[v5,3/5] gpio: gpiolib: Allow free() callback to be overridden

Allow free() callback to be overridden from irq_domain_ops for
hierarchical chips.

This allows drivers to free up resources which are allocated during
child_to_parent_hwirq()/populate_parent_alloc_arg() callbacks.

On Renesas RZ/G2L platform a bitmap is maintained for TINT slots, a slot
is allocated in child_to_parent_hwirq() callback which is freed up in free
callback hence this override.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/gpio/gpiolib.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Hi Linus,

Thank you for the feedback.

On Tue, May 24, 2022 at 9:54 AM Linus Walleij <linus.walleij@linaro.org> wrote:
>
> On Mon, May 23, 2022 at 7:43 PM Lad Prabhakar
> <prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
>
> > Allow free() callback to be overridden from irq_domain_ops for
> > hierarchical chips.
> >
> > This allows drivers to free up resources which are allocated during
> > child_to_parent_hwirq()/populate_parent_alloc_arg() callbacks.
> >
> > On Renesas RZ/G2L platform a bitmap is maintained for TINT slots, a slot
> > is allocated in child_to_parent_hwirq() callback which is freed up in free
> > callback hence this override.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
>
> So that function today looks like this:
>
> static void gpiochip_hierarchy_setup_domain_ops(struct irq_domain_ops *ops)
> {
>         ops->activate = gpiochip_irq_domain_activate;
>         ops->deactivate = gpiochip_irq_domain_deactivate;
>         ops->alloc = gpiochip_hierarchy_irq_domain_alloc;
>         ops->free = irq_domain_free_irqs_common;
>
>         /*
>          * We only allow overriding the translate() function for
>          * hierarchical chips, and this should only be done if the user
>          * really need something other than 1:1 translation.
>          */
>         if (!ops->translate)
>                 ops->translate = gpiochip_hierarchy_irq_domain_translate;
> }
>
> (...)
> -       ops->free = irq_domain_free_irqs_common;
> (...)
> > +       if (!ops->free)
> > +               ops->free = irq_domain_free_irqs_common;
>
> Marc Z is working on cleaning up the way that gpiolib is (ab)using
> irqchips. We definitely need his ACK if we do things like this.
> This doesn't look like one of the big offenders to me, but I want
> to make sure we don't create new problems while Marc is trying
> to solve the old ones.
>
Agreed, I had a discussion with Marc on v3 series [0].

[0] https://patchwork.kernel.org/project/linux-renesas-soc/patch/20220511183210.5248-4-prabhakar.mahadev-lad.rj@bp.renesas.com/

Cheers,
Prabhakar

On Tue, May 24, 2022 at 11:07 AM Lad, Prabhakar
<prabhakar.csengg@gmail.com> wrote:
> On Tue, May 24, 2022 at 9:54 AM Linus Walleij <linus.walleij@linaro.org> wrote:
> >
> > On Mon, May 23, 2022 at 7:43 PM Lad Prabhakar
> > <prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> >
> > > Allow free() callback to be overridden from irq_domain_ops for
> > > hierarchical chips.
> > >
> > > This allows drivers to free up resources which are allocated during
> > > child_to_parent_hwirq()/populate_parent_alloc_arg() callbacks.
> > >
> > > On Renesas RZ/G2L platform a bitmap is maintained for TINT slots, a slot
> > > is allocated in child_to_parent_hwirq() callback which is freed up in free
> > > callback hence this override.
> > >
> > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > > Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
> >
> > So that function today looks like this:
> >
> > static void gpiochip_hierarchy_setup_domain_ops(struct irq_domain_ops *ops)
> > {
> >         ops->activate = gpiochip_irq_domain_activate;
> >         ops->deactivate = gpiochip_irq_domain_deactivate;
> >         ops->alloc = gpiochip_hierarchy_irq_domain_alloc;
> >         ops->free = irq_domain_free_irqs_common;
> >
> >         /*
> >          * We only allow overriding the translate() function for
> >          * hierarchical chips, and this should only be done if the user
> >          * really need something other than 1:1 translation.
> >          */
> >         if (!ops->translate)
> >                 ops->translate = gpiochip_hierarchy_irq_domain_translate;
> > }
> >
> > (...)
> > -       ops->free = irq_domain_free_irqs_common;
> > (...)
> > > +       if (!ops->free)
> > > +               ops->free = irq_domain_free_irqs_common;
> >
> > Marc Z is working on cleaning up the way that gpiolib is (ab)using
> > irqchips. We definitely need his ACK if we do things like this.
> > This doesn't look like one of the big offenders to me, but I want
> > to make sure we don't create new problems while Marc is trying
> > to solve the old ones.
> >
> Agreed, I had a discussion with Marc on v3 series [0].

Hm yeah I guess I am just stepping on Marc's toes with all my mails :(

I'll try to just wait for Marc's Reviewed-by instead and not add to the noise,
I'm probably just wrong.

Yours,
Linus Walleij