[PATCH 3/4] dt-bindings: mediatek: add doc for MediaTek MT7987/MT7988 2.5Gb ethernrt PHY

[Weijie Gao]

The MediaTek MT7987 and MT7988 platforms supports one built-in 2.5Gb
ethernet PHY through eth1 interface.

This patch add documentation for configuring these PHYs.

Signed-off-by: Sky Huang <SkyLake.Huang at mediatek.com>
Signed-off-by: Weijie Gao <weijie.gao at mediatek.com>
---
 .../net/phy/mediatek,mt798x-i2p5ge-phy.txt    | 60 +++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 doc/device-tree-bindings/net/phy/mediatek,mt798x-i2p5ge-phy.txt

diff --git a/doc/device-tree-bindings/net/phy/mediatek,mt798x-i2p5ge-phy.txt b/doc/device-tree-bindings/net/phy/mediatek,mt798x-i2p5ge-phy.txt
new file mode 100644
index 00000000000..ebac28d2d9a
--- /dev/null
+++ b/doc/device-tree-bindings/net/phy/mediatek,mt798x-i2p5ge-phy.txt
@@ -0,0 +1,60 @@
+MediaTek MT7987/MT7988 built-in 2.5Gb Ethernet PHY
+
+This document describes the device tree bindings for MediaTek MT7987/MT7988
+built-in 2.5Gb Ethernet PHY.
+
+Required properties:
+- reg: The phy address
+
+Optional properties:
+- pd-disable: Boolean. PD (Parallel detction) is enabled in this PHY, even
+  though this may cause duplex mismatch for devices supporting only 10M/half
+  or 100M/half. If you are concerned with duplex mismatch, use this option to
+  prevent this built-in PHY to link up with those devices.
+
+- gbe-min-ipg-11-bytes: Boolean. If present, enables 11-byte minimum
+  inter-packet gap for 1000Mbps link speed. When not present (by default),
+  the PHY uses optimized IPG settings for better performance. This option is
+  basically for those legacy 1G link partners which only accept higher IPG
+  transfer.
+
+- auto-downshift-disable: Boolean. If present, disables the hardware
+  auto-downshift feature. When not present (by default), the PHY will
+  automatically downshift link speed when link quality is poor.
+
+- pinctrl-names: Accepts "i2p5gbe-led" pinctrl for PHY status indicator
+
+Notes:
+- Firmware loading is required for proper operation. The driver expects
+  firmware files to be available through weak symbol functions provided by
+  boards.
+
+Examples:
+&eth1 {
+	status = "okay";
+	phy-mode = "xgmii";
+	phy-handle = <&phy15>;
+
+	phy15: ethernet-phy at 15 {
+		compatible = "ethernet-phy-ieee802.3-c45";
+		reg = <15>;
+		phy-mode = "xgmii";
+	};
+};
+
+&eth1 {
+	status = "okay";
+	pinctrl-names = "i2p5gbe-led";
+	pinctrl-0 = <&i2p5gbe_led0_pins>;
+	phy-mode = "xgmii";
+	phy-handle = <&phy15>;
+
+	phy15: ethernet-phy at 15 {
+		compatible = "ethernet-phy-ieee802.3-c45";
+		reg = <15>;
+		pd-disable;
+		gbe-min-ipg-11-bytes;
+		auto-downshift-disable;
+		phy-mode = "xgmii";
+	};
+};
-- 
2.34.1