ASoC: soc-pcm: Allow to specify unidirectional dai_link

Add 'playback_only' and 'capture_only' fields that can be used for specifying
that a dai_link has a unidirectional capability.

The motivation for this is for the cases of systems, such as Freescale MX28,
that has two unidirectional DAIs.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

2 files changed, 14 insertions, 0 deletions

diff --git a/include/sound/soc.h b/include/sound/soc.h
index c0ac3bc7b7f4..65414e82c762 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -936,6 +936,10 @@ struct snd_soc_dai_link {
         /* machine stream operations */
         const struct snd_soc_ops *ops;
         const struct snd_soc_compr_ops *compr_ops;
+
+        /* For unidirectional dai links */
+        bool playback_only;
+        bool capture_only;
 };
 
 struct snd_soc_codec_conf {
diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index b6c640332a17..9abaa52efb2e 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -2027,6 +2027,16 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
                         capture = 1;
         }
 
+        if (rtd->dai_link->playback_only) {
+                playback = 1;
+                capture = 0;
+        }
+
+        if (rtd->dai_link->capture_only) {
+                playback = 0;
+                capture = 1;
+        }
+
         /* create the PCM */
         if (rtd->dai_link->no_pcm) {
                 snprintf(new_name, sizeof(new_name), "(%s)",