linux内核空间和用户空间数据拷贝驱动代码和测试程序代码

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一、驱动代码

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/wait.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/slab.h>

#define BUFFER_MAX    (64)
#define OK            (0)
#define ERROR         (-1)

struct cdev *gDev;
struct file_operations *gFile;
dev_t  devNum;
unsigned int subDevNum = 1;
int reg_major  =  232;    
int reg_minor =   0;
char buffer[BUFFER_MAX];

int hello_open(struct inode *p, struct file *f)
{
    printk(KERN_INFO "hello_open\n");
    return 0;
}

ssize_t hello_write(struct file *f, const char __user *u, size_t s, loff_t *l)
{
	printk(KERN_INFO "hello_write\n");
    /*
	int writelen = 0;
    writelen = BUFFER_MAX>s ? s : BUFFER_MAX;
    if (copy_from_user(buffer, u, writelen)) {
		return -EFAULT;
	}
	*/
	return 0;
}
ssize_t hello_read(struct file *f, char __user *u, size_t s, loff_t *l)
{
	printk(KERN_INFO "hello_read\n");
    int readlen;
    readlen = BUFFER_MAX>s ? s : BUFFER_MAX;
    if (copy_to_user(u, buffer, readlen)) {
    	return -EFAULT;
	}
    return readlen;
}
int hello_init(void)
{
    devNum = MKDEV(reg_major, reg_minor);
    if(OK == register_chrdev_region(devNum, subDevNum, "helloworld")){
        printk(KERN_INFO "register_chrdev_region ok \n"); 
    }else {
    	printk(KERN_INFO "register_chrdev_region error n");
        return ERROR;
    }
    printk(KERN_INFO " hello driver init \n");
    gDev = kmalloc(sizeof(struct cdev), GFP_KERNEL);
    gFile = kmalloc(sizeof(struct file_operations), GFP_KERNEL);
    gFile->open = hello_open;
    gFile->read = hello_read;
    gFile->write = hello_write;
    gFile->owner = THIS_MODULE;
    cdev_init(gDev, gFile);
    cdev_add(gDev, devNum, 1);
    return 0;
}

void __exit hello_exit(void)
{
 	printk(KERN_INFO " hello driver exit \n");
    cdev_del(gDev);
    kfree(gFile);
    kfree(gDev);
    unregister_chrdev_region(devNum, subDevNum);
    return;
}
module_init(hello_init);
module_exit(hello_exit);
MODULE_LICENSE("GPL");

二、驱动Makefile

ifneq ($(KERNELRELEASE),)
obj-m := helloDev.o
else
PWD := $(shell pwd)
#KDIR:=/home/jinxin/linux-4.9.229
#KDIR:= /lib/modules/4.4.0-31-generic/build
KDIR := /lib/modules/`uname -r`/build
all:
	make -C $(KDIR) M=$(PWD)
clean:	
	rm -rf *.o *.ko *.mod.c *.symvers *.c~ *~
endif

三、测试程序write

#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/select.h>
#include <unistd.h>

#define DATA_NUM    (32)
int main(int argc, char *argv[])
{
    int fd, i;
    int r_len, w_len;
    fd_set fdset;
    char buf[DATA_NUM] = "hello world";
    fd = open("/dev/hello", O_RDWR);
    if(-1 == fd) {
      	perror("open file error\n");
		return -1;
    }	
	else {
		printf("open success\n");
	}
    w_len = write(fd, buf, DATA_NUM);
    if(w_len == -1) {
		perror("write error\n");
		return -1;
	}
    printf("write len: %d\n", w_len);
	close(fd);
    return 0;
}

四、测试程序read

#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/select.h>


#define DATA_NUM    (32)
int main(int argc, char *argv[])
{
    int fd, i;
    int r_len, w_len;
    fd_set fdset;
    char rbuf[DATA_NUM];
    memset(rbuf,0,DATA_NUM);
    fd = open("/dev/hello", O_RDWR);
    if(-1 == fd) {
      	perror("open file error\n");
		return -1;
    }	
	else {
		printf("open successe\n");
	}
    
	r_len = read(fd, rbuf, DATA_NUM);
	if(r_len == -1) {
		perror("read error\n");
		return -1;
	}
    printf("read len: %d\n", r_len);
    printf("%s\n", rbuf);
	close(fd);
    return 0;
}

关注”技术简说“（13站同名），带你由浅入深学习linux内核源码。linux内核开发100讲免费教程，每天晚上9点准时更新，敬请收看。进我主页点”视频“栏目即可观看。