upperdrv.c

请在解压时看说明文档 内有详细说明

/*****upperdrv.c *****/
/**************************************************************/
#ifndef __KERNEL__
#    define __KERNEL__
#endif
#ifndef MODULE
#    define MODULE
#endif


#define WE_REALLY_WANT_TO_USE_A_BROKEN_INTERFACE
#define __NO_VERSION__
#include <linux/version.h>
#include <linux/module.h>

char kernel_version[]=UTS_RELEASE;

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/string.h>
#include <linux/slab.h>

#include <asm/io.h>
#include <asm/segment.h>
#include <asm/uaccess.h>

#ifndef _UPPER_DEVICE_H
#define _UPPER_DEVICE_H
#include <linux/ioctl.h>
#define UPPER_MAJOR 117
#define UPPER_LOW2UPPER 1 // change the input string from low to upper characters
#define UPPER_UNCHAN 0     //copy the input string to the output
#define UPPER_MAGIC UPPER_MAJOR
#define UPPER_RESET _IO(UPPER_MAGIC,0)   // reset the data
#define UPPER_QUERY_NEW_MSG _IO(UPPER_MAGIC,1) // check for new message
#define UPPER_QUERY_MSG_LENGTH _IO(UPPER_MAGIC,2) // get message length
#define IOC_NEW_MSG 1
#endif

#define DEVICE_NAME "upper"

#include "softdev.h"

const int upperdrv_major=117;
static int usage,new_msg;       // control flags
unsigned char *data;
unsigned char **data_point;


// open the device
      static int upper_open(struct inode *inode,struct file *filp) {
	    MOD_INC_USE_COUNT;
	    printk("This upper drive is in open!\n");
	    return 0;
	}

// close the device
	static int upper_release(struct inode *inode,struct file *filp) {
		MOD_DEC_USE_COUNT;
		printk("This upper drive is in release!\n");
		return 0;
	}

// write to device －transfer from user space to softdev
    static ssize_t upper_write(struct file *filp,const char *buf,
size_t count,loff_t *offset) {
		int length; 
		if(count<0)
			return -EINVAL;
		if(usage || new_msg)
			return -EBUSY;
	    	usage=1;
   		kfree(data);
		data=kmalloc(sizeof(char)*(count+1),GFP_KERNEL);
		copy_from_user(data,buf,count);   // start transfering
		length=softdev_send(data,count);
		if(length==-1) 
			printk("string no longer than 1512!\n");
		else if(length==-2)
			printk("device is busy!\n");
		usage=0;
		new_msg=1;
		return count;
	}	


// read from device －transfer from softdev to user space
	static ssize_t upper_read(struct file *filp,char *buf,size_t count,
loff_t *offset) {
		int length;
		kfree(data_point);
		data_point=(unsigned char **)kmalloc(sizeof(unsigned char*),GFP_KERNEL);
		if(count<0)
			return -EINVAL;
		if(usage)
			return -EBUSY;
		usage=1;	
		length=softdev_recv(data_point);
		if(length<count)
			count=length;
		copy_to_user(buf,*data_point,count);    // start transfering
		new_msg=0;
		usage=0;
		return count;
	}


// ioctl for device －control or set the device
	static int upper_ioctl(struct inode *inode,struct file *filp,
unsigned long int cmd,unsigned long arg) {
		int ret=0;
		switch(cmd) {
		case UPPER_LOW2UPPER:		
		               softdev_ioctl(1);
				 printk("[in upper]now change upper finished");
				 return 2;
		               break;
		case UPPER_UNCHAN:
		               softdev_ioctl(0);
				printk("[in upper]now stop change upper finished");
				return 3;
		               break;
		case UPPER_RESET:
				kfree(data);
				kfree(data_point);
				data=NULL;
				data_point=NULL;
				new_msg=0;
				break;
		case UPPER_QUERY_NEW_MSG:
			if(new_msg)
				return IOC_NEW_MSG;
			break;
		case UPPER_QUERY_MSG_LENGTH:
			if(data==NULL) {
				return 0;
			}
			else {
				return strlen(data);
			}
			break;
		default:
			return -ENOTTY;
		}
		return ret;
	}


	struct file_operations upper_fops={
		owner:	THIS_MODULE,
		NULL,                 // seek
		read:	upper_read,         // read
		write:	upper_write,        // write
		NULL,                 // readdir
		NULL,                 // poll
		ioctl:	upper_ioctl,        // ioctl
		NULL,                 // mmap
		open:	upper_open,         // open
		NULL,                 // flush
		release:	upper_release,      // release
		NULL,                 // fsync
		NULL,                 // fasync
		NULL,			// check media change
		NULL,                 // revalidate
		NULL,                  // lock
		NULL,
		NULL,
	};

// Initialize the module －Register the character device
	int init_module(){
		if(register_chrdev(UPPER_MAJOR,DEVICE_NAME,&upper_fops)!=0) {
			printk("registering character device major: %d failed!\n",UPPER_MAJOR);
			return -EIO;
		}
		else
			{
			printk("registering char device UPPER success!\n");
			}
		// initialize the data ptr
		data=NULL;
		data_point=NULL;
		new_msg=0;
		return 0;
	}

// Clean up －Unregister the character device
	void cleanup_module() {
		// free data memory if any
		if(data)
			kfree(data);
		if(data_point)
			kfree(data_point);
		unregister_chrdev(UPPER_MAJOR,DEVICE_NAME);
		printk("Sorry! The UPPER is unloading now!\n");
	}