// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   *  Routines for driver control interface

   *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>

   */

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

  #include <linux/module.h>

  #include <linux/slab.h>
  #include <linux/vmalloc.h>
  #include <linux/time.h>

  #include <linux/mm.h>

  #include <linux/math64.h>

  #include <linux/sched/signal.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 i, err;

  	err = stream_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;

  	for (i = 0; i < SND_CTL_SUBDEV_ITEMS; i++)
  		ctl->preferred_subdevice[i] = -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);

  	snd_card_unref(card);

  	return 0;
  
        __error:
  	module_put(card->module);
        __error2:
  	snd_card_file_remove(card, file);
        __error1:

  	if (card)
  		snd_card_unref(card);

        	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;
  }

  /**
   * snd_ctl_notify - Send notification to user-space for a control change
   * @card: the card to send notification
   * @mask: the event mask, SNDRV_CTL_EVENT_*
   * @id: the ctl element id to send notification
   *
   * This function adds an event record with the given id and mask, appends
   * to the list and wakes up the user-space for notification.  This can be
   * called in the atomic context.
   */

  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;

  	if (card->shutdown)
  		return;

  	read_lock_irqsave(&card->ctl_files_rwlock, flags);

  #if IS_ENABLED(CONFIG_SND_MIXER_OSS)

  	card->mixer_oss_change_count++;
  #endif

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

  		if (!ctl->subscribed)
  			continue;

  		spin_lock(&ctl->read_lock);

  		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 {

  			dev_err(card->dev, "No memory available to allocate event
  ");

  		}
  	_found:
  		wake_up(&ctl->change_sleep);

  		spin_unlock(&ctl->read_lock);

  		kill_fasync(&ctl->fasync, SIGIO, POLL_IN);
  	}

  	read_unlock_irqrestore(&card->ctl_files_rwlock, flags);

  }

  EXPORT_SYMBOL(snd_ctl_notify);

  /**

   * snd_ctl_new - create a new control instance with some elements
   * @kctl: the pointer to store new control instance
   * @count: the number of elements in this control
   * @access: the default access flags for elements in this control
   * @file: given when locking these elements

   *

   * Allocates a memory object for a new control instance. The instance has
   * elements as many as the given number (@count). Each element has given
   * access permissions (@access). Each element is locked when @file is given.

   *

   * Return: 0 on success, error code on failure

   */

  static int snd_ctl_new(struct snd_kcontrol **kctl, unsigned int count,
  		       unsigned int access, struct snd_ctl_file *file)

  {

  	unsigned int idx;

  	if (count == 0 || count > MAX_CONTROL_COUNT)
  		return -EINVAL;

  	*kctl = kzalloc(struct_size(*kctl, vd, count), GFP_KERNEL);

  	if (!*kctl)

  		return -ENOMEM;

  
  	for (idx = 0; idx < count; idx++) {
  		(*kctl)->vd[idx].access = access;
  		(*kctl)->vd[idx].owner = file;
  	}
  	(*kctl)->count = count;
  
  	return 0;

  }
  
  /**
   * 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.
   *

   * Return: 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 count;

  	unsigned int access;

  	int err;

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

  
  	count = ncontrol->count;
  	if (count == 0)
  		count = 1;
  
  	access = ncontrol->access;
  	if (access == 0)
  		access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
  	access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
  		   SNDRV_CTL_ELEM_ACCESS_VOLATILE |
  		   SNDRV_CTL_ELEM_ACCESS_INACTIVE |
  		   SNDRV_CTL_ELEM_ACCESS_TLV_READWRITE |
  		   SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND |

  		   SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK |
  		   SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK);

  
  	err = snd_ctl_new(&kctl, count, access, NULL);
  	if (err < 0)
  		return NULL;
  
  	/* The 'numid' member is decided when calling snd_ctl_add(). */
  	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)

  			pr_warn("ALSA: Control name '%s' truncated to '%s'
  ",

  				ncontrol->name, kctl->id.name);

  	}

  	kctl->id.index = ncontrol->index;
  
  	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 kctl;

  }

  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;

  	/* Make sure that the ids assigned to the control do not wrap around */
  	if (card->last_numid >= UINT_MAX - count)
  		card->last_numid = 0;

  	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 */

  			dev_err(card->dev, "unable to allocate new control numid
  ");

  			return -ENOMEM;
  		}

  	}
  	return 0;
  }

  enum snd_ctl_add_mode {
  	CTL_ADD_EXCLUSIVE, CTL_REPLACE, CTL_ADD_ON_REPLACE,
  };
  
