net: dsa: mv88e6xxx: Implement the 6390 external MDIO bus

With all the infrastructure in place, implement access to the external
MDIO bus on the 6390 family.
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/global2.c

@@ -506,8 +506,12 @@ int mv88e6xxx_g2_smi_phy_read(struct mv88e6xxx_chip *chip,
 			      int addr, int reg, u16 *val)
 {
 	u16 cmd = GLOBAL2_SMI_PHY_CMD_OP_22_READ_DATA | (addr << 5) | reg;
+	struct mv88e6xxx_mdio_bus *mdio_bus = bus->priv;
 	int err;
 
+	if (mdio_bus->external)
+		cmd |= GLOBAL2_SMI_PHY_CMD_EXTERNAL;
+
 	err = mv88e6xxx_g2_smi_phy_wait(chip);
 	if (err)
 		return err;
@@ -524,8 +528,12 @@ int mv88e6xxx_g2_smi_phy_write(struct mv88e6xxx_chip *chip,
 			       int addr, int reg, u16 val)
 {
 	u16 cmd = GLOBAL2_SMI_PHY_CMD_OP_22_WRITE_DATA | (addr << 5) | reg;
+	struct mv88e6xxx_mdio_bus *mdio_bus = bus->priv;
 	int err;
 
+	if (mdio_bus->external)
+		cmd |= GLOBAL2_SMI_PHY_CMD_EXTERNAL;
+
 	err = mv88e6xxx_g2_smi_phy_wait(chip);
 	if (err)
 		return err;

drivers/net/dsa/mv88e6xxx/mv88e6xxx.h

@@ -387,6 +387,7 @@
 #define GLOBAL2_PTP_AVB_DATA	0x17
 #define GLOBAL2_SMI_PHY_CMD			0x18
 #define GLOBAL2_SMI_PHY_CMD_BUSY		BIT(15)
+#define GLOBAL2_SMI_PHY_CMD_EXTERNAL		BIT(13)
 #define GLOBAL2_SMI_PHY_CMD_MODE_22		BIT(12)
 #define GLOBAL2_SMI_PHY_CMD_OP_22_WRITE_DATA	((0x1 << 10) | \
 						 GLOBAL2_SMI_PHY_CMD_MODE_22 | \