watchdog: sama5d4_wdt: Convert to use device managed functions and other improvements

Use device managed functions to simplify error handling, reduce
source code size, improve readability, and reduce the likelyhood of bugs.
Other improvements as listed below.

The conversion was done automatically with coccinelle using the
following semantic patches. The semantic patches and the scripts
used to generate this commit log are available at
https://github.com/groeck/coccinelle-patches

- Drop assignments to otherwise unused variables
- Drop empty remove function
- Introduce local variable 'struct device *dev' and use it instead of
  dereferencing it repeatedly
- Replace stop on remove with call to watchdog_stop_on_unregister()
- Use devm_watchdog_register_driver() to register watchdog device

Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/sama5d4_wdt.c

@@ -199,6 +199,7 @@ static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
 
 static int sama5d4_wdt_probe(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
 	struct watchdog_device *wdd;
 	struct sama5d4_wdt *wdt;
 	void __iomem *regs;
@@ -206,7 +207,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 	u32 timeout;
 	int ret;
 
-	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 	if (!wdt)
 		return -ENOMEM;
 
@@ -226,26 +227,25 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 
 	wdt->reg_base = regs;
 
-	irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
+	irq = irq_of_parse_and_map(dev->of_node, 0);
 	if (!irq)
-		dev_warn(&pdev->dev, "failed to get IRQ from DT\n");
+		dev_warn(dev, "failed to get IRQ from DT\n");
 
-	ret = of_sama5d4_wdt_init(pdev->dev.of_node, wdt);
+	ret = of_sama5d4_wdt_init(dev->of_node, wdt);
 	if (ret)
 		return ret;
 
 	if ((wdt->mr & AT91_WDT_WDFIEN) && irq) {
-		ret = devm_request_irq(&pdev->dev, irq, sama5d4_wdt_irq_handler,
+		ret = devm_request_irq(dev, irq, sama5d4_wdt_irq_handler,
 				       IRQF_SHARED | IRQF_IRQPOLL |
 				       IRQF_NO_SUSPEND, pdev->name, pdev);
 		if (ret) {
-			dev_err(&pdev->dev,
-				"cannot register interrupt handler\n");
+			dev_err(dev, "cannot register interrupt handler\n");
 			return ret;
 		}
 	}
 
-	watchdog_init_timeout(wdd, wdt_timeout, &pdev->dev);
+	watchdog_init_timeout(wdd, wdt_timeout, dev);
 
 	timeout = WDT_SEC2TICKS(wdd->timeout);
 
@@ -258,31 +258,21 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 
 	watchdog_set_nowayout(wdd, nowayout);
 
-	ret = watchdog_register_device(wdd);
+	watchdog_stop_on_unregister(wdd);
+	ret = devm_watchdog_register_device(dev, wdd);
 	if (ret) {
-		dev_err(&pdev->dev, "failed to register watchdog device\n");
+		dev_err(dev, "failed to register watchdog device\n");
 		return ret;
 	}
 
 	platform_set_drvdata(pdev, wdt);
 
-	dev_info(&pdev->dev, "initialized (timeout = %d sec, nowayout = %d)\n",
+	dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
 		 wdd->timeout, nowayout);
 
 	return 0;
 }
 
-static int sama5d4_wdt_remove(struct platform_device *pdev)
-{
-	struct sama5d4_wdt *wdt = platform_get_drvdata(pdev);
-
-	sama5d4_wdt_stop(&wdt->wdd);
-
-	watchdog_unregister_device(&wdt->wdd);
-
-	return 0;
-}
-
 static const struct of_device_id sama5d4_wdt_of_match[] = {
 	{ .compatible = "atmel,sama5d4-wdt", },
 	{ }
@@ -310,7 +300,6 @@ static SIMPLE_DEV_PM_OPS(sama5d4_wdt_pm_ops, NULL,
 
 static struct platform_driver sama5d4_wdt_driver = {
 	.probe		= sama5d4_wdt_probe,
-	.remove		= sama5d4_wdt_remove,
 	.driver		= {
 		.name	= "sama5d4_wdt",
 		.pm	= &sama5d4_wdt_pm_ops,