Re: [PATCH v3] gpio: add export with name from dts

[Ben Gamari <bgamari.foss@gmail.com>]

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Linus Walleij wrote,
> I think what Mark is saying is that you should not define a new node
> for exports, but instead use the node for the gpiochip and extend
> those existing gpiochip bindings, if you want to do this.
>
What might this look like? Should each exported pin have a node under
the gpio-controller? If we want to allow for pins to be exported to
userspace, a name alone is not sufficient; we also need to provide the
allowed directions. I think this precludes the use of a plain /aliases
node.

Perhaps something like this (please excuse my ignorance of devicetree
norms)?

	gpio1: gpio-controller@1400 {
		#gpio-cells = <2>;
		compatible = "fsl,qe-pario-bank-a", "fsl,qe-pario-bank";
		reg = <0x1400 0x18>;
		gpio-controller;

                pin_a: gpio {
                          gpio-name = "pin-a";
                          gpio = <&gpio1 2 0>;
                          output;
                          init-high;
                };
	};

One issue with this is the redundancy of specifying both the
gpio-controller in the `gpio` attribute and by virtue of it being a
child of the controller. Other suggestions?

Cheers,

- Ben

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