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control_external: Add ability to specify TLV data.

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Allow external control plugins to provide TLV data.  This allows
user-space pcms to specify dB ranges for controls.

This follows the same model as the ALSA drivers for accessing the
data.  The code is based on that implementation.  The control can
provide static data or a callback.  The data is accessed or modified
in the new snd_ctl_ext_elem_tlv callback.

Rev bump the protocol version to enable checking if an external
control supports TLV.

Signed-off-by: Dylan Reid <dgreid@chromium.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Dylan Reid 2012-04-15 16:59:55 -07:00 • committed by Takashi Iwai
parent ed0e48583f
commit a6c50d64d9
2 changed files with 62 additions and 1 deletions
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46
src/control/control_ext.c
View file

@ -324,6 +324,51 @@ static int snd_ctl_ext_elem_unlock(snd_ctl_t *handle ATTRIBUTE_UNUSED,
return -ENXIO;
}
static int snd_ctl_ext_elem_tlv(snd_ctl_t *handle, int op_flag,
unsigned int numid,
unsigned int *tlv, unsigned int tlv_size)
{
snd_ctl_ext_t *ext = handle->private_data;
snd_ctl_ext_key_t key;
int type, ret;
unsigned int access, count, len;
snd_ctl_elem_id_t id;
/* we don't support TLV on protocol ver 1.0.0 or earlier */
if (ext->version <= SNDRV_PROTOCOL_VERSION(1, 0, 0))
return -ENXIO;
snd_ctl_elem_id_clear(&id);
if (numid > 0) {
ext->callback->elem_list(ext, numid - 1, &id);
id.numid = numid;
} else
id.numid = 0;
key = ext->callback->find_elem(ext, &id);
if (key == SND_CTL_EXT_KEY_NOT_FOUND)
return -ENOENT;
ret = ext->callback->get_attribute(ext, key, &type, &access, &count);
if (ret < 0)
return ret;
if ((op_flag == 0 && (access & SND_CTL_EXT_ACCESS_TLV_READ) == 0) ||
(op_flag > 0 && (access & SND_CTL_EXT_ACCESS_TLV_WRITE) == 0) ||
(op_flag < 0 && (access & SND_CTL_EXT_ACCESS_TLV_COMMAND) == 0))
return -ENXIO;
if (access & SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK) {
return ext->tlv.c(ext, key, op_flag, numid, tlv, tlv_size);
} else {
if (op_flag)
return -ENXIO;
len = ext->tlv.p[1] + 2 * sizeof(unsigned int);
if (tlv_size < len)
return -ENOMEM;
memcpy(tlv, ext->tlv.p, len);
return 0;
}
}
static int snd_ctl_ext_next_device(snd_ctl_t *handle ATTRIBUTE_UNUSED,
int *device ATTRIBUTE_UNUSED)
{
@ -429,6 +474,7 @@ static const snd_ctl_ops_t snd_ctl_ext_ops = {
.element_write = snd_ctl_ext_elem_write,
.element_lock = snd_ctl_ext_elem_lock,
.element_unlock = snd_ctl_ext_elem_unlock,
.element_tlv = snd_ctl_ext_elem_tlv,
.hwdep_next_device = snd_ctl_ext_next_device,
.hwdep_info = snd_ctl_ext_hwdep_info,
.pcm_next_device = snd_ctl_ext_next_device,