watchdog: add driver for Ricoh RN5T618 watchdog

This adds a driver for the watchdog timer available in Ricoh RN5T618
PMIC. The device supports a programmable expiration time of 1, 8, 32
or 128 seconds.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-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 17b39b8..4edae088 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -327,6 +327,17 @@
 	  To compile this driver as a module, choose M here: the
 	  module will be called orion_wdt.
 
+config RN5T618_WATCHDOG
+	tristate "Ricoh RN5T618 watchdog"
+	depends on MFD_RN5T618
+	select WATCHDOG_CORE
+	help
+	  If you say yes here you get support for watchdog on the Ricoh
+	  RN5T618 PMIC.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called rn5t618_wdt.
+
 config SUNXI_WATCHDOG
 	tristate "Allwinner SoCs watchdog support"
 	depends on ARCH_SUNXI