watchdog: lpc18xx_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

- Use devm_add_action_or_reset() for calls to clk_disable_unprepare
- Use local variable 'struct device *dev' consistently
- Use devm_watchdog_register_driver() to register watchdog device
- Replace shutdown function with call to watchdog_stop_on_reboot()

Cc: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/lpc18xx_wdt.c

@@ -200,6 +200,11 @@ static const struct watchdog_ops lpc18xx_wdt_ops = {
 	.restart        = lpc18xx_wdt_restart,
 };
 
+static void lpc18xx_clk_disable_unprepare(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
 static int lpc18xx_wdt_probe(struct platform_device *pdev)
 {
 	struct lpc18xx_wdt_dev *lpc18xx_wdt;
@@ -231,19 +236,26 @@ static int lpc18xx_wdt_probe(struct platform_device *pdev)
 		dev_err(dev, "could not prepare or enable sys clock\n");
 		return ret;
 	}
+	ret = devm_add_action_or_reset(dev, lpc18xx_clk_disable_unprepare,
+				       lpc18xx_wdt->reg_clk);
+	if (ret)
+		return ret;
 
 	ret = clk_prepare_enable(lpc18xx_wdt->wdt_clk);
 	if (ret) {
 		dev_err(dev, "could not prepare or enable wdt clock\n");
-		goto disable_reg_clk;
+		return ret;
 	}
+	ret = devm_add_action_or_reset(dev, lpc18xx_clk_disable_unprepare,
+				       lpc18xx_wdt->wdt_clk);
+	if (ret)
+		return ret;
 
 	/* We use the clock rate to calculate timeouts */
 	lpc18xx_wdt->clk_rate = clk_get_rate(lpc18xx_wdt->wdt_clk);
 	if (lpc18xx_wdt->clk_rate == 0) {
 		dev_err(dev, "failed to get clock rate\n");
-		ret = -EINVAL;
-		goto disable_wdt_clk;
+		return -EINVAL;
 	}
 
 	lpc18xx_wdt->wdt_dev.info = &lpc18xx_wdt_info;
@@ -274,24 +286,8 @@ static int lpc18xx_wdt_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, lpc18xx_wdt);
 
-	ret = watchdog_register_device(&lpc18xx_wdt->wdt_dev);
-	if (ret)
-		goto disable_wdt_clk;
-
-	return 0;
-
-disable_wdt_clk:
-	clk_disable_unprepare(lpc18xx_wdt->wdt_clk);
-disable_reg_clk:
-	clk_disable_unprepare(lpc18xx_wdt->reg_clk);
-	return ret;
-}
-
-static void lpc18xx_wdt_shutdown(struct platform_device *pdev)
-{
-	struct lpc18xx_wdt_dev *lpc18xx_wdt = platform_get_drvdata(pdev);
-
-	lpc18xx_wdt_stop(&lpc18xx_wdt->wdt_dev);
+	watchdog_stop_on_reboot(&lpc18xx_wdt->wdt_dev);
+	return devm_watchdog_register_device(dev, &lpc18xx_wdt->wdt_dev);
 }
 
 static int lpc18xx_wdt_remove(struct platform_device *pdev)
@@ -301,10 +297,6 @@ static int lpc18xx_wdt_remove(struct platform_device *pdev)
 	dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n");
 	del_timer(&lpc18xx_wdt->timer);
 
-	watchdog_unregister_device(&lpc18xx_wdt->wdt_dev);
-	clk_disable_unprepare(lpc18xx_wdt->wdt_clk);
-	clk_disable_unprepare(lpc18xx_wdt->reg_clk);
-
 	return 0;
 }
 
@@ -321,7 +313,6 @@ static struct platform_driver lpc18xx_wdt_driver = {
 	},
 	.probe = lpc18xx_wdt_probe,
 	.remove = lpc18xx_wdt_remove,
-	.shutdown = lpc18xx_wdt_shutdown,
 };
 module_platform_driver(lpc18xx_wdt_driver);