IOCTL命令字符设备驱动

#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_ */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#include "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;
}