void *dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp);
int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
void *dma_alloc_coherent(struct device *dev, size_t size,
dma_addr_t *dma_handle, gfp_t gfp);
int dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,