drivers/rtc/rtc-omap.c: add rtc wakeup support to alarm events

On some platforms (like AM33xx), a special register (RTC_IRQWAKEEN) is
available to enable Alarm Wakeup feature.  This register needs to be
properly handled for the rtcwake to work properly.

Platforms using such IP should set "ti,am3352-rtc" in rtc device dt
compatibility node.

Signed-off-by: Hebbar Gururaja <gururaja.hebbar@ti.com>
Acked-by: Kevin Hilman <khilman@linaro.org>
Acked-by: Sekhar Nori <nsekhar@ti.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Rob Landley <rob@landley.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/devicetree/bindings/rtc/rtc-omap.txt b/Documentation/devicetree/bindings/rtc/rtc-omap.txt
index b47aa41..5a0f02d 100644
--- a/Documentation/devicetree/bindings/rtc/rtc-omap.txt
+++ b/Documentation/devicetree/bindings/rtc/rtc-omap.txt
@@ -1,7 +1,11 @@
 TI Real Time Clock
 
 Required properties:
-- compatible: "ti,da830-rtc"
+- compatible:
+	- "ti,da830-rtc"  - for RTC IP used similar to that on DA8xx SoC family.
+	- "ti,am3352-rtc" - for RTC IP used similar to that on AM335x SoC family.
+			    This RTC IP has special WAKE-EN Register to enable
+			    Wakeup generation for event Alarm.
 - reg: Address range of rtc register set
 - interrupts: rtc timer, alarm interrupts in order
 - interrupt-parent: phandle for the interrupt controller