linux-kernel - Re: [PATCH resend] gpio: aggregator: Add interrupt support

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Date:   Fri, 3 Dec 2021 15:56:01 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Enrico Weigelt metux IT consult <info@...ux.net>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Arnd Bergmann <arnd@...nel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        virtualization@...ts.linux-foundation.org,
        stratos-dev@...lists.linaro.org
Subject: Re: [PATCH resend] gpio: aggregator: Add interrupt support

On Fri, Dec 3, 2021 at 3:06 PM Geert Uytterhoeven
<geert+renesas@...der.be> wrote:
>
> Currently the GPIO Aggregator does not support interrupts.  This means
> that kernel drivers going from a GPIO to an IRQ using gpiod_to_irq(),
> and userspace applications using line events do not work.
>
> Add interrupt support by providing a gpio_chip.to_irq() callback, which
> just calls into the parent GPIO controller.
>
> Note that this does not implement full interrupt controller (irq_chip)
> support, so using e.g. gpio-keys with "interrupts" instead of "gpios"
> still does not work.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> I would prefer to avoid implementing irq_chip support, until there is a
> real use case for this.
>
> This has been tested with gpio-keys and gpiomon on the Koelsch
> development board:
>
>   - gpio-keys, using a DT overlay[1]:
>
>         $ overlay add r8a7791-koelsch-keyboard-controlled-led
>         $ echo gpio-aggregator > /sys/devices/platform/frobnicator/driver_override
>         $ echo frobnicator > /sys/bus/platform/drivers/gpio-aggregator/bind
>
>         $ gpioinfo frobnicator
>         gpiochip12 - 3 lines:
>                 line   0:      "light"      "light"  output  active-high [used]
>                 line   1:         "on"         "On"   input   active-low [used]
>                 line   2:        "off"        "Off"   input   active-low [used]
>
>         $ echo 255 > /sys/class/leds/light/brightness
>         $ echo 0 > /sys/class/leds/light/brightness
>
>         $ evtest /dev/input/event0
>
>   - gpiomon, using the GPIO sysfs API:
>
>         $ echo keyboard > /sys/bus/platform/drivers/gpio-keys/unbind
>         $ echo e6055800.gpio 2,6 > /sys/bus/platform/drivers/gpio-aggregator/new_device
>         $ gpiomon gpiochip12 0 1
>
> [1] "ARM: dts: koelsch: Add overlay for keyboard-controlled LED"
>     https://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git/commit/?h=topic/renesas-overlays&id=c78d817869e63a3485bb4ab98aeea6ce368a396e
> ---
>  drivers/gpio/gpio-aggregator.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-aggregator.c b/drivers/gpio/gpio-aggregator.c
> index e9671d1660ef4b40..869dc952cf45218b 100644
> --- a/drivers/gpio/gpio-aggregator.c
> +++ b/drivers/gpio/gpio-aggregator.c
> @@ -371,6 +371,13 @@ static int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset,
>         return gpiod_set_config(fwd->descs[offset], config);
>  }
>
> +static int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset)
> +{
> +       struct gpiochip_fwd *fwd = gpiochip_get_data(chip);
> +
> +       return gpiod_to_irq(fwd->descs[offset]);
> +}
> +
>  /**
>   * gpiochip_fwd_create() - Create a new GPIO forwarder
>   * @dev: Parent device pointer
> @@ -411,7 +418,8 @@ static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
>         for (i = 0; i < ngpios; i++) {
>                 struct gpio_chip *parent = gpiod_to_chip(descs[i]);
>
> -               dev_dbg(dev, "%u => gpio-%d\n", i, desc_to_gpio(descs[i]));
> +               dev_dbg(dev, "%u => gpio %d irq %d\n", i,
> +                       desc_to_gpio(descs[i]), gpiod_to_irq(descs[i]));
>
>                 if (gpiod_cansleep(descs[i]))
>                         chip->can_sleep = true;
> @@ -429,6 +437,7 @@ static struct gpiochip_fwd *gpiochip_fwd_create(struct device *dev,
>         chip->get_multiple = gpio_fwd_get_multiple_locked;
>         chip->set = gpio_fwd_set;
>         chip->set_multiple = gpio_fwd_set_multiple_locked;
> +       chip->to_irq = gpio_fwd_to_irq;
>         chip->base = -1;
>         chip->ngpio = ngpios;
>         fwd->descs = descs;
> --
> 2.25.1
>

Applied, thanks!

Bart