watchdog: at91sam9_wdt: add device tree support

Tested on an at91sam9260 board (evk-pro3)
Signed-off-by: Fabio Porcedda <fabio.porcedda@gmail.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

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

+* Atmel Watchdog Timers
+
+** at91sam9-wdt
+
+Required properties:
+- compatible: must be "atmel,at91sam9260-wdt".
+- reg: physical base address of the controller and length of memory mapped
+  region.
+
+Example:
+
+	watchdog@fffffd40 {
+		compatible = "atmel,at91sam9260-wdt";
+		reg = <0xfffffd40 0x10>;
+	};

drivers/watchdog/at91sam9_wdt.c

@@ -32,6 +32,7 @@
 #include <linux/timer.h>
 #include <linux/bitops.h>
 #include <linux/uaccess.h>
+#include <linux/of.h>
 
 #include "at91sam9_wdt.h"
 
@@ -302,11 +303,21 @@ static int __exit at91wdt_remove(struct platform_device *pdev)
 	return res;
 }
 
+#if defined(CONFIG_OF)
+static const struct of_device_id at91_wdt_dt_ids[] __initconst = {
+	{ .compatible = "atmel,at91sam9260-wdt" },
+	{ /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, at91_wdt_dt_ids);
+#endif
+
 static struct platform_driver at91wdt_driver = {
 	.remove		= __exit_p(at91wdt_remove),
 	.driver		= {
 		.name	= "at91_wdt",
 		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(at91_wdt_dt_ids),
 	},
 };