2023.2.16 作业

Linux内核驱动程序：IIC接口控制SI7006温湿度传感器

最新推荐文章于 2025-11-30 14:17:11 发布

原创最新推荐文章于 2025-11-30 14:17:11 发布 · 185 阅读

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CC 4.0 BY-SA版权

文章标签：

#linux #驱动开发

该文章展示了如何编写Linux内核驱动程序，用于通过IIC接口与SI7006温湿度传感器通信。驱动代码包括了设备的打开、关闭、ioctl操作以及读取传感器数据的函数。测试文件演示了如何通过ioctl调用从驱动中获取温湿度数据。

IIC设备驱动，控制si7006测量温湿度

驱动文件：

#include <linux/init.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include <linux/of_irq.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/i2c.h>
#include <linux/module.h>

#define GET_HUM     _IOR('s',0,int)
#define GET_TEMP    _IOR('s',1,int)

int si7006_open(struct inode *, struct file *);
long si7006_ioctl(struct file *, unsigned int, unsigned long);
int si7006_close(struct inode *, struct file *);
int si7006_up(void);
void si7006_del(void);

struct dev_struct {
    int major;
    int minor;
    int count;
    dev_t devno;
    char *name;
    struct class *cls;
    struct device *dev;
    struct cdev *cdev;
    struct file_operations fops;
};

struct dev_struct si7006 = {
    .major=0,
    .minor=0,
    .count=1,
    .name="si7006",
    .fops={
        .open=si7006_open,
        .unlocked_ioctl=si7006_ioctl,
        .release=si7006_close,
    },
};

struct i2c_client *cli;

unsigned int i2c_read_hum(unsigned char reg)
{
    int ret;
    unsigned short hum;
    struct i2c_msg r_msg[] = {
        [0] = {
            .addr = cli->addr,
            .flags = 0,
            .len = 1,
            .buf=(char *)&reg,
        },
        [1]={
            .addr=cli->addr,
            .flags=1,
            .len=2,
            .buf=(char *)&hum,
        },
    };
    ret = i2c_transfer(cli->adapter, r_msg, ARRAY_SIZE(r_msg));
    if(ret!=ARRAY_SIZE(r_msg)){
        printk("消息发送失败\n");
        return -EINVAL;
    }
    hum = hum >> 8 | hum << 8;
    return hum;
}

int i2c_read_temp(unsigned char reg)
{
    int ret;
    short temp;
    struct i2c_msg r_msg[] = {
        [0] = {
            .addr = cli->addr,
            .flags = 0,
            .len = 1,
            .buf=(char *)&reg,
        },
        [1]={
            .addr=cli->addr,
            .flags=1,
            .len=2,
            .buf=(char *)&temp,
        },
    };
    ret = i2c_transfer(cli->adapter, r_msg, ARRAY_SIZE(r_msg));
    if(ret!=ARRAY_SIZE(r_msg)){
        printk("消息发送失败\n");
        return -EINVAL;
    }
    temp = temp >> 8 | temp << 8;
    return temp;
}

int si7006_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
    int ret;
    cli = client;
    ret = si7006_up(); // 创建字符设备驱动
    if(ret<0){
        goto out1;
    }
    return 0;
out1:
    return ret;
}

int si7006_remove(struct i2c_client *client)
{
    si7006_del();
    return 0;
}

struct of_device_id of_match[] = {
    {.compatible="hqyj,si7006"},
    {}
};

struct i2c_driver i2c_si7006 = {
    .probe=si7006_probe,
    .remove=si7006_remove,
    .driver={
        .name="si7006",
        .of_match_table=of_match,
    },
};

module_i2c_driver(i2c_si7006);  //一键注册宏
MODULE_DEVICE_TABLE(of,of_match); //热插拔
MODULE_LICENSE("GPL");

/**********************************************************************/
int si7006_up(void)
{
    int ret;
    int i;
    // 申请字符设备
    si7006.cdev=cdev_alloc();
    if(si7006.cdev==NULL){
        printk("字符设备申请失败\n");
        ret = -ENOMEM;
        goto ERR1;
    }

    //初始化字符设备
    cdev_init(si7006.cdev,&si7006.fops);

