#include <linux/module.h>
            #include <linux/types.h>
            #include <linux/fs.h>
            #include <linux/errno.h>
            #include <linux/mm.h>
            #include <linux/sched.h>
            #include <linux/init.h>
            #include <linux/cdev.h>
            #include <asm/io.h>
            #include <asm/system.h>
            #include <asm/uaccess.h>
            #include <linux/timer.h>
            #include <asm/atomic.h>
            #define SECOND_MAJOR 0
            static int second_major = SECOND_MAJOR;
            struct second_dev
            {
            struct cdev cdev;
            atomic_t counter;
            struct timer_list s_timer;
            };
            struct second_dev *second_devp;
            static void second_timer_handle(unsigned long arg)
            {
            mod_timer(&second_devp->s_timer, jiffies + HZ);
            atomic_inc(&second_devp->counter);
            printk(KERN_ERR "current jiffies is %ld\n",jiffies);
            }
            int second_open(struct inode *inode, struct file *filp)
            {
            init_timer(&second_devp->s_timer);
            second_devp->s_timer.function = &second_timer_handle;
            second_devp->s_timer.expires = jiffies + HZ;
            add_timer(&second_devp->s_timer);
            atomic_set(&second_devp->counter, 0);
            return 0;
            }
            int second_release(struct inode *inode, struct file *filp)
            {
            del_timer(&second_devp->s_timer);
            return 0;
            }
            static ssize_t second_read(struct file *filp, char __user *buf, size_t count,
            loff_t *ppos)
            {
            int counter;
            counter = atomic_read(&second_devp->counter);
            if (put_user(counter, (int *)buf))
            {
            return -EFAULT;
            }else
            {
            return sizeof(unsigned int);
            }
            }
            static const struct file_operations second_fops =
            {
            .owner = THIS_MODULE,
            .open = second_open,
            .release = second_release,
            .read = second_read,
            };
            static void second_setup_cdev(struct second_dev *dev, int index)
            {
            int err, devno = MKDEV(second_major, index);
            cdev_init(&dev->cdev, &second_fops);
            dev->cdev.owner = THIS_MODULE;
            dev->cdev.ops = &second_fops;
            err = cdev_add(&dev->cdev, devno, 1);
            if (err)
            {
            printk(KERN_NOTICE "Error %d add second%d", err, index);
            }
            }
            int second_init(void)
            {
            int ret;
            dev_t devno = MKDEV(second_major, 0);
            if (second_major)
            {
            ret = register_chrdev_region(devno, 1, "second");
            }else
            {
            ret = alloc_chrdev_region(&devno, 0, 1, "second");
            second_major = MAJOR(devno);
            }
            if (ret < 0)
            {
            return ret;
            }
            second_devp = kmalloc(sizeof(struct second_dev), GFP_KERNEL);
            if (!second_devp)
            {
            ret = -ENOMEM;
            goto fail_malloc;
            }
            memset(second_devp, 0, sizeof(struct second_dev));
            second_setup_cdev(second_devp, 0);
            return 0;
            fail_malloc:
            unregister_chrdev_region(devno, 1);
            }
            void second_exit(void)
            {
            cdev_del(&second_devp->cdev);
            kfree(second_devp);
            unregister_chrdev_region(MKDEV(second_major, 0), 1);
            }
            MODULE_AUTHOR("Song Baohua");
            MODULE_LICENSE("Dual BSD/GPL");
            module_param(second_major, int, S_IRUGO);
            module_init(second_init);
            module_exit(second_exit);
            附上用戶端的測試程序：
            #include <stdio.h>
            #include <unistd.h>
            #include <fcntl.h>
            int main(void)
            {
            int fd, i;
            int data;
            fd = open("/dev/second",O_RDONLY);
            if (fd < 0)
            {
            printf("open /dev/second error\n");
            }
            for(i = 0; i < 20; i++)
            {
            read(fd, &data, sizeof(data));
            printf("read /dev/second is %d\n",data);
            sleep(1);
            }
            close(fd);
            }