/*
   *  Routines for driver control interface

   *  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/threads.h>
  #include <linux/interrupt.h>

  #include <linux/slab.h>
  #include <linux/vmalloc.h>
  #include <linux/time.h>
  #include <sound/core.h>
  #include <sound/minors.h>
  #include <sound/info.h>
  #include <sound/control.h>
  
  /* max number of user-defined controls */
  #define MAX_USER_CONTROLS	32

  #define MAX_CONTROL_COUNT	1028

  struct snd_kctl_ioctl {

  	struct list_head list;		/* list of all ioctls */
  	snd_kctl_ioctl_func_t fioctl;

  };

  
  static DECLARE_RWSEM(snd_ioctl_rwsem);
  static LIST_HEAD(snd_control_ioctls);
  #ifdef CONFIG_COMPAT
  static LIST_HEAD(snd_control_compat_ioctls);
  #endif
  
  static int snd_ctl_open(struct inode *inode, struct file *file)
  {

  	unsigned long flags;

  	struct snd_card *card;
  	struct snd_ctl_file *ctl;

  	int err;

  	err = nonseekable_open(inode, file);
  	if (err < 0)
  		return err;

  	card = snd_lookup_minor_data(iminor(inode), SNDRV_DEVICE_TYPE_CONTROL);

  	if (!card) {
  		err = -ENODEV;
  		goto __error1;
  	}
  	err = snd_card_file_add(card, file);
  	if (err < 0) {
  		err = -ENODEV;
  		goto __error1;
  	}
  	if (!try_module_get(card->module)) {
  		err = -EFAULT;
  		goto __error2;
  	}

  	ctl = kzalloc(sizeof(*ctl), GFP_KERNEL);

  	if (ctl == NULL) {
  		err = -ENOMEM;
  		goto __error;
  	}
  	INIT_LIST_HEAD(&ctl->events);
  	init_waitqueue_head(&ctl->change_sleep);
  	spin_lock_init(&ctl->read_lock);
  	ctl->card = card;

  	ctl->prefer_pcm_subdevice = -1;
  	ctl->prefer_rawmidi_subdevice = -1;

  	ctl->pid = get_pid(task_pid(current));

  	file->private_data = ctl;
  	write_lock_irqsave(&card->ctl_files_rwlock, flags);
  	list_add_tail(&ctl->list, &card->ctl_files);
  	write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
  	return 0;
  
        __error:
  	module_put(card->module);
        __error2:
  	snd_card_file_remove(card, file);
        __error1:
        	return err;
  }

  static void snd_ctl_empty_read_queue(struct snd_ctl_file * ctl)

  {

  	unsigned long flags;

  	struct snd_kctl_event *cread;

  	spin_lock_irqsave(&ctl->read_lock, flags);

  	while (!list_empty(&ctl->events)) {
  		cread = snd_kctl_event(ctl->events.next);
  		list_del(&cread->list);
  		kfree(cread);
  	}

  	spin_unlock_irqrestore(&ctl->read_lock, flags);

  }
  
  static int snd_ctl_release(struct inode *inode, struct file *file)
  {
  	unsigned long flags;

  	struct snd_card *card;
  	struct snd_ctl_file *ctl;
  	struct snd_kcontrol *control;

  	unsigned int idx;
  
  	ctl = file->private_data;

  	file->private_data = NULL;
  	card = ctl->card;
  	write_lock_irqsave(&card->ctl_files_rwlock, flags);
  	list_del(&ctl->list);
  	write_unlock_irqrestore(&card->ctl_files_rwlock, flags);
  	down_write(&card->controls_rwsem);

  	list_for_each_entry(control, &card->controls, list)

  		for (idx = 0; idx < control->count; idx++)
  			if (control->vd[idx].owner == ctl)
  				control->vd[idx].owner = NULL;

  	up_write(&card->controls_rwsem);
  	snd_ctl_empty_read_queue(ctl);

  	put_pid(ctl->pid);

  	kfree(ctl);
  	module_put(card->module);
  	snd_card_file_remove(card, file);
  	return 0;
  }

  void snd_ctl_notify(struct snd_card *card, unsigned int mask,
  		    struct snd_ctl_elem_id *id)

  {
  	unsigned long flags;

  	struct snd_ctl_file *ctl;
  	struct snd_kctl_event *ev;

  	if (snd_BUG_ON(!card || !id))
  		return;

  	read_lock(&card->ctl_files_rwlock);
  #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE)
  	card->mixer_oss_change_count++;
  #endif

  	list_for_each_entry(ctl, &card->ctl_files, list) {

  		if (!ctl->subscribed)
  			continue;
  		spin_lock_irqsave(&ctl->read_lock, flags);

  		list_for_each_entry(ev, &ctl->events, list) {

  			if (ev->id.numid == id->numid) {
  				ev->mask |= mask;
  				goto _found;
  			}
  		}

  		ev = kzalloc(sizeof(*ev), GFP_ATOMIC);

  		if (ev) {
  			ev->id = *id;
  			ev->mask = mask;
  			list_add_tail(&ev->list, &ctl->events);
  		} else {
  			snd_printk(KERN_ERR "No memory available to allocate event
  ");
  		}
  	_found:
  		wake_up(&ctl->change_sleep);
  		spin_unlock_irqrestore(&ctl->read_lock, flags);
  		kill_fasync(&ctl->fasync, SIGIO, POLL_IN);
  	}
  	read_unlock(&card->ctl_files_rwlock);
  }

  EXPORT_SYMBOL(snd_ctl_notify);

  /**
   * snd_ctl_new - create a control instance from the template
   * @control: the control template
   * @access: the default control access
   *

   * Allocates a new struct snd_kcontrol instance and copies the given template 

   * to the new instance. It does not copy volatile data (access).
   *
   * Returns the pointer of the new instance, or NULL on failure.
   */

  static struct snd_kcontrol *snd_ctl_new(struct snd_kcontrol *control,
  					unsigned int access)

  {

  	struct snd_kcontrol *kctl;

  	unsigned int idx;
  	

  	if (snd_BUG_ON(!control || !control->count))
  		return NULL;

  
  	if (control->count > MAX_CONTROL_COUNT)
  		return NULL;

  	kctl = kzalloc(sizeof(*kctl) + sizeof(struct snd_kcontrol_volatile) * control->count, GFP_KERNEL);

  	if (kctl == NULL) {
  		snd_printk(KERN_ERR "Cannot allocate control instance
  ");

  		return NULL;

  	}

  	*kctl = *control;
  	for (idx = 0; idx < kctl->count; idx++)
  		kctl->vd[idx].access = access;
  	return kctl;
  }
  
  /**
   * snd_ctl_new1 - create a control instance from the template
   * @ncontrol: the initialization record
   * @private_data: the private data to set
   *

   * Allocates a new struct snd_kcontrol instance and initialize from the given 

   * template.  When the access field of ncontrol is 0, it's assumed as
   * READWRITE access. When the count field is 0, it's assumes as one.
   *
   * Returns the pointer of the newly generated instance, or NULL on failure.
   */

  struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new *ncontrol,
  				  void *private_data)

