Re: [PATCH] gpio-keys: poll for release if GPIO cannot interrupt on both edges

[pHilipp Zabel <philipp.zabel@gmail.com>]

On Thu, Feb 5, 2009 at 5:38 PM, Guennadi Liakhovetski <lg@denx.de> wrote:
> There are GPIO controllers, that cannot be configured to produce
> interrupts on both edges. To be able to meaningfully use these for
> gpio-keys, add a polling option.

Are those controllers that can't even switch between rising/falling
edge detection? If you can switch, you can emulate both edge
triggering in the irqchip driver, like it is done for mfd/asic3.

>
> Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
> ---
>
> I previously tried to solve this problem by reporting a release event
> immediately after press, but this proved to be not very useful. This patch
> adds a timer to poll for release events on such buttons. I so far set the
> polling period to 50ms, don't know how good or bad this is, and whether we
> want to have it configurable.
>
> diff --git a/drivers/input/keyboard/gpio_keys.c b/drivers/input/keyboard/gpio_keys.c
> index ad67d76..2203fd0 100644
> --- a/drivers/input/keyboard/gpio_keys.c
> +++ b/drivers/input/keyboard/gpio_keys.c
> @@ -29,10 +29,13 @@ struct gpio_button_data {
>        struct gpio_keys_button *button;
>        struct input_dev *input;
>        struct timer_list timer;
> +       struct timer_list *release;
> +       int state;
>  };
>
>  struct gpio_keys_drvdata {
>        struct input_dev *input;
> +       struct timer_list release;
>        struct gpio_button_data data[0];
>  };
>
> @@ -43,10 +46,41 @@ static void gpio_keys_report_event(struct gpio_button_data *bdata)
>        unsigned int type = button->type ?: EV_KEY;
>        int state = (gpio_get_value(button->gpio) ? 1 : 0) ^ button->active_low;
>
> -       input_event(input, type, button->code, !!state);
> +       bdata->state = !!state;
> +       input_event(input, type, button->code, bdata->state);
> +       /* If the button only supports press events, poll for release */
> +       if (state && button->irq_trigger != (IRQF_TRIGGER_RISING |
> +                                            IRQF_TRIGGER_FALLING))
> +               mod_timer(bdata->release, jiffies + msecs_to_jiffies(50));
> +
>        input_sync(input);
>  }
>
> +static void gpio_poll_button(unsigned long _data)
> +{
> +       struct platform_device *pdev = (struct platform_device *)_data;
> +       struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
> +       struct gpio_keys_drvdata *ddata = platform_get_drvdata(pdev);
> +       int i;
> +
> +       for (i = 0; i < pdata->nbuttons; i++) {
> +               struct gpio_button_data *bdata = &ddata->data[i];
> +               struct gpio_keys_button *button = bdata->button;
> +
> +               if (bdata->state && button->irq_trigger !=
> +                   (IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING)) {
> +                       int state = (gpio_get_value(button->gpio) ? 1 : 0) ^
> +                               button->active_low;
> +
> +                       if (!state)
> +                               gpio_keys_report_event(bdata);
> +                       else
> +                               mod_timer(bdata->release, jiffies +
> +                                         msecs_to_jiffies(50));
> +               }
> +       }
> +}
> +
>  static void gpio_check_button(unsigned long _data)
>  {
>        struct gpio_button_data *data = (struct gpio_button_data *)_data;
> @@ -104,6 +138,9 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
>
>        ddata->input = input;
>
> +       setup_timer(&ddata->release,
> +                   gpio_poll_button, (unsigned long)pdev);
> +
>        for (i = 0; i < pdata->nbuttons; i++) {
>                struct gpio_keys_button *button = &pdata->buttons[i];
>                struct gpio_button_data *bdata = &ddata->data[i];
> @@ -141,9 +178,19 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
>                        goto fail2;
>                }
>
> +               button->irq_trigger &= IRQF_TRIGGER_RISING |
> +                       IRQF_TRIGGER_FALLING;
> +
> +               if (!button->irq_trigger)
> +                       button->irq_trigger = IRQF_TRIGGER_RISING |
> +                               IRQF_TRIGGER_FALLING;
> +
> +               if (button->irq_trigger != (IRQF_TRIGGER_RISING |
> +                                           IRQF_TRIGGER_FALLING))
> +                       bdata->release = &ddata->release;
> +
>                error = request_irq(irq, gpio_keys_isr,
> -                                   IRQF_SAMPLE_RANDOM | IRQF_TRIGGER_RISING |
> -                                       IRQF_TRIGGER_FALLING,
> +                                   IRQF_SAMPLE_RANDOM | button->irq_trigger,
>                                    button->desc ? button->desc : "gpio_keys",
>                                    bdata);
>                if (error) {
> @@ -171,6 +218,7 @@ static int __devinit gpio_keys_probe(struct platform_device *pdev)
>        return 0;
>
>  fail2:
> +       del_timer_sync(&ddata->release);
>        while (--i >= 0) {
>                free_irq(gpio_to_irq(pdata->buttons[i].gpio), &ddata->data[i]);
>                if (pdata->buttons[i].debounce_interval)
> @@ -195,6 +243,8 @@ static int __devexit gpio_keys_remove(struct platform_device *pdev)
>
>        device_init_wakeup(&pdev->dev, 0);
>
> +       del_timer_sync(&ddata->release);
> +
>        for (i = 0; i < pdata->nbuttons; i++) {
>                int irq = gpio_to_irq(pdata->buttons[i].gpio);
>                free_irq(irq, &ddata->data[i]);
> diff --git a/include/linux/gpio_keys.h b/include/linux/gpio_keys.h
> index 1289fa7..d0bd8e2 100644
> --- a/include/linux/gpio_keys.h
> +++ b/include/linux/gpio_keys.h
> @@ -10,6 +10,7 @@ struct gpio_keys_button {
>        int type;               /* input event type (EV_KEY, EV_SW) */
>        int wakeup;             /* configure the button as a wake-up source */
>        int debounce_interval;  /* debounce ticks interval in msecs */
> +       unsigned long irq_trigger; /* IRQF_TRIGGER_{RISING,FALLING} */
>  };
>
>  struct gpio_keys_platform_data {
> --
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regards
Philipp