Re: [patch/rfc 2.6.25-git] gpio: sysfs interface

[Trent Piepho]

On Wed, 30 Apr 2008, Ben Nizette wrote:
> > On Tuesday 29 April 2008, Ben Nizette wrote:
> > > I guess one last option (which is made hard by chip label non-uniqueness
> > > but I'll throw out anyway) would be
> > >
> > > /sys/class/gpio
> > >         /chipa
> > >                 /gpio-n
> > >                         /value
> > >                         /direction
> > >                 /control
> > >         /chipb
> > >                 :
> > >                 :
> >
> > Or maybe:
> >
> >   /sys/class/gpio
> > 	/gpiochip-X			<-- range X..(X+ngpio)
> > 		/device			<-- symlink, if it's known
> > 		/ngpio
> > 		/label
> > 		/start			<-- maybe; start == X
> >
> > with the gpio-N links probably going where you showed.  That'd be
> > best in terms of Purity Of Essence.
>
> So you're suggesting that the gpio-N links and control file live inside
> the gpiochip-X folder along with info about the chip to which they're
> attached?  I don't mind this, sounds good.  Certainly feels most
> sysfsish.
>
> Scripting would be pretty simple assuming there's one control file per
> chip and the gpio number written to said control file is relative to
> that chip's base.  i.e. finding pcf9557:5 (assuming only one such
> device) would just be
>
> - find the gpiochip-X folder whose /label == pcf9557
> - echo "export 5" > <that_folder>/control
> - read/write <that_folder>/gpio-5/{value,direction}

I don't suppose you could actually write the code to do this?

I already wrote the code, and am using it, for the way I have it work.

cat /sys/class/gpio/pcf9557-0:5

But I guess this is too easy.  "We can't have any of that!!  The Earth will
turn in its grave!  And Slashdot will be decorated in Pink!  Teh End Daze
arrive!  :)"

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