usb: add devicetree helpers for determining dr_mode and phy_type

This adds two little devicetree helper functions for determining the
dr_mode (host, peripheral, otg) and phy_type (utmi, ulpi,...) from
the devicetree.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/usb/phy.h b/include/linux/usb/phy.h
index 6b5978f..4403680 100644
--- a/include/linux/usb/phy.h
+++ b/include/linux/usb/phy.h
@@ -12,6 +12,15 @@
 #include <linux/notifier.h>
 #include <linux/usb.h>
 
+enum usb_phy_interface {
+	USBPHY_INTERFACE_MODE_UNKNOWN,
+	USBPHY_INTERFACE_MODE_UTMI,
+	USBPHY_INTERFACE_MODE_UTMIW,
+	USBPHY_INTERFACE_MODE_ULPI,
+	USBPHY_INTERFACE_MODE_SERIAL,
+	USBPHY_INTERFACE_MODE_HSIC,
+};
+
 enum usb_phy_events {
 	USB_EVENT_NONE,         /* no events or cable disconnected */
 	USB_EVENT_VBUS,         /* vbus valid event */