[PATCH] USB OTG: add usb_bus_start_enum() (1/5)

Define a new usb_bus_start_enum() routine that's available with OTG.
It starts immediate enumeration (port reset) and makes khubd wake up
later.  Non-OTG code could start to use this, given some attention to
HC-specific reset timing issues.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/usb/core/hcd.c

@@ -1404,6 +1404,45 @@ static int hcd_hub_resume (struct usb_bus *bus)
 
 /*-------------------------------------------------------------------------*/
 
+#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
+
+/*-------------------------------------------------------------------------*/
+
 /* called by khubd, rmmod, apmd, or other thread for hcd-private cleanup.
  * we're guaranteed that the device is fully quiesced.  also, that each
  * endpoint has been hcd_endpoint_disabled.

drivers/usb/core/hcd.h

@@ -212,6 +212,7 @@ struct hc_driver {
 				char *buf, u16 wLength);
 	int		(*hub_suspend)(struct usb_hcd *);
 	int		(*hub_resume)(struct usb_hcd *);
+	int		(*start_port_reset)(struct usb_hcd *, unsigned port_num);
 };
 
 extern void usb_hcd_giveback_urb (struct usb_hcd *hcd, struct urb *urb, struct pt_regs *regs);

include/linux/usb_otg.h

@@ -114,3 +114,5 @@ otg_start_srp(struct otg_transceiver *otg)
 }
 
 
+/* for OTG controller drivers (and maybe other stuff) */
+extern int usb_bus_start_enum(struct usb_bus *bus, unsigned port_num);