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Date:      Tue, 4 Dec 2012 15:10:11 -0700
From:      Warner Losh <imp@bsdimp.com>
To:        Hiroki Sato <hrs@freebsd.org>
Cc:        freebsd-arch@FreeBSD.org, loos.br@gmail.com
Subject:   Re: FDT Support for GPIO (gpiobus and friends)
Message-ID:  <EC5C2FAF-43CC-43F3-A5D0-CDEF328252D3@bsdimp.com>
In-Reply-To: <20121205.060056.592894859995638978.hrs@allbsd.org>
References:  <BEB9A0F8-560B-4937-8707-653988A26D85@gmail.com> <20121205.060056.592894859995638978.hrs@allbsd.org>

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On Dec 4, 2012, at 2:00 PM, Hiroki Sato wrote:

> Luiz Otavio O Souza <loos.br@gmail.com> wrote
>  in <BEB9A0F8-560B-4937-8707-653988A26D85@gmail.com>:
> 
> lo> Hi,
> lo>
> lo> I've been playing with GPIO on RPi and found the missing support of
> lo> FDT on gpiobus very annoying.
> lo>
> lo> The following patch (gpio-fdt.diff) adds FDT support to GPIO (gpiobus,
> lo> gpioc, gpioled).
> lo>
> lo> The bcm2835_gpio.c.fdt.diff will add (a better) support of FDT on RPi
> lo> GPIO controller and the bcm2835.dts.diff has my changes on the RPi dts
> lo> for adding support of gpioled on 'ok' led (pin 16).
> lo>
> lo> Comments ?
> 
> I like this idea, but it should be consistent with standard device
> tree bindings.  For example,
> 
> +			gpiobus {
> +				compatible = "gpiobus";
> +
> +				/* Ok led */
> +				led {
> +					compatible = "gpioled";
> +					label = "ok";
> +					pins = <16>;
> +				};
> +			};

Yes.  This was the sort of thing that I didn't like...

> should be something like the following:
> 
> led {
> 	compatible = "gpio-leds";
> 	ok {
> 		gpios = <&foo 16 1>;
> 		label = "ok";
> 	};
> };
> 
> A node using GPIOs must have gpios property for the gpio-controller
> node and pin number.

Yes, this conforms much better with the  FTD standards.

Warner



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