net: phy: ti: 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).

Based on commit fc6d39c39581 ("net: phy: dp83867: Add lane swapping
support in the DP83867 TI's PHY driver") of mainline linux kernel.

Signed-off-by: Janine Hagemann <j.hagemann@phytec.de>
Acked-by: Lukasz Majewski <lukma@denx.de>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

doc/device-tree-bindings/net/ti,dp83867.txt

@@ -8,6 +8,10 @@ Required properties:
 		for applicable values
 	- ti,fifo-depth - Transmitt FIFO depth- see dt-bindings/net/ti-dp83867.h
 		for applicable values
+	- enet-phy-lane-swap - Indicates that PHY will swap the TX/RX lanes to
+		compensate for the board being designed with the lanes swapped.
+	- enet-phy-no-lane-swap - Indicates that PHY will disable swap of the
+		TX/RX lanes.
 
 Default child nodes are standard Ethernet PHY device
 nodes as described in doc/devicetree/bindings/net/ethernet.txt
@@ -19,6 +23,7 @@ Example:
 		ti,rx-internal-delay = <DP83867_RGMIIDCTL_2_25_NS>;
 		ti,tx-internal-delay = <DP83867_RGMIIDCTL_2_75_NS>;
 		ti,fifo-depth = <DP83867_PHYCR_FIFO_DEPTH_4_B_NIB>;
+		enet-phy-lane-no-swap;
 	};
 
 Datasheet can be found:

drivers/net/phy/ti.c

@@ -89,12 +89,22 @@
 #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_MIRRORING_KEEP,
+	DP83867_PORT_MIRRORING_EN,
+	DP83867_PORT_MIRRORING_DIS,
+};
+
 struct dp83867_private {
 	int rx_id_delay;
 	int tx_id_delay;
 	int fifo_depth;
 	int io_impedance;
 	bool rxctrl_strap_quirk;
+	int port_mirroring;
 };
 
 /**
@@ -163,6 +173,26 @@ void phy_write_mmd_indirect(struct phy_device *phydev, int prtad,
 	phy_write(phydev, addr, MII_MMD_DATA, data);
 }
 
+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,
+				    phydev->addr);
+
+	if (dp83867->port_mirroring == DP83867_PORT_MIRRORING_EN)
+		val |= DP83867_CFG4_PORT_MIRROR_EN;
+	else
+		val &= ~DP83867_CFG4_PORT_MIRROR_EN;
+
+	phy_write_mmd_indirect(phydev, DP83867_CFG4, DP83867_DEVADDR,
+			       phydev->addr, val);
+
+	return 0;
+}
+
 #if defined(CONFIG_DM_ETH)
 /**
  * dp83867_data_init - Convenience function for setting PHY specific data
@@ -197,6 +227,12 @@ static int dp83867_of_init(struct phy_device *phydev)
 
 	dp83867->fifo_depth = ofnode_read_u32_default(node, "ti,fifo-depth",
 						      -1);
+	if (ofnode_read_bool(node, "enet-phy-lane-swap"))
+		dp83867->port_mirroring = DP83867_PORT_MIRRORING_EN;
+
+	if (ofnode_read_bool(node, "enet-phy-lane-no-swap"))
+		dp83867->port_mirroring = DP83867_PORT_MIRRORING_DIS;
+
 
 	return 0;
 }
@@ -315,6 +351,9 @@ static int dp83867_config(struct phy_device *phydev)
 		}
 	}
 
+	if (dp83867->port_mirroring != DP83867_PORT_MIRRORING_KEEP)
+		dp83867_config_port_mirroring(phydev);
+
 	genphy_config_aneg(phydev);
 	return 0;