/*
   * Virtual master and slave controls
   *
   *  Copyright (c) 2008 by Takashi Iwai <tiwai@suse.de>
   *
   *  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, version 2.
   *
   */
  
  #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 slave 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 slaves.
   */
  struct link_master {
  	struct list_head slaves;
  	struct link_ctl_info info;
  	int val;		/* the master value */

  	unsigned int tlv[4];

  };
  
  /*
   * link slave - this contains a slave control element
   *
   * It fakes the control callbacsk with additional attenuation by the
   * master control.  A slave may have either one or two channels.
   */
  
  struct link_slave {
  	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 slave; /* the copy of original control entry */
  };

  static int slave_update(struct link_slave *slave)
  {
  	struct snd_ctl_elem_value *uctl;
  	int err, ch;
  
  	uctl = kmalloc(sizeof(*uctl), GFP_KERNEL);
  	if (!uctl)
  		return -ENOMEM;
  	uctl->id = slave->slave.id;
  	err = slave->slave.get(&slave->slave, uctl);
  	for (ch = 0; ch < slave->info.count; ch++)
  		slave->vals[ch] = uctl->value.integer.value[ch];
  	kfree(uctl);
  	return 0;
  }

  /* get the slave ctl info and save the initial values */
  static int slave_init(struct link_slave *slave)
  {
  	struct snd_ctl_elem_info *uinfo;

  	int err;

  	if (slave->info.count) {
  		/* already initialized */
  		if (slave->flags & SND_CTL_SLAVE_NEED_UPDATE)
  			return slave_update(slave);
  		return 0;
  	}

  
  	uinfo = kmalloc(sizeof(*uinfo), GFP_KERNEL);
  	if (!uinfo)
  		return -ENOMEM;
  	uinfo->id = slave->slave.id;
  	err = slave->slave.info(&slave->slave, uinfo);
  	if (err < 0) {
  		kfree(uinfo);
  		return err;
  	}
  	slave->info.type = uinfo->type;
  	slave->info.count = uinfo->count;
  	if (slave->info.count > 2  ||
  	    (slave->info.type != SNDRV_CTL_ELEM_TYPE_INTEGER &&
  	     slave->info.type != SNDRV_CTL_ELEM_TYPE_BOOLEAN)) {
  		snd_printk(KERN_ERR "invalid slave element
  ");
  		kfree(uinfo);
  		return -EINVAL;
  	}
  	slave->info.min_val = uinfo->value.integer.min;
  	slave->info.max_val = uinfo->value.integer.max;
  	kfree(uinfo);

  	return slave_update(slave);

  }
  
  /* initialize master volume */
  static int master_init(struct link_master *master)
  {
  	struct link_slave *slave;
  
  	if (master->info.count)
  		return 0; /* already initialized */
  
  	list_for_each_entry(slave, &master->slaves, list) {
  		int err = slave_init(slave);
  		if (err < 0)
  			return err;
  		master->info = slave->info;
  		master->info.count = 1; /* always mono */
  		/* set full volume as default (= no attenuation) */
  		master->val = master->info.max_val;
  		return 0;
  	}
  	return -ENOENT;
  }
  
  static int slave_get_val(struct link_slave *slave,
  			 struct snd_ctl_elem_value *ucontrol)
  {
  	int err, ch;
  
  	err = slave_init(slave);
  	if (err < 0)
  		return err;
  	for (ch = 0; ch < slave->info.count; ch++)
  		ucontrol->value.integer.value[ch] = slave->vals[ch];
  	return 0;
  }
  
  static int slave_put_val(struct link_slave *slave,
  			 struct snd_ctl_elem_value *ucontrol)
  {
  	int err, ch, vol;
  
  	err = master_init(slave->master);
  	if (err < 0)
  		return err;
  
  	switch (slave->info.type) {
  	case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
  		for (ch = 0; ch < slave->info.count; ch++)
  			ucontrol->value.integer.value[ch] &=
  				!!slave->master->val;
  		break;
  	case SNDRV_CTL_ELEM_TYPE_INTEGER:
  		for (ch = 0; ch < slave->info.count; ch++) {
  			/* max master volume is supposed to be 0 dB */
  			vol = ucontrol->value.integer.value[ch];
  			vol += slave->master->val - slave->master->info.max_val;
  			if (vol < slave->info.min_val)
  				vol = slave->info.min_val;
  			else if (vol > slave->info.max_val)
  				vol = slave->info.max_val;
  			ucontrol->value.integer.value[ch] = vol;
  		}
  		break;
  	}
  	return slave->slave.put(&slave->slave, ucontrol);
  }
  
