[GitHub/mt8127/android_kernel_alcatel_ttab.git] / sound / core / vmaster.c

/*
 * 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 */
	unsigned int flags;
	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\n");
		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 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,
		       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->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;

	list_for_each_entry(slave, &master->slaves, list)
		slave->master = NULL;
	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 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) {
		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);
Commit	Line	Data
3b0a5f22 TI	1	/*
	2	* Virtual master and slave controls
	3	*
	4	* Copyright (c) 2008 by Takashi Iwai <tiwai@suse.de>
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License as
	8	* published by the Free Software Foundation, version 2.
	9	*
	10	*/
	11
	12	#include <linux/slab.h>
	13	#include <sound/core.h>
	14	#include <sound/control.h>
1c82ed1b	15	#include <sound/tlv.h>
3b0a5f22 TI	16
	17	/*
	18	* a subset of information returned via ctl info callback
	19	*/
	20	struct link_ctl_info {
	21	int type; /* value type */
	22	int count; /* item count */
	23	int min_val, max_val; /* min, max values */
	24	};
	25
	26	/*
	27	* link master - this contains a list of slave controls that are
	28	* identical types, i.e. info returns the same value type and value
	29	* ranges, but may have different number of counts.
	30	*
	31	* The master control is so far only mono volume/switch for simplicity.
	32	* The same value will be applied to all slaves.
	33	*/
	34	struct link_master {
	35	struct list_head slaves;
	36	struct link_ctl_info info;
	37	int val; /* the master value */
1c82ed1b	38	unsigned int tlv[4];
3b0a5f22 TI	39	};
	40
	41	/*
	42	* link slave - this contains a slave control element
	43	*
	44	* It fakes the control callbacsk with additional attenuation by the
	45	* master control. A slave may have either one or two channels.
	46	*/
	47
	48	struct link_slave {
	49	struct list_head list;
	50	struct link_master *master;
	51	struct link_ctl_info info;
	52	int vals[2]; /* current values */
f5b1db63	53	unsigned int flags;
3b0a5f22 TI	54	struct snd_kcontrol slave; /* the copy of original control entry */
	55	};
	56
f5b1db63 TI	57	static int slave_update(struct link_slave *slave)
	58	{
	59	struct snd_ctl_elem_value *uctl;
	60	int err, ch;
	61
	62	uctl = kmalloc(sizeof(*uctl), GFP_KERNEL);
	63	if (!uctl)
	64	return -ENOMEM;
	65	uctl->id = slave->slave.id;
	66	err = slave->slave.get(&slave->slave, uctl);
	67	for (ch = 0; ch < slave->info.count; ch++)
	68	slave->vals[ch] = uctl->value.integer.value[ch];
	69	kfree(uctl);
	70	return 0;
	71	}
	72
3b0a5f22 TI	73	/* get the slave ctl info and save the initial values */
	74	static int slave_init(struct link_slave *slave)
	75	{
	76	struct snd_ctl_elem_info *uinfo;
f5b1db63	77	int err;
3b0a5f22	78
f5b1db63 TI	79	if (slave->info.count) {
	80	/* already initialized */
	81	if (slave->flags & SND_CTL_SLAVE_NEED_UPDATE)
	82	return slave_update(slave);
	83	return 0;
	84	}
3b0a5f22 TI	85
	86	uinfo = kmalloc(sizeof(*uinfo), GFP_KERNEL);
	87	if (!uinfo)
	88	return -ENOMEM;
	89	uinfo->id = slave->slave.id;
	90	err = slave->slave.info(&slave->slave, uinfo);
	91	if (err < 0) {
	92	kfree(uinfo);
	93	return err;
	94	}
	95	slave->info.type = uinfo->type;
	96	slave->info.count = uinfo->count;
	97	if (slave->info.count > 2 \|\|
	98	(slave->info.type != SNDRV_CTL_ELEM_TYPE_INTEGER &&
	99	slave->info.type != SNDRV_CTL_ELEM_TYPE_BOOLEAN)) {
	100	snd_printk(KERN_ERR "invalid slave element\n");
	101	kfree(uinfo);
	102	return -EINVAL;
	103	}
	104	slave->info.min_val = uinfo->value.integer.min;
	105	slave->info.max_val = uinfo->value.integer.max;
