| # SPDX-License-Identifier: GPL-2.0-only |
| %YAML 1.2 |
| --- |
| $id: http://devicetree.org/schemas/i2c/i2c-mux-gpio.yaml# |
| $schema: http://devicetree.org/meta-schemas/core.yaml# |
| |
| title: GPIO-based I2C Bus Mux |
| |
| maintainers: |
| - Wolfram Sang <wsa@kernel.org> |
| |
| description: | |
| This binding describes an I2C bus multiplexer that uses GPIOs to route the I2C signals. |
| |
| +-----+ +-----+ |
| | dev | | dev | |
| +------------+ +-----+ +-----+ |
| | SoC | | | |
| | | /--------+--------+ |
| | +------+ | +------+ child bus A, on GPIO value set to 0 |
| | | I2C |-|--| Mux | |
| | +------+ | +--+---+ child bus B, on GPIO value set to 1 |
| | | | \----------+--------+--------+ |
| | +------+ | | | | | |
| | | GPIO |-|-----+ +-----+ +-----+ +-----+ |
| | +------+ | | dev | | dev | | dev | |
| +------------+ +-----+ +-----+ +-----+ |
| |
| For each I2C child node, an I2C child bus will be created. They will be numbered based on their |
| order in the device tree. |
| |
| Whenever an access is made to a device on a child bus, the value set in the relevant node's reg |
| property will be output using the list of GPIOs, the first in the list holding the least- |
| significant value. |
| |
| If an idle state is defined, using the idle-state (optional) property, whenever an access is not |
| being made to a device on a child bus, the GPIOs will be set according to the idle value. |
| |
| If an idle state is not defined, the most recently used value will be left programmed into |
| hardware whenever no access is being made to a device on a child bus. |
| |
| properties: |
| compatible: |
| const: i2c-mux-gpio |
| |
| i2c-parent: |
| description: phandle of the I2C bus that this multiplexer's master-side port is connected to |
| $ref: "/schemas/types.yaml#/definitions/phandle" |
| |
| mux-gpios: |
| description: list of GPIOs used to control the muxer |
| minItems: 1 |
| maxItems: 4 # Should be enough |
| |
| idle-state: |
| description: Value to set the muxer to when idle. When no value is given, it defaults to the |
| last value used. |
| $ref: "/schemas/types.yaml#/definitions/uint32" |
| |
| allOf: |
| - $ref: i2c-mux.yaml |
| |
| unevaluatedProperties: false |
| |
| required: |
| - compatible |
| - i2c-parent |
| - mux-gpios |
| |
| examples: |
| - | |
| i2cmux { |
| compatible = "i2c-mux-gpio"; |
| #address-cells = <1>; |
| #size-cells = <0>; |
| mux-gpios = <&gpio1 22 0>, <&gpio1 23 0>; |
| i2c-parent = <&i2c1>; |
| |
| i2c@1 { |
| reg = <1>; |
| #address-cells = <1>; |
| #size-cells = <0>; |
| |
| ssd1307: oled@3c { |
| compatible = "solomon,ssd1307fb-i2c"; |
| reg = <0x3c>; |
| pwms = <&pwm 4 3000>; |
| reset-gpios = <&gpio2 7 1>; |
| }; |
| }; |
| |
| i2c@3 { |
| reg = <3>; |
| #address-cells = <1>; |
| #size-cells = <0>; |
| |
| pca9555: pca9555@20 { |
| compatible = "nxp,pca9555"; |
| gpio-controller; |
| #gpio-cells = <2>; |
| reg = <0x20>; |
| }; |
| }; |
| }; |
