0001 # SPDX-License-Identifier: GPL-2.0
0002 %YAML 1.2
0003 ---
0004 $id: http://devicetree.org/schemas/i2c/i2c-mux-gpmux.yaml#
0005 $schema: http://devicetree.org/meta-schemas/core.yaml#
0006
0007 title: General Purpose I2C Bus Mux
0008
0009 maintainers:
0010 - Peter Rosin <peda@axentia.se>
0011
0012 description: |+
0013 This binding describes an I2C bus multiplexer that uses a mux controller
0014 from the mux subsystem to route the I2C signals.
0015
0016 .-----. .-----.
0017 | dev | | dev |
0018 .------------. '-----' '-----'
0019 | SoC | | |
0020 | | .--------+--------'
0021 | .------. | .------+ child bus A, on MUX value set to 0
0022 | | I2C |-|--| Mux |
0023 | '------' | '--+---+ child bus B, on MUX value set to 1
0024 | .------. | | '----------+--------+--------.
0025 | | MUX- | | | | | |
0026 | | Ctrl |-|-----+ .-----. .-----. .-----.
0027 | '------' | | dev | | dev | | dev |
0028 '------------' '-----' '-----' '-----'
0029
0030
0031 allOf:
0032 - $ref: /schemas/i2c/i2c-mux.yaml#
0033
0034 properties:
0035 compatible:
0036 const: i2c-mux
0037
0038 i2c-parent:
0039 $ref: /schemas/types.yaml#/definitions/phandle
0040 description:
0041 The phandle of the I2C bus that this multiplexer's master-side port is
0042 connected to.
0043
0044 mux-controls:
0045 maxItems: 1
0046 description:
0047 The mux-controller states are the I2C sub-bus numbers.
0048
0049 mux-locked:
0050 type: boolean
0051 description: |
0052 Explicitly allow unrelated I2C transactions on the parent I2C adapter at
0053 these times:
0054 - during setup of the multiplexer
0055 - between setup of the multiplexer and the child bus I2C transaction
0056 - between the child bus I2C transaction and releasing of the multiplexer
0057 - during releasing of the multiplexer
0058
0059 However, I2C transactions to devices behind all I2C multiplexers connected
0060 to the same parent adapter that this multiplexer is connected to are blocked
0061 for the full duration of the complete multiplexed I2C transaction (i.e.
0062 including the times covered by the above list).
0063 If mux-locked is not present, the multiplexer is assumed to be parent-locked.
0064 This means that no unrelated I2C transactions are allowed on the parent I2C
0065 adapter for the complete multiplexed I2C transaction.
0066 The properties of mux-locked and parent-locked multiplexers are discussed
0067 in more detail in Documentation/i2c/i2c-topology.rst.
0068
0069 required:
0070 - compatible
0071 - i2c-parent
0072 - mux-controls
0073
0074 unevaluatedProperties: false
0075
0076 examples:
0077 - |
0078 #include <dt-bindings/gpio/gpio.h>
0079 mux: mux-controller {
0080 compatible = "gpio-mux";
0081 #mux-control-cells = <0>;
0082
0083 mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>,
0084 <&pioA 1 GPIO_ACTIVE_HIGH>;
0085 };
0086
0087 i2c-mux {
0088 compatible = "i2c-mux";
0089 mux-locked;
0090 i2c-parent = <&i2c1>;
0091
0092 mux-controls = <&mux>;
0093
0094 #address-cells = <1>;
0095 #size-cells = <0>;
0096
0097 i2c@1 {
0098 reg = <1>;
0099 #address-cells = <1>;
0100 #size-cells = <0>;
0101
0102 gpio@20 {
0103 compatible = "nxp,pca9555";
0104 gpio-controller;
0105 #gpio-cells = <2>;
0106 reg = <0x20>;
0107 };
0108 };
0109
0110 i2c@3 {
0111 reg = <3>;
0112 #address-cells = <1>;
0113 #size-cells = <0>;
0114
0115 gpio@20 {
0116 compatible = "nxp,pca9555";
0117 gpio-controller;
0118 #gpio-cells = <2>;
0119 reg = <0x20>;
0120 };
0121 };
0122 };
0123 ...
