watchdog: menz069_wdt: fix watchdog initialisation

[ Upstream commit 87b2265 ]

Doing a 'cat /dev/watchdog0' with menz069_wdt as watchdog0 will result in
a NULL pointer dereference.

This happens because we're passing the wrong pointer to
watchdog_register_device(). Fix this by getting rid of the static
watchdog_device structure and use the one embedded into the driver's
per-instance private data.

Signed-off-by: Johannes Thumshirn <jth@kernel.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230418172531.177349-2-jth@kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/watchdog/menz69_wdt.c

@@ -98,14 +98,6 @@ static const struct watchdog_ops men_z069_ops = {
 	.set_timeout = men_z069_wdt_set_timeout,
 };
 
-static struct watchdog_device men_z069_wdt = {
-	.info = &men_z069_info,
-	.ops = &men_z069_ops,
-	.timeout = MEN_Z069_DEFAULT_TIMEOUT,
-	.min_timeout = 1,
-	.max_timeout = MEN_Z069_WDT_COUNTER_MAX / MEN_Z069_TIMER_FREQ,
-};
-
 static int men_z069_probe(struct mcb_device *dev,
 			  const struct mcb_device_id *id)
 {
@@ -125,15 +117,19 @@ static int men_z069_probe(struct mcb_device *dev,
 		goto release_mem;
 
 	drv->mem = mem;
+	drv->wdt.info = &men_z069_info;
+	drv->wdt.ops = &men_z069_ops;
+	drv->wdt.timeout = MEN_Z069_DEFAULT_TIMEOUT;
+	drv->wdt.min_timeout = 1;
+	drv->wdt.max_timeout = MEN_Z069_WDT_COUNTER_MAX / MEN_Z069_TIMER_FREQ;
 
-	drv->wdt = men_z069_wdt;
 	watchdog_init_timeout(&drv->wdt, 0, &dev->dev);
 	watchdog_set_nowayout(&drv->wdt, nowayout);
 	watchdog_set_drvdata(&drv->wdt, drv);
 	drv->wdt.parent = &dev->dev;
 	mcb_set_drvdata(dev, drv);
 
-	return watchdog_register_device(&men_z069_wdt);
+	return watchdog_register_device(&drv->wdt);
 
 release_mem:
 	mcb_release_mem(mem);