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