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<CDD_COUNT; 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);