通过platform总线驱动实现中断控制

任务要求

通过platform总线驱动实现
a.应用程序通过阻塞的io模型来读取number变量的值 
b.number是内核驱动中的一个变量 
c.number的值随着按键按下而改变（按键中断） 例如number=0 按下按键number=1 ,再次按下按键number=0 
 e.驱动中需要编写字符设备驱动 
 f.驱动中需要自动创建设备节点 
 g.这个驱动需要的所有设备信息放在设备树的同一个节点中

代码实现

驱动代码

#include 
#include
#include
#include
#include 
#include 
#include 
#include 
#include 
#include 
#include
#include 
#include
#include
#include
#include
#include

#define CNAME  "keyirq"
struct device_node *node;
struct device_node *node1;
struct resource *res;
struct gpio_desc *desc; 

unsigned int irqno;//接收软中断号
 char number = '0';

int count;
int minor=0;//次设备号从0开始
#if 1 
unsigned int major = 0;//动态申请
#else
unsigned int major = 500;//静态指定设备号
#endif
char kbuf[128]={};//定义数组用于存放和用户之间拷贝的数据
struct cdev *cdev;
struct class *cls;
struct device *dev;
struct gpio_desc *desc;
//定义队列头
wait_queue_head_t wq_head;
unsigned int condition=0;//判断是否有数据准备好的标识变量

//对应的是open()
int mycdev_open(struct inode *inode, struct file *file)
{
	printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
	return 0;
}
//read()
ssize_t mycdev_read(struct file *file, char __user  *ubuf, size_t size, loff_t *loff)
{

	//size参数是用户期待读到的字节长度
	int ret;
	wake_up_interruptible(&wq_head);
	if(file->f_flags&O_NONBLOCK)
	{
		//非阻塞
		return -EINVAL;
	}
	else{
		//阻塞
		ret=wait_event_interruptible(wq_head,condition);
		if(ret)
		{
			return ret;
		}
	}
	if(size>sizeof(kbuf))
		size=sizeof(kbuf);
	ret=copy_to_user(ubuf,&number,sizeof(number));
	if(ret)
	{
		printk("数据从内核向用户拷贝失败\n");
		return -EIO;
	}
	//condition=0;
	condition=0;

	return size;
}
//write()
ssize_t mycdev_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff)
{
	return size;
}
int mycdev_close(struct inode *inode, struct file *file)
{
	printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
	return 0;
}
//操作方法结构体的初始化
struct file_operations fops=
{
	.open=mycdev_open,
	.read=mycdev_read,
	.write=mycdev_write,
	.release=mycdev_close,
};
//中断处理函数
irqreturn_t irq_handler(int irq, void *dev)
{
	printk("key2 interrupt....%d...\n",number);
	number=number=='1'?'0':'1';	
	 //电位反转
     gpiod_set_value(desc,!gpiod_get_value(desc));
	//唤醒
	condition=1;
	wake_up_interruptible(&wq_head);

	return IRQ_HANDLED;
}

//定义compatible表                   
 struct of_device_id oftable[]={
      {.compatible="hqyj,platform",},
      {},
 };
int pdrv_remove(struct platform_device *pdr)
{
      printk("%s:%d\n",__FILE__,__LINE__);
      return 0;
}                                             

int pdrv_probe(struct platform_device *pdr)
 {
       printk("%s:%d\n",__FILE__,__LINE__);
       res=platform_get_resource(pdr,IORESOURCE_MEM,0);
       if(res==NULL)
       {
            printk("获取资源失败\n");
            return -ENODATA;
       }
       irqno=platform_get_irq(pdr,0);
       if(irqno<0)
       {
             printk("获取资源失败\n");
             return irqno;
       }
     printk("%#x    %d\n",res->start,irqno);                                      

     //获取GPIO编号
     desc=gpiod_get_from_of_node(pdr->dev.of_node,"led2",0,GPIOD_OUT_HIGH,NULL);
     if(IS_ERR(desc))
     {
      printk("获取GPIO编号失败\n");
      return PTR_ERR(desc);
     }
       return 0;
 }

//定义并初始化对象
struct platform_driver pdrv ={
      .probe=pdrv_probe,
      .remove=pdrv_remove,
      .driver={
          .name= "test",
          .of_match_table= oftable,//设备树匹配
      },
 };


//入口函数，当驱动安装的时候执行
static int __init mycdev_init(void)
{
	int ret,i;
	//分配对象
	dev_t devno;
	cdev=cdev_alloc();
	//注册对象
platform_driver_register(&pdrv);

	if(cdev==NULL)
	{
		printk("cdev alloc memory err\n");

		ret = -ENOMEM;
		goto ERR1;
	}
	printk("对象分配成功\n");
	//对象的初始化
	cdev_init(cdev,&fops);
	//设备号的申请

	if(major==0)//动态申请
	{
		ret=alloc_chrdev_region(&devno,minor,1,"keyirq");

		if(ret)
		{
			printk("动态申请设备号失败\n");
			goto ERR2;
		}
		major = MAJOR(devno);
		minor = MINOR(devno);
		printk("动态申请设备号成功\n");
	}
	else
	{
		ret=register_chrdev_region(MKDEV(major,minor),1,"keyirq");
		if(ret)
		{
			printk("静态申请设备号失败\n");
			goto ERR2;
		}
		printk("静态申请设备号成功\n");
	}
	//注册字符设备驱动
	ret=cdev_add(cdev,MKDEV(major,minor),1);
	if(ret)
	{
		printk("字符设备驱动注册失败\n");
		goto ERR3;
	}
	printk("注册字符设备驱动成功\n");

