net: dsa: mv88e6xxx: add cap for MGMT Enables bits

Some switches provide a Rsvd2CPU mechanism used to choose which of the
16 reserved multicast destination addresses matching 01:80:c2:00:00:0x
should be considered as MGMT and thus forwarded to the CPU port.

Other switches extend this mechanism to also configure as MGMT the
additional 16 reserved multicast addresses matching 01:80:c2:00:00:2x.

This mechanism is exposed via two registers in Global 2, and an Rsvd2CPU
enable bit in the management register.

Newer chip (such as 88E6390) has replaced these registers with a new
indirect MGMT mechanism in Global 1.

The patch adds two MV88E6XXX_FLAG_G2_MGMT_EN_{0,2}X flags to describe
the presence of these Global 2 registers. If 88E6390 support is added, a
MV88E6XXX_FLAG_G1_MGMT_CTRL flag will be needed to setup Rsvd2CPU.

Note: all switches still support in parallel the ATU Load operation with
an MGMT Entry State to forward such frames in a less convenient way.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index d18e5c8..cf98884 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -3196,25 +3196,40 @@
 
 static int mv88e6xxx_g2_setup(struct mv88e6xxx_chip *chip)
 {
+	u16 reg;
 	int err;
 	int i;
 
-	/* Send all frames with destination addresses matching
-	 * 01:80:c2:00:00:0x to the CPU port.
-	 */
-	err = _mv88e6xxx_reg_write(chip, REG_GLOBAL2, GLOBAL2_MGMT_EN_0X,
-				   0xffff);
-	if (err)
-		return err;
+	if (mv88e6xxx_has(chip, MV88E6XXX_FLAG_G2_MGMT_EN_2X)) {
+		/* Consider the frames with reserved multicast destination
+		 * addresses matching 01:80:c2:00:00:2x as MGMT.
+		 */
+		err = mv88e6xxx_write(chip, REG_GLOBAL2, GLOBAL2_MGMT_EN_2X,
+				      0xffff);
+		if (err)
+			return err;
+	}
+
+	if (mv88e6xxx_has(chip, MV88E6XXX_FLAG_G2_MGMT_EN_0X)) {
+		/* Consider the frames with reserved multicast destination
+		 * addresses matching 01:80:c2:00:00:0x as MGMT.
+		 */
+		err = mv88e6xxx_write(chip, REG_GLOBAL2, GLOBAL2_MGMT_EN_0X,
+				      0xffff);
+		if (err)
+			return err;
+	}
 
 	/* Ignore removed tag data on doubly tagged packets, disable
 	 * flow control messages, force flow control priority to the
 	 * highest, and send all special multicast frames to the CPU
 	 * port at the highest priority.
 	 */
-	err = _mv88e6xxx_reg_write(chip, REG_GLOBAL2, GLOBAL2_SWITCH_MGMT,
-				   0x7 | GLOBAL2_SWITCH_MGMT_RSVD2CPU | 0x70 |
-				   GLOBAL2_SWITCH_MGMT_FORCE_FLOW_CTRL_PRI);
+	reg = GLOBAL2_SWITCH_MGMT_FORCE_FLOW_CTRL_PRI | (0x7 << 4);
+	if (mv88e6xxx_has(chip, MV88E6XXX_FLAG_G2_MGMT_EN_0X) ||
+	    mv88e6xxx_has(chip, MV88E6XXX_FLAG_G2_MGMT_EN_2X))
+		reg |= GLOBAL2_SWITCH_MGMT_RSVD2CPU | 0x7;
+	err = mv88e6xxx_write(chip, REG_GLOBAL2, GLOBAL2_SWITCH_MGMT, reg);
 	if (err)
 		return err;
 
@@ -3231,14 +3246,6 @@
 	if (mv88e6xxx_6352_family(chip) || mv88e6xxx_6351_family(chip) ||
 	    mv88e6xxx_6165_family(chip) || mv88e6xxx_6097_family(chip) ||
 	    mv88e6xxx_6320_family(chip)) {
-		/* Send all frames with destination addresses matching
-		 * 01:80:c2:00:00:2x to the CPU port.
-		 */
-		err = _mv88e6xxx_reg_write(chip, REG_GLOBAL2,
-					   GLOBAL2_MGMT_EN_2X, 0xffff);
-		if (err)
-			return err;
-
 		/* Initialise cross-chip port VLAN table to reset
 		 * defaults.
 		 */