  /* add/replace a new kcontrol object; call with card->controls_rwsem locked */
  static int __snd_ctl_add_replace(struct snd_card *card,
  				 struct snd_kcontrol *kcontrol,
  				 enum snd_ctl_add_mode mode)

  {
  	struct snd_ctl_elem_id id;
  	unsigned int idx;
  	unsigned int count;

  	struct snd_kcontrol *old;
  	int err;

  
  	id = kcontrol->id;
  	if (id.index > UINT_MAX - kcontrol->count)
  		return -EINVAL;

  	old = snd_ctl_find_id(card, &id);
  	if (!old) {
  		if (mode == CTL_REPLACE)
  			return -EINVAL;
  	} else {
  		if (mode == CTL_ADD_EXCLUSIVE) {
  			dev_err(card->dev,
  				"control %i:%i:%i:%s:%i is already present
  ",
  				id.iface, id.device, id.subdevice, id.name,
  				id.index);
  			return -EBUSY;
  		}
  
  		err = snd_ctl_remove(card, old);
  		if (err < 0)
  			return err;

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

  static int snd_ctl_add_replace(struct snd_card *card,
  			       struct snd_kcontrol *kcontrol,
  			       enum snd_ctl_add_mode mode)

  {

  	int err = -EINVAL;

  	if (! kcontrol)

  		return err;

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

  	down_write(&card->controls_rwsem);

  	err = __snd_ctl_add_replace(card, kcontrol, mode);

  	up_write(&card->controls_rwsem);

  	if (err < 0)
  		goto error;

  	return 0;

  
   error:
  	snd_ctl_free_one(kcontrol);
  	return err;

  }

  
  /**
   * 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.
   *
   * It frees automatically the control which cannot be added.
   *
   * Return: Zero if successful, or a negative error code on failure.
   *
   */
  int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
  {
  	return snd_ctl_add_replace(card, kcontrol, CTL_ADD_EXCLUSIVE);
  }

  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.
   *

   * It frees automatically the control which cannot be added or replaced.

   *
   * Return: Zero if successful, or a negative error code on failure.

   */
  int snd_ctl_replace(struct snd_card *card, struct snd_kcontrol *kcontrol,
  		    bool add_on_replace)
  {

  	return snd_ctl_add_replace(card, kcontrol,
  				   add_on_replace ? CTL_ADD_ON_REPLACE : CTL_REPLACE);

  }
  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).

   *
   * Return: 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.

   *
   * Return: 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.

   *
   * Return: 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.

   * The given ID data is filled with full information.

   *

   * Return: 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, 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;
  	}

  	snd_ctl_build_ioff(id, kctl, index_offset);

  	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.
   *

   * Return: 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.
   *

   * The caller must down card->controls_rwsem before calling this function
   * (if the race condition can happen).

   *
   * Return: The pointer of the instance if found, or %NULL if not.
   *

   */

  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.
   *

   * The caller must down card->controls_rwsem before calling this function
   * (if the race condition can happen).

   *
   * Return: The pointer of the instance if found, or %NULL if not.
   *

   */

  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 *list)

  {

  	struct snd_kcontrol *kctl;

  	struct snd_ctl_elem_id id;

  	unsigned int offset, space, jidx;

  	int err = 0;

  	offset = list->offset;
  	space = list->space;

  	down_read(&card->controls_rwsem);

  	list->count = card->controls_count;
  	list->used = 0;

  	if (space > 0) {

  		list_for_each_entry(kctl, &card->controls, list) {
  			if (offset >= kctl->count) {
  				offset -= kctl->count;
  				continue;
  			}
  			for (jidx = offset; jidx < kctl->count; jidx++) {
  				snd_ctl_build_ioff(&id, kctl, jidx);

  				if (copy_to_user(list->pids + list->used, &id,

  						 sizeof(id))) {
  					err = -EFAULT;
  					goto out;
  				}

  				list->used++;

  				if (!--space)
  					goto out;

  			}

  			offset = 0;
  		}

  	}

   out:
  	up_read(&card->controls_rwsem);

  	return err;

