140 lines
2.3 KiB
C
Executable File
140 lines
2.3 KiB
C
Executable File
#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/ioctl.h>
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#include <linux/delay.h>
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#include <linux/gpio.h>
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#include <linux/of_gpio.h>
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unsigned int gpio_num = 223;
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#define DQ_IN gpio_direction_input(gpio_num)
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#define DQ_OUT gpio_direction_output(gpio_num, gpio_get_value(gpio_num))
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#define DQ_H gpio_set_value(gpio_num, 1)
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#define DQ_L gpio_set_value(gpio_num, 0)
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#define DQ_V gpio_get_value(gpio_num)
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spinlock_t lock;
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//********************************
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//功能:ds18b20复位
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//********************************
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int init_DS18B20(void)
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{
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unsigned int result;
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DQ_OUT;
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DQ_L;
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DQ_H;
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udelay(2);
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DQ_L;
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udelay(480); //480~960
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DQ_H;
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udelay(60); //60-240
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DQ_IN;
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result = DQ_V;
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udelay(420);
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DQ_OUT;
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printk("ds18b20 init result %d", result);
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return result;
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}
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//*************************************
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//功能:从ds18b20读一个字节的数据
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//*************************************
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unsigned char read_char(void)
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{
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unsigned int i = 0;
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unsigned char dat = 0;
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spin_lock(&lock);
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for(i=0; i<8; i++) {
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DQ_OUT;
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DQ_L;
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DQ_H;
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udelay(2);
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DQ_L;
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udelay(2);
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DQ_H;
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udelay(8);
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dat >>= 1;
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DQ_IN;
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if (DQ_V)
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dat |= 0x80;
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udelay(50);
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}
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DQ_OUT;
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DQ_L;
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DQ_H;
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spin_unlock(&lock);
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return dat;
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}
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//*************************************
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//功能:向ds18b20写一个字节的数据
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//*************************************
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void write_char(unsigned char dat)
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{
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unsigned int i = 0;
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spin_lock(&lock);
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DQ_OUT;
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DQ_H;
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for(i=0; i<8; i++)
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{
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DQ_H;
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udelay(2);
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DQ_L;
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if (dat & 0x01)
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DQ_H;
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else
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DQ_L;
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udelay(60);
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dat >>= 1;
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}
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DQ_H;
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spin_unlock(&lock);
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}
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int initDs18b20(unsigned int gpioNum)
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{
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spin_lock_init(&lock);
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gpio_num = gpioNum;
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if (init_DS18B20())
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return 1;
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return 0;
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}
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/*读取数据*/
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void readDs18b20Data(unsigned char *value)
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{
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if (init_DS18B20())
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{
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return;
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}
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write_char(0xCC);
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write_char(0x44);
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mdelay(800);
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if (init_DS18B20())
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{
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return;
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}
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write_char(0xCC);
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write_char(0xBE);
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if (sizeof(&value) > 1)
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{
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value[0] = read_char();
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value[1] = read_char();
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}
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}
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void freeDs18b20(void)
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{
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gpio_free(gpio_num);
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}
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