dma-direct: add support for CMA allocation

Try the CMA allocator for coherent allocations if supported.

Roughly modelled after the x86 code.

Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/lib/dma-direct.c b/lib/dma-direct.c
index 32fd4d9..a9ae98b 100644 (file)
--- a/lib/dma-direct.c
+++ b/lib/dma-direct.c
@@ -7,6 +7,7 @@
 #include <linux/mm.h>
 #include <linux/dma-direct.h>
 #include <linux/scatterlist.h>
+#include <linux/dma-contiguous.h>
 #include <linux/pfn.h>
 
 #define DIRECT_MAPPING_ERROR           0
@@ -29,19 +30,30 @@ check_addr(struct device *dev, dma_addr_t dma_addr, size_t size,
 static void *dma_direct_alloc(struct device *dev, size_t size,
                dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
 {
-       void *ret;
+       unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+       int page_order = get_order(size);
+       struct page *page = NULL;
 
-       ret = (void *)__get_free_pages(gfp, get_order(size));
-       if (ret)
-               *dma_handle = phys_to_dma(dev, virt_to_phys(ret));
+       /* CMA can be used only in the context which permits sleeping */
+       if (gfpflags_allow_blocking(gfp))
+               page = dma_alloc_from_contiguous(dev, count, page_order, gfp);
+       if (!page)
+               page = alloc_pages(gfp, page_order);
+       if (!page)
+               return NULL;
 
-       return ret;
+       *dma_handle = phys_to_dma(dev, page_to_phys(page));
+       memset(page_address(page), 0, size);
+       return page_address(page);
 }
 
 static void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
                dma_addr_t dma_addr, unsigned long attrs)
 {
-       free_pages((unsigned long)cpu_addr, get_order(size));
+       unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+       if (!dma_release_from_contiguous(dev, virt_to_page(cpu_addr), count))
+               free_pages((unsigned long)cpu_addr, get_order(size));
 }
 
 static dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,