staging: vchiq: Refactor vchiq cdev code

Move the vchiq cdev initialization code to its own function for better
code organization. Call the initialization function during probe, thus
shifting the whole cdev creation logic (which was earlier split in
vchiq_probe() and vchiq_driver_init()) to vchiq_probe().

Reviewed-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Ojaswin Mujoo <ojaswin98@gmail.com>
Link: https://lore.kernel.org/r/c0e538eb0644292a52267d39edd85ab2af9f9a4e.1626882325.git.ojaswin98@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Ojaswin Mujoo

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c

@@ -2134,6 +2134,81 @@ vchiq_fops = {
 	.read = vchiq_read
 };
 
+/**
+ *	vchiq_register_chrdev - Register the char driver for vchiq
+ *				and create the necessary class and
+ *				device files in userspace.
+ *	@parent		The parent of the char device.
+ *
+ *	Returns 0 on success else returns the error code.
+ */
+static int vchiq_register_chrdev(struct device *parent)
+{
+	struct device *vchiq_dev;
+	int ret;
+
+	vchiq_class = class_create(THIS_MODULE, DEVICE_NAME);
+	if (IS_ERR(vchiq_class)) {
+		pr_err("Failed to create vchiq class\n");
+		ret = PTR_ERR(vchiq_class);
+		goto error_exit;
+	}
+
+	ret = alloc_chrdev_region(&vchiq_devid, 0, 1, DEVICE_NAME);
+	if (ret) {
+		pr_err("vchiq: Failed to allocate vchiq's chrdev region\n");
+		goto alloc_region_error;
+	}
+
+	cdev_init(&vchiq_cdev, &vchiq_fops);
+	vchiq_cdev.owner = THIS_MODULE;
+	ret = cdev_add(&vchiq_cdev, vchiq_devid, 1);
+	if (ret) {
+		vchiq_log_error(vchiq_arm_log_level,
+				"Unable to register vchiq char device");
+		goto cdev_add_error;
+	}
+
+	vchiq_dev = device_create(vchiq_class, parent, vchiq_devid, NULL,
+				  DEVICE_NAME);
+	if (IS_ERR(vchiq_dev)) {
+		vchiq_log_error(vchiq_arm_log_level,
+				"Failed to create vchiq char device node");
+		ret = PTR_ERR(vchiq_dev);
+		goto device_create_error;
+	}
+
+	vchiq_log_info(vchiq_arm_log_level,
+		       "vchiq char dev initialised successfully - device %d.%d",
+			MAJOR(vchiq_devid), MINOR(vchiq_devid));
+
+	return 0;
+
+device_create_error:
+	cdev_del(&vchiq_cdev);
+
+cdev_add_error:
+	unregister_chrdev_region(vchiq_devid, 1);
+
+alloc_region_error:
+	class_destroy(vchiq_class);
+
+error_exit:
+	return ret;
+}
+
+/**
+ *	vchiq_deregister_chrdev	- Deregister and cleanup the vchiq char
+ *				  driver and device files
+ */
+static void vchiq_deregister_chrdev(void)
+{
+	device_destroy(vchiq_class, vchiq_devid);
+	cdev_del(&vchiq_cdev);
+	unregister_chrdev_region(vchiq_devid, 1);
+	class_destroy(vchiq_class);
+}
+
 /*
  * Autosuspend related functionality
  */
@@ -2644,7 +2719,6 @@ static int vchiq_probe(struct platform_device *pdev)
 	struct device_node *fw_node;
 	const struct of_device_id *of_id;
 	struct vchiq_drvdata *drvdata;
-	struct device *vchiq_dev;
 	int err;
 
 	of_id = of_match_node(vchiq_of_match, pdev->dev.of_node);
@@ -2670,38 +2744,31 @@ static int vchiq_probe(struct platform_device *pdev)
 	if (err)
 		goto failed_platform_init;
 
-	cdev_init(&vchiq_cdev, &vchiq_fops);
-	vchiq_cdev.owner = THIS_MODULE;
-	err = cdev_add(&vchiq_cdev, vchiq_devid, 1);
-	if (err) {
-		vchiq_log_error(vchiq_arm_log_level,
-			"Unable to register device");
-		goto failed_platform_init;
-	}
-
-	vchiq_dev = device_create(vchiq_class, &pdev->dev, vchiq_devid, NULL,
-				  "vchiq");
-	if (IS_ERR(vchiq_dev)) {
-		err = PTR_ERR(vchiq_dev);
-		goto failed_device_create;
-	}
-
 	vchiq_debugfs_init();
 
 	vchiq_log_info(vchiq_arm_log_level,
-		"vchiq: initialised - version %d (min %d), device %d.%d",
-		VCHIQ_VERSION, VCHIQ_VERSION_MIN,
-		MAJOR(vchiq_devid), MINOR(vchiq_devid));
+		       "vchiq: platform initialised - version %d (min %d)",
+		       VCHIQ_VERSION, VCHIQ_VERSION_MIN);
+
+	/*
+	 * Simply exit on error since the function handles cleanup in
+	 * cases of failure.
+	 */
+	err = vchiq_register_chrdev(&pdev->dev);
+	if (err) {
+		vchiq_log_warning(vchiq_arm_log_level,
+				  "Failed to initialize vchiq cdev");
+		goto error_exit;
+	}
 
 	bcm2835_camera = vchiq_register_child(pdev, "bcm2835-camera");
 	bcm2835_audio = vchiq_register_child(pdev, "bcm2835_audio");
 
 	return 0;
 
-failed_device_create:
-	cdev_del(&vchiq_cdev);
 failed_platform_init:
-	vchiq_log_warning(vchiq_arm_log_level, "could not load vchiq");
+	vchiq_log_warning(vchiq_arm_log_level, "could not initialize vchiq platform");
+error_exit:
 	return err;
 }
 
@@ -2710,8 +2777,7 @@ static int vchiq_remove(struct platform_device *pdev)
 	platform_device_unregister(bcm2835_audio);
 	platform_device_unregister(bcm2835_camera);
 	vchiq_debugfs_deinit();
-	device_destroy(vchiq_class, vchiq_devid);
-	cdev_del(&vchiq_cdev);
+	vchiq_deregister_chrdev();
 
 	return 0;
 }
@@ -2729,31 +2795,9 @@ static int __init vchiq_driver_init(void)
 {
 	int ret;
 
-	vchiq_class = class_create(THIS_MODULE, DEVICE_NAME);
-	if (IS_ERR(vchiq_class)) {
-		pr_err("Failed to create vchiq class\n");
-		return PTR_ERR(vchiq_class);
-	}
-
-	ret = alloc_chrdev_region(&vchiq_devid, 0, 1, DEVICE_NAME);
-	if (ret) {
-		pr_err("Failed to allocate vchiq's chrdev region\n");
-		goto class_destroy;
-	}
-
 	ret = platform_driver_register(&vchiq_driver);
-	if (ret) {
+	if (ret)
 		pr_err("Failed to register vchiq driver\n");
-		goto region_unregister;
-	}
-
-	return 0;
-
-region_unregister:
-	unregister_chrdev_region(vchiq_devid, 1);
-
-class_destroy:
-	class_destroy(vchiq_class);
 
 	return ret;
 }
@@ -2762,8 +2806,6 @@ module_init(vchiq_driver_init);
 static void __exit vchiq_driver_exit(void)
 {
 	platform_driver_unregister(&vchiq_driver);
-	unregister_chrdev_region(vchiq_devid, 1);
-	class_destroy(vchiq_class);
 }
 module_exit(vchiq_driver_exit);