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

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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: Mike Looijmans <mike.looijmans@topic.nl>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Mike Looijmans 2015-01-14 07:28:29 +01:00 committed by Wim Van Sebroeck
parent 396f163ceb
commit ba804a9510
2 changed files with 34 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
View File

@ -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 */

37
drivers/watchdog/gpio_wdt.c
View File

@ -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);
mod_timer(&priv->timer, 0);
gpio_wdt_disable(priv);
priv->armed = false;
if (!priv->always_running) {
mod_timer(&priv->timer, 0);
gpio_wdt_disable(priv);
}
return 0;
}
@ -91,8 +102,8 @@ 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 +
msecs_to_jiffies(wdd->timeout * 1000))) {
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;
}