iommu/amd: Add amd_iommu_domain_direct_map function

This function can be used to switch a domain into
paging-mode 0. In this mode all devices can access physical
system memory directly without any remapping.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/drivers/iommu/amd_iommu_proto.h b/drivers/iommu/amd_iommu_proto.h
index cfe2dfc..2c4554e 100644
--- a/drivers/iommu/amd_iommu_proto.h
+++ b/drivers/iommu/amd_iommu_proto.h
@@ -33,9 +33,12 @@
 extern void amd_iommu_init_api(void);
 
 /* IOMMUv2 specific functions */
+struct iommu_domain;
+
 extern bool amd_iommu_v2_supported(void);
 extern int amd_iommu_register_ppr_notifier(struct notifier_block *nb);
 extern int amd_iommu_unregister_ppr_notifier(struct notifier_block *nb);
+extern void amd_iommu_domain_direct_map(struct iommu_domain *dom);
 
 #ifndef CONFIG_AMD_IOMMU_STATS