	106	kfree(uinfo);
	107
f5b1db63	108	return slave_update(slave);
3b0a5f22 TI	109	}
	110
	111	/* initialize master volume */
	112	static int master_init(struct link_master *master)
	113	{
	114	struct link_slave *slave;
	115
	116	if (master->info.count)
	117	return 0; /* already initialized */
	118
	119	list_for_each_entry(slave, &master->slaves, list) {
	120	int err = slave_init(slave);
	121	if (err < 0)
	122	return err;
	123	master->info = slave->info;
	124	master->info.count = 1; /* always mono */
	125	/* set full volume as default (= no attenuation) */
	126	master->val = master->info.max_val;
	127	return 0;
	128	}
	129	return -ENOENT;
	130	}
	131
	132	static int slave_get_val(struct link_slave *slave,
	133	struct snd_ctl_elem_value *ucontrol)
	134	{
	135	int err, ch;
	136
	137	err = slave_init(slave);
	138	if (err < 0)
	139	return err;
	140	for (ch = 0; ch < slave->info.count; ch++)
	141	ucontrol->value.integer.value[ch] = slave->vals[ch];
	142	return 0;
	143	}
	144
	145	static int slave_put_val(struct link_slave *slave,
	146	struct snd_ctl_elem_value *ucontrol)
	147	{
	148	int err, ch, vol;
	149
	150	err = master_init(slave->master);
	151	if (err < 0)
	152	return err;
	153
	154	switch (slave->info.type) {
	155	case SNDRV_CTL_ELEM_TYPE_BOOLEAN:
	156	for (ch = 0; ch < slave->info.count; ch++)
	157	ucontrol->value.integer.value[ch] &=
	158	!!slave->master->val;
	159	break;
	160	case SNDRV_CTL_ELEM_TYPE_INTEGER:
	161	for (ch = 0; ch < slave->info.count; ch++) {
	162	/* max master volume is supposed to be 0 dB */
	163	vol = ucontrol->value.integer.value[ch];
	164	vol += slave->master->val - slave->master->info.max_val;
	165	if (vol < slave->info.min_val)
	166	vol = slave->info.min_val;
	167	else if (vol > slave->info.max_val)
	168	vol = slave->info.max_val;
	169	ucontrol->value.integer.value[ch] = vol;
	170	}
	171	break;
	172	}
173	return slave->slave.put(&slave->slave, ucontrol);
174	}
175
176	/*
177	* ctl callbacks for slaves
178	*/
179	static int slave_info(struct snd_kcontrol *kcontrol,
180	struct snd_ctl_elem_info *uinfo)
181	{
182	struct link_slave *slave = snd_kcontrol_chip(kcontrol);
183	return slave->slave.info(&slave->slave, uinfo);
184	}
185
186	static int slave_get(struct snd_kcontrol *kcontrol,
187	struct snd_ctl_elem_value *ucontrol)
188	{
189	struct link_slave *slave = snd_kcontrol_chip(kcontrol);
190	return slave_get_val(slave, ucontrol);
191	}
192
193	static int slave_put(struct snd_kcontrol *kcontrol,
194	struct snd_ctl_elem_value *ucontrol)
195	{
196	struct link_slave *slave = snd_kcontrol_chip(kcontrol);
197	int err, ch, changed = 0;
198
199	err = slave_init(slave);
200	if (err < 0)
201	return err;
202	for (ch = 0; ch < slave->info.count; ch++) {
203	if (slave->vals[ch] != ucontrol->value.integer.value[ch]) {
204	changed = 1;
205	slave->vals[ch] = ucontrol->value.integer.value[ch];
206	}
207	}
208	if (!changed)
209	return 0;
210	return slave_put_val(slave, ucontrol);
211	}
212
213	static int slave_tlv_cmd(struct snd_kcontrol *kcontrol,
214	int op_flag, unsigned int size,
215	unsigned int __user *tlv)
216	{
217	struct link_slave *slave = snd_kcontrol_chip(kcontrol);
218	/* FIXME: this assumes that the max volume is 0 dB */
219	return slave->slave.tlv.c(&slave->slave, op_flag, size, tlv);
220	}
221
222	static void slave_free(struct snd_kcontrol *kcontrol)
223	{
224	struct link_slave *slave = snd_kcontrol_chip(kcontrol);
225	if (slave->slave.private_free)
226	slave->slave.private_free(&slave->slave);
227	if (slave->master)
228	list_del(&slave->list);
229	kfree(slave);
230	}
231
232	/*
233	* Add a slave control to the group with the given master control
234	*
235	* All slaves must be the same type (returning the same information
236	* via info callback). The fucntion doesn't check it, so it's your
237	* responsibility.
