void release_region ( unsigned long start， unsigned long len);

#include <linux/fs。h。>
#include <linux/ioport。h。>
 
struct file_operations fops;
unsigned long start， len;
 
int init_module (void)
{
 int status;
 start = 0xff90;
 len   = 0x90;
 
 register_chrdev(254，"your_device"，&fops);
 
 status = check_region (start， len);
 if (status == 0) {
     printk ("The ports are available in that range。
");
     request_region(start，len，"your_device");
 } else {
     printk ("The ports are already in use。 Try other range。
");
     return (status);
 }
 return 0;
}
 
void cleanup_module (void)
{
 release_region(start， len);
 printk (" ports are freed successfully
");
 unregister_chrdev(254，"your_device");}
 printk (" your device is unregistered
");
}

$cat /proc/ioports