1 files changed, 31 insertions, 0 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 30b064497486..3343264f5105 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -34,6 +34,37 @@ void register_iommu(struct iommu_ops *ops)
         iommu_ops = ops;
 }
 
+static void iommu_bus_init(struct bus_type *bus, struct iommu_ops *ops)
+{
+}
+
+/**
+ * bus_set_iommu - set iommu-callbacks for the bus
+ * @bus: bus.
+ * @ops: the callbacks provided by the iommu-driver
+ *
+ * This function is called by an iommu driver to set the iommu methods
+ * used for a particular bus. Drivers for devices on that bus can use
+ * the iommu-api after these ops are registered.
+ * This special function is needed because IOMMUs are usually devices on
+ * the bus itself, so the iommu drivers are not initialized when the bus
+ * is set up. With this function the iommu-driver can set the iommu-ops
+ * afterwards.
+ */
+int bus_set_iommu(struct bus_type *bus, struct iommu_ops *ops)
+{
+        if (bus->iommu_ops != NULL)
+                return -EBUSY;
+
+        bus->iommu_ops = ops;
+
+        /* Do IOMMU specific setup for this bus-type */
+        iommu_bus_init(bus, ops);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(bus_set_iommu);
+
 bool iommu_found(void)
 {
         return iommu_ops != NULL;