分别编写一个应用程序和字符驱动程序实现wiringPi的digitalWrite(pin, value)功能 ，代码内带有注释

应用程序代码：

#include <stdio.h>
#include <wiringPi.h>

int main()
{
    // 初始化wiringPi库
    wiringPiSetup();

    // 设置GPIO17为输出模式
    pinMode(0, OUTPUT);

    // 设置GPIO17输出高电平
    digitalWrite(0, HIGH);

    return 0;
}

字符驱动程序代码：

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

#define GPIO_PIN 17      // GPIO17对应的引脚号
#define DEVICE_NAME "wiringPi"   // 设备名称

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A simple example Linux module.");
MODULE_VERSION("0.01");

static int majorNumber;   // 设备号
static char message[256] = {0};  // 存储从用户空间读入的数据
static short sizeOfMessage;      // message的长度
static int openCounter = 0;      // 记录设备被打开的次数
static struct class* wiringPiClass = NULL;   // 设备类指针
static struct device* wiringPiDevice = NULL; // 设备指针

// 在设备被打开时执行的函数
static int wiringPi_open(struct inode* inodep, struct file* filep)
{
    openCounter++;
    printk(KERN_INFO "wiringPi: Device has been opened %d time(s)\n", openCounter);
    return 0;
}

// 在设备被关闭时执行的函数
static int wiringPi_release(struct inode* inodep, struct file* filep)
{
    printk(KERN_INFO "wiringPi: Device successfully closed\n");
    return 0;
}

// 在从设备中读取数据时执行的函数
static ssize_t wiringPi_read(struct file* filep, char* buffer, size_t len, loff_t* offset)
{
    int errorCount = 0;
    errorCount = copy_to_user(buffer, message, sizeOfMessage);

    if (errorCount == 0)
    {
        printk(KERN_INFO "wiringPi: Sent %d characters to the user\n", sizeOfMessage);
        return (sizeOfMessage = 0);
    }
    else
    {
        printk(KERN_INFO "wiringPi: Failed to send %d characters to the user\n", errorCount);
        return -EFAULT;
    }
}

// 在向设备中写入数据时执行的函数
static ssize_t wiringPi_write(struct file* filep, const char* buffer, size_t len, loff_t* offset)
{
    int errorCount = 0;
    errorCount = copy_from_user(message, buffer, len);

    if (errorCount == 0)
    {
        sizeOfMessage = len;
        printk(KERN_INFO "wiringPi: Received %d characters from the user\n", len);

        // 设置GPIO17的输出值
        if (message[0] == '1')
        {
            gpio_set_value(GPIO_PIN, 1);
        }
        else if (message[0] == '0')
        {
            gpio_set_value(GPIO_PIN, 0);
        }
        else
        {
            printk(KERN_ALERT "wiringPi: Invalid value received from user\n");
            return -EINVAL;
        }

        return len;
    }
    else
    {
        printk(KERN_ALERT "wiringPi: Failed to receive %d characters from the user\n", errorCount);
        return -EFAULT;
    }
}

// 设备文件操作集
static struct file_operations fops =
{
    .open = wiringPi_open,
    .read = wiringPi_read,
    .write = wiringPi_write,
    .release = wiringPi_release,
};

// 模块初始化函数
static int __init wiringPi_init(void)
{
    int error = 0;

    // 初始化GPIO
    if (!gpio_is_valid(GPIO_PIN))
    {
        printk(KERN_ALERT "wiringPi: Invalid GPIO pin\n");
        return -ENODEV;
    }
    gpio_request(GPIO_PIN, "wiringPi");
    gpio_direction_output(GPIO_PIN, 0);

    // 分配设备号
    majorNumber = register_chrdev(0, DEVICE_NAME, &fops);

    if (majorNumber < 0)
    {
        printk(KERN_ALERT "wiringPi: Failed to register a major number\n");
        return majorNumber;
    }

    // 创建设备类
    wiringPiClass = class_create(THIS_MODULE, DEVICE_NAME);

    if (IS_ERR(wiringPiClass))
    {
        unregister_chrdev(majorNumber, DEVICE_NAME);
        printk(KERN_ALERT "wiringPi: Failed to create a device class\n");
        return PTR_ERR(wiringPiClass);
    }

    // 创建设备文件
    wiringPiDevice = device_create(wiringPiClass, NULL, MKDEV(majorNumber, 0), NULL, DEVICE_NAME);

    if (IS_ERR(wiringPiDevice))
    {
        class_destroy(wiringPiClass);
        unregister_chrdev(majorNumber, DEVICE_NAME);
        printk(KERN_ALERT "wiringPi: Failed to create a device file\n");
        return PTR_ERR(wiringPiDevice);
    }

    printk(KERN_INFO "wiringPi: Device driver successfully registered\n");
    return 0;
}

// 模块退出函数
static void __exit wiringPi_exit(void)
{
    gpio_set_value(GPIO_PIN, 0);
    gpio_free(GPIO_PIN);
    device_destroy(wiringPiClass, MKDEV(majorNumber, 0));
    class_unregister(wiringPiClass);
    class_destroy(wiringPiClass);
    unregister_chrdev(majorNumber, DEVICE_NAME);
    printk(KERN_INFO "wiringPi: Device driver successfully unregistered\n");
}

// 注册初始化和退出函数
module_init(wiringPi_init);
module_exit(wiringPi_exit);

注意：以上代码中的GPIO_PIN变量定义为17，如果你使用的是其他引脚，需要修改该变量的值。另外，由于Raspberry Pi上的GPIO引脚编号和wiringPi库中的编号不同，因此需要在代码中将wiringPi库的编号转换为GPIO引脚编号。例如，将wiringPi库中的0号引脚转换为GPIO17，需要将GPIO_PIN变量定义为17。