一、编程要求

• 在内[[核中不支持浮点类型打印
• 将si7006硬件数据读取到内核空间，拷贝到用户空间
• 在i2c子系统驱动中，需要编写读取温湿度传感器函数
• 在probe函数中
  • 注册字符设备驱动(分步注册)
  • 自动创建设备节点
• 通过ioctl函数判断应用层发送命令码，是读取温度的数据还是湿度的数据
• 编写应用层程序 公式

#include <linux/init.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/fs.h>
#include <linux/device.h>struct i2c_client *gclient;
unsigned int major = 0;
#define CNAME "myled"
struct class *cls;
struct device *device;int myled_open(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;
}ssize_t myled_read(struct file *file, char __user *ubuf, size_t size, loff_t *loff)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0; 
}ssize_t myled_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;     
}int myled_close(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;     
}//操作方法结构体
const struct file_operations fops = {.open = myled_open,.read = myled_read,.write = myled_write,.release = myled_close,};//函数功能：读取电子串号和固件版本号的函数
int read_serial_firmware(unsigned short reg)
{char r_buf[] = {(reg >> 8 & 0xff),reg & 0xff};char value;int num;struct i2c_msg r_msg[2] = {[0] = {.addr = gclient->addr,  //从机地址.flags = 0, //写标志位.len = 2,  //消息长度.buf = r_buf,  //从reg寄存器中读取数据          },[1] = {.addr = gclient->addr,  //从机地址.flags = 1,//读标志位.len = 1,  //消息长度.buf = &value,  //读取到的数据内容            },};//发送数据num = i2c_transfer(gclient->adapter,r_msg,ARRAY_SIZE(r_msg));if(num != ARRAY_SIZE(r_msg)){printk("i2c transfer is error\n");return -EIO;}return value;
}//当设备驱动层和总线驱动层匹配成功执行probe函数
int si7006_probe(struct i2c_client *client, const struct i2c_device_id *id)
{int ret;gclient = client;printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);//读取电子串号ret = read_serial_firmware(0xFCC9);printk("serial(0x06) = %#x\n",ret);//读取固件版本号ret = read_serial_firmware(0x84B8);printk("fireware(0xff/0x20) = %#x\n",ret);//读取温湿度传感器协议版本号ret = read_serial_firmware(0xE340);printk("temperature(0xff/0x20)  = %#x\n",ret);ret = read_serial_firmware(0xE540);printk("Relative Humidity(0xff/0x20) = %#x\n",ret);//注册字符设备驱动major = register_chrdev(0,CNAME,&fops);if(major < 0){printk("register chrdev is error\n");return -EIO;}//向上层提交目录信息cls = class_create(THIS_MODULE,CNAME);if(IS_ERR(cls)){return PTR_ERR(cls);}//向上层提交设备节点信息device = device_create(cls,NULL,MKDEV(major,0),NULL,CNAME);if(IS_ERR(device)){return PTR_ERR(device);}printk("major = %d\n",major);//打印主设备号的值//判断读取的是温度还是湿度的数据，此处不会if(gclient->flags==1 && gclient->flags){;}return 0;
}//当任意一方卸载，执行remove函数
int si7006_remove(struct i2c_client *client)
{//注销字符设备驱动unregister_chrdev(major,CNAME);printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);return 0;
}const struct of_device_id si7006_tabble[] = {{.compatible = "hqyj,si7006",},{},//防止数组越界
};//初始化i2c_driver结构体
struct  i2c_driver si7006 ={.probe = si7006_probe,.remove = si7006_remove,.driver = {.name = "hello",.of_match_table = si7006_tabble,}
};module_i2c_driver(si7006);
MODULE_LICENSE("GPL");