ASoC: atmel-pdc: Use managed DMA buffer allocation

Instead of manually managing its DMA buffers using
dma_{alloc,free}_coherent() lets the sound core take care of this using
managed buffers.

On one hand this reduces the amount of boiler plate code, but the main
motivation for the change is to use the shared code where possible. This
makes it easier to argue about correctness and that the code does not
contain subtle bugs like data leakage or similar.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Reviewed-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Link: https://lore.kernel.org/r/20210106133650.13509-1-lars@metafoo.deSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/atmel/atmel-pcm-pdc.c

@@ -34,86 +34,21 @@
 #include "atmel-pcm.h"
 
 
-static int atmel_pcm_preallocate_dma_buffer(struct snd_pcm *pcm,
-	int stream)
-{
-	struct snd_pcm_substream *substream = pcm->streams[stream].substream;
-	struct snd_dma_buffer *buf = &substream->dma_buffer;
-	size_t size = ATMEL_SSC_DMABUF_SIZE;
-
-	buf->dev.type = SNDRV_DMA_TYPE_DEV;
-	buf->dev.dev = pcm->card->dev;
-	buf->private_data = NULL;
-	buf->area = dma_alloc_coherent(pcm->card->dev, size,
-			&buf->addr, GFP_KERNEL);
-	pr_debug("atmel-pcm: alloc dma buffer: area=%p, addr=%p, size=%zu\n",
-			(void *)buf->area, (void *)(long)buf->addr, size);
-
-	if (!buf->area)
-		return -ENOMEM;
-
-	buf->bytes = size;
-	return 0;
-}
-
-static int atmel_pcm_mmap(struct snd_soc_component *component,
-			  struct snd_pcm_substream *substream,
-			  struct vm_area_struct *vma)
-{
-	return remap_pfn_range(vma, vma->vm_start,
-		       substream->dma_buffer.addr >> PAGE_SHIFT,
-		       vma->vm_end - vma->vm_start, vma->vm_page_prot);
-}
-
 static int atmel_pcm_new(struct snd_soc_component *component,
 			 struct snd_soc_pcm_runtime *rtd)
 {
 	struct snd_card *card = rtd->card->snd_card;
-	struct snd_pcm *pcm = rtd->pcm;
 	int ret;
 
 	ret = dma_coerce_mask_and_coherent(card->dev, DMA_BIT_MASK(32));
 	if (ret)
 		return ret;
 
-	if (pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream) {
-		pr_debug("atmel-pcm: allocating PCM playback DMA buffer\n");
-		ret = atmel_pcm_preallocate_dma_buffer(pcm,
-			SNDRV_PCM_STREAM_PLAYBACK);
-		if (ret)
-			goto out;
-	}
+	snd_pcm_set_managed_buffer_all(rtd->pcm, SNDRV_DMA_TYPE_DEV,
+				       card->dev, ATMEL_SSC_DMABUF_SIZE,
+				       ATMEL_SSC_DMABUF_SIZE);
 
-	if (pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream) {
-		pr_debug("atmel-pcm: allocating PCM capture DMA buffer\n");
-		ret = atmel_pcm_preallocate_dma_buffer(pcm,
-			SNDRV_PCM_STREAM_CAPTURE);
-		if (ret)
-			goto out;
-	}
- out:
-	return ret;
-}
-
-static void atmel_pcm_free(struct snd_soc_component *component,
-			   struct snd_pcm *pcm)
-{
-	struct snd_pcm_substream *substream;
-	struct snd_dma_buffer *buf;
-	int stream;
-
-	for (stream = 0; stream < 2; stream++) {
-		substream = pcm->streams[stream].substream;
-		if (!substream)
-			continue;
-
-		buf = &substream->dma_buffer;
-		if (!buf->area)
-			continue;
-		dma_free_coherent(pcm->card->dev, buf->bytes,
-				  buf->area, buf->addr);
-		buf->area = NULL;
-	}
+	return 0;
 }
 
 /*--------------------------------------------------------------------------*\
@@ -210,9 +145,6 @@ static int atmel_pcm_hw_params(struct snd_soc_component *component,
 	/* this may get called several times by oss emulation
 	 * with different params */
 
-	snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);
-	runtime->dma_bytes = params_buffer_bytes(params);
-
 	prtd->params = snd_soc_dai_get_dma_data(asoc_rtd_to_cpu(rtd, 0), substream);
 	prtd->params->dma_intr_handler = atmel_pcm_dma_irq;
 
@@ -384,9 +316,7 @@ static const struct snd_soc_component_driver atmel_soc_platform = {
 	.prepare	= atmel_pcm_prepare,
 	.trigger	= atmel_pcm_trigger,
 	.pointer	= atmel_pcm_pointer,
-	.mmap		= atmel_pcm_mmap,
 	.pcm_construct	= atmel_pcm_new,
-	.pcm_destruct	= atmel_pcm_free,
 };
 
 int atmel_pcm_pdc_platform_register(struct device *dev)