  {

  	struct snd_kcontrol kctl;

  	unsigned int access;
  	

  	if (snd_BUG_ON(!ncontrol || !ncontrol->info))
  		return NULL;

  	memset(&kctl, 0, sizeof(kctl));
  	kctl.id.iface = ncontrol->iface;
  	kctl.id.device = ncontrol->device;
  	kctl.id.subdevice = ncontrol->subdevice;

  	if (ncontrol->name) {

  		strlcpy(kctl.id.name, ncontrol->name, sizeof(kctl.id.name));

  		if (strcmp(ncontrol->name, kctl.id.name) != 0)
  			snd_printk(KERN_WARNING
  				   "Control name '%s' truncated to '%s'
  ",
  				   ncontrol->name, kctl.id.name);
  	}

  	kctl.id.index = ncontrol->index;
  	kctl.count = ncontrol->count ? ncontrol->count : 1;
  	access = ncontrol->access == 0 ? SNDRV_CTL_ELEM_ACCESS_READWRITE :

  		 (ncontrol->access & (SNDRV_CTL_ELEM_ACCESS_READWRITE|
  				      SNDRV_CTL_ELEM_ACCESS_INACTIVE|

  				      SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE|
  				      SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND|
  				      SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK));

  	kctl.info = ncontrol->info;
  	kctl.get = ncontrol->get;
  	kctl.put = ncontrol->put;

  	kctl.tlv.p = ncontrol->tlv.p;

  	kctl.private_value = ncontrol->private_value;
  	kctl.private_data = private_data;
  	return snd_ctl_new(&kctl, access);
  }

  EXPORT_SYMBOL(snd_ctl_new1);

  /**
   * snd_ctl_free_one - release the control instance
   * @kcontrol: the control instance
   *
   * Releases the control instance created via snd_ctl_new()
   * or snd_ctl_new1().
   * Don't call this after the control was added to the card.
   */

  void snd_ctl_free_one(struct snd_kcontrol *kcontrol)

  {
  	if (kcontrol) {
  		if (kcontrol->private_free)
  			kcontrol->private_free(kcontrol);
  		kfree(kcontrol);
  	}
  }

  EXPORT_SYMBOL(snd_ctl_free_one);

  static bool snd_ctl_remove_numid_conflict(struct snd_card *card,
  					  unsigned int count)

  {

  	struct snd_kcontrol *kctl;

  	list_for_each_entry(kctl, &card->controls, list) {

  		if (kctl->id.numid < card->last_numid + 1 + count &&

  		    kctl->id.numid + kctl->count > card->last_numid + 1) {
  		    	card->last_numid = kctl->id.numid + kctl->count - 1;
  			return true;
  		}

  	}

  	return false;

  }

  static int snd_ctl_find_hole(struct snd_card *card, unsigned int count)

  {

  	unsigned int iter = 100000;

  	while (snd_ctl_remove_numid_conflict(card, count)) {

  		if (--iter == 0) {
  			/* this situation is very unlikely */
  			snd_printk(KERN_ERR "unable to allocate new control numid
  ");
  			return -ENOMEM;
  		}

  	}
  	return 0;
  }
  
  /**
   * snd_ctl_add - add the control instance to the card
   * @card: the card instance
   * @kcontrol: the control instance to add
   *
   * Adds the control instance created via snd_ctl_new() or
   * snd_ctl_new1() to the given card. Assigns also an unique
   * numid used for fast search.
   *
   * Returns zero if successful, or a negative error code on failure.
   *
   * It frees automatically the control which cannot be added.
   */

  int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)

  {

  	struct snd_ctl_elem_id id;

  	unsigned int idx;

  	int err = -EINVAL;

  	if (! kcontrol)

  		return err;

  	if (snd_BUG_ON(!card || !kcontrol->info))
  		goto error;

  	id = kcontrol->id;
  	down_write(&card->controls_rwsem);
  	if (snd_ctl_find_id(card, &id)) {
  		up_write(&card->controls_rwsem);

  		snd_printd(KERN_ERR "control %i:%i:%i:%s:%i is already present
  ",
  					id.iface,
  					id.device,
  					id.subdevice,
  					id.name,
  					id.index);

  		err = -EBUSY;
  		goto error;

  	}
  	if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
  		up_write(&card->controls_rwsem);

  		err = -ENOMEM;
  		goto error;

  	}
  	list_add_tail(&kcontrol->list, &card->controls);
  	card->controls_count += kcontrol->count;
  	kcontrol->id.numid = card->last_numid + 1;
  	card->last_numid += kcontrol->count;
  	up_write(&card->controls_rwsem);
  	for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
  		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
  	return 0;

  
   error:
  	snd_ctl_free_one(kcontrol);
  	return err;

  }

  EXPORT_SYMBOL(snd_ctl_add);

  /**

   * snd_ctl_replace - replace the control instance of the card
   * @card: the card instance
   * @kcontrol: the control instance to replace
   * @add_on_replace: add the control if not already added
   *
   * Replaces the given control.  If the given control does not exist
   * and the add_on_replace flag is set, the control is added.  If the
   * control exists, it is destroyed first.
   *
   * Returns zero if successful, or a negative error code on failure.
   *
   * It frees automatically the control which cannot be added or replaced.
   */
  int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
  		    bool add_on_replace)
  {
  	struct snd_ctl_elem_id id;
  	unsigned int idx;
  	struct snd_kcontrol *old;
  	int ret;
  
  	if (!kcontrol)
  		return -EINVAL;
  	if (snd_BUG_ON(!card || !kcontrol->info)) {
  		ret = -EINVAL;
  		goto error;
  	}
  	id = kcontrol->id;
  	down_write(&card->controls_rwsem);
  	old = snd_ctl_find_id(card, &id);
  	if (!old) {
  		if (add_on_replace)
  			goto add;
  		up_write(&card->controls_rwsem);
  		ret = -EINVAL;
  		goto error;
  	}
  	ret = snd_ctl_remove(card, old);
  	if (ret < 0) {
  		up_write(&card->controls_rwsem);
  		goto error;
  	}
  add:
  	if (snd_ctl_find_hole(card, kcontrol->count) < 0) {
  		up_write(&card->controls_rwsem);
  		ret = -ENOMEM;
  		goto error;
  	}
  	list_add_tail(&kcontrol->list, &card->controls);
  	card->controls_count += kcontrol->count;
  	kcontrol->id.numid = card->last_numid + 1;
  	card->last_numid += kcontrol->count;
  	up_write(&card->controls_rwsem);
  	for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
  		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_ADD, &id);
  	return 0;
  
  error:
  	snd_ctl_free_one(kcontrol);
  	return ret;
  }
  EXPORT_SYMBOL(snd_ctl_replace);
  
  /**

   * snd_ctl_remove - remove the control from the card and release it
   * @card: the card instance
   * @kcontrol: the control instance to remove
   *
   * Removes the control from the card and then releases the instance.
   * You don't need to call snd_ctl_free_one(). You must be in
   * the write lock - down_write(&card->controls_rwsem).
   * 
   * Returns 0 if successful, or a negative error code on failure.
   */

  int snd_ctl_remove(struct snd_card *card, struct snd_kcontrol *kcontrol)

  {

  	struct snd_ctl_elem_id id;

  	unsigned int idx;

  	if (snd_BUG_ON(!card || !kcontrol))
  		return -EINVAL;

  	list_del(&kcontrol->list);
  	card->controls_count -= kcontrol->count;
  	id = kcontrol->id;
  	for (idx = 0; idx < kcontrol->count; idx++, id.index++, id.numid++)
  		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_REMOVE, &id);
  	snd_ctl_free_one(kcontrol);
  	return 0;
  }

  EXPORT_SYMBOL(snd_ctl_remove);

  /**
   * snd_ctl_remove_id - remove the control of the given id and release it
   * @card: the card instance
   * @id: the control id to remove
   *
   * Finds the control instance with the given id, removes it from the
   * card list and releases it.
   * 
   * Returns 0 if successful, or a negative error code on failure.
   */

  int snd_ctl_remove_id(struct snd_card *card, struct snd_ctl_elem_id *id)

  {

  	struct snd_kcontrol *kctl;

  	int ret;
  
  	down_write(&card->controls_rwsem);
  	kctl = snd_ctl_find_id(card, id);
  	if (kctl == NULL) {
  		up_write(&card->controls_rwsem);
  		return -ENOENT;
  	}
  	ret = snd_ctl_remove(card, kctl);
  	up_write(&card->controls_rwsem);
  	return ret;
  }

  EXPORT_SYMBOL(snd_ctl_remove_id);

  /**

   * snd_ctl_remove_user_ctl - remove and release the unlocked user control

   * @file: active control handle
   * @id: the control id to remove
   *
   * Finds the control instance with the given id, removes it from the
   * card list and releases it.
   * 
   * Returns 0 if successful, or a negative error code on failure.
   */

  static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
  				   struct snd_ctl_elem_id *id)

  {

  	struct snd_card *card = file->card;
  	struct snd_kcontrol *kctl;

  	int idx, ret;
  
  	down_write(&card->controls_rwsem);
  	kctl = snd_ctl_find_id(card, id);
  	if (kctl == NULL) {

  		ret = -ENOENT;
  		goto error;

  	}

  	if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER)) {
  		ret = -EINVAL;
  		goto error;
  	}

  	for (idx = 0; idx < kctl->count; idx++)
  		if (kctl->vd[idx].owner != NULL && kctl->vd[idx].owner != file) {

  			ret = -EBUSY;
  			goto error;

  		}
  	ret = snd_ctl_remove(card, kctl);

  	if (ret < 0)
  		goto error;
  	card->user_ctl_count--;

  error:

  	up_write(&card->controls_rwsem);
  	return ret;
  }
  
  /**

   * snd_ctl_activate_id - activate/inactivate the control of the given id
   * @card: the card instance
   * @id: the control id to activate/inactivate
   * @active: non-zero to activate
   *
   * Finds the control instance with the given id, and activate or
   * inactivate the control together with notification, if changed.
   *
   * Returns 0 if unchanged, 1 if changed, or a negative error code on failure.
   */
  int snd_ctl_activate_id(struct snd_card *card, struct snd_ctl_elem_id *id,
  			int active)
  {
  	struct snd_kcontrol *kctl;
  	struct snd_kcontrol_volatile *vd;
  	unsigned int index_offset;
  	int ret;
  
  	down_write(&card->controls_rwsem);
  	kctl = snd_ctl_find_id(card, id);
  	if (kctl == NULL) {
  		ret = -ENOENT;
  		goto unlock;
  	}
  	index_offset = snd_ctl_get_ioff(kctl, &kctl->id);
  	vd = &kctl->vd[index_offset];
  	ret = 0;
  	if (active) {
  		if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE))
  			goto unlock;
  		vd->access &= ~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
  	} else {
  		if (vd->access & SNDRV_CTL_ELEM_ACCESS_INACTIVE)
  			goto unlock;
  		vd->access |= SNDRV_CTL_ELEM_ACCESS_INACTIVE;
  	}
  	ret = 1;
   unlock:
  	up_write(&card->controls_rwsem);
  	if (ret > 0)
  		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO, id);
  	return ret;
  }
  EXPORT_SYMBOL_GPL(snd_ctl_activate_id);
  
  /**

   * snd_ctl_rename_id - replace the id of a control on the card
   * @card: the card instance
   * @src_id: the old id
   * @dst_id: the new id
   *
   * Finds the control with the old id from the card, and replaces the
   * id with the new one.
   *
   * Returns zero if successful, or a negative error code on failure.
   */

  int snd_ctl_rename_id(struct snd_card *card, struct snd_ctl_elem_id *src_id,
  		      struct snd_ctl_elem_id *dst_id)

  {

  	struct snd_kcontrol *kctl;

  
  	down_write(&card->controls_rwsem);
  	kctl = snd_ctl_find_id(card, src_id);
  	if (kctl == NULL) {
  		up_write(&card->controls_rwsem);
  		return -ENOENT;
  	}
  	kctl->id = *dst_id;
  	kctl->id.numid = card->last_numid + 1;
  	card->last_numid += kctl->count;
  	up_write(&card->controls_rwsem);
  	return 0;
  }

  EXPORT_SYMBOL(snd_ctl_rename_id);

  /**
   * snd_ctl_find_numid - find the control instance with the given number-id
   * @card: the card instance
   * @numid: the number-id to search
   *
   * Finds the control instance with the given number-id from the card.
   *
   * Returns the pointer of the instance if found, or NULL if not.
   *
   * The caller must down card->controls_rwsem before calling this function
   * (if the race condition can happen).
   */

  struct snd_kcontrol *snd_ctl_find_numid(struct snd_card *card, unsigned int numid)

  {

  	struct snd_kcontrol *kctl;

  	if (snd_BUG_ON(!card || !numid))
  		return NULL;

  	list_for_each_entry(kctl, &card->controls, list) {

  		if (kctl->id.numid <= numid && kctl->id.numid + kctl->count > numid)
  			return kctl;
  	}
  	return NULL;
  }

  EXPORT_SYMBOL(snd_ctl_find_numid);

  /**
   * snd_ctl_find_id - find the control instance with the given id
   * @card: the card instance
   * @id: the id to search
   *
   * Finds the control instance with the given id from the card.
   *
   * Returns the pointer of the instance if found, or NULL if not.
   *
   * The caller must down card->controls_rwsem before calling this function
   * (if the race condition can happen).
   */

  struct snd_kcontrol *snd_ctl_find_id(struct snd_card *card,
  				     struct snd_ctl_elem_id *id)

