207 lines
5.9 KiB
YAML
207 lines
5.9 KiB
YAML
# SPDX-License-Identifier: GPL-2.0
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/mux/mux-controller.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: Common multiplexer controller provider
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maintainers:
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- Peter Rosin <peda@axentia.se>
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description: |
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A multiplexer (or mux) controller will have one, or several, consumer devices
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that uses the mux controller. Thus, a mux controller can possibly control
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several parallel multiplexers. Presumably there will be at least one
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multiplexer needed by each consumer, but a single mux controller can of course
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control several multiplexers for a single consumer.
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A mux controller provides a number of states to its consumers, and the state
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space is a simple zero-based enumeration. I.e. 0-1 for a 2-way multiplexer,
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0-7 for an 8-way multiplexer, etc.
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Mux controller nodes
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--------------------
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Mux controller nodes must specify the number of cells used for the
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specifier using the '#mux-control-cells' or '#mux-state-cells' property.
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The value of '#mux-state-cells' will always be one greater than the value
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of '#mux-control-cells'.
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Optionally, mux controller nodes can also specify the state the mux should
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have when it is idle. The idle-state property is used for this. If the
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idle-state is not present, the mux controller is typically left as is when
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it is idle. For multiplexer chips that expose several mux controllers, the
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idle-state property is an array with one idle state for each mux controller.
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The special value (-1) may be used to indicate that the mux should be left
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as is when it is idle. This is the default, but can still be useful for
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mux controller chips with more than one mux controller, particularly when
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there is a need to "step past" a mux controller and set some other idle
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state for a mux controller with a higher index.
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Some mux controllers have the ability to disconnect the input/output of the
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multiplexer. Using this disconnected high-impedance state as the idle state
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is indicated with idle state (-2).
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These constants are available in
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#include <dt-bindings/mux/mux.h>
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as MUX_IDLE_AS_IS (-1) and MUX_IDLE_DISCONNECT (-2).
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An example mux controller node look like this (the adg972a chip is a triple
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4-way multiplexer):
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mux: mux-controller@50 {
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compatible = "adi,adg792a";
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reg = <0x50>;
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#mux-control-cells = <1>;
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idle-state = <MUX_IDLE_DISCONNECT MUX_IDLE_AS_IS 2>;
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};
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select:
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anyOf:
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- properties:
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$nodename:
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pattern: '^mux-controller'
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- required:
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- '#mux-control-cells'
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- required:
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- '#mux-state-cells'
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properties:
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$nodename:
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pattern: '^mux-controller(@.*|-[0-9a-f]+)?$'
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'#mux-control-cells':
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enum: [ 0, 1 ]
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'#mux-state-cells':
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enum: [ 1, 2 ]
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idle-state:
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$ref: /schemas/types.yaml#/definitions/int32
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minimum: -2
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idle-states:
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description: |
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Mux controller nodes can specify the state the mux should have when it is
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idle. If the idle-state is not present, the mux controller is typically
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left as is when it is idle. For multiplexer chips that expose several mux
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controllers, the idle-state property is an array with one idle state for
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each mux controller.
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The special value (-1) may be used to indicate that the mux should be left
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as is when it is idle. This is the default, but can still be useful for
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mux controller chips with more than one mux controller, particularly when
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there is a need to "step past" a mux controller and set some other idle
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state for a mux controller with a higher index.
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Some mux controllers have the ability to disconnect the input/output of the
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multiplexer. Using this disconnected high-impedance state as the idle state
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is indicated with idle state (-2).
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$ref: /schemas/types.yaml#/definitions/int32-array
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items:
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minimum: -2
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additionalProperties: true
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examples:
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- |
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#include <dt-bindings/gpio/gpio.h>
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/* One consumer of a 2-way mux controller (one GPIO-line) */
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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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};
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adc-mux {
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compatible = "io-channel-mux";
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io-channels = <&adc 0>;
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io-channel-names = "parent";
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mux-controls = <&mux>;
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mux-control-names = "adc";
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channels = "sync", "in";
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};
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- |
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#include <dt-bindings/gpio/gpio.h>
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/*
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* Two consumers (one for an ADC line and one for an i2c bus) of
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* parallel 4-way multiplexers controlled by the same two GPIO-lines.
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*/
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mux2: 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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adc-mux {
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compatible = "io-channel-mux";
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io-channels = <&adc 0>;
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io-channel-names = "parent";
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mux-controls = <&mux2>;
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channels = "sync-1", "in", "out", "sync-2";
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};
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i2c-mux {
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compatible = "i2c-mux";
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i2c-parent = <&i2c1>;
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mux-controls = <&mux2>;
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#address-cells = <1>;
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#size-cells = <0>;
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i2c@0 {
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reg = <0>;
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#address-cells = <1>;
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#size-cells = <0>;
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ssd1307: oled@3c {
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reg = <0x3c>;
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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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pca9555: pca9555@20 {
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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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#include <dt-bindings/gpio/gpio.h>
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mux1: mux-controller {
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compatible = "gpio-mux";
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#mux-state-cells = <1>;
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mux-gpios = <&exp_som 2 GPIO_ACTIVE_HIGH>;
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};
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transceiver4: can-phy4 {
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compatible = "ti,tcan1042";
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#phy-cells = <0>;
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max-bitrate = <5000000>;
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standby-gpios = <&exp_som 7 GPIO_ACTIVE_HIGH>;
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mux-states = <&mux1 1>;
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};
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...
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