On 11/20/2014 10:53 PM, Mike Looijmans wrote:
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@xxxxxxxx>
---
v2: Rename property "always_running" to "always-running" and add devicetree
documentation
.../devicetree/bindings/watchdog/gpio-wdt.txt | 5 +++++
drivers/watchdog/gpio_wdt.c | 20 +++++++++++++++++---
2 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
index 37afec1..1987949 100644
--- a/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
+++ b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
@@ -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 */
diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
index 220a9e0..3266215 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;
Please align columns with the other variables.
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))) {
Please align continuation lines.
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");
+
Please align continuation line with '('.
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;
+ }
+
This won't work if there is an error. The driver won't load but the timer
is started, which will likely cause a crash when the timer fires. You'll
have to fix the error handling.
I also dislike that you first set priv->armed in the start function and
then reset it, but I don't have a better idea right now.
Guenter
return ret;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
