Commit 427ae268 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: core: Add device-managed page allocator helper 

This is a preparation for allowing devres usages more widely in
various sound drivers.  As a first step, this patch adds a new
allocator function, snd_devm_alloc_pages(), to manage the allocated
pages via devres, so that the pages will be automagically released as
device unbinding.

Unlike the old snd_dma_alloc_pages(), the new function returns
directly the snd_dma_buffer pointer.  The caller needs NULL-check for
the allocation error appropriately.

Also, since a real device pointer is mandatory for devres,
SNDRV_DMA_TYPE_CONTINUOUS or SNDRV_DMA_TYPE_VMALLOC type can't be used
for this function.

Link: https://lore.kernel.org/r/20210715075941.23332-2-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent e6c0a088

include/sound/memalloc.h

+4 −0
Original line number Diff line number Diff line
@@ -79,5 +79,9 @@ struct page *snd_sgbuf_get_page(struct snd_dma_buffer *dmab, size_t offset); 
unsigned int snd_sgbuf_get_chunk_size(struct snd_dma_buffer *dmab,

				      unsigned int ofs, unsigned int size);



/* device-managed memory allocator */

struct snd_dma_buffer *snd_devm_alloc_pages(struct device *dev, int type,

					    size_t size);



#endif /* __SOUND_MEMALLOC_H */

sound/core/memalloc.c

+46 −0
Original line number Diff line number Diff line
@@ -127,6 +127,52 @@ void snd_dma_free_pages(struct snd_dma_buffer *dmab) 
}

EXPORT_SYMBOL(snd_dma_free_pages);



/* called by devres */

static void __snd_release_pages(struct device *dev, void *res)

{

	snd_dma_free_pages(res);

}



/**

 * snd_devm_alloc_pages - allocate the buffer and manage with devres

 * @dev: the device pointer

 * @type: the DMA buffer type

 * @size: the buffer size to allocate

 *

 * Allocate buffer pages depending on the given type and manage using devres.

 * The pages will be released automatically at the device removal.

 *

 * Unlike snd_dma_alloc_pages(), this function requires the real device pointer,

 * hence it can't work with SNDRV_DMA_TYPE_CONTINUOUS or

 * SNDRV_DMA_TYPE_VMALLOC type.

 *

 * The function returns the snd_dma_buffer object at success, or NULL if failed.

 */

struct snd_dma_buffer *

snd_devm_alloc_pages(struct device *dev, int type, size_t size)

{

	struct snd_dma_buffer *dmab;

	int err;



	if (WARN_ON(type == SNDRV_DMA_TYPE_CONTINUOUS ||

		    type == SNDRV_DMA_TYPE_VMALLOC))

		return NULL;



	dmab = devres_alloc(__snd_release_pages, sizeof(*dmab), GFP_KERNEL);

	if (!dmab)

		return NULL;



	err = snd_dma_alloc_pages(type, dev, size, dmab);

	if (err < 0) {

		devres_free(dmab);

		return NULL;

	}



	devres_add(dev, dmab);

	return dmab;

}

EXPORT_SYMBOL_GPL(snd_devm_alloc_pages);



/**

 * snd_dma_buffer_mmap - perform mmap of the given DMA buffer

 * @dmab: buffer allocation information