如何在为设备驱动程序加载内核模块后在/dev中自动创建设备? [英] How to create a device in /dev automatically upon loading of the kernel module for a device driver?

问题描述

我正在尝试开发Linux设备驱动程序，并且第一次尝试是开发具有以下文件选项的char设备驱动程序，

I am attempting to develop Linux device drivers and as my first attempt I am trying to develop a char device driver that has the following file options,

struct file_operations fops{  
.open=open_fun,  
.release=release_fun,  
.write=write_fun,  
.read=read_fun,  
};  

当我使用insmod加载驱动程序时，我看到/proc/devices列出了char设备下的驱动程序，但是在/dev中找不到它. Google搜索建议使用mknod在/dev中创建设备并将其与驾驶员的主要和次要相关联.但是，即使以超级用户身份执行此操作，也会导致权限被拒绝"错误.

When I load the driver using insmod, I see that /proc/devices lists the driver under char devices but I can't find it in /dev. A Google search suggested use of mknod to create a deivce in /dev and associate it with the driver's major and minor. However, an attempt to do so resulted in "Permission denied" error even when done as a super user.

加载内核模块后，我应该怎么做才能使设备出现在/dev中?我尝试了较旧(register_chrdev)和较新版本(cdev_init & cdev_add)的设备注册，但均无效果.

What should I do to make the device appear in /dev when the kernel module is loaded? I tried both the older (register_chrdev) and the newer version (cdev_init & cdev_add) of registering the device but none of them works.

谢谢，
米尔

推荐答案

• 包括头文件 linux/device.h 和 linux/kdev_t.h

  静态结构体类c_dev;

  static struct class c_dev;

  在驱动程序的__init函数内部添加以下API

  • cl = class_create(THIS_MODULE，"x");

  其中x-加载驱动程序时在/sys/class/中显示的名称.

  where x - Name to be displayed inside /sys/class/ when driver is loaded.

  • 使用device_create()内核api和device_create(cl，NULL，dev，NULL，"d");

  其中d-要在/dev下创建的设备文件.

  where d - device file to be created under /dev.

  其中dev是在使用 alloc_chrdev_region API为驱动程序动态分配主号期间初始化的第一个设备号的变量

  where dev is variable for the first device number that is initialized during the usage of alloc_chrdev_region API for dynamic allocation of major number for the driver

  有关更多参考，请通过链接 http://opensourceforu .com/2011/04/character-device-files-creation-operations/

  For Further reference please go through the link http://opensourceforu.com/2011/04/character-device-files-creation-operations/

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