[alsa-devel] [PATCH v3] ALSA: Add SoC on-chip internal memory support for DMA buffer allocation

[Nicolin Chen]

Now it's quite common that an SoC contains its on-chip internal memory.
By using this memory space for DMA buffer during audio playback/record,
we can shutdown the voltage for external memory to save power.

Thus add new DEV type with iram malloc()/free() and accordingly modify
current default mmap() for the iram circumstance.

Signed-off-by: Nicolin Chen <b42378 at freescale.com>
---
Changelog
v2->v3:
 * Moved iram specific mmap procedure out of ifdef ARCH_HAS_DMA_MMAP_COHERENT
v1->v2:
 * Added of_node check
 * Dropped noops and unused physical addr in snd_free_dev_iram()

---
 include/sound/memalloc.h |  5 ++++
 sound/core/memalloc.c    | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
 sound/core/pcm_native.c  |  7 +++++
 3 files changed, 84 insertions(+)

diff --git a/include/sound/memalloc.h b/include/sound/memalloc.h
index cf15b82..b53443e 100644
--- a/include/sound/memalloc.h
+++ b/include/sound/memalloc.h
@@ -52,6 +52,11 @@ struct snd_dma_device {
 #else
 #define SNDRV_DMA_TYPE_DEV_SG	SNDRV_DMA_TYPE_DEV /* no SG-buf support */
 #endif
+#ifdef CONFIG_OF
+#define SNDRV_DMA_TYPE_DEV_IRAM		4	/* generic device iram-buffer */
+#else
+#define SNDRV_DMA_TYPE_DEV_IRAM		SNDRV_DMA_TYPE_DEV
+#endif
 
 /*
  * info for buffer allocation
diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c
index bdf826f..2957938 100644
--- a/sound/core/memalloc.c
+++ b/sound/core/memalloc.c
@@ -30,6 +30,7 @@
 #include <linux/seq_file.h>
 #include <asm/uaccess.h>
 #include <linux/dma-mapping.h>
+#include <linux/genalloc.h>
 #include <linux/moduleparam.h>
 #include <linux/mutex.h>
 #include <sound/memalloc.h>
@@ -157,6 +158,61 @@ static void snd_free_dev_pages(struct device *dev, size_t size, void *ptr,
 	dec_snd_pages(pg);
 	dma_free_coherent(dev, PAGE_SIZE << pg, ptr, dma);
 }
+
+#ifdef CONFIG_OF
+/**
+ * snd_malloc_dev_iram - allocate memory from on-chip internal memory
+ * @dev: DMA device pointer
+ * @size: number of bytes to allocate from the iram
+ * @dma: dma-view physical address
+ *
+ * Return cpu-view address or NULL indicating allocating failure
+ *
+ * This function requires iram phandle provided via of_node
+ */
+void *snd_malloc_dev_iram(struct device *dev, size_t size, dma_addr_t *dma)
+{
+	struct gen_pool *pool;
+	unsigned long vaddr;
+
+	if (!dev->of_node)
+		return NULL;
+
+	pool = of_get_named_gen_pool(dev->of_node, "iram", 0);
+	if (!pool)
+		return NULL;
+
+	vaddr = gen_pool_alloc(pool, size);
+	if (!vaddr)
+		return NULL;
+
+	*dma = gen_pool_virt_to_phys(pool, vaddr);
+
+	return (void *)vaddr;
+}
+
+/**
+ * snd_free_dev_iram - free allocated specific memory from on-chip internal memory
+ * @dev: DMA device pointer
+ * @size: size in bytes of memory to free
+ * @ptr: cpu-view address returned from snd_malloc_dev_iram
+ *
+ * This function requires iram phandle provided via of_node
+ */
+void snd_free_dev_iram(struct device *dev, size_t size, void *ptr)
+{
+	struct gen_pool *pool;
+
+	if (!dev->of_node)
+		return;
+
+	pool = of_get_named_gen_pool(dev->of_node, "iram", 0);
+	if (!pool)
+		return;
+
+	gen_pool_free(pool, (unsigned long)ptr, size);
+}
+#endif /* CONFIG_OF */
 #endif /* CONFIG_HAS_DMA */
 
 /*
@@ -197,6 +253,17 @@ int snd_dma_alloc_pages(int type, struct device *device, size_t size,
 		dmab->addr = 0;
 		break;
 #ifdef CONFIG_HAS_DMA
+	case SNDRV_DMA_TYPE_DEV_IRAM:
+#ifdef CONFIG_OF
+		dmab->area = snd_malloc_dev_iram(device, size, &dmab->addr);
+		if (dmab->area)
+			break;
+#endif
+		/*
+		 * Internal memory might have limited size and no enough space,
+		 * so if we fail to malloc, try to fetch memory traditionally.
+		 */
+		dmab->dev.type = SNDRV_DMA_TYPE_DEV;
 	case SNDRV_DMA_TYPE_DEV:
 		dmab->area = snd_malloc_dev_pages(device, size, &dmab->addr);
 		break;
@@ -269,6 +336,11 @@ void snd_dma_free_pages(struct snd_dma_buffer *dmab)
 		snd_free_pages(dmab->area, dmab->bytes);
 		break;
 #ifdef CONFIG_HAS_DMA
+	case SNDRV_DMA_TYPE_DEV_IRAM:
+#ifdef CONFIG_OF
+		snd_free_dev_iram(dmab->dev.dev, dmab->bytes, dmab->area);
+			break;
+#endif
 	case SNDRV_DMA_TYPE_DEV:
 		snd_free_dev_pages(dmab->dev.dev, dmab->bytes, dmab->area, dmab->addr);
 		break;
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index a68d4c6..74de2a3 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -3199,6 +3199,13 @@ int snd_pcm_lib_default_mmap(struct snd_pcm_substream *substream,
 			     struct vm_area_struct *area)
 {
 	area->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+	if (substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV_IRAM &&
+			SNDRV_DMA_TYPE_DEV_IRAM != SNDRV_DMA_TYPE_DEV) {
+		area->vm_page_prot = pgprot_writecombine(area->vm_page_prot);
+		return remap_pfn_range(area, area->vm_start,
+				substream->dma_buffer.addr >> PAGE_SHIFT,
+				area->vm_end - area->vm_start, area->vm_page_prot);
+	}
 #ifdef ARCH_HAS_DMA_MMAP_COHERENT
 	if (!substream->ops->page &&
 	    substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV)
-- 
1.8.4