// SPDX-License-Identifier: GPL-2.0-only

  /*

   * Virtual master and follower controls

   *
   *  Copyright (c) 2008 by Takashi Iwai <tiwai@suse.de>

   */
  
  #include <linux/slab.h>

  #include <linux/export.h>

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

  #include <sound/tlv.h>

  
  /*
   * a subset of information returned via ctl info callback
   */
  struct link_ctl_info {

  	snd_ctl_elem_type_t type; /* value type */

  	int count;		/* item count */
  	int min_val, max_val;	/* min, max values */
  };
  
  /*

   * link master - this contains a list of follower controls that are

   * identical types, i.e. info returns the same value type and value
   * ranges, but may have different number of counts.
   *
   * The master control is so far only mono volume/switch for simplicity.

   * The same value will be applied to all followers.

   */
  struct link_master {

  	struct list_head followers;

  	struct link_ctl_info info;
  	int val;		/* the master value */

  	unsigned int tlv[4];

  	void (*hook)(void *private_data, int);
  	void *hook_private_data;

  };
  
  /*

   * link follower - this contains a follower control element

   *

   * It fakes the control callbacks with additional attenuation by the
   * master control.  A follower may have either one or two channels.

   */

  struct link_follower {

  	struct list_head list;
  	struct link_master *master;
  	struct link_ctl_info info;
  	int vals[2];		/* current values */

  	unsigned int flags;

  	struct snd_kcontrol *kctl; /* original kcontrol pointer */

  	struct snd_kcontrol follower; /* the copy of original control entry */

  };

  static int follower_update(struct link_follower *follower)

  {
  	struct snd_ctl_elem_value *uctl;
  	int err, ch;

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

  	if (!uctl)
  		return -ENOMEM;

  	uctl->id = follower->follower.id;
  	err = follower->follower.get(&follower->follower, uctl);

  	if (err < 0)
  		goto error;

  	for (ch = 0; ch < follower->info.count; ch++)
  		follower->vals[ch] = uctl->value.integer.value[ch];

   error:

  	kfree(uctl);

  	return err < 0 ? err : 0;

  }

  /* get the follower ctl info and save the initial values */
  static int follower_init(struct link_follower *follower)

  {
  	struct snd_ctl_elem_info *uinfo;

  	int err;

  	if (follower->info.count) {

  		/* already initialized */

  		if (follower->flags & SND_CTL_FOLLOWER_NEED_UPDATE)
  			return follower_update(follower);

  		return 0;
  	}

  
  	uinfo = kmalloc(sizeof(*uinfo), GFP_KERNEL);
  	if (!uinfo)
  		return -ENOMEM;

  	uinfo->id = follower->follower.id;
  	err = follower->follower.info(&follower->follower, uinfo);

  	if (err < 0) {
  		kfree(uinfo);
  		return err;
  	}

  	follower->info.type = uinfo->type;
  	follower->info.count = uinfo->count;
  	if (follower->info.count > 2  ||
  	    (follower->info.type != SNDRV_CTL_ELEM_TYPE_INTEGER &&
  	     follower->info.type != SNDRV_CTL_ELEM_TYPE_BOOLEAN)) {
  		pr_err("ALSA: vmaster: invalid follower element
  ");

  		kfree(uinfo);
  		return -EINVAL;
  	}

  	follower->info.min_val = uinfo->value.integer.min;
  	follower->info.max_val = uinfo->value.integer.max;

  	kfree(uinfo);

  	return follower_update(follower);

  }
  
  /* initialize master volume */
  static int master_init(struct link_master *master)
  {

  	struct link_follower *follower;

  
  	if (master->info.count)
  		return 0; /* already initialized */

  	list_for_each_entry(follower, &master->followers, list) {
  		int err = follower_init(follower);

  		if (err < 0)
  			return err;

  		master->info = follower->info;

  		master->info.count = 1; /* always mono */
  		/* set full volume as default (= no attenuation) */
  		master->val = master->info.max_val;

  		if (master->hook)
  			master->hook(master->hook_private_data, master->val);
  		return 1;

  	}
  	return -ENOENT;
  }

  static int follower_get_val(struct link_follower *follower,
  			    struct snd_ctl_elem_value *ucontrol)

