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author | Thierry Reding <treding@nvidia.com> | 2021-12-17 19:56:58 +0300 |
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committer | Rob Herring <robh@kernel.org> | 2021-12-18 01:39:33 +0300 |
commit | f91030ed4494a0698cc5b3df173f3e125fbd4c87 (patch) | |
tree | 80938f77bf1d279de344f1807325431f54b9206e /Documentation/devicetree/bindings/i2c/i2c-mux-gpio.yaml | |
parent | 8b82b8416f2cb1fdfa2709c7a96e022561e3ed24 (diff) | |
download | linux-f91030ed4494a0698cc5b3df173f3e125fbd4c87.tar.xz |
dt-bindings: i2c: i2c-mux-gpio: Convert to json-schema
Convert the GPIO-based I2C mux bindings from the free-form text format
to json-schema.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211217165658.2650677-4-thierry.reding@gmail.com
Diffstat (limited to 'Documentation/devicetree/bindings/i2c/i2c-mux-gpio.yaml')
-rw-r--r-- | Documentation/devicetree/bindings/i2c/i2c-mux-gpio.yaml | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.yaml b/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.yaml new file mode 100644 index 000000000000..6e0a5686af04 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-gpio.yaml @@ -0,0 +1,104 @@ +# 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>; + }; + }; + }; |