net: phy: add genphy_c45_check_and_restart_aneg

This function will be used by config_aneg callback implementations of
PHY drivers and allows to reduce boilerplate code.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy-c45.c

@@ -156,6 +156,36 @@ int genphy_c45_restart_aneg(struct phy_device *phydev)
 }
 EXPORT_SYMBOL_GPL(genphy_c45_restart_aneg);
 
+/**
+ * genphy_c45_check_and_restart_aneg - Enable and restart auto-negotiation
+ * @phydev: target phy_device struct
+ * @restart: whether aneg restart is requested
+ *
+ * This assumes that the auto-negotiation MMD is present.
+ *
+ * Check, and restart auto-negotiation if needed.
+ */
+int genphy_c45_check_and_restart_aneg(struct phy_device *phydev, bool restart)
+{
+	int ret = 0;
+
+	if (!restart) {
+		/* Configure and restart aneg if it wasn't set before */
+		ret = phy_read_mmd(phydev, MDIO_MMD_AN, MDIO_CTRL1);
+		if (ret < 0)
+			return ret;
+
+		if (!(ret & MDIO_AN_CTRL1_ENABLE))
+			restart = true;
+	}
+
+	if (restart)
+		ret = genphy_c45_restart_aneg(phydev);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(genphy_c45_check_and_restart_aneg);
+
 /**
  * genphy_c45_aneg_done - return auto-negotiation complete status
  * @phydev: target phy_device struct

include/linux/phy.h

@@ -1097,6 +1097,7 @@ int genphy_write_mmd_unsupported(struct phy_device *phdev, int devnum,
 
 /* Clause 45 PHY */
 int genphy_c45_restart_aneg(struct phy_device *phydev);
+int genphy_c45_check_and_restart_aneg(struct phy_device *phydev, bool restart);
 int genphy_c45_aneg_done(struct phy_device *phydev);
 int genphy_c45_read_link(struct phy_device *phydev);
 int genphy_c45_read_lpa(struct phy_device *phydev);