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

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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>
This commit is contained in:
Jaroslav Kysela
2006-06-01 18:34:01 +02:00
parent 3eeab61aa3
commit 42750b04c5
5 changed files with 96 additions and 3 deletions
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41
sound/core/control.c
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@@ -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: