Kernel-4.18.0-80.el8_i2c-mux

Common i2c bus multiplexer/switch properties.

An i2c bus multiplexer/switch will have several child busses that are
numbered uniquely in a device dependent manner. The nodes for an i2c bus
multiplexer/switch will have one child node for each child bus.

Optional properties:

• #address-cells = <1>;
  This property is required if the i2c-mux child node does not exist.

• #size-cells = <0>;
  This property is required if the i2c-mux child node does not exist.

• i2c-mux
  For i2c multiplexers/switches that have child nodes that are a mixture
  of both i2c child busses and other child nodes, the ‘i2c-mux’ subnode
  can be used for populating the i2c child busses. If an ‘i2c-mux’
  subnode is present, only subnodes of this will be considered as i2c
  child busses.

Required properties for the i2c-mux child node:

• #address-cells = <1>;
• #size-cells = <0>;

Required properties for i2c child bus nodes:

• #address-cells = <1>;
• #size-cells = <0>;
• reg : The sub-bus number.

Optional properties for i2c child bus nodes:

• Other properties specific to the multiplexer/switch hardware.
• Child nodes conforming to i2c bus binding

Example :

/*
   An NXP pca9548 8 channel I2C multiplexer at address 0x70
   with two NXP pca8574 GPIO expanders attached, one each to
   ports 3 and 4.
 */

mux@70 {
    compatible = "nxp,pca9548";
    reg = <0x70>;
    #address-cells = <1>;
    #size-cells = <0>;

    i2c@3 {
        #address-cells = <1>;
        #size-cells = <0>;
        reg = <3>;

        gpio1: gpio@38 {
            compatible = "nxp,pca8574";
            reg = <0x38>;
            #gpio-cells = <2>;
            gpio-controller;
        };
    };
    i2c@4 {
        #address-cells = <1>;
        #size-cells = <0>;
        reg = <4>;

        gpio2: gpio@38 {
            compatible = "nxp,pca8574";
            reg = <0x38>;
            #gpio-cells = <2>;
            gpio-controller;
        };
    };
};