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 <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

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

···
 - 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

···
 #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>
···
 
 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;
 
 	wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
 	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);