i2c-mux-gpio.yaml

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    1 # SPDX-License-Identifier: GPL-2.0-only
    2 %YAML 1.2
    3 ---
    4 $id: http://devicetree.org/schemas/i2c/i2c-mux-gpio.yaml#
    5 $schema: http://devicetree.org/meta-schemas/core.yaml#
    6 
    7 title: GPIO-based I2C Bus Mux
    8 
    9 maintainers:
   10   - Wolfram Sang <wsa@kernel.org>
   11 
   12 description: |
   13   This binding describes an I2C bus multiplexer that uses GPIOs to route the I2C signals.
   14 
   15                                   +-----+  +-----+
   16                                   | dev |  | dev |
   17     +------------+                +-----+  +-----+
   18     | SoC        |                   |        |
   19     |            |          /--------+--------+
   20     |   +------+ |  +------+    child bus A, on GPIO value set to 0
   21     |   | I2C  |-|--| Mux  |
   22     |   +------+ |  +--+---+    child bus B, on GPIO value set to 1
   23     |            |     |    \----------+--------+--------+
   24     |   +------+ |     |               |        |        |
   25     |   | GPIO |-|-----+            +-----+  +-----+  +-----+
   26     |   +------+ |                  | dev |  | dev |  | dev |
   27     +------------+                  +-----+  +-----+  +-----+
   28 
   29   For each I2C child node, an I2C child bus will be created. They will be numbered based on their
   30   order in the device tree.
   31 
   32   Whenever an access is made to a device on a child bus, the value set in the relevant node's reg
   33   property will be output using the list of GPIOs, the first in the list holding the least-
   34   significant value.
   35 
   36   If an idle state is defined, using the idle-state (optional) property, whenever an access is not
   37   being made to a device on a child bus, the GPIOs will be set according to the idle value.
   38 
   39   If an idle state is not defined, the most recently used value will be left programmed into
   40   hardware whenever no access is being made to a device on a child bus.
   41 
   42 properties:
   43   compatible:
   44     const: i2c-mux-gpio
   45 
   46   i2c-parent:
   47     description: phandle of the I2C bus that this multiplexer's master-side port is connected to
   48     $ref: "/schemas/types.yaml#/definitions/phandle"
   49 
   50   mux-gpios:
   51     description: list of GPIOs used to control the muxer
   52     minItems: 1
   53     maxItems: 4  # Should be enough
   54 
   55   idle-state:
   56     description: Value to set the muxer to when idle. When no value is given, it defaults to the
   57       last value used.
   58     $ref: "/schemas/types.yaml#/definitions/uint32"
   59 
   60 allOf:
   61   - $ref: i2c-mux.yaml
   62 
   63 unevaluatedProperties: false
   64 
   65 required:
   66   - compatible
   67   - i2c-parent
   68   - mux-gpios
   69 
   70 examples:
   71   - |
   72     i2cmux {
   73       compatible = "i2c-mux-gpio";
   74       #address-cells = <1>;
   75       #size-cells = <0>;
   76       mux-gpios = <&gpio1 22 0>, <&gpio1 23 0>;
   77       i2c-parent = <&i2c1>;
   78 
   79       i2c@1 {
   80         reg = <1>;
   81         #address-cells = <1>;
   82         #size-cells = <0>;
   83 
   84         ssd1307: oled@3c {
   85           compatible = "solomon,ssd1307fb-i2c";
   86           reg = <0x3c>;
   87           pwms = <&pwm 4 3000>;
   88           reset-gpios = <&gpio2 7 1>;
   89         };
   90       };
   91 
   92       i2c@3 {
   93         reg = <3>;
   94         #address-cells = <1>;
   95         #size-cells = <0>;
   96 
   97         pca9555: pca9555@20 {
   98           compatible = "nxp,pca9555";
   99           gpio-controller;
  100           #gpio-cells = <2>;
  101           reg = <0x20>;
  102         };
  103       };
  104     };

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FreeBSD/Linux Kernel Cross Reference sys/contrib/device-tree/Bindings/i2c/i2c-mux-gpio.yaml

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sys/contrib/device-tree/Bindings/i2c/i2c-mux-gpio.yaml