watchdog: Create watchdog device in watchdog_dev.c

The watchdog character device is currently created in watchdog_dev.c,
and the watchdog device in watchdog_core.c. This results in
cross-dependencies, since device creation needs to know the watchdog
character device number as well as the watchdog class, both of which
reside in watchdog_dev.c.

Create the watchdog device in watchdog_dev.c to simplify the code.

Inspired by earlier patch set from Damien Riegel.

Cc: Damien Riegel <damien.riegel@savoirfairelinux.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/watchdog_core.c

@@ -42,7 +42,6 @@
 #include "watchdog_core.h"	/* For watchdog_dev_register/... */
 
 static DEFINE_IDA(watchdog_ida);
-static struct class *watchdog_class;
 
 /*
  * Deferred Registration infrastructure.
@@ -194,7 +193,7 @@ EXPORT_SYMBOL_GPL(watchdog_set_restart_priority);
 
 static int __watchdog_register_device(struct watchdog_device *wdd)
 {
-	int ret, id = -1, devno;
+	int ret, id = -1;
 
 	if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
 		return -EINVAL;
@@ -247,16 +246,6 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
 		}
 	}
 
-	devno = wdd->cdev.dev;
-	wdd->dev = device_create(watchdog_class, wdd->parent, devno,
-					wdd, "watchdog%d", wdd->id);
-	if (IS_ERR(wdd->dev)) {
-		watchdog_dev_unregister(wdd);
-		ida_simple_remove(&watchdog_ida, id);
-		ret = PTR_ERR(wdd->dev);
-		return ret;
-	}
-
 	if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
 		wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
 
@@ -265,9 +254,7 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
 			dev_err(wdd->dev, "Cannot register reboot notifier (%d)\n",
 				ret);
 			watchdog_dev_unregister(wdd);
-			device_destroy(watchdog_class, devno);
 			ida_simple_remove(&watchdog_ida, wdd->id);
-			wdd->dev = NULL;
 			return ret;
 		}
 	}
@@ -311,9 +298,6 @@ EXPORT_SYMBOL_GPL(watchdog_register_device);
 
 static void __watchdog_unregister_device(struct watchdog_device *wdd)
 {
-	int ret;
-	int devno;
-
 	if (wdd == NULL)
 		return;
 
@@ -323,13 +307,8 @@ static void __watchdog_unregister_device(struct watchdog_device *wdd)
 	if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status))
 		unregister_reboot_notifier(&wdd->reboot_nb);
 
-	devno = wdd->cdev.dev;
-	ret = watchdog_dev_unregister(wdd);
-	if (ret)
-		pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
-	device_destroy(watchdog_class, devno);
+	watchdog_dev_unregister(wdd);
 	ida_simple_remove(&watchdog_ida, wdd->id);
-	wdd->dev = NULL;
 }
 
 /**
@@ -370,9 +349,11 @@ static int __init watchdog_deferred_registration(void)
 
 static int __init watchdog_init(void)
 {
-	watchdog_class = watchdog_dev_init();
-	if (IS_ERR(watchdog_class))
-		return PTR_ERR(watchdog_class);
+	int err;
+
+	err = watchdog_dev_init();
+	if (err < 0)
+		return err;
 
 	watchdog_deferred_registration();
 	return 0;

drivers/watchdog/watchdog_core.h

@@ -32,6 +32,6 @@
  *	Functions/procedures to be called by the core
  */
 extern int watchdog_dev_register(struct watchdog_device *);
-extern int watchdog_dev_unregister(struct watchdog_device *);
-extern struct class * __init watchdog_dev_init(void);
+extern void watchdog_dev_unregister(struct watchdog_device *);
+extern int __init watchdog_dev_init(void);
 extern void __exit watchdog_dev_exit(void);

drivers/watchdog/watchdog_dev.c

@@ -628,17 +628,18 @@ static struct miscdevice watchdog_miscdev = {
 };
 
