ds1775.c
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/*
* SPDX-License-Identifier: GPL-2.0+
*/
/*
* Dallas Semiconductor's DS1775 Digital Thermometer and Thermostat
*/
#include <common.h>
#include <i2c.h>
#include <dtt.h>
#define DTT_I2C_DEV_CODE CONFIG_SYS_I2C_DTT_ADDR /* Dallas Semi's DS1775 device code */
#define DTT_READ_TEMP 0x0
#define DTT_CONFIG 0x1
#define DTT_TEMP_HYST 0x2
#define DTT_TEMP_OS 0x3
int dtt_read(int sensor, int reg)
{
int dlen;
uchar data[2];
/*
* Calculate sensor address and command
*/
sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1775 */
/*
* Prepare to handle 2 byte result
*/
if ((reg == DTT_READ_TEMP) ||
(reg == DTT_TEMP_OS) || (reg == DTT_TEMP_HYST))
dlen = 2;
else
dlen = 1;
/*
* Now try to read the register
*/
if (i2c_read(sensor, reg, 1, data, dlen) != 0)
return 1;
/*
* Handle 2 byte result
*/
if (dlen == 2)
return ((int)((short)data[1] + (((short)data[0]) << 8)));
return (int) data[0];
}
int dtt_write(int sensor, int reg, int val)
{
int dlen;
uchar data[2];
/*
* Calculate sensor address and register
*/
sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
/*
* Handle various data sizes
*/
if ((reg == DTT_READ_TEMP) ||
(reg == DTT_TEMP_OS) || (reg == DTT_TEMP_HYST)) {
dlen = 2;
data[0] = (char)((val >> 8) & 0xff); /* MSB first */
data[1] = (char)(val & 0xff);
} else {
dlen = 1;
data[0] = (char)(val & 0xff);
}
/*
* Write value to device
*/
if (i2c_write(sensor, reg, 1, data, dlen) != 0)
return 1;
return 0;
}
int dtt_init_one(int sensor)
{
int val;
/*
* Setup High Temp
*/
val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80;
if (dtt_write(sensor, DTT_TEMP_OS, val) != 0)
return 1;
udelay(50000); /* Max 50ms */
/*
* Setup Low Temp - hysteresis
*/
val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
return 1;
udelay(50000); /* Max 50ms */
/*
* Setup configuraton register
*
* Fault Tolerance limits 4, Thermometer resolution bits is 9,
* Polarity = Active Low,continuous conversion mode, Thermostat
* mode is interrupt mode
*/
val = 0xa;
if (dtt_write(sensor, DTT_CONFIG, val) != 0)
return 1;
udelay(50000); /* Max 50ms */
return 0;
}
int dtt_get_temp(int sensor)
{
return (dtt_read(sensor, DTT_READ_TEMP) / 256);
}