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authorPeter Ujfalusi <peter.ujfalusi@nokia.com>2010-05-07 14:05:49 +0300
committerMark Brown <broonie@opensource.wolfsonmicro.com>2010-05-07 16:41:33 +0100
commit637d3847ba0ca2c7780e6521cbe75568d19ff0db (patch)
tree6a9b76e2d0365cabba43f7a273feceb66710bf4c /sound
parent305787649826d6c84a6f9f71bc3318460610aba4 (diff)
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ASoC: core: Support for limiting the volume
Add support for the core to limit the maximum volume on an existing control. The function will modify the soc_mixer_control.max value of the given control. The new value must be lower than the original one (chip maximum) If there is a need for limiting a gain on a given control, than machine drivers can do the following in their snd_soc_dai_link.init function: snd_soc_limit_volume(codec, "TPA6140A2 Headphone Playback Volume", 21); This will modify the original 31 (chip maximum) to 21, so user space will not be able to set the gain higher than this. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@nokia.com> Acked-by: Liam Girdwood <lrg@slimlogic.co.uk> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Diffstat (limited to 'sound')
-rw-r--r--sound/soc/soc-core.c39
1 files changed, 39 insertions, 0 deletions
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index d59076e..4079223 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -2238,6 +2238,45 @@ int snd_soc_put_volsw_s8(struct snd_kcontrol *kcontrol,
EXPORT_SYMBOL_GPL(snd_soc_put_volsw_s8);
/**
+ * snd_soc_limit_volume - Set new limit to an existing volume control.
+ *
+ * @codec: where to look for the control
+ * @name: Name of the control
+ * @max: new maximum limit
+ *
+ * Return 0 for success, else error.
+ */
+int snd_soc_limit_volume(struct snd_soc_codec *codec,
+ const char *name, int max)
+{
+ struct snd_card *card = codec->card;
+ struct snd_kcontrol *kctl;
+ struct soc_mixer_control *mc;
+ int found = 0;
+ int ret = -EINVAL;
+
+ /* Sanity check for name and max */
+ if (unlikely(!name || max <= 0))
+ return -EINVAL;
+
+ list_for_each_entry(kctl, &card->controls, list) {
+ if (!strncmp(kctl->id.name, name, sizeof(kctl->id.name))) {
+ found = 1;
+ break;
+ }
+ }
+ if (found) {
+ mc = (struct soc_mixer_control *)kctl->private_value;
+ if (max <= mc->max) {
+ mc->max = max;
+ ret = 0;
+ }
+ }
+ return ret;
+}
+EXPORT_SYMBOL_GPL(snd_soc_limit_volume);
+
+/**
* snd_soc_dai_set_sysclk - configure DAI system or master clock.
* @dai: DAI
* @clk_id: DAI specific clock ID