iio: Add OF support

Provide bindings and parse OF data during initialization.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

1 files changed, 97 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/iio/iio-bindings.txt b/Documentation/devicetree/bindings/iio/iio-bindings.txt
new file mode 100644
index 000000000000..0b447d9ad196
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/iio-bindings.txt
@@ -0,0 +1,97 @@
+This binding is derived from clock bindings, and based on suggestions
+from Lars-Peter Clausen [1].
+
+Sources of IIO channels can be represented by any node in the device
+tree. Those nodes are designated as IIO providers. IIO consumer
+nodes use a phandle and IIO specifier pair to connect IIO provider
+outputs to IIO inputs. Similar to the gpio specifiers, an IIO
+specifier is an array of one or more cells identifying the IIO
+output on a device. The length of an IIO specifier is defined by the
+value of a #io-channel-cells property in the IIO provider node.
+
+[1] http://marc.info/?l=linux-iio&m=135902119507483&w=2
+
+==IIO providers==
+
+Required properties:
+#io-channel-cells: Number of cells in an IIO specifier; Typically 0 for nodes
+		   with a single IIO output and 1 for nodes with multiple
+		   IIO outputs.
+
+Example for a simple configuration with no trigger:
+
+	adc: voltage-sensor@35 {
+		compatible = "maxim,max1139";
+		reg = <0x35>;
+		#io-channel-cells = <1>;
+	};
+
+Example for a configuration with trigger:
+
+	adc@35 {
+		compatible = "some-vendor,some-adc";
+		reg = <0x35>;
+
+		adc1: iio-device@0 {
+			#io-channel-cells = <1>;
+			/* other properties */
+		};
+		adc2: iio-device@1 {
+			#io-channel-cells = <1>;
+			/* other properties */
+		};
+	};
+
+==IIO consumers==
+
+Required properties:
+io-channels:	List of phandle and IIO specifier pairs, one pair
+		for each IIO input to the device. Note: if the
+		IIO provider specifies '0' for #io-channel-cells,
+		then only the phandle portion of the pair will appear.
+
+Optional properties:
+io-channel-names:
+		List of IIO input name strings sorted in the same
+		order as the io-channels property. Consumers drivers
+		will use io-channel-names to match IIO input names
+		with IIO specifiers.
+io-channel-ranges:
+		Empty property indicating that child nodes can inherit named
+		IIO channels from this node. Useful for bus nodes to provide
+		and IIO channel to their children.
+
+For example:
+
+	device {
+		io-channels = <&adc 1>, <&ref 0>;
+		io-channel-names = "vcc", "vdd";
+	};
+
+This represents a device with two IIO inputs, named "vcc" and "vdd".
+The vcc channel is connected to output 1 of the &adc device, and the
+vdd channel is connected to output 0 of the &ref device.
+
+==Example==
+
+	adc: max1139@35 {
+		compatible = "maxim,max1139";
+		reg = <0x35>;
+		#io-channel-cells = <1>;
+	};
+
+	...
+
+	iio_hwmon {
+		compatible = "iio-hwmon";
+		io-channels = <&adc 0>, <&adc 1>, <&adc 2>,
+			<&adc 3>, <&adc 4>, <&adc 5>,
+			<&adc 6>, <&adc 7>, <&adc 8>,
+			<&adc 9>;
+	};
+
+	some_consumer {
+		compatible = "some-consumer";
+		io-channels = <&adc 10>, <&adc 11>;
+		io-channel-names = "adc1", "adc2";
+	};