gpio: Add XRA1403 DTS binding documentation

Add the XRA1403 DTS binding documentation.

Signed-off-by: Nandor Han <nandor.han@ge.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/Documentation/devicetree/bindings/gpio/gpio-xra1403.txt b/Documentation/devicetree/bindings/gpio/gpio-xra1403.txt
new file mode 100644 (file)
index 0000000..e13cc39
--- /dev/null
+++ b/Documentation/devicetree/bindings/gpio/gpio-xra1403.txt
@@ -0,0 +1,46 @@
+GPIO Driver for XRA1403 16-BIT GPIO Expander With Reset Input from EXAR
+
+The XRA1403 is an 16-bit GPIO expander with an SPI interface. Features available:
+       - Individually programmable inputs:
+               - Internal pull-up resistors
+               - Polarity inversion
+               - Individual interrupt enable
+               - Rising edge and/or Falling edge interrupt
+               - Input filter
+       - Individually programmable outputs
+               - Output Level Control
+               - Output Three-State Control
+
+Properties
+----------
+Check documentation for SPI and GPIO controllers regarding properties needed to configure the node.
+
+       - compatible = "exar,xra1403".
+       - reg - SPI id of the device.
+       - gpio-controller - marks the node as gpio.
+       - #gpio-cells - should be two where the first cell is the pin number
+               and the second one is used for optional parameters.
+
+Optional properties:
+-------------------
+       - reset-gpios: in case available used to control the device reset line.
+       - interrupt-controller - marks the node as interrupt controller.
+       - #interrupt-cells - should be two and represents the number of cells
+               needed to encode interrupt source.
+
+Example
+--------
+
+       gpioxra0: gpio@2 {
+               compatible = "exar,xra1403";
+               reg = <2>;
+
+               gpio-controller;
+               #gpio-cells = <2>;
+
+               interrupt-controller;
+               #interrupt-cells = <2>;
+
+               reset-gpios = <&gpio3 6 GPIO_ACTIVE_LOW>;
+               spi-max-frequency = <1000000>;
+       };