watchdog: WatchDog Timer Driver Core - Add basic framework

The WatchDog Timer Driver Core is a framework
that contains the common code for all watchdog-driver's.
It also introduces a watchdog device structure and the
operations that go with it.

This is the introduction of this framework. This part
supports the minimal watchdog userspace API (or with
other words: the functionality to use /dev/watchdog's
open, release and write functionality as defined in
the simplest watchdog API). Extra functionality will
follow in the next set of patches.

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>

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 0635e72..f441726 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -28,6 +28,17 @@
 
 if WATCHDOG
 
+config WATCHDOG_CORE
+	bool "WatchDog Timer Driver Core"
+	---help---
+	  Say Y here if you want to use the new watchdog timer driver core.
+	  This driver provides a framework for all watchdog timer drivers
+	  and gives them the /dev/watchdog interface (and later also the
+	  sysfs interface).
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called watchdog.
+
 config WATCHDOG_NOWAYOUT
 	bool "Disable watchdog shutdown on close"
 	help