[PATCH] drivers: create a pin control subsystem v8

[Linus Walleij]

On Mon, Oct 24, 2011 at 11:20 AM, Mike Frysinger <vapier.adi at gmail.com> wrote:

> but the question here is about pinctrl.  does userspace really need to
> manipulate the pinmapping ?  if we agree on that, then the question is
> on the userspace interface.
>
> assuming we want this, i can't see the performance argument being made
> here for pinctrl.  which means doing a sysfs interface here like we
> already have with GPIO makes the most sense.  GPIO deals in "binary"
> data for the most part (reading/writing 0/1 ints) so the string-based
> sysfs parsing is a bit weird, but pinctrl deals with strings
> everywhere for selecting mapping groups, so sysfs is the natural
> answer.

Hm now I feel I start to agree with you and come back to my
original proposition to do pinctrl in sysfs after all.

I wonder how soon we have a practical use case for this.
We do have this hacked-up driver in ux500:
http://git.linaro.org/gitweb?p=bsp/st-ericsson/linux-3.0-ux500.git;a=tree;f=drivers/staging/ab5500_sim;hb=HEAD

This controls a lot of SIM card pins from userspace...

Yours,
Linus Walleij