  /*
   * ctl callbacks for slaves
   */
  static int slave_info(struct snd_kcontrol *kcontrol,
  		      struct snd_ctl_elem_info *uinfo)
  {
  	struct link_slave *slave = snd_kcontrol_chip(kcontrol);
  	return slave->slave.info(&slave->slave, uinfo);
  }
  
  static int slave_get(struct snd_kcontrol *kcontrol,
  		     struct snd_ctl_elem_value *ucontrol)
  {
  	struct link_slave *slave = snd_kcontrol_chip(kcontrol);
  	return slave_get_val(slave, ucontrol);
  }
  
  static int slave_put(struct snd_kcontrol *kcontrol,
  		     struct snd_ctl_elem_value *ucontrol)
  {
  	struct link_slave *slave = snd_kcontrol_chip(kcontrol);
  	int err, ch, changed = 0;
  
  	err = slave_init(slave);
  	if (err < 0)
  		return err;
  	for (ch = 0; ch < slave->info.count; ch++) {
  		if (slave->vals[ch] != ucontrol->value.integer.value[ch]) {
  			changed = 1;
  			slave->vals[ch] = ucontrol->value.integer.value[ch];
  		}
  	}
  	if (!changed)
  		return 0;
  	return slave_put_val(slave, ucontrol);
  }
  
  static int slave_tlv_cmd(struct snd_kcontrol *kcontrol,
  			 int op_flag, unsigned int size,
  			 unsigned int __user *tlv)
  {
  	struct link_slave *slave = snd_kcontrol_chip(kcontrol);
  	/* FIXME: this assumes that the max volume is 0 dB */
  	return slave->slave.tlv.c(&slave->slave, op_flag, size, tlv);
  }
  
  static void slave_free(struct snd_kcontrol *kcontrol)
  {
  	struct link_slave *slave = snd_kcontrol_chip(kcontrol);
  	if (slave->slave.private_free)
  		slave->slave.private_free(&slave->slave);
  	if (slave->master)
  		list_del(&slave->list);
  	kfree(slave);
  }
  
  /*
   * Add a slave control to the group with the given master control
   *
   * All slaves 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_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave,
  		       unsigned int flags)

  {
  	struct link_master *master_link = snd_kcontrol_chip(master);
  	struct link_slave *srec;
  
  	srec = kzalloc(sizeof(*srec) +
  		       slave->count * sizeof(*slave->vd), GFP_KERNEL);
  	if (!srec)
  		return -ENOMEM;

  	srec->kctl = slave;

  	srec->slave = *slave;
  	memcpy(srec->slave.vd, slave->vd, slave->count * sizeof(*slave->vd));
  	srec->master = master_link;

  	srec->flags = flags;

  
  	/* override callbacks */
  	slave->info = slave_info;
  	slave->get = slave_get;
  	slave->put = slave_put;
  	if (slave->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK)
  		slave->tlv.c = slave_tlv_cmd;
  	slave->private_data = srec;
  	slave->private_free = slave_free;
  
  	list_add_tail(&srec->list, &master_link->slaves);
  	return 0;
  }

  EXPORT_SYMBOL(_snd_ctl_add_slave);

  /*
   * 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 master_put(struct snd_kcontrol *kcontrol,
  		      struct snd_ctl_elem_value *ucontrol)
  {
  	struct link_master *master = snd_kcontrol_chip(kcontrol);
  	struct link_slave *slave;
  	struct snd_ctl_elem_value *uval;
  	int err, old_val;
  
  	err = master_init(master);
  	if (err < 0)
  		return err;
  	old_val = master->val;
  	if (ucontrol->value.integer.value[0] == old_val)
  		return 0;
  
  	uval = kmalloc(sizeof(*uval), GFP_KERNEL);
  	if (!uval)
  		return -ENOMEM;
  	list_for_each_entry(slave, &master->slaves, list) {
  		master->val = old_val;
  		uval->id = slave->slave.id;
  		slave_get_val(slave, uval);
  		master->val = ucontrol->value.integer.value[0];
  		slave_put_val(slave, uval);
  	}
  	kfree(uval);
  	return 1;
  }
  
  static void master_free(struct snd_kcontrol *kcontrol)
  {
  	struct link_master *master = snd_kcontrol_chip(kcontrol);

  	struct link_slave *slave, *n;
  
  	/* free all slave links and retore the original slave kctls */
  	list_for_each_entry_safe(slave, n, &master->slaves, list) {
  		struct snd_kcontrol *sctl = slave->kctl;
  		struct list_head olist = sctl->list;
  		memcpy(sctl, &slave->slave, sizeof(*sctl));
  		memcpy(sctl->vd, slave->slave.vd,
  		       sctl->count * sizeof(*sctl->vd));
  		sctl->list = olist; /* keep the current linked-list */
  		kfree(slave);
  	}

  	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 matster control with the given name string.
   * Returns the created control element, or NULL for errors (ENOMEM).
   *
   * After creating a vmaster element, you can add the slave controls
   * via snd_ctl_add_slave() or snd_ctl_add_slave_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.

   */
  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->slaves);
  
  	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 &&
  	    (tlv[0] == SNDRV_CTL_TLVT_DB_SCALE ||
  	     tlv[0] == SNDRV_CTL_TLVT_DB_MINMAX ||
  	     tlv[0] == 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);