[PATCH 1/2] dt-bindings: leds: Add binding for ubnt-spi LED.

[list@c-mauderer.de]

From: Christian Mauderer <oss@c-mauderer.de>

This patch adds the binding documentation for the LED controller found
in Ubiquity airCube ISP devices.

Signed-off-by: Christian Mauderer <oss@c-mauderer.de>
---

I tested the patches with a 4.14 and a 4.19 kernel on the current OpenWRT.
Although I didn't get the kernel running due to file system problems they build
fine with a 5.1-rc7.

I shortly described the protocol of the controller in a comment in the driver
file in the second patch.

Checkpatch gives the following warning for both patches:

  WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?

To be honest: I don't know what to do with it. Please excuse my ignorance here.
It's the first driver that I want to add to the Linux kernel.

Please point me to some documentation if I did miss some big points for
submitting patches.


 .../bindings/leds/leds-ubnt-spi.txt           | 49 +++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/leds-ubnt-spi.txt

diff --git a/Documentation/devicetree/bindings/leds/leds-ubnt-spi.txt b/Documentation/devicetree/bindings/leds/leds-ubnt-spi.txt
new file mode 100644
index 000000000000..ab1478cdc139
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/leds-ubnt-spi.txt
@@ -0,0 +1,49 @@
+Binding for the controller based LED found in Ubiquity airCube ISP and most
+likely some other Ubiquity devices.
+
+The protocol of the controller is quite simple. Only one byte will be sent. The
+value of the byte can be between the ubnt-spi,off_bright value and the
+ubnt-spi,max_bright value.
+
+The driver maybe can be used for other devices with a similar protocol too.
+
+Required properties:
+- compatible:		Should be "ubnt,spi-led".
+- spi-max-frequency:	Should be <100000> for this device.
+
+Optional sub-node properties:
+- ubnt-spi,off_bright:	The value that will be sent if the LED should be
+			switched off. Default value is 0.
+- ubnt-spi,max_bright:	Value for the maximum brightness. Default value for that
+			is 63.
+- label:		A label for the LED. If one is given, the LED will be
+			named "ubnt-spi:<label>" or "ubnt-spi::" otherwise.
+
+Being a SPI device this driver should be a sub-node of a SPI controller. The
+controller only supports one LED. For consistence with other controllers, the
+LED is defined as a sub-node.
+
+Example for the airCube ISP (with SPI controller matching that device):
+
+led_spi {
+	compatible = "spi-gpio";
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	gpio-sck = <&gpio 3 GPIO_ACTIVE_HIGH>;
+	gpio-mosi = <&gpio 2 GPIO_ACTIVE_HIGH>;
+	cs-gpios = <&gpio 1 GPIO_ACTIVE_HIGH>;
+	num-chipselects = <1>;
+
+	led_ubnt@0 {
+		compatible = "ubnt,spi-led";
+		reg = <0>;
+		spi-max-frequency = <100000>;
+
+		led {
+			label = "system";
+			/* keep the LED slightly on to show powered device */
+			ubnt-spi,off_bright = /bits/ 8 <4>;
+		};
+	};
+};
-- 
2.21.0