 /*
- *	watchdog_dev_register: register a watchdog device
+ *	watchdog_cdev_register: register watchdog character device
  *	@wdd: watchdog device
+ *	@devno: character device number
  *
- *	Register a watchdog device including handling the legacy
+ *	Register a watchdog character device including handling the legacy
  *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
  *	thus we set it up like that.
  */
 
-int watchdog_dev_register(struct watchdog_device *wdd)
+static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
 {
-	int err, devno;
+	int err;
 
 	if (wdd->id == 0) {
 		old_wdd = wdd;
@@ -656,7 +657,6 @@ int watchdog_dev_register(struct watchdog_device *wdd)
 	}
 
 	/* Fill in the data structures */
-	devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
 	cdev_init(&wdd->cdev, &watchdog_fops);
 	wdd->cdev.owner = wdd->ops->owner;
 
@@ -674,13 +674,14 @@ int watchdog_dev_register(struct watchdog_device *wdd)
 }
 
 /*
- *	watchdog_dev_unregister: unregister a watchdog device
+ *	watchdog_cdev_unregister: unregister watchdog character device
  *	@watchdog: watchdog device
  *
- *	Unregister the watchdog and if needed the legacy /dev/watchdog device.
+ *	Unregister watchdog character device and if needed the legacy
+ *	/dev/watchdog device.
  */
 
-int watchdog_dev_unregister(struct watchdog_device *wdd)
+static void watchdog_cdev_unregister(struct watchdog_device *wdd)
 {
 	mutex_lock(&wdd->lock);
 	set_bit(WDOG_UNREGISTERED, &wdd->status);
@@ -691,7 +692,6 @@ int watchdog_dev_unregister(struct watchdog_device *wdd)
 		misc_deregister(&watchdog_miscdev);
 		old_wdd = NULL;
 	}
-	return 0;
 }
 
 static struct class watchdog_class = {
@@ -700,30 +700,77 @@ static struct class watchdog_class = {
 	.dev_groups =	wdt_groups,
 };
 
+/*
+ *	watchdog_dev_register: register a watchdog device
+ *	@wdd: watchdog device
+ *
+ *	Register a watchdog device including handling the legacy
+ *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
+ *	thus we set it up like that.
+ */
+
+int watchdog_dev_register(struct watchdog_device *wdd)
+{
+	struct device *dev;
+	dev_t devno;
+	int ret;
+
+	devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
+
+	ret = watchdog_cdev_register(wdd, devno);
+	if (ret)
+		return ret;
+
+	dev = device_create(&watchdog_class, wdd->parent, devno, wdd,
+			    "watchdog%d", wdd->id);
+	if (IS_ERR(dev)) {
+		watchdog_cdev_unregister(wdd);
+		return PTR_ERR(dev);
+	}
+	wdd->dev = dev;
+
+	return ret;
+}
+
+/*
+ *	watchdog_dev_unregister: unregister a watchdog device
+ *	@watchdog: watchdog device
+ *
+ *	Unregister watchdog device and if needed the legacy
+ *	/dev/watchdog device.
+ */
+
+void watchdog_dev_unregister(struct watchdog_device *wdd)
+{
+	watchdog_cdev_unregister(wdd);
+	device_destroy(&watchdog_class, wdd->dev->devt);
+	wdd->dev = NULL;
+}
+
 /*
  *	watchdog_dev_init: init dev part of watchdog core
  *
  *	Allocate a range of chardev nodes to use for watchdog devices
  */
 
-struct class * __init watchdog_dev_init(void)
+int __init watchdog_dev_init(void)
 {
 	int err;
 
 	err = class_register(&watchdog_class);
 	if (err < 0) {
 		pr_err("couldn't register class\n");
-		return ERR_PTR(err);
+		return err;
 	}
 
 	err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
 	if (err < 0) {
 		pr_err("watchdog: unable to allocate char dev region\n");
 		class_unregister(&watchdog_class);
-		return ERR_PTR(err);
+		return err;
 	}
 
-	return &watchdog_class;
+	return 0;
 }
 
 /*