1. #include <linux/init.h>
2. #include <linux/module.h>
3. #include <linux/fs.h>
4. #include <linux/uaccess.h>
5. #include <init.h>
6. #include <slab.h>
7. #include <cdev.h>
8.  
9. #define MYDEV_NAME "mycdrv"
10. #define KBUF_SIZE (size_t) (10*PAGE_SIZE)
11.  
12. static char *kbuf;
13. static dev_t first;
14. static unsigned int count = 1;
15. static int my_major = 700, my_minor = 0;
16. static struct cdev *my_cdev;
17.  
18. static int mycdrv_open (struct inode *inode, struct file *file)
19. {
20.   printk(KERN_INFO "OPENING device: %s\n\n", MYDEV_NAME);
21.   return 0;
22. }
23.  
24. static int mycdrv_release (struct inode *inode, struct file *file)
25. {
26.   printk(KERN_INFO "CLOSING device: %s\n\n", MYDEV_NAME);
27.   return 0;
28. }
29.  
30. static ssize_t;
31. mycdrv_read (struct file *file, char __user * buf, size_t lbuf, loff_t * ppos)
32. {
33.   int nbytes = lbuf - copy_to_user(buf, kbuf + *ppos, lbuf);
34.   *ppos += nbytes;
35.   prink(KERN_INFO "\n READING function, nbytes=%d, pos %d\n", nbytes, (int)*ppos);
36.   return nbytes;
37. }
38. static ssize_t;
39. mycdrv_write(struct file *file, char __user * buf, size_t lbuf, loff_t * ppos)
40. {
41.   int nbytes = lbuf - copy_from_user(buf, kbuf + *ppos, lbuf);
42.   *ppos += nbytes;
43.   prink(KERN_INFO "\n WRITING function, nbytes=%d, pos %d\n", nbytes, (int)*ppos);
44.   return nbytes;
45. }
46.  
47. static const struct file_operations mycdrv_fops = {
48.   .owner = THIS_MODULE,
49.   .read = mycdrv_read,
50.   .write = mycdrv_write,
51.   .open = mycdrv_open,
52.   .release = mycdrv_release,
53. };
54.  
55. static int __init my_init (void)
56. {
57.   kbuf = kmalloc(KBUF_SIZE, GFP_KERNEL);
58.   first = MKDEV(my_major, my_minor);
59.   register_chrdev_region(first, count, MYDEV_NAME);
60.   my_cdev = cdev_alloc();
61.   cdev_init(my_cdev, &mycdrv_fops);
62.   cdev_add(my_cdev, first, count);
63.   printk(KERN_INFO "\nSucceeded in registering character device %s\n", MYDEV_NAME);
64.   return 0;
65. }
66.  
67. static void __exit my_exit (void)
68. {
69.   cdev_del(my_cdev);
70.   unregister_chrdev_region(first, count);
71.   printk(KERN_INFO "\ndevice unregistered\n");
72.   kfree(kbuf);
73. }
74.  
75.  
76. module_init(my_init);
77. module_exit(my_exit);
78.