watchdog: stmp3xxx: Stop the watchdog on system halt

This allows the system to actually halt even if userspace forgot to
disable the watchdog first. Old behaviour was that the watchdog forced
the system to boot again.
Signed-off-by: NHarald Geyer <harald@ccbib.org>
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NWim Van Sebroeck <wim@iguana.be>

drivers/watchdog/stmp3xxx_rtc_wdt.c

@@ -14,6 +14,8 @@
 #include <linux/watchdog.h>
 #include <linux/platform_device.h>
 #include <linux/stmp3xxx_rtc_wdt.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
 
 #define WDOG_TICK_RATE 1000 /* 1 kHz clock */
 #define STMP3XXX_DEFAULT_TIMEOUT 19
@@ -69,6 +71,28 @@ static struct watchdog_device stmp3xxx_wdd = {
 	.status = WATCHDOG_NOWAYOUT_INIT_STATUS,
 };
 
+static int wdt_notify_sys(struct notifier_block *nb, unsigned long code,
+			  void *unused)
+{
+	struct device *dev = watchdog_get_drvdata(&stmp3xxx_wdd);
+	struct stmp3xxx_wdt_pdata *pdata = dev_get_platdata(dev);
+
+	switch (code) {
+	case SYS_DOWN:	/* keep enabled, system might crash while going down */
+		break;
+	case SYS_HALT:	/* allow the system to actually halt */
+	case SYS_POWER_OFF:
+		wdt_stop(&stmp3xxx_wdd);
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block wdt_notifier = {
+	.notifier_call = wdt_notify_sys,
+};
+
 static int stmp3xxx_wdt_probe(struct platform_device *pdev)
 {
 	int ret;
@@ -84,6 +108,9 @@ static int stmp3xxx_wdt_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	if (register_reboot_notifier(&wdt_notifier))
+		dev_warn(&pdev->dev, "cannot register reboot notifier\n");
+
 	dev_info(&pdev->dev, "initialized watchdog with heartbeat %ds\n",
 			stmp3xxx_wdd.timeout);
 	return 0;
@@ -91,6 +118,7 @@ static int stmp3xxx_wdt_probe(struct platform_device *pdev)
 
 static int stmp3xxx_wdt_remove(struct platform_device *pdev)
 {
+	unregister_reboot_notifier(&wdt_notifier);
 	watchdog_unregister_device(&stmp3xxx_wdd);
 	return 0;
 }