net: mscc: ocelot: add a "valid" boolean to struct ocelot_vlan

Currently we are checking in some places whether the port has a native
VLAN on egress or not, by comparing the ocelot_port->vid value with zero.

That works, because VID 0 can never be a native VLAN configured by the
bridge, but now we want to make similar checks for the pvid. That won't
work, because there are cases when we do have the pvid set to 0 (not by
the bridge, by ourselves, but still.. it's confusing). And we can't
encode a negative value into an u16, so add a bool to the structure.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mscc/ocelot.c

@@ -153,22 +153,22 @@ static int ocelot_port_set_native_vlan(struct ocelot *ocelot, int port,
 	struct ocelot_port *ocelot_port = ocelot->ports[port];
 	u32 val = 0;
 
-	if (ocelot_port->native_vlan.vid != native_vlan.vid) {
-		/* Always permit deleting the native VLAN (vid = 0) */
-		if (ocelot_port->native_vlan.vid && native_vlan.vid) {
-			dev_err(ocelot->dev,
-				"Port already has a native VLAN: %d\n",
-				ocelot_port->native_vlan.vid);
-			return -EBUSY;
-		}
-		ocelot_port->native_vlan = native_vlan;
+	/* Deny changing the native VLAN, but always permit deleting it */
+	if (ocelot_port->native_vlan.vid != native_vlan.vid &&
+	    ocelot_port->native_vlan.valid && native_vlan.valid) {
+		dev_err(ocelot->dev,
+			"Port already has a native VLAN: %d\n",
+			ocelot_port->native_vlan.vid);
+		return -EBUSY;
 	}
 
+	ocelot_port->native_vlan = native_vlan;
+
 	ocelot_rmw_gix(ocelot, REW_PORT_VLAN_CFG_PORT_VID(native_vlan.vid),
 		       REW_PORT_VLAN_CFG_PORT_VID_M,
 		       REW_PORT_VLAN_CFG, port);
 
-	if (ocelot_port->vlan_aware && !ocelot_port->native_vlan.vid)
+	if (ocelot_port->vlan_aware && !ocelot_port->native_vlan.valid)
 		/* If port is vlan-aware and tagged, drop untagged and priority
 		 * tagged frames.
 		 */
@@ -182,7 +182,7 @@ static int ocelot_port_set_native_vlan(struct ocelot *ocelot, int port,
 		       ANA_PORT_DROP_CFG, port);
 
 	if (ocelot_port->vlan_aware) {
-		if (ocelot_port->native_vlan.vid)
+		if (native_vlan.valid)
 			/* Tag all frames except when VID == DEFAULT_VLAN */
 			val = REW_TAG_CFG_TAG_CFG(1);
 		else
@@ -273,6 +273,7 @@ int ocelot_vlan_add(struct ocelot *ocelot, int port, u16 vid, bool pvid,
 		struct ocelot_vlan pvid_vlan;
 
 		pvid_vlan.vid = vid;
+		pvid_vlan.valid = true;
 		ocelot_port_set_pvid(ocelot, port, pvid_vlan);
 	}
 
@@ -281,6 +282,7 @@ int ocelot_vlan_add(struct ocelot *ocelot, int port, u16 vid, bool pvid,
 		struct ocelot_vlan native_vlan;
 
 		native_vlan.vid = vid;
+		native_vlan.valid = true;
 		ret = ocelot_port_set_native_vlan(ocelot, port, native_vlan);
 		if (ret)
 			return ret;
@@ -303,9 +305,8 @@ int ocelot_vlan_del(struct ocelot *ocelot, int port, u16 vid)
 
 	/* Egress */
 	if (ocelot_port->native_vlan.vid == vid) {
-		struct ocelot_vlan native_vlan;
+		struct ocelot_vlan native_vlan = {0};
 
-		native_vlan.vid = 0;
 		ocelot_port_set_native_vlan(ocelot, port, native_vlan);
 	}
 

include/soc/mscc/ocelot.h

@@ -572,6 +572,7 @@ struct ocelot_vcap_block {
 };
 
 struct ocelot_vlan {
+	bool valid;
 	u16 vid;
 };