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//     ---        ， struct     
 //        ，         ，            
 struct led_desc{
        dev_t  devno;
    struct cdev *cdev;
    struct class *cls;
    struct device *dev;
 };
//    
struct  led_desc  *led_dev;

static  int __init key_drv_init(void)
{
    int ret;
    //    
    //       
    //  GFP_KERNEL           ，       
    key_dev = kzalloc(sizeof(struct s5pv210_key), GFP_KERNEL);
    if(key_dev == NULL)
    {
        printk(KERN_ERR "kzalloc error
");
        return -ENOMEM;
    }
    // 1,       
    key_dev->dev_major = register_chrdev(0, "s5pv210_key_drv", &key_fops);
    if(key_dev->dev_major < 0)
    {
        printk(KERN_ERR "kzalloc error
");
        ret = -ENODEV;
        goto err_0;
    }

    
    // 2,       
    //  /sys/class/key_cls    
    key_dev->cls = class_create(THIS_MODULE, "key_cls");
    if(IS_ERR(key_dev->cls))
    {
        printk(KERN_ERR "class_create error
");
        ret = PTR_ERR(key_dev->cls);
        goto err_1;
    }

    // （    ） /sys/class/key_cls/key/
    //  /dev/key1
    key_dev->dev = device_create(key_dev->cls, NULL, MKDEV(key_dev->dev_major,1),NULL, "key1");
    if(IS_ERR(key_dev->dev))
    {
        printk(KERN_ERR "device_create error
");
        ret = PTR_ERR(key_dev->dev);
        goto err_2;
    }


    // 4,       


err_2:
    class_destroy(key_dev->cls);

err_1:
    unregister_chrdev(key_dev->dev_major, "s5pv210_key_drv");
    
err_0:
    kfree(key_dev);
    return ret;

}

static  int __init led_drv_init(void)
{
    int ret;
    //    
    //       
    //  GFP_KERNEL           ，       
    led_dev = kzalloc(sizeof(struct led_desc), GFP_KERNEL);
    if(led_dev == NULL)
    {
        printk(KERN_ERR "kzalloc error
");
        return -ENOMEM;
    }
    // 1,       
    //      register_chrdev_region(dev_t from,unsigned count,const char * name)
    //    
    ret = alloc_chrdev_region(&led_dev->devno, 0, 1, "led_drv"); //  /proc/devices
    if(ret != 0)
    {
        printk(KERN_ERR "alloc_chrdev_region error
");
        goto err_0;
    }
    printk("major number is %d
", MAJOR(led_dev->devno));
    
    //    cdev
    led_dev->cdev = cdev_alloc();
    cdev_init(led_dev->cdev, &led_fops);
    cdev_add(led_dev->cdev, led_dev->devno, 1);

    // 2,       
    //  /sys/class/led_cls    
    led_dev->cls = class_create(THIS_MODULE, "led_cls");
    if(IS_ERR(led_dev->cls))
    {
        printk(KERN_ERR "class_create error
");
        ret = PTR_ERR(led_dev->cls);
        goto err_1;
    }

    //  /sys/class/led_cls/led0/
    //  /dev/led0
    led_dev->dev = device_create(led_dev->cls, NULL, led_dev->devno,NULL, "led%d", 0);
    if(IS_ERR(led_dev->dev))
    {
        printk(KERN_ERR "device_create error
");
        ret = PTR_ERR(led_dev->dev);
        goto err_2;
    }


    // 4,       



err_2:
    class_destroy(led_dev->cls);

err_1:
    cdev_del(led_dev->cdev);
    unregister_chrdev_region(led_dev->devno,1);
    
err_0:
    kfree(led_dev);
    return ret;

}

static void __exit  led_drv_exit(void)
{
    //    
    iounmap(gpc0conf);
    device_destroy(led_dev->cls,led_dev->devno);
    class_destroy(led_dev->cls);
    cdev_del(led_dev->cdev);
    unregister_chrdev_region(led_dev->devno,1);
    kfree(led_dev);
}