dm: Simple Watchdog uclass

This is a simple uclass for Watchdog Timers. It has four operations:
start, restart, reset, stop. Drivers must implement start, restart and
stop operations, while implementing reset is optional: It's default
implementation expires watchdog timer in one clock tick.

Signed-off-by: Maxim Sloyko <maxims@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index dbdaafc..e8d2dba 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1,8 +1,26 @@
-menu "WATCHDOG support"
+menu "Watchdog Timer Support"
 
 config ULP_WATCHDOG
 	bool "i.MX7ULP watchdog"
 	help
 	  Say Y here to enable i.MX7ULP watchdog driver.
 
+config WDT
+	bool "Enable driver model for watchdog timer drivers"
+	depends on DM
+	help
+	  Enable driver model for watchdog timer. At the moment the API
+	  is very simple and only supports four operations:
+	  start, restart, stop and reset (expire immediately).
+	  What exactly happens when the timer expires is up to a particular
+	  device/driver.
+
+config WDT_SANDBOX
+	bool "Enable Watchdog Timer support for Sandbox"
+	depends on SANDBOX && WDT
+	help
+		Enable Watchdog Timer support in Sandbox. This is a dummy device that
+		can be probed and supports all of the methods of WDT, but does not
+		really do anything.
+
 endmenu