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https://github.com/u-boot/u-boot.git
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780f13a9e1
The U-Boot Design Principles[1] clearly say: Initialize devices only when they are needed within U-Boot, i.e. don't initialize the Ethernet interface(s) unless U-Boot performs a download over Ethernet; don't initialize any IDE or USB devices unless U-Boot actually tries to load files from these, etc. (and don't forget to shut down these devices after using them - otherwise nasty things may happen when you try to boot your OS). So, do not initialize and read the sensors on startup. Signed-off-by: Heiko Schocher <hs@denx.de> cc: Wolfgang Denk <wd@denx.de> cc: Holger Brunck <holger.brunck@keymile.com>
172 lines
3.9 KiB
C
172 lines
3.9 KiB
C
/*
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* (C) Copyright 2001
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* Erik Theisen, Wave 7 Optics, etheisen@mindspring.com.
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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/*
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* Dallas Semiconductor's DS1621/1631 Digital Thermometer and Thermostat.
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*/
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#include <common.h>
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#include <i2c.h>
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#include <dtt.h>
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/*
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* Device code
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*/
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#define DTT_I2C_DEV_CODE 0x48 /* Dallas Semi's DS1621 */
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#define DTT_READ_TEMP 0xAA
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#define DTT_READ_COUNTER 0xA8
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#define DTT_READ_SLOPE 0xA9
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#define DTT_WRITE_START_CONV 0xEE
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#define DTT_WRITE_STOP_CONV 0x22
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#define DTT_TEMP_HIGH 0xA1
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#define DTT_TEMP_LOW 0xA2
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#define DTT_CONFIG 0xAC
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/*
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* Config register bits
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*/
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#define DTT_CONFIG_1SHOT 0x01
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#define DTT_CONFIG_POLARITY 0x02
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#define DTT_CONFIG_R0 0x04 /* ds1631 only */
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#define DTT_CONFIG_R1 0x08 /* ds1631 only */
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#define DTT_CONFIG_NVB 0x10
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#define DTT_CONFIG_TLF 0x20
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#define DTT_CONFIG_THF 0x40
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#define DTT_CONFIG_DONE 0x80
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int dtt_read(int sensor, int reg)
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{
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int dlen;
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uchar data[2];
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/* Calculate sensor address and command */
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sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1621*/
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/* Prepare to handle 2 byte result */
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switch(reg) {
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case DTT_READ_TEMP:
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case DTT_TEMP_HIGH:
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case DTT_TEMP_LOW:
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dlen = 2;
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break;
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default:
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dlen = 1;
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}
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/* Now try to read the register */
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if (i2c_read(sensor, reg, 1, data, dlen) != 0)
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return 1;
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/* Handle 2 byte result */
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if (dlen == 2)
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return (short)((data[0] << 8) | data[1]);
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return (int)data[0];
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}
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int dtt_write(int sensor, int reg, int val)
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{
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int dlen;
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uchar data[2];
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/* Calculate sensor address and register */
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sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
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/* Handle various data sizes. */
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switch(reg) {
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case DTT_READ_TEMP:
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case DTT_TEMP_HIGH:
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case DTT_TEMP_LOW:
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dlen = 2;
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data[0] = (char)((val >> 8) & 0xff); /* MSB first */
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data[1] = (char)(val & 0xff);
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break;
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case DTT_WRITE_START_CONV:
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case DTT_WRITE_STOP_CONV:
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dlen = 0;
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data[0] = (char)0;
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data[1] = (char)0;
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break;
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default:
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dlen = 1;
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data[0] = (char)(val & 0xff);
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}
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/* Write value to device */
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if (i2c_write(sensor, reg, 1, data, dlen) != 0)
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return 1;
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/* Poll NV memory busy bit in case write was to register stored in EEPROM */
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while(i2c_reg_read(sensor, DTT_CONFIG) & DTT_CONFIG_NVB)
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;
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return 0;
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}
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int dtt_init_one(int sensor)
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{
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int val;
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/* Setup High Temp */
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val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80;
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if (dtt_write(sensor, DTT_TEMP_HIGH, val) != 0)
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return 1;
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/* Setup Low Temp - hysteresis */
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val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
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if (dtt_write(sensor, DTT_TEMP_LOW, val) != 0)
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return 1;
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/*
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* Setup configuraton register
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*
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* Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES
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*
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* We run in polled mode, since there isn't any way to know if this
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* lousy device is ready to provide temperature readings on power up.
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*/
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val = 0x9;
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if (dtt_write(sensor, DTT_CONFIG, val) != 0)
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return 1;
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return 0;
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}
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int dtt_get_temp(int sensor)
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{
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int i;
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/* Start a conversion, may take up to 1 second. */
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dtt_write(sensor, DTT_WRITE_START_CONV, 0);
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for (i = 0; i <= 10; i++) {
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udelay(100000);
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if (dtt_read(sensor, DTT_CONFIG) & DTT_CONFIG_DONE)
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break;
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}
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return (dtt_read(sensor, DTT_READ_TEMP) / 256);
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}
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