写一段嵌入式linuxLED驱动代码

以下是一个简单的嵌入式Linux LED驱动程序的示例代码：

#include <linux/module.h>
#include <linux/init.h>
#include <linux/gpio.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>

#define DEVICE_NAME "led"
#define LED_PIN 23

static dev_t dev_num;
static struct cdev *led_cdev;
static struct class *led_class;
static struct device *led_device;

static int led_open(struct inode *inode, struct file *file)
{
    return 0;
}

static int led_release(struct inode *inode, struct file *file)
{
    return 0;
}

static ssize_t led_write(struct file *file, const char __user *buf,
                         size_t count, loff_t *ppos)
{
    int value;
    if (count != 1 || (*buf != '0' && *buf != '1'))
        return -EINVAL;
    value = (*buf == '0') ? 0 : 1;
    gpio_set_value(LED_PIN, value);
    return 1;
}

static const struct file_operations led_fops = {
    .owner = THIS_MODULE,
    .open = led_open,
    .release = led_release,
    .write = led_write,
};

static int __init led_init(void)
{
    int ret;
    ret = gpio_request_one(LED_PIN, GPIOF_OUT_INIT_LOW, "LED");
    if (ret) {
        pr_err("gpio_request_one failed\n");
        return ret;
    }
    ret = alloc_chrdev_region(&dev_num, 0, 1, DEVICE_NAME);
    if (ret) {
        pr_err("alloc_chrdev_region failed\n");
        goto err1;
    }
    led_cdev = cdev_alloc();
    if (!led_cdev) {
        pr_err("cdev_alloc failed\n");
        ret = -ENOMEM;
        goto err2;
    }
    cdev_init(led_cdev, &led_fops);
    ret = cdev_add(led_cdev, dev_num, 1);
    if (ret) {
        pr_err("cdev_add failed\n");
        goto err3;
    }
    led_class = class_create(THIS_MODULE, DEVICE_NAME);
    if (IS_ERR(led_class)) {
        pr_err("class_create failed\n");
        ret = PTR_ERR(led_class);
        goto err4;
    }
    led_device = device_create(led_class, NULL, dev_num, NULL, DEVICE_NAME);
    if (IS_ERR(led_device)) {
        pr_err("device_create failed\n");
        ret = PTR_ERR(led_device);
        goto err5;
    }
    return 0;
err5:
    class_destroy(led_class);
err4:
    cdev_del(led_cdev);
err3:
    kfree(led_cdev);
err2:
    unregister_chrdev_region(dev_num, 1);
err1:
    gpio_free(LED_PIN);
    return ret;
}

static void __exit led_exit(void)
{
    device_destroy(led_class, dev_num);
    class_destroy(led_class);
    cdev_del(led_cdev);
    unregister_chrdev_region(dev_num, 1);
    gpio_free(LED_PIN);
}

module_init(led_init);
module_exit(led_exit);

MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("LED driver");
MODULE_LICENSE("GPL");

这个驱动程序使用GPIO 23控制一个LED灯。在打开设备节点文件并写入“0”或“1”时，LED灯将相应地开启或关闭。该驱动程序使用字符设备节点，用户可以像写入文件一样控制LED灯的状态。