net: dsa: mv88e6xxx: Support policy entries in the VTU

A VTU entry with policy enabled is used in combination with a port's
VTU policy setting to override normal switching behavior for frames
assigned to the entry's VID.

A typical example is to Treat all frames in a particular VLAN as
control traffic, and trap them to the CPU. In which case the relevant
user port's VTU policy would be set to TRAP.
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/chip.h

@@ -179,6 +179,7 @@ struct mv88e6xxx_vtu_entry {
 	u16	fid;
 	u8	sid;
 	bool	valid;
+	bool	policy;
 	u8	member[DSA_MAX_PORTS];
 	u8	state[DSA_MAX_PORTS];
 };

drivers/net/dsa/mv88e6xxx/global1.h

@@ -46,6 +46,7 @@
 
 /* Offset 0x02: VTU FID Register */
 #define MV88E6352_G1_VTU_FID		0x02
+#define MV88E6352_G1_VTU_FID_VID_POLICY	0x1000
 #define MV88E6352_G1_VTU_FID_MASK	0x0fff
 
 /* Offset 0x03: VTU SID Register */

drivers/net/dsa/mv88e6xxx/global1_vtu.c

@@ -27,7 +27,7 @@ static int mv88e6xxx_g1_vtu_fid_read(struct mv88e6xxx_chip *chip,
 		return err;
 
 	entry->fid = val & MV88E6352_G1_VTU_FID_MASK;
-
+	entry->policy = !!(val & MV88E6352_G1_VTU_FID_VID_POLICY);
 	return 0;
 }
 
@@ -36,6 +36,9 @@ static int mv88e6xxx_g1_vtu_fid_write(struct mv88e6xxx_chip *chip,
 {
 	u16 val = entry->fid & MV88E6352_G1_VTU_FID_MASK;
 
+	if (entry->policy)
+		val |= MV88E6352_G1_VTU_FID_VID_POLICY;
+
 	return mv88e6xxx_g1_write(chip, MV88E6352_G1_VTU_FID, val);
 }