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authorPeter Rosin <peda@axentia.se>2016-07-08 13:13:49 +0300
committerPeter Rosin <peda@axentia.se>2016-08-25 23:11:01 +0300
commit0ac8eb6452e128abd7af08e5d4a38768833da0ca (patch)
tree7488c1c165fdc8fcd747280e8e706858b2af32fc /Documentation/devicetree/bindings/i2c
parente8813c15be0a9e7f2c79c58d3329d92bcf056ecc (diff)
downloadlinux-0ac8eb6452e128abd7af08e5d4a38768833da0ca.tar.xz
dt-bindings: i2c: add support for 'i2c-gate' subnode
Handle i2c gates similarly to how i2c arbitrators are handled. This gets rid of a pointless 'reg' property for i2c gates. I.e. this new and more compact style some-gate { i2c-gate { #address-cells = <1>; #size-cells = <0>; some-i2c-device@50 { reg = <0x50>; }; }; }; instead of the old some-gate { #address-cells = <1>; #size-cells = <0>; i2c@0 { reg = <0>; #address-cells = <1>; #size-cells = <0>; some-i2c-device@50 { reg = <0x50>; }; }; }; Acked-by: Rob Herring <robh@kernel.org> Reviewed-by: Wolfram Sang <wsa@the-dreams.de> Signed-off-by: Peter Rosin <peda@axentia.se>
Diffstat (limited to 'Documentation/devicetree/bindings/i2c')
-rw-r--r--Documentation/devicetree/bindings/i2c/i2c-gate.txt41
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diff --git a/Documentation/devicetree/bindings/i2c/i2c-gate.txt b/Documentation/devicetree/bindings/i2c/i2c-gate.txt
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+An i2c gate is useful to e.g. reduce the digital noise for RF tuners connected
+to the i2c bus. Gates are similar to arbitrators in that you need to perform
+some kind of operation to access the i2c bus past the arbitrator/gate, but
+there are no competing masters to consider for gates and therefore there is
+no arbitration happening for gates.
+
+Common i2c gate properties.
+
+- i2c-gate child node
+
+Required properties for the i2c-gate child node:
+- #address-cells = <1>;
+- #size-cells = <0>;
+
+Optional properties for i2c-gate child node:
+- Child nodes conforming to i2c bus binding
+
+
+Example :
+
+ /*
+ An Invensense mpu9150 at address 0x68 featuring an on-chip Asahi
+ Kasei ak8975 compass behind a gate.
+ */
+
+ mpu9150@68 {
+ compatible = "invensense,mpu9150";
+ reg = <0x68>;
+ interrupt-parent = <&gpio1>;
+ interrupts = <18 1>;
+
+ i2c-gate {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ ax8975@c {
+ compatible = "ak,ak8975";
+ reg = <0x0c>;
+ };
+ };
+ };