  {
  	int err, ch;

  	err = follower_init(follower);

  	if (err < 0)
  		return err;

  	for (ch = 0; ch < follower->info.count; ch++)
  		ucontrol->value.integer.value[ch] = follower->vals[ch];

  	return 0;
  }

  static int follower_put_val(struct link_follower *follower,
  			    struct snd_ctl_elem_value *ucontrol)

  {
  	int err, ch, vol;

  	err = master_init(follower->master);

  	if (err < 0)
  		return err;

  	switch (follower->info.type) {

  	case SNDRV_CTL_ELEM_TYPE_BOOLEAN:

  		for (ch = 0; ch < follower->info.count; ch++)

  			ucontrol->value.integer.value[ch] &=

  				!!follower->master->val;

  		break;
  	case SNDRV_CTL_ELEM_TYPE_INTEGER:

  		for (ch = 0; ch < follower->info.count; ch++) {

  			/* max master volume is supposed to be 0 dB */
  			vol = ucontrol->value.integer.value[ch];

  			vol += follower->master->val - follower->master->info.max_val;
  			if (vol < follower->info.min_val)
  				vol = follower->info.min_val;
  			else if (vol > follower->info.max_val)
  				vol = follower->info.max_val;

  			ucontrol->value.integer.value[ch] = vol;
  		}
  		break;
  	}

  	return follower->follower.put(&follower->follower, ucontrol);

  }
  
  /*

   * ctl callbacks for followers

   */

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

  {

  	struct link_follower *follower = snd_kcontrol_chip(kcontrol);
  	return follower->follower.info(&follower->follower, uinfo);

  }

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

  {

  	struct link_follower *follower = snd_kcontrol_chip(kcontrol);
  	return follower_get_val(follower, ucontrol);

  }

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

  {

  	struct link_follower *follower = snd_kcontrol_chip(kcontrol);

  	int err, ch, changed = 0;

  	err = follower_init(follower);

  	if (err < 0)
  		return err;

  	for (ch = 0; ch < follower->info.count; ch++) {
  		if (follower->vals[ch] != ucontrol->value.integer.value[ch]) {

  			changed = 1;

  			follower->vals[ch] = ucontrol->value.integer.value[ch];

  		}
  	}
  	if (!changed)
  		return 0;

  	err = follower_put_val(follower, ucontrol);

  	if (err < 0)
  		return err;
  	return 1;

  }

  static int follower_tlv_cmd(struct snd_kcontrol *kcontrol,
  			    int op_flag, unsigned int size,
  			    unsigned int __user *tlv)

  {

  	struct link_follower *follower = snd_kcontrol_chip(kcontrol);

  	/* FIXME: this assumes that the max volume is 0 dB */

  	return follower->follower.tlv.c(&follower->follower, op_flag, size, tlv);

  }

  static void follower_free(struct snd_kcontrol *kcontrol)

  {

  	struct link_follower *follower = snd_kcontrol_chip(kcontrol);
  	if (follower->follower.private_free)
  		follower->follower.private_free(&follower->follower);
  	if (follower->master)
  		list_del(&follower->list);
  	kfree(follower);

  }
  
  /*

   * Add a follower control to the group with the given master control

   *

   * All followers must be the same type (returning the same information

   * via info callback).  The function doesn't check it, so it's your

   * responsibility.
   *
   * Also, some additional limitations:
   * - at most two channels
   * - logarithmic volume control (dB level), no linear volume
   * - master can only attenuate the volume, no gain
   */

  int _snd_ctl_add_follower(struct snd_kcontrol *master,
  			  struct snd_kcontrol *follower,
  			  unsigned int flags)

  {
  	struct link_master *master_link = snd_kcontrol_chip(master);

  	struct link_follower *srec;

  	srec = kzalloc(struct_size(srec, follower.vd, follower->count),

  		       GFP_KERNEL);

  	if (!srec)
  		return -ENOMEM;

  	srec->kctl = follower;
  	srec->follower = *follower;
  	memcpy(srec->follower.vd, follower->vd, follower->count * sizeof(*follower->vd));

  	srec->master = master_link;

  	srec->flags = flags;

