private_data改进
为设备驱动支持多个设备个体做准备，针对private_data进行改进
在设备打开操作中通过inode中保存的i_cdev获取代表当前设备的cdev对象
通过代表当前设备的cdev对象得到包含该对象的设备私有数据结构体
将设备私有数据结构体指针保存到struct file的private_data成员中

在其它设备操作中直接使用保存在struct file的private_date成员中的当前设备私有数据结构体

//Copyright (c) 2013.TianYuan

//All rights reserved.

//

//文件名称: char_device_driver06.c

//文件标识: 支持多设备:创建10个设备节点文件,通过cdd_cdev结构中的led变量区分是哪个节点

//#测试： cat /dev/cdd0

//当前版本：1.0

//作者：wuyq 

//

//取代版本：xxx

//原作者：xxx

//完成日期：2013-11-28

#include "linux/init.h"

#include "linux/module.h"

#include "linux/fs.h"

#include "linux/cdev.h"

#include "linux/device.h"

#include "linux/slab.h"

MODULE_LICENSE("GPL");

#define CDD_MAJOR 200//cat /proc/devices找一个尚未使用的

#define CDD_MINOR 0

#define CDD_COUNT 10

dev_t dev = 0;

u32 cdd_major = 0;

u32 cdd_minor = 0;

struct class *dev_class = NULL;

struct cdd_cdev{

struct cdev cdev;

struct device *dev_device;

u8 led;

};

struct cdd_cdev *cdd_cdevp = NULL;

int cdd_open(struct inode* inode, struct file *filp)

{

struct cdd_cdev *pcdevp = NULL;

printk("enter cdd_open!\n");

 

pcdevp = container_of(inode->i_cdev, struct cdd_cdev, cdev);

printk("led = %d\n", pcdevp->led);

 

filp->private_data = pcdevp;

 

return 0;

}

int cdd_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)

{

struct cdd_cdev *cdevp = filp->private_data;

printk("enter cdd_read!\n");

printk("led = %d\n", cdevp->led);

return 0;

}

int cdd_write(struct file *filp, const char __user *buf, size_t count, loff_t *offset)

{

struct cdd_cdev *cdevp = filp->private_data;

printk("enter cdd_write!\n");

printk("led = %d\n", cdevp->led);

return 0;

}

int cdd_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long data)

{

printk("enter cdd_ioctl!\n");

return 0;

}

int cdd_release(struct inode *inode, struct file *filp)

{

printk("enter cdd_release!\n");

return 0;

}

struct file_operations cdd_fops = {

.owner = THIS_MODULE,

.open = cdd_open,

.read = cdd_read,

.write = cdd_write,

.ioctl = cdd_ioctl,

.release = cdd_release,

};

int __init cdd_init(void)

{

int ret = 0;

int i = 0;

 

if(cdd_major){

dev = MKDEV(CDD_MAJOR, CDD_MINOR);//生成设备号

//注册设备号;1、要注册的起始设备号2、连续注册的设备号个数3、名字

ret = register_chrdev_region(dev, CDD_COUNT, "cdd_demo");

}else{

// 动态分配设备号

ret = alloc_chrdev_region(&dev, cdd_minor, CDD_COUNT, "cdd_demo02");

}

 

if(ret < 0){

printk("register_chrdev_region failed!\n");

goto failure_register_chrdev;

}

//获取主设备号

cdd_major = MAJOR(dev);

printk("cdd_major = %d\n", cdd_major);

 

cdd_cdevp = kzalloc(sizeof(struct cdd_cdev)*CDD_COUNT, GFP_KERNEL);

if(IS_ERR(cdd_cdevp)){

printk("kzalloc failed!\n");

goto failure_kzalloc;

}

//创建设备类

dev_class = class_create(THIS_MODULE, "cdd_class");

if(IS_ERR(dev_class)){

printk("class_create failed!\n");

goto failure_dev_class;

}

for(i=0; i

//初始化cdev

cdev_init(&(cdd_cdevp[i].cdev), &cdd_fops);

//添加cdev到内核

cdev_add(&(cdd_cdevp[i].cdev), dev+i, 1);

// “/dev/xxx” 

device_create(dev_class, NULL, dev+i, NULL, "cdd%d", i);

 

cdd_cdevp[i].led = i;//为led变量赋值，通过led区分是一组设备中的哪个设备

 

}

 

return 0;

failure_dev_class:

kfree(cdd_cdevp);

failure_kzalloc:

unregister_chrdev_region(dev, CDD_COUNT);

failure_register_chrdev:

return ret;

}

void __exit cdd_exit(void)

{

//逆序消除

int i = 0;

for(; i < CDD_COUNT; i++){

device_destroy(dev_class, dev+i);

cdev_del(&(cdd_cdevp[i].cdev));

//cdev_del(&((cdd_cdevp+i)->cdev));

}

class_destroy(dev_class);

kfree(cdd_cdevp);

unregister_chrdev_region(dev, CDD_COUNT);

}

module_init(cdd_init);

module_exit(cdd_exit);