[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>

3 files changed, 53 insertions, 1 deletions

diff --git a/include/sound/asound.h b/include/sound/asound.h
index 41885f48ad91..76a20406bd18 100644
--- a/include/sound/asound.h
+++ b/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),
diff --git a/include/sound/control.h b/include/sound/control.h
index 2489b1eb0110..a93a58d0e688 100644
--- a/include/sound/control.h
+++ b/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);
diff --git a/include/sound/tlv.h b/include/sound/tlv.h
new file mode 100644
index 000000000000..b826e1df1da6
--- /dev/null
+++ b/include/sound/tlv.h
@@ -0,0 +1,43 @@
+#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 */