1. 根目录:
2. arch
3. frv
4. include
5. asm
6. dma-mapping.h

#ifndef _ASM_DMA_MAPPING_H
#define _ASM_DMA_MAPPING_H

#include <linux/device.h>
#include <asm/cache.h>
#include <asm/cacheflush.h>
#include <asm/scatterlist.h>
#include <asm/io.h>

/*
 * See Documentation/DMA-API.txt for the description of how the
 * following DMA API should work.
 */

#define dma_alloc_noncoherent(d, s, h, f) dma_alloc_coherent(d, s, h, f)
#define dma_free_noncoherent(d, s, v, h) dma_free_coherent(d, s, v, h)

extern unsigned long __nongprelbss dma_coherent_mem_start;
extern unsigned long __nongprelbss dma_coherent_mem_end;

void *dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp);
void dma_free_coherent(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_handle);

extern dma_addr_t dma_map_single(struct device *dev, void *ptr, size_t size,
				 enum dma_data_direction direction);

static inline
void dma_unmap_single(struct device *dev, dma_addr_t dma_addr, size_t size,
		      enum dma_data_direction direction)
{
	BUG_ON(direction == DMA_NONE);
}

extern int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
		      enum dma_data_direction direction);

static inline
void dma_unmap_sg(struct device *dev, struct scatterlist *sg, int nhwentries,
	     enum dma_data_direction direction)
{
	BUG_ON(direction == DMA_NONE);
}

extern
dma_addr_t dma_map_page(struct device *dev, struct page *page, unsigned long offset,
			size_t size, enum dma_data_direction direction);

static inline
void dma_unmap_page(struct device *dev, dma_addr_t dma_address, size_t size,
		    enum dma_data_direction direction)
{
	BUG_ON(direction == DMA_NONE);
}


static inline
void dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size,
			     enum dma_data_direction direction)
{
}

static inline
void dma_sync_single_for_device(struct device *dev, dma_addr_t dma_handle, size_t size,
				enum dma_data_direction direction)
{
	flush_write_buffers();
}

static inline
void dma_sync_single_range_for_cpu(struct device *dev, dma_addr_t dma_handle,
				   unsigned long offset, size_t size,
				   enum dma_data_direction direction)
{
}

static inline
void dma_sync_single_range_for_device(struct device *dev, dma_addr_t dma_handle,
				      unsigned long offset, size_t size,
				      enum dma_data_direction direction)
{
	flush_write_buffers();
}

static inline
void dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg, int nelems,
			 enum dma_data_direction direction)
{
}

static inline
void dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg, int nelems,
			    enum dma_data_direction direction)
{
	flush_write_buffers();
}

static inline
int dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
{
	return 0;
}

static inline
int dma_supported(struct device *dev, u64 mask)
{
        /*
         * we fall back to GFP_DMA when the mask isn't all 1s,
         * so we can't guarantee allocations that must be
         * within a tighter range than GFP_DMA..
         */
        if (mask < 0x00ffffff)
                return 0;

	return 1;
}

static inline
int dma_set_mask(struct device *dev, u64 mask)
{
	if (!dev->dma_mask || !dma_supported(dev, mask))
		return -EIO;

	*dev->dma_mask = mask;

	return 0;
}

static inline
void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
		    enum dma_data_direction direction)
{
	flush_write_buffers();
}

#endif  /* _ASM_DMA_MAPPING_H */