Linux驱动开发之字符设备模板

/*****************************
*
* 驱动程序模板
* 版本：V1
* 使用方法(末行模式下)：
* :%s/xxx/"你的驱动名称"/g
*
*******************************/

#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/mman.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/raw.h>
#include <linux/tty.h>
#include <linux/capability.h>
#include <linux/ptrace.h>
#include <linux/device.h>
#include <linux/highmem.h>
#include <linux/crash_dump.h>
#include <linux/backing-dev.h>
#include <linux/bootmem.h>
#include <linux/splice.h>
#include <linux/pfn.h>
#include <linux/export.h>
#include <linux/io.h>
#include <linux/aio.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/uaccess.h>
#include <linux/ioctl.h>

/**************** 基本定义 **********************/
//内核空间缓冲区定义
#if 0
#define KB_MAX_SIZE 20
#define kbuf[KB_MAX_SIZE];
#endif

//加密函数参数内容： _IOW(IOW_CHAR , IOW_NUMn , IOW_TYPE)
//加密函数用于xxx_ioctl函数中
//使用举例：ioctl(fd , _IOW(‘L‘,0x80,long) , 0x1);
//#define NUMn xxx , if you need!
#define IOW_CHAR ‘L‘
#define IOW_TYPE long
#define IOW_NUM1 0x80

//初始化函数必要资源定义
//用于初始化函数当中
//device number;
dev_t dev_num;
//struct dev
struct cdev xxx_cdev;
//auto "mknode /dev/xxx c dev_num minor_num"
struct class *xxx_class = NULL;
struct device *xxx_device = NULL;

/**************** 结构体 file_operations 成员函数 *****************/
//open
static int xxx_open(struct inode *inode, struct file *file)
{
printk("xxx drive open...\n");

return 0;
}

//close
static int xxx_close(struct inode *inode , struct file *file)
{
printk("xxx drive close...\n");

return 0;
}

//read
static ssize_t xxx_read(struct file *file, char __user *buffer,
size_t len, loff_t *pos)
{
int ret_v = 0;
printk("xxx drive read...\n");

return ret_v;
}

//write
static ssize_t xxx_write( struct file *file , const char __user *buffer,
size_t len , loff_t *offset )
{
int ret_v = 0;
printk("xxx drive write...\n");

return ret_v;
}

//unlocked_ioctl
static int xxx_ioctl (struct file *filp , unsigned int cmd , unsigned long arg)
{
int ret_v = 0;
printk("xxx drive ioctl...\n");

switch(cmd)
{
//常规：
//cmd值自行进行修改
case 0x1:
{
if(arg == 0x1) //第二条件；
{

}
}
break;

//带密码保护：
//请在"基本定义"进行必要的定义
case _IOW(IOW_CHAR,IOW_NUM1,IOW_TYPE):
{
if(arg == 0x1) //第二条件
{

}

}
break;

default:
break;
}

return ret_v;
}

/***************** 结构体： file_operations ************************/
//struct
static const struct file_operations xxx_fops = {
.owner = THIS_MODULE,
.open = xxx_open,
.release = xxx_close,
.read = xxx_read,
.write = xxx_write,
.unlocked_ioctl = xxx_ioctl,
};

/************* functions: init , exit*******************/
//条件值变量，用于指示资源是否正常使用
unsigned char init_flag = 0;
unsigned char add_code_flag = 0;

//init
static __init int xxx_init(void)
{
int ret_v = 0;
printk("xxx drive init...\n");

//函数alloc_chrdev_region主要参数说明：
//参数2： 次设备号
//参数3： 创建多少个设备
if( ( ret_v = alloc_chrdev_region(&dev_num,0,1,"xxx") ) < 0 )
{
goto dev_reg_error;
}
init_flag = 1; //标示设备创建成功；

printk("The drive info of xxx:\nmajor: %d\nminor: %d\n",
MAJOR(dev_num),MINOR(dev_num));

cdev_init(&xxx_cdev,&xxx_fops);
if( (ret_v = cdev_add(&xxx_cdev,dev_num,1)) != 0 )
{
goto cdev_add_error;
}

xxx_class = class_create(THIS_MODULE,"xxx");
if( IS_ERR(xxx_class) )
{
goto class_c_error;
}

xxx_device = device_create(xxx_class,NULL,dev_num,NULL,"xxx");
if( IS_ERR(xxx_device) )
{
goto device_c_error;
}
printk("auto mknod success!\n");

//------------ 请在此添加您的初始化程序 --------------//

//如果需要做错误处理，请：goto xxx_error;

add_code_flag = 1;
//---------------------- END ---------------------------//

goto init_success;

dev_reg_error:
printk("alloc_chrdev_region failed\n");
return ret_v;

cdev_add_error:
printk("cdev_add failed\n");
unregister_chrdev_region(dev_num, 1);
init_flag = 0;
return ret_v;

class_c_error:
printk("class_create failed\n");
cdev_del(&xxx_cdev);
unregister_chrdev_region(dev_num, 1);
init_flag = 0;
return PTR_ERR(xxx_class);

device_c_error:
printk("device_create failed\n");
cdev_del(&xxx_cdev);
unregister_chrdev_region(dev_num, 1);
class_destroy(xxx_class);
init_flag = 0;
return PTR_ERR(xxx_device);

//------------------ 请在此添加您的错误处理内容 ----------------//
xxx_error:

add_code_flag = 0;
return -1;
//-------------------- END -------------------//

init_success:
printk("xxx init success!\n");
return 0;
}

//exit
static __exit void xxx_exit(void)
{
printk("xxx drive exit...\n");

if(add_code_flag == 1)
{
//---------- 请在这里释放您的程序占有的资源 ---------//
printk("free your resources...\n");

printk("free finish\n");
//---------------------- END -------------------//
}

if(init_flag == 1)
{
//释放初始化使用到的资源;
cdev_del(&xxx_cdev);
unregister_chrdev_region(dev_num, 1);
device_unregister(xxx_device);
class_destroy(xxx_class);
}
}

/**************** module operations**********************/
//module loading
module_init(xxx_init);
module_exit(xxx_exit);

//some infomation
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("from Jafy");
MODULE_DESCRIPTION("xxx drive");

/********************* The End ***************************/