dma-mapping: turn dma_cache_sync into a dma_map_ops method

After we removed all the dead wood it turns out only two architectures
actually implement dma_cache_sync as a real op: mips and parisc.  Add
a cache_sync method to struct dma_map_ops and implement it for the
mips defualt DMA ops, and the parisc pa11 ops.

Note that arm, arc and openrisc support DMA_ATTR_NON_CONSISTENT, but
never provided a functional dma_cache_sync implementations, which
seems somewhat odd.

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

arch/unicore32/include/asm/dma-mapping.h

@@ -45,10 +45,5 @@ static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 
 static inline void dma_mark_clean(void *addr, size_t size) {}
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr,
-		size_t size, enum dma_data_direction direction)
-{
-}
-
 #endif /* __KERNEL__ */
 #endif

arch/x86/include/asm/dma-mapping.h

@@ -67,12 +67,6 @@ static inline phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
 }
 #endif /* CONFIG_X86_DMA_REMAP */
 
-static inline void
-dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-	enum dma_data_direction dir)
-{
-}
-
 static inline unsigned long dma_alloc_coherent_mask(struct device *dev,
 						    gfp_t gfp)
 {

arch/xtensa/include/asm/dma-mapping.h

@@ -23,11 +23,6 @@ static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
 	return &xtensa_dma_map_ops;
 }
 
-static inline void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
-		    enum dma_data_direction direction)
-{
-}
-
 static inline dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
 {
 	return (dma_addr_t)paddr;

include/linux/dma-mapping.h

@@ -126,6 +126,8 @@ struct dma_map_ops {
 	void (*sync_sg_for_device)(struct device *dev,
 				   struct scatterlist *sg, int nents,
 				   enum dma_data_direction dir);
+	void (*cache_sync)(struct device *dev, void *vaddr, size_t size,
+			enum dma_data_direction direction);
 	int (*mapping_error)(struct device *dev, dma_addr_t dma_addr);
 	int (*dma_supported)(struct device *dev, u64 mask);
 #ifdef ARCH_HAS_DMA_GET_REQUIRED_MASK
@@ -436,6 +438,17 @@ dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 #define dma_map_page(d, p, o, s, r) dma_map_page_attrs(d, p, o, s, r, 0)
 #define dma_unmap_page(d, a, s, r) dma_unmap_page_attrs(d, a, s, r, 0)
 
+static inline void
+dma_cache_sync(struct device *dev, void *vaddr, size_t size,
+		enum dma_data_direction dir)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+
+	BUG_ON(!valid_dma_direction(dir));
+	if (ops->cache_sync)
+		ops->cache_sync(dev, vaddr, size, dir);
+}
+
 extern int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 			   void *cpu_addr, dma_addr_t dma_addr, size_t size);