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Commit e8813c15 authored by Peter Rosin's avatar Peter Rosin
Browse files

dt-bindings: i2c: add support for 'i2c-arb' subnode 



This gets rid of the need for a pointless 'reg' property for i2c
arbitrators.

I.e. this new and more compact style

	some-arbitrator {
		i2c-arb {
			#address-cells = <1>;
			#size-cells = <0>;

			some-i2c-device@50 {
				reg = <0x50>;
			};
		};
	};

instead of the old

	some-arbitrator {
		#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 374f8436

Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt

+2 −6
Original line number Diff line number Diff line
@@ -44,8 +44,7 @@ Required properties: 
- our-claim-gpio: The GPIO that we use to claim the bus.

- their-claim-gpios: The GPIOs that the other sides use to claim the bus.

  Note that some implementations may only support a single other master.

- Standard I2C mux properties. See i2c-mux.txt in this directory.

- Single I2C child bus node at reg 0. See i2c-mux.txt in this directory.

- I2C arbitration bus node. See i2c-arb.txt in this directory.



Optional properties:

- slew-delay-us: microseconds to wait for a GPIO to go high. Default is 10 us.
@@ -63,8 +62,6 @@ Example: 


	i2c-arbitrator {

		compatible = "i2c-arb-gpio-challenge";

		#address-cells = <1>;

		#size-cells = <0>;



		i2c-parent = <&{/i2c@12CA0000}>;
@@ -74,8 +71,7 @@ Example: 
		wait-retry-us = <3000>;

		wait-free-us = <50000>;



		i2c@0 {

			reg = <0>;

		i2c-arb {

			#address-cells = <1>;

			#size-cells = <0>;

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

0 → 100644
+35 −0
Original line number Diff line number Diff line 
Common i2c arbitration bus properties.



- i2c-arb child node



Required properties for the i2c-arb child node:

- #address-cells = <1>;

- #size-cells = <0>;



Optional properties for i2c-arb child node:

- Child nodes conforming to i2c bus binding





Example :



	/*

	   An NXP pca9541 I2C bus master selector at address 0x74

	   with a NXP pca8574 GPIO expander attached.

	 */



	arb@74 {

		compatible = "nxp,pca9541";

		reg = <0x74>;



		i2c-arb {

			#address-cells = <1>;

			#size-cells = <0>;



			gpio@38 {

				compatible = "nxp,pca8574";

				reg = <0x38>;

				#gpio-cells = <2>;

				gpio-controller;

			};

		};

	};

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -5667,6 +5667,7 @@ S: Maintained 
F:	Documentation/i2c/i2c-topology

F:	Documentation/i2c/muxes/

F:	Documentation/devicetree/bindings/i2c/i2c-mux*

F:	Documentation/devicetree/bindings/i2c/i2c-arb*

F:	drivers/i2c/i2c-mux.c

F:	drivers/i2c/muxes/

F:	include/linux/i2c-mux.h