hello.c

刚学LINUX驱动模块时写的一个测试程序

#include <linux/module.h>
#include <linux/config.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <asm/uaccess.h>

#define MAJOR_NUM 125
#define DEVICE_NAME "char_dev"
#define BUF_LEN 10

#define IOCTL_SET_MSG _IOR(MAJOR_NUM, 0, int*)
#define IOCTL_GET_MSG _IOR(MAJOR_NUM, 1, int*)

static Device_Open=0;
static char *Message_Ptr;
static char Message[BUF_LEN];
static int flags=0xff;

static int device_open(struct inode *inode, struct file *file)
{
  printk("Device Open\n");

  if (Device_Open) return -EBUSY;

  Device_Open++;
  
  //MOD_INC_USE_COUNT;

  Message_Ptr = Message;

  return 0;
}


static int device_release(struct inode *inode, struct file *file)
{
  printk("Device release\n");
  Device_Open--;
 
  return 0;
}


static ssize_t device_write(struct file *file,const char *buffer,size_t length,loff_t *offset)
{
  int value;
  int bytes_writes=10;
  int *data=(int*)buffer;
   char str[256];
   
   get_user(value,data);
   flags=value;
   sprintf(str,"device write %d\n",flags);
   printk((str));

  return bytes_writes;
}


static ssize_t device_read(struct file *file,char *buffer,size_t length,loff_t *offset)
{
  int bytes_read=10;
  int *data=(int *)buffer;
  char str[256];

  sprintf(str,"device_read %d\n",flags);
  printk((str));
  
  put_user(flags,data);
  return bytes_read;
}

int device_ioctl(struct inode *inode,
                 struct file *file,
                 unsigned int ioctl_num,/* The number of the ioctl */
                 unsigned long ioctl_param) /* The parameter to it */
{
  int	temp;
  int *data;
  int   ioctl;
  char  str[256];

  printk(("Device_ioctl\n"));
  
  switch (ioctl_num) 
  {
    case IOCTL_SET_MSG:
     
      data = (int*) ioctl_param;
      
      get_user(temp, data);
      sprintf(str, "Device_ioctl SET_MSG %d\n", temp);
      printk((str));
      
      break;

    case IOCTL_GET_MSG:
    
      printk(("Device_ioctl PUT_MSG\n"));

      break;
  }

  return 0;
};

static struct file_operations Fops={
.owner=THIS_MODULE,
.read=device_read,
.write=device_write,
.open=device_open,
.release=device_release,
.ioctl=device_ioctl,
};

static int test_init(void){

   int ret_val;	
   ret_val=register_chrdev(MAJOR_NUM,DEVICE_NAME,&Fops);
     if(ret_val<0){
       printk("<0>register failure with %d\n","num",ret_val);
       return ret_val;
      }

 printk ("<0>%s The major device number is %d.\n",
          "Registeration is a success",MAJOR_NUM);
 printk("<0>Module ok! \n");
 return 0;
}

static void test_clear(void){
int ret;
 printk("<0>Goodbye!\n");
ret=unregister_chrdev(MAJOR_NUM,DEVICE_NAME);
if(ret<0)
printk("Error unregister:%d\n",ret);
}

MODULE_LICENSE("GPL-huming");

module_init(test_init);
module_exit(test_clear);