版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/qq_27312943/article/details/79187357
1 ioctl设备操作
参考书籍 《嵌入式Linux驱动开发教程》 华清远见嵌入式学院
2 虚拟串口中添加unlocked_ioctl后的代码
vser.h
/*vser.h*/
#ifndef _VSER_H
#define _VSER_H
struct option{
unsigned int datab;
unsigned int parity;
unsigned int stopb;
};
#define VS_MAGIC 's' /*幻数*/
#define VS_SET_BAUD _IOW(VS_MAGIC,0,unsigned int)
#define VS_GET_BAUD _IOW(VS_MAGIC,1,unsigned int)
#define VS_SET_FFMT _IOW(VS_MAGIC,2,struct option)
#define VS_GET_FFMT _IOW(VS_MAGIC,3,struct option)
#endif
vser.c
/***************************************
高级I/O操作
ioctl设备操作
*****************************************/
/*vser.c*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/kfifo.h>
#include <linux/ioctl.h>
#include <linux/uaccess.h>
#include "vser.h"
#define VSER_MAJOR 256
#define VSER_MINOR 0
#define VSER_DEV_CNT 1
#define VSER_DEV_NAME "vser"
struct vser_dev {
unsigned int baud; /*波特率*/
struct option opt; /*帧格式信息*/
struct cdev cdev;
};
DEFINE_KFIFO(vsfifo, char, 32);
static struct vser_dev vsdev;
static int vser_open(struct inode *inode, struct file *filp)
{
return 0;
}
static int vser_release(struct inode *inode, struct file *filp)
{
return 0;
}
static ssize_t vser_read(struct file *filp, char __user *buf, size_t count, loff_t *pos)
{
int ret;
unsigned int copied = 0;
ret = kfifo_to_user(&vsfifo, buf, count, &copied);
return ret == 0 ? copied : ret;
}
static ssize_t vser_write(struct file *filp, const char __user *buf, size_t count, loff_t *pos)
{
int ret;
unsigned int copied = 0;
ret = kfifo_from_user(&vsfifo, buf, count, &copied);
return ret == 0 ? copied : ret;
}
static long vser_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
if(_IOC_TYPE(cmd) != VS_MAGIC)
{
return -ENOTTY;
}
switch(cmd)
{
case VS_SET_BAUD:
vsdev.baud=arg;
break;
case VS_GET_BAUD:
arg=vsdev.baud;
break;
case VS_SET_FFMT:
if( copy_from_user(&vsdev.opt,(struct option __user*)arg,sizeof(struct option)) )
return -EFAULT;
break; /*这里的break千万不要忘记加*/
case VS_GET_FFMT:
if( copy_to_user((struct option __user*)arg,&vsdev.opt,sizeof(struct option)) )
return -EFAULT;
break;
default:
return -ENOTTY;
}
return 0;
}
static struct file_operations vser_ops = {
.owner = THIS_MODULE,
.open = vser_open,
.release = vser_release,
.read = vser_read,
.write = vser_write,
.unlocked_ioctl = vser_ioctl,
};
static int __init vser_init(void)
{
int ret;
dev_t dev; /*设备号*/
dev = MKDEV(VSER_MAJOR, VSER_MINOR);
/*注册字符设备*/
ret = register_chrdev_region(dev, VSER_DEV_CNT, VSER_DEV_NAME);
if (ret)
goto reg_err;
cdev_init(&vsdev.cdev, &vser_ops);
vsdev.cdev.owner = THIS_MODULE;
vsdev.baud = 115200;
vsdev.opt.datab = 8;
vsdev.opt.parity = 0; /*奇偶位*/
vsdev.opt.stopb = 1;
/*cdev对象初始化以后,就要添加到内核中的cdev_map散列表中 */
ret = cdev_add(&vsdev.cdev, dev, VSER_DEV_CNT);
if (ret)
goto add_err;
return 0;
add_err:
unregister_chrdev_region(dev, VSER_DEV_CNT);
reg_err:
return ret;
}
/*卸载函数*/
static void __exit vser_exit(void)
{
dev_t dev;
dev = MKDEV(VSER_MAJOR, VSER_MINOR);
cdev_del(&vsdev.cdev);
unregister_chrdev_region(dev, VSER_DEV_CNT);
}
module_init(vser_init);
module_exit(vser_exit);
测试文件
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <errno.h>
#include "vser.h"
int main(int argc, char *argv[])
{
int fd;
int ret;
unsigned int baud;
struct option opt = {8,2,1};
fd = open("/dev/vser0", O_RDWR);
if (fd == -1)
{
printf("open file error\n");
goto fail;
}
baud = 9600;
ret = ioctl(fd, VS_SET_BAUD, baud);
if (ret == -1)
{
printf("ioctl(fd, VS_SET_BAUD, baud) error\n");
goto fail;
}
ret = ioctl(fd, VS_GET_BAUD, baud);
if (ret == -1)
goto fail;
ret = ioctl(fd, VS_SET_FFMT, &opt);
if (ret == -1)
goto fail;
ret = ioctl(fd, VS_GET_FFMT, &opt);
if (ret == -1)
goto fail;
printf("baud rate: %d\n", baud);
printf("frame format: %d%c%d\n", opt.datab, opt.parity == 0 ? 'N' : \
opt.parity == 1 ? 'O' : 'E', \
opt.stopb);
close(fd);
exit(EXIT_SUCCESS);
fail:
perror("ioctl test");
exit(EXIT_FAILURE);
}
3 运行结果