net: dsa: setup and teardown master device

Add DSA helpers to setup and teardown a master net device wired to its
CPU port. This centralizes the dsa_ptr assignment.

This also makes the master ethtool helpers static at the same time.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dsa/legacy.c b/net/dsa/legacy.c
index 0511fe2..4863e3e 100644
--- a/net/dsa/legacy.c
+++ b/net/dsa/legacy.c
@@ -593,15 +593,7 @@
 	if (!configured)
 		return -EPROBE_DEFER;
 
-	/*
-	 * If we use a tagging format that doesn't have an ethertype
-	 * field, make sure that all packets from this point on get
-	 * sent to the tag format's receive function.
-	 */
-	wmb();
-	dev->dsa_ptr = dst->cpu_dp;
-
-	return dsa_master_ethtool_setup(dst->cpu_dp->master);
+	return dsa_master_setup(dst->cpu_dp->master, dst->cpu_dp);
 }
 
 static int dsa_probe(struct platform_device *pdev)
@@ -666,15 +658,7 @@
 {
 	int i;
 
-	dsa_master_ethtool_restore(dst->cpu_dp->master);
-
-	dst->cpu_dp->master->dsa_ptr = NULL;
-
-	/* If we used a tagging format that doesn't have an ethertype
-	 * field, make sure that all packets from this point get sent
-	 * without the tag and go through the regular receive path.
-	 */
-	wmb();
+	dsa_master_teardown(dst->cpu_dp->master);
 
 	for (i = 0; i < dst->pd->nr_chips; i++) {
 		struct dsa_switch *ds = dst->ds[i];