1.生产设备节点

这里讲解的是杂项设备，杂项设备的主设备固定为10
misc源代码：“drivers/char/ misc.c，这个是在makefile中强制编译的

1.1杂项设备注册头文件

– include/linux/miscdevice.h
vim include/linux/miscdevice.h

struct miscdevice  {
        int minor;
        const char *name;
        const struct file_operations *fops;
        struct list_head list;
        struct device *parent;
        struct device *this_device;
        const char *nodename;
        mode_t mode;
};

extern int misc_register(struct miscdevice * misc);
extern int misc_deregister(struct miscdevice *misc);

代码添加

#define MISC_NAME  "hello_misc"//在/dev中显示的名字/


MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("TOPEET");


struct miscdevice hello_misc= {
        .minor=MISC_DYNAMIC_MINOR;//自动自动生产minor
        .name=MISC_NAME;
        .fops=;
  
};

int hello_probe(struct platform_device *pdev)
{
    
  misc_register(&hello_misc);
  printk(KERN_EMERG "hello_probe call \n");
  return 0;
  
}

int hello_remove(struct platform_device *pdev)
{

    misc_deregister(&hello_misc);
    printk(KERN_EMERG"remove call \n");
    return 0;
}

2 在misc中加入fs

include/linux/fs.h

vim include/linux/fs

/*
 * NOTE:
 * all file operations except setlease can be called without
 * the big kernel lock held in all filesystems.
 */
struct file_operations {
        struct module *owner;
        loff_t (*llseek) (struct file *, loff_t, int);
        ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
        ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
        ssize_t (*aio_read) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
        ssize_t (*aio_write) (struct kiocb *, const struct iovec *, unsigned long, loff_t);
        int (*readdir) (struct file *, void *, filldir_t);
        unsigned int (*poll) (struct file *, struct poll_table_struct *);
/* remove by cym 20130408 support for MT660.ko */
#if 0
//#ifdef CONFIG_SMM6260_MODEM
#if 1// liang, Pixtree also need to use ioctl interface...
        int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
#endif
#endif
/* end remove */
        long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
        long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
        int (*mmap) (struct file *, struct vm_area_struct *);
        int (*open) (struct inode *, struct file *);
        int (*flush) (struct file *, fl_owner_t id);
        int (*release) (struct inode *, struct file *);
        int (*fsync) (struct file *, int datasync);
        int (*aio_fsync) (struct kiocb *, int datasync);
        int (*fasync) (int, struct file *, int);
        int (*lock) (struct file *, int, struct file_lock *);
        ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
        unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
        int (*check_flags)(int);
        int (*flock) (struct file *, int, struct file_lock *);
        ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
        ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
        int (*setlease)(struct file *, long, struct file_lock **);
        long (*fallocate)(struct file *file, int mode, loff_t offset,
                          loff_t len);
/* add by cym 20130408 support for MT6260 and Pixtree */
#if defined(CONFIG_SMM6260_MODEM) || defined(CONFIG_USE_GPIO_AS_I2C)
        int (*ioctl) (struct inode *, struct file *, unsigned int, unsigned long);
#endif
/* end add */
};

#define IPERM_FLAG_RCU  0x0001

               

2.1填充fs

#include <linux/init.h>
#include <linux/module.h>


/*驱动注册的头文件，包含驱动的结构体和注册和卸载的函数*/
#include <linux/platform_device.h>


#include <linux/miscdevice.h>

#include <linux/fs.h>
#define DRIVER_NAME "hello"  //必须和设备注册的一致
#define MISC_NAME  "hello_misc"//在/dev中显示的名字/


MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("TOPEET");

 long hello_unlocked_ioctl(struct file *pfd, unsigned int cmd, unsigned long arg)
 {
printk(KERN_EMERG "fs unlocked_ioctl call file:%s cmd:%d  arg:%d \n",pfd,cmd,arg);
 return 0;
 }
 
 int hello_release(struct inode *nd, struct file *pfd)
 {
 printk(KERN_EMERG "fs release call nd:%s file: \n",nd,pfd);
 return 0;    
      
 }
  int hello_open(struct inode *nd, struct file *pfd)
  {
      
       printk(KERN_EMERG "fs open call nd:%s file: \n",nd,pfd);
 return 0;    
  }
 
struct file_operations hello_fs={
.owner=THIS_MODULE,
.open=hello_open,
.release=hello_release,
.unlocked_ioctl=hello_unlocked_ioctl,
};

struct miscdevice hello_misc={
        .minor=MISC_DYNAMIC_MINOR,
        .name=MISC_NAME,
        .fops=&hello_fs,
  
};

int hello_probe(struct platform_device *pdev)
{
    
  misc_register(&hello_misc);
  printk(KERN_EMERG "hello_probe call \n");
  return 0;
  
}

int hello_remove(struct platform_device *pdev)
{

    misc_deregister(&hello_misc);
    printk(KERN_EMERG"remove call \n");
    return 0;
}
void hello_shutdown(struct platform_device *pdev)
{
   printk(KERN_EMERG"shutdown call \n");
}
int hello_suspend(struct platform_device *pdev, pm_message_t state)
{
     printk(KERN_EMERG"suspend call \n");
    return 0;
}
int hello_resume(struct platform_device * pdev)
{
    
     printk(KERN_EMERG"resume call \n");
    return 0;
}

struct platform_driver  stu_hello={
        .probe=hello_probe,
        .remove=hello_remove,
        .shutdown=hello_shutdown,
        .suspend=hello_suspend,
        .resume=hello_resume,
       .driver={
           .name = DRIVER_NAME,
           .owner = THIS_MODULE,
       },
    
};

static int hello_init(void)
{
    int err;
    printk(KERN_EMERG "hello world enter\n");
    err=platform_driver_register(&stu_hello);
     printk(KERN_EMERG "register result:%d\n",err);
    return 0;
}

static void hello_exit(void)
{
    printk(KERN_EMERG "hello world exit\n");
    platform_driver_unregister(&stu_hello);

}
module_init(hello_init);
module_exit(hello_exit);

2.2运行结果 insmode 和 rmmod

中间在dev中可以看到hello_misc

ls /dev/

image.png

[root@iTOP-4412]# insmod /mnt/udisk/hello_driver.ko 
[ 3768.651034] hello world enter
[ 3768.660692] hello_probe call 
[ 3768.670667] register result:0



hello_driver 2109 0 - Live 0xbf000000
[root@iTOP-4412]# rmmod hello_driver
[ 4077.111126] hello world exit
[ 4077.113711] remove call 

2.3编写应用程序测试

打印头文件
– include <stdio.h>调用打印函数printf
• 应用中调用文件需要的头文件
– #include <sys/types.h>基本系统数据类型。系统的基本数据类型在 32 编译
环境中保持为 32 位值,并会在 64 编译环境中增长为 64 位值。
– #include <sys/stat.h>系统调用函数头文件。可以调用普通文件，目录，管
道，socket，字符，块的属性
– #include <fcntl.h>定义了open函数
– #include <unistd.h>定义了close函数
– #include <sys/ioctl.h>定义了ioctl函数

#include "stdio.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>//定义了open函数
#include <unistd.h>//定义了close函数
#include <sys/ioctl.h>//定义了ioctl函数


int main()
{
     char *device="/dev/hello_misc";
    int fd = open(device,O_RDWR|O_NDELAY);
    if(fd<0)
    {
        printf("open file %s err \n",device);
        
    }else
    {
        
        printf("open file %s seuccess \n",device);
        ioctl(fd,123,678);
        
    }


    
    
    close(fd);
    
}