+#ifdef CONFIG_USB_OTG
+
+/**
+ * usb_bus_start_enum - start immediate enumeration (for OTG)
+ * @bus: the bus (must use hcd framework)
+ * @port: 1-based number of port; usually bus->otg_port
+ * Context: in_interrupt()
+ *
+ * Starts enumeration, with an immediate reset followed later by
+ * khubd identifying and possibly configuring the device.
+ * This is needed by OTG controller drivers, where it helps meet
+ * HNP protocol timing requirements for starting a port reset.
+ */
+int usb_bus_start_enum(struct usb_bus *bus, unsigned port_num)
+{
+ struct usb_hcd *hcd;
+ int status = -EOPNOTSUPP;
+
+ /* NOTE: since HNP can't start by grabbing the bus's address0_sem,
+ * boards with root hubs hooked up to internal devices (instead of
+ * just the OTG port) may need more attention to resetting...
+ */
+ hcd = container_of (bus, struct usb_hcd, self);
+ if (port_num && hcd->driver->start_port_reset)
+ status = hcd->driver->start_port_reset(hcd, port_num);
+
+ /* run khubd shortly after (first) root port reset finishes;
+ * it may issue others, until at least 50 msecs have passed.
+ */
+ if (status == 0)
+ mod_timer(&hcd->rh_timer, jiffies + msecs_to_jiffies(10));
+ return status;
+}
+EXPORT_SYMBOL (usb_bus_start_enum);
+
+#endif
+
+/*-------------------------------------------------------------------------*/
+