iio: proximity: as3935: add missing required spi-max-frequency

spi-max-frequency is required to be set for the as3935 part, and
document such usage.

Cc: devicetree@vger.kernel.org
Signed-off-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Rob Herring <robh@kernel.org>

diff --git a/Documentation/devicetree/bindings/iio/proximity/as3935.txt b/Documentation/devicetree/bindings/iio/proximity/as3935.txt
index ae23dd8..38d7431 100644 (file)
--- a/Documentation/devicetree/bindings/iio/proximity/as3935.txt
+++ b/Documentation/devicetree/bindings/iio/proximity/as3935.txt
@@ -3,6 +3,7 @@ Austrian Microsystems AS3935 Franklin lightning sensor device driver
 Required properties:
        - compatible: must be "ams,as3935"
        - reg: SPI chip select number for the device
+       - spi-max-frequency: specifies maximum SPI clock frequency
        - spi-cpha: SPI Mode 1. Refer to spi/spi-bus.txt for generic SPI
        slave node bindings.
        - interrupt-parent : should be the phandle for the interrupt controller
@@ -21,6 +22,7 @@ Example:
 as3935@0 {
        compatible = "ams,as3935";
        reg = <0>;
+       spi-max-frequency = <400000>;
        spi-cpha;
        interrupt-parent = <&gpio1>;
        interrupts = <16 1>;