dt-bindings: iio: potentiometer: Add Microchip MCP41xxx/42xxx

This patch adds device tree documentation for the Microchip
MCP41xxx/42xxx family of digital potentiometers.

Signed-off-by: Chris Coffey <cmc@babblebit.net>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt b/Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt
new file mode 100644 (file)
index 0000000..566711b
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/potentiometer/mcp41010.txt
@@ -0,0 +1,28 @@
+* Microchip MCP41010/41050/41100/42010/42050/42100 Digital Potentiometer
+
+Datasheet publicly available at:
+http://ww1.microchip.com/downloads/en/devicedoc/11195c.pdf
+
+The node for this driver must be a child node of a SPI controller, hence
+all mandatory properties described in
+
+        Documentation/devicetree/bindings/spi/spi-bus.txt
+
+must be specified.
+
+Required properties:
+       - compatible:   Must be one of the following, depending on the
+                       model:
+                       "microchip,mcp41010"
+                       "microchip,mcp41050"
+                       "microchip,mcp41100"
+                       "microchip,mcp42010"
+                       "microchip,mcp42050"
+                       "microchip,mcp42100"
+
+Example:
+potentiometer@0 {
+       compatible = "microchip,mcp41010";
+       reg = <0>;
+       spi-max-frequency = <500000>;
+};