/* mapping and unmapping functions for the IOMMU MMIO space. Each AMD IOMMU in the system has one.  */
static u8* __init iommu_map_mmio_space(u64 address)
/* mapping and unmapping functions for the IOMMU MMIO space. Each AMD IOMMU in the system has one.  */
static u8* __init iommu_map_mmio_space(u64 address)
{
	u8 *ret;
	if (!request_mem_region(address, MMIO_REGION_LENGTH, "amd_iommu"))
		return NULL;
	ret = ioremap_nocache(address, MMIO_REGION_LENGTH);
	if (ret != NULL)
		return ret;
	release_mem_region(address, MMIO_REGION_LENGTH);
	return NULL;
}