ASoC: generic-dmaengine-pcm: Add support for half-duplex

Some platforms which are half-duplex share the same DMA channel between the
playback and capture stream. Add support for this to the generic dmaengine PCM
driver.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 30 insertions, 13 deletions

diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c
index ae0c37e66ae0..5fd5ed4c0a96 100644
--- a/sound/soc/soc-generic-dmaengine-pcm.c
+++ b/sound/soc/soc-generic-dmaengine-pcm.c
@@ -29,7 +29,7 @@ struct dmaengine_pcm {
         struct dma_chan *chan[SNDRV_PCM_STREAM_CAPTURE + 1];
         const struct snd_dmaengine_pcm_config *config;
         struct snd_soc_platform platform;
-        bool compat;
+        unsigned int flags;
 };
 
 static struct dmaengine_pcm *soc_platform_to_pcm(struct snd_soc_platform *p)
@@ -128,6 +128,9 @@ static struct dma_chan *dmaengine_pcm_compat_request_channel(
 {
         struct dmaengine_pcm *pcm = soc_platform_to_pcm(rtd->platform);
 
+        if ((pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX) && pcm->chan[0])
+                return pcm->chan[0];
+
         if (pcm->config->compat_request_channel)
                 return pcm->config->compat_request_channel(rtd, substream);
 
@@ -148,7 +151,7 @@ static int dmaengine_pcm_new(struct snd_soc_pcm_runtime *rtd)
                 if (!substream)
                         continue;
 
-                if (!pcm->chan[i] && pcm->compat) {
+                if (!pcm->chan[i] && (pcm->flags & SND_DMAENGINE_PCM_FLAG_COMPAT)) {
                         pcm->chan[i] = dmaengine_pcm_compat_request_channel(rtd,
                                 substream);
                 }
@@ -215,6 +218,25 @@ static const char * const dmaengine_pcm_dma_channel_names[] = {
         [SNDRV_PCM_STREAM_CAPTURE] = "rx",
 };
 
+static void dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm,
+        struct device_node *of_node)
+{
+        unsigned int i;
+
+        if ((pcm->flags & SND_DMAENGINE_PCM_FLAG_NO_DT) || !of_node)
+                return;
+
+        if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX) {
+                pcm->chan[0] = of_dma_request_slave_channel(of_node, "tx_rx");
+                pcm->chan[1] = pcm->chan[0];
+        } else {
+                for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
+                        pcm->chan[i] = of_dma_request_slave_channel(of_node,
+                                        dmaengine_pcm_dma_channel_names[i]);
+                }
+        }
+}
+
 /**
  * snd_dmaengine_pcm_register - Register a dmaengine based PCM device
  * @dev: The parent device for the PCM device
@@ -225,23 +247,15 @@ int snd_dmaengine_pcm_register(struct device *dev,
         const struct snd_dmaengine_pcm_config *config, unsigned int flags)
 {
         struct dmaengine_pcm *pcm;
-        unsigned int i;
 
         pcm = kzalloc(sizeof(*pcm), GFP_KERNEL);
         if (!pcm)
                 return -ENOMEM;
 
         pcm->config = config;
+        pcm->flags = flags;
 
-        if (flags & SND_DMAENGINE_PCM_FLAG_COMPAT)
-                pcm->compat = true;
-
-        if (!(flags & SND_DMAENGINE_PCM_FLAG_NO_DT) && dev->of_node) {
-                for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
-                        pcm->chan[i] = of_dma_request_slave_channel(dev->of_node,
-                                        dmaengine_pcm_dma_channel_names[i]);
-                }
-        }
+        dmaengine_pcm_request_chan_of(pcm, dev->of_node);
 
         if (flags & SND_DMAENGINE_PCM_FLAG_NO_RESIDUE)
                 return snd_soc_add_platform(dev, &pcm->platform,
@@ -272,8 +286,11 @@ void snd_dmaengine_pcm_unregister(struct device *dev)
         pcm = soc_platform_to_pcm(platform);
 
         for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
-                if (pcm->chan[i])
+                if (pcm->chan[i]) {
                         dma_release_channel(pcm->chan[i]);
+                        if (pcm->flags & SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX)
+                                break;
+                }
         }
 
         snd_soc_remove_platform(platform);