  {

  	struct snd_kcontrol *kctl;

  	if (snd_BUG_ON(!card || !id))
  		return NULL;

  	if (id->numid != 0)
  		return snd_ctl_find_numid(card, id->numid);

  	list_for_each_entry(kctl, &card->controls, list) {

  		if (kctl->id.iface != id->iface)
  			continue;
  		if (kctl->id.device != id->device)
  			continue;
  		if (kctl->id.subdevice != id->subdevice)
  			continue;
  		if (strncmp(kctl->id.name, id->name, sizeof(kctl->id.name)))
  			continue;
  		if (kctl->id.index > id->index)
  			continue;
  		if (kctl->id.index + kctl->count <= id->index)
  			continue;
  		return kctl;
  	}
  	return NULL;
  }

  EXPORT_SYMBOL(snd_ctl_find_id);

  static int snd_ctl_card_info(struct snd_card *card, struct snd_ctl_file * ctl,

  			     unsigned int cmd, void __user *arg)
  {

  	struct snd_ctl_card_info *info;

  	info = kzalloc(sizeof(*info), GFP_KERNEL);

  	if (! info)
  		return -ENOMEM;
  	down_read(&snd_ioctl_rwsem);
  	info->card = card->number;
  	strlcpy(info->id, card->id, sizeof(info->id));
  	strlcpy(info->driver, card->driver, sizeof(info->driver));
  	strlcpy(info->name, card->shortname, sizeof(info->name));
  	strlcpy(info->longname, card->longname, sizeof(info->longname));
  	strlcpy(info->mixername, card->mixername, sizeof(info->mixername));
  	strlcpy(info->components, card->components, sizeof(info->components));
  	up_read(&snd_ioctl_rwsem);

  	if (copy_to_user(arg, info, sizeof(struct snd_ctl_card_info))) {

  		kfree(info);
  		return -EFAULT;
  	}
  	kfree(info);
  	return 0;
  }

  static int snd_ctl_elem_list(struct snd_card *card,
  			     struct snd_ctl_elem_list __user *_list)

  {
  	struct list_head *plist;

  	struct snd_ctl_elem_list list;
  	struct snd_kcontrol *kctl;
  	struct snd_ctl_elem_id *dst, *id;

  	unsigned int offset, space, jidx;

  	
  	if (copy_from_user(&list, _list, sizeof(list)))
  		return -EFAULT;
  	offset = list.offset;
  	space = list.space;

  	/* try limit maximum space */
  	if (space > 16384)
  		return -ENOMEM;
  	if (space > 0) {
  		/* allocate temporary buffer for atomic operation */

  		dst = vmalloc(space * sizeof(struct snd_ctl_elem_id));

  		if (dst == NULL)
  			return -ENOMEM;
  		down_read(&card->controls_rwsem);
  		list.count = card->controls_count;
  		plist = card->controls.next;
  		while (plist != &card->controls) {
  			if (offset == 0)
  				break;
  			kctl = snd_kcontrol(plist);
  			if (offset < kctl->count)
  				break;
  			offset -= kctl->count;
  			plist = plist->next;
  		}
  		list.used = 0;
  		id = dst;
  		while (space > 0 && plist != &card->controls) {
  			kctl = snd_kcontrol(plist);
  			for (jidx = offset; space > 0 && jidx < kctl->count; jidx++) {
  				snd_ctl_build_ioff(id, kctl, jidx);
  				id++;
  				space--;
  				list.used++;
  			}
  			plist = plist->next;
  			offset = 0;
  		}
  		up_read(&card->controls_rwsem);

  		if (list.used > 0 &&
  		    copy_to_user(list.pids, dst,
  				 list.used * sizeof(struct snd_ctl_elem_id))) {

  			vfree(dst);
  			return -EFAULT;
  		}
  		vfree(dst);
  	} else {
  		down_read(&card->controls_rwsem);
  		list.count = card->controls_count;
  		up_read(&card->controls_rwsem);
  	}
  	if (copy_to_user(_list, &list, sizeof(list)))
  		return -EFAULT;
  	return 0;
  }

  static int snd_ctl_elem_info(struct snd_ctl_file *ctl,
  			     struct snd_ctl_elem_info *info)

  {

  	struct snd_card *card = ctl->card;
  	struct snd_kcontrol *kctl;
  	struct snd_kcontrol_volatile *vd;

  	unsigned int index_offset;
  	int result;
  	
  	down_read(&card->controls_rwsem);
  	kctl = snd_ctl_find_id(card, &info->id);
  	if (kctl == NULL) {
  		up_read(&card->controls_rwsem);
  		return -ENOENT;
  	}
  #ifdef CONFIG_SND_DEBUG
  	info->access = 0;
  #endif
  	result = kctl->info(kctl, info);
  	if (result >= 0) {

  		snd_BUG_ON(info->access);

  		index_offset = snd_ctl_get_ioff(kctl, &info->id);
  		vd = &kctl->vd[index_offset];
  		snd_ctl_build_ioff(&info->id, kctl, index_offset);
  		info->access = vd->access;
  		if (vd->owner) {
  			info->access |= SNDRV_CTL_ELEM_ACCESS_LOCK;
  			if (vd->owner == ctl)
  				info->access |= SNDRV_CTL_ELEM_ACCESS_OWNER;

  			info->owner = pid_vnr(vd->owner->pid);

  		} else {
  			info->owner = -1;
  		}
  	}
  	up_read(&card->controls_rwsem);
  	return result;
  }

  static int snd_ctl_elem_info_user(struct snd_ctl_file *ctl,
  				  struct snd_ctl_elem_info __user *_info)

  {

  	struct snd_ctl_elem_info info;

  	int result;
  
  	if (copy_from_user(&info, _info, sizeof(info)))
  		return -EFAULT;

  	snd_power_lock(ctl->card);

  	result = snd_power_wait(ctl->card, SNDRV_CTL_POWER_D0);

  	if (result >= 0)
  		result = snd_ctl_elem_info(ctl, &info);
  	snd_power_unlock(ctl->card);

  	if (result >= 0)
  		if (copy_to_user(_info, &info, sizeof(info)))
  			return -EFAULT;
  	return result;
  }

  static int snd_ctl_elem_read(struct snd_card *card,
  			     struct snd_ctl_elem_value *control)

  {

  	struct snd_kcontrol *kctl;
  	struct snd_kcontrol_volatile *vd;

  	unsigned int index_offset;

  	int result;

  
  	down_read(&card->controls_rwsem);
  	kctl = snd_ctl_find_id(card, &control->id);
  	if (kctl == NULL) {
  		result = -ENOENT;
  	} else {
  		index_offset = snd_ctl_get_ioff(kctl, &control->id);
  		vd = &kctl->vd[index_offset];

  		if ((vd->access & SNDRV_CTL_ELEM_ACCESS_READ) &&
  		    kctl->get != NULL) {
  			snd_ctl_build_ioff(&control->id, kctl, index_offset);
  			result = kctl->get(kctl, control);
  		} else
  			result = -EPERM;

  	}
  	up_read(&card->controls_rwsem);
  	return result;
  }

  static int snd_ctl_elem_read_user(struct snd_card *card,
  				  struct snd_ctl_elem_value __user *_control)

