[PATCH 2/2] watchdog: gpio-wdt: Add panic notifier

[Alexander Stein <alexander.stein@systec-electronic.com>]

This notifier is required when the watchdog is configured as always running
because in this case the watchdog will be triggered when the kernel panics
at boot before any application could open the device, e.g. because the
rootfs is broken. This should result in a resetting system. Thus we
register a panic notifier which stops triggering the watchdog.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
---
 drivers/watchdog/gpio_wdt.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
index c7b8a06..aaa0815 100644
--- a/drivers/watchdog/gpio_wdt.c
+++ b/drivers/watchdog/gpio_wdt.c
@@ -37,6 +37,7 @@ struct gpio_wdt_priv {
 	unsigned int		hw_margin;
 	unsigned long		last_jiffies;
 	struct notifier_block	reboot_notifier;
+	struct notifier_block	panic_notifier;
 	struct timer_list	timer;
 	struct watchdog_device	wdd;
 };
@@ -146,6 +147,17 @@ static int gpio_wdt_notify_sys(struct notifier_block *nb, unsigned long code,
 	return NOTIFY_DONE;
 }
 
+static int gpio_wdt_notify_panic(struct notifier_block *nb, unsigned long code,
+			       void *unused)
+{
+	struct gpio_wdt_priv *priv = container_of(nb, struct gpio_wdt_priv,
+						  panic_notifier);
+
+	gpio_wdt_disable(priv);
+
+	return NOTIFY_DONE;
+}
+
 static const struct watchdog_info gpio_wdt_ident = {
 	.options	= WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING |
 			  WDIOF_SETTIMEOUT,
@@ -233,11 +245,19 @@ static int gpio_wdt_probe(struct platform_device *pdev)
 	if (ret)
 		goto error_unregister;
 
+	priv->panic_notifier.notifier_call = gpio_wdt_notify_panic;
+	ret = atomic_notifier_chain_register(&panic_notifier_list,
+					     &priv->panic_notifier);
+	if (ret)
+		goto error_unregister_notify;
+
 	if (priv->always_running)
 		gpio_wdt_start_impl(priv);
 
 	return 0;
 
+error_unregister_notify:
+	unregister_reboot_notifier(&priv->reboot_notifier);
 error_unregister:
 	watchdog_unregister_device(&priv->wdd);
 	return ret;
-- 
2.4.10