http://www.cnblogs.com/geneil/archive/2011/12/04/2275372.html
驱动层
#include <linux/init.h>
#include <linux/module.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/uaccess.h>
/* 定义幻数 */
#define MEMDEV_IOC_MAGIC 'k'
/* 定义命令 */
#define MEMDEV_IOCPRINT _IO(MEMDEV_IOC_MAGIC, 1)
#define MEMDEV_IOCGETDATA _IOR(MEMDEV_IOC_MAGIC, 2, int) /*获取数据*/
#define MEMDEV_IOCSETDATA _IOW(MEMDEV_IOC_MAGIC, 3, int) /*设置数据*/
#define MEMDEV_IOC_MAXNR 3 /*一共定义了三条命令*/
MODULE_LICENSE("WQFDual BSD/GPL");
MODULE_AUTHOR("WQFDriver Monkey");
struct mmap_dev_t
{
dev_t dev_num;
char *dev_name;
struct class* cls;
char * cls_name;
struct cdev cdev;
};
struct mmap_dev_t mmap_dev =
{
.dev_name = "test_dev",
.cls_name = "test_class",
};
int my_open(struct inode *inode, struct file *filp)
{
printk(KERN_INFO"WQFmy_open()++\n");
printk(KERN_INFO"WQFmy_open()--\n");
printk("wQF===============================\n");
return 0;
}
ssize_t my_read(struct file *filp, char *buff, size_t count, loff_t *f_pos)
{
printk(KERN_INFO"my_read()++\n");
printk(KERN_INFO"my_read()--\n");
return 0;
}
ssize_t my_write(struct file *filp, const char *buff, size_t count, loff_t *f_pos)
{
printk(KERN_INFO"buff is :\n %s", buff);
printk(KERN_INFO"my_write()--\n");
return count;
}
int my_ioctl(struct inode *inode, struct file *filp, \
unsigned int cmd, unsigned long arg) /*IOCTL的驱动函数*/
{
int err = 0;
int ret = 0;
int ioarg = 0;
/* 检测命令的有效性 */
if (_IOC_TYPE(cmd) != MEMDEV_IOC_MAGIC) /*检测是不是我们声明的幻数*/
return -EINVAL;
if (_IOC_NR(cmd) > MEMDEV_IOC_MAXNR) /*检测是不是超出了我们的命令个数*/
return -EINVAL;
/* 根据命令类型，检测参数空间是否可以访问 */
if (_IOC_DIR(cmd) & _IOC_READ)
err = !access_ok(VERIFY_WRITE, (void *)arg, _IOC_SIZE(cmd));
else if (_IOC_DIR(cmd) & _IOC_WRITE)
err = !access_ok(VERIFY_READ, (void *)arg, _IOC_SIZE(cmd));
if (err)
return -EFAULT;
/* 根据命令，执行相应的操作 */
switch(cmd) {
/* 打印当前设备信息 */
case MEMDEV_IOCPRINT:
printk("<--- CMD MEMDEV_IOCPRINT Done--->\n\n");
break;
/* 获取参数 */
case MEMDEV_IOCGETDATA:
ioarg = 1101;
ret = __put_user(ioarg, (int *)arg);
break;
/* 设置参数 */
case MEMDEV_IOCSETDATA:
ret = __get_user(ioarg, (int *)arg);
printk("<--- In Kernel MEMDEV_IOCSETDATA ioarg = %d --->\n\n",ioarg);
break;
default:
return -EINVAL;
}
return ret;
}
struct file_operations mmap_opt =
{
.owner = THIS_MODULE,
.open = my_open,
.read = my_read,
.write = my_write,
.unlocked_ioctl = my_ioctl,
/* linux2.6.29和linux2.6.38的内核在file_operations结构发生了变化，
否则在linux2.6.38内核中，继续使用.ioctl成员，编译时就会报错：
error: unknown field 'ioctl' specified in initializer，struct file_operations结构体定义在include/linux/fs.h文件中。*/
};
static int wqfmmap_init(void)
{
int err = 0;
printk("mmap_init()++\n");
//dynamic alloc device number
if(0 != (err = alloc_chrdev_region
(&mmap_dev.dev_num, 0,3, mmap_dev.dev_name))) /*自动分配主次设备号*/
