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1# SPDX-License-Identifier: GPL-2.0-only2%YAML 1.23---4$id: http://devicetree.org/schemas/i2c/i2c-mux-gpio.yaml#5$schema: http://devicetree.org/meta-schemas/core.yaml#6 7title: GPIO-based I2C Bus Mux8 9maintainers:10 - Wolfram Sang <wsa@kernel.org>11 12description: |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 021 | | I2C |-|--| Mux |22 | +------+ | +--+---+ child bus B, on GPIO value set to 123 | | | \----------+--------+--------+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 their30 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 reg33 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 not37 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 into40 hardware whenever no access is being made to a device on a child bus.41 42properties:43 compatible:44 const: i2c-mux-gpio45 46 i2c-parent:47 description: phandle of the I2C bus that this multiplexer's master-side port is connected to48 $ref: /schemas/types.yaml#/definitions/phandle49 50 mux-gpios:51 description: list of GPIOs used to control the muxer52 minItems: 153 maxItems: 4 # Should be enough54 55 idle-state:56 description: Value to set the muxer to when idle. When no value is given, it defaults to the57 last value used.58 $ref: /schemas/types.yaml#/definitions/uint3259 60 settle-time-us:61 description: Delay to wait before doing any transfer when a new bus gets selected.62 63allOf:64 - $ref: i2c-mux.yaml65 66unevaluatedProperties: false67 68required:69 - compatible70 - i2c-parent71 - mux-gpios72 73examples:74 - |75 i2cmux {76 compatible = "i2c-mux-gpio";77 #address-cells = <1>;78 #size-cells = <0>;79 mux-gpios = <&gpio1 22 0>, <&gpio1 23 0>;80 i2c-parent = <&i2c1>;81 82 i2c@1 {83 reg = <1>;84 #address-cells = <1>;85 #size-cells = <0>;86 87 ssd1307: oled@3c {88 compatible = "solomon,ssd1307fb-i2c";89 reg = <0x3c>;90 pwms = <&pwm 4 3000>;91 reset-gpios = <&gpio2 7 1>;92 };93 };94 95 i2c@3 {96 reg = <3>;97 #address-cells = <1>;98 #size-cells = <0>;99 100 pca9555: pca9555@20 {101 compatible = "nxp,pca9555";102 gpio-controller;103 #gpio-cells = <2>;104 reg = <0x20>;105 };106 };107 };108