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

/*
 * a subset of information returned via ctl info callback
 */
struct link_ctl_info {
        int 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 */
        struct snd_kcontrol slave; /* the copy of original control entry */
};

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

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

        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\n");
                kfree(uinfo);
                return -EINVAL;
        }
        slave->info.min_val = uinfo->value.integer.min;
        slave->info.max_val = uinfo->value.integer.max;
        kfree(uinfo);

        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;
}

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

        /* 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;

        list_for_each_entry(slave, &master->slaves, list)
                slave->master = NULL;
        kfree(master);
}


/*
 * Create a virtual master control with the given name
 */
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) {
                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);