作业：
基于platform实现

添加设备树节点
irq_led{
compatible = “hqyj,irq_led”; //用于获取节点
interrupt-parent = <&gpiof>; //引用父节点
interrupts = <9 0>; //这个节点引入的中断管脚
led1=<&gpioe 10 0>;
};
1.驱动端

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/uaccess.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
/*
    irq_led{
        compatible = "hqyj,irq_led";      //用于获取节点
        interrupt-parent = <&gpiof>;  //引用父节点
        interrupts = <9 0>; //这个节点引入的中断管脚
        led1=<&gpioe 10 0>;
    };
*/
#define CNAME "irq_led"

int major;
struct class *cls;
struct device *dev;
wait_queue_head_t wq;
unsigned int condition=0;
unsigned int status=0;
struct device_node *node;
struct gpio_desc *desc;
unsigned int irqno;
struct resource *res

irqreturn_t irq_led_handle(int irq, void *dev)
{
    status = gpiod_get_value(desc);
    status = !status;
    gpiod_set_value(desc,status);

    condition=1;
    wake_up_interruptible(&wq);

    return IRQ_HANDLED;
}
int irq_led_open(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
ssize_t irq_led_read(struct file *file, 
    char __user *ubuf, size_t size, loff_t *offs)
{
    int ret;
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    if(file->f_flags & O_NONBLOCK){
        //非阻塞
        return -EINVAL;
    }else{
        //阻塞
        ret = wait_event_interruptible(wq,condition);
        if(ret < 0){
            printk("receive signal....\n");
            return ret;
        }
    }
    //将数据拷贝到用户空间
    if(size > sizeof(status)) size = sizeof(status);
    ret = copy_to_user(ubuf,(void *)&status,size);
    if(ret){
        printk("copy data to user error\n");
        return -EIO;
    }

    //4.将条件清零
    condition = 0;

    return size;
}
int irq_led_close(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;
}
struct file_operations fops = {
    .open = irq_led_open,
    .read = irq_led_read,
    .release = irq_led_close,
};

int pdrv_probe(struct platform_device *pdev)
{
    int ret;
    //1.注册字符设备驱动
    major = register_chrdev(0,CNAME,&fops);
    if(major < 0){
        printk("register char device driver error\n");
        ret = major;
        goto ERR1;
    }
    //2.创建设备节点
    cls = class_create(THIS_MODULE,CNAME);
    if(IS_ERR(cls)){
        printk("class create error\n");
        ret = PTR_ERR(cls);
        goto ERR2;
    }
    dev = device_create(cls,NULL,MKDEV(major,0),NULL,CNAME);
    if(IS_ERR(dev)){
        printk("device create error\n");
        ret = PTR_ERR(dev);
        goto ERR3;
    }
    //3.初始化等待队列头
    init_waitqueue_head(&wq);
    //4.解析设备树节点，申请使用的中断和led
    node = of_find_node_by_path("/irq_led");
    if(node == NULL){
        printk("get node error");
        ret = -EAGAIN;
        goto ERR4;
    }
    //获取gpio结构体信息
    desc = gpiod_get_from_of_node(node,"led1",0,GPIOD_OUT_LOW,NULL);
    if(IS_ERR(desc)){
        printk("get gpiod error\n");
        ret = PTR_ERR(desc);
        goto ERR4;
    }
//获取软中断号
    irqno = irq_of_parse_and_map(node,0);
    if(irqno == 0){
        printk("irq get number error\n");
        ret = -EAGAIN;
        goto ERR5;
    }
//注册中断
    ret = request_irq(irqno,irq_led_handle,IRQF_TRIGGER_FALLING,CNAME,NULL);
    if(ret){
        printk("request irq error\n");
        goto ERR5;
    }

    return 0;
ERR5:
    gpiod_put(desc);
ERR4:
    device_destroy(cls,MKDEV(major,0));
ERR3:
    class_destroy(cls);
ERR2:
    unregister_chrdev(major,CNAME);
ERR1:
    return ret;
}
int pdrv_remove(struct platform_device *pdev)
{
    free_irq(irqno,NULL);
    gpiod_put(desc);
    device_destroy(cls,MKDEV(major,0));
    class_destroy(cls);
    unregister_chrdev(major,CNAME);
}
struct of_device_id oftable[]={
    {.compatible="hqyj,irq_led",},
    {.compatible="hqyj,myplatform",},
    {.compatible="hqyj,myplatform",},
    {},
};
struct platform_driver pdrv={
    .probe=pdrv_probe,
    .remove=pdrv_remove,
    .driver={
        .name="aaaaa",
        .of_match_table=oftable,
    },
};
 
//一键注册宏
module_platform_driver(pdrv);

MODULE_LICENSE("GPL");

2.应用程序

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

int main(int argc, const char* argv[])
{
    int fd;
    int status;

    if ((fd = open("/dev/irq_led", O_RDWR)) == -1) {
        perror("open error");
        exit(EXIT_FAILURE);
    }

    while (1) {
        read(fd, &status, sizeof(status));
        printf("status = %d\n", status);
    }
    close(fd);
    return 0;
}