ASoC: dapm: Add demux support

A demux is conceptually similar to a mux. Where a mux has multiple input
and one output and selects one of the inputs to be connected to the output,
the demux has one input and multiple outputs and selects one of the outputs
to which the input gets connected.

This similarity makes it straight forward to support them in DAPM using the
existing mux support, we only need to swap sinks and sources when initially
setting up the paths.

The only slightly tricky part is that there can only be one control per
path. Since mixers/muxes are at the sink of a path and a demux is at the
source and both types want a control it is not possible to directly connect
a demux output to a mixer/mux input. The patch adds some sanity checks to
make sure that this does not happen.

Drivers who want to model hardware which directly connects a demux output
to a mixer/mux input can do this by inserting a dummy widget between the
two. E.g.:

	{ "Dummy", "Demux Control", "Demux" },
	{ "Mixer", "Mixer Control", "Dummy" },

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/sound/soc-dapm.h b/include/sound/soc-dapm.h
index 70216d20e897..96c5e0ec81d1 100644
--- a/include/sound/soc-dapm.h
+++ b/include/sound/soc-dapm.h
@@ -107,6 +107,10 @@ struct device;
 {       .id = snd_soc_dapm_mux, .name = wname, \
         SND_SOC_DAPM_INIT_REG_VAL(wreg, wshift, winvert), \
         .kcontrol_news = wcontrols, .num_kcontrols = 1}
+#define SND_SOC_DAPM_DEMUX(wname, wreg, wshift, winvert, wcontrols) \
+{       .id = snd_soc_dapm_demux, .name = wname, \
+        SND_SOC_DAPM_INIT_REG_VAL(wreg, wshift, winvert), \
+        .kcontrol_news = wcontrols, .num_kcontrols = 1}
 
 /* Simplified versions of above macros, assuming wncontrols = ARRAY_SIZE(wcontrols) */
 #define SOC_PGA_ARRAY(wname, wreg, wshift, winvert,\
@@ -452,6 +456,7 @@ enum snd_soc_dapm_type {
         snd_soc_dapm_input = 0,         /* input pin */
         snd_soc_dapm_output,            /* output pin */
         snd_soc_dapm_mux,                       /* selects 1 analog signal from many inputs */
+        snd_soc_dapm_demux,                     /* connects the input to one of multiple outputs */
         snd_soc_dapm_mixer,                     /* mixes several analog signals together */
         snd_soc_dapm_mixer_named_ctl,           /* mixer with named controls */
         snd_soc_dapm_pga,                       /* programmable gain/attenuation (volume) */