[PATCH] gpio_wdt: Add "always_running" feature to GPIO watchdog

Mike Looijmans
2014-11-20T13:16:34Z

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>
---
drivers/watchdog/gpio_wdt.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
index 220a9e0..921ee67 100644
--- a/drivers/watchdog/gpio_wdt.c
+++ b/drivers/watchdog/gpio_wdt.c
@@ -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;
@@ -56,6 +58,7 @@ static int gpio_wdt_start(struct watchdog_device *wdd)
gpio_direction_output(priv->gpio, priv->state);
priv->last_jiffies = jiffies;
mod_timer(&priv->timer, priv->last_jiffies + priv->hw_margin);
+ priv->armed = true;

return 0;
}
@@ -64,8 +67,11 @@ 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;
}
@@ -91,7 +97,7 @@ 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 +203,9 @@ 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;
@@ -218,6 +227,11 @@ static int gpio_wdt_probe(struct platform_device *pdev)
if (ret)
watchdog_unregister_device(&priv->wdd);

+ if (priv->always_running) {
+ gpio_wdt_start(&priv->wdd);
+ priv->armed = false;
+ }
+
return ret;
}

--
1.7.9.5