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Date: Thu, 5 Feb 2009 17:44:31 +0100
From: pHilipp Zabel <philipp.zabel@...il.com>
To: Guennadi Liakhovetski <lg@...x.de>
Cc: linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
dmitry.torokhov@...il.com
Subject: Re: [PATCH] gpio-keys: poll for release if GPIO cannot interrupt on
both edges
On Thu, Feb 5, 2009 at 5:38 PM, Guennadi Liakhovetski <lg@...x.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@...x.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
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