net: dsa: Implement ndo_get_phys_port_name()

Return the physical port number of a DSA created network device using
ndo_get_phys_port_name().
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/slave.c

@@ -990,6 +990,15 @@ static int dsa_slave_get_phys_port_id(struct net_device *dev,
 
 	ppid->id_len = sizeof(p->port);
 	memcpy(ppid->id, &p->port, ppid->id_len);
+}
+
+static int dsa_slave_get_phys_port_name(struct net_device *dev,
+					char *name, size_t len)
+{
+	struct dsa_slave_priv *p = netdev_priv(dev);
+
+	if (snprintf(name, len, "p%d", p->port) >= len)
+		return -EINVAL;
 
 	return 0;
 }
@@ -1042,6 +1051,7 @@ static const struct net_device_ops dsa_slave_netdev_ops = {
 	.ndo_bridge_setlink	= switchdev_port_bridge_setlink,
 	.ndo_bridge_dellink	= switchdev_port_bridge_dellink,
 	.ndo_get_phys_port_id	= dsa_slave_get_phys_port_id,
+	.ndo_get_phys_port_name	= dsa_slave_get_phys_port_name,
 };
 
 static const struct switchdev_ops dsa_slave_switchdev_ops = {