#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/gpio.h>
#include <asm/uaccess.h>
#define DEVICE_NAME "gpiomod"


// MODULE ATRIBUTES
MODULE_LICENSE("GPL");
MODULE_AUTHOR("VPenkoff");
MODULE_DESCRIPTION("GPIO mod");

//Global Vars
static int Major;

// Function Declarations
int gpiomod_open(struct inode *inode, struct file *filp);
int gpiomod_release(struct inode *inode, struct file *filp);
ssize_t gpiomod_read(struct file *filp, char *buf, size_t count, loff_t *f_pos);
ssize_t gpiomod_write( struct file *filp, const char *buf, size_t count, loff_t *f_p$


// File Operations
struct file_operations gpiomod_fops = {
        .open = gpiomod_open,
        .write = gpiomod_write,
        .read = gpiomod_read,
        .release = gpiomod_release
};


// module load
static int gpiomod_init(void) {
        Major = register_chrdev(222, DEVICE_NAME, &gpiomod_fops); 
        if (Major<0){
                printk(KERN_ALERT "Device registration failed...\n");
                return -ENODEV;
        } else {
                printk(KERN_ALERT "Deivce registered...\n");
        }
        return Major;
}


// Method: Open
int gpiomod_open(struct inode *inode, struct file *filp) {

        gpio_is_valid(42);
        gpio_request(42, "gpiomod");
        gpio_direction_output(42, 1);
        gpio_set_value(42, 1);
        gpio_export(42, true);
        return 0;
}

// Method: Release

int gpiomod_release(struct inode *inode, struct file *filp) {

        gpio_free(42);
        return 0;
}

// Method: Write
ssize_t gpiomod_write( struct file *filp, const char *buf, size_t count, loff_t *f_p$
       
        const char *tmp;
        char gpiomod_buffer;
        tmp=buf+count-1;
        copy_from_user(&gpiomod_buffer, tmp, 1);
        return 1;
}
// Method: Read

ssize_t gpiomod_read(struct file *filp, char *buf, size_t count, loff_t *f_pos) {

        char gpiomod_buffer;
        copy_to_user(buf, &gpiomod_buffer, 1);
        if (*f_pos == 0) {
                *f_pos+=1;
                return 1;
        } else {
                return 0;
        }
}

module_init(gpiomod_init);
module_exit(gpiomod_exit);