#include <linux/module.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/gpio.h>

// Operation prototypes
static int dev_open(struct inode *, struct file *);

int major;
struct class *j_class;
struct device *j_device;

// The driver's file operations
static const struct file_operations fops = {
	.owner = THIS_MODULE,
	.open = dev_open
};

/**
 * Driver initialization code. 
 */
static int __init mylab1_joystick_dev_init(void) {
	// TODO
	// 1) Register the device by dynamically obtaining a major number
    major = register_chrdev(0, "mylab1_joystick", &fops);
    if(major < 0){
        pr_info("mylab1_joystick: could not get a major number, initialisation failed\n");
        return -1;
    }
	// 2) Create the class
    j_class = class_create("mylab1_joystick");
    if (IS_ERR(j_class)){
        pr_info("mylab1_joystick: could not create class, initialisation failed\n");
        return -1;
    }
    // 3) Create the device in /dev
    j_device = device_create(j_class, NULL, MKDEV(major, 0), NULL, "mylab1_joystick");
    if (IS_ERR(j_device)){
        pr_info("mylab1_joystick: could not create device, initialisation failed\n");
        return -1;
    }
	// 6) Request the necessary GPIOs
	// 7) Register an IRQ handler per GPIO
	pr_info("mylab1_joystick: driver initialized\n");
	return 0;
}

/**
 * This function is called when the module is unloaded.
 */
static void __exit mylab1_joystick_dev_exit(void) {
	// TODO
	// 1) Destroy the device
    device_destroy(j_class,MKDEV(major, 0));
	// 2) Destroy the class
    class_destroy(j_class);
	// 4) Unregister the device
    unregister_chrdev(major,"mylab1_joystick");
	// 5) Free the IRQs
	// 6) Free the GPIOs
	pr_info("mylab1_joystick: driver destroyed\n");
}

/**
 * Open operation
 */
static int dev_open(struct inode *inod, struct file *f) {
	pr_info("mylab1_joystick: device opened\n");
	return 0;
}

/**
 * Joystick left IRQ handler
 */
/*
static irqreturn_t mylab_left_irq_handler(int irq, void *dev_id) {
	// TODO
	// - Operations to be done when the left position of the joystick is triggered
    // - At minimum, the joystick state must be updated
	return (irqreturn_t) IRQ_HANDLED;  // Announce that the IRQ has been handled correctly
}
*/

module_init(mylab1_joystick_dev_init);
module_exit(mylab1_joystick_dev_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jaime Coder <maxime.rohmer@hesge.ch>");
MODULE_DESCRIPTION("Module to drive the joystick on the myLab1 card");
MODULE_VERSION("0.1");