linux-kernel - Re: [PATCH 2/2] gpiolib: support parsing gpio three-cell interrupts scheme

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Message-ID: <CACRpkdZ1X5kF-AyRBg9BYMiJscv0v-SGzcdetS0XDK3oPSu9QQ@mail.gmail.com>
Date: Fri, 28 Feb 2025 10:11:56 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Yixun Lan <dlan@...too.org>
Cc: Bartosz Golaszewski <brgl@...ev.pl>, Thomas Gleixner <tglx@...utronix.de>, Alex Elder <elder@...cstar.com>, 
	Inochi Amaoto <inochiama@...il.com>, linux-kernel@...r.kernel.org, 
	linux-gpio@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	spacemit@...ts.linux.dev
Subject: Re: [PATCH 2/2] gpiolib: support parsing gpio three-cell interrupts scheme

Hi Yixun,

thanks for working so hard on this!

I'm really happy to see the threecell support integrated into gpiolib.

On Thu, Feb 27, 2025 at 12:25 PM Yixun Lan <dlan@...too.org> wrote:

> gpio irq which using three-cell scheme should always call
> instance_match() function to find the correct irqdomain.
>
> Signed-off-by: Yixun Lan <dlan@...too.org>
> ---
> The select() function will be called with !DOMAIN_BUS_ANY,
> kernel/irq/irqdomain.c:556: if (h->ops->select && bus_token != DOMAIN_BUS_ANY)
>
> so vendor gpio driver need to explicitly set bus_token, something like:
>
> drivers/gpio/gpio-spacemit-k1.c
>   irq_domain_update_bus_token(girq->domain, DOMAIN_BUS_WIRED);
>
> I hope this is a feasible way..

Yes this looks fair, I think you can put the description into the
commit message.

>         /* We support standard DT translation */
> -       if (is_of_node(fwspec->fwnode) && fwspec->param_count == 2) {
> +       if (is_of_node(fwspec->fwnode) && fwspec->param_count <= 3)
>                 return irq_domain_translate_twocell(d, fwspec, hwirq, type);
> -       }

This looks good.

> +static int gpiochip_irq_select(struct irq_domain *d, struct irq_fwspec *fwspec,
> +                       enum irq_domain_bus_token bus_token)
> +{
> +       struct fwnode_handle *fwnode = fwspec->fwnode;
> +       struct gpio_chip *gc = d->host_data;
> +       unsigned int index = fwspec->param[0];
> +
> +       if ((gc->of_gpio_n_cells == 3) && gc->of_node_instance_match)
> +               return gc->of_node_instance_match(gc, index);

We need to hide the OF-specific things into gpiolib-of.c|h so systems
not using OF does not need to see it.

Something like:

if (fwspec->param_count == 3) {
     if (is_of_node(fwnode))
         return of_gpiochip_instance_match(gc, index);
    /* Add other threeparam handlers here */
}

Then add of_gpiochip_instance_match() into gpiolib-of.h as a
static inline (no need to an entire extern function...)

static inline bool of_gpiochip_instance_match(struct gpio_chip *gc, int index)
{
    if ((gc->of_gpio_n_cells == 3) && gc->of_node_instance_match)
              return gc->of_node_instance_match(gc, index);
}

And also an empty stub for !CONFIG_OF_GPIO so we get this compiled
out if OF is not configured in.

Yours,
Linus Walleij