORT_SYMBOL(snd_card_new);

/* return non-zero if a card is already locked */
int snd_card_locked(int card)
{
        int locked;

        mutex_lock(&snd_card_mutex);
        locked = snd_cards_lock & (1 << card);
        mutex_unlock(&snd_card_mutex);
        return locked;
}

static loff_t snd_disconnect_llseek(struct file *file, loff_t offset, int orig)
{
        return -ENODEV;
}

static ssize_t snd_disconnect_read(struct file *file, char __user *buf,
                                   size_t count, loff_t *offset)
{
        return -ENODEV;
}

static ssize_t snd_disconnect_write(struct file *file, const char __user *buf,
                                    size_t count, loff_t *offset)
{
        return -ENODEV;
}

static int snd_disconnect_release(struct inode *inode, struct file *file)
{
        struct snd_monitor_file *df = NULL, *_df;

        spin_lock(&shutdown_lock);
        list_for_each_entry(_df, &shutdown_files, shutdown_list) {
                if (_df->file == file) {
                        df = _df;
                        break;
                }
        }
        spin_unlock(&shutdown_lock);

        if (likely(df))
                return df->disconnected_f_op->release(inode, file);

        panic("%s(%p, %p) failed!", __func__, inode, file);
}

static unsigned int snd_disconnect_poll(struct file * file, poll_table * wait)
{
        return POLLERR | POLLNVAL;
}

static long snd_disconnect_ioctl(struct file *file,
                                 unsigned int cmd, unsigned long arg)
{
        return -ENODEV;
}

static int snd_disconnect_mmap(struct file *file, struct vm_area_struct *vma)
{
        return -ENODEV;
}

static int snd_disconnect_fasync(int fd, struct file *file, int on)
{
        return -ENODEV;
}

static const struct file_operations snd_shutdown_f_ops =
{
        .owner =        THIS_MODULE,
        .llseek =       snd_disconnect_llseek,
        .read =         snd_disconnect_read,
        .write =        snd_disconnect_write,
        .release =      snd_disconnect_release,
        .poll =         snd_disconnect_poll,
        .unlocked_ioctl = snd_disconnect_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl = snd_disconnect_ioctl,
#endif
        .mmap =         snd_disconnect_mmap,
        .fasync =       snd_disconnect_fasync
};

/**
 *  snd_card_disconnect - disconnect all APIs from the file-operations (user space)
 *  @card: soundcard structure
 *
 *  Disconnects all APIs from the file-operations (user space).
 *
 *  Returns zero, otherwise a negative error code.
 *
 *  Note: The current implementation replaces all active file->f_op with special
 *        dummy file operations (they do nothing except release).
 */
int snd_card_disconnect(struct snd_card *card)
{
        struct snd_monitor_file *mfile;
        struct file *file;
        int err;

        if (!card)
                return -EINVAL;

        spin_lock(&card->files_lock);
        if (card->shutdown) {
                spin_unlock(&card->files_lock);
                return 0;
        }
        card->shutdown = 1;
        spin_unlock(&card->files_lock);

        /* phase 1: disable fops (user space) operations for ALSA API */
        mutex_lock(&snd_card_mutex);
        snd_cards[card->number] = NULL;
        snd_cards_lock &= ~(1 << card->number);
        mutex_unlock(&snd_card_mutex);
        
        /* phase 2: replace file->f_op with special dummy operations */
        
        spin_lock(&card->files_lock);
        mfile = card->files;
        while (mfile) {
                file = mfile->file;

                /* it's critical part, use endless loop */
                /* we have no room to fail */
                mfile->disconnected_f_op = mfile->file->f_op;

                spin_lock(&shutdown_lock);
                list_add(&mfile->shutdown_list, &shutdown_files);
                spin_unlock(&shutdown_lock);

                mfile->file->f_op = &snd_shutdown_f_ops;
                fops_get(mfile->file->f_op);
                
                mfile = mfile->next;
        }
        spin_unlock(&card->files_lock); 

        /* phase 3: notify all connected devices about disconnection */
        /* at this point, they cannot respond to any calls except release() */

#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
        if (snd_mixer_oss_notify_callback)
                snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_DISCONNECT);
#endif

        /* notify all devices that we are disconnected */
        err = snd_device_disconnect_all(card);
        if (err < 0)
                snd_printk(KERN_ERR "not all devices for card %i can be disconnected\n", card->number);

        snd_info_card_disconnect(card);
#ifndef CONFIG_SYSFS_DEPRECATED
        if (card->card_dev) {
                device_unregister(card->card_dev);
                card->card_dev = NULL;
        }
#endif
#ifdef CONFIG_PM
        wake_up(&card->power_sleep);
#endif
        return 0;       
}

EXPORT_SYMBOL(snd_card_disconnect);

/**
 *  snd_card_free - frees given soundcard structure
 *  @card: soundcard structure
 *
 *  This function releases the soundcard structure and the all assigned
 *  devices automatically.  That is, you don't have to release the devices
 *  by yourself.
 *
 *  Returns zero. Frees all associated devices and frees the control
 *  interface associated to given soundcard.
 */
static int snd_card_do_free(struct snd_card *card)
{
#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
        if (snd_mixer_oss_notify_callback)
                snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_FREE);
#endif
        if (snd_device_free_all(card, SNDRV_DEV_CMD_PRE) < 0) {
                snd_printk(KERN_ERR "unable to free all devices (pre)\n");
                /* Fatal, but this situation should never occur */
        }
        if (snd_device_free_all(card, SNDRV_DEV_CMD_NORMAL) < 0) {
                snd_printk(KERN_ERR "unable to free all devices (normal)\n");
                /* Fatal, but this situation should never occur */
        }
        if (snd_device_free_all(card, SNDRV_DEV_CMD_POST) < 0) {
                snd_printk(KERN_ERR "unable to free all devices (post)\n");
                /* Fatal, but this situation should never occur */
        }
        if (card->private_free)
                card->private_free(card);
        snd_info_free_entry(card->proc_id);
        if (snd_info_card_free(card) < 0) {
                snd_printk(KERN_WARNING "unable to free card info\n");
                /* Not fatal error */
        }
        kfree(card);
        return 0;
}

int snd_card_free_when_closed(struct snd_card *card)
{
        int free_now = 0;
        int ret = snd_card_disconnect(card);
        if (ret)
                return ret;

        spin_lock(&card->files_lock);
        if (card->files == NULL)
                free_now = 1;
        else
                card->free_on_last_close = 1;
        spin_unlock(&card->files_lock);

        if (free_now)
                snd_card_do_free(card);
        return 0;
}

EXPORT_SYMBOL(snd_card_free_when_closed);

int snd_card_free(struct snd_card *card)
{
        int ret = snd_card_disconnect(card);
        if (ret)
                return ret;

        /* wait, until all devices are ready for the free operation */
        wait_event(card->shutdown_sleep, card->files == NULL);
        snd_card_do_free(card);
        return 0;
}

EXPORT_SYMBOL(snd_card_free);

static void choose_default_id(struct snd_card *card)
{
        int i, len, idx_flag = 0, loops = SNDRV_CARDS;
        char *id, *spos;
        
        id = spos = card->shortname;    
        while (*id != '\0') {
                if (*id == ' ')
                        spos = id + 1;
                id++;
        }
        id = card->id;
        while (*spos != '\0' && !isalnum(*spos))
                spos++;
        if (isdigit(*spos))
                *id++ = isalpha(card->shortname[0]) ? card->shortname[0] : 'D';
        while (*spos != '\0' && (size_t)(id - card->id) < sizeof(card->id) - 1) {
                if (isalnum(*spos))
                        *id++ = *spos;
                spos++;
        }
        *id = '\0';

        id = card->id;
        
        if (*id == '\0')
                strcpy(id, "default");

        while (1) {
                if (loops-- == 0) {
                        snd_printk(KERN_ERR "unable to choose default card id (%s)\n", id);
                        strcpy(card->id, card->proc_root->name);
                        return;
                }
                if (!snd_info_check_reserved_words(id))
                        goto __change;
                for (i = 0; i < snd_ecards_limit; i++) {
                        if (snd_cards[i] && !strcmp(snd_cards[i]->id, id))
                                goto __change;
                }
                break;

              __change:
                len = strlen(id);
                if (idx_flag) {
                        if (id[len-1] != '9')
                                id[len-1]++;
                        else
                                id[len-1] = 'A';
                } else if ((size_t)len <= sizeof(card->id) - 3) {
                        strcat(id, "_1");
                        idx_flag++;
                } else {
                        spos = id + len - 2;
                        if ((size_t)len <= sizeof(card->id) - 2)
                                spos++;
                        *spos++ = '_';
                        *spos++ = '1';
                        *spos++ = '\0';
                        idx_flag++;
                }
        }
}

