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

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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: Rob Herring <robh@kernel.org>
Reviewed-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Peter Rosin <peda@axentia.se>
This commit is contained in:
Peter Rosin 2016-07-08 12:12:17 +02:00
parent 374f8436ff
commit e8813c15be
3 changed files with 38 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
Documentation/devicetree/bindings/i2c/i2c-arb-gpio-challenge.txt
View File

@ -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>;

35
Documentation/devicetree/bindings/i2c/i2c-arb.txt Normal file
View File

@ -0,0 +1,35 @@
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;
};
};
};

1
MAINTAINERS
View File

@ -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