ds18b20驱动及应用程序

------------------------------------------------------------------------------------------------------------------------------

交叉编译器：arm-linux-gcc-4.5.4

Linux内核版本：Linux-3.0

主机操作系统：Centos 6.5

开发板：FL2440

温度传感器:ds18b20

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之前看过led的，platform_led的，platform_button的。当时以为看懂了，可是真的拿到一个模块要去写他的驱动的时候发现有些无从下手。于是借鉴了朋友的一篇混杂设备驱动，半抄半写的写出来了一个miscdevice类型的驱动。之后又在miscdevice与led的基础上写出来了cdev类型的驱动。并附上一个小小的测试程序。

一、miscdevice驱动

#include <linux/interrupt.h>  
#include <linux/poll.h>  
#include <linux/configfs.h>  
#include <linux/module.h>  
#include <linux/kernel.h>  
#include <linux/fs.h>  
#include <linux/clk.h>  
#include <linux/init.h>  
#include <linux/device.h>  
#include <linux/miscdevice.h>  
#include <linux/delay.h>  
#include <linux/mm.h>  
#include <plat/regs-timer.h>  
#include <mach/regs-gpio.h>  
#include <mach/map.h>  
#include <mach/gpio-nrs.h>  
#include <mach/regs-irq.h>  
#include <asm/io.h>  
#include <mach/hardware.h>  
#include <asm/uaccess.h>  
#include <asm/system.h>  
#include <mach/regs-clock.h>  
#include <asm/irq.h>  
#include <linux/types.h>  
#include <linux/moduleparam.h>  
#include <linux/slab.h>  
#include <linux/errno.h>  
#include <linux/ioctl.h>  
#include <linux/cdev.h>  
#include <linux/string.h>  
#include <linux/list.h>  
#include <linux/pci.h>  
#include <asm/atomic.h>  
#include <asm/unistd.h>  
#include <linux/miscdevice.h>  
#include <linux/gpio.h>  

/*********************************************************************************
 *      Copyright:  (C) 2016 2013dianxin_3
 *                  All rights reserved.
 *
 *       Filename:  ds18b20.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(08/07/2016)
 *         Author:  xiaohexiansheng <1392195453@qq.com>
 *      ChangeLog:  1, Release initial version on "08/07/2016 02:21:17 PM"
 *                 
 ********************************************************************************/
#define DRV_AUTHOR                          "xiaohexiansheng <wcchz@hotmail.com>"
#define DRV_DESC                            "s3c2440 ds18b20 driver"
#define DEVICE_NAME                         "ds18b20"

#define LOW                                 0
#define HIGH                                1
typedef unsigned char BYTE;  

static BYTE data[2];

BYTE ds18b20_reset(void)
{
    s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT);         //配置GP0输出模式
    s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);            //向ds18b20发送一个下降沿，并保持480us
    udelay(480);
    s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);            //向ds18b20发送一个上升沿，此时可释放ds18b20总线
    udelay(60);

//以上动作是给ds18b20一个复位脉冲，通过配置GPIO引脚为输入模式可检测ds18b20是否复位成功
    s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_INPUT);
//若总线在释放后为高电平，则复位失败
    if(s3c2410_gpio_getpin(S3C2410_GPG(0)))
    {
        printk("ds18b20 reset failed.
");
        return 1;
    }
    udelay(240);
    return 0;
}

BYTE ds18b20_read_byte(void)
{
    BYTE i = 0;
    BYTE byte = 0;
    // 读“1”时隙：   
    //     若总线状态保持在低电平状态1微秒到15微秒之间   
    //     然后跳变到高电平状态且保持在15微秒到60微秒之间   
    //      就认为从DS18B20读到一个“1”信号   
    //     理想情况: 1微秒的低电平然后跳变再保持60微秒的高电平   
    // 读“0”时隙：   
    //     若总线状态保持在低电平状态15微秒到30微秒之间   
    //     然后跳变到高电平状态且保持在15微秒到60微秒之间   
    //     就认为从DS18B20读到一个“0”信号   
    //     理想情况: 15微秒的低电平然后跳变再保持46微秒的高电平   
    for(i = 0; i < 8; i++)
    {
        s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT);        
    
        s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
        udelay(1);
        byte >>= 1;
        s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
        s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_INPUT);
        // 若总线在我们设它为低电平之后若1微秒之内变为高   
        // 则认为从DS18B20处收到一个“1”信号   
        // 因此把byte的D7为置“1”  
        if(s3c2410_gpio_getpin(S3C2410_GPG(0)))
            byte |= 0x80;
        udelay(50);
    }
    return byte;
}