  }

  static int snd_ctl_elem_list_user(struct snd_card *card,
  				  struct snd_ctl_elem_list __user *_list)
  {
  	struct snd_ctl_elem_list list;
  	int err;
  
  	if (copy_from_user(&list, _list, sizeof(list)))
  		return -EFAULT;
  	err = snd_ctl_elem_list(card, &list);
  	if (err)
  		return err;
  	if (copy_to_user(_list, &list, sizeof(list)))
  		return -EFAULT;
  
  	return 0;
  }

  /* Check whether the given kctl info is valid */
  static int snd_ctl_check_elem_info(struct snd_card *card,
  				   const struct snd_ctl_elem_info *info)
  {
  	static const unsigned int max_value_counts[] = {
  		[SNDRV_CTL_ELEM_TYPE_BOOLEAN]	= 128,
  		[SNDRV_CTL_ELEM_TYPE_INTEGER]	= 128,
  		[SNDRV_CTL_ELEM_TYPE_ENUMERATED] = 128,
  		[SNDRV_CTL_ELEM_TYPE_BYTES]	= 512,
  		[SNDRV_CTL_ELEM_TYPE_IEC958]	= 1,
  		[SNDRV_CTL_ELEM_TYPE_INTEGER64] = 64,
  	};
  
  	if (info->type < SNDRV_CTL_ELEM_TYPE_BOOLEAN ||
  	    info->type > SNDRV_CTL_ELEM_TYPE_INTEGER64) {
  		if (card)
  			dev_err(card->dev,
  				"control %i:%i:%i:%s:%i: invalid type %d
  ",
  				info->id.iface, info->id.device,
  				info->id.subdevice, info->id.name,
  				info->id.index, info->type);
  		return -EINVAL;
  	}
  	if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED &&
  	    info->value.enumerated.items == 0) {
  		if (card)
  			dev_err(card->dev,
  				"control %i:%i:%i:%s:%i: zero enum items
  ",
  				info->id.iface, info->id.device,
  				info->id.subdevice, info->id.name,
  				info->id.index);
  		return -EINVAL;
  	}
  	if (info->count > max_value_counts[info->type]) {
  		if (card)
  			dev_err(card->dev,
  				"control %i:%i:%i:%s:%i: invalid count %d
  ",
  				info->id.iface, info->id.device,
  				info->id.subdevice, info->id.name,
  				info->id.index, info->count);
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  /* The capacity of struct snd_ctl_elem_value.value.*/
  static const unsigned int value_sizes[] = {
  	[SNDRV_CTL_ELEM_TYPE_BOOLEAN]	= sizeof(long),
  	[SNDRV_CTL_ELEM_TYPE_INTEGER]	= sizeof(long),
  	[SNDRV_CTL_ELEM_TYPE_ENUMERATED] = sizeof(unsigned int),
  	[SNDRV_CTL_ELEM_TYPE_BYTES]	= sizeof(unsigned char),
  	[SNDRV_CTL_ELEM_TYPE_IEC958]	= sizeof(struct snd_aes_iec958),
  	[SNDRV_CTL_ELEM_TYPE_INTEGER64] = sizeof(long long),
  };
  
  #ifdef CONFIG_SND_CTL_VALIDATION
  /* fill the remaining snd_ctl_elem_value data with the given pattern */
  static void fill_remaining_elem_value(struct snd_ctl_elem_value *control,
  				      struct snd_ctl_elem_info *info,
  				      u32 pattern)
  {
  	size_t offset = value_sizes[info->type] * info->count;
  
  	offset = (offset + sizeof(u32) - 1) / sizeof(u32);
  	memset32((u32 *)control->value.bytes.data + offset, pattern,
  		 sizeof(control->value) / sizeof(u32) - offset);
  }
  
  /* check whether the given integer ctl value is valid */
  static int sanity_check_int_value(struct snd_card *card,
  				  const struct snd_ctl_elem_value *control,
  				  const struct snd_ctl_elem_info *info,
  				  int i)
  {
  	long long lval, lmin, lmax, lstep;
  	u64 rem;
  
  	switch (info->type) {
  	default:
  	case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
  		lval = control->value.integer.value[i];
  		lmin = 0;
  		lmax = 1;
  		lstep = 0;
  		break;
  	case SNDRV_CTL_ELEM_TYPE_INTEGER:
  		lval = control->value.integer.value[i];
  		lmin = info->value.integer.min;
  		lmax = info->value.integer.max;
  		lstep = info->value.integer.step;
  		break;
  	case SNDRV_CTL_ELEM_TYPE_INTEGER64:
  		lval = control->value.integer64.value[i];
  		lmin = info->value.integer64.min;
  		lmax = info->value.integer64.max;
  		lstep = info->value.integer64.step;
  		break;
  	case SNDRV_CTL_ELEM_TYPE_ENUMERATED:
  		lval = control->value.enumerated.item[i];
  		lmin = 0;
  		lmax = info->value.enumerated.items - 1;
  		lstep = 0;
  		break;
  	}
  
