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Date: Thu, 23 Oct 2014 10:44:05 +0200
From: Frans Klaver <frans.klaver@...ns.com>
To: Sebastian Reichel <sre@...nel.org>
CC: Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
David Woodhouse <dwmw2@...radead.org>,
Grant Likely <grant.likely@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
René Moll <linux@...oll.nl>,
Guenter Roeck <linux@...ck-us.net>,
<linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>,
<devicetree@...r.kernel.org>
Subject: Re: [PATCH 12/13] power: reset: ltc2952: make trigger input optional
On Wed, Oct 22, 2014 at 04:31:09PM +0200, Frans Klaver wrote:
> Currently the ltc2952 supports only one button sequence to initiate
> powerdown. This is not always desirable, as even prolonged button
> presses can happen in use.
>
> Allow ltc2952 users to pick their own power down sequence, by making the
> trigger input optional. Since this still means that the ltc2952 may
> power down the platform if the power button is pressed for about 5
> seconds, we still need to make sure to start the watchdog toggle to
> prolong the system power for as long as we need it.
>
> This will still allow the system to control power using the kill signal.
>
> Signed-off-by: Frans Klaver <frans.klaver@...ns.com>
> ---
> drivers/power/reset/ltc2952-poweroff.c | 87 +++++++++++++++++++++-------------
> 1 file changed, 55 insertions(+), 32 deletions(-)
>
> diff --git a/drivers/power/reset/ltc2952-poweroff.c b/drivers/power/reset/ltc2952-poweroff.c
> index fda2735..72e3d7f 100644
> --- a/drivers/power/reset/ltc2952-poweroff.c
> +++ b/drivers/power/reset/ltc2952-poweroff.c
> @@ -32,7 +32,9 @@
> * - trigger (input)
> * A level change indicates the shut-down trigger. If it's state reverts
> * within the time-out defined by trigger_delay, the shut down is not
> - * executed.
> + * executed. If no pin is assigned to this input, the driver will start the
> + * watchdog toggle immediately. The chip will only power off the system if
> + * it is requested to do so through the kill line.
> *
> * - watchdog (output)
> * Once a shut down is triggered, the driver will toggle this signal,
> @@ -116,15 +118,10 @@ static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)
> return HRTIMER_RESTART;
> }
>
> -static enum hrtimer_restart
> -ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
> +static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
> {
> - struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);
> - int ret = hrtimer_start(&data->timer_wde,
> - data->wde_interval, HRTIMER_MODE_REL);
> -
> - if (ret) {
> - dev_err(data->dev, "unable to start the timer\n");
> + if (hrtimer_start(&data->timer_wde, data->wde_interval,
> + HRTIMER_MODE_REL)) {
> /*
> * The device will not toggle the watchdog reset,
> * thus shut down is only safe if the PowerPath controller
> @@ -133,10 +130,17 @@ ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
> *
> * Only sending a warning as the system will power-off anyway
> */
> + dev_err(data->dev, "unable to start the timer\n");
> }
> +}
>
> - dev_info(data->dev, "executing shutdown\n");
> +static enum hrtimer_restart
> +ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
> +{
> + struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);
>
> + ltc2952_poweroff_start_wde(data);
> + dev_info(data->dev, "executing shutdown\n");
> orderly_poweroff(true);
>
> return HRTIMER_NORESTART;
> @@ -190,7 +194,7 @@ static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
>
> static int ltc2952_poweroff_init(struct platform_device *pdev)
> {
> - int ret, virq;
> + int ret;
> struct ltc2952_poweroff *data = platform_get_drvdata(pdev);
>
> ltc2952_poweroff_default(data);
> @@ -210,29 +214,48 @@ static int ltc2952_poweroff_init(struct platform_device *pdev)
> return ret;
> }
>
> - data->gpio_trigger = devm_gpiod_get(&pdev->dev, "trigger",
> - GPIOD_IN);
> - if (IS_ERR(ltc2952_data->gpio_trigger)) {
> - ret = PTR_ERR(ltc2952_data->gpio_trigger);
> - dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n");
> - return ret;
> - }
> -
> - virq = gpiod_to_irq(data->gpio_trigger);
> - if (virq < 0) {
> - dev_err(&pdev->dev, "cannot map GPIO as interrupt");
> - return ret;
> + data->gpio_trigger = devm_gpiod_get(&pdev->dev, "trigger", GPIOD_IN);
> + if (IS_ERR(data->gpio_trigger)) {
> + /*
> + * It's not a problem if the trigger gpio isn't available, but
> + * it is worth a warning if its use was defined in the device
> + * tree.
> + */
> + if (PTR_ERR(data->gpio_trigger) != -ENOENT)
> + dev_err(&pdev->dev,
> + "unable to claim gpio \"trigger\"\n");
> + data->gpio_trigger = NULL;
> }
I just realized devm_gpiod_get_optional() may be slightly cleaner here,
but the difference isn't that big in the end:
+ data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger",
+ GPIOD_IN);
+ if (IS_ERR(data->gpio_trigger)) {
+ /*
+ * It's not a problem if the trigger gpio isn't available, but
+ * it is worth a warning if its use was defined in the device
+ * tree.
+ */
+ dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n");
+ data->gpio_trigger = NULL;
}
>
> - ret = devm_request_irq(&pdev->dev, virq,
> - ltc2952_poweroff_handler,
> - (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
> - "ltc2952-poweroff",
> - data);
> -
> - if (ret) {
> - dev_err(&pdev->dev, "cannot configure an interrupt handler\n");
> - return ret;
> + if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),
> + ltc2952_poweroff_handler,
> + (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
> + "ltc2952-poweroff",
> + data)) {
> + /*
> + * Some things may have happened:
> + * - No trigger input was defined
> + * - Claiming the GPIO failed
> + * - We could not map to an IRQ
> + * - We couldn't register an interrupt handler
> + *
> + * None of these really are problems, but all of them
> + * disqualify the push button from controlling the power.
> + *
> + * It is therefore important to note that if the ltc2952
> + * detects a button press for long enough, it will still start
> + * its own powerdown window and cut the power on us if we don't
> + * start the watchdog trigger.
> + */
> + if (data->gpio_trigger) {
> + dev_warn(&pdev->dev,
> + "unable to configure the trigger interrupt\n");
> + devm_gpiod_put(&pdev->dev, data->gpio_trigger);
> + data->gpio_trigger = NULL;
> + }
> + dev_info(&pdev->dev,
> + "power down trigger input will not be used\n");
> + ltc2952_poweroff_start_wde(data);
> }
>
> return 0;
> --
> 2.1.0
>
--
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