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dt-bindings: bus: Document moxtet bus binding
This adds device tree binding documentation for the Moxtet bus, a bus
via which the different modules connected to the Turris Mox router can
be configured.
Link: https://lore.kernel.org/r/20190812161118.21476-3-marek.behun@nic.cz
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
authored by
Marek Behún
and committed by
Arnd Bergmann
20e6cf7e
5bc7f990
+47
+46
Documentation/devicetree/bindings/bus/moxtet.txt
+46
Documentation/devicetree/bindings/bus/moxtet.txt
···
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Turris Mox module status and configuration bus (over SPI)
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Required properties:
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- compatible : Should be "cznic,moxtet"
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- #address-cells : Has to be 1
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- #size-cells : Has to be 0
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- spi-cpol : Required inverted clock polarity
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- spi-cpha : Required shifted clock phase
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- interrupts : Must contain reference to the shared interrupt line
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- interrupt-controller : Required
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- #interrupt-cells : Has to be 1
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For other required and optional properties of SPI slave nodes please refer to
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../spi/spi-bus.txt.
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Required properties of subnodes:
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- reg : Should be position on the Moxtet bus (how many Moxtet
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modules are between this module and CPU module, so
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either 0 or a positive integer)
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The driver finds the devices connected to the bus by itself, but it may be
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needed to reference some of them from other parts of the device tree. In that
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case the devices can be defined as subnodes of the moxtet node.
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Example:
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moxtet@1 {
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compatible = "cznic,moxtet";
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#address-cells = <1>;
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#size-cells = <0>;
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reg = <1>;
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spi-max-frequency = <10000000>;
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spi-cpol;
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spi-cpha;
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interrupt-controller;
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#interrupt-cells = <1>;
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interrupt-parent = <&gpiosb>;
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interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
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moxtet_sfp: gpio@0 {
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compatible = "cznic,moxtet-gpio";
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gpio-controller;
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#gpio-cells = <2>;
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reg = <0>;
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}
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};