字符设备驱动函数

        ret = alloc_chrdev_region(&led_dev.dev, 0, 1, "led");
	cdev_init(&led_dev.dev_c, &led_ops);
	cdev_add(&led_dev.dev_c, led_dev.dev, 1);
	led_dev.cdev_class = class_create(THIS_MODULE, "led");
	device_create(led_dev.cdev_class, NULL, led_dev.dev, 0, "led");

    unregister_chrdev_region(led_dev.dev, 1);
    device_destroy(led_dev.cdev_class, led_dev.dev); 
    class_destroy(led_dev.cdev_class);
    cdev_del(&led_dev.dev_c);

初始化-释放

1. alloc_chrdev_region --- unregister_chrdev_region

2. cdev_init, cdev_add, --- cdev_del (这个是不是这样的我不知道。 cdev_alloc与之对应？)

3. class_create               --- class_destroy

4. device_create            --- device_destroy  (必须在class_destroy 释放之前调用)