  
  	/* override callbacks */

  	follower->info = follower_info;
  	follower->get = follower_get;
  	follower->put = follower_put;
  	if (follower->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK)
  		follower->tlv.c = follower_tlv_cmd;
  	follower->private_data = srec;
  	follower->private_free = follower_free;
  
  	list_add_tail(&srec->list, &master_link->followers);

  	return 0;
  }

  EXPORT_SYMBOL(_snd_ctl_add_follower);

  /*
   * ctl callbacks for master controls
   */
  static int master_info(struct snd_kcontrol *kcontrol,
  		      struct snd_ctl_elem_info *uinfo)
  {
  	struct link_master *master = snd_kcontrol_chip(kcontrol);
  	int ret;
  
  	ret = master_init(master);
  	if (ret < 0)
  		return ret;
  	uinfo->type = master->info.type;
  	uinfo->count = master->info.count;
  	uinfo->value.integer.min = master->info.min_val;
  	uinfo->value.integer.max = master->info.max_val;
  	return 0;
  }
  
  static int master_get(struct snd_kcontrol *kcontrol,
  		      struct snd_ctl_elem_value *ucontrol)
  {
  	struct link_master *master = snd_kcontrol_chip(kcontrol);
  	int err = master_init(master);
  	if (err < 0)
  		return err;
  	ucontrol->value.integer.value[0] = master->val;
  	return 0;
  }

  static int sync_followers(struct link_master *master, int old_val, int new_val)

  {

  	struct link_follower *follower;

  	struct snd_ctl_elem_value *uval;

  
  	uval = kmalloc(sizeof(*uval), GFP_KERNEL);
  	if (!uval)
  		return -ENOMEM;

  	list_for_each_entry(follower, &master->followers, list) {

  		master->val = old_val;

  		uval->id = follower->follower.id;
  		follower_get_val(follower, uval);

  		master->val = new_val;

  		follower_put_val(follower, uval);

  	}
  	kfree(uval);

  	return 0;
  }
  
  static int master_put(struct snd_kcontrol *kcontrol,
  		      struct snd_ctl_elem_value *ucontrol)
  {
  	struct link_master *master = snd_kcontrol_chip(kcontrol);
  	int err, new_val, old_val;
  	bool first_init;
  
  	err = master_init(master);
  	if (err < 0)
  		return err;
  	first_init = err;
  	old_val = master->val;
  	new_val = ucontrol->value.integer.value[0];
  	if (new_val == old_val)
  		return 0;

  	err = sync_followers(master, old_val, new_val);

  	if (err < 0)
  		return err;

  	if (master->hook && !first_init)

  		master->hook(master->hook_private_data, master->val);

  	return 1;
  }
  
  static void master_free(struct snd_kcontrol *kcontrol)
  {
  	struct link_master *master = snd_kcontrol_chip(kcontrol);

  	struct link_follower *follower, *n;

  	/* free all follower links and retore the original follower kctls */
  	list_for_each_entry_safe(follower, n, &master->followers, list) {
  		struct snd_kcontrol *sctl = follower->kctl;

  		struct list_head olist = sctl->list;

  		memcpy(sctl, &follower->follower, sizeof(*sctl));
  		memcpy(sctl->vd, follower->follower.vd,

  		       sctl->count * sizeof(*sctl->vd));
  		sctl->list = olist; /* keep the current linked-list */

  		kfree(follower);

  	}

  	kfree(master);
  }

  /**
   * snd_ctl_make_virtual_master - Create a virtual master control
   * @name: name string of the control element to create
   * @tlv: optional TLV int array for dB information
   *

   * Creates a virtual master control with the given name string.

   *

   * After creating a vmaster element, you can add the follower controls
   * via snd_ctl_add_follower() or snd_ctl_add_follower_uncached().

   *
   * The optional argument @tlv can be used to specify the TLV information
   * for dB scale of the master control.  It should be a single element

   * with #SNDRV_CTL_TLVT_DB_SCALE, #SNDRV_CTL_TLV_DB_MINMAX or
   * #SNDRV_CTL_TLVT_DB_MINMAX_MUTE type, and should be the max 0dB.

   *
   * Return: The created control element, or %NULL for errors (ENOMEM).

