[PATCH v4.1 armsoc/drivers/bus+gpio 2/5] dt-bindings: bus: Document moxtet bus binding

[Marek Behún <marek.behun@xxxxxx>]

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.

Signed-off-by: Marek Behún <marek.behun@xxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: devicetree@xxxxxxxxxxxxxxx
---
 .../devicetree/bindings/bus/moxtet.txt        | 44 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 45 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/bus/moxtet.txt

diff --git a/Documentation/devicetree/bindings/bus/moxtet.txt b/Documentation/devicetree/bindings/bus/moxtet.txt
new file mode 100644
index 000000000000..7be9d00c1767
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/moxtet.txt
@@ -0,0 +1,46 @@
+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>;
+		}
+	};
diff --git a/MAINTAINERS b/MAINTAINERS
index d96d36c83bc3..3f461a2d776a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1502,6 +1502,7 @@ ARM/CZ.NIC TURRIS MOX SUPPORT
 M:	Marek Behun <marek.behun@xxxxxx>
 W:	http://mox.turris.cz
 S:	Maintained
+F:	Documentation/devicetree/bindings/bus/moxtet.txt
 F:	include/linux/moxtet.h
 F:	drivers/bus/moxtet.c
 
-- 
2.19.2