Subject: [PATCH RFC 1/2] gpio: Add a block GPIO API to gpiolib

From: [email-masked] (Roland Stigge)
Date: Sun, 30 Sep 2012 17:09:58 +0200

Hi Stijn,

On 30/09/12 16:52, Stijn Devriendt wrote:
>> One question: How did you solve the one-value-per-file in the sysfs
>> interface?
>>
> By exporting the group as a whole:
> /sys/.../gpiogroup248/value
> where value contains a decimal representing the group value.
> Again, this respects the ordering of the pins:
> 
> Actual pins: 0x2D (b 0010 1101)
> Selected pins: 6 3 0 1
> Readout: 6 (b 0 1 1 0)
> 
> The export sysfs file does, however, accept multiple gpio IDs for groups.
> Not sure if this is a 'violation' per se...

If I understand correctly, it's a violation (single-value should hold
for read and write).

To solve it, I have the following in mind: /sys/.../gpiogroupXXX/
contains files "bit0" ... "bit31" which contain a gpio number each,
empty if "unconnected".

Roland