amd-iommu: implement suspend/resume

This patch puts everything together and enables suspend/resume support
in the AMD IOMMU driver.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

arch/x86/kernel/amd_iommu_init.c

@@ -965,12 +965,31 @@ static void disable_iommus(void)
 
 static int amd_iommu_resume(struct sys_device *dev)
 {
+	/*
+	 * Disable IOMMUs before reprogramming the hardware registers.
+	 * IOMMU is still enabled from the resume kernel.
+	 */
+	disable_iommus();
+
+	/* re-load the hardware */
+	enable_iommus();
+
+	/*
+	 * we have to flush after the IOMMUs are enabled because a
+	 * disabled IOMMU will never execute the commands we send
+	 */
+	amd_iommu_flush_all_domains();
+	amd_iommu_flush_all_devices();
+
 	return 0;
 }
 
 static int amd_iommu_suspend(struct sys_device *dev, pm_message_t state)
 {
-	return -EINVAL;
+	/* disable IOMMUs to go out of the way for BIOS */
+	disable_iommus();
+
+	return 0;
 }
 
 static struct sysdev_class amd_iommu_sysdev_class = {