Commit 0ac8eb64 authored by Peter Rosin's avatar Peter Rosin
Browse files

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: default avatarRob Herring <robh@kernel.org>
Reviewed-by: default avatarWolfram Sang <wsa@the-dreams.de>
Signed-off-by: default avatarPeter Rosin <peda@axentia.se>
parent e8813c15

Documentation/devicetree/bindings/i2c/i2c-gate.txt

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Original line number Diff line number Diff line 
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>;

			};

		};

	};

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -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

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