125 lines
3.6 KiB
YAML
125 lines
3.6 KiB
YAML
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# SPDX-License-Identifier: GPL-2.0
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/i2c/i2c-mux-gpmux.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: General Purpose I2C Bus Mux
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maintainers:
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- Peter Rosin <peda@axentia.se>
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description: |+
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This binding describes an I2C bus multiplexer that uses a mux controller
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from the mux subsystem to route the I2C signals.
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.-----. .-----.
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| dev | | dev |
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.------------. '-----' '-----'
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| SoC | | |
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| | .--------+--------'
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| .------. | .------+ child bus A, on MUX value set to 0
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| | I2C |-|--| Mux |
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| '------' | '--+---+ child bus B, on MUX value set to 1
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| .------. | | '----------+--------+--------.
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| | MUX- | | | | | |
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| | Ctrl |-|-----+ .-----. .-----. .-----.
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| '------' | | dev | | dev | | dev |
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'------------' '-----' '-----' '-----'
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allOf:
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- $ref: /schemas/i2c/i2c-mux.yaml#
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properties:
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compatible:
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const: i2c-mux
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i2c-parent:
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$ref: /schemas/types.yaml#/definitions/phandle
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description:
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The phandle of the I2C bus that this multiplexer's master-side port is
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connected to.
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mux-controls:
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maxItems: 1
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description:
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The mux-controller states are the I2C sub-bus numbers.
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mux-locked:
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type: boolean
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description: |
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Explicitly allow unrelated I2C transactions on the parent I2C adapter at
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these times:
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- during setup of the multiplexer
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- between setup of the multiplexer and the child bus I2C transaction
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- between the child bus I2C transaction and releasing of the multiplexer
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- during releasing of the multiplexer
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However, I2C transactions to devices behind all I2C multiplexers connected
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to the same parent adapter that this multiplexer is connected to are blocked
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for the full duration of the complete multiplexed I2C transaction (i.e.
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including the times covered by the above list).
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If mux-locked is not present, the multiplexer is assumed to be parent-locked.
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This means that no unrelated I2C transactions are allowed on the parent I2C
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adapter for the complete multiplexed I2C transaction.
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The properties of mux-locked and parent-locked multiplexers are discussed
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in more detail in Documentation/i2c/i2c-topology.rst.
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required:
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- compatible
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- i2c-parent
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- mux-controls
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unevaluatedProperties: false
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examples:
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- |
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#include <dt-bindings/gpio/gpio.h>
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mux: mux-controller {
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compatible = "gpio-mux";
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#mux-control-cells = <0>;
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mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>,
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<&pioA 1 GPIO_ACTIVE_HIGH>;
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};
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i2c-mux {
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compatible = "i2c-mux";
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mux-locked;
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i2c-parent = <&i2c1>;
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mux-controls = <&mux>;
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#address-cells = <1>;
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#size-cells = <0>;
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i2c@1 {
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reg = <1>;
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#address-cells = <1>;
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#size-cells = <0>;
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gpio@20 {
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compatible = "nxp,pca9555";
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gpio-controller;
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#gpio-cells = <2>;
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reg = <0x20>;
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};
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};
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i2c@3 {
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reg = <3>;
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#address-cells = <1>;
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#size-cells = <0>;
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gpio@20 {
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compatible = "nxp,pca9555";
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gpio-controller;
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#gpio-cells = <2>;
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reg = <0x20>;
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};
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};
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};
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...
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