#define GPIO_OFT(x) ((x) - 0x56000000)
#define GPFCON (*(volatile unsigned long *)(gpio_va + GPIO_OFT(0x56000050)))

static int s3c24xx_leds_open(struct inode *inode, struct file *file)

{

    int minor = MINOR(inode->i_rdev); //MINOR(inode->i_cdev);

    switch(minor)

    {

        case : /* /dev/leds */

        {

            // 配置3引脚为输出

            GPFCON &= ~(0x3<<(*));
//oo00:这里GPFCON是虚拟地址，在驱动模块开始（见下面s3c24xx_leds_init）的时候，这个虚拟地址已经通过宏定义 #define GPFCON (*(volatile unsigned long *)(gpio_va + GPIO_OFT(0x56000050)))被映射到物理地址

            GPFCON |= (<<(*));

    .......

}

static struct file_operations s3c24xx_leds_fops = {

    .owner  =   THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */

    .open   =   s3c24xx_leds_open,

    .read    =    s3c24xx_leds_read,

    .write    =    s3c24xx_leds_write,

};

static int __init s3c24xx_leds_init(void)//模块入口

{

    gpio_va = ioremap(0x56000000, 0x100000); // 物理地址0x56000000， 映射区分配的大小0x100000字节

    printk(DEVICE_NAME "gpio_va = %x\n",gpio_va);//oo00 debug

    register_chrdev(LED_MAJOR, DEVICE_NAME, &s3c24xx_leds_fops);

    ...

    leds_class = class_create(THIS_MODULE, "leds");

    ...

    for (minor = ; minor < ; minor++)

    {

        leds_class_devs[minor] = class_device_create(leds_class, NULL, MKDEV(LED_MAJOR, minor), NULL, "led%d", minor);

        ..

    }

}