驱动开发-GPIO子系统实现LED123在应用端控制

头文件

#ifndef __HEAD_H__
#define __HEAD_H__ 

//构建LED开关的功能码，添加ioctl第三个参数
#define LED_ON _IOW('l',1,int)
#define LED_OFF _IOW('l',0,int)

#endif 

驱动程序代码

mychrdev.c

#include 
#include 
#include
#include
#include
#include
#include
#include 
#include "head.h"

struct cdev *cdev;
char kbuf[128]={0};
unsigned int major=0;
unsigned int minor=0;
dev_t devno;
module_param(major,uint,0664);//方便在命令行传递major的值
struct class*cls;
struct device *dev;

struct device_node *dnode;
struct gpio_desc *gpiono[3];

int mycdev_open(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}

long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    int which;
    //获取arg对应的用户空间中到的值
    int ret = copy_from_user(&which,(void *)arg,4);
    if(ret){
        printk("从用户空间数据失败\n");
        return -EIO;
    }
    switch (cmd) {
        case LED_ON:
            switch (which) {
                case 1:                            // LED1
                    gpiod_set_value(gpiono[0], 1); // LED1开灯
                    break;
                case 2:                            // LED2
                    gpiod_set_value(gpiono[1], 1); // LED2开灯
                    break;
                case 3:                            // LED3
                    gpiod_set_value(gpiono[2], 1); // LED3开灯
                    break;
            }
            break;
    case LED_OFF:
        switch (which) {
                case 1:                            // LED1
                    gpiod_set_value(gpiono[0], 0); // LED1开灯
                    break;
                case 2:                            // LED2
                    gpiod_set_value(gpiono[1], 0); // LED2开灯
                    break;
                case 3:                            // LED3
                    gpiod_set_value(gpiono[2], 0); // LED3开灯
                    break;
            }
            break;
        break;
    }

    return 0;
}

int mycdev_close(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}

// 定义操作方法结构体变量并赋值
struct file_operations fops = {
    .open = mycdev_open,
    .unlocked_ioctl = mycdev_ioctl,
    .release = mycdev_close,
};

static int __init mycdev_init(void)
{
    /*
    // 字符设备驱动注册
    major = register_chrdev(0, "mychrdev", &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,"myled");
    if(IS_ERR(cls)){
        printk("向上提交目录失败\n");
        return -PTR_ERR(cls);
    }
    printk("向上提交目录信息成功\n");
    // 向上提交设备节点信息
    devs = device_create(cls, NULL, MKDEV(major,0), NULL, "myled");
    if(IS_ERR(devs)){
        printk("向上提交设备节点信息失败\n");
        return -PTR_ERR(devs);
    }
    printk("向上提交设备节点成功\n");
    */

    //MARK 设备驱动相关
    int ret;
    //为字符设备驱动对象申请空间
    cdev=cdev_alloc();
    if(cdev==NULL)
    {
        printk("字符设备驱动对象申请空间失败\n");
        ret=-EFAULT;
        goto out1;
    }
    printk("申请对象空间成功\n");
    
    //初始化字符设备驱动对象
    cdev_init(cdev,&fops);

    //申请设备号
    if(major>0)//静态指定设备号
    {
        ret=register_chrdev_region(MKDEV(major,minor),3,"myled");
        if(ret)
        {
            printk("静态申请设备号失败\n");
            goto out2;
        }
    }
    else if(major==0)//动态申请设备号
    {
        ret=alloc_chrdev_region(&devno,minor,3,"myled");
        if(ret)
        {
            printk("动态申请设备号失败\n");
            goto out2;
        }
        major=MAJOR(devno);//获取主设备号
        minor=MINOR(devno);//获取次设备号

    }
    printk("申请设备号成功\n");

    //注册字符设备驱动对象
    ret=cdev_add(cdev,MKDEV(major,minor),3);
    if(ret)
    {
        printk("注册字符设备驱动对象失败\n");
        goto out3;
    }
    printk("注册字符设备驱动对象成功\n");

    //向上提交目录信息
    cls=class_create(THIS_MODULE,"myled");
    if(IS_ERR(cls))
    {
        printk("向上提交目录失败\n");
        ret=-PTR_ERR(cls);
        goto out4;
    }
    printk("向上提交目录成功\n");

    //向上提交设备节点信息
    int i;
    for(i=0;i<3;i++)
    {
        dev=device_create(cls,NULL,MKDEV(major,i),NULL,"myled%d",i);
        if(IS_ERR(dev))
        {
            printk("向上提交设备节点信息失败\n");
            ret=-PTR_ERR(dev);
            goto out5;
        }
    }
    printk("向上提交设备信息成功\n");

    //MARK 设备树相关
    // 解析LED的设备树节点
    dnode = of_find_node_by_path("/myled");
    if (dnode == NULL)
    {
        printk("解析设备树节点失败\n");
        return -ENXIO;
    }
    printk("解析GPIO信息成功\n");
    // 申请gpio对象
    gpiono[0] = gpiod_get_from_of_node(dnode, "led1-gpio", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono))
    {
        printk("申请gpio对象失败\n");
        return -ENXIO;
    }
    gpiono[1] = gpiod_get_from_of_node(dnode, "led2-gpio", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono))
    {
        printk("申请gpio对象失败\n");
        return -ENXIO;
    }
    gpiono[2] = gpiod_get_from_of_node(dnode, "led3-gpio", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono))
    {
        printk("申请gpio对象失败\n");
        return -ENXIO;
    }
    printk("申请gpio信息对象成功\n");

    return 0;
out5:
    //释放前一次提交成功的设备信息
    for(--i;i>=0;i--)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    class_destroy(cls);//释放目录
out4:
    cdev_del(cdev);
out3:
    unregister_chrdev_region(MKDEV(major,minor),3);
out2:
    kfree(cdev);
out1:
    return ret;

}

static void __exit mycdev_exit(void)
{
    //循环灭灯和释放gpio编号
    int i;
    for(i=0;i<3;i++){
        // 灭灯
        gpiod_set_value(gpiono[i], 0);
        // 释放gpio编号
        gpiod_put(gpiono[i]);
    }
}

module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用端程序代码

pro1.c

#include 
#include 
#include 
#include 
#include 
#include "head.h"

int main(int argc, const char *argv[])
{
	int a,b;
	char buf[128]={0};
	int fd=open("/dev/myled0",O_RDWR);
	if(fd<0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
	while(1){
		 //从终端读取
        printf("请输入对LED灯的控制:1(开灯) 0(关灯)");
		scanf("%d",&a);
		printf("请输入要控制的灯:1(LED1) 2(LED2) 3(LED3)");
		scanf("%d",&b);
		switch(a){
			case 1://开灯
				ioctl(fd,LED_ON,&b);
				break;
			case 0://关灯
				ioctl(fd,LED_OFF,&b);
				break;
		}
	}

	return 0;
}