// SPDX-License-Identifier: GPL-2.0

#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>

static int major;

static ssize_t my_read (struct file *f, char __user *u, size_t l, loff_t *o)
{
	pr_info("hello_cdev - Read is called");
	return 0;
}



static struct file_operations fops = {
	.read = my_read
};

/**
 * @brief This function is called when the module is loaded into the kernel
 */
static int __init my_init(void)
{
	/**
	 * First argument 0 auto allocates major device number
	 * returns device number
	 * Enter a number eg 64 to allocate all minor num 0 - 255
	 * 0 returned if successfull
	 */

	major = register_chrdev(0, "hello_cdev", &fops);
	if (major < 0)
	{
		pr_err("hello_cdev - Error registering chrdev\n");
		return major;
	}
	pr_info("hello_cdev - Major device number: %d\n", major);
	return 0;
}

/**
 * @brief This function is called when the module is removed from the kernel
 */
static void __exit my_exit(void)
{
	pr_info("Goodbye, Kernel\n");
	unregister_chrdev(major, "hello_cdev");
}

module_init(my_init);
module_exit(my_exit);

/* Meta Information */
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("David D'Ulisse");
MODULE_DESCRIPTION("A simple character device driver");