如何在加载设备驱动程序的内核模块时自动在/dev 中创建设备? [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，作为我的第一次尝试，我正在尝试开发具有以下文件选项的字符设备驱动程序，
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 在字符设备下列出了驱动程序，但我在 /中找不到它开发.Google 搜索建议使用 mknod 在 /dev 中创建一个设备并将其与驱动程序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.
我应该怎么做才能让内核模块加载时设备出现在/dev中?我尝试了旧版 (register_chrdev) 和新版 (cdev_init & cdev_add) 来注册设备，但都没有奏效.
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
静态结构类c_dev;
static struct class c_dev;
在驱动的 __init 函数中添加以下 API
- cl = class_create(THIS_MODULE,"x");
其中 x - 加载驱动程序时显示在/sys/class/中的名称.
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 期间初始化的第一个设备编号的变量，用于为驱动程序动态分配主编号
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
如需进一步参考，请访问链接 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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