#include <linux/module.h>
#include <linux/init.h>
#include <linux/of.h>

struct device_node *nd; /* 设备节点 */
struct property *comppro;

static int __init helloworld_init(void) {
    pr_info("Hello world initialization!\n");

    // 第一个参数设置为 NULL，从根节点开始查找
    nd = of_find_node_by_path("/my_backlight");
    if (nd == NULL) {
        printk("my_backlight node not found!\n");
        return -EINVAL;
    } else {
        printk("my_backlight node found!\n");
    }

    comppro = of_find_property(nd, "compatible", NULL);
    if(comppro == NULL){
        ret = -EINVAL;
        goto fail_finish;
    }else{
        printk("compatible=%s\r\n",(char *)comppro->value);
    }

goto fail_finish:
    return ret;
}

static void __exit helloworld_exit(void) {
    pr_info("Hello world exit\n");
}

module_init(helloworld_init);
module_exit(helloworld_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("John Madieu <john.madieu@gmail.com>");
MODULE_DESCRIPTION("Linux kernel module skeleton");