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Commit ba804a95 authored by Mike Looijmans's avatar Mike Looijmans Committed by Wim Van Sebroeck
Browse files

watchdog: gpio_wdt: Add "always_running" feature to GPIO watchdog 



On some chips, like the TPS386000, the trigger cannot be disabled
and the CPU must keep toggling the line at all times. Add a switch
"always_running" to keep toggling the GPIO line regardless of the
state of the soft part of the watchdog. The "armed" member keeps
track of whether a timeout must also cause a reset.

Signed-off-by: default avatarMike Looijmans <mike.looijmans@topic.nl>
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarWim Van Sebroeck <wim@iguana.be>
parent 396f163c

Documentation/devicetree/bindings/watchdog/gpio-wdt.txt

+5 −0
Original line number Diff line number Diff line
@@ -13,6 +13,11 @@ Required Properties: 
    by the GPIO flags.

- hw_margin_ms: Maximum time to reset watchdog circuit (milliseconds).



Optional Properties:

- always-running: If the watchdog timer cannot be disabled, add this flag to

  have the driver keep toggling the signal without a client. It will only cease

  to toggle the signal when the device is open and the timeout elapsed.



Example:

	watchdog: watchdog {

		/* ADM706 */

drivers/watchdog/gpio_wdt.c

+29 −8
Original line number Diff line number Diff line
@@ -31,6 +31,8 @@ struct gpio_wdt_priv { 
	int			gpio;

	bool			active_low;

	bool			state;

	bool			always_running;

	bool			armed;

	unsigned int		hw_algo;

	unsigned int		hw_margin;

	unsigned long		last_jiffies;
@@ -48,14 +50,20 @@ static void gpio_wdt_disable(struct gpio_wdt_priv *priv) 
		gpio_direction_input(priv->gpio);

}



static int gpio_wdt_start(struct watchdog_device *wdd)

static void gpio_wdt_start_impl(struct gpio_wdt_priv *priv)

{

	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);



	priv->state = priv->active_low;

	gpio_direction_output(priv->gpio, priv->state);

	priv->last_jiffies = jiffies;

	mod_timer(&priv->timer, priv->last_jiffies + priv->hw_margin);

}



static int gpio_wdt_start(struct watchdog_device *wdd)

{

	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);



	gpio_wdt_start_impl(priv);

	priv->armed = true;



	return 0;

}
@@ -64,8 +72,11 @@ static int gpio_wdt_stop(struct watchdog_device *wdd) 
{

	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);



	priv->armed = false;

	if (!priv->always_running) {

		mod_timer(&priv->timer, 0);

		gpio_wdt_disable(priv);

	}



	return 0;

}
@@ -91,7 +102,7 @@ static void gpio_wdt_hwping(unsigned long data) 
	struct watchdog_device *wdd = (struct watchdog_device *)data;

	struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);



	if (time_after(jiffies, priv->last_jiffies +

	if (priv->armed && time_after(jiffies, priv->last_jiffies +

				      msecs_to_jiffies(wdd->timeout * 1000))) {

		dev_crit(wdd->dev, "Timer expired. System will reboot soon!\n");

		return;
@@ -197,6 +208,9 @@ static int gpio_wdt_probe(struct platform_device *pdev) 
	/* Use safe value (1/2 of real timeout) */

	priv->hw_margin = msecs_to_jiffies(hw_margin / 2);



	priv->always_running = of_property_read_bool(pdev->dev.of_node,

						     "always-running");



	watchdog_set_drvdata(&priv->wdd, priv);



	priv->wdd.info		= &gpio_wdt_ident;
@@ -216,8 +230,15 @@ static int gpio_wdt_probe(struct platform_device *pdev) 
	priv->notifier.notifier_call = gpio_wdt_notify_sys;

	ret = register_reboot_notifier(&priv->notifier);

	if (ret)

		watchdog_unregister_device(&priv->wdd);

		goto error_unregister;



	if (priv->always_running)

		gpio_wdt_start_impl(priv);



	return 0;



error_unregister:

	watchdog_unregister_device(&priv->wdd);

	return ret;

}