net: dsa: read mac address from DT for slave device

Before creating a slave netdevice, get the mac address from DTS and
apply in case it is valid.

Signed-off-by: Xiaofei Shen <xiaofeis@codeaurora.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Xiaofei Shen

include/net/dsa.h

@@ -140,6 +140,7 @@ struct dsa_port {
 	unsigned int		index;
 	const char		*name;
 	const struct dsa_port	*cpu_dp;
+	const char		*mac;
 	struct device_node	*dn;
 	unsigned int		ageing_time;
 	u8			stp_state;

net/dsa/dsa2.c

@@ -266,6 +266,7 @@ static int dsa_port_setup(struct dsa_port *dp)
 		return 0;
 
 	memset(&dp->devlink_port, 0, sizeof(dp->devlink_port));
+	dp->mac = of_get_mac_address(dp->dn);
 
 	switch (dp->type) {
 	case DSA_PORT_TYPE_CPU:

net/dsa/slave.c

@@ -1393,7 +1393,10 @@ int dsa_slave_create(struct dsa_port *port)
 				NETIF_F_HW_VLAN_CTAG_FILTER;
 	slave_dev->hw_features |= NETIF_F_HW_TC;
 	slave_dev->ethtool_ops = &dsa_slave_ethtool_ops;
-	eth_hw_addr_inherit(slave_dev, master);
+	if (port->mac && is_valid_ether_addr(port->mac))
+		ether_addr_copy(slave_dev->dev_addr, port->mac);
+	else
+		eth_hw_addr_inherit(slave_dev, master);
 	slave_dev->priv_flags |= IFF_NO_QUEUE;
 	slave_dev->netdev_ops = &dsa_slave_netdev_ops;
 	slave_dev->min_mtu = 0;