ARM: at91: add Shutdown Controller (SHDWC) DT support

Use a string to specific the wakeup mode to make it more readable.

Add the Real-time Clock Wake-up support too for sam9g45 and sam9x5.
Add AT91_SHDW_CPTWK0_MAX to specific the Max of the Wakeup Counter.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/Documentation/devicetree/bindings/arm/atmel-at91.txt b/Documentation/devicetree/bindings/arm/atmel-at91.txt
index 1f87820..ecc81e3 100644
--- a/Documentation/devicetree/bindings/arm/atmel-at91.txt
+++ b/Documentation/devicetree/bindings/arm/atmel-at91.txt
@@ -61,3 +61,32 @@
 		reg = <0xffffe400 0x200
 		       0xffffe600 0x200>;
 	};
+
+SHDWC Shutdown Controller
+
+required properties:
+- compatible: Should be "atmel,<chip>-shdwc".
+  <chip> can be "at91sam9260", "at91sam9rl" or "at91sam9x5".
+- reg: Should contain registers location and length
+
+optional properties:
+- atmel,wakeup-mode: String, operation mode of the wakeup mode.
+  Supported values are: "none", "high", "low", "any".
+- atmel,wakeup-counter: Counter on Wake-up 0 (between 0x0 and 0xf).
+
+optional at91sam9260 properties:
+- atmel,wakeup-rtt-timer: boolean to enable Real-time Timer Wake-up.
+
+optional at91sam9rl properties:
+- atmel,wakeup-rtc-timer: boolean to enable Real-time Clock Wake-up.
+- atmel,wakeup-rtt-timer: boolean to enable Real-time Timer Wake-up.
+
+optional at91sam9x5 properties:
+- atmel,wakeup-rtc-timer: boolean to enable Real-time Clock Wake-up.
+
+Example:
+
+	rstc@fffffd00 {
+		compatible = "atmel,at91sam9260-rstc";
+		reg = <0xfffffd00 0x10>;
+	};