ALSA: memalloc: Add non-cached buffer type

In some cases (mainly for x86), we need the DMA coherent buffer with
non-cached pages.  Although this has been done in each driver side
like HD-audio and intel8x0, it can be done cleaner in the core memory
allocator.

This patch adds the new types, SNDRV_DMA_TYPE_DEV_UC and
SNDRV_DMA_TYPE_DEV_UC_SG, for allocating such non-cached buffer
pages.  On non-x86 architectures, they work as same as the standard
SNDRV_DMA_TYPE_DEV and *_SG.

One additional change by this move is that we can assure to pass the
non-cached pgprot to the vmapped buffer, too.  It eventually fixes the
case like non-snoop mode without mmap access on HD-audio.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/memalloc.h

@@ -47,10 +47,13 @@ struct snd_dma_device {
 #define SNDRV_DMA_TYPE_UNKNOWN		0	/* not defined */
 #define SNDRV_DMA_TYPE_CONTINUOUS	1	/* continuous no-DMA memory */
 #define SNDRV_DMA_TYPE_DEV		2	/* generic device continuous */
+#define SNDRV_DMA_TYPE_DEV_UC		5	/* continuous non-cahced */
 #ifdef CONFIG_SND_DMA_SGBUF
 #define SNDRV_DMA_TYPE_DEV_SG		3	/* generic device SG-buffer */
+#define SNDRV_DMA_TYPE_DEV_UC_SG	6	/* SG non-cached */
 #else
 #define SNDRV_DMA_TYPE_DEV_SG	SNDRV_DMA_TYPE_DEV /* no SG-buf support */
+#define SNDRV_DMA_TYPE_DEV_UC_SG	SNDRV_DMA_TYPE_DEV_UC
 #endif
 #ifdef CONFIG_GENERIC_ALLOCATOR
 #define SNDRV_DMA_TYPE_DEV_IRAM		4	/* generic device iram-buffer */

sound/core/memalloc.c

@@ -25,6 +25,9 @@
 #include <linux/mm.h>
 #include <linux/dma-mapping.h>
 #include <linux/genalloc.h>
+#ifdef CONFIG_X86
+#include <asm/set_memory.h>
+#endif
 #include <sound/memalloc.h>
 
 /*
@@ -92,11 +95,21 @@ static void snd_malloc_dev_pages(struct snd_dma_buffer *dmab, size_t size)
 		| __GFP_NOWARN; /* no stack trace print - this call is non-critical */
 	dmab->area = dma_alloc_coherent(dmab->dev.dev, size, &dmab->addr,
 					gfp_flags);
+#ifdef CONFIG_X86
+	if (dmab->area && dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC)
+		set_memory_wc((unsigned long)dmab->area,
+			      PAGE_ALIGN(size) >> PAGE_SHIFT);
+#endif
 }
 
 /* free the coherent DMA pages */
 static void snd_free_dev_pages(struct snd_dma_buffer *dmab)
 {
+#ifdef CONFIG_X86
+	if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC)
+		set_memory_wb((unsigned long)dmab->area,
+			      PAGE_ALIGN(dmab->bytes) >> PAGE_SHIFT);
+#endif
 	dma_free_coherent(dmab->dev.dev, dmab->bytes, dmab->area, dmab->addr);
 }
 
@@ -191,11 +204,13 @@ int snd_dma_alloc_pages(int type, struct device *device, size_t size,
 		dmab->dev.type = SNDRV_DMA_TYPE_DEV;
 #endif /* CONFIG_GENERIC_ALLOCATOR */
 	case SNDRV_DMA_TYPE_DEV:
+	case SNDRV_DMA_TYPE_DEV_UC:
 		snd_malloc_dev_pages(dmab, size);
 		break;
 #endif
 #ifdef CONFIG_SND_DMA_SGBUF
 	case SNDRV_DMA_TYPE_DEV_SG:
+	case SNDRV_DMA_TYPE_DEV_UC_SG:
 		snd_malloc_sgbuf_pages(device, size, dmab, NULL);
 		break;
 #endif
@@ -266,11 +281,13 @@ void snd_dma_free_pages(struct snd_dma_buffer *dmab)
 		break;
 #endif /* CONFIG_GENERIC_ALLOCATOR */
 	case SNDRV_DMA_TYPE_DEV:
+	case SNDRV_DMA_TYPE_DEV_UC:
 		snd_free_dev_pages(dmab);
 		break;
 #endif
 #ifdef CONFIG_SND_DMA_SGBUF
 	case SNDRV_DMA_TYPE_DEV_SG:
+	case SNDRV_DMA_TYPE_DEV_UC_SG:
 		snd_free_sgbuf_pages(dmab);
 		break;
 #endif

sound/core/sgbuf.c

@@ -23,6 +23,7 @@
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
 #include <linux/export.h>
+#include <asm/pgtable.h>
 #include <sound/memalloc.h>
 
 
@@ -43,6 +44,8 @@ int snd_free_sgbuf_pages(struct snd_dma_buffer *dmab)
 	dmab->area = NULL;
 
 	tmpb.dev.type = SNDRV_DMA_TYPE_DEV;
+	if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC_SG)
+		tmpb.dev.type = SNDRV_DMA_TYPE_DEV_UC;
 	tmpb.dev.dev = sgbuf->dev;
 	for (i = 0; i < sgbuf->pages; i++) {
 		if (!(sgbuf->table[i].addr & ~PAGE_MASK))
@@ -72,12 +75,20 @@ void *snd_malloc_sgbuf_pages(struct device *device,
 	struct snd_dma_buffer tmpb;
 	struct snd_sg_page *table;
 	struct page **pgtable;
+	int type = SNDRV_DMA_TYPE_DEV;
+	pgprot_t prot = PAGE_KERNEL;
 
 	dmab->area = NULL;
 	dmab->addr = 0;
 	dmab->private_data = sgbuf = kzalloc(sizeof(*sgbuf), GFP_KERNEL);
 	if (! sgbuf)
 		return NULL;
+	if (dmab->dev.type == SNDRV_DMA_TYPE_DEV_UC_SG) {
+		type = SNDRV_DMA_TYPE_DEV_UC;
+#ifdef pgprot_noncached
+		prot = pgprot_noncached(PAGE_KERNEL);
+#endif
+	}
 	sgbuf->dev = device;
 	pages = snd_sgbuf_aligned_pages(size);
 	sgbuf->tblsize = sgbuf_align_table(pages);
@@ -98,7 +109,7 @@ void *snd_malloc_sgbuf_pages(struct device *device,
 		if (chunk > maxpages)
 			chunk = maxpages;
 		chunk <<= PAGE_SHIFT;
-		if (snd_dma_alloc_pages_fallback(SNDRV_DMA_TYPE_DEV, device,
+		if (snd_dma_alloc_pages_fallback(type, device,
 						 chunk, &tmpb) < 0) {
 			if (!sgbuf->pages)
 				goto _failed;
@@ -125,7 +136,7 @@ void *snd_malloc_sgbuf_pages(struct device *device,
 	}
 
 	sgbuf->size = size;
-	dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, PAGE_KERNEL);
+	dmab->area = vmap(sgbuf->page_table, sgbuf->pages, VM_MAP, prot);
 	if (! dmab->area)
 		goto _failed;
 	if (res_size)