cpsw: ethtool: add support for nway reset

This patch adds support for ethtool's '-r' command. Restarting
N-WAY negotiation can be useful to activate newly changed EEE
settings etc.
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/cpsw.c

@@ -2261,6 +2261,18 @@ static int cpsw_set_eee(struct net_device *ndev, struct ethtool_eee *edata)
 		return -EOPNOTSUPP;
 }
 
+static int cpsw_nway_reset(struct net_device *ndev)
+{
+	struct cpsw_priv *priv = netdev_priv(ndev);
+	struct cpsw_common *cpsw = priv->cpsw;
+	int slave_no = cpsw_slave_index(cpsw, priv);
+
+	if (cpsw->slaves[slave_no].phy)
+		return genphy_restart_aneg(cpsw->slaves[slave_no].phy);
+	else
+		return -EOPNOTSUPP;
+}
+
 static const struct ethtool_ops cpsw_ethtool_ops = {
 	.get_drvinfo	= cpsw_get_drvinfo,
 	.get_msglevel	= cpsw_get_msglevel,
@@ -2286,6 +2298,7 @@ static const struct ethtool_ops cpsw_ethtool_ops = {
 	.set_link_ksettings	= cpsw_set_link_ksettings,
 	.get_eee	= cpsw_get_eee,
 	.set_eee	= cpsw_set_eee,
+	.nway_reset	= cpsw_nway_reset,
 };
 
 static void cpsw_slave_init(struct cpsw_slave *slave, struct cpsw_common *cpsw,