Compilation of simple character device drivers

Each character device in Linux has a struct cdev
Structure, so writing the character device driver is to fill in the structure.

The struct is as follows:

Linux-2.6.22/include/Linux/cdev. h

Struct cdev {

Struct kobject kobj ;//
Each cdev
All are kobject

Struct module * owner ;//
Pointing to implementation-driven modules

Const struct file_operations * OPS ;//
How to manipulate this character Device File

Struct list_head list ;//
And cdev
Inode-> I _devices of the corresponding character Device File
Linked List Header

Dev_t dev ;//
Start device ID

Unsigned int count ;//
Device range number size

};

General process:

Register a character device:

Apply for a device number	Register_chrdev_region/alloc_chrdev_region
Initialize the cdev structure of the device.	Cdev_init, cdev. Owner, cdev_ops
Register character Devices	Cdev_add ();
Allocate memory for the device description Structure	Kmalloc
Allocate memory for devices	Mem_devp.data = kmalloc ();

 

Detach a character device:

Cancel a device	Cdev_del (& cdev );
Release Device struct	Kfree (mem_devp );
Release Device number	Unregister_chrdev_region