Re: [PATCH 0/6] GPIO character device skeleton

[Amit Kucheria <amit.kucheria@xxxxxxxxxx>]

On Tue, Nov 3, 2015 at 2:20 PM, Mark Brown <broonie@xxxxxxxxxx> wrote:
> On Tue, Nov 03, 2015 at 08:39:13AM +0100, Markus Pargmann wrote:
>
>> I think we need real gpio userspace tools for such a chardev interface and not
>> only a library. On the one hand there are all the kernel/userspace developers
>> that just want to test stuff. On the other hand there are really a lot of
>> people that are using small embedded devices (e.g. beaglebone, raspberry pi,
>> ...) for really simple applications like using GPIOs to control something. I am
>> sure many of them are just using some really simple bash code to reach their
>> goals.
>
> There's already some work going on on producing tooling for the maker
> community which is currently working with the existing interfaces,
> attempting to abstract them for users to handle things like base board
> differences - I believe that's part of the motivation behind this work.

Here is an example[1] of the kind of workarounds needed to get a
consistent userspace programming interface by mapping SoC-specific
gpios to fixed gpio names on the expansion connector of a 96board.

Ideally, the kernel would allow us to do this through some DT properties.

Regards,
Amit

[1] https://github.com/96boards/96BoardsGPIO/blob/a17e58867ecfeba36d163580bc1839ffdbca8cca/lib/__gpio.h
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