netdev: octeon_mgmt: Improve ethtool_ops.

Correctly show no link when the interface is down, and return
-EOPNOTSUPP for things that don't work.  This quiets the ethtool
program when run on down interfaces.

Signed-off-by: David Daney <david.daney@cavium.com>
Acked-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/octeon/octeon_mgmt.c

@@ -1379,7 +1379,7 @@ static int octeon_mgmt_get_settings(struct net_device *netdev,
 	if (p->phydev)
 		return phy_ethtool_gset(p->phydev, cmd);
 
-	return -EINVAL;
+	return -EOPNOTSUPP;
 }
 
 static int octeon_mgmt_set_settings(struct net_device *netdev,
@@ -1393,14 +1393,28 @@ static int octeon_mgmt_set_settings(struct net_device *netdev,
 	if (p->phydev)
 		return phy_ethtool_sset(p->phydev, cmd);
 
-	return -EINVAL;
+	return -EOPNOTSUPP;
+}
+
+static int octeon_mgmt_nway_reset(struct net_device *dev)
+{
+	struct octeon_mgmt *p = netdev_priv(dev);
+
+	if (!capable(CAP_NET_ADMIN))
+		return -EPERM;
+
+	if (p->phydev)
+		return phy_start_aneg(p->phydev);
+
+	return -EOPNOTSUPP;
 }
 
 static const struct ethtool_ops octeon_mgmt_ethtool_ops = {
 	.get_drvinfo = octeon_mgmt_get_drvinfo,
-	.get_link = ethtool_op_get_link,
 	.get_settings = octeon_mgmt_get_settings,
-	.set_settings = octeon_mgmt_set_settings
+	.set_settings = octeon_mgmt_set_settings,
+	.nway_reset = octeon_mgmt_nway_reset,
+	.get_link = ethtool_op_get_link,
 };
 
 static const struct net_device_ops octeon_mgmt_ops = {