ALSA: memalloc: Add vmalloc buffer allocation support

This patch adds the vmalloc buffer support to ALSA memalloc core.  A
new type, SNDRV_DMA_TYPE_VMALLOC was added.

The vmalloc buffer has been already supported in the PCM via a few own
helper functions, but the user sometimes get confused and misuse
them.  With this patch, the whole buffer management is integrated into
the memalloc core, so they can be used in a sole common way.

Link: https://lore.kernel.org/r/20191105080138.1260-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/memalloc.h

@@ -44,6 +44,7 @@ struct snd_dma_device {
 #else
 #define SNDRV_DMA_TYPE_DEV_IRAM	SNDRV_DMA_TYPE_DEV
 #endif
+#define SNDRV_DMA_TYPE_VMALLOC		7	/* vmalloc'ed buffer */
 
 /*
  * info for buffer allocation

sound/core/memalloc.c

@@ -10,6 +10,7 @@
 #include <linux/mm.h>
 #include <linux/dma-mapping.h>
 #include <linux/genalloc.h>
+#include <linux/vmalloc.h>
 #ifdef CONFIG_X86
 #include <asm/set_memory.h>
 #endif
@@ -99,10 +100,11 @@ static void snd_free_dev_iram(struct snd_dma_buffer *dmab)
  *
  */
 
-static inline gfp_t snd_mem_get_gfp_flags(const struct device *dev)
+static inline gfp_t snd_mem_get_gfp_flags(const struct device *dev,
+					  gfp_t default_gfp)
 {
 	if (!dev)
-		return GFP_KERNEL;
+		return default_gfp;
 	else
 		return (__force gfp_t)(unsigned long)dev;
 }
@@ -123,6 +125,8 @@ static inline gfp_t snd_mem_get_gfp_flags(const struct device *dev)
 int snd_dma_alloc_pages(int type, struct device *device, size_t size,
 			struct snd_dma_buffer *dmab)
 {
+	gfp_t gfp;
+
 	if (WARN_ON(!size))
 		return -ENXIO;
 	if (WARN_ON(!dmab))
@@ -133,8 +137,13 @@ int snd_dma_alloc_pages(int type, struct device *device, size_t size,
 	dmab->bytes = 0;
 	switch (type) {
 	case SNDRV_DMA_TYPE_CONTINUOUS:
-		dmab->area = alloc_pages_exact(size,
-					       snd_mem_get_gfp_flags(device));
+		gfp = snd_mem_get_gfp_flags(device, GFP_KERNEL);
+		dmab->area = alloc_pages_exact(size, gfp);
+		dmab->addr = 0;
+		break;
+	case SNDRV_DMA_TYPE_VMALLOC:
+		gfp = snd_mem_get_gfp_flags(device, GFP_KERNEL | __GFP_HIGHMEM);
+		dmab->area = __vmalloc(size, gfp, PAGE_KERNEL);
 		dmab->addr = 0;
 		break;
 #ifdef CONFIG_HAS_DMA
@@ -220,6 +229,9 @@ void snd_dma_free_pages(struct snd_dma_buffer *dmab)
 	case SNDRV_DMA_TYPE_CONTINUOUS:
 		free_pages_exact(dmab->area, dmab->bytes);
 		break;
+	case SNDRV_DMA_TYPE_VMALLOC:
+		vfree(dmab->area);
+		break;
 #ifdef CONFIG_HAS_DMA
 #ifdef CONFIG_GENERIC_ALLOCATOR
 	case SNDRV_DMA_TYPE_DEV_IRAM: