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bootloader/u-boot_2015_04/drivers/hwmon/ds620.c 1.46 KB
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  /*
   * DS620 DTT support
   *
   * (C) Copyright 2014 3ADEV <http://www.3adev.com>
   * Written-by: Albert ARIBAUD <albert.aribaud@3adev.fr>
   *
   * SPDX-License-Identifier:	GPL-2.0+
   */
  
  /*
   * 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
  #define DTT_START_CONVERT	0x51
  #define DTT_TEMP		0xAA
  #define DTT_CONFIG		0xAC
  
  /*
   * Config register MSB bits
   */
  #define DTT_CONFIG_1SHOT	0x01
  #define DTT_CONFIG_AUTOC	0x02
  #define DTT_CONFIG_R0		0x04 /* always 1 */
  #define DTT_CONFIG_R1		0x08 /* always 1 */
  #define DTT_CONFIG_TLF	0x10
  #define DTT_CONFIG_THF	0x20
  #define DTT_CONFIG_NVB	0x40
  #define DTT_CONFIG_DONE	0x80
  
  #define CHIP(sensor) (DTT_I2C_DEV_CODE + (sensor & 0x07))
  
  int dtt_init_one(int sensor)
  {
  	uint8_t config = DTT_CONFIG_1SHOT
  			| DTT_CONFIG_R0
  			| DTT_CONFIG_R1;
  	return i2c_write(CHIP(sensor), DTT_CONFIG, 1, &config, 1);
  }
  
  int dtt_get_temp(int sensor)
  {
  	uint8_t status;
  	uint8_t temp[2];
  
  	/* Start a conversion, may take up to 1 second. */
  	i2c_write(CHIP(sensor), DTT_START_CONVERT, 1, NULL, 0);
  	do {
  		if (i2c_read(CHIP(sensor), DTT_CONFIG, 1, &status, 1))
  			/* bail out if I2C error */
  			status |= DTT_CONFIG_DONE;
  	} while (!(status & DTT_CONFIG_DONE));
  	if (i2c_read(CHIP(sensor), DTT_TEMP, 1, temp, 2))
  		/* bail out if I2C error */
  		return -274; /* below absolute zero == error */
  
  	return ((int16_t)(temp[1] | (temp[0] << 8))) >> 7;
  }