goto alloc_chrdev_region_err;
printk("Wmajor = %d, Wminor = %d\n",
MAJOR(mmap_dev.dev_num),MINOR(mmap_dev.dev_num));/*从设备编号里抽取出主次设备号*/
//create class
mmap_dev.cls = class_create(THIS_MODULE,mmap_dev.cls_name);
if(IS_ERR(mmap_dev.cls))
goto class_create_err;
//create character device
device_create(mmap_dev.cls,NULL,mmap_dev.dev_num,&mmap_dev,"wfdevice");/*创建字符设备 在dev/下面会生成这个设备文件*/
//activate character driver
cdev_init(&mmap_dev.cdev, &mmap_opt);/*file_operations 字符设备操作指针*/
mmap_dev.cdev.owner = THIS_MODULE;
err = cdev_add(&mmap_dev.cdev,mmap_dev.dev_num,1);
if(err)
goto cdev_add_err;
printk("mmap_init()--\n");
return 0;
cdev_add_err:
device_destroy(mmap_dev.cls, mmap_dev.dev_num);
class_destroy(mmap_dev.cls);
class_create_err:
unregister_chrdev_region(mmap_dev.dev_num,3);
alloc_chrdev_region_err:
return (-1);
}
static void wqfmmap_exit(void)
{
printk(KERN_INFO"mmap_exit()++\n");
cdev_del(&mmap_dev.cdev);
device_destroy(mmap_dev.cls, mmap_dev.dev_num);
class_destroy(mmap_dev.cls);
unregister_chrdev_region(mmap_dev.dev_num,3);
printk(KERN_INFO"mmap_exit()--\n");
}
module_init(wqfmmap_init);
module_exit(wqfmmap_exit);
应用层
wqftest.c
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h> /*加入这个头 close才不会出错*/
#include "memdev.h" /* 包含命令定义 */
int main()
{
int fd = 0;
int cmd;
int arg = 0;
char Buf[4096];
/*打开设备文件*/
fd = open("/dev/wfdevice",O_RDWR);
if (fd < 0)
{
printf("Open Dev Mem0 Error!\n");
return -1;
}
/* 调用命令MEMDEV_IOCPRINT */
printf("<--- Call MEMDEV_IOCPRINT --->\n");
cmd = MEMDEV_IOCPRINT;
if (ioctl(fd, cmd, &arg) < 0)
{
printf("Call cmd MEMDEV_IOCPRINT fail\n");
return -1;
}
/* 调用命令MEMDEV_IOCSETDATA */
printf("<--- Call MEMDEV_IOCSETDATA --->\n");
cmd = MEMDEV_IOCSETDATA;
arg = 2007;
if (ioctl(fd, cmd, &arg) < 0)
{
printf("Call cmd MEMDEV_IOCSETDATA fail\n");
return -1;
}
/* 调用命令MEMDEV_IOCGETDATA */
printf("<--- Call MEMDEV_IOCGETDATA --->\n");
cmd = MEMDEV_IOCGETDATA;
if (ioctl(fd, cmd, &arg) < 0)
{
printf("Call cmd MEMDEV_IOCGETDATA fail\n");
return -1;
}
printf("<--- In User Space MEMDEV_IOCGETDATA Get Data is %d --->\n\n",arg);
close(fd);
return 0;
}
memdev.h
#ifndef _MEMDEV_H_
#define _MEMDEV_H_
#include "linux/ioctl.h"
#ifndef MEMDEV_MAJOR
#define MEMDEV_MAJOR 0 /*预设的mem的主设备号*/
#endif
#ifndef MEMDEV_NR_DEVS
#define MEMDEV_NR_DEVS 2 /*设备数*/
#endif
#ifndef MEMDEV_SIZE
#define MEMDEV_SIZE 4096
#endif
/*mem设备描述结构体*/
struct mem_dev
{
char *data;
unsigned long size;
};
/* 定义幻数 */
#define MEMDEV_IOC_MAGIC 'k'
/* 定义命令 */
#define MEMDEV_IOCPRINT _IO(MEMDEV_IOC_MAGIC, 1)
#define MEMDEV_IOCGETDATA _IOR(MEMDEV_IOC_MAGIC, 2, int)
#define MEMDEV_IOCSETDATA _IOW(MEMDEV_IOC_MAGIC, 3, int)
#define MEMDEV_IOC_MAXNR 3
#endif /* _MEMDEV_H_ */
Makefile
wqftest.o : wqftest.c memdev.h g++ -c wqftest.c -o wqftest.o