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Add binding documentation for the spi-mux driver. This allows a generic multiplexer to be used to provide access to multiple SPI devices. Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz> Reviewed-by: Rob Herring <robh@kernel.org> Link: https://lore.kernel.org/r/20200204032838.20739-2-chris.packham@alliedtelesis.co.nz Signed-off-by: Mark Brown <broonie@kernel.org>
90 lines
2.7 KiB
YAML
90 lines
2.7 KiB
YAML
# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/spi/spi-mux.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: Generic SPI Multiplexer
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description: |
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This binding describes a SPI bus multiplexer to route the SPI chip select
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signals. This can be used when you need more devices than the SPI controller
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has chip selects available. An example setup is shown in ASCII art; the actual
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setting of the multiplexer to a channel needs to be done by a specific SPI mux
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driver.
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MOSI /--------------------------------+--------+--------+--------\
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MISO |/------------------------------+|-------+|-------+|-------\|
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SCL ||/----------------------------+||------+||------+||------\||
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||| ||| ||| ||| |||
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+------------+ ||| ||| ||| |||
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| SoC ||| | +-+++-+ +-+++-+ +-+++-+ +-+++-+
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| ||| | | dev | | dev | | dev | | dev |
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| +--+++-+ | CS-X +------+\ +--+--+ +--+--+ +--+--+ +--+--+
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| | SPI +-|-------+ Mux |\\ CS-0 | | | |
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| +------+ | +--+---+\\\-------/ CS-1 | | |
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| | | \\\----------------/ CS-2 | |
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| +------+ | | \\-------------------------/ CS-3 |
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| | ? +-|----------/ \----------------------------------/
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| +------+ |
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+------------+
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allOf:
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- $ref: "/schemas/spi/spi-controller.yaml#"
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maintainers:
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- Chris Packham <chris.packham@alliedtelesis.co.nz>
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properties:
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compatible:
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const: spi-mux
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mux-controls:
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maxItems: 1
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required:
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- compatible
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- reg
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- spi-max-frequency
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- mux-controls
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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 = <&gpio0 3 GPIO_ACTIVE_HIGH>;
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};
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spi {
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#address-cells = <1>;
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#size-cells = <0>;
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spi@0 {
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compatible = "spi-mux";
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reg = <0>;
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#address-cells = <1>;
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#size-cells = <0>;
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spi-max-frequency = <100000000>;
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mux-controls = <&mux>;
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spi-flash@0 {
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compatible = "jedec,spi-nor";
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reg = <0>;
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#address-cells = <1>;
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#size-cells = <0>;
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spi-max-frequency = <40000000>;
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};
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spi-device@1 {
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compatible = "lineartechnology,ltc2488";
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reg = <1>;
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#address-cells = <1>;
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#size-cells = <0>;
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spi-max-frequency = <10000000>;
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};
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};
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};
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