    // 申请设备号
    if(si7006.major==0){
        ret = alloc_chrdev_region(&si7006.devno,si7006.minor,si7006.count,si7006.name);
        if(ret<0){
            printk("申请设备号失败\n");
            goto ERR2;
        }
        si7006.major = MAJOR(si7006.devno);
    }else if(si7006.major>0){
        ret = register_chrdev_region(MKDEV(si7006.major,si7006.minor),si7006.count,si7006.name);
        if(ret<0){
            printk("申请设备号失败\n");
            goto ERR2;
        }
        si7006.devno = MKDEV(si7006.major, si7006.minor);
    }

    //向内核注册字符设备
    ret=cdev_add(si7006.cdev,si7006.devno,si7006.count);
    if(ret<0){
        printk("注册字符设备失败\n");
        goto ERR3;
    }

    //自动创建设备节点
    //向上层提交目录
    si7006.cls=class_create(THIS_MODULE,si7006.name);
    if(IS_ERR(si7006.cls)){
        printk("向上层提交目录失败\n");
        ret = PTR_ERR(si7006.cls);
        goto ERR4;
    }

    //向上层提交节点信息
    if(si7006.count>1){
        for (i = si7006.minor; i < si7006.minor+si7006.count;i++){
            si7006.dev = device_create(si7006.cls, NULL, MKDEV(si7006.major,i), NULL,\
                                        "%s%d", si7006.name, i);
            if(IS_ERR(si7006.dev)){
                printk("向上层提交节点信息失败\n");
                ret = PTR_ERR(si7006.dev);
                goto ERR6;
            }
        }
    }else{
        si7006.dev = device_create(si7006.cls, NULL, si7006.devno, NULL,"%s", si7006.name);
        if(IS_ERR(si7006.dev)){
                printk("向上层提交节点信息失败\n");
                ret = PTR_ERR(si7006.dev);
                goto ERR5;
        }
    }

    return 0;
ERR6:
    for (i--; i >= si7006.major;i--){
        device_destroy(si7006.cls,MKDEV(si7006.major,i));
    }
ERR5:
    class_destroy(si7006.cls);
ERR4:
    cdev_del(si7006.cdev);
ERR3:
    unregister_chrdev_region(si7006.devno,si7006.count);
ERR2:
    kfree(si7006.cdev);
ERR1:
    return ret;
}

void si7006_del(void)
{
    int i;
    if(si7006.count>1){
        for (i = si7006.minor; i < si7006.minor+si7006.count;i++){
            device_destroy(si7006.cls,MKDEV(si7006.major,i));
        }
    }else{
        device_destroy(si7006.cls,si7006.devno);
    }
    class_destroy(si7006.cls);
    cdev_del(si7006.cdev);
    unregister_chrdev_region(si7006.devno,si7006.count);
    kfree(si7006.cdev);
}

int si7006_open(struct inode *inode, struct file *file)
{
    return 0;
}

long si7006_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 
{
    int ret;
    unsigned int hum;
    int temp;
    switch (cmd){
        case GET_HUM:
            hum = i2c_read_hum(0xE5);
            ret = copy_to_user((void *)arg,&hum,_IOC_SIZE(cmd));
            if(ret){
                printk("数据拷贝失败\n");
                return -EINVAL;
            }
            break;
        case GET_TEMP:
            temp = i2c_read_temp(0xE3);
            ret = copy_to_user((void *)arg,&temp,_IOC_SIZE(cmd));
            if(ret){
                printk("数据拷贝失败\n");
                return -EINVAL;
            }
            break;
    }
    return 0;
}

int si7006_close(struct inode *inode, struct file *file)
{
    return 0;
}

测试文件：

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/epoll.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>

#define GET_HUM     _IOR('s',0,int)
#define GET_TEMP    _IOR('s',1,int)

#define PRINT_ERR(msg) \
    do                 \
    {                  \
        perror(msg);   \
        return -1;     \
    } while (0)

int main(int argc,const char * argv[])
{
    int temp_data;
    unsigned int hum_data;
    float temp, hum;
    int fd = open("/dev/si7006", O_RDWR);
    if(fd<0){
        PRINT_ERR("open error");
        exit(-1);
    }
    while(1){
        ioctl(fd,GET_HUM,&hum_data);
        ioctl(fd, GET_TEMP, &temp_data);
        hum = 125.0 * hum_data / 65536 - 6;
        temp = 175.72 * temp_data / 65536 - 46.85;
        printf("hum=%.2f,temp=%.2f\n", hum, temp);
        sleep(1);
    }
    return 0;
}