watchdog: imx2_wdt: adds big endianness support.

This watchdog driver will be working on IMX2+, Vybrid, LS1, LS2+
platforms, and will be in different endianness mode in those SoCs:

    SoCs       WDT endian mode
------------------------------------
    IMX2+           LE
    Vybird          LE
    LS1             BE
    LS2             LE

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

Documentation/devicetree/bindings/watchdog/fsl-imx-wdt.txt

@@ -5,10 +5,15 @@ Required properties:
 - reg : Should contain WDT registers location and length
 - interrupts : Should contain WDT interrupt
 
+Optional property:
+- big-endian: If present the watchdog device's registers are implemented
+  in big endian mode, otherwise in little mode.
+
 Examples:
 
 wdt@73f98000 {
 	compatible = "fsl,imx51-wdt", "fsl,imx21-wdt";
 	reg = <0x73f98000 0x4000>;
 	interrupts = <58>;
+	big-endian;
 };

drivers/watchdog/imx2_wdt.c

@@ -28,6 +28,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/timer.h>
@@ -190,10 +191,12 @@ static struct regmap_config imx2_wdt_regmap_config = {
 
 static int __init imx2_wdt_probe(struct platform_device *pdev)
 {
+	struct device_node *np = pdev->dev.of_node;
 	struct imx2_wdt_device *wdev;
 	struct watchdog_device *wdog;
 	struct resource *res;
 	void __iomem *base;
+	bool big_endian;
 	int ret;
 	u32 val;
 
@@ -201,6 +204,10 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
 	if (!wdev)
 		return -ENOMEM;
 
+	big_endian = of_property_read_bool(np, "big-endian");
+	if (big_endian)
+		imx2_wdt_regmap_config.val_format_endian = REGMAP_ENDIAN_BIG;
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(base))