#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/miscdevice.h>
#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;
}
/* 鍙傜湅鏂囨。P16,娉ㄦ剰鍐?鍜?鐨勬椂闅欒姹?/
static void ds18b20_write8(unsigned char data)
{
int i;
for (i = 0; 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;
}
}
/* 鍙傜湅鏂囨。P16,娉ㄦ剰璇?鍜?鐨勬椂闅欒姹?/
static unsigned char ds18b20_read8(void)
{
int i;
unsigned char bit;
unsigned char data = 0;
for (i = 0; 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;
}
/* 鍙傜湅鏂囨。P15*/
static void ds18b20_reset(void)
{
unsigned char ret;
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_close(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; j < i - 1; j++)
{
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;
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_close,
.read = ds18b20_read,
.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);
MODULE_LICENSE("GPL");
********************************************************************************
测试代码：
********************************************************************************
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdlib.h>
#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;
}