/**
 *  snd_card_register - register the soundcard
 *  @card: soundcard structure
 *
 *  This function registers all the devices assigned to the soundcard.
 *  Until calling this, the ALSA control interface is blocked from the
 *  external accesses.  Thus, you should call this function at the end
 *  of the initialization of the card.
 *
 *  Returns zero otherwise a negative error code if the registrain failed.
 */
int snd_card_register(struct snd_card *card)
{
        int err;

        snd_assert(card != NULL, return -EINVAL);
#ifndef CONFIG_SYSFS_DEPRECATED
        if (!card->card_dev) {
                card->card_dev = device_create_drvdata(sound_class, card->dev,
                                                       MKDEV(0, 0), NULL,
                                                       "card%i", card->number);
                if (IS_ERR(card->card_dev))
                        card->card_dev = NULL;
        }
#endif
        if ((err = snd_device_register_all(card)) < 0)
                return err;
        mutex_lock(&snd_card_mutex);
        if (snd_cards[card->number]) {
                /* already registered */
                mutex_unlock(&snd_card_mutex);
                return 0;
        }
        if (card->id[0] == '\0')
                choose_default_id(card);
        snd_cards[card->number] = card;
        mutex_unlock(&snd_card_mutex);
        init_info_for_card(card);
#if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
        if (snd_mixer_oss_notify_callback)
                snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_REGISTER);
#endif
        return 0;
}

EXPORT_SYMBOL(snd_card_register);

#ifdef CONFIG_PROC_FS
static struct snd_info_entry *snd_card_info_entry;

static void snd_card_info_read(struct snd_info_entry *entry,
                               struct snd_info_buffer *buffer)
{
        int idx, count;
        struct snd_card *card;

        for (idx = count = 0; idx < SNDRV_CARDS; idx++) {
                mutex_lock(&snd_card_mutex);
                if ((card = snd_cards[idx]) != NULL) {
                        count++;
                        snd_iprintf(buffer, "%2i [%-15s]: %s - %s\n",
                                        idx,
                                        card->id,
                                        card->driver,
                                        card->shortname);
                        snd_iprintf(buffer, "                      %s\n",
                                        card->longname);
                }
                mutex_unlock(&snd_card_mutex);
        }
        if (!count)
                snd_iprintf(buffer, "--- no soundcards ---\n");
}

#ifdef CONFIG_SND_OSSEMUL

void snd_card_info_read_oss(struct snd_info_buffer *buffer)
{
        int idx, count;
        struct snd_card *card;

        for (idx = count = 0; idx < SNDRV_CARDS; idx++) {
                mutex_lock(&snd_card_mutex);
                if ((card = snd_cards[idx]) != NULL) {
                        count++;
                        snd_iprintf(buffer, "%s\n", card->longname);
                }
                mutex_unlock(&snd_card_mutex);
        }
        if (!count) {
                snd_iprintf(buffer, "--- no soundcards ---\n");
        }
}

#endif

#ifdef MODULE
static struct snd_info_entry *snd_card_module_info_entry;
static void snd_card_module_info_read(struct snd_info_entry *entry,
                                      struct snd_info_buffer *buffer)
{
        int idx;
        struct snd_card *card;

        for (idx = 0; idx < SNDRV_CARDS; idx++) {
                mutex_lock(&snd_card_mutex);
                if ((card = snd_cards[idx]) != NULL)
                        snd_iprintf(buffer, "%2i %s\n",
                                    idx, card->module->name);
                mutex_unlock(&snd_card_mutex);
        }
}
#endif

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

        entry = snd_info_create_module_entry(THIS_MODULE, "cards", NULL);
        if (! entry)
                return -ENOMEM;
        entry->c.text.read = snd_card_info_read;
        if (snd_info_register(entry) < 0) {
                snd_info_free_entry(entry);
                return -ENOMEM;
        }
        snd_card_info_entry = entry;

#ifdef MODULE
        entry = snd_info_create_module_entry(THIS_MODULE, "modules", NULL);
        if (entry) {
                entry->c.text.read = snd_card_module_info_read;
                if (snd_info_register(entry) < 0)
                        snd_info_free_entry(entry);
                else
                        snd_card_module_info_entry = entry;
        }
#endif

        return 0;
}

int __exit snd_card_info_done(void)
{
        snd_info_free_entry(snd_card_info_entry);
#ifdef MODULE
        snd_info_free_entry(snd_card_module_info_entry);
#endif
        return 0;
}

