drivers/rtc/rtc-ds1374.c: add watchdog support

Add support for the watchdog functionality of the DS1374 rtc.  Based on
the m41t80 watchdog functionality Note: watchdog uses the same registers
as alarm.

[akpm@linux-foundation.org: don't forget mutex_unlock() in ds1374_wdt_open() error path]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Soeren Andersen <san@rosetechnology.dk>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index b682651..4511ddc 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -192,6 +192,14 @@
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-ds1374.
 
+config RTC_DRV_DS1374_WDT
+	bool "Dallas/Maxim DS1374 watchdog timer"
+	depends on RTC_DRV_DS1374
+	help
+	  If you say Y here you will get support for the
+	  watchdog timer in the Dallas Semiconductor DS1374
+	  real-time clock chips.
+
 config RTC_DRV_DS1672
 	tristate "Dallas/Maxim DS1672"
 	help