  {

  	struct snd_ctl_elem_value *control;

  	int result;

  
  	control = memdup_user(_control, sizeof(*control));
  	if (IS_ERR(control))
  		return PTR_ERR(control);

  	snd_power_lock(card);

  	result = snd_power_wait(card, SNDRV_CTL_POWER_D0);

  	if (result >= 0)
  		result = snd_ctl_elem_read(card, control);
  	snd_power_unlock(card);

  	if (result >= 0)
  		if (copy_to_user(_control, control, sizeof(*control)))
  			result = -EFAULT;
  	kfree(control);
  	return result;
  }

  static int snd_ctl_elem_write(struct snd_card *card, struct snd_ctl_file *file,
  			      struct snd_ctl_elem_value *control)

  {

  	struct snd_kcontrol *kctl;
  	struct snd_kcontrol_volatile *vd;

  	unsigned int index_offset;

  	int result;

  
  	down_read(&card->controls_rwsem);
  	kctl = snd_ctl_find_id(card, &control->id);
  	if (kctl == NULL) {
  		result = -ENOENT;
  	} else {
  		index_offset = snd_ctl_get_ioff(kctl, &control->id);
  		vd = &kctl->vd[index_offset];

  		if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_WRITE) ||
  		    kctl->put == NULL ||
  		    (file && vd->owner && vd->owner != file)) {
  			result = -EPERM;

  		} else {

  			snd_ctl_build_ioff(&control->id, kctl, index_offset);
  			result = kctl->put(kctl, control);
  		}
  		if (result > 0) {
  			up_read(&card->controls_rwsem);
  			snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
  				       &control->id);
  			return 0;

  		}
  	}
  	up_read(&card->controls_rwsem);
  	return result;
  }

  static int snd_ctl_elem_write_user(struct snd_ctl_file *file,
  				   struct snd_ctl_elem_value __user *_control)

  {

  	struct snd_ctl_elem_value *control;

  	struct snd_card *card;

  	int result;

  	control = memdup_user(_control, sizeof(*control));
  	if (IS_ERR(control))
  		return PTR_ERR(control);

  	card = file->card;
  	snd_power_lock(card);

  	result = snd_power_wait(card, SNDRV_CTL_POWER_D0);

  	if (result >= 0)
  		result = snd_ctl_elem_write(card, file, control);
  	snd_power_unlock(card);

  	if (result >= 0)
  		if (copy_to_user(_control, control, sizeof(*control)))
  			result = -EFAULT;
  	kfree(control);
  	return result;
  }

  static int snd_ctl_elem_lock(struct snd_ctl_file *file,
  			     struct snd_ctl_elem_id __user *_id)

  {

  	struct snd_card *card = file->card;
  	struct snd_ctl_elem_id id;
  	struct snd_kcontrol *kctl;
  	struct snd_kcontrol_volatile *vd;

  	int result;
  	
  	if (copy_from_user(&id, _id, sizeof(id)))
  		return -EFAULT;
  	down_write(&card->controls_rwsem);
  	kctl = snd_ctl_find_id(card, &id);
  	if (kctl == NULL) {
  		result = -ENOENT;
  	} else {
  		vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
  		if (vd->owner != NULL)
  			result = -EBUSY;
  		else {
  			vd->owner = file;

  			result = 0;
  		}
  	}
  	up_write(&card->controls_rwsem);
  	return result;
  }

  static int snd_ctl_elem_unlock(struct snd_ctl_file *file,
  			       struct snd_ctl_elem_id __user *_id)

  {

  	struct snd_card *card = file->card;
  	struct snd_ctl_elem_id id;
  	struct snd_kcontrol *kctl;
  	struct snd_kcontrol_volatile *vd;

  	int result;
  	
  	if (copy_from_user(&id, _id, sizeof(id)))
  		return -EFAULT;
  	down_write(&card->controls_rwsem);
  	kctl = snd_ctl_find_id(card, &id);
  	if (kctl == NULL) {
  		result = -ENOENT;
  	} else {
  		vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];
  		if (vd->owner == NULL)
  			result = -EINVAL;
  		else if (vd->owner != file)
  			result = -EPERM;
  		else {
  			vd->owner = NULL;

  			result = 0;
  		}
  	}
  	up_write(&card->controls_rwsem);
  	return result;
  }
  
  struct user_element {

  	struct snd_ctl_elem_info info;

  	void *elem_data;		/* element data */
  	unsigned long elem_data_size;	/* size of element data in bytes */

  	void *tlv_data;			/* TLV data */
  	unsigned long tlv_data_size;	/* TLV data size */

  	void *priv_data;		/* private data (like strings for enumerated type) */
  	unsigned long priv_data_size;	/* size of private data in bytes */
  };

  static int snd_ctl_elem_user_info(struct snd_kcontrol *kcontrol,
  				  struct snd_ctl_elem_info *uinfo)

  {
  	struct user_element *ue = kcontrol->private_data;
  
  	*uinfo = ue->info;
  	return 0;
  }

  static int snd_ctl_elem_user_get(struct snd_kcontrol *kcontrol,
  				 struct snd_ctl_elem_value *ucontrol)

  {
  	struct user_element *ue = kcontrol->private_data;
  
  	memcpy(&ucontrol->value, ue->elem_data, ue->elem_data_size);
  	return 0;
  }

  static int snd_ctl_elem_user_put(struct snd_kcontrol *kcontrol,
  				 struct snd_ctl_elem_value *ucontrol)

  {
  	int change;
  	struct user_element *ue = kcontrol->private_data;
  	
  	change = memcmp(&ucontrol->value, ue->elem_data, ue->elem_data_size) != 0;
  	if (change)
  		memcpy(ue->elem_data, &ucontrol->value, ue->elem_data_size);
  	return change;
  }

  static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol,
  				 int op_flag,
  				 unsigned int size,
  				 unsigned int __user *tlv)
  {
  	struct user_element *ue = kcontrol->private_data;
  	int change = 0;
  	void *new_data;
  
  	if (op_flag > 0) {
  		if (size > 1024 * 128)	/* sane value */
  			return -EINVAL;

  
  		new_data = memdup_user(tlv, size);
  		if (IS_ERR(new_data))
  			return PTR_ERR(new_data);

  		change = ue->tlv_data_size != size;
  		if (!change)
  			change = memcmp(ue->tlv_data, new_data, size);
  		kfree(ue->tlv_data);
  		ue->tlv_data = new_data;
  		ue->tlv_data_size = size;
  	} else {

  		if (! ue->tlv_data_size || ! ue->tlv_data)
  			return -ENXIO;

  		if (size < ue->tlv_data_size)
  			return -ENOSPC;
  		if (copy_to_user(tlv, ue->tlv_data, ue->tlv_data_size))
  			return -EFAULT;
  	}
  	return change;
  }

  static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)

  {

  	struct user_element *ue = kcontrol->private_data;
  	if (ue->tlv_data)
  		kfree(ue->tlv_data);
  	kfree(ue);

