watchdog: atlas7_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
- Replace 'of_clk_get(np, 0)' with 'devm_clk_get(dev, NULL)'
- Introduce local variable 'struct device *dev' and use it instead of
  dereferencing it repeatedly
- Use devm_watchdog_register_driver() to register watchdog device
- Replace shutdown function with call to watchdog_stop_on_reboot()

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

drivers/watchdog/atlas7_wdt.c

@@ -125,78 +125,57 @@ static const struct of_device_id atlas7_wdt_ids[] = {
 	{}
 };
 
+static void atlas7_clk_disable_unprepare(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
 static int atlas7_wdt_probe(struct platform_device *pdev)
 {
-	struct device_node *np = pdev->dev.of_node;
+	struct device *dev = &pdev->dev;
 	struct atlas7_wdog *wdt;
 	struct clk *clk;
 	int ret;
 
-	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 	if (!wdt)
 		return -ENOMEM;
 	wdt->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(wdt->base))
 		return PTR_ERR(wdt->base);
 
-	clk = of_clk_get(np, 0);
+	clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(clk))
 		return PTR_ERR(clk);
 	ret = clk_prepare_enable(clk);
 	if (ret) {
-		dev_err(&pdev->dev, "clk enable failed\n");
-		goto err;
+		dev_err(dev, "clk enable failed\n");
+		return ret;
 	}
+	ret = devm_add_action_or_reset(dev, atlas7_clk_disable_unprepare, clk);
+	if (ret)
+		return ret;
 
 	/* disable watchdog hardware */
 	writel(0, wdt->base + ATLAS7_WDT_CNT_CTRL);
 
 	wdt->tick_rate = clk_get_rate(clk);
-	if (!wdt->tick_rate) {
-		ret = -EINVAL;
-		goto err1;
-	}
+	if (!wdt->tick_rate)
+		return -EINVAL;
 
 	wdt->clk = clk;
 	atlas7_wdd.min_timeout = 1;
 	atlas7_wdd.max_timeout = UINT_MAX / wdt->tick_rate;
 
-	watchdog_init_timeout(&atlas7_wdd, 0, &pdev->dev);
+	watchdog_init_timeout(&atlas7_wdd, 0, dev);
 	watchdog_set_nowayout(&atlas7_wdd, nowayout);
 
 	watchdog_set_drvdata(&atlas7_wdd, wdt);
 	platform_set_drvdata(pdev, &atlas7_wdd);
 
-	ret = watchdog_register_device(&atlas7_wdd);
-	if (ret)
-		goto err1;
-
-	return 0;
-
-err1:
-	clk_disable_unprepare(clk);
-err:
-	clk_put(clk);
-	return ret;
-}
-
-static void atlas7_wdt_shutdown(struct platform_device *pdev)
-{
-	struct watchdog_device *wdd = platform_get_drvdata(pdev);
-	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
-
-	atlas7_wdt_disable(wdd);
-	clk_disable_unprepare(wdt->clk);
-}
-
-static int atlas7_wdt_remove(struct platform_device *pdev)
-{
-	struct watchdog_device *wdd = platform_get_drvdata(pdev);
-	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
-
-	atlas7_wdt_shutdown(pdev);
-	clk_put(wdt->clk);
-	return 0;
+	watchdog_stop_on_reboot(&atlas7_wdd);
+	watchdog_stop_on_unregister(&atlas7_wdd);
+	return devm_watchdog_register_device(dev, &atlas7_wdd);
 }
 
 static int __maybe_unused atlas7_wdt_suspend(struct device *dev)
@@ -234,8 +213,6 @@ static struct platform_driver atlas7_wdt_driver = {
 		.of_match_table	= atlas7_wdt_ids,
 	},
 	.probe = atlas7_wdt_probe,
-	.remove = atlas7_wdt_remove,
-	.shutdown = atlas7_wdt_shutdown,
 };
 module_platform_driver(atlas7_wdt_driver);