net: dsa: Associate slave network device with CPU port

In preparation for supporting multiple CPU ports with DSA, have the
dsa_port structure know which CPU it is associated with. This will be
important in order to make sure the correct CPU is used for transmission
of the frames. If not for functional reasons, for performance (e.g: load
balancing) and forwarding decisions.
Reviewed-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -171,6 +171,7 @@ struct dsa_port {
 	struct dsa_switch	*ds;
 	unsigned int		index;
 	const char		*name;
+	struct dsa_port		*cpu_dp;
 	struct net_device	*netdev;
 	struct device_node	*dn;
 	unsigned int		ageing_time;

net/dsa/dsa2.c

@@ -490,6 +490,8 @@ static int dsa_cpu_parse(struct dsa_port *port, u32 index,
 	enum dsa_tag_protocol tag_protocol;
 	struct net_device *ethernet_dev;
 	struct device_node *ethernet;
+	struct dsa_port *p;
+	unsigned int i;
 
 	if (port->dn) {
 		ethernet = of_parse_phandle(port->dn, "ethernet", 0);
@@ -507,6 +509,15 @@ static int dsa_cpu_parse(struct dsa_port *port, u32 index,
 	if (!dst->cpu_dp) {
 		dst->cpu_dp = port;
 		dst->cpu_dp->netdev = ethernet_dev;
+
+		for (i = 0; i < ds->num_ports; i++) {
+			p = &ds->ports[i];
+			if (!dsa_port_is_valid(p) ||
+			    i == index)
+				continue;
+
+			p->cpu_dp = port;
+		}
 	}
 
 	tag_protocol = ds->ops->get_tag_protocol(ds);

net/dsa/dsa_priv.h

@@ -185,7 +185,7 @@ extern const struct dsa_device_ops trailer_netdev_ops;
 
 static inline struct net_device *dsa_master_netdev(struct dsa_slave_priv *p)
 {
-	return p->dp->ds->dst->cpu_dp->netdev;
+	return p->dp->cpu_dp->netdev;
 }
 
 #endif

net/dsa/legacy.c

@@ -129,6 +129,7 @@ static int dsa_switch_setup_one(struct dsa_switch *ds, struct device *parent)
 			ds->dsa_port_mask |= 1 << i;
 		} else {
 			ds->enabled_port_mask |= 1 << i;
+			ds->ports[i].cpu_dp = dst->cpu_dp;
 		}
 		valid_name_found = true;
 	}

net/dsa/slave.c

@@ -1140,9 +1140,11 @@ int dsa_slave_create(struct dsa_switch *ds, struct device *parent,
 	struct net_device *master;
 	struct net_device *slave_dev;
 	struct dsa_slave_priv *p;
+	struct dsa_port *cpu_dp;
 	int ret;
 
-	master = ds->dst->cpu_dp->netdev;
+	cpu_dp = ds->dst->cpu_dp;
+	master = cpu_dp->netdev;
 
 	slave_dev = alloc_netdev(sizeof(struct dsa_slave_priv), name,
 				 NET_NAME_UNKNOWN, ether_setup);