[系统运维]iic 驱动框架（在iic驱动框架下的字符设备驱动框架）

首先修改设备树，添加ap3216c@1e? 节点信息，ap3216c 是支持iic协议的芯片

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/ide.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of_gpio.h>
#include <linux/semaphore.h>
#include <linux/timer.h>
#include <linux/i2c.h>
#include <asm/mach/map.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include "ap3216creg.h"

#define AP3216C_CNT 1
#define AP3216C_NAME "ap3216c"

struct ap3216c_dev{
?? ?dev_t devid; //设备号
?? ?struct cdev cdev; //字符设备
?? ?struct class *class; //类
?? ?struct device *device; //设备
?? ?struct device_node *nd; //设备节点
?? ?int major; //主设备号
?? ?int minor; //次设备号
?? ?void *private_data; //私有数据
?? ?
};

struct ap3216c_dev ap3216cdev;

static int ap3216c_open(struct inode *inode, struct file *filp)
{
?? ?filp->private_data = &ap3216cdev;
?? ?printk("ap3216c_open\r\n");

?? ?return 0;
}

static ssize_t ap3216c_read(struct file *filp, char __user *buf, size_t cnt, loff_t *off)
{
?? ?printk("ap3216c_read\r\n");
?? ?return 0;
}

static int ap3216c_release(struct inode *inode, struct file *filp)
{
?? ?printk("ap3216c_release\r\n");
?? ?return 0;
}

//ap3216c操作函数
static const struct file_operations ap3216c_ops = {
?? ?.owner = THIS_MODULE,
?? ?.open = ap3216c_open,
?? ?.read = ap3216c_read,
?? ?.release = ap3216c_release,?
};

static int ap3216c_probe(struct i2c_client *client,const struct i2c_device_id *id)
{
?? ?int ret = 0;
?? ?printk("ap3216c_probe\r\n");

?? ?//搭建字符设备驱动框架
?? ?//1.构建设备号
?? ?if(ap3216cdev.major){
?? ??? ?ap3216cdev.devid = MKDEV(ap3216cdev.major,0);
?? ??? ?register_chrdev_region(ap3216cdev.devid,AP3216C_CNT,AP3216C_NAME);
?? ?}else{
?? ??? ?alloc_chrdev_region(&ap3216cdev.devid, 0, AP3216C_CNT, AP3216C_NAME);
?? ??? ?ap3216cdev.major = MAJOR(ap3216cdev.devid);
?? ??? ?ap3216cdev.minor = MINOR(ap3216cdev.devid);
?? ?}

?? ?printk("major:%d\r\n",ap3216cdev.major);
?? ?printk("minor:%d\r\n",ap3216cdev.minor);
?? ?//2.注册设备
?? ?cdev_init(&ap3216cdev.cdev,&ap3216c_ops);
?? ?cdev_add(&ap3216cdev.cdev,ap3216cdev.devid,AP3216C_CNT);

?? ?//3.创建类
?? ?ap3216cdev.class = class_create(THIS_MODULE,AP3216C_NAME);
?? ?if(IS_ERR(ap3216cdev.class)){
?? ??? ?return PTR_ERR(ap3216cdev.class);
?? ?}

?? ?//4.创建设备
?? ?ap3216cdev.device = device_create(ap3216cdev.class,NULL,ap3216cdev.devid,NULL,AP3216C_NAME);
?? ?if(IS_ERR(ap3216cdev.device)){
?? ??? ?return PTR_ERR(ap3216cdev.device);
?? ?}

?? ?ap3216cdev.private_data = client;

?? ?return 0;
}

static int ap3216c_remove(struct i2c_client *client)
{
?? ?//删除设备
?? ?cdev_del(&ap3216cdev.cdev);
?? ?//删除设备号
?? ?unregister_chrdev_region(ap3216cdev.devid,AP3216C_CNT);
?? ?//注销类和设备
?? ?device_destroy(ap3216cdev.class,ap3216cdev.devid);
?? ?class_destroy(ap3216cdev.class);

?? ?return 0;
}

//传统匹配方式ID列表
static struct i2c_device_id ap3216c_id[] = {
?? ?{"alientek,ap3216c",0},
?? ?{}
};

//设备树匹配表
static struct of_device_id ap3216c_of_match[] = {
?? ?{.compatible = "alientek,ap3216c"},
?? ?{}
};

//i2c_driver
static struct i2c_driver ap3216c_driver = {

?? ?.probe = ap3216c_probe, //匹配成功调用此函数
?? ?.remove= ap3216c_remove,
?? ?.driver = {
?? ??? ?.name = "ap321c", //没有设备树时用名字和设备匹配
?? ??? ?.owner = THIS_MODULE,
?? ??? ?.of_match_table = ap3216c_of_match, //匹配表，有设备树时用匹配表和设备树里面的节点进行配对
?? ?},
?? ?.id_table = ap3216c_id,

};

//驱动入口函数
static int __init ap3216c_init(void)
{
?? ?int ret = 0;

?? ?ret = i2c_add_driver(&ap3216c_driver); ?//向系统注册i2c

?? ?return ret;
}

//驱动出口函数
static void __exit ap3216c_exit(void)
{
?? ?i2c_del_driver(&ap3216c_driver);
}

module_init(ap3216c_init);
module_exit(ap3216c_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("DENG");