phy: add new phy_notify_state() api

Add a new phy_notify_state() api that notifies and configures a phy for a
given state transition.

This is intended to be used by phy drivers which need to do some runtime
configuration of parameters that can't be handled by phy_calibrate() or
phy_power_{on|off}().

The first usage of this API is in the Samsung UFS phy that needs to issue
some register writes when entering and exiting the hibernate link state.

Signed-off-by: Peter Griffin <[e-mail]>
Reviewed-by: Neil Armstrong <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/phy/phy-core.c

···
 EXPORT_SYMBOL_GPL(phy_notify_disconnect);
 
 /**
+ * phy_notify_state() - phy state notification
+ * @phy: the PHY returned by phy_get()
+ * @state: the PHY state
+ *
+ * Notify the PHY of a state transition. Used to notify and
+ * configure the PHY accordingly.
+ *
+ * Returns: %0 if successful, a negative error code otherwise
+ */
+int phy_notify_state(struct phy *phy, union phy_notify state)
+{
+	int ret;
+
+	if (!phy || !phy->ops->notify_phystate)
+		return 0;
+
+	mutex_lock(&phy->mutex);
+	ret = phy->ops->notify_phystate(phy, state);
+	mutex_unlock(&phy->mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(phy_notify_state);
+
+/**
  * phy_configure() - Changes the phy parameters
  * @phy: the phy returned by phy_get()
  * @opts: New configuration to apply

include/linux/phy/phy.h

···
 	PHY_MEDIA_DAC,
 };
 
+enum phy_ufs_state {
+	PHY_UFS_HIBERN8_ENTER,
+	PHY_UFS_HIBERN8_EXIT,
+};
+
+union phy_notify {
+	enum phy_ufs_state ufs_state;
+};
+
 /**
  * union phy_configure_opts - Opaque generic phy configuration
  *
···
  * @set_speed: set the speed of the phy (optional)
  * @reset: resetting the phy
  * @calibrate: calibrate the phy
+ * @notify_phystate: notify and configure the phy for a particular state
  * @release: ops to be performed while the consumer relinquishes the PHY
  * @owner: the module owner containing the ops
  */
···
 	int	(*connect)(struct phy *phy, int port);
 	int	(*disconnect)(struct phy *phy, int port);
 
+	int	(*notify_phystate)(struct phy *phy, union phy_notify state);
 	void	(*release)(struct phy *phy);
 	struct module *owner;
 };
···
 int phy_calibrate(struct phy *phy);
 int phy_notify_connect(struct phy *phy, int port);
 int phy_notify_disconnect(struct phy *phy, int port);
+int phy_notify_state(struct phy *phy, union phy_notify state);
 static inline int phy_get_bus_width(struct phy *phy)
 {
 	return phy->attrs.bus_width;
···
 }
 
 static inline int phy_notify_disconnect(struct phy *phy, int index)
+{
+	if (!phy)
+		return 0;
+	return -ENOSYS;
+}
+
+static inline int phy_notify_state(struct phy *phy, union phy_notify state)
 {
 	if (!phy)
 		return 0;