8253.c

编写了对微机8253芯片的驱动程序

/* joy_wudan  2007/12/12 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <asm/io.h> 
/*functions*/
int init_module(void);
void cleanup_module(void);
static int device_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg);
static int device_release(struct inode *inode, struct file *file);
static int device_open(struct inode *inode, struct file *file);
static struct file_operations fops = {
	  ioctl :       device_ioctl,
	  open:         device_open,
	  release:      device_release,
      
};
static int device_open(struct inode *inode, struct file *file)
{
	  return 0;
}
static int device_release(struct inode *inode, struct file *file)
{
	  Device_Open --;     /* We're now ready for our next caller */
	   return 0;
}
static int device_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
    switch(cmd)
    {
        case SET_MODE:
            outb(0xb6,0x43);
            break;
        case SET_FREQ:
            int count,count_low,count_high,clock=1190000;//PC机的时钟频率，它可以是一个全局变量；
            count=clock/arg;//count为对应频率下应计数次数；
            count_low=count & 0xFF;
            count_high=count>>8;
            outb(count_low,0x42);
            outb(count_high,0x42);
            break;
       case START_BEEP:
            outb(0x03,0x61);
            break;
        case STOP_BEEP:
            outb(0x00,0x61);
            break;
        case READ_KEY:
            (unsigned char*)arg=inb(0x60);
            break;    
        case DELAY:
            mdalay(arg);
            break;
        default:
            break;
    }
                     
}
int init_module(void)
{
       register_chrdev(Major, DEVICE_NAME, &fops);
 	   return 0;
}
void cleanup_module(void)
{
       unregister_chrdev(Major, DEVICE_NAME);
      
}