  	if (lval < lmin || lval > lmax) {
  		dev_err(card->dev,
  			"control %i:%i:%i:%s:%i: value out of range %lld (%lld/%lld) at count %i
  ",
  			control->id.iface, control->id.device,
  			control->id.subdevice, control->id.name,
  			control->id.index, lval, lmin, lmax, i);
  		return -EINVAL;
  	}
  	if (lstep) {
  		div64_u64_rem(lval, lstep, &rem);
  		if (rem) {
  			dev_err(card->dev,
  				"control %i:%i:%i:%s:%i: unaligned value %lld (step %lld) at count %i
  ",
  				control->id.iface, control->id.device,
  				control->id.subdevice, control->id.name,
  				control->id.index, lval, lstep, i);
  			return -EINVAL;
  		}
  	}
  
  	return 0;
  }
  
  /* perform sanity checks to the given snd_ctl_elem_value object */
  static int sanity_check_elem_value(struct snd_card *card,
  				   const struct snd_ctl_elem_value *control,
  				   const struct snd_ctl_elem_info *info,
  				   u32 pattern)
  {
  	size_t offset;

  	int i, ret = 0;

  	u32 *p;
  
  	switch (info->type) {
  	case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
  	case SNDRV_CTL_ELEM_TYPE_INTEGER:
  	case SNDRV_CTL_ELEM_TYPE_INTEGER64:
  	case SNDRV_CTL_ELEM_TYPE_ENUMERATED:
  		for (i = 0; i < info->count; i++) {
  			ret = sanity_check_int_value(card, control, info, i);
  			if (ret < 0)
  				return ret;
  		}
  		break;
  	default:
  		break;
  	}
  
  	/* check whether the remaining area kept untouched */
  	offset = value_sizes[info->type] * info->count;
  	offset = (offset + sizeof(u32) - 1) / sizeof(u32);
  	p = (u32 *)control->value.bytes.data + offset;
  	for (; offset < sizeof(control->value) / sizeof(u32); offset++, p++) {
  		if (*p != pattern) {
  			ret = -EINVAL;
  			break;
  		}
  		*p = 0; /* clear the checked area */
  	}
  
  	return ret;
  }
  #else
  static inline void fill_remaining_elem_value(struct snd_ctl_elem_value *control,
  					     struct snd_ctl_elem_info *info,
  					     u32 pattern)
  {
  }
  
  static inline int sanity_check_elem_value(struct snd_card *card,
  					  struct snd_ctl_elem_value *control,
  					  struct snd_ctl_elem_info *info,
  					  u32 pattern)
  {
  	return 0;
  }
  #endif
  
  static int __snd_ctl_elem_info(struct snd_card *card,
  			       struct snd_kcontrol *kctl,
  			       struct snd_ctl_elem_info *info,
  			       struct snd_ctl_file *ctl)

  {

  	struct snd_kcontrol_volatile *vd;

  	unsigned int index_offset;
  	int result;

  #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;
  		}

  		if (!snd_ctl_skip_validation(info) &&
  		    snd_ctl_check_elem_info(card, info) < 0)
  			result = -EINVAL;

  	}

  	return result;
  }
  
  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;
  	int result;
  
  	down_read(&card->controls_rwsem);
  	kctl = snd_ctl_find_id(card, &info->id);
  	if (kctl == NULL)
  		result = -ENOENT;
  	else
  		result = __snd_ctl_elem_info(card, kctl, info, ctl);

  	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;

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

  	if (result < 0)
  		return result;
  	result = snd_ctl_elem_info(ctl, &info);
  	if (result < 0)
  		return result;

  	/* drop internal access flags */
  	info.access &= ~SNDRV_CTL_ELEM_ACCESS_SKIP_CHECK;

  	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;

  	struct snd_ctl_elem_info info;
  	const u32 pattern = 0xdeadbeef;
  	int ret;

  	kctl = snd_ctl_find_id(card, &control->id);

  	if (kctl == NULL)
  		return -ENOENT;
  
  	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)

  		return -EPERM;
  
  	snd_ctl_build_ioff(&control->id, kctl, index_offset);

  
  #ifdef CONFIG_SND_CTL_VALIDATION
  	/* info is needed only for validation */
  	memset(&info, 0, sizeof(info));
  	info.id = control->id;
  	ret = __snd_ctl_elem_info(card, kctl, &info, NULL);
  	if (ret < 0)
  		return ret;
  #endif
  
  	if (!snd_ctl_skip_validation(&info))
  		fill_remaining_elem_value(control, &info, pattern);
  	ret = kctl->get(kctl, control);
  	if (ret < 0)
  		return ret;
  	if (!snd_ctl_skip_validation(&info) &&
  	    sanity_check_elem_value(card, control, &info, pattern) < 0) {
  		dev_err(card->dev,
  			"control %i:%i:%i:%s:%i: access overflow
  ",
  			control->id.iface, control->id.device,
  			control->id.subdevice, control->id.name,
  			control->id.index);
  		return -EINVAL;
  	}
  	return ret;

