IR-Transmitter.c

/**
* @file IR-Transmitter.c
* Driver for Infrared Transmitter Sensor for RPI
* 
*/

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

#define DEVICE_NAME "ir_tr"
#define CLASS_NAME "irTR"

static int majorNumber;
int cp_cnt;
static struct class *cl = NULL;
static struct device *dev = NULL;

static unsigned gpio_irtr = 2;

static int open_init (struct inode *inodep, struct file *filep);
ssize_t write_init (struct file *filep, const char __user *buffer, size_t len, loff_t *offset);
static int release_init (struct inode *inodep, struct file *filep);

static struct file_operations fops = 
{
        .open = open_init,
        .write = write_init,
        .release = release_init,
};

static int open_init (struct inode *inodep, struct file *filep){
	
	printk (KERN_INFO "IRTR: iRTr Sensor Device Opened\n");
	return 0;
}

static int release_init (struct inode *inodep, struct file *filep){

	printk (KERN_INFO "IRTR: iRTr Sensor Device closing\n");
	return 0;
}

static int __init irtr_init (void){

	printk(KERN_INFO "IRTR: Initializing driver to IRTR sensor\n");

    majorNumber = register_chrdev (0, "irTr", &fops);

    if (majorNumber < 0){
        printk (KERN_INFO "Failed to register iRTr device file\n");
        return -EIO;
    }

    printk (KERN_INFO "IRTR: Sensor irTr registered correctly with majorNumber = %d\n", majorNumber);

	cl = class_create (THIS_MODULE, CLASS_NAME);		// class_create (THIS_MODULE, "CLASS_NAME"); // ISO C90: NO mixing in declaration 

    if (IS_ERR(cl)){

        unregister_chrdev(majorNumber, DEVICE_NAME);
        printk(KERN_ALERT "Failed to register device CLASS\n");
        return -EIO;

    }

    dev = device_create (cl, NULL, MKDEV(majorNumber, 0), NULL, DEVICE_NAME);			// device_create (CLASS, NULL, MKDEV(MajNum, 0), NULL, "DEVICE_NAME")

	if (IS_ERR(dev)){

        class_destroy (cl);
        unregister_chrdev(majorNumber, DEVICE_NAME);
        printk(KERN_ALERT "Failed to register device CLASS\n");
        return -EIO;
    }


	if(!gpio_is_valid (gpio_irtr)){
		printk (KERN_INFO "GPIO_ERR: Invalid GPIO PIN\n");
		return -ENODEV;
	}

	gpio_request (gpio_irtr, "sysfs");					//     	int gpio_request(unsigned int gpio, const char *label)
	gpio_direction_output (gpio_irtr, 0);				//		int gpio_direction_output(unsigned gpio, int value)
	gpio_export (gpio_irtr, false);						//      int gpio_export(unsigned int gpio, bool direction_may_change);
	//gpio_set_value (gpio_irtr, 1);

	return 0;
}

static void __exit irtr_exit(void){

    device_destroy (cl, MKDEV(majorNumber, 0));
    class_unregister(cl);
    class_destroy (cl);
    unregister_chrdev(majorNumber, DEVICE_NAME);
    printk (KERN_INFO "Clearing the iRTr sensor driver\n");

}

char irtr_st[2];

ssize_t write_init (struct file *filep, const char __user *buffer, size_t len, loff_t *offset){

	cp_cnt = copy_from_user (irtr_st, buffer, sizeof(irtr_st));

	if (irtr_st[0] == '1'){
		gpio_set_value (gpio_irtr, 1);
	}
	else if (irtr_st[0] == '0'){
		gpio_set_value (gpio_irtr, 0);
	}
    if(cp_cnt == 0){

        printk (KERN_INFO "Something written from USER_SPACE\n");
        return 0;
    }

    else{
        printk (KERN_INFO "Failed to data transfer from space->(KERN 2 USER)\n");
        return -EFAULT;
    }

	return 0;
}

module_init (irtr_init);
module_exit (irtr_exit);

MODULE_LICENSE ("GPL");
MODULE_AUTHOR ("-Rafiq-");
MODULE_DESCRIPTION ("Infrared Transmitter Kmod");
MODULE_VERSION ("0.1");

Makefile

obj-m := IR-Transmitter.o

all:
	make -C /lib/modules/$(shell uname -r)/build/ M=$(shell pwd) modules

clean:
	make -C /lib/modules/$(shell uname -r)/build/ M=$(shell pwd) clean

U_irtr.c

/**
* @file U_irtr.c
* User program for Infrared Transmitter Sensor
*/

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>

int main(){

	char *sen_st;
	int fd;
	fd = open ("/dev/ir_tr", O_RDWR);
	while (1){
		sen_st = "1";
		write (fd, sen_st, 1);
		sleep (1);
		sen_st = "0";
		write (fd, sen_st, 1);
		sleep (1);
	}
	close (fd);
	return 0;

}