dirver.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>

static int major = 0;
module_param(major, int, 0);
static int nb_dev = 1;
module_param(nb_dev, int, 0);

static struct cdev mydriver_dev;

/*                                                                                                                                                                                                    
 * Operation                                                                                                                                                                                          
 */
static int mydriver_open(struct inode *inode, struct file *filp) {
  printk("file opened\n");
  return 0;
}

static ssize_t mydriver_read(struct file *filp, char *buf, size_t count, loff_t *f_pos) {
  printk("file read\n");
  return 0;
}

static ssize_t mydriver_write(struct file *filp, const char *buf, size_t count, loff_t *f_pos) {
  printk("file written\n");
  return 0;
}

static int mydriver_release(struct inode *inode, struct file *file) {
  printk("file released\n");
  return 0;
}

struct file_operations mydriver_fops = {
  .owner = THIS_MODULE,
  .read = mydriver_read,
  .write = mydriver_write,
  .open = mydriver_open,
  .release = mydriver_release
};

/*
 * Module Initialisation                                                                                                                                                                              
 */

static void setup_cdev(struct cdev *m_dev, int minor, struct file_operations *m_fops)
{
  int err, dev = MKDEV(major, minor);

  cdev_init(m_dev, m_fops);
  m_dev->owner = THIS_MODULE;
  m_dev->ops = m_fops;
  err = cdev_add(m_dev, dev, 1);
  if (err)
    printk(KERN_NOTICE "Error adding cdev: %d\n", err);
}

static int allocate_dev_number(void) {
  int dev, result;

  if (major) {
    dev = MKDEV(major, 0);
    result = register_chrdev_region(dev, nb_dev, "mydriver");
  } else {
    result = alloc_chrdev_region(&dev, 0, nb_dev, "mydriver");
    major = MAJOR(dev);
  }
  if (result < 0) {
    printk(KERN_WARNING "mydriver: can't get major %d\n", major);
  }
  return result;
}

static int __init mydriver_init(void)
{
  allocate_dev_number();
  setup_cdev(&mydriver_dev, 0, &mydriver_fops);
  printk("mydriver: init with major=%d nb_dev=%d\n", major, nb_dev);
  return 0;
}

static void __exit mydriver_exit(void)
{
  int dev = MKDEV(major, 0);

  cdev_del(&mydriver_dev);
  return;
}

module_init(mydriver_init);
module_exit(mydriver_exit);

MODULE_LICENSE("GPL");