如何在sys/kernel下创建一个扫描灯的kobject节点

#include<linux/init.h>

#include<linux/module.h>

#include<linux/kobject.h>

#include<linux/sysfs.h>

#include<linux/string.h>

extern int scan_type;

static ssize_t scan_type_show(struct kobject *kobj, struct kobj_attribute *attr,  //6.具体的读取函数
                       char *buf)

{

         return sprintf(buf, "%d\n", scan_type);

}

/* Sysfs attributes cannot be world-writable. */  //5.属性对应的操作函数，可以向这几个属性节点读取或写入数据

static struct kobj_attribute scantype_attribute =

        __ATTR(scanner_type, 0664, scan_type_show, NULL);

static struct attribute *attrs[] = {    //4.一组属性

        &scantype_attribute.attr,
        NULL,    
};

static struct attribute_group attr_group = {
        .attrs = attrs,
};

static struct kobject *scanner_led_kobj;

static int __init scanner_led_init(void)

{

        int retval;

        scanner_led_kobj = kobject_create_and_add("kobject_scanner_led", kernel_kobj);//2.在/sys/kernel下建立一个kobject_scanner_led的目录项

        if (!scanner_led_kobj)

                return -ENOMEM;

        retval = sysfs_create_group(scanner_led_kobj, &attr_group);//3.建立一个属性文件函数组

        if (retval)

                kobject_put(scanner_led_kobj);

        return retval;

}

static void __exit scanner_led_exit(void)

{

        kobject_put(scanner_led_kobj);

}

module_init(scanner_led_init);//1.程序入口

module_exit(scanner_led_exit);