watchdog: pic32-dmt: 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
- 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
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/pic32-dmt.c

@@ -168,13 +168,19 @@ static struct watchdog_device pic32_dmt_wdd = {
 	.ops		= &pic32_dmt_fops,
 };
 
+static void pic32_clk_disable_unprepare(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
 static int pic32_dmt_probe(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
 	int ret;
 	struct pic32_dmt *dmt;
 	struct watchdog_device *wdd = &pic32_dmt_wdd;
 
-	dmt = devm_kzalloc(&pdev->dev, sizeof(*dmt), GFP_KERNEL);
+	dmt = devm_kzalloc(dev, sizeof(*dmt), GFP_KERNEL);
 	if (!dmt)
 		return -ENOMEM;
 
@@ -182,54 +188,41 @@ static int pic32_dmt_probe(struct platform_device *pdev)
 	if (IS_ERR(dmt->regs))
 		return PTR_ERR(dmt->regs);
 
-	dmt->clk = devm_clk_get(&pdev->dev, NULL);
+	dmt->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(dmt->clk)) {
-		dev_err(&pdev->dev, "clk not found\n");
+		dev_err(dev, "clk not found\n");
 		return PTR_ERR(dmt->clk);
 	}
 
 	ret = clk_prepare_enable(dmt->clk);
 	if (ret)
 		return ret;
+	ret = devm_add_action_or_reset(dev, pic32_clk_disable_unprepare,
+				       dmt->clk);
+	if (ret)
+		return ret;
 
 	wdd->timeout = pic32_dmt_get_timeout_secs(dmt);
 	if (!wdd->timeout) {
-		dev_err(&pdev->dev,
-			"failed to read watchdog register timeout\n");
-		ret = -EINVAL;
-		goto out_disable_clk;
+		dev_err(dev, "failed to read watchdog register timeout\n");
+		return -EINVAL;
 	}
 
-	dev_info(&pdev->dev, "timeout %d\n", wdd->timeout);
+	dev_info(dev, "timeout %d\n", wdd->timeout);
 
 	wdd->bootstatus = pic32_dmt_bootstatus(dmt) ? WDIOF_CARDRESET : 0;
 
 	watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT);
 	watchdog_set_drvdata(wdd, dmt);
 
-	ret = watchdog_register_device(wdd);
+	ret = devm_watchdog_register_device(dev, wdd);
 	if (ret) {
-		dev_err(&pdev->dev, "watchdog register failed, err %d\n", ret);
-		goto out_disable_clk;
+		dev_err(dev, "watchdog register failed, err %d\n", ret);
+		return ret;
 	}
 
 	platform_set_drvdata(pdev, wdd);
 	return 0;
-
-out_disable_clk:
-	clk_disable_unprepare(dmt->clk);
-	return ret;
-}
-
-static int pic32_dmt_remove(struct platform_device *pdev)
-{
-	struct watchdog_device *wdd = platform_get_drvdata(pdev);
-	struct pic32_dmt *dmt = watchdog_get_drvdata(wdd);
-
-	watchdog_unregister_device(wdd);
-	clk_disable_unprepare(dmt->clk);
-
-	return 0;
 }
 
 static const struct of_device_id pic32_dmt_of_ids[] = {
@@ -240,7 +233,6 @@ MODULE_DEVICE_TABLE(of, pic32_dmt_of_ids);
 
 static struct platform_driver pic32_dmt_driver = {
 	.probe		= pic32_dmt_probe,
-	.remove		= pic32_dmt_remove,
 	.driver		= {
 		.name		= "pic32-dmt",
 		.of_match_table = of_match_ptr(pic32_dmt_of_ids),