watchdog: core: add option to avoid early handling of watchdog

On some systems its desirable to have watchdog reboot the system
when it does not come up fast enough. This adds a kernel parameter
to disable the auto-update of watchdog before userspace takes over
and a kernel option to set the default. The info messages were
added to shorten error searching on misconfigured systems.

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 2696493..e9da196 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -46,6 +46,17 @@
 	  get killed. If you say Y here, the watchdog cannot be stopped once
 	  it has been started.
 
+config WATCHDOG_HANDLE_BOOT_ENABLED
+	bool "Update boot-enabled watchdog until userspace takes over"
+	default y
+	help
+	  The default watchdog behaviour (which you get if you say Y here) is
+	  to ping watchdog devices that were enabled before the driver has
+	  been loaded until control is taken over from userspace using the
+	  /dev/watchdog file. If you say N here, the kernel will not update
+	  the watchdog on its own. Thus if your userspace does not start fast
+	  enough your device will reboot.
+
 config WATCHDOG_SYSFS
 	bool "Read different watchdog information through sysfs"
 	help