Linux设备驱动之Ioctl控制

int ioctl(int fd,unsigned long cmd,...);
/*
fd:文件描述符
cmd:控制命令
...:可选参数:插入*argp，具体内容依赖于cmd
*/

int (*ioctl) (struct inode *inode,struct file *filp,unsigned int cmd,unsigned long arg);
/*
inode与filp两个指针对应于应用程序传递的文件描述符fd，这和传递open方法的参数一样。
cmd 由用户空间直接不经修改的传递给驱动程序
arg 可选。
*/

| 设备类型 | 序列号 | 方向 | 数据尺寸 |
|----------|--------|------|-------- || bit | bit | bit |~ bit||----------|--------|------|-------- |

//nr为序号，datatype为数据类型,如int
_IO(type, nr ) //没有参数的命令
_IOR(type, nr, datatype) //从驱动中读数据
_IOW(type, nr, datatype) //写数据到驱动
_IOWR(type,nr, datatype) //双向传送

#define MEM_IOC_MAGIC 'm' //定义类型
#define MEM_IOCSET _IOW(MEM_IOC_MAGIC,0,int)
#define MEM_IOCGQSET _IOR(MEM_IOC_MAGIC, 1, int)

copy_from_user
copy_to_user
get_user
put_user

__get_user
__put_user

static inline int access_ok(int type, const void *addr, unsigned long size)
/*
type :是VERIFY_READ 或者VERIFY_WRITE用来表明是读用户内存还是写用户内存;
addr:是要操作的用户内存地址;
size:是操作的长度。如果ioctl需要从用户空间读一个整数，那么size参数就等于sizeof(int)；返回值：Access_ok返回一个布尔值：1，是成功（存取没问题）；0，是失败，ioctl返回-EFAULT；*/

switch(cmd)
{
case:
... ...
}

/*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_ */

static int mem_major = MEMDEV_MAJOR;module_param(mem_major, int, S_IRUGO);struct mem_dev *mem_devp; /*设备结构体指针*/struct cdev cdev; /*文件打开函数*/
int mem_open(struct inode *inode, struct file *filp)
{
struct mem_dev *dev; /*获取次设备号*/
int num = MINOR(inode->i_rdev); if (num >= MEMDEV_NR_DEVS)
return -ENODEV;
dev = &mem_devp[num]; /*将设备描述结构指针赋值给文件私有数据指针*/
filp->private_data = dev; return 0;
}/*文件释放函数*/
int mem_release(struct inode *inode, struct file *filp)
{
return 0;
}/*IO操作*/
int memdev_ioctl(struct inode *inode, struct file *filp,
unsigned int cmd, unsigned long arg)
{ int err = 0;
int ret = 0;
int ioarg = 0; /* 检测命令的有效性 */
if (_IOC_TYPE(cmd) != MEMDEV_IOC_MAGIC)
return -EINVAL;
if (_IOC_NR(cmd) > MEMDEV_IOC_MAXNR)
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;}/*文件操作结构体*/
static const struct file_operations mem_fops =
{
.owner = THIS_MODULE,
.open = mem_open,
.release = mem_release,
.ioctl = memdev_ioctl,
};/*设备驱动模块加载函数*/
static int memdev_init(void)
{
int result;
int i; dev_t devno = MKDEV(mem_major, 0); /* 静态申请设备号*/
if (mem_major)
result = register_chrdev_region(devno, 2, "memdev");
else /* 动态分配设备号 */
{
result = alloc_chrdev_region(&devno, 0, 2, "memdev");
mem_major = MAJOR(devno);
} if (result < 0)
return result; /*初始化cdev结构*/
cdev_init(&cdev, &mem_fops);
cdev.owner = THIS_MODULE;
cdev.ops = &mem_fops; /* 注册字符设备 */
cdev_add(&cdev, MKDEV(mem_major, 0), MEMDEV_NR_DEVS); /* 为设备描述结构分配内存*/
mem_devp = kmalloc(MEMDEV_NR_DEVS * sizeof(struct mem_dev), GFP_KERNEL);
if (!mem_devp) /*申请失败*/
{
result = - ENOMEM;
goto fail_malloc;
}
memset(mem_devp, 0, sizeof(struct mem_dev)); /*为设备分配内存*/
for (i=0; i < MEMDEV_NR_DEVS; i++)
{
mem_devp[i].size = MEMDEV_SIZE;
mem_devp[i].data = kmalloc(MEMDEV_SIZE, GFP_KERNEL);
memset(mem_devp[i].data, 0, MEMDEV_SIZE);
} return 0; fail_malloc:
unregister_chrdev_region(devno, 1); return result;
}/*模块卸载函数*/
static void memdev_exit(void)
{
cdev_del(&cdev); /*注销设备*/
kfree(mem_devp); /*释放设备结构体内存*/
unregister_chrdev_region(MKDEV(mem_major, 0), 2); /*释放设备号*/
}MODULE_AUTHOR("David Xie");
MODULE_LICENSE("GPL");module_init(memdev_init);
module_exit(memdev_exit);

#include <stdio.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>#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/memdev0",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;
}