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