一个完整的linux 驱动demo 加应用测试 demo

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测试环境,开发环境

feadora 11

kernal 2.6.29.4

驱动代码

driverdemo.c

#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/cdev.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#define simple_MAJOR 200
static unsigned char simple_inc=0;
static char demoBuffer[256];
int simple_open(struct inode *inode,struct file *filp){
if(simple_inc>0) return -ERESTARTSYS;
simple_inc++;
return 0;
}
int simple_release(struct inode *inode,struct file *filp){
simple_inc--;
return 0;
}
ssize_t simple_read(struct file *filp,char __user *buf,size_t count,loff_t *f_pos){
if(copy_to_user(buf,demoBuffer,count)){
count=-EFAULT;
}
return count;
}

size_t simple_write(struct file *file,const char __user *buf,size_t count,loff_t *f_pos){
if (copy_from_user(demoBuffer + *f_pos,buf,count)){
count = -EFAULT;
}
return count;
}

void simple_cleanup_module(void){
unregister_chrdev(simple_MAJOR,"simple");
printk("simple_cleanup_module!\n");

}

static const struct file_operations simple_fops={
.owner=THIS_MODULE,
.open=simple_open,
.release=simple_release,
.read=simple_read,
.write=simple_write,
};

int simple_init_module(void){
int ret;
ret=register_chrdev(simple_MAJOR,"simple",&simple_fops);
if(ret<0){
printk("Unable to register character device %d!/n",simple_MAJOR);
return ret;
}
return 0;
}

module_init(simple_init_module);
module_exit(simple_cleanup_module);

MODULE_LICENSE("Dual BSD/GPL");

Makefile 文件

ifeq ($(KERNELRELEASE),)
KERNELDIR ?=/usr/src/linux-2.6.29.4
INCLUDE ?=./
PWD :=$(shell pwd)
modules:
$(MAKE) -C $(KERNELDIR) -I $(INCLUDE) M=$(PWD) modules
modules_install:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install
clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions
else
obj-m :=driverdemo.o
endif

生成安装驱动

make //会生成driverdemo.ko文件
insmod driverdemo.ko //安装到系统内 需要在root 下运行

创建设备文件

mknod /dev/fgj c 200 0

这里我们只要关心200是什么， 200为设备号，也需要在root 下运行

我们在前面代码里

#define simple_MAJOR 200

这就是设备号

应用程序code

test.c

#include <stdio.h>
#include <fcntl.h>
int main(void){
int fd;
int i;
char data[256];
int retval;
fd=open("/dev/fgj",O_RDWR);
if(fd==-1){
perror("error open\n");
exit(-1);
}
printf("open /dev/fgj successfully\n");
//writing data
retval=write(fd,"http://blog.csdn.net/ssihc0",26);
if(retval==-1){
perror("write error \n");
exit(-1);
}

retval=read(fd,data,26);
if(retval==-1){
perror("read error\n");
exit(-1);
}
data[retval]=0;
printf("read successfully:%s\n",data);
close(fd);
return 0;

}

生成

gcc test.c

运行./a.out

open /dev/fgj successfully

read successfully:http://blog.csdn.net/ssihc0

下面是一些我们在驱动开发过程经常要用到的COMMAND

history
cat /var/log/messages | tail  //看一下我们的调试消息

mknod /dev/fgj c 200 0    //建设备文件

cat /proc/modules | grep d* //查看我们的驱动MODULE

insmod driverdemo.ko   //安装 设备
rmmod 1-2module.ko   //删除设备

ismod //查看设备信息

dmesg  | tail  //看一下我们的调试消息

insmod test.ko a=3 b=2 AddOrSub=2 //带参数加载驱动