watchdog: at91sam9_wdt: update device tree doc

Add new at91sam9 watchdog properties to the documentation.
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

Documentation/devicetree/bindings/watchdog/atmel-wdt.txt

@@ -9,11 +9,37 @@ Required properties:
 
 Optional properties:
 - timeout-sec: contains the watchdog timeout in seconds.
+- interrupts : Should contain WDT interrupt.
+- atmel,max-heartbeat-sec : Should contain the maximum heartbeat value in
+	seconds. This value should be less or equal to 16. It is used to
+	compute the WDV field.
+- atmel,min-heartbeat-sec : Should contain the minimum heartbeat value in
+	seconds. This value must be smaller than the max-heartbeat-sec value.
+	It is used to compute the WDD field.
+- atmel,watchdog-type : Should be "hardware" or "software". Hardware watchdog
+	use the at91 watchdog reset. Software watchdog use the watchdog
+	interrupt to trigger a software reset.
+- atmel,reset-type : Should be "proc" or "all".
+	"all" : assert peripherals and processor reset signals
+	"proc" : assert the processor reset signal
+	This is valid only when using "hardware" watchdog.
+- atmel,disable : Should be present if you want to disable the watchdog.
+- atmel,idle-halt : Should be present if you want to stop the watchdog when
+	entering idle state.
+- atmel,dbg-halt : Should be present if you want to stop the watchdog when
+	entering debug state.
 
 Example:
-
 	watchdog@fffffd40 {
 		compatible = "atmel,at91sam9260-wdt";
 		reg = <0xfffffd40 0x10>;
-		timeout-sec = <10>;
+		interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>;
+		timeout-sec = <15>;
+		atmel,watchdog-type = "hardware";
+		atmel,reset-type = "all";
+		atmel,dbg-halt;
+		atmel,idle-halt;
+		atmel,max-heartbeat-sec = <16>;
+		atmel,min-heartbeat-sec = <0>;
+		status = "okay";
 	};