usb: phy: Add set_wakeup API

This API is used to set wakeup enable at PHY registers, in that
case, the PHY can be waken up from suspend due to external events,
like vbus change, dp/dm change and id change.
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

include/linux/usb/phy.h

@@ -111,6 +111,13 @@ struct usb_phy {
 	int	(*set_suspend)(struct usb_phy *x,
 				int suspend);
 
+	/*
+	 * Set wakeup enable for PHY, in that case, the PHY can be
+	 * woken up from suspend status due to external events,
+	 * like vbus change, dp/dm change and id.
+	 */
+	int	(*set_wakeup)(struct usb_phy *x, bool enabled);
+
 	/* notify phy connect status change */
 	int	(*notify_connect)(struct usb_phy *x,
 			enum usb_device_speed speed);
@@ -264,6 +271,15 @@ usb_phy_set_suspend(struct usb_phy *x, int suspend)
 		return 0;
 }
 
+static inline int
+usb_phy_set_wakeup(struct usb_phy *x, bool enabled)
+{
+	if (x && x->set_wakeup)
+		return x->set_wakeup(x, enabled);
+	else
+		return 0;
+}
+
 static inline int
 usb_phy_notify_connect(struct usb_phy *x, enum usb_device_speed speed)
 {