dt-bindings: gpio: Document GPIOs via Moxtet bus

This patch adds documentation of the device tree bindings for GPIOs
on the devices connected via Moxtet bus.

Link: https://lore.kernel.org/r/20190812161118.21476-6-marek.behun@nic.cz
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 18 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/gpio/gpio-moxtet.txt b/Documentation/devicetree/bindings/gpio/gpio-moxtet.txt
new file mode 100644
index 000000000000..410759de9f09
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-moxtet.txt
@@ -0,0 +1,18 @@
+Turris Mox Moxtet GPIO expander via Moxtet bus
+
+Required properties:
+ - compatible		: Should be "cznic,moxtet-gpio".
+ - gpio-controller	: Marks the device node as a GPIO controller.
+ - #gpio-cells		: Should be two. For consumer use see gpio.txt.
+
+Other properties are required for a Moxtet bus device, please refer to
+Documentation/devicetree/bindings/bus/moxtet.txt.
+
+Example:
+
+	moxtet_sfp: gpio@0 {
+		compatible = "cznic,moxtet-gpio";
+		gpio-controller;
+		#gpio-cells = <2>;
+		reg = <0>;
+	}