linux_dev_学习笔记_字符驱动的注册和注销

2012年3月25日  Sunday

 

1、内核版本号2.6.33.20

 

2、字符设备驱动创建实例

 

3、驱动模块源文件chr_register.c

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/fcntl.h>

#define CALL_DEV_NAME "calldev"
#define CALL_DEV_MAJOR 240

int call_open(struct inode *inode ,struct file *filp)
{
    int num=MINOR(inode->i_rdev);

    printk("call open->minor : %d\n",num);

    return 0;
}

loff_t call_llseek(struct file *filp,loff_t off,int whence)
{
    printk("call llseek->off : %08X, whence : %08X\n",off,whence);
    return 0x23;
}

ssize_t call_read(struct file *filp,char *buf,size_t count,loff_t *f_pos)
{
    printk("call read->buf : %08X,count : %08X\n",buf,count);
    return 0x33;
}

ssize_t call_write(struct file *filp,const char *buf,size_t count)
{
    printk("call write->buf : %08X,count : %08X\n",buf ,count);
    return 0x43;
}

int call_ioctl(struct inode *inode,struct file *filp,
        unsigned int cmd,unsigned long arg)
{
    printk("call ioctl->cmd : %08X,arg : %08X\n",cmd,arg);
    return 0x53;
}

int call_release(struct inode *inode,struct file *filp)
{
    printk("call release\n");
    return 0;
}

struct file_operations call_fops={
    .owner = THIS_MODULE,
    .llseek = call_llseek,
    .read = call_read,
    .write = call_write,
    .ioctl = call_ioctl,
    .open = call_open,
    .release = call_release,
};

int call_init(void)
{
    int result;
    printk("call call_init\n");
    result=register_chrdev(CALL_DEV_MAJOR,CALL_DEV_NAME,&call_fops);
    if(result<0)return result;
    return 0;
}

void call_exit(void)
{
    printk("call call_exit\n");
    unregister_chrdev(CALL_DEV_MAJOR,CALL_DEV_NAME);
}

module_init(call_init);
module_exit(call_exit);

MODULE_LICENSE("Dual BSD/GPL");

4、Makefile

obj-m += chr_register.o

CURRENT_PATH := $(shell pwd)

LINUX_KERNEL := $(shell uname -r)

LINUX_KERNEL_PATH := /usr/src/linux-$(LINUX_KERNEL)

all:
    make -C $(LINUX_KERNEL_PATH) M=$(CURRENT_PATH) modules
clean:
    #make -C $(LINUX_KERNEL_PAHT) M=$(CURRENT_PATH) clean
    rm *.mod.*
    rm *.order
    rm *.o
    rm *.symvers

5、应用程序源文件call_dev.c

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>

#define DEVICE_FILENAME "/dev/calldev"

int main()
{
    int dev;
    char buff[128];
    int ret;

    printf("1) device file open\n");

    dev=open(DEVICE_FILENAME,O_RDWR |O_NDELAY);
    if(dev>=0){

        printf("2)seek function call\n");
        ret=lseek(dev,0x20,SEEK_SET);
        printf("ret=%08X\n",ret);

        printf("3)read function call\n");
        ret=read(dev,0x30,0x31);
        printf("ret=%08X\n",ret);

        printf("4)write function call\n");
        ret=write(dev,0x40,0x41);
        printf("ret=%08X\n",ret);

        printf("5)ioctl function call\n");
        ret=ioctl(dev,0x51,0x52);
        printf("ret=%08X\n",ret);

        printf("5)device file close\n");
        ret=close(dev);
        printf("ret=%08X\n",ret);

    }
    return 0;
}

6、执行方法及执行结果

~/chr_register# mknod /dev/calldev c 240 0 //创建设备文件
~/chr_register# ls /dev |grep calldev //查看设备文件是否创建成功
calldev
~/chr_register# make //编译驱动模块
~/chr_register# insmod chr_register.ko //插入驱动模块
~/chr_register# lsmod |grep chr_register //查看驱动模块是否插入成功
chr_register 1571 0
~/chr_register# ./call_app //运行app及结果
1) device file open
2)seek function call
ret=00000023
3)read function call
ret=00000033
4)write function call
ret=00000043
5)ioctl function call
ret=00000053
5)device file close
ret=00000000
~/chr_register# dmesg //驱动模块内核输出信息
[ 209.833318] call call_init
[ 245.532945] call open->minor : 0
[ 245.532999] call llseek->off : 00000020, whence : 00000000
[ 245.533320] call read->buf : 00000030,count : 00000031
[ 245.533369] call write->buf : 00000040,count : 00000041
[ 245.533440] call ioctl->cmd : 00000051,arg : 00000052
[ 245.533493] call release
[ 280.903004] call call_exit
[ 433.754550] call call_init
[ 468.565086] call open->minor : 0
[ 468.565319] call llseek->off : 00000020, whence : 00000000
[ 468.565423] call read->buf : 00000030,count : 00000031
[ 468.565473] call write->buf : 00000040,count : 00000041
[ 468.565525] call ioctl->cmd : 00000051,arg : 00000052
[ 468.565567] call release

7、移除模块及设备文件

~/chr_register# rm /dev/calldev //删除设备文件
~/chr_register# rmmod chr_register.ko //移除驱动模块