  }

  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);

  	result = snd_power_wait(card, SNDRV_CTL_POWER_D0);

  	if (result < 0)
  		goto error;
  
  	down_read(&card->controls_rwsem);
  	result = snd_ctl_elem_read(card, control);
  	up_read(&card->controls_rwsem);
  	if (result < 0)
  		goto error;
  
  	if (copy_to_user(_control, control, sizeof(*control)))
  		result = -EFAULT;
   error:

  	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;

  	kctl = snd_ctl_find_id(card, &control->id);

  	if (kctl == NULL)
  		return -ENOENT;
  
  	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)) {
  		return -EPERM;

  	}

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

  }

  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;

  	result = snd_power_wait(card, SNDRV_CTL_POWER_D0);

  	if (result < 0)
  		goto error;
  
  	down_write(&card->controls_rwsem);
  	result = snd_ctl_elem_write(card, file, control);
  	up_write(&card->controls_rwsem);
  	if (result < 0)
  		goto error;
  
  	if (copy_to_user(_control, control, sizeof(*control)))
  		result = -EFAULT;
   error:

  	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;

  	struct snd_card *card;

  	char *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) */

  };

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

  {
  	struct user_element *ue = kcontrol->private_data;

  	unsigned int offset;

  	offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);

  	*uinfo = ue->info;

  	snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);

  	return 0;
  }

  static int snd_ctl_elem_user_enum_info(struct snd_kcontrol *kcontrol,
  				       struct snd_ctl_elem_info *uinfo)
  {
  	struct user_element *ue = kcontrol->private_data;
  	const char *names;
  	unsigned int item;

  	unsigned int offset;

  
  	item = uinfo->value.enumerated.item;

  	offset = snd_ctl_get_ioff(kcontrol, &uinfo->id);

  	*uinfo = ue->info;

  	snd_ctl_build_ioff(&uinfo->id, kcontrol, offset);

  
  	item = min(item, uinfo->value.enumerated.items - 1);
  	uinfo->value.enumerated.item = item;
  
  	names = ue->priv_data;
  	for (; item > 0; --item)
  		names += strlen(names) + 1;
  	strcpy(uinfo->value.enumerated.name, names);
  
  	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;

  	unsigned int size = ue->elem_data_size;
  	char *src = ue->elem_data +
  			snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;

  	memcpy(&ucontrol->value, src, 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;

  	unsigned int size = ue->elem_data_size;
  	char *dst = ue->elem_data +
  			snd_ctl_get_ioff(kcontrol, &ucontrol->id) * size;

  	change = memcmp(&ucontrol->value, dst, size) != 0;

  	if (change)

  		memcpy(dst, &ucontrol->value, size);

  	return change;
  }

  static int replace_user_tlv(struct snd_kcontrol *kctl, unsigned int __user *buf,
  			    unsigned int size)

  {

  	struct user_element *ue = kctl->private_data;
  	unsigned int *container;

  	struct snd_ctl_elem_id id;

  	unsigned int mask = 0;

  	int i;

  	int change;

  	if (size > 1024 * 128)	/* sane value */
  		return -EINVAL;

  	container = vmemdup_user(buf, size);

  	if (IS_ERR(container))
  		return PTR_ERR(container);

  	change = ue->tlv_data_size != size;
  	if (!change)

  		change = memcmp(ue->tlv_data, container, size) != 0;

  	if (!change) {

  		kvfree(container);

  		return 0;
  	}

  	if (ue->tlv_data == NULL) {
  		/* Now TLV data is available. */
  		for (i = 0; i < kctl->count; ++i)
  			kctl->vd[i].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
  		mask = SNDRV_CTL_EVENT_MASK_INFO;
  	}

  	kvfree(ue->tlv_data);

  	ue->tlv_data = container;
  	ue->tlv_data_size = size;

  	mask |= SNDRV_CTL_EVENT_MASK_TLV;

  	for (i = 0; i < kctl->count; ++i) {
  		snd_ctl_build_ioff(&id, kctl, i);

  		snd_ctl_notify(ue->card, mask, &id);

