Re: [PATCH 5/6] gpio: ad7768: Add AD7768 GPIO auxiliary driver

[Linus Walleij <linusw@kernel.org>]

Hi Janani,

thanks for your patch!

On Thu, Jul 9, 2026 at 10:51 AM Janani Sunil <janani.sunil@analog.com> wrote:

> The AD7768/AD7768-4 ADC exposes 5 general-purpose I/O pins that can be
> independently configured as inputs or outputs. Add an auxiliary bus driver
> to expose these pins as a GPIO chip, registered by the parent IIO driver.
>
> The driver uses the parent's regmap for register access and delegates
> runtime power management to the parent device.
>
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>

(...)

When I look at these functions I see they are very close to something
the GPIO_REGMAP helpers should be able to do.

Bascically all that stops you from doing this is:

> +static int ad7768_gpio_direction_input(struct gpio_chip *chip,
> +                                      unsigned int offset)
> +{
> +       struct ad7768_gpio_state *st = gpiochip_get_data(chip);
> +
> +       PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->parent, pm);
> +       int ret = PM_RUNTIME_ACQUIRE_ERR(&pm);

These two things.

> +static int ad7768_gpio_get_direction(struct gpio_chip *chip,
> +                                    unsigned int offset)
> +{
> +       struct ad7768_gpio_state *st = gpiochip_get_data(chip);
> +       unsigned int val;
> +       int ret;
> +
> +       PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->parent, pm);
> +       ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
> +       if (ret)
> +               return ret;

Here again, etc.

Can't we just add a

struct device *pm_dev; to struct gpio_regmap_config, pass
st->parent there at init, modify drivers/gpio/gpio-regmap.c adding:

static int gpio_regmap_pm(struct gpio_regmap *gpio)
{
    PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(gpio->pm_device, pm);
    ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
    if (ret)
        return ret;
    return 0;
}

And call this in each of the standard callbacks so gpio-regmap.c
can handle PM as well for free? The above can be an ifdef stub if
runtime PM is not enabled.

Yours,
Linus Walleij