20af5adf22
Adds a short bindings document describing the expected structure of a MDIO MUX dts node. This is based on Linux binding and the example is in fact copied from there. Signed-off-by: Alex Marginean <alexm.osslist@gmail.com> Acked-by: Joe Hershberger <joe.hershberger@ni.com> Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
139 lines
4.1 KiB
Plaintext
139 lines
4.1 KiB
Plaintext
The expected structure of an MDIO MUX device tree node is described here. This
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is heavily based on current Linux specification.
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One notable difference to Linux is that mdio-parent-bus is currently required
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by U-Boot, not optional as is in Linux. Current U-Boot MDIO MUX udevice class
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implementation does not have specific support for MDIOs with an integrated MUX,
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the property should be made optional if such support is added.
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The MDIO buses downstream of the MUX should be described in the device tree as
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child nodes as indicated below.
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Required properties:
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mdio-parent-bus = a phandle to the MDIO bus used to perform actual I/O. This is
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typically a real MDIO device, unless there are cascaded MUXes.
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#address-cells = <1>, each MDIO group is identified by one 32b value.
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#size-cells = <0>
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Other properties:
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The properties described here are sufficient for MDIO MUX DM class code, but
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MUX drivers may define additional properties, either required or optional.
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Required properties in child nodes:
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reg = value to be configured on the MUX to select the respective downstream
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MDIO.
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Child nodes should normally contain PHY nodes, referenced by phandle from
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ethernet nodes of the eth interfaces using these PHYs.
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Example structure, extracted from Linux bindings document:
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/* The parent MDIO bus. */
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smi1: mdio@1180000001900 {
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compatible = "cavium,octeon-3860-mdio";
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#address-cells = <1>;
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#size-cells = <0>;
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reg = <0x11800 0x00001900 0x0 0x40>;
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};
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/*
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* An NXP sn74cbtlv3253 dual 1-of-4 switch controlled by a
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* pair of GPIO lines. Child busses 2 and 3 populated with 4
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* PHYs each.
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*/
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mdio-mux {
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compatible = "mdio-mux-gpio";
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gpios = <&gpio1 3 0>, <&gpio1 4 0>;
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mdio-parent-bus = <&smi1>;
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#address-cells = <1>;
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#size-cells = <0>;
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mdio@2 {
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reg = <2>;
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#address-cells = <1>;
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#size-cells = <0>;
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phy11: ethernet-phy@1 {
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reg = <1>;
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compatible = "marvell,88e1149r";
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marvell,reg-init = <3 0x10 0 0x5777>,
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<3 0x11 0 0x00aa>,
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<3 0x12 0 0x4105>,
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<3 0x13 0 0x0a60>;
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interrupt-parent = <&gpio>;
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interrupts = <10 8>; /* Pin 10, active low */
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};
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phy12: ethernet-phy@2 {
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reg = <2>;
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compatible = "marvell,88e1149r";
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marvell,reg-init = <3 0x10 0 0x5777>,
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<3 0x11 0 0x00aa>,
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<3 0x12 0 0x4105>,
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<3 0x13 0 0x0a60>;
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interrupt-parent = <&gpio>;
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interrupts = <10 8>; /* Pin 10, active low */
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};
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phy13: ethernet-phy@3 {
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reg = <3>;
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compatible = "marvell,88e1149r";
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marvell,reg-init = <3 0x10 0 0x5777>,
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<3 0x11 0 0x00aa>,
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<3 0x12 0 0x4105>,
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<3 0x13 0 0x0a60>;
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interrupt-parent = <&gpio>;
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interrupts = <10 8>; /* Pin 10, active low */
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};
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phy14: ethernet-phy@4 {
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reg = <4>;
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compatible = "marvell,88e1149r";
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marvell,reg-init = <3 0x10 0 0x5777>,
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<3 0x11 0 0x00aa>,
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<3 0x12 0 0x4105>,
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<3 0x13 0 0x0a60>;
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interrupt-parent = <&gpio>;
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interrupts = <10 8>; /* Pin 10, active low */
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};
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};
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mdio@3 {
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reg = <3>;
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#address-cells = <1>;
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#size-cells = <0>;
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phy21: ethernet-phy@1 {
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reg = <1>;
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compatible = "marvell,88e1149r";
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marvell,reg-init = <3 0x10 0 0x5777>,
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<3 0x11 0 0x00aa>,
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<3 0x12 0 0x4105>,
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<3 0x13 0 0x0a60>;
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interrupt-parent = <&gpio>;
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interrupts = <12 8>; /* Pin 12, active low */
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};
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phy22: ethernet-phy@2 {
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reg = <2>;
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compatible = "marvell,88e1149r";
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marvell,reg-init = <3 0x10 0 0x5777>,
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<3 0x11 0 0x00aa>,
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<3 0x12 0 0x4105>,
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<3 0x13 0 0x0a60>;
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interrupt-parent = <&gpio>;
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interrupts = <12 8>; /* Pin 12, active low */
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};
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phy23: ethernet-phy@3 {
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reg = <3>;
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compatible = "marvell,88e1149r";
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marvell,reg-init = <3 0x10 0 0x5777>,
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<3 0x11 0 0x00aa>,
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<3 0x12 0 0x4105>,
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<3 0x13 0 0x0a60>;
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interrupt-parent = <&gpio>;
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interrupts = <12 8>; /* Pin 12, active low */
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};
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phy24: ethernet-phy@4 {
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reg = <4>;
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compatible = "marvell,88e1149r";
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marvell,reg-init = <3 0x10 0 0x5777>,
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<3 0x11 0 0x00aa>,
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<3 0x12 0 0x4105>,
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<3 0x13 0 0x0a60>;
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interrupt-parent = <&gpio>;
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interrupts = <12 8>; /* Pin 12, active low */
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};
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};
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};
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