iommu/amd: Add driver stub for AMD IOMMUv2 support

Add a Kconfig option for the optional driver. Since it is
optional it can be compiled as a module and will only be
loaded when required by another driver.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 220dfc2..e608a36 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -60,6 +60,14 @@
 	  information to userspace via debugfs.
 	  If unsure, say N.
 
+config AMD_IOMMU_V2
+	tristate "AMD IOMMU Version 2 driver (EXPERIMENTAL)"
+	depends on AMD_IOMMU && EXPERIMENTAL
+	---help---
+	  This option enables support for the AMD IOMMUv2 features of the IOMMU
+	  hardware. Select this option if you want to use devices that support
+	  the the PCI PRI and PASID interface.
+
 # Intel IOMMU support
 config DMAR_TABLE
 	bool