nfp: add support restart of link auto-negotiation

Add support restart of link auto-negotiation.
This may be initiated using:

  # ethtool -r <intf>
Signed-off-by: Fei Qin <fei.qin@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/netronome/nfp/nfp_net_ethtool.c

@@ -228,6 +228,37 @@ nfp_net_get_drvinfo(struct net_device *netdev, struct ethtool_drvinfo *drvinfo)
 	nfp_get_drvinfo(nn->app, nn->pdev, vnic_version, drvinfo);
 }
 
+static int
+nfp_net_nway_reset(struct net_device *netdev)
+{
+	struct nfp_eth_table_port *eth_port;
+	struct nfp_port *port;
+	int err;
+
+	port = nfp_port_from_netdev(netdev);
+	eth_port = nfp_port_get_eth_port(port);
+	if (!eth_port)
+		return -EOPNOTSUPP;
+
+	if (!netif_running(netdev))
+		return 0;
+
+	err = nfp_eth_set_configured(port->app->cpp, eth_port->index, false);
+	if (err) {
+		netdev_info(netdev, "Link down failed: %d\n", err);
+		return err;
+	}
+
+	err = nfp_eth_set_configured(port->app->cpp, eth_port->index, true);
+	if (err) {
+		netdev_info(netdev, "Link up failed: %d\n", err);
+		return err;
+	}
+
+	netdev_info(netdev, "Link reset succeeded\n");
+	return 0;
+}
+
 static void
 nfp_app_get_drvinfo(struct net_device *netdev, struct ethtool_drvinfo *drvinfo)
 {
@@ -1841,6 +1872,7 @@ static const struct ethtool_ops nfp_net_ethtool_ops = {
 				     ETHTOOL_COALESCE_MAX_FRAMES |
 				     ETHTOOL_COALESCE_USE_ADAPTIVE,
 	.get_drvinfo		= nfp_net_get_drvinfo,
+	.nway_reset             = nfp_net_nway_reset,
 	.get_link		= ethtool_op_get_link,
 	.get_ringparam		= nfp_net_get_ringparam,
 	.set_ringparam		= nfp_net_set_ringparam,
@@ -1878,6 +1910,7 @@ static const struct ethtool_ops nfp_net_ethtool_ops = {
 
 const struct ethtool_ops nfp_port_ethtool_ops = {
 	.get_drvinfo		= nfp_app_get_drvinfo,
+	.nway_reset             = nfp_net_nway_reset,
 	.get_link		= ethtool_op_get_link,
 	.get_strings		= nfp_port_get_strings,
 	.get_ethtool_stats	= nfp_port_get_stats,