   */
  struct snd_kcontrol *snd_ctl_make_virtual_master(char *name,
  						 const unsigned int *tlv)
  {
  	struct link_master *master;
  	struct snd_kcontrol *kctl;
  	struct snd_kcontrol_new knew;
  
  	memset(&knew, 0, sizeof(knew));
  	knew.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
  	knew.name = name;
  	knew.info = master_info;
  
  	master = kzalloc(sizeof(*master), GFP_KERNEL);
  	if (!master)
  		return NULL;

  	INIT_LIST_HEAD(&master->followers);

  
  	kctl = snd_ctl_new1(&knew, master);
  	if (!kctl) {
  		kfree(master);
  		return NULL;
  	}
  	/* override some callbacks */
  	kctl->info = master_info;
  	kctl->get = master_get;
  	kctl->put = master_put;
  	kctl->private_free = master_free;
  
  	/* additional (constant) TLV read */

  	if (tlv) {
  		unsigned int type = tlv[SNDRV_CTL_TLVO_TYPE];
  		if (type == SNDRV_CTL_TLVT_DB_SCALE ||
  		    type == SNDRV_CTL_TLVT_DB_MINMAX ||
  		    type == SNDRV_CTL_TLVT_DB_MINMAX_MUTE) {
  			kctl->vd[0].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
  			memcpy(master->tlv, tlv, sizeof(master->tlv));
  			kctl->tlv.p = master->tlv;
  		}

  	}

  	return kctl;
  }

  EXPORT_SYMBOL(snd_ctl_make_virtual_master);

  
  /**
   * snd_ctl_add_vmaster_hook - Add a hook to a vmaster control
   * @kcontrol: vmaster kctl element
   * @hook: the hook function

   * @private_data: the private_data pointer to be saved

   *
   * Adds the given hook to the vmaster control element so that it's called
   * at each time when the value is changed.

   *
   * Return: Zero.

   */
  int snd_ctl_add_vmaster_hook(struct snd_kcontrol *kcontrol,
  			     void (*hook)(void *private_data, int),
  			     void *private_data)
  {
  	struct link_master *master = snd_kcontrol_chip(kcontrol);
  	master->hook = hook;
  	master->hook_private_data = private_data;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(snd_ctl_add_vmaster_hook);
  
  /**

   * snd_ctl_sync_vmaster - Sync the vmaster followers and hook

   * @kcontrol: vmaster kctl element

   * @hook_only: sync only the hook

   *

   * Forcibly call the put callback of each follower and call the hook function

   * to synchronize with the current value of the given vmaster element.
   * NOP when NULL is passed to @kcontrol.

   */

  void snd_ctl_sync_vmaster(struct snd_kcontrol *kcontrol, bool hook_only)

  {
  	struct link_master *master;

  	bool first_init = false;

  	if (!kcontrol)
  		return;
  	master = snd_kcontrol_chip(kcontrol);

  	if (!hook_only) {
  		int err = master_init(master);
  		if (err < 0)
  			return;
  		first_init = err;

  		err = sync_followers(master, master->val, master->val);

  		if (err < 0)
  			return;
  	}
  
  	if (master->hook && !first_init)

  		master->hook(master->hook_private_data, master->val);
  }

  EXPORT_SYMBOL_GPL(snd_ctl_sync_vmaster);

  
  /**

   * snd_ctl_apply_vmaster_followers - Apply function to each vmaster follower

   * @kctl: vmaster kctl element
   * @func: function to apply
   * @arg: optional function argument
   *

   * Apply the function @func to each follower kctl of the given vmaster kctl.

   * Returns 0 if successful, or a negative error code.
   */

  int snd_ctl_apply_vmaster_followers(struct snd_kcontrol *kctl,
  				    int (*func)(struct snd_kcontrol *vfollower,
  						struct snd_kcontrol *follower,
  						void *arg),
  				    void *arg)

  {
  	struct link_master *master;

  	struct link_follower *follower;

  	int err;
  
  	master = snd_kcontrol_chip(kctl);
  	err = master_init(master);
  	if (err < 0)
  		return err;

  	list_for_each_entry(follower, &master->followers, list) {
  		err = func(follower->kctl, &follower->follower, arg);

  		if (err < 0)
  			return err;
  	}
  
  	return 0;
  }

  EXPORT_SYMBOL_GPL(snd_ctl_apply_vmaster_followers);