From 0ac8eb6452e128abd7af08e5d4a38768833da0ca Mon Sep 17 00:00:00 2001 From: Peter Rosin Date: Fri, 8 Jul 2016 12:13:49 +0200 Subject: [PATCH] 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 Reviewed-by: Wolfram Sang Signed-off-by: Peter Rosin --- .../devicetree/bindings/i2c/i2c-gate.txt | 41 +++++++++++++++++++ MAINTAINERS | 1 + 2 files changed, 42 insertions(+) create mode 100644 Documentation/devicetree/bindings/i2c/i2c-gate.txt diff --git a/Documentation/devicetree/bindings/i2c/i2c-gate.txt b/Documentation/devicetree/bindings/i2c/i2c-gate.txt new file mode 100644 index 000000000000..1846d236e656 --- /dev/null +++ b/Documentation/devicetree/bindings/i2c/i2c-gate.txt @@ -0,0 +1,41 @@ +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>; + }; + }; + }; diff --git a/MAINTAINERS b/MAINTAINERS index cde3e729df2c..353bfe6bbaca 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -5668,6 +5668,7 @@ F: Documentation/i2c/i2c-topology F: Documentation/i2c/muxes/ F: Documentation/devicetree/bindings/i2c/i2c-mux* F: Documentation/devicetree/bindings/i2c/i2c-arb* +F: Documentation/devicetree/bindings/i2c/i2c-gate* F: drivers/i2c/i2c-mux.c F: drivers/i2c/muxes/ F: include/linux/i2c-mux.h -- 2.34.1