net: dsa: mv88e6xxx: add phylink support

Add rudimentary phylink support to mv88e6xxx.

TODO:
- needs to call phylink_mac_change() when the port link comes up/goes down.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/port.c

@@ -388,6 +388,19 @@ int mv88e6390x_port_set_cmode(struct mv88e6xxx_chip *chip, int port,
 	return 0;
 }
 
+/* mv88e6185 only has 3 bits for CMODE */
+static int mv88e6185_port_get_cmode(struct mv88e6xxx_chip *chip, int port)
+{
+	int err;
+	u16 reg;
+
+	err = mv88e6xxx_port_read(chip, port, MV88E6XXX_PORT_STS, &reg);
+	if (err)
+		return err;
+
+	return reg & MV88E6185_PORT_STS_CMODE_MASK;
+}
+
 int mv88e6xxx_port_get_cmode(struct mv88e6xxx_chip *chip, int port, u8 *cmode)
 {
 	int err;
@@ -402,7 +415,7 @@ int mv88e6xxx_port_get_cmode(struct mv88e6xxx_chip *chip, int port, u8 *cmode)
 	return 0;
 }
 
-int mv88e6xxx_port_link_state(struct mv88e6xxx_chip *chip, int port,
+int mv88e6352_port_link_state(struct mv88e6xxx_chip *chip, int port,
 			      struct phylink_link_state *state)
 {
 	int err;
@@ -423,7 +436,7 @@ int mv88e6xxx_port_link_state(struct mv88e6xxx_chip *chip, int port,
 		state->speed = SPEED_1000;
 		break;
 	case MV88E6XXX_PORT_STS_SPEED_10000:
-		if ((reg &MV88E6XXX_PORT_STS_CMODE_MASK) ==
+		if ((reg & MV88E6XXX_PORT_STS_CMODE_MASK) ==
 		    MV88E6XXX_PORT_STS_CMODE_2500BASEX)
 			state->speed = SPEED_2500;
 		else
@@ -440,6 +453,45 @@ int mv88e6xxx_port_link_state(struct mv88e6xxx_chip *chip, int port,
 	return 0;
 }
 
+int mv88e6185_port_link_state(struct mv88e6xxx_chip *chip, int port,
+			      struct phylink_link_state *state)
+{
+	if (state->interface == PHY_INTERFACE_MODE_1000BASEX) {
+		int cmode = mv88e6185_port_get_cmode(chip, port);
+
+		if (cmode < 0)
+			return cmode;
+
+		/* When a port is in "Cross-chip serdes" mode, it uses
+		 * 1000Base-X full duplex mode, but there is no automatic
+		 * link detection. Use the sync OK status for link (as it
+		 * would do for 1000Base-X mode.)
+		 */
+		if (cmode == MV88E6185_PORT_STS_CMODE_SERDES) {
+			u16 mac;
+			int err;
+
+			err = mv88e6xxx_port_read(chip, port,
+						  MV88E6XXX_PORT_MAC_CTL, &mac);
+			if (err)
+				return err;
+
+			state->link = !!(mac & MV88E6185_PORT_MAC_CTL_SYNC_OK);
+			state->an_enabled = 1;
+			state->an_complete =
+				!!(mac & MV88E6185_PORT_MAC_CTL_AN_DONE);
+			state->duplex =
+				state->link ? DUPLEX_FULL : DUPLEX_UNKNOWN;
+			state->speed =
+				state->link ? SPEED_1000 : SPEED_UNKNOWN;
+
+			return 0;
+		}
+	}
+
+	return mv88e6352_port_link_state(chip, port, state);
+}
+
 /* Offset 0x02: Jamming Control
  *
  * Do not limit the period of time that this port can be paused for by