watchdog: st_lpc_wdt: Convert to use device managed functions

Use device managed functions to simplify error handling, reduce
source code size, improve readability, and reduce the likelyhood of bugs.

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
- Introduce local variable 'struct device *dev' and use it instead of
dereferencing it repeatedly
- Use devm_watchdog_register_driver() to register watchdog device

Cc: Patrice Chotard <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>
Acked-by: Patrice Chotard <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>

drivers/watchdog/st_lpc_wdt.c

···
 	.ops		= &st_wdog_ops,
 };
 
+static void st_clk_disable_unprepare(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
 static int st_wdog_probe(struct platform_device *pdev)
 {
+	struct device *dev = &pdev->dev;
 	const struct of_device_id *match;
-	struct device_node *np = pdev->dev.of_node;
+	struct device_node *np = dev->of_node;
 	struct st_wdog *st_wdog;
 	struct regmap *regmap;
 	struct clk *clk;
···
 
 	ret = of_property_read_u32(np, "st,lpc-mode", &mode);
 	if (ret) {
-		dev_err(&pdev->dev, "An LPC mode must be provided\n");
+		dev_err(dev, "An LPC mode must be provided\n");
 		return -EINVAL;
 	}
 
···
 	if (mode != ST_LPC_MODE_WDT)
 		return -ENODEV;
 
-	st_wdog = devm_kzalloc(&pdev->dev, sizeof(*st_wdog), GFP_KERNEL);
+	st_wdog = devm_kzalloc(dev, sizeof(*st_wdog), GFP_KERNEL);
 	if (!st_wdog)
 		return -ENOMEM;
 
-	match = of_match_device(st_wdog_match, &pdev->dev);
+	match = of_match_device(st_wdog_match, dev);
 	if (!match) {
-		dev_err(&pdev->dev, "Couldn't match device\n");
+		dev_err(dev, "Couldn't match device\n");
 		return -ENODEV;
 	}
 	st_wdog->syscfg	= (struct st_wdog_syscfg *)match->data;
···
 
 	regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
 	if (IS_ERR(regmap)) {
-		dev_err(&pdev->dev, "No syscfg phandle specified\n");
+		dev_err(dev, "No syscfg phandle specified\n");
 		return PTR_ERR(regmap);
 	}
 
-	clk = devm_clk_get(&pdev->dev, NULL);
+	clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(clk)) {
-		dev_err(&pdev->dev, "Unable to request clock\n");
+		dev_err(dev, "Unable to request clock\n");
 		return PTR_ERR(clk);
 	}
 
-	st_wdog->dev		= &pdev->dev;
+	st_wdog->dev		= dev;
 	st_wdog->base		= base;
 	st_wdog->clk		= clk;
 	st_wdog->regmap		= regmap;
···
 	st_wdog->clkrate	= clk_get_rate(st_wdog->clk);
 
 	if (!st_wdog->clkrate) {
-		dev_err(&pdev->dev, "Unable to fetch clock rate\n");
+		dev_err(dev, "Unable to fetch clock rate\n");
 		return -EINVAL;
 	}
 	st_wdog_dev.max_timeout = 0xFFFFFFFF / st_wdog->clkrate;
-	st_wdog_dev.parent = &pdev->dev;
+	st_wdog_dev.parent = dev;
 
 	ret = clk_prepare_enable(clk);
 	if (ret) {
-		dev_err(&pdev->dev, "Unable to enable clock\n");
+		dev_err(dev, "Unable to enable clock\n");
 		return ret;
 	}
+	ret = devm_add_action_or_reset(dev, st_clk_disable_unprepare, clk);
+	if (ret)
+		return ret;
 
 	watchdog_set_drvdata(&st_wdog_dev, st_wdog);
 	watchdog_set_nowayout(&st_wdog_dev, WATCHDOG_NOWAYOUT);
 
 	/* Init Watchdog timeout with value in DT */
-	ret = watchdog_init_timeout(&st_wdog_dev, 0, &pdev->dev);
+	ret = watchdog_init_timeout(&st_wdog_dev, 0, dev);
 	if (ret) {
-		dev_err(&pdev->dev, "Unable to initialise watchdog timeout\n");
-		clk_disable_unprepare(clk);
+		dev_err(dev, "Unable to initialise watchdog timeout\n");
 		return ret;
 	}
 
-	ret = watchdog_register_device(&st_wdog_dev);
+	ret = devm_watchdog_register_device(dev, &st_wdog_dev);
 	if (ret) {
-		dev_err(&pdev->dev, "Unable to register watchdog\n");
-		clk_disable_unprepare(clk);
+		dev_err(dev, "Unable to register watchdog\n");
 		return ret;
 	}
 
 	st_wdog_setup(st_wdog, true);
 
-	dev_info(&pdev->dev, "LPC Watchdog driver registered, reset type is %s",
+	dev_info(dev, "LPC Watchdog driver registered, reset type is %s",
 		 st_wdog->warm_reset ? "warm" : "cold");
 
 	return ret;
···
 	struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
 
 	st_wdog_setup(st_wdog, false);
-	watchdog_unregister_device(&st_wdog_dev);
-	clk_disable_unprepare(st_wdog->clk);
 
 	return 0;
 }