Re: [alsa-devel] [PATCH v7] ALSA: Add SoC on-chip internal ram support for DMA buffer allocation

At Wed, 23 Oct 2013 11:47:43 +0800, Nicolin Chen wrote:

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

Thanks, now applied with ack by Lars.

Takashi

---

Changelog v6->v7:

• Assigned pool to private_data field and accordingly refined helper functions.

v5->v6:

• Dropped remaining OF dependency bacause no need to add them: of_node doesn't care about OF; of_get_named_gen_pool() returns NULL if !OF.

v4->v5:

• Minimized the OF dependency.

v3->v4:

• Appropriately placed '#ifdef CONFIG_OF'
• Tested by adding '#undef CONFIG_OF' to modified files, and passed compiling.

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 | 1 + sound/core/memalloc.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++ sound/core/pcm_native.c | 6 ++++++ 3 files changed, 59 insertions(+)

diff --git a/include/sound/memalloc.h b/include/sound/memalloc.h index cf15b82..510aec4 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 bdf826f..18c1d47 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 a68d4c6..513f095 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) -- 1.8.4