[PATCH v3 03/10] gpiolib: implement low-level, shared GPIO support

[Bartosz Golaszewski]

On Wed, Oct 29, 2025 at 12:45 PM Andy Shevchenko
<andriy.shevchenko at intel.com> wrote:
>
> On Wed, Oct 29, 2025 at 12:20:39PM +0100, Bartosz Golaszewski wrote:
> >
> > This module scans the device tree (for now only OF nodes are supported
> > but care is taken to make other fwnode implementations easy to
> > integrate) and determines which GPIO lines are shared by multiple users.
> > It stores that information in memory. When the GPIO chip exposing shared
> > lines is registered, the shared GPIO descriptors it exposes are marked
> > as shared and virtual "proxy" devices that mediate access to the shared
> > lines are created. When a consumer of a shared GPIO looks it up, its
> > fwnode lookup is redirected to a just-in-time machine lookup that points
> > to this proxy device.
> >
> > This code can be compiled out on platforms which don't use shared GPIOs.
>
> Besides strcmp_suffix() that already exists in OF core, there are also some
> existing pieces that seems being repeated here (again). Can we reduce amount
> of duplication?
>

I'm afraid you need to be more specific here.

> ...
>
> > +#if IS_ENABLED(CONFIG_OF)
> > +static int gpio_shared_of_traverse(struct device_node *curr)
> > +{
>
> I believe parts of this code may be resided somewhere in drivers/of/property.c
> or nearby as it has the similar parsing routines.
>

I don't think this is a good idea, I want to keep it within the
confines of drivers/gpio/ and the use-case is so specific, there's
really no point in putting parts of it under drivers/of/.

If I could only iterate over all properties of an fwnode, I'd have
skipped using OF-specific routines altogether.

Bart