net: dsa: retain a per-port device_node pointer

We will later use the per-port device_node pointer to fetch a bunch of
port-specific properties.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -41,6 +41,7 @@ struct dsa_chip_data {
 	 * or any other string to indicate this is a physical port.
 	 */
 	char		*port_names[DSA_MAX_PORTS];
+	struct device_node *port_dn[DSA_MAX_PORTS];
 
 	/*
 	 * An array (with nr_chips elements) of which element [a]

net/dsa/dsa.c

@@ -432,6 +432,8 @@ static int dsa_of_probe(struct platform_device *pdev)
 			if (!port_name)
 				continue;
 
+			cd->port_dn[port_index] = port;
+
 			cd->port_names[port_index] = kstrdup(port_name,
 					GFP_KERNEL);
 			if (!cd->port_names[port_index]) {

net/dsa/slave.c

@@ -354,6 +354,7 @@ dsa_slave_create(struct dsa_switch *ds, struct device *parent,
 	}
 
 	SET_NETDEV_DEV(slave_dev, parent);
+	slave_dev->dev.of_node = ds->pd->port_dn[port];
 	slave_dev->vlan_features = master->vlan_features;
 
 	p = netdev_priv(slave_dev);