[ALSA] Control API - TLV implementation for additional information like dB scale

This patch implements a TLV mechanism to transfer an additional information
like dB scale to the user space. The types might be extended in future.
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

include/sound/asound.h

@@ -688,7 +688,7 @@ struct snd_timer_tread {
  *                                                                          *
  ****************************************************************************/
 
-#define SNDRV_CTL_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 3)
+#define SNDRV_CTL_VERSION		SNDRV_PROTOCOL_VERSION(2, 0, 4)
 
 struct snd_ctl_card_info {
 	int card;			/* card number */
@@ -818,6 +818,12 @@ struct snd_ctl_elem_value {
         unsigned char reserved[128-sizeof(struct timespec)];
 };
 
+struct snd_ctl_tlv {
+        unsigned int numid;	/* control element numeric identification */
+        unsigned int length;	/* in bytes aligned to 4 */
+        unsigned int tlv[0];	/* first TLV */
+};
+
 enum {
 	SNDRV_CTL_IOCTL_PVERSION = _IOR('U', 0x00, int),
 	SNDRV_CTL_IOCTL_CARD_INFO = _IOR('U', 0x01, struct snd_ctl_card_info),
@@ -831,6 +837,7 @@ enum {
 	SNDRV_CTL_IOCTL_ELEM_ADD = _IOWR('U', 0x17, struct snd_ctl_elem_info),
 	SNDRV_CTL_IOCTL_ELEM_REPLACE = _IOWR('U', 0x18, struct snd_ctl_elem_info),
 	SNDRV_CTL_IOCTL_ELEM_REMOVE = _IOWR('U', 0x19, struct snd_ctl_elem_id),
+	SNDRV_CTL_IOCTL_TLV_READ = _IOWR('U', 0x1a, struct snd_ctl_tlv),
 	SNDRV_CTL_IOCTL_HWDEP_NEXT_DEVICE = _IOWR('U', 0x20, int),
 	SNDRV_CTL_IOCTL_HWDEP_INFO = _IOR('U', 0x21, struct snd_hwdep_info),
 	SNDRV_CTL_IOCTL_PCM_NEXT_DEVICE = _IOR('U', 0x30, int),

include/sound/control.h

@@ -42,6 +42,7 @@ struct snd_kcontrol_new {
 	snd_kcontrol_info_t *info;
 	snd_kcontrol_get_t *get;
 	snd_kcontrol_put_t *put;
+	unsigned int *tlv;
 	unsigned long private_value;
 };
 
@@ -58,6 +59,7 @@ struct snd_kcontrol {
 	snd_kcontrol_info_t *info;
 	snd_kcontrol_get_t *get;
 	snd_kcontrol_put_t *put;
+	unsigned int *tlv;
 	unsigned long private_value;
 	void *private_data;
 	void (*private_free)(struct snd_kcontrol *kcontrol);

include/sound/tlv.h

+#ifndef __SOUND_TLV_H
+#define __SOUND_TLV_H
+
+/*
+ *  Advanced Linux Sound Architecture - ALSA - Driver
+ *  Copyright (c) 2006 by Jaroslav Kysela <perex@suse.cz>
+ *
+ *
+ *   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; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ */
+
+/*
+ * TLV structure is right behind the struct snd_ctl_tlv:
+ *   unsigned int type  	- see SNDRV_CTL_TLVT_*
+ *   unsigned int length
+ *   .... data aligned to sizeof(unsigned int), use
+ *        block_length = (length + (sizeof(unsigned int) - 1)) &
+ *                       ~(sizeof(unsigned int) - 1)) ....
+ */
+
+#define SNDRV_CTL_TLVT_CONTAINER 0	/* one level down - group of TLVs */
+#define SNDRV_CTL_TLVT_DB_SCALE	1       /* dB scale */
+
+#define DECLARE_TLV_DB_SCALE(name, min, step, mute) \
+unsigned int name[] = { \
+        SNDRV_CTL_TLVT_DB_SCALE, 2 * sizeof(unsigned int), \
+        (min), ((step) & 0xffff) | ((mute) ? 0x10000 : 0) \
+}
+
+#endif /* __SOUND_TLV_H */

sound/core/control.c

@@ -241,6 +241,7 @@ struct snd_kcontrol *snd_ctl_new1(const struct snd_kcontrol_new *ncontrol,
 	kctl.info = ncontrol->info;
 	kctl.get = ncontrol->get;
 	kctl.put = ncontrol->put;
+	kctl.tlv = ncontrol->tlv;
 	kctl.private_value = ncontrol->private_value;
 	kctl.private_data = private_data;
 	return snd_ctl_new(&kctl, access);
@@ -1067,6 +1068,40 @@ static int snd_ctl_subscribe_events(struct snd_ctl_file *file, int __user *ptr)
 	return 0;
 }
 
