ARM&Linux 下驱动开发第二节

驱动文件：qudong.c,make生成qudong.ko文件，烧录到ARM板上

#include<linux/init.h>

#include<linux/module.h>

#include<linux/kernel.h>

#include <linux/poll.h>    /* COPY_TO_USER */

#include<linux/errno.h>

#define DEV_NAME "rwtest"



static int major=0;

static int MAX_BUF_LEN=1024;

static char drv_buf[1024];

static int WRI_LENGTH=0;

/************************************写入*************************************************/

static ssize_t  dx_write(struct file *file, const char __user *buffer, size_t count, loff_t * ppos)

{ 

    if(count > MAX_BUF_LEN)count = MAX_BUF_LEN;

    copy_from_user(drv_buf , buffer, count);

    WRI_LENGTH = count;

    printk("write data to driver\n");

    return count;

}

/**************************************读取***********************************************/

static ssize_t  dx_read(struct file *filp, char __user *buffer, size_t count, loff_t *ppos)

{

    int i=0,j=0;

    if(count > MAX_BUF_LEN)

        count=MAX_BUF_LEN;

    for(i=strlen(drv_buf);i>0;i--)

    {

        buffer[j]=drv_buf[i-1];

        j++;

    }

    //copy_to_user(buffer,drv_buf,count);

    printk("read data from driver\n");

    return count;

}

 //===========================打开=========================================

static int dx_open(struct inode *inode, struct file *filp)

{

    printk("device open sucess!\n");

    return 0;

}

/**********************************release***************************************************/

static int  dx_release(struct inode *inode, struct file *filp)

{

    printk("device release\n");

    return 0;

}



//======================结构体,驱动各属性==================================================

static struct file_operations file_opt = {

    owner:    THIS_MODULE,

    write:    dx_write,    

    read:    dx_read,    

    open:    dx_open,

    release:dx_release,

};

//----------------------------------------------------------------------

static int __init qudong_init(void)

{

    int ret;

     ret = register_chrdev(0, DEV_NAME, &file_opt);

     if(ret<0)

     {

         printk(DEV_NAME " can't get major number\n");

        return 0;

     }

     major=ret;

     printk("dx module major number is %d\n", ret);

     return 0;

}

//-----------------------------------------------------------------------

static void __exit qudong_exit(void)

{

     unregister_chrdev(major,DEV_NAME);

     printk("exit\n");

}

module_init(qudong_init);

module_exit(qudong_exit);

MODULE_LICENSE("GPL");

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Makefile文件：

## Makefile template.



 

obj-m := qudong.o

UNAME := $(shell uname -r)

PWD := $(shell pwd)

ADVMOD := qudong

 

defualt:

    @make -C /lib/modules/$(UNAME)/build SUBDIRS=$(PWD) modules

 

clean:    

    @rm -f *.o    

    @rm -f *.ko

    @rm -f *.mod.c

    @rm -f .*.cmd

    @rm -rf .tmp_versions

#endif

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或者ARM下的Makefile文件：

ifneq ($(KERNELRELEASE),)

obj-m := hello.o

else

KDIR := /usr/src/linux2.6.28

all:

    make -C $(KDIR) M=$(PWD) modules ARCH=arm CROSS_COMPILE=arm-linux-

clean:

    rm -f *.ko *.o *.mod.o *.mod.c *.symvers  modul*

endif

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测试程序如下：

#include <stdio.h>

#include <stdlib.h>

#include <fcntl.h>

#include <unistd.h>

#include <sys/ioctl.h>

#include<string.h>

int main()

{

    int fd=0;

    int ret=0;

    char bufw[100]={'\0'};

    char bufr[100]={'\0'};

    fd=open("/dev/rwtest",O_RDWR);

    if(fd<0)

    {

        perror("open error\n");

        return 0;

    }

    printf("Please input string:\n");

    scanf("%s",bufw);

    ret=write(fd,bufw,strlen(bufw));

    if(ret<0)

    {

        perror("write error\n");

        return 0;

    }

    printf("burw====%s\n",bufw);

    ret=read(fd,bufr,99);

    if(ret<0)

    {

        perror("read error\n");

        return 0;

    }

    printf("bufr====%s\n",bufr);

    close(fd);

    return 0;

}

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