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authorGuenter Roeck <linux@roeck-us.net>2013-02-07 21:09:00 +0400
committerJonathan Cameron <jic23@kernel.org>2013-03-16 14:17:59 +0400
commit17d82b47a215ded05ee3fb8d93b7c1269dbe0083 (patch)
tree9c97b48bad7e01d1450fa8e53a7cb4e688b3d41f /Documentation/devicetree/bindings/iio/iio-bindings.txt
parentcddc1424f39e7c04045a6431eaf13a003fb8335a (diff)
downloadlinux-17d82b47a215ded05ee3fb8d93b7c1269dbe0083.tar.xz
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>
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+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";
+ };