	//自动创建设备节点
	cls = class_create(THIS_MODULE,"keyirq1");
	if(IS_ERR(cls))
	{
		printk("创建逻辑节点目录失败\n");
		ret=PTR_ERR(cls);
		goto ERR4;
	}
	printk("创建逻辑节点目录成功\n");
	//向上提交节点信息
	dev = device_create(cls,NULL,MKDEV(major,0),NULL,"keyirq");
	if(IS_ERR(dev))
	{
		printk("创建逻辑节点失败\n");
		ret = PTR_ERR(dev);
		goto ERR5;
	}
		init_waitqueue_head(&wq_head);
		//解析设备树节点
    node=of_find_node_by_name(NULL,"keyirq");
    if(node==NULL)
    {
        printk("解析设备树节点失败\n");
        return EAGAIN;
    }
    printk("解析设备树节点成功\n");
	//根据设备树节点获取软中断号
	irqno=irq_of_parse_and_map(node,0);
	if(irqno==0)
	{
		printk("获取软中断号失败\n");
		return EINVAL;
	}
	printk("获取软中断号成功\n");
	//注册中断
	ret=request_irq(irqno,irq_handler,IRQF_TRIGGER_FALLING,"key2_inte",NULL);
	if(ret)
	{
		printk("注册中断失败\n");
		return ret;
	}
	printk("注册中断成功\n");


printk("创建逻辑节点成功\n");
return 0;
ERR5:
for(--i;i>=0;i--)
{
	device_destroy(cls,MKDEV(major,i));
}
class_destroy(cls);
ERR4:
cdev_del(cdev);
ERR3:
unregister_chrdev_region(MKDEV(major,minor),count);
ERR2:
kfree(cdev);
ERR1:
return ret;
}

static void __exit mycdev_exit(void)
{
	//1.销毁设备节点
         device_destroy(cls,MKDEV(major,0));
     class_destroy(cls);
    //2.注销字符设备驱动
    cdev_del(cdev);
    //3.释放设备号
    unregister_chrdev_region(MKDEV(major,minor),count);
    //4.释放动态申请的空间
    kfree(cdev);
    //注销中断
    free_irq(irqno,NULL);
	 //释放GPIO编号
    gpiod_set_value(desc,0);
    gpiod_put(desc);
	//注销
platform_driver_unregister(&pdrv);

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

测试代码

#include
#include
#include
#include
#include
#include
#include
#include 
//#include"myirq.h"

int main(int argc, char const *argv[])
{
    int fd=open("/dev/keyirq",O_RDWR);
    char number;
    if(fd<0)
    {

        printf("打开设备文件失败\n");
        exit(-1);
    }
    printf("设备文件打开成功\n");
    //在终端输入
    while(1)
    {
        read(fd,&number,sizeof(number));
    printf("number=%c\n",number);
    
    }
    close(fd);
    return 0;
}

分析思路

1

1.需要通过阻塞IO方式读取内核数据信息，所以在测试文件中调用read函数
内核中需要使用copy_to_user函数实现从内核到用户的数据拷贝

/read()
ssize_t mycdev_read(struct file *file, char __user  *ubuf, size_t size, loff_t *loff)
{

	//size参数是用户期待读到的字节长度
	int ret;
	wake_up_interruptible(&wq_head);
	if(file->f_flags&O_NONBLOCK)
	{
		//非阻塞
		return -EINVAL;
	}
	else{
		//阻塞
		ret=wait_event_interruptible(wq_head,condition);
		if(ret)
		{
			return ret;
		}
	}
	//把父进程拷贝到内核的数据再拷贝给子进程
	if(size>sizeof(kbuf))
		size=sizeof(kbuf);
	ret=copy_to_user(ubuf,&number,sizeof(number));
	if(ret)
	{
		printk("数据从内核向用户拷贝失败\n");
		return -EIO;
	}
	//condition=0;
	condition=0;

	return size;
}

2

number的值需要随着按键按下而改变（按键中断），所以在中断处理函数中，在唤醒之前对number进行0/1变换操作

//中断处理函数
irqreturn_t irq_handler(int irq, void *dev)
{
	printk("key2 interrupt....%d...\n",number);
	number=number=='1'?'0':'1';	
	 //电位反转
     gpiod_set_value(desc,!gpiod_get_value(desc));
	//唤醒
	condition=1;
	wake_up_interruptible(&wq_head);

	return IRQ_HANDLED;
}

3

在按下按键的时候需要同时将led1的状态取反
GPIO设备信息由platform总线从设备树中获取

int pdrv_probe(struct platform_device *pdr)
 {
       printk("%s:%d\n",__FILE__,__LINE__);
       res=platform_get_resource(pdr,IORESOURCE_MEM,0);
       if(res==NULL)
       {
            printk("获取资源失败\n");
            return -ENODATA;
       }
       irqno=platform_get_irq(pdr,0);
       if(irqno<0)
       {
             printk("获取资源失败\n");
             return irqno;
       }
     printk("%#x    %d\n",res->start,irqno);                                      

     //获取GPIO编号
     desc=gpiod_get_from_of_node(pdr->dev.of_node,"led2",0,GPIOD_OUT_HIGH,NULL);
     if(IS_ERR(desc))
     {
      printk("获取GPIO编号失败\n");
      return PTR_ERR(desc);
     }
       return 0;
 }