dma-mapping: move the arm64 noncoherent alloc/free support to common code

The arm64 codebase to implement coherent dma allocation for architectures
with non-coherent DMA is a good start for a generic implementation, given
that is uses the generic remap helpers, provides the atomic pool for
allocations that can't sleep and still is realtively simple and well
tested.  Move it to kernel/dma and allow architectures to opt into it
using a config symbol.  Architectures just need to provide a new
arch_dma_prep_coherent helper to writeback an invalidate the caches
for any memory that gets remapped for uncached access.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 0f81c713f6e9..1a0edcde7d14 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -455,6 +455,11 @@ void *dma_common_pages_remap(struct page **pages, size_t size,
 			const void *caller);
 void dma_common_free_remap(void *cpu_addr, size_t size, unsigned long vm_flags);
 
+int __init dma_atomic_pool_init(gfp_t gfp, pgprot_t prot);
+bool dma_in_atomic_pool(void *start, size_t size);
+void *dma_alloc_from_pool(size_t size, struct page **ret_page, gfp_t flags);
+bool dma_free_from_pool(void *start, size_t size);
+
 /**
  * dma_mmap_attrs - map a coherent DMA allocation into user space
  * @dev: valid struct device pointer, or NULL for ISA and EISA-like devices