#include <linux/module.h>
#include <linux/version.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/kdev_t.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <asm/uaccess.h>
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 my_open(struct inode *i, struct file *f)
{
 printk(KERN_INFO "Driver: open()\n");
 return 0;
}
static int my_close(struct inode *i, struct file *f)
{
 printk(KERN_INFO "Driver: close()\n");
 return 0;
}
//static char c;

static char text[20];// = "test\n";
static char *text_ptr = text; 
static ssize_t my_read(struct file *f, char __user *buf, size_t len, loff_t *off)
{
 int bytes_read;
 bytes_read = 0;
 //text_ptr = text;
 if (*text_ptr == 0) {
 printk(KERN_INFO "Driver: read()%u bytes\n",bytes_read);
 return 0;
 }
 while (len && *text_ptr) 
 {
 put_user(*text_ptr, buf);
 ++text_ptr;
 ++buf;
 --len;
 bytes_read++;
 }
  printk(KERN_INFO "Driver: read()%u bytes\n",bytes_read);
  printk(KERN_INFO "Data:%s\n",text);
 return bytes_read;
}
static ssize_t my_write(struct file *f, const char __user *buf, size_t len, loff_t *off)
{
 size_t i;
 
 for (i = 0; i < len && i < sizeof(text) - 1; ++i) { //prefix ++?
 get_user(text[i], buf);
 ++buf;
 }
/* text[i] = 'R';
 text[i+1] = 'e';
 text[i+2] = 'c';
 text[i+3] = 'v'; 
 text[i+1] = '\n'; */ 
 text[i+1] = 0;
text_ptr = text;
printk(KERN_INFO "Driver: write() %u bytes\n",i);
printk(KERN_INFO "Data:%s\n",text);
 return i;
}
/* if (get_user(text[i], buf)!=0)//(copy_from_user(&c, buf + len – 1, 1) != 0)
 return -EFAULT;
 else
 return len;
}*/
                          
static struct file_operations pugs_fops =
{
.owner = THIS_MODULE,
.open = my_open,
.release = my_close,
.read = my_read,
.write = my_write
};
            
static int __init mfcd_init(void) /* Constructor */
{
 printk(KERN_INFO "Gun: mfcd registered");
 if (alloc_chrdev_region(&first, 0, 3, "Andy") < 0)
       {
        return -1;
       }
 if((cl = class_create(THIS_MODULE, "chardrv"))==0)
 {
 unregister_chrdev_region(first,1);
 return -1;
 }
 if (device_create(cl, NULL, first, "%s", "mynull") == NULL)
 {
  class_destroy(cl);
  unregister_chrdev_region(first, 1);
  return -1;
 }
 cdev_init(&c_dev, &pugs_fops);
 if (cdev_add(&c_dev, first, 1) == -1)
 {
   device_destroy(cl, first);
   class_destroy(cl);
   unregister_chrdev_region(first, 1);
   return -1;
 }
 printk(KERN_INFO "<Major, Minor>: <%d, %d>\n", MAJOR(first), MINOR(first));
 return 0;
}

static void __exit mfcd_exit(void) /* Destructor */
{
 cdev_del(&c_dev);
 device_destroy(cl, first);
 class_destroy(cl);
 unregister_chrdev_region(first, 1);
 unregister_chrdev_region(first, 3);
 printk(KERN_INFO "Gun: mfcd unregistered");
}

module_init(mfcd_init);
module_exit(mfcd_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Gun ");
MODULE_DESCRIPTION("My First Character Driver");