watchdog: loongson1_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 unnecessary braces around conditional return statements
- Drop empty remove function
- Use devm_add_action_or_reset() for calls to clk_disable_unprepare
- Introduce local variable 'struct device *dev' and use it instead of
  dereferencing it repeatedly
- Use devm_watchdog_register_driver() to register watchdog device

Cc: Keguang Zhang <keguang.zhang@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/loongson1_wdt.c

@@ -83,14 +83,20 @@ static const struct watchdog_ops ls1x_wdt_ops = {
 	.set_timeout = ls1x_wdt_set_timeout,
 };
 
+static void ls1x_clk_disable_unprepare(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
 static int ls1x_wdt_probe(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
 	struct ls1x_wdt_drvdata *drvdata;
 	struct watchdog_device *ls1x_wdt;
 	unsigned long clk_rate;
 	int err;
 
-	drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
+	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
 	if (!drvdata)
 		return -ENOMEM;
 
@@ -98,21 +104,23 @@ static int ls1x_wdt_probe(struct platform_device *pdev)
 	if (IS_ERR(drvdata->base))
 		return PTR_ERR(drvdata->base);
 
-	drvdata->clk = devm_clk_get(&pdev->dev, pdev->name);
+	drvdata->clk = devm_clk_get(dev, pdev->name);
 	if (IS_ERR(drvdata->clk))
 		return PTR_ERR(drvdata->clk);
 
 	err = clk_prepare_enable(drvdata->clk);
 	if (err) {
-		dev_err(&pdev->dev, "clk enable failed\n");
+		dev_err(dev, "clk enable failed\n");
 		return err;
 	}
+	err = devm_add_action_or_reset(dev, ls1x_clk_disable_unprepare,
+				       drvdata->clk);
+	if (err)
+		return err;
 
 	clk_rate = clk_get_rate(drvdata->clk);
-	if (!clk_rate) {
-		err = -EINVAL;
-		goto err0;
-	}
+	if (!clk_rate)
+		return -EINVAL;
 	drvdata->clk_rate = clk_rate;
 
 	ls1x_wdt = &drvdata->wdt;
@@ -121,41 +129,27 @@ static int ls1x_wdt_probe(struct platform_device *pdev)
 	ls1x_wdt->timeout = DEFAULT_HEARTBEAT;
 	ls1x_wdt->min_timeout = 1;
 	ls1x_wdt->max_hw_heartbeat_ms = U32_MAX / clk_rate * 1000;
-	ls1x_wdt->parent = &pdev->dev;
+	ls1x_wdt->parent = dev;
 
-	watchdog_init_timeout(ls1x_wdt, heartbeat, &pdev->dev);
+	watchdog_init_timeout(ls1x_wdt, heartbeat, dev);
 	watchdog_set_nowayout(ls1x_wdt, nowayout);
 	watchdog_set_drvdata(ls1x_wdt, drvdata);
 
-	err = watchdog_register_device(&drvdata->wdt);
+	err = devm_watchdog_register_device(dev, &drvdata->wdt);
 	if (err) {
-		dev_err(&pdev->dev, "failed to register watchdog device\n");
-		goto err0;
+		dev_err(dev, "failed to register watchdog device\n");
+		return err;
 	}
 
 	platform_set_drvdata(pdev, drvdata);
 
-	dev_info(&pdev->dev, "Loongson1 Watchdog driver registered\n");
-
-	return 0;
-err0:
-	clk_disable_unprepare(drvdata->clk);
-	return err;
-}
-
-static int ls1x_wdt_remove(struct platform_device *pdev)
-{
-	struct ls1x_wdt_drvdata *drvdata = platform_get_drvdata(pdev);
-
-	watchdog_unregister_device(&drvdata->wdt);
-	clk_disable_unprepare(drvdata->clk);
+	dev_info(dev, "Loongson1 Watchdog driver registered\n");
 
 	return 0;
 }
 
 static struct platform_driver ls1x_wdt_driver = {
 	.probe = ls1x_wdt_probe,
-	.remove = ls1x_wdt_remove,
 	.driver = {
 		.name = "ls1x-wdt",
 	},