238	*
239	* Also, some additional limitations:
240	* - at most two channels
241	* - logarithmic volume control (dB level), no linear volume
242	* - master can only attenuate the volume, no gain
243	*/
f5b1db63 TI	244	int _snd_ctl_add_slave(struct snd_kcontrol master, struct snd_kcontrol slave,
f5b1db63 TI	245	unsigned int flags)
3b0a5f22 TI	246	{
	247	struct link_master *master_link = snd_kcontrol_chip(master);
	248	struct link_slave *srec;
	249
	250	srec = kzalloc(sizeof(*srec) +
	251	slave->count * sizeof(*slave->vd), GFP_KERNEL);
	252	if (!srec)
	253	return -ENOMEM;
	254	srec->slave = *slave;
	255	memcpy(srec->slave.vd, slave->vd, slave->count * sizeof(*slave->vd));
	256	srec->master = master_link;
f5b1db63	257	srec->flags = flags;
3b0a5f22 TI	258
	259	/* override callbacks */
	260	slave->info = slave_info;
	261	slave->get = slave_get;
	262	slave->put = slave_put;
	263	if (slave->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK)
	264	slave->tlv.c = slave_tlv_cmd;
	265	slave->private_data = srec;
	266	slave->private_free = slave_free;
	267
	268	list_add_tail(&srec->list, &master_link->slaves);
	269	return 0;
	270	}
f5b1db63	271	EXPORT_SYMBOL(_snd_ctl_add_slave);
e922b002	272
3b0a5f22 TI	273	/*
	274	* ctl callbacks for master controls
	275	*/
	276	static int master_info(struct snd_kcontrol *kcontrol,
	277	struct snd_ctl_elem_info *uinfo)
	278	{
	279	struct link_master *master = snd_kcontrol_chip(kcontrol);
	280	int ret;
	281
	282	ret = master_init(master);
	283	if (ret < 0)
	284	return ret;
	285	uinfo->type = master->info.type;
	286	uinfo->count = master->info.count;
	287	uinfo->value.integer.min = master->info.min_val;
	288	uinfo->value.integer.max = master->info.max_val;
	289	return 0;
	290	}
	291
	292	static int master_get(struct snd_kcontrol *kcontrol,
	293	struct snd_ctl_elem_value *ucontrol)
	294	{
	295	struct link_master *master = snd_kcontrol_chip(kcontrol);
	296	int err = master_init(master);
	297	if (err < 0)
	298	return err;
	299	ucontrol->value.integer.value[0] = master->val;
	300	return 0;
	301	}
	302
	303	static int master_put(struct snd_kcontrol *kcontrol,
	304	struct snd_ctl_elem_value *ucontrol)
	305	{
	306	struct link_master *master = snd_kcontrol_chip(kcontrol);
	307	struct link_slave *slave;
	308	struct snd_ctl_elem_value *uval;
	309	int err, old_val;
	310
	311	err = master_init(master);
	312	if (err < 0)
	313	return err;
	314	old_val = master->val;
	315	if (ucontrol->value.integer.value[0] == old_val)
	316	return 0;
	317
	318	uval = kmalloc(sizeof(*uval), GFP_KERNEL);
	319	if (!uval)
	320	return -ENOMEM;
	321	list_for_each_entry(slave, &master->slaves, list) {
	322	master->val = old_val;
	323	uval->id = slave->slave.id;
	324	slave_get_val(slave, uval);
	325	master->val = ucontrol->value.integer.value[0];
	326	slave_put_val(slave, uval);
	327	}
	328	kfree(uval);
	329	return 1;
	330	}
	331
	332	static void master_free(struct snd_kcontrol *kcontrol)
	333	{
	334	struct link_master *master = snd_kcontrol_chip(kcontrol);
	335	struct link_slave *slave;
	336
337	list_for_each_entry(slave, &master->slaves, list)
338	slave->master = NULL;
339	kfree(master);
340	}
341
342
79c7cdd5 TI	343	/**
	344	* snd_ctl_make_virtual_master - Create a virtual master control
	345	* @name: name string of the control element to create
	346	* @tlv: optional TLV int array for dB information
	347	*
	348	* Creates a virtual matster control with the given name string.
	349	* Returns the created control element, or NULL for errors (ENOMEM).
	350	*
	351	* After creating a vmaster element, you can add the slave controls
	352	* via snd_ctl_add_slave() or snd_ctl_add_slave_uncached().
	353	*
	354	* The optional argument @tlv can be used to specify the TLV information
	355	* for dB scale of the master control. It should be a single element
	356	* with #SNDRV_CTL_TLVT_DB_SCALE type, and should be the max 0dB.
3b0a5f22 TI	357	*/
	358	struct snd_kcontrol snd_ctl_make_virtual_master(char name,
	359	const unsigned int *tlv)
	360	{
	361	struct link_master *master;
	362	struct snd_kcontrol *kctl;
	363	struct snd_kcontrol_new knew;
	364
	365	memset(&knew, 0, sizeof(knew));
	366	knew.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
	367	knew.name = name;
	368	knew.info = master_info;
	369
	370	master = kzalloc(sizeof(*master), GFP_KERNEL);
	371	if (!master)
	372	return NULL;
	373	INIT_LIST_HEAD(&master->slaves);
	374
	375	kctl = snd_ctl_new1(&knew, master);
	376	if (!kctl) {
	377	kfree(master);
	378	return NULL;
	379	}
	380	/* override some callbacks */
	381	kctl->info = master_info;
	382	kctl->get = master_get;
	383	kctl->put = master_put;
	384	kctl->private_free = master_free;
	385
	386	/* additional (constant) TLV read */
1c82ed1b	387	if (tlv && tlv[0] == SNDRV_CTL_TLVT_DB_SCALE) {
3b0a5f22	388	kctl->vd[0].access \|= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
1c82ed1b TI	389	memcpy(master->tlv, tlv, sizeof(master->tlv));
1c82ed1b TI	390	kctl->tlv.p = master->tlv;
3b0a5f22	391	}
1c82ed1b	392
3b0a5f22 TI	393	return kctl;
3b0a5f22 TI	394	}
e922b002	395	EXPORT_SYMBOL(snd_ctl_make_virtual_master);