Device node creation without using "mknod"

#include "linux/kernel.h"
#include "linux/module.h"
#include "linux/init.h"
#include "linux/platform_device.h"
#include "linux/gpio.h"
#include "linux/fs.h"
#include "linux/errno.h"
#include "asm/uaccess.h"
#include "linux/version.h"
#include "linux/types.h"
#include "linux/kdev_t.h"
#include "linux/device.h"
#include "linux/cdev.h"

#define GPIO_NUMBER    149     //User LED 0. GPIO number 149. Page 71 of BB-xM Sys Ref Manual.

static dev_t first;         // Global variable for the first device number
static struct cdev c_dev;     // Global variable for the character device structure
static struct class *cl;     // Global variable for the device class

static int init_result;

static ssize_t gpio_read( struct file* F, char *buf, size_t count, loff_t *f_pos )
{
    char buffer[10];

    int temp = gpio_get_value(GPIO_NUMBER);

    sprintf( buffer, "%1d" , temp );

    count = sizeof( buffer );

    if( copy_to_user( buf, buffer, count ) )
    {
        return -EFAULT;
    }

    if( *f_pos == 0 )
    {
        *f_pos += 1;
        return 1;
    }
    else
    {
        return 0;
    }
}

static ssize_t gpio_write( struct file* F, const char *buf, size_t count, loff_t *f_pos )
{

    printk(KERN_INFO "Executing WRITE.\n");

    switch( buf[0] )
    {
        case '0':
        gpio_set_value(GPIO_NUMBER, 0);
        break;

        case '1':
        gpio_set_value(GPIO_NUMBER, 1);
        break;

        default:
        printk("Wrong option.\n");
        break;
    }
    return count;
}

static int gpio_open( struct inode *inode, struct file *file )
{
    return 0;
}

static int gpio_close( struct inode *inode, struct file *file )
{
    return 0;
}

static struct file_operations FileOps =
{
    .owner        = THIS_MODULE,
    .open         = gpio_open,
    .read         = gpio_read,
    .write        = gpio_write,
    .release      = gpio_close,
};

static int init_gpio(void)
{
    //init_result = register_chrdev( 0, "gpio", &FileOps );

    init_result = alloc_chrdev_region( &first, 0, 1, "gpio_drv" );

    if( 0 > init_result )
    {
        printk( KERN_ALERT "Device Registration failed\n" );
        return -1;
    }
    //else
    //{
    //    printk( KERN_ALERT "Major number is: %d\n",init_result );
    //    return 0;
    //}

    if ( (cl = class_create( THIS_MODULE, "chardev" ) ) == NULL )
    {
        printk( KERN_ALERT "Class creation failed\n" );
        unregister_chrdev_region( first, 1 );
        return -1;
    }

    if( device_create( cl, NULL, first, NULL, "gpio_drv" ) == NULL )
    {
        printk( KERN_ALERT "Device creation failed\n" );
        class_destroy(cl);
        unregister_chrdev_region( first, 1 );
        return -1;
    }

    cdev_init( &c_dev, &FileOps );

    if( cdev_add( &c_dev, first, 1 ) == -1)
    {
        printk( KERN_ALERT "Device addition failed\n" );
        device_destroy( cl, first );
        class_destroy( cl );
        unregister_chrdev_region( first, 1 );
        return -1;
    }

    return 0;
}

void cleanup_gpio(void)
{
    //unregister_chrdev( init_result, "gpio" );

    cdev_del( &c_dev );
    device_destroy( cl, first );
    class_destroy( cl );
    unregister_chrdev_region( first, 1 );

    printk(KERN_ALERT "Device unregistered\n");
}

module_init(init_gpio);
module_exit(cleanup_gpio);

MODULE_AUTHOR("Sanchayan");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Beagleboard-xM GPIO Driver");

#include "stdio.h"
#include "fcntl.h"

int main(void)
{
    int fd;
    char gpio_buffer[10];
    char choice[10];

    fd = open( "/dev/gpio_drv", O_RDWR );

    printf( "Value of fd is: %d", fd );

    if( fd < 0 )
    {
        printf("Cannot open device \t");
        printf(" fd = %d \n",fd);
        return 0;
     }

     printf("\nPlease enter choice: \t");
     scanf( "%s", choice );
     printf("Your choice is: %s \n", choice );
     write( fd, choice, 1 );
     read( fd, gpio_buffer, 1);
     printf("GPIO value is: %s \n", gpio_buffer );

     if( 0 != close(fd) )
     {
         printf("Could not close device\n");
     }

     return 0;
}

arm-none-linux-gnueabi-gcc gpio_app.c -o gpio_app