以阻塞方式对IO文件进行读取(test.c读取，test2.c发送数据)
实验结果
执行test.c生成的pro1可执行文件，光标显示处于阻塞状态
执行test2.c生成的pro2可执行文件，test.c处打印 hello dhl
三级标题test.c
#include <stdlib.h>
#include <stdio.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[])
{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){memset(buf,0,sizeof(buf));//清空read(fd,buf,sizeof(buf)); //读取数据printf("buf:%s\n",buf);}close(fd);return 0;
}
三级标题test2.c
#include <stdlib.h>
#include <stdio.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[])
{char buf[128] = "hello dhl";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)); //写数据.模拟传感器获取到数据close(fd);return 0;
}三级标题myled0.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/uaccess.h>struct cdev *cdev; //字符设备空间首地址
unsigned int major=500; //静态申请设备号
unsigned int minor=0;//次设备号的起始值
dev_t devno; //动态申请设备号
struct class *cls; //接收注册结构体的地址
struct device *dev; //设备号
char kbuf[128] = {0}; //硬件数据
//定义等待队头
wait_queue_head_t wq_head; //等待队列
unsigned int condition = 0; //硬件准备信号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)
{int ret;if(sizeof(kbuf) < size)size = sizeof(kbuf);wait_event_interruptible(wq_head, condition); //进程切换为休眠状态ret = copy_to_user(ubuf, kbuf, size);if(ret){printk("copy_to_user failed\n");return -EIO;}printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);condition = 0; //下次事件还没准备好return 0;
}
ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *lof)
{int ret;if(sizeof(kbuf) < size)//判断用户空间的需求是否能被驱动满足，满足不了就给能给的最好的size = sizeof(kbuf);ret = copy_from_user(kbuf, ubuf, size);if(ret){printk("copy_from_user filed\n");return -EIO;}condition = 1; //表示硬件数据准备就绪wake_up_interruptible(&wq_head); //唤醒休眠的进程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,.read = mycdev_read,.write = mycdev_write,.release = mycdev_close,
};static int __init mycdev_init(void) //寄存器地址映射和初始化
{int ret; //ret返回错误码 //初始化等待队列头init_waitqueue_head(&wq_head);
/*// 映射物理地址vir_gpioe = ioremap(GPIOE, sizeof(gpio_t));if (vir_gpioe == NULL){printk("MODER寄存器映射失败\n");return -EFAULT;}vir_rcc = ioremap(RCC, 4);if (vir_rcc == NULL){printk("RCC寄存器映射失败\n");return -EFAULT;}vir_gpiof = ioremap(GPIOF, sizeof(gpio_t));if (vir_gpiof == NULL){printk("MODER寄存器映射失败\n");return -EFAULT;}printk("寄存器映射成功\n");
*///1.分配字符设备驱动对象空间 cdev_alloccdev=cdev_alloc(); //字符设备空间首地址if(cdev==NULL){printk("申请字符设备驱动对象空间失败\n");ret=-EFAULT;goto out1;}printk("字符设备驱动对象申请成功\n");//2.字符设备驱动对象部分初始化 cdev_initcdev_init(cdev,&fops);//3.申请设备号 register_chrdev_region/alloc_chrdev_regionif(major>0)//静态申请设备号{ret=register_chrdev_region(MKDEV(major,minor),1,"myled0"); //设备号需要是组合出来的,次设备数量，设备文件名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,"myled0"); //动态申请设备号，次设备号，设备数量，文件名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); //字符设备，设备号，设备数量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,"myled0"); //指向自身的指针，文件名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,0),NULL,"myled0"); //创建设备节点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");
/*(*vir_rcc) |= (0x3 << 4);// 寄存器初始化led1vir_gpioe->moder &= (~(0x3 << 20));vir_gpioe->moder |= (0x1 << 20);vir_gpioe->odr &= (~(0x1 << 10));printk("LED1硬件寄存器初始化成功\n");*/return 0;out5://销毁上面提交的设备信息device_destroy(cls,MKDEV(major,0));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)
{//1.销毁设备信息 device_destroydevice_destroy(cls,MKDEV(major,0));//2.销毁目录 class_destroyclass_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);
/*// 取消寄存器地址映射iounmap(vir_gpioe);iounmap(vir_rcc);iounmap(vir_gpiof);// 销毁设备节点信息device_destroy(cls, MKDEV(major, 0));// 销毁字符设备驱动class_destroy(cls);// 字符设备驱动的注销unregister_chrdev(major, "led0");
*/
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");