+static int snd_ctl_tlv_read(struct snd_card *card,
+                            struct snd_ctl_tlv __user *_tlv)
+{
+	struct snd_ctl_tlv tlv;
+	struct snd_kcontrol *kctl;
+	unsigned int len;
+	int err = 0;
+
+	if (copy_from_user(&tlv, _tlv, sizeof(tlv)))
+		return -EFAULT;
+        if (tlv.length < sizeof(unsigned int) * 3)
+                return -EINVAL;
+        down_read(&card->controls_rwsem);
+        kctl = snd_ctl_find_numid(card, tlv.numid);
+        if (kctl == NULL) {
+                err = -ENOENT;
+                goto __kctl_end;
+        }
+        if (kctl->tlv == NULL) {
+                err = -ENXIO;
+                goto __kctl_end;
+        }
+        len = kctl->tlv[1] + 2 * sizeof(unsigned int);
+        if (tlv.length < len) {
+                err = -ENOMEM;
+                goto __kctl_end;
+        }
+        if (copy_to_user(_tlv->tlv, kctl->tlv, len))
+        	err = -EFAULT;
+      __kctl_end:
+        up_read(&card->controls_rwsem);
+        return err;
+}
+
 static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 {
 	struct snd_ctl_file *ctl;
@@ -1086,11 +1121,11 @@ static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg
 	case SNDRV_CTL_IOCTL_CARD_INFO:
 		return snd_ctl_card_info(card, ctl, cmd, argp);
 	case SNDRV_CTL_IOCTL_ELEM_LIST:
-		return snd_ctl_elem_list(ctl->card, argp);
+		return snd_ctl_elem_list(card, argp);
 	case SNDRV_CTL_IOCTL_ELEM_INFO:
 		return snd_ctl_elem_info_user(ctl, argp);
 	case SNDRV_CTL_IOCTL_ELEM_READ:
-		return snd_ctl_elem_read_user(ctl->card, argp);
+		return snd_ctl_elem_read_user(card, argp);
 	case SNDRV_CTL_IOCTL_ELEM_WRITE:
 		return snd_ctl_elem_write_user(ctl, argp);
 	case SNDRV_CTL_IOCTL_ELEM_LOCK:
@@ -1105,6 +1140,8 @@ static long snd_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg
 		return snd_ctl_elem_remove(ctl, argp);
 	case SNDRV_CTL_IOCTL_SUBSCRIBE_EVENTS:
 		return snd_ctl_subscribe_events(ctl, ip);
+        case SNDRV_CTL_IOCTL_TLV_READ:
+                return snd_ctl_tlv_read(card, argp);
 	case SNDRV_CTL_IOCTL_POWER:
 		return -ENOPROTOOPT;
 	case SNDRV_CTL_IOCTL_POWER_STATE:

sound/pci/ca0106/ca0106_mixer.c

@@ -70,9 +70,12 @@
 #include <sound/pcm.h>
 #include <sound/ac97_codec.h>
 #include <sound/info.h>
+#include <sound/tlv.h>
 
 #include "ca0106.h"
 
+static DECLARE_TLV_DB_SCALE(snd_ca0106_db_scale, -5150, 75, 1);
+
 static int snd_ca0106_shared_spdif_info(struct snd_kcontrol *kcontrol,
 					struct snd_ctl_elem_info *uinfo)
 {
@@ -472,6 +475,7 @@ static int snd_ca0106_i2c_volume_put(struct snd_kcontrol *kcontrol,
 	.info =	 snd_ca0106_volume_info,			\
 	.get =   snd_ca0106_volume_get,				\
 	.put =   snd_ca0106_volume_put,				\
+	.tlv =	 snd_ca0106_db_scale,				\
 	.private_value = ((chid) << 8) | (reg)			\
 }