Re: [PATCH v1 6/7] mfd: lpc_ich: Add support for pinctrl in non-ACPI system

Andy Shevchenko
2021-04-12T17:34:55Z

On Mon, Apr 12, 2021 at 07:16:53PM +0200, Henning Schild wrote:
> Am Mon, 12 Apr 2021 19:59:05 +0300
> schrieb Andy Shevchenko <andriy.shevchenko@linux.intel.com>:
> > On Mon, Apr 12, 2021 at 06:40:01PM +0200, Henning Schild wrote:
> > > Tan or Andy,
> > >
> > > maybe you can point me to a user of that patch. I guess there might
> > > be an out-of-tree driver or userland code on how to use the GPIOs
> > > from there.
> >
> > I'm confused. User of this patch is pinctrl-broxton driver.
> > It's in upstream.
>
> Should this appear in /sys/class/gpio as chip so that pins can be
> exported?

No. Sysfs interface is deprecated. It should appear as /dev/gpiochip0 or so.

> That is what i tried and failed with.
>
> > Using GPIOs from it is something as done in a few drivers already
> > (Assuming we have no resources described in the ACPI). I.e. you need
> > to register in board file the GPIO mapping table with help of
> > devm_acpi_dev_add_driver_gpios() and use one of gpiod_get() family of
> > functions to request it.
> >
> > In case of LEDs you simple describe GPIO device name in lookup table
> > and that's it. The drivers/platform/x86/pcengines-apuv2.c not the
> > best but will give you an idea how to use "leds-gpio" driver in board
> > files.
>
> I am aware of that driver and had a look at it. In order to figure out
> the arguments for the macros/functions i was hoping for userland gpio
> "export", but maybe that does not work here ...
> For now i will assume that it does not show up in sysfs and can maybe
> still be used, and try to build on top.

Just switch to use libgpiod and associated tools / bindings in user space.
Sysfs ABI is not being developed anymore.

--
With Best Regards,
Andy Shevchenko