  }

  static int snd_ctl_elem_add(struct snd_ctl_file *file,
  			    struct snd_ctl_elem_info *info, int replace)

  {

  	struct snd_card *card = file->card;
  	struct snd_kcontrol kctl, *_kctl;

  	unsigned int access;
  	long private_size;
  	struct user_element *ue;
  	int idx, err;
  	
  	if (card->user_ctl_count >= MAX_USER_CONTROLS)
  		return -ENOMEM;

  	if (info->count < 1)

  		return -EINVAL;
  	access = info->access == 0 ? SNDRV_CTL_ELEM_ACCESS_READWRITE :

  		(info->access & (SNDRV_CTL_ELEM_ACCESS_READWRITE|

  				 SNDRV_CTL_ELEM_ACCESS_INACTIVE|
  				 SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE));

  	info->id.numid = 0;
  	memset(&kctl, 0, sizeof(kctl));
  	down_write(&card->controls_rwsem);
  	_kctl = snd_ctl_find_id(card, &info->id);
  	err = 0;
  	if (_kctl) {
  		if (replace)
  			err = snd_ctl_remove(card, _kctl);
  		else
  			err = -EBUSY;
  	} else {
  		if (replace)
  			err = -ENOENT;
  	}
  	up_write(&card->controls_rwsem);
  	if (err < 0)
  		return err;
  	memcpy(&kctl.id, &info->id, sizeof(info->id));
  	kctl.count = info->owner ? info->owner : 1;
  	access |= SNDRV_CTL_ELEM_ACCESS_USER;
  	kctl.info = snd_ctl_elem_user_info;
  	if (access & SNDRV_CTL_ELEM_ACCESS_READ)
  		kctl.get = snd_ctl_elem_user_get;
  	if (access & SNDRV_CTL_ELEM_ACCESS_WRITE)
  		kctl.put = snd_ctl_elem_user_put;

  	if (access & SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE) {
  		kctl.tlv.c = snd_ctl_elem_user_tlv;
  		access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
  	}

  	switch (info->type) {
  	case SNDRV_CTL_ELEM_TYPE_BOOLEAN:

  	case SNDRV_CTL_ELEM_TYPE_INTEGER:
  		private_size = sizeof(long);
  		if (info->count > 128)
  			return -EINVAL;
  		break;
  	case SNDRV_CTL_ELEM_TYPE_INTEGER64:
  		private_size = sizeof(long long);
  		if (info->count > 64)
  			return -EINVAL;
  		break;
  	case SNDRV_CTL_ELEM_TYPE_BYTES:
  		private_size = sizeof(unsigned char);
  		if (info->count > 512)
  			return -EINVAL;
  		break;
  	case SNDRV_CTL_ELEM_TYPE_IEC958:

  		private_size = sizeof(struct snd_aes_iec958);

  		if (info->count != 1)
  			return -EINVAL;
  		break;
  	default:
  		return -EINVAL;
  	}
  	private_size *= info->count;

  	ue = kzalloc(sizeof(struct user_element) + private_size, GFP_KERNEL);

  	if (ue == NULL)
  		return -ENOMEM;
  	ue->info = *info;

  	ue->info.access = 0;

  	ue->elem_data = (char *)ue + sizeof(*ue);
  	ue->elem_data_size = private_size;
  	kctl.private_free = snd_ctl_elem_user_free;
  	_kctl = snd_ctl_new(&kctl, access);
  	if (_kctl == NULL) {

  		kfree(ue);

  		return -ENOMEM;
  	}
  	_kctl->private_data = ue;
  	for (idx = 0; idx < _kctl->count; idx++)
  		_kctl->vd[idx].owner = file;
  	err = snd_ctl_add(card, _kctl);

  	if (err < 0)

  		return err;

  
  	down_write(&card->controls_rwsem);
  	card->user_ctl_count++;
  	up_write(&card->controls_rwsem);
  
  	return 0;
  }

  static int snd_ctl_elem_add_user(struct snd_ctl_file *file,
  				 struct snd_ctl_elem_info __user *_info, int replace)

  {

  	struct snd_ctl_elem_info info;

  	if (copy_from_user(&info, _info, sizeof(info)))
  		return -EFAULT;
  	return snd_ctl_elem_add(file, &info, replace);
  }

  static int snd_ctl_elem_remove(struct snd_ctl_file *file,
  			       struct snd_ctl_elem_id __user *_id)

  {

  	struct snd_ctl_elem_id id;

  
  	if (copy_from_user(&id, _id, sizeof(id)))
  		return -EFAULT;

  	return snd_ctl_remove_user_ctl(file, &id);

  }

  static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)

  {
  	int subscribe;
  	if (get_user(subscribe, ptr))
  		return -EFAULT;
  	if (subscribe < 0) {
  		subscribe = file->subscribed;
  		if (put_user(subscribe, ptr))
  			return -EFAULT;
  		return 0;
  	}
  	if (subscribe) {
  		file->subscribed = 1;
  		return 0;
  	} else if (file->subscribed) {
  		snd_ctl_empty_read_queue(file);
  		file->subscribed = 0;
  	}
  	return 0;
  }

  static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,
                               struct snd_ctl_tlv __user *_tlv,
                               int op_flag)

  {

  	struct snd_card *card = file->card;

  	struct snd_ctl_tlv tlv;
  	struct snd_kcontrol *kctl;

  	struct snd_kcontrol_volatile *vd;

  	unsigned int len;
  	int err = 0;
  
  	if (copy_from_user(&tlv, _tlv, sizeof(tlv)))
  		return -EFAULT;

  	if (tlv.length < sizeof(unsigned int) * 2)

  		return -EINVAL;
  	down_read(&card->controls_rwsem);
  	kctl = snd_ctl_find_numid(card, tlv.numid);
  	if (kctl == NULL) {
  		err = -ENOENT;
  		goto __kctl_end;
  	}
  	if (kctl->tlv.p == NULL) {
  		err = -ENXIO;
  		goto __kctl_end;
  	}
  	vd = &kctl->vd[tlv.numid - kctl->id.numid];
  	if ((op_flag == 0 && (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ) == 0) ||
  	    (op_flag > 0 && (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE) == 0) ||
  	    (op_flag < 0 && (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND) == 0)) {
  	    	err = -ENXIO;
  	    	goto __kctl_end;
  	}
  	if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {

  		if (vd->owner != NULL && vd->owner != file) {

  			err = -EPERM;
  			goto __kctl_end;
  		}
  		err = kctl->tlv.c(kctl, op_flag, tlv.length, _tlv->tlv); 
  		if (err > 0) {
  			up_read(&card->controls_rwsem);
  			snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_TLV, &kctl->id);
  			return 0;
  		}
  	} else {
  		if (op_flag) {
  			err = -ENXIO;
  			goto __kctl_end;
  		}
  		len = kctl->tlv.p[1] + 2 * sizeof(unsigned int);
  		if (tlv.length < len) {
  			err = -ENOMEM;
  			goto __kctl_end;
  		}
  		if (copy_to_user(_tlv->tlv, kctl->tlv.p, len))
  			err = -EFAULT;
  	}

