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/* Necessary includes for drivers */

#include <linux/init.h>

#include <linux/config.h>

#include <linux/module.h>

#include <linux/kernel.h> /* printk() */

#include <linux/slab.h> /* kmalloc() */

#include <linux/fs.h> /* everything... */

#include <linux/errno.h> /* error codes */

#include <linux/types.h> /* size_t */

#include <linux/proc_fs.h>

#include <linux/fcntl.h> /* O_ACCMODE */

#include <linux/ioport.h>

#include <asm/system.h> /* cli(), *_flags */

#include <asm/uaccess.h> /* copy_from/to_user */

#include <asm/io.h> /* inb, outb */

MODULE_LICENSE("Dual BSD/GPL");

/* Function declaration of parlelport.c */

int parlelport_open(struct inode *inode, struct file *filp);

int parlelport_release(struct inode *inode, struct file *filp);

ssize_t parlelport_read(struct file *filp, char *buf,

                       size_t count, loff_t *f_pos);

ssize_t parlelport_write(struct file *filp, char *buf,

                       size_t count, loff_t *f_pos);

void parlelport_exit(void);

int parlelport_init(void);

/* Structure that declares the common */

/* file access fcuntions */

struct file_operations parlelport_fops = {

  read: parlelport_read,

  write: parlelport_write,

  open: parlelport_open,

  release: parlelport_release

};

/* Driver global variables */

/* Major number */

int parlelport_major = 61;

/* Control variable for memory */

/* reservation of the parallel port*/

int port;

module_init(parlelport_init);

module_exit(parlelport_exit);

int parlelport_init(void) {

  int result;

  /* Registering device */

  result = register_chrdev(parlelport_major, "parlelport",

      &parlelport_fops);

  if (result < 0) {

    printk(

      "<1>parlelport: cannot obtain major number %d\n",

      parlelport_major);

    return result;

  }

  <parlelport modified init module>

  printk("<1>Inserting parlelport module\n");

  return 0;

  fail:

    parlelport_exit();

    return result;

}

void parlelport_exit(void) {

  /* Make major number free! */

  unregister_chrdev(parlelport_major, "parlelport");

  <parlelport modified exit module>

  printk("<1>Removing parlelport module\n");

}

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

  /* Success */

  return 0;

}

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

  /* Success */

  return 0;

}

ssize_t parlelport_read(struct file *filp, char *buf,

  size_t count, loff_t *f_pos) {

  /* Buffer to read the device */

  char parlelport_buffer;

  <parlelport inport>

  /* We transfer data to user space */

  copy_to_user(buf,&parlelport_buffer,1);

  /* We change the reading position as best suits */

  if (*f_pos == 0) {

    *f_pos+=1;

    return 1;

  } else {

    return 0;

  }

}

ssize_t parlelport_write( struct file *filp, char *buf,

  size_t count, loff_t *f_pos) {

  char *tmp;

  /* Buffer writing to the device */

  char parlelport_buffer;

  tmp=buf+count-1;

  copy_from_user(&parlelport_buffer,tmp,1);

  <parlelport outport>

  return 1;

}