net: dsa: let switches specify their tagging protocol

In order to support the new DSA device driver model, a dsa_switch should
be able to advertise the type of tagging protocol supported by the
underlying switch device. This also removes constraints on how tagging
can be stacked to each other.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -127,6 +127,11 @@ struct dsa_switch {
 	struct dsa_switch_tree	*dst;
 	int			index;
 
+	/*
+	 * Tagging protocol understood by this switch
+	 */
+	enum dsa_tag_protocol	tag_protocol;
+
 	/*
 	 * Configuration data for this switch.
 	 */

net/dsa/dsa.c

@@ -227,7 +227,7 @@ static int dsa_switch_setup_one(struct dsa_switch *ds, struct device *parent)
 	 * switch.
 	 */
 	if (dst->cpu_switch == index) {
-		switch (drv->tag_protocol) {
+		switch (ds->tag_protocol) {
 #ifdef CONFIG_NET_DSA_TAG_DSA
 		case DSA_TAG_PROTO_DSA:
 			dst->rcv = dsa_netdev_ops.rcv;
@@ -255,7 +255,7 @@ static int dsa_switch_setup_one(struct dsa_switch *ds, struct device *parent)
 			goto out;
 		}
 
-		dst->tag_protocol = drv->tag_protocol;
+		dst->tag_protocol = ds->tag_protocol;
 	}
 
 	/*
@@ -364,6 +364,7 @@ dsa_switch_setup(struct dsa_switch_tree *dst, int index,
 	ds->index = index;
 	ds->pd = pd;
 	ds->drv = drv;
+	ds->tag_protocol = drv->tag_protocol;
 	ds->master_dev = host_dev;
 
 	ret = dsa_switch_setup_one(ds, parent);