net: dsa: add master helper to look up slaves

The DSA tagging code does not need to know about the DSA architecture,
it only needs to return the slave device corresponding to the source
port index (and eventually the source device index for cascade-capable
switches) parsed from the frame received on the master device.

For this purpose, provide an inline dsa_master_get_slave helper which
validates the device and port indexes and look up the slave device.

This makes the tagging rcv functions more concise and robust, and also
makes dsa_get_cpu_port obsolete.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 5 deletions

diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index eccc62776283..d429505dc4e7 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -113,6 +113,25 @@ int dsa_legacy_fdb_del(struct ndmsg *ndm, struct nlattr *tb[],
 int dsa_master_ethtool_setup(struct net_device *dev);
 void dsa_master_ethtool_restore(struct net_device *dev);
 
+static inline struct net_device *dsa_master_get_slave(struct net_device *dev,
+						      int device, int port)
+{
+	struct dsa_switch_tree *dst = dev->dsa_ptr;
+	struct dsa_switch *ds;
+
+	if (device < 0 || device >= DSA_MAX_SWITCHES)
+		return NULL;
+
+	ds = dst->ds[device];
+	if (!ds)
+		return NULL;
+
+	if (port < 0 || port >= ds->num_ports)
+		return NULL;
+
+	return ds->ports[port].netdev;
+}
+
 /* port.c */
 int dsa_port_set_state(struct dsa_port *dp, u8 state,
 		       struct switchdev_trans *trans);
@@ -182,9 +201,4 @@ static inline struct net_device *dsa_master_netdev(struct dsa_slave_priv *p)
 	return p->dp->cpu_dp->netdev;
 }
 
-static inline struct dsa_port *dsa_get_cpu_port(struct dsa_switch_tree *dst)
-{
-	return dst->cpu_dp;
-}
-
 #endif