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/*
* (C) Copyright 2001
* Erik Theisen, Wave 7 Optics, etheisen@mindspring.com.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/*
* Dallas Semiconductor's DS1621/1631 Digital Thermometer and Thermostat.
*/
#include <common.h>
#include <i2c.h>
#include <dtt.h>
/*
* Device code
*/
#define DTT_I2C_DEV_CODE 0x48 /* Dallas Semi's DS1621 */
#define DTT_READ_TEMP 0xAA
#define DTT_READ_COUNTER 0xA8
#define DTT_READ_SLOPE 0xA9
#define DTT_WRITE_START_CONV 0xEE
#define DTT_WRITE_STOP_CONV 0x22
#define DTT_TEMP_HIGH 0xA1
#define DTT_TEMP_LOW 0xA2
#define DTT_CONFIG 0xAC
/*
* Config register bits
*/
#define DTT_CONFIG_1SHOT 0x01
#define DTT_CONFIG_POLARITY 0x02
#define DTT_CONFIG_R0 0x04 /* ds1631 only */
#define DTT_CONFIG_R1 0x08 /* ds1631 only */
#define DTT_CONFIG_NVB 0x10
#define DTT_CONFIG_TLF 0x20
#define DTT_CONFIG_THF 0x40
#define DTT_CONFIG_DONE 0x80
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 ds1621*/
/* Prepare to handle 2 byte result */
switch(reg) {
case DTT_READ_TEMP:
case DTT_TEMP_HIGH:
case DTT_TEMP_LOW:
dlen = 2;
break;
default:
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 (short)((data[0] << 8) | data[1]);
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. */
switch(reg) {
case DTT_READ_TEMP:
case DTT_TEMP_HIGH:
case DTT_TEMP_LOW:
dlen = 2;
data[0] = (char)((val >> 8) & 0xff); /* MSB first */
data[1] = (char)(val & 0xff);
break;
case DTT_WRITE_START_CONV:
case DTT_WRITE_STOP_CONV:
dlen = 0;
data[0] = (char)0;
data[1] = (char)0;
break;
default:
dlen = 1;
data[0] = (char)(val & 0xff);
}
/* Write value to device */
if (i2c_write(sensor, reg, 1, data, dlen) != 0)
return 1;
/* Poll NV memory busy bit in case write was to register stored in EEPROM */
while(i2c_reg_read(sensor, DTT_CONFIG) & DTT_CONFIG_NVB)
;
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_HIGH, val) != 0)
return 1;
/* Setup Low Temp - hysteresis */
val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
if (dtt_write(sensor, DTT_TEMP_LOW, val) != 0)
return 1;
/*
* Setup configuraton register
*
* Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES
*
* We run in polled mode, since there isn't any way to know if this
* lousy device is ready to provide temperature readings on power up.
*/
val = 0x9;
if (dtt_write(sensor, DTT_CONFIG, val) != 0)
return 1;
return 0;
}
int dtt_get_temp(int sensor)
{
int i;
/* Start a conversion, may take up to 1 second. */
dtt_write(sensor, DTT_WRITE_START_CONV, 0);
for (i = 0; i <= 10; i++) {
udelay(100000);
if (dtt_read(sensor, DTT_CONFIG) & DTT_CONFIG_DONE)
break;
}
return (dtt_read(sensor, DTT_READ_TEMP) / 256);
}
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