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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>
15#include <sound/tlv.h>
16
17/*
18 * a subset of information returned via ctl info callback
19 */
20struct link_ctl_info {
21 snd_ctl_elem_type_t 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 */
34struct link_master {
35 struct list_head slaves;
36 struct link_ctl_info info;
37 int val; /* the master value */
38 unsigned int tlv[4];
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
48struct link_slave {
49 struct list_head list;
50 struct link_master *master;
51 struct link_ctl_info info;
52 int vals[2]; /* current values */
53 unsigned int flags;
54 struct snd_kcontrol slave; /* the copy of original control entry */
55};
56
57static 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
73/* get the slave ctl info and save the initial values */
74static int slave_init(struct link_slave *slave)
75{
76 struct snd_ctl_elem_info *uinfo;
77 int err;
78
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 }
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
108 return slave_update(slave);
109}
110
111/* initialize master volume */
112static 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
132static 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
145static 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 */
179static 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
186static 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
193static 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
213static 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
222static 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 function 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 */
244int _snd_ctl_add_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave,
245 unsigned int flags)
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;
257 srec->flags = flags;
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}
271EXPORT_SYMBOL(_snd_ctl_add_slave);
272
273/*
274 * ctl callbacks for master controls
275 */
276static 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
292static 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
303static 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
332static 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
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, #SNDRV_CTL_TLV_DB_MINMAX or
357 * #SNDRV_CTL_TLVT_DB_MINMAX_MUTE type, and should be the max 0dB.
358 */
359struct snd_kcontrol *snd_ctl_make_virtual_master(char *name,
360 const unsigned int *tlv)
361{
362 struct link_master *master;
363 struct snd_kcontrol *kctl;
364 struct snd_kcontrol_new knew;
365
366 memset(&knew, 0, sizeof(knew));
367 knew.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
368 knew.name = name;
369 knew.info = master_info;
370
371 master = kzalloc(sizeof(*master), GFP_KERNEL);
372 if (!master)
373 return NULL;
374 INIT_LIST_HEAD(&master->slaves);
375
376 kctl = snd_ctl_new1(&knew, master);
377 if (!kctl) {
378 kfree(master);
379 return NULL;
380 }
381 /* override some callbacks */
382 kctl->info = master_info;
383 kctl->get = master_get;
384 kctl->put = master_put;
385 kctl->private_free = master_free;
386
387 /* additional (constant) TLV read */
388 if (tlv &&
389 (tlv[0] == SNDRV_CTL_TLVT_DB_SCALE ||
390 tlv[0] == SNDRV_CTL_TLVT_DB_MINMAX ||
391 tlv[0] == SNDRV_CTL_TLVT_DB_MINMAX_MUTE)) {
392 kctl->vd[0].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
393 memcpy(master->tlv, tlv, sizeof(master->tlv));
394 kctl->tlv.p = master->tlv;
395 }
396
397 return kctl;
398}
399EXPORT_SYMBOL(snd_ctl_make_virtual_master);
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>
15#include <sound/tlv.h>
16
17/*
18 * a subset of information returned via ctl info callback
19 */
20struct link_ctl_info {
21 snd_ctl_elem_type_t 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 */
34struct link_master {
35 struct list_head slaves;
36 struct link_ctl_info info;
37 int val; /* the master value */
38 unsigned int tlv[4];
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
48struct link_slave {
49 struct list_head list;
50 struct link_master *master;
51 struct link_ctl_info info;
52 int vals[2]; /* current values */
53 unsigned int flags;
54 struct snd_kcontrol slave; /* the copy of original control entry */
55};
56
57static 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
73/* get the slave ctl info and save the initial values */
74static int slave_init(struct link_slave *slave)
75{
76 struct snd_ctl_elem_info *uinfo;
77 int err;
78
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 }
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
108 return slave_update(slave);
109}
110
111/* initialize master volume */
112static 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
132static 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
145static 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 */
179static 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
186static 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
193static 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
213static 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
222static 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 function 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 */
244int _snd_ctl_add_slave(struct snd_kcontrol *master, struct snd_kcontrol *slave,
245 unsigned int flags)
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;
257 srec->flags = flags;
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}
271EXPORT_SYMBOL(_snd_ctl_add_slave);
272
273/*
274 * ctl callbacks for master controls
275 */
276static 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
292static 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
303static 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
332static 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
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, #SNDRV_CTL_TLV_DB_MINMAX or
357 * #SNDRV_CTL_TLVT_DB_MINMAX_MUTE type, and should be the max 0dB.
358 */
359struct snd_kcontrol *snd_ctl_make_virtual_master(char *name,
360 const unsigned int *tlv)
361{
362 struct link_master *master;
363 struct snd_kcontrol *kctl;
364 struct snd_kcontrol_new knew;
365
366 memset(&knew, 0, sizeof(knew));
367 knew.iface = SNDRV_CTL_ELEM_IFACE_MIXER;
368 knew.name = name;
369 knew.info = master_info;
370
371 master = kzalloc(sizeof(*master), GFP_KERNEL);
372 if (!master)
373 return NULL;
374 INIT_LIST_HEAD(&master->slaves);
375
376 kctl = snd_ctl_new1(&knew, master);
377 if (!kctl) {
378 kfree(master);
379 return NULL;
380 }
381 /* override some callbacks */
382 kctl->info = master_info;
383 kctl->get = master_get;
384 kctl->put = master_put;
385 kctl->private_free = master_free;
386
387 /* additional (constant) TLV read */
388 if (tlv &&
389 (tlv[0] == SNDRV_CTL_TLVT_DB_SCALE ||
390 tlv[0] == SNDRV_CTL_TLVT_DB_MINMAX ||
391 tlv[0] == SNDRV_CTL_TLVT_DB_MINMAX_MUTE)) {
392 kctl->vd[0].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
393 memcpy(master->tlv, tlv, sizeof(master->tlv));
394 kctl->tlv.p = master->tlv;
395 }
396
397 return kctl;
398}
399EXPORT_SYMBOL(snd_ctl_make_virtual_master);