usb: ehci: add ehci_port_power interface

The current EHCI implementation is prepared to toggle the
PORT_POWER bit to enable or disable a USB-Port. In some
cases this port power can not be just toggled by the PORT_POWER
bit, and the gpio-regulator is needed to be toggled too.

This patch defines a port power control interface ehci_port_power for
ehci core use, it toggles PORT_POWER bit as well as calls platform
defined .port_power if it is defined.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Acked-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index cd96a2b..9cf7e35 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -379,6 +379,9 @@
 	int	(*disable_usb3_lpm_timeout)(struct usb_hcd *,
 			struct usb_device *, enum usb3_link_state state);
 	int	(*find_raw_port_number)(struct usb_hcd *, int);
+	/* Call for power on/off the port if necessary */
+	int	(*port_power)(struct usb_hcd *hcd, int portnum, bool enable);
+
 };
 
 static inline int hcd_giveback_urb_in_bh(struct usb_hcd *hcd)