字符设备驱动实例：自动挂载SD卡

guitarhua 2012-11-09

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字符设备驱动实例：自动挂载SD卡

时间:2010-10-28 09:26来源: 作者: 点击:129次

内核驱动文件: l200_mac.c #include l200.h extern char l200_sddev_name[10]; //define and export in drivers/usb/storage/usb.c extern int sd_insert_status; //define and export in drivers/scsi/w90p710_sdio.c extern int macPlugStatus; //define an

内核驱动文件: l200_mac.c
#include "l200.h"

extern char l200_sddev_name[10]; //define and export in drivers/usb/storage/usb.c
extern int sd_insert_status;    //define and export in drivers/scsi/w90p710_sdio.c
extern int macPlugStatus;       //define and export in drivers/net/w90p710_mac.c

static int mac_open(struct inode *inode, struct file *file)
{
     return 0;
}

static int mac_release(struct inode *inode, struct file *file)
{
     return 0;
}

static int mac_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
        int status = 0;
        char buffer[10];
    switch(cmd)
    {
        case GET_ETH_STATUS:     // cmd=1, whether network wire is plugin or not
              return    macPlugStatus;

         case GET_SD_STATUS:     // cmd=2, check whether SD card insert or not
                     if(copy_from_user(buffer, (const char*)arg, sizeof(buffer)) != 0)
                         return -EFAULT;
                     printk("Receive argument: %s\n", buffer);

                     status = sd_insert_status;
                     if(1 == sd_insert_status)
                     {
                         if(copy_to_user((unsigned char*)arg, &l200_sddev_name, 10) != 0)
                             return -EFAULT;
                         printk("SD Card insert with device name %s1\n", l200_sddev_name);
                     }
                     return status;

        default:
            return -1;
    }
    return 0;
}

static struct file_operations mac_fops=
{
    .ioctl = mac_ioctl,
    .open = mac_open,
    .release = mac_release,
};

static void mac_module_exit(void)
{
    unregister_chrdev(MAC_MAJOR, MAC_NAME);
}

static int __init mac_module_init(void)
{

    if((register_chrdev(MAC_MAJOR, MAC_NAME, &mac_fops)) < 0)
    {
        mac_module_exit();
        printk("Regist L200 MAC device failure...\n");
        return -ENODEV;
    }
    printk("Regist L200 MAC device success...\n");

    return 0;
}

module_init(mac_module_init);
module_exit(mac_module_exit);

主动挂载SD卡措施：
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/wait.h>
#include <signal.h>
#include <sys/ioctl.h>
#include <fcntl.h>

#define GET_SD_STATUS       2

int daemon_init(void)
{
        pid_t pid, cpid;
        int status;

        setsid(); /* become session leader */

        chdir("/"); /* change working directory */

        umask(0); /* clear file mode creation mask */

        close(0); /* close stdin */
        close(1); /* close stdout */
        close(2); /* close stderr */

        switch(pid = vfork())   //parent sleeps, child_proc_1 comes
        {
                case 0:
                        waitpid(pid, &status, WUNTRACED);
                        //vfork succ , child_proc_1 sleeps, child_proc_2 comes
                        if(cpid = vfork())
                        {
                                waitpid(cpid, &status, WUNTRACED);
                                _exit(0);
                        }

                        /* child_proc_2 continues */
                        return 1;

                case -1:
                        return(-1);//vfork err

                default:
                        exit(0); /* parent only, exit */
        }

        return(0);
}

int main(void)
{
        int     fd = -1;
        int     ret = -1;
        int     sd_mnt_flag = 0;
        char    sd_name[10];
        char    mnt_cmd[40];

        if( -1 == daemon_init() )
        {
                printf("can't fork self\n");
                exit(0);
        }

        if(-1 == (fd=open("/dev/eth", O_RDWR, 755)))
        {
                perror("open sd device failure\n");
                return 0;
        }

        while(1)
        {
                sleep(3);//sleep 3 seconds

                if(-1 == (ret=ioctl(fd, GET_SD_STATUS, sd_name )) )
                {
                        perror("ioctl on sd failure.\n");
                        return 0;
                }

                if( 1==ret && 1!=sd_mnt_flag) //SD card insert, and not mount
                {
                   snprintf(mnt_cmd, sizeof(mnt_cmd), "mount -t vfat /dev/%s1 /media/sdc", sd_name);
                   system(mnt_cmd);
                   sd_mnt_flag = 1;
                }
                else if ( 0==ret && 0!=sd_mnt_flag)   // SD card pull out and not umount
                {
                    system("umount /media/sdc");
                    sd_mnt_flag = 0;
                }
        }

        close(fd);
        return 0;
}