watchdog: Xen watchdog driver

While the hypervisor change adding SCHEDOP_watchdog support included a
daemon to make use of the new functionality, having a kernel driver
for /dev/watchdog so that user space code doesn't need to distinguish
non-Xen and Xen seems to be preferable.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 28a9835..6c216f9 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1137,6 +1137,16 @@
 
 # XTENSA Architecture
 
+# Xen Architecture
+
+config XEN_WDT
+	tristate "Xen Watchdog support"
+	depends on XEN
+	help
+	  Say Y here to support the hypervisor watchdog capability provided
+	  by Xen 4.0 and newer.  The watchdog timeout period is normally one
+	  minute but can be changed with a boot-time parameter.
+
 #
 # ISA-based Watchdog Cards
 #