  	}

  	return change;
  }

  static int read_user_tlv(struct snd_kcontrol *kctl, unsigned int __user *buf,
  			 unsigned int size)
  {
  	struct user_element *ue = kctl->private_data;
  
  	if (ue->tlv_data_size == 0 || ue->tlv_data == NULL)
  		return -ENXIO;
  
  	if (size < ue->tlv_data_size)
  		return -ENOSPC;
  
  	if (copy_to_user(buf, ue->tlv_data, ue->tlv_data_size))
  		return -EFAULT;
  
  	return 0;
  }
  
  static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kctl, int op_flag,
  				 unsigned int size, unsigned int __user *buf)
  {
  	if (op_flag == SNDRV_CTL_TLV_OP_WRITE)
  		return replace_user_tlv(kctl, buf, size);
  	else
  		return read_user_tlv(kctl, buf, size);

  }

  static int snd_ctl_elem_init_enum_names(struct user_element *ue)
  {
  	char *names, *p;
  	size_t buf_len, name_len;
  	unsigned int i;

  	const uintptr_t user_ptrval = ue->info.value.enumerated.names_ptr;

  
  	if (ue->info.value.enumerated.names_length > 64 * 1024)
  		return -EINVAL;

  	names = vmemdup_user((const void __user *)user_ptrval,

  		ue->info.value.enumerated.names_length);
  	if (IS_ERR(names))
  		return PTR_ERR(names);
  
  	/* check that there are enough valid names */
  	buf_len = ue->info.value.enumerated.names_length;
  	p = names;
  	for (i = 0; i < ue->info.value.enumerated.items; ++i) {
  		name_len = strnlen(p, buf_len);
  		if (name_len == 0 || name_len >= 64 || name_len == buf_len) {

  			kvfree(names);

  			return -EINVAL;
  		}
  		p += name_len + 1;
  		buf_len -= name_len + 1;
  	}
  
  	ue->priv_data = names;
  	ue->info.value.enumerated.names_ptr = 0;
  
  	return 0;
  }

  static void snd_ctl_elem_user_free(struct snd_kcontrol *kcontrol)

  {

  	struct user_element *ue = kcontrol->private_data;

  	kvfree(ue->tlv_data);

  	kvfree(ue->priv_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;
  	unsigned int count;

  	unsigned int access;
  	long private_size;
  	struct user_element *ue;

  	unsigned int offset;

  	int err;

  	if (!*info->id.name)
  		return -EINVAL;
  	if (strnlen(info->id.name, sizeof(info->id.name)) >= sizeof(info->id.name))
  		return -EINVAL;

  	/* Delete a control to replace them if needed. */

  	if (replace) {

  		info->id.numid = 0;

  		err = snd_ctl_remove_user_ctl(file, &info->id);
  		if (err)
  			return err;

  	}

  	/*
  	 * The number of userspace controls are counted control by control,
  	 * not element by element.
  	 */
  	if (card->user_ctl_count + 1 > MAX_USER_CONTROLS)

  		return -ENOMEM;

  	/* Check the number of elements for this userspace control. */
  	count = info->owner;
  	if (count == 0)
  		count = 1;
  
  	/* Arrange access permissions if needed. */
  	access = info->access;
  	if (access == 0)
  		access = SNDRV_CTL_ELEM_ACCESS_READWRITE;
  	access &= (SNDRV_CTL_ELEM_ACCESS_READWRITE |
  		   SNDRV_CTL_ELEM_ACCESS_INACTIVE |

  		   SNDRV_CTL_ELEM_ACCESS_TLV_WRITE);
  
  	/* In initial state, nothing is available as TLV container. */
  	if (access & SNDRV_CTL_ELEM_ACCESS_TLV_WRITE)

  		access |= SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;

  	access |= SNDRV_CTL_ELEM_ACCESS_USER;

  	/*
  	 * Check information and calculate the size of data specific to
  	 * this userspace control.
  	 */

  	/* pass NULL to card for suppressing error messages */
  	err = snd_ctl_check_elem_info(NULL, info);
  	if (err < 0)
  		return err;
  	/* user-space control doesn't allow zero-size data */
  	if (info->count < 1)

  		return -EINVAL;

  	private_size = value_sizes[info->type] * info->count;

  
  	/*
  	 * Keep memory object for this userspace control. After passing this
  	 * code block, the instance should be freed by snd_ctl_free_one().
  	 *
  	 * Note that these elements in this control are locked.
  	 */
  	err = snd_ctl_new(&kctl, count, access, file);
  	if (err < 0)
  		return err;

  	memcpy(&kctl->id, &info->id, sizeof(kctl->id));

  	kctl->private_data = kzalloc(sizeof(struct user_element) + private_size * count,

  				     GFP_KERNEL);
  	if (kctl->private_data == NULL) {
  		kfree(kctl);

  		return -ENOMEM;

