linux/Documentation/devicetree/bindings/i2c/i2c-mux.txt
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   1Common i2c bus multiplexer/switch properties.
   2
   3An i2c bus multiplexer/switch will have several child busses that are
   4numbered uniquely in a device dependent manner.  The nodes for an i2c bus
   5multiplexer/switch will have one child node for each child
   6bus.
   7
   8Required properties:
   9- #address-cells = <1>;
  10- #size-cells = <0>;
  11
  12Required properties for child nodes:
  13- #address-cells = <1>;
  14- #size-cells = <0>;
  15- reg : The sub-bus number.
  16
  17Optional properties for child nodes:
  18- Other properties specific to the multiplexer/switch hardware.
  19- Child nodes conforming to i2c bus binding
  20
  21
  22Example :
  23
  24        /*
  25           An NXP pca9548 8 channel I2C multiplexer at address 0x70
  26           with two NXP pca8574 GPIO expanders attached, one each to
  27           ports 3 and 4.
  28         */
  29
  30        mux@70 {
  31                compatible = "nxp,pca9548";
  32                reg = <0x70>;
  33                #address-cells = <1>;
  34                #size-cells = <0>;
  35
  36                i2c@3 {
  37                        #address-cells = <1>;
  38                        #size-cells = <0>;
  39                        reg = <3>;
  40
  41                        gpio1: gpio@38 {
  42                                compatible = "nxp,pca8574";
  43                                reg = <0x38>;
  44                                #gpio-cells = <2>;
  45                                gpio-controller;
  46                        };
  47                };
  48                i2c@4 {
  49                        #address-cells = <1>;
  50                        #size-cells = <0>;
  51                        reg = <4>;
  52
  53                        gpio2: gpio@38 {
  54                                compatible = "nxp,pca8574";
  55                                reg = <0x38>;
  56                                #gpio-cells = <2>;
  57                                gpio-controller;
  58                        };
  59                };
  60        };
  61