ASoC: dmaengine_pcm: add processing support

Allow dmaengine client to optionally register a processing callback.
This callback is intended to apply processing
on samples in buffer copied from/to user space, before/after DMA transfer.

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

2 files changed, 63 insertions, 2 deletions

diff --git a/include/sound/dmaengine_pcm.h b/include/sound/dmaengine_pcm.h
index 8a5a8404966e..47ef486852ed 100644
--- a/include/sound/dmaengine_pcm.h
+++ b/include/sound/dmaengine_pcm.h
@@ -140,6 +140,9 @@ struct snd_dmaengine_pcm_config {
         struct dma_chan *(*compat_request_channel)(
                         struct snd_soc_pcm_runtime *rtd,
                         struct snd_pcm_substream *substream);
+        int (*process)(struct snd_pcm_substream *substream,
+                       int channel, unsigned long hwoff,
+                       void *buf, unsigned long bytes);
         dma_filter_fn compat_filter_fn;
         struct device *dma_dev;
         const char *chan_names[SNDRV_PCM_STREAM_LAST + 1];
diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c
index 785f25ede3e5..567fbdfd1ca9 100644
--- a/sound/soc/soc-generic-dmaengine-pcm.c
+++ b/sound/soc/soc-generic-dmaengine-pcm.c
@@ -341,6 +341,41 @@ static snd_pcm_uframes_t dmaengine_pcm_pointer(
                 return snd_dmaengine_pcm_pointer(substream);
 }
 
+static int dmaengine_copy_user(struct snd_pcm_substream *substream,
+                               int channel, unsigned long hwoff,
+                               void *buf, unsigned long bytes)
+{
+        struct snd_soc_pcm_runtime *rtd = substream->private_data;
+        struct snd_soc_component *component =
+                snd_soc_rtdcom_lookup(rtd, SND_DMAENGINE_PCM_DRV_NAME);
+        struct snd_pcm_runtime *runtime = substream->runtime;
+        struct dmaengine_pcm *pcm = soc_component_to_pcm(component);
+        int (*process)(struct snd_pcm_substream *substream,
+                       int channel, unsigned long hwoff,
+                       void *buf, unsigned long bytes) = pcm->config->process;
+        bool is_playback = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
+        void *dma_ptr = runtime->dma_area + hwoff +
+                        channel * (runtime->dma_bytes / runtime->channels);
+        int ret;
+
+        if (is_playback)
+                if (copy_from_user(dma_ptr, (void __user *)buf, bytes))
+                        return -EFAULT;
+
+        if (process) {
+                ret = process(substream, channel, hwoff,
+                              (void __user *)buf, bytes);
+                if (ret < 0)
+                        return ret;
+        }
+
+        if (!is_playback)
+                if (copy_to_user((void __user *)buf, dma_ptr, bytes))
+                        return -EFAULT;
+
+        return 0;
+}
+
 static const struct snd_pcm_ops dmaengine_pcm_ops = {
         .open           = dmaengine_pcm_open,
         .close          = snd_dmaengine_pcm_close,
@@ -351,6 +386,17 @@ static const struct snd_pcm_ops dmaengine_pcm_ops = {
         .pointer        = dmaengine_pcm_pointer,
 };
 
+static const struct snd_pcm_ops dmaengine_pcm_process_ops = {
+        .open           = dmaengine_pcm_open,
+        .close          = snd_dmaengine_pcm_close,
+        .ioctl          = snd_pcm_lib_ioctl,
+        .hw_params      = dmaengine_pcm_hw_params,
+        .hw_free        = snd_pcm_lib_free_pages,
+        .trigger        = snd_dmaengine_pcm_trigger,
+        .pointer        = dmaengine_pcm_pointer,
+        .copy_user      = dmaengine_copy_user,
+};
+
 static const struct snd_soc_component_driver dmaengine_pcm_component = {
         .name           = SND_DMAENGINE_PCM_DRV_NAME,
         .probe_order    = SND_SOC_COMP_ORDER_LATE,
@@ -358,6 +404,13 @@ static const struct snd_soc_component_driver dmaengine_pcm_component = {
         .pcm_new        = dmaengine_pcm_new,
 };
 
+static const struct snd_soc_component_driver dmaengine_pcm_component_process = {
+        .name           = SND_DMAENGINE_PCM_DRV_NAME,
+        .probe_order    = SND_SOC_COMP_ORDER_LATE,
+        .ops            = &dmaengine_pcm_process_ops,
+        .pcm_new        = dmaengine_pcm_new,
+};
+
 static const char * const dmaengine_pcm_dma_channel_names[] = {
         [SNDRV_PCM_STREAM_PLAYBACK] = "tx",
         [SNDRV_PCM_STREAM_CAPTURE] = "rx",
@@ -453,8 +506,13 @@ int snd_dmaengine_pcm_register(struct device *dev,
         if (ret)
                 goto err_free_pcm;
 
-        ret = snd_soc_add_component(dev, &pcm->component,
-                                    &dmaengine_pcm_component, NULL, 0);
+        if (config && config->process)
+                ret = snd_soc_add_component(dev, &pcm->component,
+                                            &dmaengine_pcm_component_process,
+                                            NULL, 0);
+        else
+                ret = snd_soc_add_component(dev, &pcm->component,
+                                            &dmaengine_pcm_component, NULL, 0);
         if (ret)
                 goto err_free_dma;