  	}
  	kctl->private_free = snd_ctl_elem_user_free;
  
  	/* Set private data for this userspace control. */
  	ue = (struct user_element *)kctl->private_data;

  	ue->card = card;

  	ue->info = *info;

  	ue->info.access = 0;

  	ue->elem_data = (char *)ue + sizeof(*ue);
  	ue->elem_data_size = private_size;

  	if (ue->info.type == SNDRV_CTL_ELEM_TYPE_ENUMERATED) {
  		err = snd_ctl_elem_init_enum_names(ue);
  		if (err < 0) {

  			snd_ctl_free_one(kctl);

  			return err;
  		}
  	}

  
  	/* Set callback functions. */
  	if (info->type == SNDRV_CTL_ELEM_TYPE_ENUMERATED)
  		kctl->info = snd_ctl_elem_user_enum_info;
  	else
  		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_WRITE)

  		kctl->tlv.c = snd_ctl_elem_user_tlv;
  
  	/* This function manage to free the instance on failure. */

  	down_write(&card->controls_rwsem);

  	err = __snd_ctl_add_replace(card, kctl, CTL_ADD_EXCLUSIVE);

  	if (err < 0) {
  		snd_ctl_free_one(kctl);
  		goto unlock;
  	}

  	offset = snd_ctl_get_ioff(kctl, &info->id);
  	snd_ctl_build_ioff(&info->id, kctl, offset);
  	/*
  	 * Here we cannot fill any field for the number of elements added by
  	 * this operation because there're no specific fields. The usage of
  	 * 'owner' field for this purpose may cause any bugs to userspace
  	 * applications because the field originally means PID of a process
  	 * which locks the element.
  	 */

  	card->user_ctl_count++;

   unlock:
  	up_write(&card->controls_rwsem);

  	return err;

  }

  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;

  	int err;

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

  	err = snd_ctl_elem_add(file, &info, replace);
  	if (err < 0)
  		return err;
  	if (copy_to_user(_info, &info, sizeof(info))) {
  		snd_ctl_remove_user_ctl(file, &info.id);
  		return -EFAULT;
  	}
  
  	return 0;

  }

  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 call_tlv_handler(struct snd_ctl_file *file, int op_flag,
  			    struct snd_kcontrol *kctl,
  			    struct snd_ctl_elem_id *id,
  			    unsigned int __user *buf, unsigned int size)
  {
  	static const struct {
  		int op;
  		int perm;
  	} pairs[] = {
  		{SNDRV_CTL_TLV_OP_READ,  SNDRV_CTL_ELEM_ACCESS_TLV_READ},
  		{SNDRV_CTL_TLV_OP_WRITE, SNDRV_CTL_ELEM_ACCESS_TLV_WRITE},
  		{SNDRV_CTL_TLV_OP_CMD,   SNDRV_CTL_ELEM_ACCESS_TLV_COMMAND},
  	};
  	struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)];
  	int i;

  
  	/* Check support of the request for this element. */
  	for (i = 0; i < ARRAY_SIZE(pairs); ++i) {
  		if (op_flag == pairs[i].op && (vd->access & pairs[i].perm))
  			break;
  	}
  	if (i == ARRAY_SIZE(pairs))
  		return -ENXIO;
  
  	if (kctl->tlv.c == NULL)
  		return -ENXIO;

  	/* Write and command operations are not allowed for locked element. */
  	if (op_flag != SNDRV_CTL_TLV_OP_READ &&
  	    vd->owner != NULL && vd->owner != file)

  		return -EPERM;

  	return kctl->tlv.c(kctl, op_flag, size, buf);

  }
  
  static int read_tlv_buf(struct snd_kcontrol *kctl, struct snd_ctl_elem_id *id,
  			unsigned int __user *buf, unsigned int size)
  {
  	struct snd_kcontrol_volatile *vd = &kctl->vd[snd_ctl_get_ioff(kctl, id)];
  	unsigned int len;
  
  	if (!(vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_READ))
  		return -ENXIO;
  
  	if (kctl->tlv.p == NULL)
  		return -ENXIO;
  
  	len = sizeof(unsigned int) * 2 + kctl->tlv.p[1];
  	if (size < len)
  		return -ENOMEM;
  
  	if (copy_to_user(buf, kctl->tlv.p, len))
  		return -EFAULT;
  
  	return 0;
  }

  static int snd_ctl_tlv_ioctl(struct snd_ctl_file *file,

  			     struct snd_ctl_tlv __user *buf,

                               int op_flag)

