如何在Dragonboard 410c上实现一个秒表定时器

}

/*模块卸载函数*/
void second_exit(void)
{
  cdev_del(&second_devp->cdev);   /*注销cdev*/
  kfree(second_devp);     /*释放设备结构体内存*/
  unregister_chrdev_region(MKDEV(second_major, 0), 1); /*释放设备号*/
}
MODULE_AUTHOR("Sola");
MODULE_LICENSE("Dual BSD/GPL");
module_param(second_major, int, S_IRUGO);
module_init(second_init);
module_exit(second_exit);

（2）驱动程序文件timer_demo_test.c的具体实现代码如下：
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/time.h>
main()
{
  int fd;
  int counter = 0;
 int old_counter = 0;
  /*打开/dev/second设备文件*/
  fd = open("/dev/second", O_RDONLY);
  if (fd !=  - 1)
  {
   while (1)
    {
      read(fd,&counter, sizeof(unsigned int));//读目前经历的秒数
      if(counter!=old_counter)
      { 
      printf("seconds after open /dev/second :%d\n",counter);
      old_counter = counter;
      } 
    }    
  }
  else
  {
  printf("Device open failure\n");
  }
}