設備樹：

leds:leds{
  compatible = "xx,xx-led";
 };

驅動：

static unsigned int led = 0;

static ssize_t led_status_show(struct device *dev, struct device_attribute *attr, char *buf)
{
 return sprintf(buf, "%s:%d.n", "led", led);
}

static ssize_t led_status_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
 sscanf(buf, "%d", &led);

 return count;
}

static DEVICE_ATTR(led_status, 0600, led_status_show, led_status_store);

static struct attribute *led_attributes[]={
 &dev_attr_led_status.attr,
 NULL,
};


static const struct attribute_group led_attrs={
 .attrs = led_attributes,
};

static int xx_led_probe(struct platform_device *pdev)
{
 sysfs_create_group(&pdev- >dev.kobj, &led_attrs);
 return 0;
}

static int xx_led_remove(struct platform_device *pdev)
{
 sysfs_remove_group(&pdev- >dev.kobj, &led_attrs);
 return 0;
}

static const struct of_device_id xx_led_of_match[] = {
 {.compatible = "xx,xx-led"},
};


static struct platform_driver xx_led_driver = {
 .probe = xx_led_probe,
 .remove = xx_led_remove,
 .driver = {
  .name = "xx-led",
  .owner = THIS_MODULE,
  .of_match_table = xx_led_of_match,
 },
};

static int __init xx_led_init(void)
{
 return platform_driver_register(&xx_led_driver );
}

static void __exit xx_led_exit(void)
{
 platform_driver_unregister(&xx_led_driver);
}

module_init(xx_led_init);
module_exit(xx_led_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("xx led driver");
MODULE_AUTHOR("Vincent");
MODULE_VERSION("V1.0.00");

驅動加載后，就可以在linux終端中，使用cat和echo命令來查看和修改驅動中led變量的值。例如：

//查看led變量的值
cat /sys/devices/platform/leds/led_status
led:0.

//修改led變量的值為9
echo 9 > /sys/devices/platform/leds/led_status
//查看
cat /sys/devices/platform/leds/led_status
led:9.