        __kctl_end:

  	up_read(&card->controls_rwsem);
  	return err;

  }

  static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  {

  	struct snd_ctl_file *ctl;
  	struct snd_card *card;

  	struct snd_kctl_ioctl *p;

  	void __user *argp = (void __user *)arg;
  	int __user *ip = argp;
  	int err;
  
  	ctl = file->private_data;
  	card = ctl->card;

  	if (snd_BUG_ON(!card))
  		return -ENXIO;

  	switch (cmd) {
  	case SNDRV_CTL_IOCTL_PVERSION:
  		return put_user(SNDRV_CTL_VERSION, ip) ? -EFAULT : 0;
  	case SNDRV_CTL_IOCTL_CARD_INFO:
  		return snd_ctl_card_info(card, ctl, cmd, argp);
  	case SNDRV_CTL_IOCTL_ELEM_LIST:

  		return snd_ctl_elem_list(card, argp);

  	case SNDRV_CTL_IOCTL_ELEM_INFO:
  		return snd_ctl_elem_info_user(ctl, argp);
  	case SNDRV_CTL_IOCTL_ELEM_READ:

  		return snd_ctl_elem_read_user(card, argp);

  	case SNDRV_CTL_IOCTL_ELEM_WRITE:
  		return snd_ctl_elem_write_user(ctl, argp);
  	case SNDRV_CTL_IOCTL_ELEM_LOCK:
  		return snd_ctl_elem_lock(ctl, argp);
  	case SNDRV_CTL_IOCTL_ELEM_UNLOCK:
  		return snd_ctl_elem_unlock(ctl, argp);
  	case SNDRV_CTL_IOCTL_ELEM_ADD:
  		return snd_ctl_elem_add_user(ctl, argp, 0);
  	case SNDRV_CTL_IOCTL_ELEM_REPLACE:
  		return snd_ctl_elem_add_user(ctl, argp, 1);
  	case SNDRV_CTL_IOCTL_ELEM_REMOVE:
  		return snd_ctl_elem_remove(ctl, argp);
  	case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
  		return snd_ctl_subscribe_events(ctl, ip);

  	case SNDRV_CTL_IOCTL_TLV_READ:
  		return snd_ctl_tlv_ioctl(ctl, argp, 0);
  	case SNDRV_CTL_IOCTL_TLV_WRITE:
  		return snd_ctl_tlv_ioctl(ctl, argp, 1);
  	case SNDRV_CTL_IOCTL_TLV_COMMAND:
  		return snd_ctl_tlv_ioctl(ctl, argp, -1);

  	case SNDRV_CTL_IOCTL_POWER:

  		return -ENOPROTOOPT;

  	case SNDRV_CTL_IOCTL_POWER_STATE:
  #ifdef CONFIG_PM
  		return put_user(card->power_state, ip) ? -EFAULT : 0;
  #else
  		return put_user(SNDRV_CTL_POWER_D0, ip) ? -EFAULT : 0;
  #endif
  	}
  	down_read(&snd_ioctl_rwsem);

  	list_for_each_entry(p, &snd_control_ioctls, list) {

  		err = p->fioctl(card, ctl, cmd, arg);
  		if (err != -ENOIOCTLCMD) {
  			up_read(&snd_ioctl_rwsem);
  			return err;
  		}
  	}
  	up_read(&snd_ioctl_rwsem);

  	snd_printdd("unknown ioctl = 0x%x
  ", cmd);

  	return -ENOTTY;
  }

  static ssize_t snd_ctl_read(struct file *file, char __user *buffer,
  			    size_t count, loff_t * offset)

  {

  	struct snd_ctl_file *ctl;

  	int err = 0;
  	ssize_t result = 0;
  
  	ctl = file->private_data;

  	if (snd_BUG_ON(!ctl || !ctl->card))
  		return -ENXIO;

  	if (!ctl->subscribed)
  		return -EBADFD;

  	if (count < sizeof(struct snd_ctl_event))

  		return -EINVAL;
  	spin_lock_irq(&ctl->read_lock);

  	while (count >= sizeof(struct snd_ctl_event)) {
  		struct snd_ctl_event ev;
  		struct snd_kctl_event *kev;

  		while (list_empty(&ctl->events)) {
  			wait_queue_t wait;
  			if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
  				err = -EAGAIN;
  				goto __end_lock;
  			}
  			init_waitqueue_entry(&wait, current);
  			add_wait_queue(&ctl->change_sleep, &wait);
  			set_current_state(TASK_INTERRUPTIBLE);
  			spin_unlock_irq(&ctl->read_lock);
  			schedule();
  			remove_wait_queue(&ctl->change_sleep, &wait);
  			if (signal_pending(current))

  				return -ERESTARTSYS;

  			spin_lock_irq(&ctl->read_lock);
  		}
  		kev = snd_kctl_event(ctl->events.next);
  		ev.type = SNDRV_CTL_EVENT_ELEM;
  		ev.data.elem.mask = kev->mask;
  		ev.data.elem.id = kev->id;
  		list_del(&kev->list);
  		spin_unlock_irq(&ctl->read_lock);
  		kfree(kev);

  		if (copy_to_user(buffer, &ev, sizeof(struct snd_ctl_event))) {

  			err = -EFAULT;
  			goto __end;
  		}
  		spin_lock_irq(&ctl->read_lock);

  		buffer += sizeof(struct snd_ctl_event);
  		count -= sizeof(struct snd_ctl_event);
  		result += sizeof(struct snd_ctl_event);

  	}
        __end_lock:
  	spin_unlock_irq(&ctl->read_lock);
        __end:
        	return result > 0 ? result : err;
  }
  
  static unsigned int snd_ctl_poll(struct file *file, poll_table * wait)
  {
  	unsigned int mask;

  	struct snd_ctl_file *ctl;

  
  	ctl = file->private_data;
  	if (!ctl->subscribed)
  		return 0;
  	poll_wait(file, &ctl->change_sleep, wait);
  
  	mask = 0;
  	if (!list_empty(&ctl->events))
  		mask |= POLLIN | POLLRDNORM;
  
  	return mask;
  }
  
  /*
   * register the device-specific control-ioctls.
   * called from each device manager like pcm.c, hwdep.c, etc.
   */
  static int _snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn, struct list_head *lists)
  {

  	struct snd_kctl_ioctl *pn;

  	pn = kzalloc(sizeof(struct snd_kctl_ioctl), GFP_KERNEL);

  	if (pn == NULL)
  		return -ENOMEM;
  	pn->fioctl = fcn;
  	down_write(&snd_ioctl_rwsem);
  	list_add_tail(&pn->list, lists);
  	up_write(&snd_ioctl_rwsem);
  	return 0;
  }
  
  int snd_ctl_register_ioctl(snd_kctl_ioctl_func_t fcn)
  {
  	return _snd_ctl_register_ioctl(fcn, &snd_control_ioctls);
  }

  EXPORT_SYMBOL(snd_ctl_register_ioctl);

