watchdog: of_xilinx_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
- 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: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/of_xilinx_wdt.c

@@ -151,41 +151,46 @@ static u32 xwdt_selftest(struct xwdt_device *xdev)
 		return XWT_TIMER_FAILED;
 }
 
+static void xwdt_clk_disable_unprepare(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
 static int xwdt_probe(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
 	int rc;
 	u32 pfreq = 0, enable_once = 0;
 	struct xwdt_device *xdev;
 	struct watchdog_device *xilinx_wdt_wdd;
 
-	xdev = devm_kzalloc(&pdev->dev, sizeof(*xdev), GFP_KERNEL);
+	xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
 	if (!xdev)
 		return -ENOMEM;
 
 	xilinx_wdt_wdd = &xdev->xilinx_wdt_wdd;
 	xilinx_wdt_wdd->info = &xilinx_wdt_ident;
 	xilinx_wdt_wdd->ops = &xilinx_wdt_ops;
-	xilinx_wdt_wdd->parent = &pdev->dev;
+	xilinx_wdt_wdd->parent = dev;
 
 	xdev->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(xdev->base))
 		return PTR_ERR(xdev->base);
 
-	rc = of_property_read_u32(pdev->dev.of_node, "xlnx,wdt-interval",
+	rc = of_property_read_u32(dev->of_node, "xlnx,wdt-interval",
 				  &xdev->wdt_interval);
 	if (rc)
-		dev_warn(&pdev->dev,
-			 "Parameter \"xlnx,wdt-interval\" not found\n");
+		dev_warn(dev, "Parameter \"xlnx,wdt-interval\" not found\n");
 
-	rc = of_property_read_u32(pdev->dev.of_node, "xlnx,wdt-enable-once",
+	rc = of_property_read_u32(dev->of_node, "xlnx,wdt-enable-once",
 				  &enable_once);
 	if (rc)
-		dev_warn(&pdev->dev,
+		dev_warn(dev,
 			 "Parameter \"xlnx,wdt-enable-once\" not found\n");
 
 	watchdog_set_nowayout(xilinx_wdt_wdd, enable_once);
 
-	xdev->clk = devm_clk_get(&pdev->dev, NULL);
+	xdev->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(xdev->clk)) {
 		if (PTR_ERR(xdev->clk) != -ENOENT)
 			return PTR_ERR(xdev->clk);
@@ -196,10 +201,10 @@ static int xwdt_probe(struct platform_device *pdev)
 		 */
 		xdev->clk = NULL;
 
-		rc = of_property_read_u32(pdev->dev.of_node, "clock-frequency",
+		rc = of_property_read_u32(dev->of_node, "clock-frequency",
 					  &pfreq);
 		if (rc)
-			dev_warn(&pdev->dev,
+			dev_warn(dev,
 				 "The watchdog clock freq cannot be obtained\n");
 	} else {
 		pfreq = clk_get_rate(xdev->clk);
@@ -218,43 +223,33 @@ static int xwdt_probe(struct platform_device *pdev)
 
 	rc = clk_prepare_enable(xdev->clk);
 	if (rc) {
-		dev_err(&pdev->dev, "unable to enable clock\n");
+		dev_err(dev, "unable to enable clock\n");
 		return rc;
 	}
+	rc = devm_add_action_or_reset(dev, xwdt_clk_disable_unprepare,
+				      xdev->clk);
+	if (rc)
+		return rc;
 
 	rc = xwdt_selftest(xdev);
 	if (rc == XWT_TIMER_FAILED) {
-		dev_err(&pdev->dev, "SelfTest routine error\n");
-		goto err_clk_disable;
+		dev_err(dev, "SelfTest routine error\n");
+		return rc;
 	}
 
-	rc = watchdog_register_device(xilinx_wdt_wdd);
+	rc = devm_watchdog_register_device(dev, xilinx_wdt_wdd);
 	if (rc) {
-		dev_err(&pdev->dev, "Cannot register watchdog (err=%d)\n", rc);
-		goto err_clk_disable;
+		dev_err(dev, "Cannot register watchdog (err=%d)\n", rc);
+		return rc;
 	}
 
 	clk_disable(xdev->clk);
 
-	dev_info(&pdev->dev, "Xilinx Watchdog Timer at %p with timeout %ds\n",
+	dev_info(dev, "Xilinx Watchdog Timer at %p with timeout %ds\n",
 		 xdev->base, xilinx_wdt_wdd->timeout);
 
 	platform_set_drvdata(pdev, xdev);
 
-	return 0;
-err_clk_disable:
-	clk_disable_unprepare(xdev->clk);
-
-	return rc;
-}
-
-static int xwdt_remove(struct platform_device *pdev)
-{
-	struct xwdt_device *xdev = platform_get_drvdata(pdev);
-
-	watchdog_unregister_device(&xdev->xilinx_wdt_wdd);
-	clk_disable_unprepare(xdev->clk);
-
 	return 0;
 }
 
@@ -303,7 +298,6 @@ MODULE_DEVICE_TABLE(of, xwdt_of_match);
 
 static struct platform_driver xwdt_driver = {
 	.probe       = xwdt_probe,
-	.remove      = xwdt_remove,
 	.driver = {
 		.name  = WATCHDOG_NAME,
 		.of_match_table = xwdt_of_match,