phy: Add reset callback

The only use for this is for solving a hardware design problem in
usb of Rockchip RK3288.

Signed-off-by: Randy Li <[e-mail]>
Reviewed-by: Heiko Stuebner <[e-mail]>
Signed-off-by: Kishon Vijay Abraham I <[e-mail]>

drivers/phy/phy-core.c

···
 }
 EXPORT_SYMBOL_GPL(phy_set_mode);
 
+int phy_reset(struct phy *phy)
+{
+	int ret;
+
+	if (!phy || !phy->ops->reset)
+		return 0;
+
+	mutex_lock(&phy->mutex);
+	ret = phy->ops->reset(phy);
+	mutex_unlock(&phy->mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(phy_reset);
+
 /**
  * _of_phy_get() - lookup and obtain a reference to a phy by phandle
  * @np: device_node for which to get the phy

include/linux/phy/phy.h

···
  * @power_on: powering on the phy
  * @power_off: powering off the phy
  * @set_mode: set the mode of the phy
+ * @reset: resetting the phy
  * @owner: the module owner containing the ops
  */
 struct phy_ops {
···
 	int	(*power_on)(struct phy *phy);
 	int	(*power_off)(struct phy *phy);
 	int	(*set_mode)(struct phy *phy, enum phy_mode mode);
+	int	(*reset)(struct phy *phy);
 	struct module *owner;
 };
 
···
 int phy_power_on(struct phy *phy);
 int phy_power_off(struct phy *phy);
 int phy_set_mode(struct phy *phy, enum phy_mode mode);
+int phy_reset(struct phy *phy);
 static inline int phy_get_bus_width(struct phy *phy)
 {
 	return phy->attrs.bus_width;