ALSA: Add SoC on-chip internal ram support for DMA buffer allocation

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

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

Signed-off-by: Nicolin Chen <b42378@freescale.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

3 files changed, 59 insertions, 0 deletions

diff --git a/include/sound/memalloc.h b/include/sound/memalloc.h
index cf15b8213df7..510aec437f72 100644
--- a/include/sound/memalloc.h
+++ b/include/sound/memalloc.h
@@ -52,6 +52,7 @@ struct snd_dma_device {
 #else
 #define SNDRV_DMA_TYPE_DEV_SG   SNDRV_DMA_TYPE_DEV /* no SG-buf support */
 #endif
+#define SNDRV_DMA_TYPE_DEV_IRAM         4       /* generic device iram-buffer */
 
 /*
  * info for buffer allocation
diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c
index bdf826f4fe0c..18c1d4759ccb 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 +158,46 @@ 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);
 }
+
+/**
+ * snd_malloc_dev_iram - allocate memory from on-chip internal ram
+ * @dmab: buffer allocation record to store the allocated data
+ * @size: number of bytes to allocate from the iram
+ *
+ * This function requires iram phandle provided via of_node
+ */
+void snd_malloc_dev_iram(struct snd_dma_buffer *dmab, size_t size)
+{
+        struct device *dev = dmab->dev.dev;
+        struct gen_pool *pool = NULL;
+
+        if (dev->of_node)
+                pool = of_get_named_gen_pool(dev->of_node, "iram", 0);
+
+        if (!pool)
+                return;
+
+        /* Assign the pool into private_data field */
+        dmab->private_data = pool;
+
+        dmab->area = (void *)gen_pool_alloc(pool, size);
+        if (!dmab->area)
+                return;
+
+        dmab->addr = gen_pool_virt_to_phys(pool, (unsigned long)dmab->area);
+}
+
+/**
+ * snd_free_dev_iram - free allocated specific memory from on-chip internal ram
+ * @dmab: buffer allocation record to store the allocated data
+ */
+void snd_free_dev_iram(struct snd_dma_buffer *dmab)
+{
+        struct gen_pool *pool = dmab->private_data;
+
+        if (pool && dmab->area)
+                gen_pool_free(pool, (unsigned long)dmab->area, dmab->bytes);
+}
 #endif /* CONFIG_HAS_DMA */
 
 /*
@@ -197,6 +238,14 @@ 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:
+                snd_malloc_dev_iram(dmab, size);
+                if (dmab->area)
+                        break;
+                /* 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 +318,9 @@ 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:
+                snd_free_dev_iram(dmab);
+                break;
         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 a68d4c6d702c..513f0954d92e 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -3199,6 +3199,12 @@ 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) {
+                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)