要求：

现象

按下key1 led1灯的状态取反，number的值取反，然后应用程序打印从内核读到的number的值

应用程序test.c

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
int main(int argc, char const *argv[])
{
	int fd;
	char buf[10]={0};		
	fd = open("/dev/myled",O_RDWR);
	if(fd < 0)
	{
		printf("打开设备文件失败\n");
		exit(-1);
	}  
	while(1)
	{
		memset(buf,0,sizeof(buf));
		read(fd,buf,sizeof(buf));
		printf("buf[0]=%d\n",buf[0]);
	}  
	close(fd);
	return 0;
}

驱动程序job.c

#include <linux/init.h>
#include <linux/module.h>
#include<linux/fs.h>
#include<linux/device.h>
#include<linux/cdev.h>
#include<linux/slab.h>
#include <linux/io.h>
#include<linux/of.h>
#include<linux/gpio.h>
#include<linux/of_gpio.h>
#include <linux/interrupt.h>
#include <linux/of_irq.h>
#include <linux/uaccess.h>
struct cdev *cdev;//字符设备驱动对象空间首地址
unsigned int major=200;//主设备号
unsigned int minor=0;//次设备号的起始值
dev_t devno;//设备号变量
char kbuf[128]={0};
struct class *cls;//存放向上提交目录的返回值
struct device *dev;//存放向上提交设备节点信息结构体
struct device_node *dnode;//设备数节点信息结构体
struct gpio_desc *gpiono;//GPIO信息结构体
char number = 0;
unsigned int irqno;//获取中断号
wait_queue_head_t wq_head;//定义一个等待队列头
unsigned int condition=0;
int mycdev_open(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{
	//size参数是用户期待读到的字节长度
    int ret;
    //把内核的数据再拷贝给进程
    if(size>sizeof(kbuf))
    size=sizeof(kbuf);
	kbuf[0] = number;
	//将进程切换为可中断的休眠状态
	wait_event_interruptible(wq_head,condition);

    ret=copy_to_user(ubuf,kbuf,size);
    if(ret)
    {
        printk("数据从内核向用户拷贝失败\n");
        return -EIO;
    }
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
	condition = 0;
    return 0;
}
ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *lof)
{   
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    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 =
{
    .read = mycdev_read,
	.open = mycdev_open,
	.write = mycdev_write,
	.release = mycdev_close,
};
//中断处理函数
irqreturn_t myirq_handler(int irqno, void *dev_id)
{
    printk("key1 interrupt\n");
	number = !number;
	condition = 1;
	gpiod_set_value(gpiono,!gpiod_get_value(gpiono));
	wake_up_interruptible(&wq_head);
    return IRQ_HANDLED; 
}
static int __init mycdev_init(void)
{
	int ret;
	//初始化等待队列头
	init_waitqueue_head(&wq_head);
    //1.分配字符设备驱动对象空间  cdev_alloc
    cdev = cdev_alloc();
    if (!cdev) {
        printk(KERN_ALERT "cdev_alloc failed\n");
        return -ENOMEM;
    }
    printk("字符设备驱动对象空间申请成功\n");
    //2.字符设备驱动对象部分初始化  cdev_init
    cdev_init(cdev, &fops);
    //3.申请设备号  register_chrdev_region/alloc_chrdev_region
    if(major>0)//静态申请设备号
    {
        ret=register_chrdev_region(MKDEV(major,minor),1,"myled");
        if(ret)
        {
            printk("静态指定设备号失败\n");
            goto out2;
        }
    }
    else//动态申请设备号
    {
        ret=alloc_chrdev_region(&devno,minor,1,"myled");
        if(ret)
        {
            printk("动态申请设备号失败\n");
            goto out2;
        }
        major=MAJOR(devno);//根据设备号得到主设备号
        minor=MINOR(devno);//根据设备号得到次设备号
    }
    printk("申请设备号成功\n");
    //4.注册字符设备驱动对象  cdev_add()
    ret=cdev_add(cdev,MKDEV(major,minor),1);
    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");
    //5.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");
        ret=-PTR_ERR(cls);
		goto out4;
	}
	printk("向上提交目录成功\n");
	//6.向上提交设备节点
	dev=device_create(cls,NULL,MKDEV(major,minor),NULL,"myled");
	if(IS_ERR(dev))
	{
		printk("向上提交节点信息失败\n");
		ret=-PTR_ERR(dev);
		goto out5;
	}
	printk("向上提交设备节点信息成功\n");
	//解析led灯的设备树节点
	dnode=of_find_node_by_path("/myleds");
	if(dnode==NULL)
	{
		printk("解析设备树节点失败\n");
		return -ENXIO;
	}
	printk("解析设备树节点成功\n");
	//根据设备树节点解析led1 gpio结构体并向内核注册
	gpiono=gpiod_get_from_of_node(dnode,"led1",0,GPIOD_OUT_LOW,NULL); 
	if(IS_ERR(gpiono))
	{
		printk("申请gpio失败\n");
		return -PTR_ERR(gpiono);
	}
    //解析key设备树节点
    dnode=of_find_node_by_name(NULL,"mykeys");
    if(dnode==NULL)
    {
        printk("解析设备树节点失败\n");
        return -ENXIO;
    }
    printk("设备树节点解析成功\n");
	//获取软中断号
    irqno=irq_of_parse_and_map(dnode,0);
    if(!irqno)
    {
        printk("软中断号获取失败\n");
        return -ENOMEM;
    }
	printk("软中断号获取成功irqno=%d\n",irqno);
    //注册中断
    ret=request_irq(irqno,myirq_handler,IRQF_TRIGGER_FALLING,"key1",NULL);
    if(ret)
    {
        printk("注册驱动失败\n");
        return ret;
    }
    printk("key1中断注册成功\n");
	return 0;
out5:
	//销毁上面提交的设备信息
	device_destroy(cls,MKDEV(major,minor));
	class_destroy(cls);
out4:
	cdev_del(cdev);
out3:
    unregister_chrdev_region(MKDEV(major,minor),1);
out2:
    kfree(cdev);
out1:
    return ret;
}
static void __exit mycdev_exit(void)
{
 	//注销中断
    free_irq(irqno,NULL);
	//灭灯，注销gpio信息
	gpiod_set_value(gpiono,0);
	gpiod_put(gpiono);

	//1.销毁设备信息  device_destroy
	device_destroy(cls,MKDEV(major,minor));
	//2.销毁目录  class_destroy
    class_destroy(cls);
    //3.注销对象  cdev_del()
    cdev_del(cdev);
    //4.释放设备号   unregister_chrdev_region()
    unregister_chrdev_region(MKDEV(major,minor),1);
    //5.释放对象空间  kfree()
    kfree(cdev);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");