Re: gpio-omap: add support gpiolib bias (pull-up/down) flags?

[Drew Fustini <drew@pdp7.com>]

On Wed, Apr 15, 2020 at 08:59:09AM -0500, Robert Nelson wrote:
> On Wed, Apr 15, 2020 at 8:47 AM Grygorii Strashko
> <grygorii.strashko@ti.com> wrote:
> > On 15/04/2020 16:20, Robert Nelson wrote:
> > > Hi Grygorii,
> > >
> > > On Wed, Apr 15, 2020 at 8:15 AM Grygorii Strashko
> > > <grygorii.strashko@ti.com> wrote:
> > >>
> > >> For this platforms the dynamic GPIO muxing/configuration is not supported, and GPIO block by itself
> > >> does not provide such functions as pullup/pulldown.
> > >
> > > Correct, that's the state today, while Drew is investing time into
> > > trying to figure out how to properly extend this feature into our
> > > platform.
> >
> > Sry, but it's not clear what's the final target (at least from public part of this thread).
> 
> We are mainly targeting am335x based devices.  Today (well last few
> years) we've utilized a "hack-ish" kernel module (bone-pinmux-helper)
> to allow users to overide/change the pinmux-ing directly from
> user-space...  (This evil module allows us to specify a list of
> options for each pin, thus users can easily configure specifies of the
> pin, aka gpio_pd/gpio_pu/etc from user-space...).  Since that time,
> mainline has now grown a generic gpio pull-up/pull-down functionality,
> with the ability to re-control these values directly from a generic
> gpio library (libgpiod).

Hello Grygorii -

As Robert described, I wanted to make us of the new support for bias
flags in the gpiolib uapi which allows userspace libraries like libgpiod
set pull-up or pull-down on lines [0].

Is there no way for gpio-omap to call into the pinctrl-single backend to
set the bias bits (PULLUDEN and PULLTYPESEL) in pad control registers?

Thank you,
Drew

[0] https://lore.kernel.org/linux-gpio/20191105020429.18942-1-warthog618@gmail.com/