BYTE ds18b20_write_byte(BYTE byte)
{
    BYTE i;
    s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT);            // 配置GPG0为输出模式
    // 写“1”时隙：   
    //     保持总线在低电平1微秒到15微秒之间   
    //     然后再保持总线在高电平15微秒到60微秒之间   
    //     理想状态: 1微秒的低电平然后跳变再保持60微秒的高电平     
    // 写“0”时隙：   
    //     保持总线在低电平15微秒到60微秒之间   
    //     然后再保持总线在高电平1微秒到15微秒之间   
    //     理想状态: 60微秒的低电平然后跳变再保持1微秒的高电平   
    for(i = 0; i < 8; i++)
    {
        s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
        udelay(15);
        if(byte & HIGH)
        {
            // 若byte变量的D0位是1，则需向总线上写“1”   
            // 根据写“1”时隙规则，电平在此处翻转为高
            s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
        }
        else
        {
            // 若byte变量的D0位是0，则需向总线上写“0”   
            // 根据写“0”时隙规则，电平在保持为低
            s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
        }
        // 电平状态保持60微秒
        udelay(45);

        s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);        //释放总线
        udelay(1);
        byte >>= 1;
    }
    s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);        //释放总线
}

void ds18b20_proc(void)                //读取温度
{
    while(ds18b20_reset());            //循环判断DS18B20直到复位，延时120ms;
    udelay(120);
    ds18b20_write_byte(0xcc);        //写入CCH命令，跳过读序列号过程;
    ds18b20_write_byte(0x44);        //写入44H命令，开始温度转换，延时5 ms;
    udelay(5);

    while(ds18b20_reset());            //循环判断DS18B20直到复位，延时200 ms;
    udelay(200);
    ds18b20_write_byte(0xcc);        //写入CCH命令，跳过读序列号过程;
    ds18b20_write_byte(0xbe);        //写入BEH命令，读取寄存器;

    data[0] = ds18b20_read_byte();            //读温度整数部分;
    data[1] = ds18b20_read_byte();            //读温度小数部分
}

static ssize_t s3c2440_ds18b20_read(struct file *filp, char *buff, size_t len, loff_t *off)
{
    ds18b20_proc();

    buff[0] = data[0];
    buff[1] = data[1];

    return 1;
}

static struct file_operations s3c2440_ds18b20_fops =
{
    .owner = THIS_MODULE,
    .read = s3c2440_ds18b20_read,
};

static struct miscdevice misc =
{
    .minor = MISC_DYNAMIC_MINOR,
    .name = DEVICE_NAME,
    .fops = &s3c2440_ds18b20_fops,
};

static int __init s3c2440_ds18b20_init(void)
{
    int result;
    result = misc_register(&misc);
    printk(DEVICE_NAME "initialized.
");
    
    while(ds18b20_reset());            
    return result;
}

static void __exit s3c2440_ds18b20_exit(void)
{
    misc_deregister(&misc);
}

module_init(s3c2440_ds18b20_init);
module_exit(s3c2440_ds18b20_exit);
MODULE_AUTHOR(DRV_AUTHOR);
MODULE_DESCRIPTION(DRV_DESC);
MODULE_LICENSE("GPL");

二、cdevdevice驱动

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/delay.h>
#include <asm/irq.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/kdev_t.h>
#include <asm/uaccess.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>

/*********************************************************************************
 *      Copyright:  (C) 2016 2013dianxin_3
 *                  All rights reserved.
 *
 *       Filename:  ds18b20.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(08/08/2016)
 *         Author:  xiaohexiansheng <1392195453@qq.com>
 *      ChangeLog:  1, Release initial version on "08/08/2016 03:44:48 PM"
 *                 
 ********************************************************************************/
#define DRV_AUTHOR                          "xiaohexiansheng <1392195453@qq.com>"
#define DRV_DESC                            "S3C2440 ds18b20 driver"

#define DEV_NAME                            "ds18b20"
#define DISABLE                             0
#define DRV_MAJOR_VER                       1
#define DRV_MINOR_VER                       0
#define DRV_REVER_VER                       0

#define LOW                                 0
#define HIGH                                1

#ifndef DEV_MAJOR
#define DEV_MAJOR                           0
#endif

int dev_major = DEV_MAJOR;
int dev_minor = 0;
int debug = DISABLE;

static struct cdev          *ds18b20_cdev;

typedef unsigned char BYTE;
static BYTE data[2];

BYTE ds18b20_reset(void)
{
    s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT);
    s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
    udelay(480);
    s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
    udelay(60);

    s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_INPUT);
    if(s3c2410_gpio_getpin(S3C2410_GPG(0)))
    {
        printk("ds18b20 reset failed.
");
        return 1;
    }
    udelay(240);
    return 0;
}

BYTE ds18b20_read_byte(void)
{
    BYTE i = 0;
    BYTE byte = 0;

    for(i = 0; i < 8; i++)
    {
        s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT);
        s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
        udelay(1);
        byte >>= 1;
        s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
        s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_INPUT);
        if(s3c2410_gpio_getpin(S3C2410_GPG(0)))
            byte |= 0x80;
        udelay(50);
    }
    return byte;
}

