驱动开发11-1 编写IIC驱动-读取温湿度数据

头文件 head.h

#ifndef __HEAD_H__
#define __HEAD_H__
#define GET_HUM _IOR('m', 1, int)
#define GET_TEM _IOR('m', 0, int)
#endif

应用程序 si7006.c

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <arpa/inet.h>
#include "head.h"int main(int argc, char const *argv[])
{char buf[128]={0};unsigned short hum,tem;float hum1,tem1;int fd = open("/dev/si7006",O_RDWR);if(fd < 0){printf("打开设备文件失败\n");exit(-1);}while(1){//读取温湿度数据ioctl(fd,GET_HUM,&hum);ioctl(fd,GET_TEM,&tem);//进行字节序转换hum = ntohs(hum);tem = ntohs(tem);//数据转换hum1 = (float)hum*125/65536-6;tem1 = (float)tem*175.72/65536-46.85;printf("hum = %f    tem = %f\n",hum1,tem1);sleep(1);}close(fd);return 0;
}

驱动程序 iic.c

#include <linux/init.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/fs.h>
#include <linux/device.h>
#include "head.h"struct i2c_client *client1;
unsigned int major;
struct class *cls;
struct device *dev;
//封装读取温湿度数据的函数
short read_hum_tem_value(char reg)
{short value; //保存读到的温湿度数据char r_buf[] = {reg};//消息结构体的封装struct i2c_msg r_msg[] = {[0] = {.addr = client1->addr,.flags = 0,.len = sizeof(r_buf),.buf = r_buf,},[1] = {.addr =client1->addr,.flags = 1,.len = 2,.buf = (char *)&value,},};//发送消息int ret = i2c_transfer(client1->adapter,r_msg,2);if(ret != 2){printk("消息传输失败\n");return -1;}return value;
}
int mycdev_open(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;
}
long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{short hum,tem;int ret;switch ((cmd)){case GET_HUM:hum = read_hum_tem_value(0xE5);ret = copy_to_user((void *)arg,&hum,2);if(ret){printk("coyp_to_user err %d\n",__LINE__);}break;case GET_TEM:tem = read_hum_tem_value(0xE5);ret = copy_to_user((void *)arg,&tem,2);if(ret){printk("coyp_to_user err %d\n",__LINE__);}break;}return 0;
}
int mycdev_close(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;
}
//定义操作方法结构体变量并复制
struct file_operations fops = {.open = mycdev_open,.unlocked_ioctl = mycdev_ioctl,.release = mycdev_close,
};
//给对象分配空间并且初始化
int i2c_probe(struct i2c_client *client, const struct i2c_device_id *id)
{client1 = client;int ret;//float hum1,tem1;printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);//字符设备驱动的注册major = register_chrdev(0,"si7006",&fops);if(major < 0){printk("字符设备驱动注册失败\n");ret = major;goto out1;}printk("字符设备驱动注册成功\n");//向上提交目录cls = class_create(THIS_MODULE,"si7006");if(IS_ERR(cls)){printk("向上提交目录失败\n");ret = -PTR_ERR(cls);goto out2;}printk("向上提交目录成功\n");//向上提交设备节点信息dev = device_create(cls,NULL,MKDEV(major,0),NULL,"si7006");if(IS_ERR(dev)){printk("向上提交设备节点失败\n");ret = -PTR_ERR(dev);goto out3;}printk("向上提交设备节点成功\n");return 0;
out3:class_destroy(cls);
out2:unregister_chrdev(major,"si7006");
out1:return ret;
}
int i2c_remove(struct i2c_client *client)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);//设备信息的注销device_destroy(cls,MKDEV(major,0));//设备节点的销毁class_destroy(cls);//驱动的注销unregister_chrdev(major,"si7006");return 0;
}
//定义设备树匹配的表
struct of_device_id oftable[]={{.compatible="hqyj,si7006",},{},
};
struct i2c_driver i2c_drv={.probe=i2c_probe,.remove=i2c_remove,.driver={.name="si7006",.of_match_table=oftable,},
};
module_i2c_driver(i2c_drv);
MODULE_LICENSE("GPL");

效果演示