char_driv_simp.c

简单的字符设备驱动程序

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/fs.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include<linux/kdev_t.h>
#include<linux/cdev.h>
 unsigned long size ;
 static char *Kong_buf="Hello moto hahah";
 struct cdev *dev;

static char *char_name="Kong_simp_driver";
//static int major=221;
//static int minor=0;
 dev_t dev_no=MKDEV(223, 0);
static int Kong_open(struct inode *inode,struct file *filp)
 {//struct Kong_str *dev;
  //dev=container_of(inode->i_cdev,struct Kong_str,cdev);
  //filp->private_data=dev;
    Kong_buf=kzalloc(1024,GFP_KERNEL);
return 0;
}
static int Kong_release(struct inode *inode, struct file *filp)
 {  // cdev_del(dev);
//unregister_chrdev_region(dev_no,1);
//kfree(Kong_buf);
return 0;
}
static ssize_t Kong_read(struct file *filp,char __user *buf,size_t count, loff_t *f_pos)
{ ssize_t retval=88; 
   //char *Kong_buf[1024];
//memset(Kong_buf,0,1024);
// dev=filp->private_data;
   //// if(*f_pos>=dev->size)
//goto out;
  //if(*f_pos+count>dev->size)
  // count=dev->size-*f_pos;

     retval=copy_to_user(buf,Kong_buf,count);
retval=count;
     //*f_pos+=count;
//retval=count;
//out:
return retval;
}
static ssize_t Kong_write(struct file *filp,char __user *buf,size_t count,loff_t *f_pos)
{
  ssize_t retval;
//memset(Kong_buf,0,1024);
 //ssize_t retval=0;
//dev=filp->private_data;
   // dev->Kong_buf=kmalloc(count+10,GFP_KERNEL);
//if (!dev->Kong_buf)
 // goto out;

 retval=copy_from_user(Kong_buf,buf,count);
retval=count;
//*f_pos+=count;
//retval=count;
//out:
return retval;
}	

static struct file_operations Kong_fops={
  .owner=	THIS_MODULE,
  .read=	Kong_read,
 .write=	Kong_write,
  .open=	Kong_open,
.release=	Kong_release,};
 static int __init Kong_init(void){
  int result;
result=register_chrdev_region(dev_no,1,char_name);
if(result) printk("Register no success!");
dev=cdev_alloc();
dev->owner=THIS_MODULE;
dev->ops=&Kong_fops;
cdev_init(dev,&Kong_fops);
cdev_add(dev,dev_no,1);
printk("Mount Kong_driver Successful!\n");
return 0;
 }   
static void __exit Kong_exit(void){
     cdev_del(dev);
   kfree(Kong_buf);
unregister_chrdev_region(dev_no,1);
  

printk("Umount Kong_driver Successful!\n");
}

module_init(Kong_init);
module_exit(Kong_exit);