watchdog: stm32_iwdg: 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: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/stm32_iwdg.c

@@ -138,38 +138,52 @@ static int stm32_iwdg_set_timeout(struct watchdog_device *wdd,
 	return 0;
 }
 
+static void stm32_clk_disable_unprepare(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
 static int stm32_iwdg_clk_init(struct platform_device *pdev,
 			       struct stm32_iwdg *wdt)
 {
+	struct device *dev = &pdev->dev;
 	u32 ret;
 
-	wdt->clk_lsi = devm_clk_get(&pdev->dev, "lsi");
+	wdt->clk_lsi = devm_clk_get(dev, "lsi");
 	if (IS_ERR(wdt->clk_lsi)) {
-		dev_err(&pdev->dev, "Unable to get lsi clock\n");
+		dev_err(dev, "Unable to get lsi clock\n");
 		return PTR_ERR(wdt->clk_lsi);
 	}
 
 	/* optional peripheral clock */
 	if (wdt->has_pclk) {
-		wdt->clk_pclk = devm_clk_get(&pdev->dev, "pclk");
+		wdt->clk_pclk = devm_clk_get(dev, "pclk");
 		if (IS_ERR(wdt->clk_pclk)) {
-			dev_err(&pdev->dev, "Unable to get pclk clock\n");
+			dev_err(dev, "Unable to get pclk clock\n");
 			return PTR_ERR(wdt->clk_pclk);
 		}
 
 		ret = clk_prepare_enable(wdt->clk_pclk);
 		if (ret) {
-			dev_err(&pdev->dev, "Unable to prepare pclk clock\n");
+			dev_err(dev, "Unable to prepare pclk clock\n");
 			return ret;
 		}
+		ret = devm_add_action_or_reset(dev,
+					       stm32_clk_disable_unprepare,
+					       wdt->clk_pclk);
+		if (ret)
+			return ret;
 	}
 
 	ret = clk_prepare_enable(wdt->clk_lsi);
 	if (ret) {
-		dev_err(&pdev->dev, "Unable to prepare lsi clock\n");
-		clk_disable_unprepare(wdt->clk_pclk);
+		dev_err(dev, "Unable to prepare lsi clock\n");
 		return ret;
 	}
+	ret = devm_add_action_or_reset(dev, stm32_clk_disable_unprepare,
+				       wdt->clk_lsi);
+	if (ret)
+		return ret;
 
 	wdt->rate = clk_get_rate(wdt->clk_lsi);
 
@@ -199,16 +213,17 @@ MODULE_DEVICE_TABLE(of, stm32_iwdg_of_match);
 
 static int stm32_iwdg_probe(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
 	struct watchdog_device *wdd;
 	const struct of_device_id *match;
 	struct stm32_iwdg *wdt;
 	int ret;
 
-	match = of_match_device(stm32_iwdg_of_match, &pdev->dev);
+	match = of_match_device(stm32_iwdg_of_match, dev);
 	if (!match)
 		return -ENODEV;
 
-	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 	if (!wdt)
 		return -ENOMEM;
 
@@ -217,7 +232,7 @@ static int stm32_iwdg_probe(struct platform_device *pdev)
 	/* This is the timer base. */
 	wdt->regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(wdt->regs)) {
-		dev_err(&pdev->dev, "Could not get resource\n");
+		dev_err(dev, "Could not get resource\n");
 		return PTR_ERR(wdt->regs);
 	}
 
@@ -231,46 +246,28 @@ static int stm32_iwdg_probe(struct platform_device *pdev)
 	wdd->ops = &stm32_iwdg_ops;
 	wdd->min_timeout = ((RLR_MIN + 1) * 256) / wdt->rate;
 	wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * 256 * 1000) / wdt->rate;
-	wdd->parent = &pdev->dev;
+	wdd->parent = dev;
 
 	watchdog_set_drvdata(wdd, wdt);
 	watchdog_set_nowayout(wdd, WATCHDOG_NOWAYOUT);
 
-	ret = watchdog_init_timeout(wdd, 0, &pdev->dev);
+	ret = watchdog_init_timeout(wdd, 0, dev);
 	if (ret)
-		dev_warn(&pdev->dev,
-			 "unable to set timeout value, using default\n");
+		dev_warn(dev, "unable to set timeout value, using default\n");
 
-	ret = watchdog_register_device(wdd);
+	ret = devm_watchdog_register_device(dev, wdd);
 	if (ret) {
-		dev_err(&pdev->dev, "failed to register watchdog device\n");
-		goto err;
+		dev_err(dev, "failed to register watchdog device\n");
+		return ret;
 	}
 
 	platform_set_drvdata(pdev, wdt);
 
-	return 0;
-err:
-	clk_disable_unprepare(wdt->clk_lsi);
-	clk_disable_unprepare(wdt->clk_pclk);
-
-	return ret;
-}
-
-static int stm32_iwdg_remove(struct platform_device *pdev)
-{
-	struct stm32_iwdg *wdt = platform_get_drvdata(pdev);
-
-	watchdog_unregister_device(&wdt->wdd);
-	clk_disable_unprepare(wdt->clk_lsi);
-	clk_disable_unprepare(wdt->clk_pclk);
-
 	return 0;
 }
 
 static struct platform_driver stm32_iwdg_driver = {
 	.probe		= stm32_iwdg_probe,
-	.remove		= stm32_iwdg_remove,
 	.driver = {
 		.name	= "iwdg",
 		.of_match_table = of_match_ptr(stm32_iwdg_of_match),