BYTE ds18b20_write_byte(BYTE byte)
{
    BYTE i;
    s3c2410_gpio_cfgpin(S3C2410_GPG(0), S3C2410_GPIO_OUTPUT);
    for(i = 0; i < 8; i++)
    {
        s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
        udelay(15);
        if(byte & HIGH)
        {
            s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
        }
        else
        {
            s3c2410_gpio_setpin(S3C2410_GPG(0), LOW);
        }
        udelay(45);

        s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
        udelay(1);
        byte >>= 1;
    }
    s3c2410_gpio_setpin(S3C2410_GPG(0), HIGH);
    return 0;
}

void ds18b20_proc(void)
{
        while(ds18b20_reset());
        udelay(120);
        ds18b20_write_byte(0xcc);
        ds18b20_write_byte(0x44);
        udelay(5);

        while(ds18b20_reset());
        udelay(200);
        ds18b20_write_byte(0xcc);
        ds18b20_write_byte(0xbe);
          
        data[0] = ds18b20_read_byte();
        data[1] = ds18b20_read_byte();
}

static ssize_t s3c2440_ds18b20_read(struct file *filp, char *buff, size_t len, loff_t *off)
{
        ds18b20_proc();

        buff[0] = data[0];
        buff[1] = data[1];

        return 1;
}

static struct file_operations ds18b20_fops =
{

    .owner = THIS_MODULE,
    .read = s3c2440_ds18b20_read,
};

static int __init s3c_ds18b20_init(void)
{
    int                     result;
    dev_t                   devno;

    if(0 != ds18b20_reset())
    {
        printk(KERN_ERR "s3c2440 ds18b20 hardware initialize failure.
");
        return -ENODEV;
    }

    if(0 != dev_major)
    {
        devno = MKDEV(dev_major, 0);
        result = register_chrdev_region(devno, 1, DEV_NAME);
    }
    else
    {
        result = alloc_chrdev_region(&devno, dev_minor, 1, DEV_NAME);
        dev_major = MAJOR(devno);
    }

    if(result < 0)
    {
        printk(KERN_ERR "s3c %s driver cannot use major %d.
", DEV_NAME, dev_major);
        return -ENODEV;
    }
    printk(KERN_DEBUG "s3c %s driver use major %d.
", DEV_NAME, dev_major);

    if(NULL == (ds18b20_cdev = cdev_alloc()))
    {
        printk(KERN_ERR "s3c %s driver cannot register cdev: result = %d.
", DEV_NAME, result);
        unregister_chrdev_region(devno, 1);
        return -ENOMEM;
    }

    ds18b20_cdev -> owner = THIS_MODULE;
    cdev_init(ds18b20_cdev, &ds18b20_fops);

    result = cdev_add(ds18b20_cdev, devno, 1);
    if(0 != result)
    {
        printk(KERN_ERR "s3c %s driver cannot register cdev: result = %d.
", DEV_NAME, result);
        goto ERROR;
    }

    printk(KERN_ERR "s3c %s driver[major=%d] Version %d.%d.%d installed successfully.
",DEV_NAME, dev_major, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);
    return 0;

ERROR:
    printk(KERN_ERR "s3c %s driver installed failure./", DEV_NAME);
    cdev_del(ds18b20_cdev);
    unregister_chrdev_region(devno, 1);
    return result;
}

static void __exit s3c_ds18b20_exit(void)
{
    dev_t devno = MKDEV(dev_major, dev_minor);

    cdev_del(ds18b20_cdev);
    unregister_chrdev_region(devno, 1);

    printk(KERN_ERR "s3c %s driver version %d.%d.%d removed!
", DEV_NAME, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);
    return;
}

module_init(s3c_ds18b20_init);
module_exit(s3c_ds18b20_exit);

module_param(debug, int, S_IRUGO);
module_param(dev_major, int ,S_IRUGO);

MODULE_AUTHOR(DRV_AUTHOR);
MODULE_DESCRIPTION(DRV_DESC);
MODULE_LICENSE("GPL");

注：cdev的驱动需要手动创建设备节点，而misc不需要

三、测试程序

/*********************************************************************************
 *      Copyright:  (C) 2016 2013dianxin_3
 *                  All rights reserved.
 *
 *       Filename:  dsapp.c
 *    Description:  This file 
 *                 
 *        Version:  1.0.0(08/08/2016)
 *         Author:  xiaohexiansheng <1392195453@qq.com>
 *      ChangeLog:  1, Release initial version on "08/08/2016 10:19:25 AM"
 *                 
 ********************************************************************************/
#include <stdio.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <stdlib.h>
#include <termios.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/time.h>

/********************************************************************************
 *  Description:
 *   Input Args:
 *  Output Args:
 * Return Value:
 ********************************************************************************/
int main (int argc, char **argv)
{
    int fd;
    double result = 0;
    unsigned char buff[2];
    unsigned short temp = 0;
    int flag = 0;

    if ((fd=open("/dev/ds18b20",O_RDWR | O_NDELAY | O_NOCTTY)) < 0)
    {
        perror("open device ds18b20 failed.
");
        exit(1);
    }
    while(1)
    {
        printf("open device ds18b20 success.
");
        read(fd, buff, sizeof(buff));
        temp=((unsigned short)buff[1])<<8;
        temp|=(unsigned short)buff[0];
        result=0.0625*((double)temp);
        printf("temperature is %4f 
", result);
        sleep(2);
    }
    close(fd);

    return 0;
} /* ----- End of main() ----- */