AMD IOMMU: add MSI interrupt support

The AMD IOMMU can generate interrupts for various reasons. This patch
adds the basic interrupt enabling infrastructure to the driver.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 15792ed..0e494b9 100644
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -51,6 +51,17 @@
 
 /****************************************************************************
  *
+ * Interrupt handling functions
+ *
+ ****************************************************************************/
+
+irqreturn_t amd_iommu_int_handler(int irq, void *data)
+{
+	return IRQ_NONE;
+}
+
+/****************************************************************************
+ *
  * IOMMU command queuing functions
  *
  ****************************************************************************/