基于Linux内核的1-wair总线驱动（…

最新推荐文章于 2024-02-21 18:01:37 发布

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本文详细解读了DS18B20温度传感器的驱动代码实现，包括初始化、配置、读取温度等功能，适用于嵌入式系统的应用。

********************************************************************************

驱动代码：ds18b20_drv

********************************************************************************

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

MODULE_LICENSE("GPL");

#define DS18B20_RESET (0x10009)
#define DS18B20_REL (0x10011)

#define SKIP_ROM    0xcc
#define COVERTT     0x44
#define READ_MEM    0xbe
#define WRITE_MEM   0x4e

#define NINE_BIT    0x1f
#define TEN_BIT     0x3f
#define ELE_BIT     0x5f
#define TWL_BIT     0x7f

#define TH 100
#define TL 0

#define TEMP_H 10000
#define TEMP_L -10000

static unsigned long *gpio_con;
static unsigned long *gpio_dat;

static void gpio_cfg_out(unsigned char val)
{
    *gpio_con &= ~0xf;
    *gpio_con |= 0x1;
    if (val == 0) {
        *gpio_dat &= ~0x1;
    } else {
        *gpio_dat |= 0x1;
    }
}

static unsigned char gpio_cfg_in(void)
{
*gpio_con &= ~0xf;
return *gpio_dat & 0x1;
}

static void ds18b20_write8(unsigned char data)
{
    int i = 0;
    for (; i<8; i++) {
        if ((data & 0x1) == 1) {
            gpio_cfg_out(0);
            udelay(3);
            gpio_cfg_out(1);
            udelay(80);
        } else {
            gpio_cfg_out(0);
            udelay(80);
            gpio_cfg_out(1);
            udelay(3);
        }
        data >>= 1;
    }
}

static unsigned char ds18b20_read8(void)
{
    int i = 0;
    unsigned char bit;
    unsigned char data = 0;

    for (; i<8; i++) {
        gpio_cfg_out(0);
        udelay(2);
        gpio_cfg_out(1);
        udelay(5);
        bit = gpio_cfg_in();
        data |= (bit << i);
        udelay(5);
        gpio_cfg_out(1);
        udelay(60);
    }
    return data;
}

static void ds18b20_reset(void)
{
unsigned char ret = 0;

    gpio_cfg_out(0);
    udelay(500);
    gpio_cfg_out(1);
    udelay(30);
    ret = gpio_cfg_in();
    udelay(500);
#if 0
    if (ret == 0) {
        printk("reset ok.\n");
    } else {
        printk("reset failed.\n");
    }
#endif
}

static void ds18b20_config_rel(unsigned char rel)
{
    ds18b20_reset();
    ds18b20_write8(SKIP_ROM);
    ds18b20_write8(WRITE_MEM);
    ds18b20_write8(TH);
    ds18b20_write8(TL);

    switch (rel) {
        case 9:
            ds18b20_write8(NINE_BIT);
            break;
        case 10:
            ds18b20_write8(TEN_BIT);
            break;
        case 11:
            ds18b20_write8(ELE_BIT);
            break;
        case 12:
            ds18b20_write8(TWL_BIT);
            break;
    }
}

static int ds18b20_open(struct inode *inode, struct file *file)
{
return 0;
}

static int ds18b20_release(struct inode *inode, struct file *file)
{
return 0;
}

void bubbleSort(int arr[], int count)
{
int i = count, j;
int temp;

    while (i > 0) {
        for (j=0; i
            if (arr[j] > arr[j+1]) {
                temp = arr[j];
                arr[j] = arr[j+1];
                arr[j+1] = temp;
            }
        }
        i--;
    }
}

static ssize_t ds18b20_read(struct file *file, char *buf, size_t count, loff_t *pos)
{
    unsigned char h8, l8;
    int i, temp = 0, tvalsum;
    int value[12];

    ds18b20_reset();
    ds18b20_write8(SKIP_ROM);
    ds18b20_write8(COVERTT);
    udelay(700);

mdelay(750);

    for (i=0; i<12; ++i) {
        ds18b20_reset();
        ds18b20_write8(SKIP_ROM);
        ds18b20_write8(READ_MEM);

l8 = ds18b20_read8();
h8 = ds18b20_read8();

        temp = (h8 << 8) | l8;
        if (temp & 0x8000) {
            temp = ~temp + 1;
        }
        temp *= 50;
        temp >>= 3;
        if ((temp > TEMP_H) || (temp < TEMP_L)) {
            --i;
            temp = 0;
            continue;
        }
        value[i] = temp;
    }

bubbleSort(value, 12);

    for (i=4, tvalsum=0; i<8; ++i) {
        tvalsum += value[i];
    }

    temp = (tvalsum) / 4;
    if(copy_to_user(buf, &temp, 4))
  return -EFAULT;
return count;
}

static int ds18b20_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
    unsigned char rel;
    if(copy_from_user(&rel, (unsigned char *)arg, 1))
  return -EFAULT;

    switch (cmd) {
        case DS18B20_RESET:
            ds18b20_reset();
            break;
        case DS18B20_REL:
            ds18b20_config_rel(rel);
            break;
        default:
            return -1;
    }

return 0;
}

static struct file_operations ds18b20_fops = {
    .owner = THIS_MODULE,
    .open = ds18b20_open,
    .release = ds18b20_release,
    .read = ds18b20_read,
    .unlocked_ioctl = ds18b20_ioctl,
};

static struct miscdevice ds18b20_miscdev = {
    .minor = MISC_DYNAMIC_MINOR,
    .name   = "ds18b20",
    .fops   = &ds18b20_fops,
};

static int ds18b20_init(void)
{
misc_register(&ds18b20_miscdev);

gpio_con = ioremap(0xe0200c20, 8);
gpio_dat = gpio_con + 1;

return 0;
}

static void ds18b20_exit(void)
{
iounmap(gpio_con);
misc_deregister(&ds18b20_miscdev);
}

module_init(ds18b20_init);
module_exit(ds18b20_exit);

********************************************************************************

Makefile文件

********************************************************************************

ifeq ($(KERNELRELEASE),)

KERNELDIR ?= /home/linux/linux-3.0.8/
PWD := $(shell pwd)

modules:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules

modules_install:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install

test:test.c

clean:
rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions Module* module* test

.PHONY: modules modules_install clean

else
obj-m := ds18b20_drv.o
endif

********************************************************************************

测试代码：test

********************************************************************************

#include
#include
#include
#include
#include
#include
#include

#define DS18B20_RESET 0x10001
#define DS18B20_REL 0x10002

int main(int argc, char *argv[])
{
int fd;
int data;
unsigned char relbit;

fd = open("/dev/ds18b20", O_RDWR);
if (fd < 0)
{
  printf("open ds18b20 failed.\n");
  exit(-1);
}
if (argc < 2)
{
  printf("usage:\n %s <9|10|11|12>\n", argv[0]);
  exit(-1);
}
relbit = strtoul(argv[1], NULL, 10);
while (1) {
  ioctl(fd, DS18B20_REL, &relbit);
  read(fd, &data, sizeof(data));
  usleep(200000);
  printf("%f\n", (float)data / 100);
}
close(fd);
return 0;
}