watchdog: WatchDog Timer Driver Core - Add WDIOC_KEEPALIVE ioctl

This part add's the WDIOC_KEEPALIVE ioctl functionality to the
WatchDog Timer Driver Core framework. Please note that the
WDIOF_KEEPALIVEPING bit has to be set in the watchdog_info
options field.

Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>

drivers/watchdog/watchdog_dev.c

@@ -120,6 +120,11 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
 		return put_user(val, p);
 	case WDIOC_GETBOOTSTATUS:
 		return put_user(wdd->bootstatus, p);
+	case WDIOC_KEEPALIVE:
+		if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
+			return -EOPNOTSUPP;
+		watchdog_ping(wdd);
+		return 0;
 	default:
 		return -ENOTTY;
 	}