net: phy: dp83867: Add lane swapping support in the DP83867 TI's PHY driver

This patch adds support for enabling or disabling the lane swapping (called
"port mirroring" in PHY's CFG4 register) feature of the DP83867 TI's PHY
device.

One use case is when bootstrap configuration enables this feature (because
of e.g. LED_0 wrong wiring) so then one needs to disable it in software
(at u-boot/Linux).

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/dp83867.c

@@ -32,6 +32,7 @@
 #define DP83867_CFG3		0x1e
 
 /* Extended Registers */
+#define DP83867_CFG4            0x0031
 #define DP83867_RGMIICTL	0x0032
 #define DP83867_RGMIIDCTL	0x0086
 #define DP83867_IO_MUX_CFG	0x0170
@@ -70,11 +71,21 @@
 #define DP83867_IO_MUX_CFG_IO_IMPEDANCE_MAX	0x0
 #define DP83867_IO_MUX_CFG_IO_IMPEDANCE_MIN	0x1f
 
+/* CFG4 bits */
+#define DP83867_CFG4_PORT_MIRROR_EN              BIT(0)
+
+enum {
+	DP83867_PORT_MIRROING_KEEP,
+	DP83867_PORT_MIRROING_EN,
+	DP83867_PORT_MIRROING_DIS,
+};
+
 struct dp83867_private {
 	int rx_id_delay;
 	int tx_id_delay;
 	int fifo_depth;
 	int io_impedance;
+	int port_mirroring;
 };
 
 static int dp83867_ack_interrupt(struct phy_device *phydev)
@@ -111,6 +122,24 @@ static int dp83867_config_intr(struct phy_device *phydev)
 	return phy_write(phydev, MII_DP83867_MICR, micr_status);
 }
 
+static int dp83867_config_port_mirroring(struct phy_device *phydev)
+{
+	struct dp83867_private *dp83867 =
+		(struct dp83867_private *)phydev->priv;
+	u16 val;
+
+	val = phy_read_mmd_indirect(phydev, DP83867_CFG4, DP83867_DEVADDR);
+
+	if (dp83867->port_mirroring == DP83867_PORT_MIRROING_EN)
+		val |= DP83867_CFG4_PORT_MIRROR_EN;
+	else
+		val &= ~DP83867_CFG4_PORT_MIRROR_EN;
+
+	phy_write_mmd_indirect(phydev, DP83867_CFG4, DP83867_DEVADDR, val);
+
+	return 0;
+}
+
 #ifdef CONFIG_OF_MDIO
 static int dp83867_of_init(struct phy_device *phydev)
 {
@@ -144,6 +173,12 @@ static int dp83867_of_init(struct phy_device *phydev)
 	     phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID))
 		return ret;
 
+	if (of_property_read_bool(of_node, "enet-phy-lane-swap"))
+		dp83867->port_mirroring = DP83867_PORT_MIRROING_EN;
+
+	if (of_property_read_bool(of_node, "enet-phy-lane-no-swap"))
+		dp83867->port_mirroring = DP83867_PORT_MIRROING_DIS;
+
 	return of_property_read_u32(of_node, "ti,fifo-depth",
 				   &dp83867->fifo_depth);
 }
@@ -228,6 +263,9 @@ static int dp83867_config_init(struct phy_device *phydev)
 		phy_write(phydev, DP83867_CFG3, val);
 	}
 
+	if (dp83867->port_mirroring != DP83867_PORT_MIRROING_KEEP)
+		dp83867_config_port_mirroring(phydev);
+
 	return 0;
 }