  {

  	struct snd_ctl_tlv header;

  	unsigned int __user *container;

  	unsigned int container_size;

  	struct snd_kcontrol *kctl;

  	struct snd_ctl_elem_id id;

  	struct snd_kcontrol_volatile *vd;

  	if (copy_from_user(&header, buf, sizeof(header)))

  		return -EFAULT;

  
  	/* In design of control core, numerical ID starts at 1. */
  	if (header.numid == 0)

  		return -EINVAL;

  
  	/* At least, container should include type and length fields.  */
  	if (header.length < sizeof(unsigned int) * 2)

  		return -EINVAL;

  	container_size = header.length;
  	container = buf->tlv;

  	kctl = snd_ctl_find_numid(file->card, header.numid);

  	if (kctl == NULL)
  		return -ENOENT;

  	/* Calculate index of the element in this set. */
  	id = kctl->id;
  	snd_ctl_build_ioff(&id, kctl, header.numid - id.numid);
  	vd = &kctl->vd[snd_ctl_get_ioff(kctl, &id)];

  	if (vd->access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {

  		return call_tlv_handler(file, op_flag, kctl, &id, container,
  					container_size);

  	} else {

  		if (op_flag == SNDRV_CTL_TLV_OP_READ) {
  			return read_tlv_buf(kctl, &id, container,
  					    container_size);
  		}

  	}

  	/* Not supported. */
  	return -ENXIO;

  }

  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_user(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:

  		down_read(&ctl->card->controls_rwsem);
  		err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_READ);
  		up_read(&ctl->card->controls_rwsem);
  		return err;

  	case SNDRV_CTL_IOCTL_TLV_WRITE:

  		down_write(&ctl->card->controls_rwsem);
  		err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_WRITE);
  		up_write(&ctl->card->controls_rwsem);
  		return err;

  	case SNDRV_CTL_IOCTL_TLV_COMMAND:

  		down_write(&ctl->card->controls_rwsem);
  		err = snd_ctl_tlv_ioctl(ctl, argp, SNDRV_CTL_TLV_OP_CMD);
  		up_write(&ctl->card->controls_rwsem);
  		return err;

  	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);

  	dev_dbg(card->dev, "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_entry_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 (ctl->card->shutdown)
  				return -ENODEV;

  			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 __poll_t snd_ctl_poll(struct file *file, poll_table * wait)

  {

  	__poll_t 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 |= EPOLLIN | EPOLLRDNORM;

  
  	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;
  }

  /**
   * snd_ctl_register_ioctl - register the device-specific control-ioctls
   * @fcn: ioctl callback function
   *
   * called from each device manager like pcm.c, hwdep.c, etc.
   */

  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

  /**
   * snd_ctl_register_ioctl_compat - register the device-specific 32bit compat
   * control-ioctls
   * @fcn: ioctl callback function
   */

  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;
  }

  /**
   * snd_ctl_unregister_ioctl - de-register the device-specific control-ioctls
   * @fcn: ioctl callback function to unregister
   */

  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

  /**

   * snd_ctl_unregister_ioctl_compat - de-register the device-specific compat
   * 32bit control-ioctls

   * @fcn: ioctl callback function to unregister
   */

  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);

  }

  /* return the preferred subdevice number if already assigned;
   * otherwise return -1
   */
  int snd_ctl_get_preferred_subdevice(struct snd_card *card, int type)
  {
  	struct snd_ctl_file *kctl;
  	int subdevice = -1;

  	unsigned long flags;

  	read_lock_irqsave(&card->ctl_files_rwlock, flags);

  	list_for_each_entry(kctl, &card->ctl_files, list) {
  		if (kctl->pid == task_pid(current)) {
  			subdevice = kctl->preferred_subdevice[type];
  			if (subdevice != -1)
  				break;
  		}
  	}

  	read_unlock_irqrestore(&card->ctl_files_rwlock, flags);

  	return subdevice;
  }
  EXPORT_SYMBOL_GPL(snd_ctl_get_preferred_subdevice);

  /*
   * 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;

  	return snd_register_device(SNDRV_DEVICE_TYPE_CONTROL, card, -1,
  				   &snd_ctl_f_ops, card, &card->ctl_dev);

  }
  
  /*
   * 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;

  	unsigned long flags;

  	read_lock_irqsave(&card->ctl_files_rwlock, flags);

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

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

  	read_unlock_irqrestore(&card->ctl_files_rwlock, flags);