watchdog: imgpdc: Add reboot support

Register a restart handler that will restart the system by writing
to the watchdog's SOFT_RESET register.

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Reviewed-by: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Tested-by: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/imgpdc_wdt.c

@@ -16,6 +16,7 @@
 #include <linux/log2.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/reboot.h>
 #include <linux/slab.h>
 #include <linux/watchdog.h>
 
@@ -57,6 +58,7 @@ struct pdc_wdt_dev {
 	struct clk *wdt_clk;
 	struct clk *sys_clk;
 	void __iomem *base;
+	struct notifier_block restart_handler;
 };
 
 static int pdc_wdt_keepalive(struct watchdog_device *wdt_dev)
@@ -136,6 +138,18 @@ static const struct watchdog_ops pdc_wdt_ops = {
 	.set_timeout	= pdc_wdt_set_timeout,
 };
 
+static int pdc_wdt_restart(struct notifier_block *this, unsigned long mode,
+			   void *cmd)
+{
+	struct pdc_wdt_dev *wdt = container_of(this, struct pdc_wdt_dev,
+					       restart_handler);
+
+	/* Assert SOFT_RESET */
+	writel(0x1, wdt->base + PDC_WDT_SOFT_RESET);
+
+	return NOTIFY_OK;
+}
+
 static int pdc_wdt_probe(struct platform_device *pdev)
 {
 	int ret, val;
@@ -242,6 +256,13 @@ static int pdc_wdt_probe(struct platform_device *pdev)
 	if (ret)
 		goto disable_wdt_clk;
 
+	pdc_wdt->restart_handler.notifier_call = pdc_wdt_restart;
+	pdc_wdt->restart_handler.priority = 128;
+	ret = register_restart_handler(&pdc_wdt->restart_handler);
+	if (ret)
+		dev_warn(&pdev->dev, "failed to register restart handler: %d\n",
+			 ret);
+
 	return 0;
 
 disable_wdt_clk: