1.在用户空间中有个字符数组，要求在内核空间打印，用dmesg查看。（ioctl实现）
zy.h，封装一个发送用的命令码
#ifndef __LED_H__
#define __LED_H__
#define UACCESS_BUF _IOW('a',1,char [128])
#endifzy.c 申请并自动创建设备结点，在mydev_ioctl函数中确认命令码并接受字符数组信息存储在kbuf中，同时打印kbuf信息。
#include <linux/module.h>
#include <linux/init.h>
#include<linux/device.h>
#include<linux/uaccess.h>
#include<linux/io.h>
#include<linux/fs.h>
#include"zy.h"
#define CNAME "zy"
int major;
struct class* cls;
struct device* dev;
char kbuf[128]={};
int mydev_open (struct inode *inode, struct file *file)
{
return 0;
}
int mydev_close (struct inode *inode, struct file *file)
{
return 0;
}
long mydev_ioctl (struct file *file, unsigned int cmd,unsigned long arg)
{
int ret;
if(cmd==UACCESS_BUF)
{
ret=copy_from_user(kbuf,(void*)arg,sizeof(kbuf));
if(ret)
{
printk("copy from user error\n");
return EIO;
}
printk("kbuf = %s\n",kbuf);
}
return 0;
}
const struct file_operations fops={
.open=mydev_open,
.release=mydev_close,
.unlocked_ioctl=mydev_ioctl,
};
static int __init demo_init(void)
{
major=register_chrdev(0,CNAME,&fops);
if(major<0)
{
printk("register_chrdev error\n");
return major;
}
printk("major=%d\n",major);
cls=class_create(THIS_MODULE,CNAME);
if(IS_ERR(cls))
{
return PTR_ERR(cls);
}
//提交设备结点信息
dev=device_create(cls,NULL,MKDEV(major,0),NULL,CNAME);
if(IS_ERR(dev))
{
return PTR_ERR(dev);
}
return 0;
}
static void __exit demo_exit(void)
{
device_destroy(cls,MKDEV(major,0));
class_destroy(cls);
unregister_chrdev(major,CNAME);
}
module_init(demo_init);
module_exit(demo_exit);
MODULE_LICENSE("GPL");test.c 打开驱动文件并发送字符数组
#include<stdio.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<unistd.h>
#include<stdlib.h>
#include<string.h>
#include<sys/ioctl.h>
#include "zy.h"
int main(int argc, char const *argv[])
{
char buf[128]={"You have an ambitious nature and may make a name for yourself"};
int fd=-1;
fd=open("/dev/zy",O_RDWR);
if(-1==fd)
{
perror("open error");
return -1;
}
ioctl(fd,UACCESS_BUF,buf);
return 0;
}makefile：编译工具
ARCH?=x86
NAME?=zy
ifeq ($(ARCH),x86)
KERNEDIR:=/lib/modules/$(shell uname -r)/build
else
KERNEDIR:=/home/ubuntu/linux-5.10.61
endif
PWD:=$(shell pwd)
all:
make -C $(KERNEDIR) M=$(PWD) modules
clean:
make -C $(KERNEDIR) M=$(PWD) clean
obj-m:=$(NAME).o实验结果截图
二：将结构题传递到内核空间，在内核空间打印，把值+10后传递会用户空间打印。
zy2.h：封装结构体和发送接收两个命令码。
#ifndef __LED_H__
#define __LED_H__
typedef struct {
int width;
int high;
}image_t;
#define struct_send _IOW('a',1,image_t)
#define struct_recv _IOR('a',1,image_t)
#endifzy2.c：在接收后打印，然后加10返回用户空间
#include <linux/module.h>
#include <linux/init.h>
#include<linux/device.h>
#include<linux/uaccess.h>
#include<linux/io.h>
#include<linux/fs.h>
#include"zy2.h"
#define CNAME "zy2"
int major;
struct class* cls;
struct device* dev;
image_t kimage;
int mydev_open (struct inode *inode, struct file *file)
{
return 0;
}
int mydev_close (struct inode *inode, struct file *file)
{
return 0;
}
long mydev_ioctl (struct file *file, unsigned int cmd,unsigned long arg)
{
int ret;
if(cmd==struct_send)
{
ret=copy_from_user(&kimage,(void*)arg,sizeof(image_t));
if(ret)
{
printk("copy from user error\n");
return EIO;
}
printk("width=%d\nhigh=%d\n",kimage.width,kimage.high);
kimage.width+=10;
kimage.high+=10;
}
else if(cmd==struct_recv)
{
ret=copy_to_user((void*)arg,&kimage,sizeof(image_t));
if(ret)
{
printk("copy to user error\n");
return EIO;
}
}
return 0;
}
const struct file_operations fops={
.open=mydev_open,
.release=mydev_close,
.unlocked_ioctl=mydev_ioctl,
};
static int __init demo_init(void)
{
major=register_chrdev(0,CNAME,&fops);
if(major<0)
{
printk("register_chrdev error\n");
return major;
}
printk("major=%d\n",major);
cls=class_create(THIS_MODULE,CNAME);
if(IS_ERR(cls))
{
return PTR_ERR(cls);
}
//提交设备结点信息
dev=device_create(cls,NULL,MKDEV(major,0),NULL,CNAME);
if(IS_ERR(dev))
{
return PTR_ERR(dev);
}
return 0;
}
static void __exit demo_exit(void)
{
device_destroy(cls,MKDEV(major,0));
class_destroy(cls);
unregister_chrdev(major,CNAME);
}
module_init(demo_init);
module_exit(demo_exit);
MODULE_LICENSE("GPL");test2.c：发送接收并打印
#include<stdio.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include<unistd.h>
#include<stdlib.h>
#include<string.h>
#include<sys/ioctl.h>
#include "zy2.h"
int main(int argc, char const *argv[])
{
image_t image={20,40};
int fd=-1;
fd=open("/dev/zy2",O_RDWR);
if(-1==fd)
{
perror("open error");
return -1;
}
ioctl(fd,struct_send,&image);
ioctl(fd,struct_recv,&image);
printf("width=%d\nhigh=%d\n",image.width,image.high);
close(fd);
return 0;
}makefile：编译工具
ARCH?=x86
NAME?=zy2
ifeq ($(ARCH),x86)
KERNEDIR:=/lib/modules/$(shell uname -r)/build
else
KERNEDIR:=/home/ubuntu/linux-5.10.61
endif
PWD:=$(shell pwd)
all:
make -C $(KERNEDIR) M=$(PWD) modules
clean:
make -C $(KERNEDIR) M=$(PWD) clean
obj-m:=$(NAME).o结果截图
