x86, AMD IOMMU: disable suspend/resume with IOMMU enabled (for now)

This patch disables suspend/resume on machines with AMD IOMMU enabled. Real
suspend/resume support for AMD IOMMU is currently being worked on. Until this
is ready it will be disabled to avoid data corruption when the IOMMU is not
properly re-enabled at resume. The patch is based on a similar patch for the
GART driver written by Pavel Machek.

The overall driver merged into tip/master is tested with parallel disk and
network loads and showed no problems in a test running for 3 days.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Cc: iommu@lists.linux-foundation.org
Cc: bhavna.sarathy@amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/amd_iommu_init.c

@@ -21,6 +21,7 @@
 #include <linux/acpi.h>
 #include <linux/gfp.h>
 #include <linux/list.h>
+#include <linux/sysdev.h>
 #include <asm/pci-direct.h>
 #include <asm/amd_iommu_types.h>
 #include <asm/amd_iommu.h>
@@ -654,6 +655,32 @@ static void __init enable_iommus(void)
 	}
 }
 
+/*
+ * Suspend/Resume support
+ * disable suspend until real resume implemented
+ */
+
+static int amd_iommu_resume(struct sys_device *dev)
+{
+	return 0;
+}
+
+static int amd_iommu_suspend(struct sys_device *dev, pm_message_t state)
+{
+	return -EINVAL;
+}
+
+static struct sysdev_class amd_iommu_sysdev_class = {
+	.name = "amd_iommu",
+	.suspend = amd_iommu_suspend,
+	.resume = amd_iommu_resume,
+};
+
+static struct sys_device device_amd_iommu = {
+	.id = 0,
+	.cls = &amd_iommu_sysdev_class,
+};
+
 int __init amd_iommu_init(void)
 {
 	int i, ret = 0;
@@ -745,6 +772,14 @@ int __init amd_iommu_init(void)
 	if (ret)
 		goto free;
 
+	ret = sysdev_class_register(&amd_iommu_sysdev_class);
+	if (ret)
+		goto free;
+
+	ret = sysdev_register(&device_amd_iommu);
+	if (ret)
+		goto free;
+
 	enable_iommus();
 
 	printk(KERN_INFO "AMD IOMMU: aperture size is %d MB\n",