[RFC] dma-mapping: Provide write-combine allocations

[Thierry Reding <thierry.reding@gmail.com>]

Provide an implementation for dma_{alloc,free}_writecombine() when the
architecture supports DMA attributes.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 arch/arm/include/asm/dma-mapping.h | 16 ----------------
 include/linux/dma-mapping.h        | 16 ++++++++++++++++
 2 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
index e701a4d9aa59..96b7634a7edc 100644
--- a/arch/arm/include/asm/dma-mapping.h
+++ b/arch/arm/include/asm/dma-mapping.h
@@ -242,22 +242,6 @@ extern int arm_dma_mmap(struct device *dev, struct vm_area_struct *vma,
 			void *cpu_addr, dma_addr_t dma_addr, size_t size,
 			struct dma_attrs *attrs);
 
-static inline void *dma_alloc_writecombine(struct device *dev, size_t size,
-				       dma_addr_t *dma_handle, gfp_t flag)
-{
-	DEFINE_DMA_ATTRS(attrs);
-	dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);
-	return dma_alloc_attrs(dev, size, dma_handle, flag, &attrs);
-}
-
-static inline void dma_free_writecombine(struct device *dev, size_t size,
-				     void *cpu_addr, dma_addr_t dma_handle)
-{
-	DEFINE_DMA_ATTRS(attrs);
-	dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);
-	return dma_free_attrs(dev, size, cpu_addr, dma_handle, &attrs);
-}
-
 /*
  * This can be called during early boot to increase the size of the atomic
  * coherent DMA pool above the default value of 256KiB. It must be called
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index fd4aee29ad10..8475e02b4bd1 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -249,6 +249,22 @@ struct dma_attrs;
 #define dma_unmap_sg_attrs(dev, sgl, nents, dir, attrs) \
 	dma_unmap_sg(dev, sgl, nents, dir)
 
+#else
+static inline void *dma_alloc_writecombine(struct device *dev, size_t size,
+					   dma_addr_t *dma_addr, gfp_t gfp)
+{
+	DEFINE_DMA_ATTRS(attrs);
+	dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);
+	return dma_alloc_attrs(dev, size, dma_addr, gfp, &attrs);
+}
+
+static inline void dma_free_writecombine(struct device *dev, size_t size,
+					 void *cpu_addr, dma_addr_t dma_addr)
+{
+	DEFINE_DMA_ATTRS(attrs);
+	dma_set_attr(DMA_ATTR_WRITE_COMBINE, &attrs);
+	return dma_free_attrs(dev, size, cpu_addr, dma_addr, &attrs);
+}
 #endif /* CONFIG_HAVE_DMA_ATTRS */
 
 #ifdef CONFIG_NEED_DMA_MAP_STATE
-- 
1.8.4.2