127 lines
2.3 KiB
C
127 lines
2.3 KiB
C
/*
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* SPDX-License-Identifier: GPL-2.0+
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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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