#endif /* CONFIG_PROC_FS */

/**
 *  snd_component_add - add a component string
 *  @card: soundcard structure
 *  @component: the component id string
 *
 *  This function adds the component id string to the supported list.
 *  The component can be referred from the alsa-lib.
 *
 *  Returns zero otherwise a negative error code.
 */
  
int snd_component_add(struct snd_card *card, const char *component)
{
        char *ptr;
        int len = strlen(component);

        ptr = strstr(card->components, component);
        if (ptr != NULL) {
                if (ptr[len] == '\0' || ptr[len] == ' ')        /* already there */
                        return 1;
        }
        if (strlen(card->components) + 1 + len + 1 > sizeof(card->components)) {
                snd_BUG();
                return -ENOMEM;
        }
        if (card->components[0] != '\0')
                strcat(card->components, " ");
        strcat(card->components, component);
        return 0;
}

EXPORT_SYMBOL(snd_component_add);

/**
 *  snd_card_file_add - add the file to the file list of the card
 *  @card: soundcard structure
 *  @file: file pointer
 *
 *  This function adds the file to the file linked-list of the card.
 *  This linked-list is used to keep tracking the connection state,
 *  and to avoid the release of busy resources by hotplug.
 *
 *  Returns zero or a negative error code.
 */
int snd_card_file_add(struct snd_card *card, struct file *file)
{
        struct snd_monitor_file *mfile;

        mfile = kmalloc(sizeof(*mfile), GFP_KERNEL);
        if (mfile == NULL)
                return -ENOMEM;
        mfile->file = file;
        mfile->disconnected_f_op = NULL;
        mfile->next = NULL;
        spin_lock(&card->files_lock);
        if (card->shutdown) {
                spin_unlock(&card->files_lock);
                kfree(mfile);
                return -ENODEV;
        }
        mfile->next = card->files;
        card->files = mfile;
        spin_unlock(&card->files_lock);
        return 0;
}

EXPORT_SYMBOL(snd_card_file_add);

/**
 *  snd_card_file_remove - remove the file from the file list
 *  @card: soundcard structure
 *  @file: file pointer
 *
 *  This function removes the file formerly added to the card via
 *  snd_card_file_add() function.
 *  If all files are removed and snd_card_free_when_closed() was
 *  called beforehand, it processes the pending release of
 *  resources.
 *
 *  Returns zero or a negative error code.
 */
int snd_card_file_remove(struct snd_card *card, struct file *file)
{
        struct snd_monitor_file *mfile, *pfile = NULL;
        int last_close = 0;

        spin_lock(&card->files_lock);
        mfile = card->files;
        while (mfile) {
                if (mfile->file == file) {
                        if (pfile)
                                pfile->next = mfile->next;
                        else
                                card->files = mfile->next;
                        break;
                }
                pfile = mfile;
                mfile = mfile->next;
        }
        if (mfile && mfile->disconnected_f_op) {
                fops_put(mfile->disconnected_f_op);
                spin_lock(&shutdown_lock);
                list_del(&mfile->shutdown_list);
                spin_unlock(&shutdown_lock);
        }
        if (card->files == NULL)
                last_close = 1;
        spin_unlock(&card->files_lock);
        if (last_close) {
                wake_up(&card->shutdown_sleep);
                if (card->free_on_last_close)
                        snd_card_do_free(card);
        }
        if (!mfile) {
                snd_printk(KERN_ERR "ALSA card file remove problem (%p)\n", file);
                return -ENOENT;
        }
        kfree(mfile);
        return 0;
}

EXPORT_SYMBOL(snd_card_file_remove);

#ifdef CONFIG_PM
/**
 *  snd_power_wait - wait until the power-state is changed.
 *  @card: soundcard structure
 *  @power_state: expected power state
 *
 *  Waits until the power-state is changed.
 *
 *  Note: the power lock must be active before call.
 */
int snd_power_wait(struct snd_card *card, unsigned int power_state)
{
        wait_queue_t wait;
        int result = 0;

        /* fastpath */
        if (snd_power_get_state(card) == power_state)
                return 0;
        init_waitqueue_entry(&wait, current);
        add_wait_queue(&card->power_sleep, &wait);
        while (1) {
                if (card->shutdown) {
                        result = -ENODEV;
                        break;
                }
                if (snd_power_get_state(card) == power_state)
                        break;
                set_current_state(TASK_UNINTERRUPTIBLE);
                snd_power_unlock(card);
                schedule_timeout(30 * HZ);
                snd_power_lock(card);
        }
        remove_wait_queue(&card->power_sleep, &wait);
        return result;
}

EXPORT_SYMBOL(snd_power_wait);
#endif /* CONFIG_PM */