------------------------------------------------------------------------------------------------------------------------------
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
------------------------------------------------------------------------------------------------------------------------------
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[]; BYTE ds18b20_reset(void)
{
s3c2410_gpio_cfgpin(S3C2410_GPG(), S3C2410_GPIO_OUTPUT); //配置GP0输出模式
s3c2410_gpio_setpin(S3C2410_GPG(), LOW); //向ds18b20发送一个下降沿，并保持480us
udelay();
s3c2410_gpio_setpin(S3C2410_GPG(), HIGH); //向ds18b20发送一个上升沿，此时可释放ds18b20总线
udelay(); //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(), 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()))
{
printk("ds18b20 reset failed.\r\n");
return ;
}
udelay();
return ;
} BYTE ds18b20_read_byte(void)
{
BYTE i = ;
BYTE byte = ;
// 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 = ; i < ; i++)
{
s3c2410_gpio_cfgpin(S3C2410_GPG(), S3C2410_GPIO_OUTPUT); s3c2410_gpio_setpin(S3C2410_GPG(), LOW);
udelay();
byte >>= ;
s3c2410_gpio_setpin(S3C2410_GPG(), HIGH);
s3c2410_gpio_cfgpin(S3C2410_GPG(), 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()))
byte |= 0x80;
udelay();
}
return byte;
} BYTE ds18b20_write_byte(BYTE byte)
{
BYTE i;
s3c2410_gpio_cfgpin(S3C2410_GPG(), 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 = ; i < ; i++)
{
s3c2410_gpio_setpin(S3C2410_GPG(), LOW);
udelay();
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(), 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(), LOW);
}
// 电平状态保持60微秒
udelay(); s3c2410_gpio_setpin(S3C2410_GPG(), HIGH); //释放总线
udelay();
byte >>= ;
}
s3c2410_gpio_setpin(S3C2410_GPG(), 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();
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(); while(ds18b20_reset()); //循环判断DS18B20直到复位，延时200 ms;
udelay();
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[] = ds18b20_read_byte(); //读温度整数部分;
data[] = 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[] = data[];
buff[] = data[]; return ;
} 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.\n"); 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 = ;
int debug = DISABLE; static struct cdev *ds18b20_cdev; typedef unsigned char BYTE;
static BYTE data[]; BYTE ds18b20_reset(void)
{
s3c2410_gpio_cfgpin(S3C2410_GPG(), S3C2410_GPIO_OUTPUT);
s3c2410_gpio_setpin(S3C2410_GPG(), LOW);
udelay();
s3c2410_gpio_setpin(S3C2410_GPG(), HIGH);
udelay(); s3c2410_gpio_cfgpin(S3C2410_GPG(), S3C2410_GPIO_INPUT);
if(s3c2410_gpio_getpin(S3C2410_GPG()))
{
printk("ds18b20 reset failed.\r\n");
return ;
}
udelay();
return ;
} BYTE ds18b20_read_byte(void)
{
BYTE i = ;
BYTE byte = ; for(i = ; i < ; i++)
{
s3c2410_gpio_cfgpin(S3C2410_GPG(), S3C2410_GPIO_OUTPUT);
s3c2410_gpio_setpin(S3C2410_GPG(), LOW);
udelay();
byte >>= ;
s3c2410_gpio_setpin(S3C2410_GPG(), HIGH);
s3c2410_gpio_cfgpin(S3C2410_GPG(), S3C2410_GPIO_INPUT);
if(s3c2410_gpio_getpin(S3C2410_GPG()))
byte |= 0x80;
udelay();
}
return byte;
} BYTE ds18b20_write_byte(BYTE byte)
{
BYTE i;
s3c2410_gpio_cfgpin(S3C2410_GPG(), S3C2410_GPIO_OUTPUT);
for(i = ; i < ; i++)
{
s3c2410_gpio_setpin(S3C2410_GPG(), LOW);
udelay();
if(byte & HIGH)
{
s3c2410_gpio_setpin(S3C2410_GPG(), HIGH);
}
else
{
s3c2410_gpio_setpin(S3C2410_GPG(), LOW);
}
udelay(); s3c2410_gpio_setpin(S3C2410_GPG(), HIGH);
udelay();
byte >>= ;
}
s3c2410_gpio_setpin(S3C2410_GPG(), HIGH);
return ;
} void ds18b20_proc(void)
{
while(ds18b20_reset());
udelay();
ds18b20_write_byte(0xcc);
ds18b20_write_byte(0x44);
udelay(); while(ds18b20_reset());
udelay();
ds18b20_write_byte(0xcc);
ds18b20_write_byte(0xbe); data[] = ds18b20_read_byte();
data[] = ds18b20_read_byte();
} static ssize_t s3c2440_ds18b20_read(struct file *filp, char *buff, size_t len, loff_t *off)
{
ds18b20_proc(); buff[] = data[];
buff[] = data[]; return ;
} 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( != ds18b20_reset())
{
printk(KERN_ERR "s3c2440 ds18b20 hardware initialize failure.\n");
return -ENODEV;
} if( != dev_major)
{
devno = MKDEV(dev_major, );
result = register_chrdev_region(devno, , DEV_NAME);
}
else
{
result = alloc_chrdev_region(&devno, dev_minor, , DEV_NAME);
dev_major = MAJOR(devno);
} if(result < )
{
printk(KERN_ERR "s3c %s driver cannot use major %d.\n", DEV_NAME, dev_major);
return -ENODEV;
}
printk(KERN_DEBUG "s3c %s driver use major %d.\n", DEV_NAME, dev_major); if(NULL == (ds18b20_cdev = cdev_alloc()))
{
printk(KERN_ERR "s3c %s driver cannot register cdev: result = %d.\n", DEV_NAME, result);
unregister_chrdev_region(devno, );
return -ENOMEM;
} ds18b20_cdev -> owner = THIS_MODULE;
cdev_init(ds18b20_cdev, &ds18b20_fops); result = cdev_add(ds18b20_cdev, devno, );
if( != result)
{
printk(KERN_ERR "s3c %s driver cannot register cdev: result = %d.\n", DEV_NAME, result);
goto ERROR;
} printk(KERN_ERR "s3c %s driver[major=%d] Version %d.%d.%d installed successfully.\n",DEV_NAME, dev_major, DRV_MAJOR_VER, DRV_MINOR_VER, DRV_REVER_VER);
return ; ERROR:
printk(KERN_ERR "s3c %s driver installed failure./", DEV_NAME);
cdev_del(ds18b20_cdev);
unregister_chrdev_region(devno, );
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, ); printk(KERN_ERR "s3c %s driver version %d.%d.%d removed!\n", 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 = ;
unsigned char buff[];
unsigned short temp = ;
int flag = ; if ((fd=open("/dev/ds18b20",O_RDWR | O_NDELAY | O_NOCTTY)) < )
{
perror("open device ds18b20 failed.\r\n");
exit();
}
while()
{
printf("open device ds18b20 success.\r\n");
read(fd, buff, sizeof(buff));
temp=((unsigned short)buff[])<<;
temp|=(unsigned short)buff[];
result=0.0625*((double)temp);
printf("temperature is %4f \r\n", result);
sleep();
}
close(fd); return ;
} /* ----- End of main() ----- */