drivers/hwmon/ds620.c

   1 /*
   2  * DS620 DTT support
   3  *
   4  * (C) Copyright 2014 3ADEV <http://www.3adev.com>
   5  * Written-by: Albert ARIBAUD <albert.aribaud@3adev.fr>
   6  *
   7  * SPDX-License-Identifier:     GPL-2.0+
   8  */
   9
  10 /*
  11  * Dallas Semiconductor's DS1621/1631 Digital Thermometer and Thermostat.
  12  */
  13
  14 #include <common.h>
  15 #include <i2c.h>
  16 #include <dtt.h>
  17
  18 /*
  19  * Device code
  20  */
  21 #define DTT_I2C_DEV_CODE        0x48
  22 #define DTT_START_CONVERT       0x51
  23 #define DTT_TEMP                0xAA
  24 #define DTT_CONFIG              0xAC
  25
  26 /*
  27  * Config register MSB bits
  28  */
  29 #define DTT_CONFIG_1SHOT        0x01
  30 #define DTT_CONFIG_AUTOC        0x02
  31 #define DTT_CONFIG_R0           0x04 /* always 1 */
  32 #define DTT_CONFIG_R1           0x08 /* always 1 */
  33 #define DTT_CONFIG_TLF  0x10
  34 #define DTT_CONFIG_THF  0x20
  35 #define DTT_CONFIG_NVB  0x40
  36 #define DTT_CONFIG_DONE 0x80
  37
  38 #define CHIP(sensor) (DTT_I2C_DEV_CODE + (sensor & 0x07))
  39
  40 int dtt_init_one(int sensor)
  41 {
  42         uint8_t config = DTT_CONFIG_1SHOT
  43                         | DTT_CONFIG_R0
  44                         | DTT_CONFIG_R1;
  45         return i2c_write(CHIP(sensor), DTT_CONFIG, 1, &config, 1);
  46 }
  47
  48 int dtt_get_temp(int sensor)
  49 {
  50         uint8_t status;
  51         uint8_t temp[2];
  52
  53         /* Start a conversion, may take up to 1 second. */
  54         i2c_write(CHIP(sensor), DTT_START_CONVERT, 1, NULL, 0);
  55         do {
  56                 if (i2c_read(CHIP(sensor), DTT_CONFIG, 1, &status, 1))
  57                         /* bail out if I2C error */
  58                         status |= DTT_CONFIG_DONE;
  59         } while (!(status & DTT_CONFIG_DONE));
  60         if (i2c_read(CHIP(sensor), DTT_TEMP, 1, temp, 2))
  61                 /* bail out if I2C error */
  62                 return -274; /* below absolute zero == error */
  63
  64         return ((int16_t)(temp[1] | (temp[0] << 8))) >> 7;
  65 }