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>
---
v4: Fix 'return' with a value, in function returning void
.../devicetree/bindings/watchdog/gpio-wdt.txt | 5 +++
drivers/watchdog/gpio_wdt.c | 37 +++++++++++++++-----
2 files changed, 34 insertions(+), 8 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..51acda6 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;
@@ -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;
}
--
1.7.9.5
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