dsa: mv88e6xxx: Set the RGMII delay based on phy interface

Some Marvell switches allow the RGMII Rx and Tx clock to be delayed
when the port is using RGMII. Have the adjust_link function look at
the phy interface type and enable this delay as requested.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx.c

@@ -612,6 +612,16 @@ void mv88e6xxx_adjust_link(struct dsa_switch *ds, int port,
 	if (phydev->duplex == DUPLEX_FULL)
 		reg |= PORT_PCS_CTRL_DUPLEX_FULL;
 
+	if ((mv88e6xxx_6352_family(ds) || mv88e6xxx_6351_family(ds)) &&
+	    (port >= ps->num_ports - 2)) {
+		if (phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID)
+			reg |= PORT_PCS_CTRL_RGMII_DELAY_RXCLK;
+		if (phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID)
+			reg |= PORT_PCS_CTRL_RGMII_DELAY_TXCLK;
+		if (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID)
+			reg |= (PORT_PCS_CTRL_RGMII_DELAY_RXCLK |
+				PORT_PCS_CTRL_RGMII_DELAY_TXCLK);
+	}
 	_mv88e6xxx_reg_write(ds, REG_PORT(port), PORT_PCS_CTRL, reg);
 
 out:

drivers/net/dsa/mv88e6xxx.h

@@ -46,6 +46,8 @@
 #define PORT_STATUS_TX_PAUSED	BIT(5)
 #define PORT_STATUS_FLOW_CTRL	BIT(4)
 #define PORT_PCS_CTRL		0x01
+#define PORT_PCS_CTRL_RGMII_DELAY_RXCLK	BIT(15)
+#define PORT_PCS_CTRL_RGMII_DELAY_TXCLK	BIT(14)
 #define PORT_PCS_CTRL_FC		BIT(7)
 #define PORT_PCS_CTRL_FORCE_FC		BIT(6)
 #define PORT_PCS_CTRL_LINK_UP		BIT(5)