  #ifdef CONFIG_COMPAT
  int snd_ctl_register_ioctl_compat(snd_kctl_ioctl_func_t fcn)
  {
  	return _snd_ctl_register_ioctl(fcn, &snd_control_compat_ioctls);
  }

  
  EXPORT_SYMBOL(snd_ctl_register_ioctl_compat);

  #endif
  
  /*
   * de-register the device-specific control-ioctls.
   */

  static int _snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn,
  				     struct list_head *lists)

  {

  	struct snd_kctl_ioctl *p;

  	if (snd_BUG_ON(!fcn))
  		return -EINVAL;

  	down_write(&snd_ioctl_rwsem);

  	list_for_each_entry(p, lists, list) {

  		if (p->fioctl == fcn) {
  			list_del(&p->list);
  			up_write(&snd_ioctl_rwsem);
  			kfree(p);
  			return 0;
  		}
  	}
  	up_write(&snd_ioctl_rwsem);
  	snd_BUG();
  	return -EINVAL;
  }
  
  int snd_ctl_unregister_ioctl(snd_kctl_ioctl_func_t fcn)
  {
  	return _snd_ctl_unregister_ioctl(fcn, &snd_control_ioctls);
  }

  EXPORT_SYMBOL(snd_ctl_unregister_ioctl);

  #ifdef CONFIG_COMPAT
  int snd_ctl_unregister_ioctl_compat(snd_kctl_ioctl_func_t fcn)
  {
  	return _snd_ctl_unregister_ioctl(fcn, &snd_control_compat_ioctls);
  }

  EXPORT_SYMBOL(snd_ctl_unregister_ioctl_compat);

  #endif
  
  static int snd_ctl_fasync(int fd, struct file * file, int on)
  {

  	struct snd_ctl_file *ctl;

  	ctl = file->private_data;

  	return fasync_helper(fd, file, on, &ctl->fasync);

  }
  
  /*
   * ioctl32 compat
   */
  #ifdef CONFIG_COMPAT
  #include "control_compat.c"
  #else
  #define snd_ctl_ioctl_compat	NULL
  #endif
  
  /*
   *  INIT PART
   */

  static const struct file_operations snd_ctl_f_ops =

  {
  	.owner =	THIS_MODULE,
  	.read =		snd_ctl_read,
  	.open =		snd_ctl_open,
  	.release =	snd_ctl_release,

  	.llseek =	no_llseek,

  	.poll =		snd_ctl_poll,
  	.unlocked_ioctl =	snd_ctl_ioctl,
  	.compat_ioctl =	snd_ctl_ioctl_compat,
  	.fasync =	snd_ctl_fasync,
  };

  /*
   * registration of the control device
   */

  static int snd_ctl_dev_register(struct snd_device *device)

  {

  	struct snd_card *card = device->device_data;

  	int err, cardnum;
  	char name[16];

  	if (snd_BUG_ON(!card))
  		return -ENXIO;

  	cardnum = card->number;

  	if (snd_BUG_ON(cardnum < 0 || cardnum >= SNDRV_CARDS))
  		return -ENXIO;

  	sprintf(name, "controlC%i", cardnum);

  	if ((err = snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
  				       &snd_ctl_f_ops, card, name)) < 0)

  		return err;
  	return 0;
  }
  
  /*
   * disconnection of the control device
   */

  static int snd_ctl_dev_disconnect(struct snd_device *device)

  {

  	struct snd_card *card = device->device_data;

  	struct snd_ctl_file *ctl;

  	int err, cardnum;

  	if (snd_BUG_ON(!card))
  		return -ENXIO;

  	cardnum = card->number;

  	if (snd_BUG_ON(cardnum < 0 || cardnum >= SNDRV_CARDS))
  		return -ENXIO;

  	read_lock(&card->ctl_files_rwlock);

  	list_for_each_entry(ctl, &card->ctl_files, list) {

  		wake_up(&ctl->change_sleep);
  		kill_fasync(&ctl->fasync, SIGIO, POLL_ERR);
  	}

  	read_unlock(&card->ctl_files_rwlock);

  
  	if ((err = snd_unregister_device(SNDRV_DEVICE_TYPE_CONTROL,
  					 card, -1)) < 0)
  		return err;

  	return 0;
  }
  
  /*
   * free all controls
   */

  static int snd_ctl_dev_free(struct snd_device *device)

  {

  	struct snd_card *card = device->device_data;
  	struct snd_kcontrol *control;

  
  	down_write(&card->controls_rwsem);
  	while (!list_empty(&card->controls)) {
  		control = snd_kcontrol(card->controls.next);
  		snd_ctl_remove(card, control);
  	}
  	up_write(&card->controls_rwsem);
  	return 0;
  }
  
  /*

   * create control core:
   * called from init.c
   */

  int snd_ctl_create(struct snd_card *card)

  {

  	static struct snd_device_ops ops = {

  		.dev_free = snd_ctl_dev_free,
  		.dev_register =	snd_ctl_dev_register,
  		.dev_disconnect = snd_ctl_dev_disconnect,

  	};

  	if (snd_BUG_ON(!card))
  		return -ENXIO;

  	return snd_device_new(card, SNDRV_DEV_CONTROL, card, &ops);
  }

  
  /*

   * Frequently used control callbacks/helpers

   */
  int snd_ctl_boolean_mono_info(struct snd_kcontrol *kcontrol,
  			      struct snd_ctl_elem_info *uinfo)
  {
  	uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
  	uinfo->count = 1;
  	uinfo->value.integer.min = 0;
  	uinfo->value.integer.max = 1;
  	return 0;
  }
  
  EXPORT_SYMBOL(snd_ctl_boolean_mono_info);
  
  int snd_ctl_boolean_stereo_info(struct snd_kcontrol *kcontrol,
  				struct snd_ctl_elem_info *uinfo)
  {
  	uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
  	uinfo->count = 2;
  	uinfo->value.integer.min = 0;
  	uinfo->value.integer.max = 1;
  	return 0;
  }
  
  EXPORT_SYMBOL(snd_ctl_boolean_stereo_info);

  
  /**
   * snd_ctl_enum_info - fills the info structure for an enumerated control
   * @info: the structure to be filled
   * @channels: the number of the control's channels; often one
   * @items: the number of control values; also the size of @names
   * @names: an array containing the names of all control values
   *
   * Sets all required fields in @info to their appropriate values.
   * If the control's accessibility is not the default (readable and writable),
   * the caller has to fill @info->access.
   */
  int snd_ctl_enum_info(struct snd_ctl_elem_info *info, unsigned int channels,
  		      unsigned int items, const char *const names[])
  {
  	info->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
  	info->count = channels;
  	info->value.enumerated.items = items;
  	if (info->value.enumerated.item >= items)
  		info->value.enumerated.item = items - 1;
  	strlcpy(info->value.enumerated.name,
  		names[info->value.enumerated.item],
  		sizeof(info->value.enumerated.name));
  	return 0;
  }
  EXPORT_SYMBOL(snd_ctl_enum_info);