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>
This commit is contained in:
Marek Behún 2019-08-12 18:11:15 +02:00 committed by Arnd Bergmann
parent 5bc7f990cd
commit 20e6cf7e74
2 changed files with 47 additions and 0 deletions

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Turris Mox module status and configuration bus (over SPI)
Required properties:
- compatible : Should be "cznic,moxtet"
- #address-cells : Has to be 1
- #size-cells : Has to be 0
- spi-cpol : Required inverted clock polarity
- spi-cpha : Required shifted clock phase
- interrupts : Must contain reference to the shared interrupt line
- interrupt-controller : Required
- #interrupt-cells : Has to be 1
For other required and optional properties of SPI slave nodes please refer to
../spi/spi-bus.txt.
Required properties of subnodes:
- reg : Should be position on the Moxtet bus (how many Moxtet
modules are between this module and CPU module, so
either 0 or a positive integer)
The driver finds the devices connected to the bus by itself, but it may be
needed to reference some of them from other parts of the device tree. In that
case the devices can be defined as subnodes of the moxtet node.
Example:
moxtet@1 {
compatible = "cznic,moxtet";
#address-cells = <1>;
#size-cells = <0>;
reg = <1>;
spi-max-frequency = <10000000>;
spi-cpol;
spi-cpha;
interrupt-controller;
#interrupt-cells = <1>;
interrupt-parent = <&gpiosb>;
interrupts = <5 IRQ_TYPE_EDGE_FALLING>;
moxtet_sfp: gpio@0 {
compatible = "cznic,moxtet-gpio";
gpio-controller;
#gpio-cells = <2>;
reg = <0>;
}
};

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@ -1630,6 +1630,7 @@ ARM/CZ.NIC TURRIS MOX SUPPORT
M: Marek Behun <marek.behun@nic.cz>
W: http://mox.turris.cz
S: Maintained
F: Documentation/devicetree/bindings/bus/moxtet.txt
F: include/linux/moxtet.h
F: drivers/bus/moxtet.c