ASoC: dapm: add a dapm sink widget

DAPM models various widgets but lacks a sink widget.
DSPs can have modules which take audio data, process it and are
capable of generating events thus acting as a sink of data.

To make the dapm graph complete for such paths we need a dapm
sink widget for these modules, so add a SND_SOC_DAPM_SINK to
declare such a widget.  This widget will be treated as
SND_SOC_DAPM_EP_SINK endpoint in the dapm graph
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc-dapm.h

@@ -49,6 +49,9 @@ struct device;
 #define SND_SOC_DAPM_SIGGEN(wname) \
 {	.id = snd_soc_dapm_siggen, .name = wname, .kcontrol_news = NULL, \
 	.num_kcontrols = 0, .reg = SND_SOC_NOPM }
+#define SND_SOC_DAPM_SINK(wname) \
+{	.id = snd_soc_dapm_sink, .name = wname, .kcontrol_news = NULL, \
+	.num_kcontrols = 0, .reg = SND_SOC_NOPM }
 #define SND_SOC_DAPM_INPUT(wname) \
 {	.id = snd_soc_dapm_input, .name = wname, .kcontrol_news = NULL, \
 	.num_kcontrols = 0, .reg = SND_SOC_NOPM }
@@ -484,6 +487,7 @@ enum snd_soc_dapm_type {
 	snd_soc_dapm_aif_in,		/* audio interface input */
 	snd_soc_dapm_aif_out,		/* audio interface output */
 	snd_soc_dapm_siggen,		/* signal generator */
+	snd_soc_dapm_sink,
 	snd_soc_dapm_dai_in,		/* link to DAI structure */
 	snd_soc_dapm_dai_out,
 	snd_soc_dapm_dai_link,		/* link between two DAI structures */

sound/soc/soc-dapm.c

@@ -3351,6 +3351,11 @@ snd_soc_dapm_new_control_unlocked(struct snd_soc_dapm_context *dapm,
 		w->is_ep = SND_SOC_DAPM_EP_SOURCE;
 		w->power_check = dapm_always_on_check_power;
 		break;
+	case snd_soc_dapm_sink:
+		w->is_ep = SND_SOC_DAPM_EP_SINK;
+		w->power_check = dapm_always_on_check_power;
+		break;
+
 	case snd_soc_dapm_mux:
 	case snd_soc_dapm_demux:
 	case snd_soc_dapm_switch: