DMA_MEMORY_MAP

[JunningWu]

int
577		dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
578					    dma_addr_t device_addr, size_t size, int
579					    flags)
580	
581	Declare region of memory to be handed out by dma_alloc_coherent() when
582	it's asked for coherent memory for this device.
583	
584	phys_addr is the CPU physical address to which the memory is currently
585	assigned (this will be ioremapped so the CPU can access the region).
586	
587	device_addr is the DMA address the device needs to be programmed
588	with to actually address this memory (this will be handed out as the
589	dma_addr_t in dma_alloc_coherent()).
590	
591	size is the size of the area (must be multiples of PAGE_SIZE).
592	
593	flags can be ORed together and are:
594	
595	- DMA_MEMORY_EXCLUSIVE - only allocate memory from the declared regions.
596	  Do not allow dma_alloc_coherent() to fall back to system memory when
597	  it's out of memory in the declared region.
598	
599	As a simplification for the platforms, only *one* such region of
600	memory may be declared per device.
601	
602	For reasons of efficiency, most platforms choose to track the declared
603	region only at the granularity of a page.  For smaller allocations,
604	you should use the dma_pool() API.