watchdog: omap_wdt: implement get_timeleft

The omap watchdog hardware is able to read the watchdog timer counter
register. This implements this functionality in the omap_wdt driver, so
one is can read the time until the watchdog will trigger the reset in
seconds using WDIOC_GETTIMELEFT.

Signed-off-by: Lars Poeschel <poeschel@lemonage.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
diff --git a/drivers/watchdog/omap_wdt.h b/drivers/watchdog/omap_wdt.h
index 09b774c..42f31ec 100644
--- a/drivers/watchdog/omap_wdt.h
+++ b/drivers/watchdog/omap_wdt.h
@@ -50,5 +50,6 @@
 
 #define PTV			0	/* prescale */
 #define GET_WLDR_VAL(secs)	(0xffffffff - ((secs) * (32768/(1<<PTV))) + 1)
+#define GET_WCCR_SECS(val)	((0xffffffff - (val) + 1) / (32768/(1<<PTV)))
 
 #endif				/* _OMAP_WATCHDOG_H */