IO多路复用（select模型实现监控两个设备：自定义设备和鼠标设备）

1、驱动程序

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
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;
unsigned int condition=0;
//定义一个等待队列头
wait_queue_head_t wq_head;
// 封装操作方法
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)
{
    unsigned long ret;
    if (size > sizeof(kbuf)) // 用户空间期待读取的大小内核满足不了，那就给内核支持的最大大小
        size = sizeof(kbuf);
        if(file->f_flags&O_NONBLOCK)//非阻塞IO
        {}
        else{
            //wait_event_interruptible(wq_head,condition);
        }
    ret = copy_to_user(ubuf, kbuf, size);
    if (ret)
    {
        printk("copy_to_user err\n");
        return -EIO;
    }
    condition=0;
    return 0;
}
ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *lof)
{
    unsigned long ret;
    if (size > sizeof(kbuf)) // 用户空间期待读取的大小内核满足不了，那就给内核支持的最大大小
        size = sizeof(kbuf);
    ret = copy_from_user(kbuf, ubuf, size);

    if (ret)
    {
        printk("copy_from_user err\n");
        return -EIO;
    }
    condition=1;
    wake_up_interruptible(&wq_head);
    
    return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    return 0;
}
//封装POLL方法
__poll_t mycdev_poll(struct file *file,struct poll_table_struct *wait)
{
    __poll_t mask=0;
    //向上提交等待队列头
    poll_wait(file,&wq_head,wait);
    //根据事件是否发生给一个合适的返回值
    if(condition)
    {
        mask=POLLIN;
    }
    return mask;
}
struct file_operations fops = {
    .open = mycdev_open,
    .read = mycdev_read,
    .write = mycdev_write,
    .poll = mycdev_poll,
    .release = mycdev_close,
};

static int __init mycdev_init(void)
{
    init_waitqueue_head(&wq_head);
    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");
    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)
{  //取消地址映射
    
    //注销字符设备驱动
    //释放节点信息
    int i;
    for(i=0;i<3;i++)
    {
        device_destroy(cls,MKDEV(major,i));
    }
    //销毁目录
    class_destroy(cls);
    //注销驱动对象
    cdev_del(cdev);
    //释放设备号
    unregister_chrdev_region(MKDEV(major,minor),3);
    //释放对象空间
    kfree(cdev);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

2、测试程序鼠标设备事件

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


int main(int argc, char const *argv[])
{
    
    char buf[128] = {0};
    int fd1,fd2;
     fd1 = open("/dev/input/mouse0", O_RDWR);
    if (fd1 < 0)
    {
        printf("打开鼠标设备文件失败\n");
        exit(-1);
    }
    fd2 = open("/dev/myled0",O_RDWR);
    if(fd2 < 0)
    {
        printf("打开设备文件失败\n");
    }
    //定义事件集合
    fd_set readfds;
    while (1)
    {
        //清空事件集合
        FD_ZERO(&readfds);
        //将要监听的文件描述符添加到刻度集合
        FD_SET(fd1,&readfds);
        FD_SET(fd2,&readfds);
        //等待事件就绪
        printf("%s\n",buf);
        int ret = select(fd2+1,&readfds,NULL,NULL,NULL);
        if(ret<0)
        {
            printf("select err\n");
            exit(-1);
        }
        //判断事件是否发生
        //没发生事件会清除刻度集合，只需要判断文件描述符是否在集合中即可
        if(FD_ISSET(fd1,&readfds))
        {
            read(fd1,buf,sizeof(buf));
            printf("鼠标事件发生%s\n",buf);
        }
        if(FD_ISSET(fd2,&readfds))
        {
            read(fd2,buf,sizeof(buf));
            printf("自定义设备发生%s\n",buf);
        }
    }


    close(fd1);
    close(fd2);

    return 0;
}

 3、自定义事件设备

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


int main(int argc, char const *argv[])
{
    
    char buf[128] = {"hello world"};
    int fd = open("/dev/myled0", O_RDWR);
    if (fd < 0)
    {
        printf("打开设备文件失败\n");
        exit(-1);
    }
    write(fd,buf,sizeof(buf));

    close(fd);

    return 0;
}

 4测试结果