Documentation/devicetree/bindings/i2c/i2c-mux-gpmux.yaml

   1 # SPDX-License-Identifier: GPL-2.0
   2 %YAML 1.2
   3 ---
   4 $id: http://devicetree.org/schemas/i2c/i2c-mux-gpmux.yaml#
   5 $schema: http://devicetree.org/meta-schemas/core.yaml#
   6
   7 title: General Purpose I2C Bus Mux
   8
   9 maintainers:
  10   - Peter Rosin <peda@axentia.se>
  11
  12 description: |+
  13   This binding describes an I2C bus multiplexer that uses a mux controller
  14   from the mux subsystem to route the I2C signals.
  15
  16                                     .-----.  .-----.
  17                                     | dev |  | dev |
  18       .------------.                '-----'  '-----'
  19       | SoC        |                   |        |
  20       |            |          .--------+--------'
  21       |   .------. |  .------+    child bus A, on MUX value set to 0
  22       |   | I2C  |-|--| Mux  |
  23       |   '------' |  '--+---+    child bus B, on MUX value set to 1
  24       |   .------. |     |    '----------+--------+--------.
  25       |   | MUX- | |     |               |        |        |
  26       |   | Ctrl |-|-----+            .-----.  .-----.  .-----.
  27       |   '------' |                  | dev |  | dev |  | dev |
  28       '------------'                  '-----'  '-----'  '-----'
  29
  30
  31
  32 allOf:
  33   - $ref: /schemas/i2c/i2c-mux.yaml#
  34
  35 properties:
  36   compatible:
  37     const: i2c-mux
  38
  39   i2c-parent:
  40     $ref: /schemas/types.yaml#/definitions/phandle
  41     description:
  42       The phandle of the I2C bus that this multiplexer's master-side port is
  43       connected to.
  44
  45   mux-controls:
  46     maxItems: 1
  47     description:
  48       The mux-controller states are the I2C sub-bus numbers.
  49
  50   mux-locked:
  51     type: boolean
  52     description: |
  53       Explicitly allow unrelated I2C transactions on the parent I2C adapter at
  54       these times:
  55        - during setup of the multiplexer
  56        - between setup of the multiplexer and the child bus I2C transaction
  57        - between the child bus I2C transaction and releasing of the multiplexer
  58        - during releasing of the multiplexer
  59
  60       However, I2C transactions to devices behind all I2C multiplexers connected
  61       to the same parent adapter that this multiplexer is connected to are blocked
  62       for the full duration of the complete multiplexed I2C transaction (i.e.
  63       including the times covered by the above list).
  64       If mux-locked is not present, the multiplexer is assumed to be parent-locked.
  65       This means that no unrelated I2C transactions are allowed on the parent I2C
  66       adapter for the complete multiplexed I2C transaction.
  67       The properties of mux-locked and parent-locked multiplexers are discussed
  68       in more detail in Documentation/i2c/i2c-topology.rst.
  69
  70 required:
  71   - compatible
  72   - i2c-parent
  73   - mux-controls
  74
  75 unevaluatedProperties: false
  76
  77 examples:
  78   - |
  79     #include <dt-bindings/gpio/gpio.h>
  80     mux: mux-controller {
  81         compatible = "gpio-mux";
  82         #mux-control-cells = <0>;
  83
  84         mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>,
  85                     <&pioA 1 GPIO_ACTIVE_HIGH>;
  86     };
  87
  88     i2c-mux {
  89         compatible = "i2c-mux";
  90         mux-locked;
  91         i2c-parent = <&i2c1>;
  92
  93         mux-controls = <&mux>;
  94
  95         #address-cells = <1>;
  96         #size-cells = <0>;
  97
  98         i2c@1 {
  99             reg = <1>;
 100             #address-cells = <1>;
 101             #size-cells = <0>;
 102
 103             gpio@20 {
 104                 compatible = "nxp,pca9555";
 105                 gpio-controller;
 106                 #gpio-cells = <2>;
 107                 reg = <0x20>;
 108             };
 109         };
 110
 111         i2c@3 {
 112             reg = <3>;
 113             #address-cells = <1>;
 114             #size-cells = <0>;
 115
 116             gpio@20 {
 117                 compatible = "nxp,pca9555";
 118                 gpio-controller;
 119                 #gpio-cells = <2>;
 120                 reg = <0x20>;
 121             };
 122         };
 123     };
 124 ...