WSL2-Linux-Kernel/Documentation/devicetree/bindings/net/mdio-mux-mmioreg.txt

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Properties for an MDIO bus multiplexer controlled by a memory-mapped device
This is a special case of a MDIO bus multiplexer. A memory-mapped device,
like an FPGA, is used to control which child bus is connected. The mdio-mux
node must be a child of the memory-mapped device. The driver currently only
supports devices with eight-bit registers.
Required properties in addition to the generic multiplexer properties:
- compatible : string, must contain "mdio-mux-mmioreg"
- reg : integer, contains the offset of the register that controls the bus
multiplexer. The size field in the 'reg' property is the size of
register, and must therefore be 1.
- mux-mask : integer, contains an eight-bit mask that specifies which
bits in the register control the actual bus multiplexer. The
'reg' property of each child mdio-mux node must be constrained by
this mask.
Example:
The FPGA node defines a memory-mapped FPGA with a register space of 0x30 bytes.
For the "EMI2" MDIO bus, register 9 (BRDCFG1) controls the mux on that bus.
A bitmask of 0x6 means that bits 1 and 2 (bit 0 is lsb) are the bits on
BRDCFG1 that control the actual mux.
/* The FPGA node */
fpga: board-control@3,0 {
#address-cells = <1>;
#size-cells = <1>;
compatible = "fsl,p5020ds-fpga", "fsl,fpga-ngpixis";
reg = <3 0 0x30>;
ranges = <0 3 0 0x30>;
mdio-mux-emi2 {
compatible = "mdio-mux-mmioreg", "mdio-mux";
mdio-parent-bus = <&xmdio0>;
#address-cells = <1>;
#size-cells = <0>;
reg = <9 1>; // BRDCFG1
mux-mask = <0x6>; // EMI2
emi2_slot1: mdio@0 { // Slot 1 XAUI (FM2)
reg = <0>;
#address-cells = <1>;
#size-cells = <0>;
phy_xgmii_slot1: ethernet-phy@0 {
compatible = "ethernet-phy-ieee802.3-c45";
reg = <4>;
};
};
emi2_slot2: mdio@2 { // Slot 2 XAUI (FM1)
reg = <2>;
#address-cells = <1>;
#size-cells = <0>;
phy_xgmii_slot2: ethernet-phy@4 {
compatible = "ethernet-phy-ieee802.3-c45";
reg = <0>;
};
};
};
};
/* The parent MDIO bus. */
xmdio0: mdio@f1000 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "fsl,fman-xmdio";
reg = <0xf1000 0x1000>;
interrupts = <100 1 0 0>;
};