linux-kernel - Re: [PATCH v3 4/5] gpio: gpiolib: Add ngirq member to struct gpio_irq

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Message-ID: <CAMuHMdUiq3svPa+OMmG70HP-3h4gKV6puoT8QUm3WgPw+e4i=A@mail.gmail.com>
Date:   Thu, 12 May 2022 09:29:34 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Phil Edworthy <phil.edworthy@...esas.com>,
        Biju Das <biju.das.jz@...renesas.com>,
        Prabhakar <prabhakar.csengg@...il.com>
Subject: Re: [PATCH v3 4/5] gpio: gpiolib: Add ngirq member to struct gpio_irq_chip

Hi Prabhakar,

On Wed, May 11, 2022 at 8:32 PM Lad Prabhakar
<prabhakar.mahadev-lad.rj@...renesas.com> wrote:
> Supported GPIO IRQs by the chip is not always equal to the number of GPIO
> pins. For example on Renesas RZ/G2L SoC where it has GPIO0-122 pins but at
> a give point a maximum of only 32 GPIO pins can be used as IRQ lines in
> the IRQC domain.
>
> This patch adds ngirq member to struct gpio_irq_chip and passes this as a
> size to irq_domain_create_hierarchy()/irq_domain_create_simple() if it is
> being set in the driver otherwise fallbacks to using ngpio.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

Thanks for your patch!

> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1221,7 +1221,7 @@ static int gpiochip_hierarchy_add_domain(struct gpio_chip *gc)
>         gc->irq.domain = irq_domain_create_hierarchy(
>                 gc->irq.parent_domain,
>                 0,
> -               gc->ngpio,
> +               gc->irq.ngirq ?: gc->ngpio,
>                 gc->irq.fwnode,
>                 &gc->irq.child_irq_domain_ops,
>                 gc);
> @@ -1574,7 +1574,7 @@ static int gpiochip_add_irqchip(struct gpio_chip *gc,
>         } else {
>                 /* Some drivers provide custom irqdomain ops */
>                 gc->irq.domain = irq_domain_create_simple(fwnode,
> -                       gc->ngpio,
> +                       gc->irq.ngirq ?: gc->ngpio,
>                         gc->irq.first,
>                         gc->irq.domain_ops ?: &gpiochip_domain_ops,
>                         gc);

OK.

gpiochip_irqchip_remove() does:

        /* Remove all IRQ mappings and delete the domain */
        if (gc->irq.domain) {
                unsigned int irq;

                for (offset = 0; offset < gc->ngpio; offset++) {
                       if (!gpiochip_irqchip_irq_valid(gc, offset))

Hence it relies on gc->irq.valid_mask, which I think is OK in general.

                                continue;

                        irq = irq_find_mapping(gc->irq.domain, offset);
                        irq_dispose_mapping(irq);
                }

                irq_domain_remove(gc->irq.domain);

        }

> --- a/include/linux/gpio/driver.h
> +++ b/include/linux/gpio/driver.h
> @@ -51,6 +51,14 @@ struct gpio_irq_chip {
>          */
>         const struct irq_domain_ops *domain_ops;
>
> +       /**
> +        * @ngirq:
> +        *
> +        * The number of GPIO IRQ's handled by this IRQ domain; usually is
> +        * equal to ngpio.

"If not set, ngpio will be used."

> +        */
> +       u16 ngirq;
> +
>  #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
>         /**
>          * @fwnode:

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds