Memory Management Helpers

copy_to_user_fromio - copy data from mmio-space to user-space
copy_from_user_toio - copy data from user-space to mmio-space
snd_malloc_pages - allocate pages with the given size
snd_free_pages - release the pages
snd_dma_alloc_pages - allocate the buffer area according to the given type
snd_dma_alloc_pages_fallback - allocate the buffer area according to the given type with fallback
snd_dma_free_pages - release the allocated buffer
snd_dma_get_reserved_buf - get the reserved buffer for the given device
snd_dma_reserve_buf - reserve the buffer