iommu/amd: Add basic debugfs infrastructure for AMD IOMMU

Implement a skeleton framework for debugfs support in the AMD
IOMMU.  Add an AMD-specific Kconfig boolean that depends upon
general enablement of DebugFS in the IOMMU.

Signed-off-by: Gary R Hook <[email protected]>
Signed-off-by: Joerg Roedel <[email protected]>
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index ab9181d..8d0a288 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -145,6 +145,18 @@
 	  hardware. Select this option if you want to use devices that support
 	  the PCI PRI and PASID interface.
 
+config AMD_IOMMU_DEBUGFS
+	bool "Enable AMD IOMMU internals in DebugFS"
+	depends on AMD_IOMMU && IOMMU_DEBUGFS
+	---help---
+	  !!!WARNING!!!  !!!WARNING!!!  !!!WARNING!!!  !!!WARNING!!!
+
+	  DO NOT ENABLE THIS OPTION UNLESS YOU REALLY, -REALLY- KNOW WHAT YOU ARE DOING!!!
+	  Exposes AMD IOMMU device internals in DebugFS.
+
+	  This option is -NOT- intended for production environments, and should
+	  not generally be enabled.
+
 # Intel IOMMU support
 config DMAR_TABLE
 	bool