ASoC: core - add hostless DAI support

Allow DAI's to be hostless so that no PCM data is sent between DAI
and CPU. This allows for power savings as there is no DMA or CPU
interaction required.

TODO: we shouldn't need to allocate a PAGE for a dummy DMA buffer.

Signed-off-by: Liam Girdwood <lrg@ti.com>

1 files changed, 39 insertions, 1 deletions

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 5895bae24956..875847621231 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -24,6 +24,7 @@
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 #include <linux/debugfs.h>
+#include <linux/dma-mapping.h>
 #include <sound/core.h>
 #include <sound/pcm.h>
 #include <sound/pcm_params.h>
@@ -31,6 +32,24 @@
 #include <sound/soc-dsp.h>
 #include <sound/initval.h>
 
+/* ASoC no host IO hardware.
+ * TODO: fine tune these values for all host less transfers.
+ */
+static const struct snd_pcm_hardware no_host_hardware = {
+	.info			= SNDRV_PCM_INFO_MMAP |
+				  SNDRV_PCM_INFO_MMAP_VALID |
+				  SNDRV_PCM_INFO_INTERLEAVED |
+				  SNDRV_PCM_INFO_PAUSE |
+				  SNDRV_PCM_INFO_RESUME,
+	.formats		= SNDRV_PCM_FMTBIT_S16_LE |
+				  SNDRV_PCM_FMTBIT_S32_LE,
+	.period_bytes_min	= PAGE_SIZE >> 2,
+	.period_bytes_max	= PAGE_SIZE >> 1,
+	.periods_min		= 2,
+	.periods_max		= 4,
+	.buffer_bytes_max	= PAGE_SIZE,
+};
+
 /* count the number of FE clients in a particular state */
 int soc_dsp_fe_state_count(struct snd_soc_pcm_runtime *be, int stream,
 				enum snd_soc_dsp_state state)
@@ -99,6 +118,9 @@ static int soc_pcm_open(struct snd_pcm_substream *substream)
 
 	mutex_lock_nested(&rtd->pcm_mutex, rtd->pcm_subclass);
 
+	if (rtd->dai_link->no_host_mode == SND_SOC_DAI_LINK_NO_HOST)
+		snd_soc_set_runtime_hwparams(substream, &no_host_hardware);
+
 	/* startup the audio subsystem */
 	if (cpu_dai->driver->ops->startup) {
 		ret = cpu_dai->driver->ops->startup(substream, cpu_dai);
@@ -491,6 +513,20 @@ static int soc_pcm_hw_params(struct snd_pcm_substream *substream,
 	cpu_dai->rate = params_rate(params);
 	codec_dai->rate = params_rate(params);
 
+	/* malloc a page for hostless IO.
+	 * FIXME: rework with alsa-lib changes so that this malloc is not required.
+	 */
+	if (rtd->dai_link->no_host_mode == SND_SOC_DAI_LINK_NO_HOST) {
+		substream->dma_buffer.dev.type = SNDRV_DMA_TYPE_DEV;
+		substream->dma_buffer.dev.dev = &rtd->dev;
+		substream->dma_buffer.dev.dev->coherent_dma_mask = DMA_BIT_MASK(32);
+		substream->dma_buffer.private_data = NULL;
+
+		ret = snd_pcm_lib_malloc_pages(substream, PAGE_SIZE);
+		if (ret < 0)
+			goto platform_err;
+	}
+
 out:
 	mutex_unlock(&rtd->pcm_mutex);
 	return ret;
@@ -543,6 +579,9 @@ static int soc_pcm_hw_free(struct snd_pcm_substream *substream)
 	if (cpu_dai->driver->ops->hw_free)
 		cpu_dai->driver->ops->hw_free(substream, cpu_dai);
 
+	if (rtd->dai_link->no_host_mode == SND_SOC_DAI_LINK_NO_HOST)
+		snd_pcm_lib_free_pages(substream);
+
 	mutex_unlock(&rtd->pcm_mutex);
 	return 0;
 }
@@ -2159,7 +2198,6 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
 				&no_host_hardware);
 	}
 
-
 	/* ASoC PCM operations */
 	if (rtd->dai_link->dynamic) {
 		rtd->ops.open		= soc_dsp_fe_dai_open;