Android系统移植与驱动开发概述(2)

if (copy_from_user(mem, buf, tmp))
    {
        return -EFAULT;
    }
    else
    {
        for (i = 0; i < 4; i++)
        {
            tmp = ioread32(S3C64XX_GPMDAT);
            if (mem[i] == '1')
            {
                tmp &= (~(1 << i));
            }
            else
            {
                tmp |= (1 << i);
            }

iowrite32(tmp, S3C64XX_GPMDAT);

}
        return count;
    }

}

static struct file_operations dev_fops =
{ .owner = THIS_MODULE, .unlocked_ioctl = s3c6410_leds_ioctl, .write =
        s3c6410_leds_write };
static struct cdev leds_cdev;

//创建设备文件（/dev/s3c6410_leds）
static int leds_create_device(void)
{
    int ret = 0;
    int err = 0;

//  初始化cdev的成员，并建立cdev和file_operations之间的连接
    cdev_init(&leds_cdev, &dev_fops);
    leds_cdev.owner = THIS_MODULE;
    if (major > 0)
    {
        //  获取设备号（主设备号和次设备号）
        dev_number = MKDEV(major, minor);
        err = register_chrdev_region(dev_number, DEVICE_COUNT, DEVICE_NAME);
        if (err < 0)
        {
            printk(KERN_WARNING "register_chrdev_region() failed\n");
            return err;
        }
    }
    else
    {
        err = alloc_chrdev_region(&leds_cdev.dev, 10, DEVICE_COUNT,
                DEVICE_NAME);
        if (err < 0)
        {
            printk(KERN_WARNING "alloc_chrdev_region() failed\n");
            return err;
        }

major = MAJOR(leds_cdev.dev);
        minor = MINOR(leds_cdev.dev);
        //dev_number = MKDEV(major, minor);
        dev_number = leds_cdev.dev;

}
    ret = cdev_add(&leds_cdev, dev_number, DEVICE_COUNT);
    leds_class = class_create(THIS_MODULE, DEVICE_NAME);
    device_create(leds_class, NULL, dev_number, NULL, DEVICE_NAME);

return ret;
}

static void leds_init_gpm(int leds_default)
{
    int tmp = 0;
    //  初始化端口配置寄存器
    tmp = ioread32(S3C64XX_GPMCON);
    tmp &= (~0xFFFF);
    tmp |= 0x1111; // 0001000100010001
    iowrite32(tmp, S3C64XX_GPMCON);

//  初始化端口上拉电路寄存器
    tmp = ioread32(S3C64XX_GPMPUD);
    tmp &= (~0xFF);
    tmp |= 0xAA; // 01010101
    iowrite32(tmp, S3C64XX_GPMPUD);

//  初始化端口数据寄存器
    tmp = ioread32(S3C64XX_GPMDAT);
    tmp &= (~0xF);
    tmp |= leds_default;
    iowrite32(tmp, S3C64XX_GPMDAT);
}

//  初始化LED驱动
static int leds_init(void)
{
    int ret;
    ret = leds_create_device();
    leds_init_gpm(~leds_state);
    printk(DEVICE_NAME"\tinitialized\n");

printk("param0\t%s\n", params[0]);
    printk("param1\t%s\n", params[1]);
    printk("param2\t%s\n", params[2]);

return ret;
}
static void leds_destroy_device(void)
{
    device_destroy(leds_class, dev_number);

if (leds_class)
        class_destroy(leds_class);
    unregister_chrdev_region(dev_number, DEVICE_COUNT);

return;

}
static void leds_exit(void)
{
    leds_destroy_device();
    printk(DEVICE_NAME"\texit!\n");
}

module_init(leds_init);
module_exit(leds_exit);
module_param(leds_state, int, S_IRUGO|S_IWUSR);
module_param_array(params, charp, &param_size, S_IRUGO|S_IWUSR);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Lining");

总结一下学习Linux 驱动要做些什么：