通过GPIO子系统编写LED驱动，应用程序控制LED灯亮灭

mycdev.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "led.h"

struct gpio_desc *gpiono_1;
struct gpio_desc *gpiono_2;
struct gpio_desc *gpiono_3;

struct device_node *dnode;

struct class *cls;
struct device *dev;
int major;

long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    int which;
    int ret = copy_from_user(&which, (void *)arg, 4);
    switch (cmd)
    {
        case LED_ON :
            switch(which)
            {
                case 1:
                    gpiod_set_value(gpiono_1, 1);
                    break;
                case 2:
                    gpiod_set_value(gpiono_2, 1); 
                    break; 
                case 3:
                    gpiod_set_value(gpiono_3, 1); 
                    break; 
                default:
                printk("输入错误\n");
            }
            break;
        
        case LED_OFF:
            switch(which)
            {
                case 1:
                    gpiod_set_value(gpiono_1, 0);
                    break;
                case 2:
                    gpiod_set_value(gpiono_2, 0); 
                    break; 
                case 3:
                    gpiod_set_value(gpiono_3, 0); 
                    break; 
                default:
                printk("输入错误\n");

            }


    }

    return 0;
}

// 定义操作方法结构体变量并赋值
struct file_operations fops = {

    .unlocked_ioctl = mycdev_ioctl,
};

static int __init mycdev_init(void)
{
    // 字符设备驱动注册
    major = register_chrdev(0, "mycdev", &fops);
    if (major < 0)
    {
        printk("字符设备驱动注册失败\n");
        return major;
    }
    printk("字符设备驱动注册成功:major=%d\n", major);

    // 向上提交目录
    cls = class_create(THIS_MODULE, "mycdev");
    if (IS_ERR(cls))
    {
        printk("向上提交目录失败\n");
        return -PTR_ERR(cls);
    }
    printk("向上提交目录成功\n");

    // 向上提交设备节点信息
    dev = device_create(cls, NULL, MKDEV(major, 0), NULL, "mycdev");
    if (IS_ERR(dev))
    {
        printk("向上提交设备节点失败\n");
        return -PTR_ERR(dev);
    }
    printk("向上提交设备节点成功\n");

    // 解析设备树节点
    dnode = of_find_node_by_name(NULL, "myleds");
    if (dnode == NULL)
    {
        printk("解析设备树数失败\n");
        return -ENOMEM;
    }
    printk("解析设备树节点成功\n");

    // 根据设备树节点解析出gpio编号并申请
    gpiono_1 = gpiod_get_from_of_node(dnode, "led1", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono_1))
    {
        printk("解析设备号1失败\n");
        return -PTR_ERR(gpiono_1);
    }
    printk("申请gpio_led1编号成功\n");

        // 根据设备树节点解析出gpio编号并申请
    gpiono_2 = gpiod_get_from_of_node(dnode, "led2", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono_2))
    {
        printk("解析设备号2失败\n");
        return -PTR_ERR(gpiono_2);
    }
    printk("申请gpio_led2编号成功\n");

        // 根据设备树节点解析出gpio编号并申请
    gpiono_3 = gpiod_get_from_of_node(dnode, "led3", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono_3))
    {
        printk("解析设备号3失败\n");
        return -PTR_ERR(gpiono_3);
    }
    printk("申请gpio_led3编号成功\n");

    // 开灯
    // gpiod_set_value(gpiono, 1);
    return 0;
}
static void __exit mycdev_exit(void)
{
    // 灭灯
    gpiod_set_value(gpiono_1, 0);
    // gpiod_set_value(gpiono_2, 0);
    // gpiod_set_value(gpiono_3, 0);

    // 释放gpio编号
    gpiod_put(gpiono_1);

     // 销毁设备节点信息
    device_destroy(cls, MKDEV(major, 0));

    // 销毁目录空间
    class_destroy(cls);

    // 注销字符设备驱动
    unregister_chrdev(major, "mycdev");
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

text.c

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "led.h"

int main(int argc, char const *argv[])
{
    int a, b;
    char buf[128] = {0};
    int fd = open("/dev/mycdev", O_RDONLY);
    if(fd < 0)
    {
        printf("打开设备文件失败%s\n", __FILE__);
        exit(-1);
    }

    while(1)
    {
        printf("请输入：1（开灯），0（关灯）>>>");
        scanf("%d", &a);
        printf("请输入控制的灯：1（LED1），2（LED2），3（LED3）>>>");
        scanf("%d", &b);
        switch(a)
        {
            case 1:
                ioctl(fd, LED_ON, &b);//开灯
                break;
            case 0:
                ioctl(fd, LED_OFF, &b);//关灯
                break;
            default:
                printf("输入错误\n");
        }
    }


    close(fd);

    return 0;
}

led,h

#ifndef __HEAD_H__
#define __HEAD_H__

//封装开关灯功能码
#define LED_ON _IOW('l', 1, int)
#define LED_OFF _IOW('1', 0, int)

#endif