iio: max5481: Add support for Maxim digital potentiometers

Add implementation for Maxim Integrated 5481, 5482, 5483,
and 5484 digital potentiometer devices.

Datasheet:
http://datasheets.maximintegrated.com/en/ds/MAX5481-MAX5484.pdf

Signed-off-by: Maury Anderson <maury.anderson@rockwellcollins.com>
Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: Slawomir Stepien <sst@poczta.fm>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/iio/potentiometer/max5481.txt b/Documentation/devicetree/bindings/iio/potentiometer/max5481.txt
new file mode 100644
index 0000000..6a91b10
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/potentiometer/max5481.txt
@@ -0,0 +1,23 @@
+* Maxim Linear-Taper Digital Potentiometer MAX5481-MAX5484
+
+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:
+			"maxim,max5481"
+			"maxim,max5482"
+			"maxim,max5483"
+			"maxim,max5484"
+
+Example:
+max548x: max548x@0 {
+	compatible = "maxim,max5482";
+	spi-max-frequency = <7000000>;
+	reg = <0>; /* chip-select */
+};