drivers/hwmon/lm75.c

   1 /*
   2  * (C) Copyright 2001
   3  * Bill Hunter,  Wave 7 Optics, williamhunter@mediaone.net
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 /*
   9  * On Semiconductor's LM75 Temperature Sensor
  10  */
  11
  12 #include <common.h>
  13 #include <i2c.h>
  14 #include <dtt.h>
  15
  16 /*
  17  * Device code
  18  */
  19 #define DTT_I2C_DEV_CODE 0x48                   /* ON Semi's LM75 device */
  20 #define DTT_READ_TEMP           0x0
  21 #define DTT_CONFIG              0x1
  22 #define DTT_TEMP_HYST           0x2
  23 #define DTT_TEMP_SET            0x3
  24
  25 int dtt_read(int sensor, int reg)
  26 {
  27         int dlen;
  28         uchar data[2];
  29
  30 #ifdef CONFIG_DTT_AD7414
  31         /*
  32          * On AD7414 the first value upon bootup is not read correctly.
  33          * This is most likely because of the 800ms update time of the
  34          * temp register in normal update mode. To get current values
  35          * each time we issue the "dtt" command including upon powerup
  36          * we switch into one-short mode.
  37          *
  38          * Issue one-shot mode command
  39          */
  40         dtt_write(sensor, DTT_CONFIG, 0x64);
  41 #endif
  42
  43         /* Validate 'reg' param */
  44         if((reg < 0) || (reg > 3))
  45                 return -1;
  46
  47         /* Calculate sensor address and register. */
  48         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  49
  50         /* Prepare to handle 2 byte result. */
  51         if ((reg == DTT_READ_TEMP) ||
  52                 (reg == DTT_TEMP_HYST) ||
  53                 (reg == DTT_TEMP_SET))
  54                         dlen = 2;
  55         else
  56                 dlen = 1;
  57
  58         /* Now try to read the register. */
  59         if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  60                 return -1;
  61
  62         /* Handle 2 byte result. */
  63         if (dlen == 2)
  64                 return ((int)((short)data[1] + (((short)data[0]) << 8)));
  65
  66         return (int)data[0];
  67 } /* dtt_read() */
  68
  69
  70 int dtt_write(int sensor, int reg, int val)
  71 {
  72         int dlen;
  73         uchar data[2];
  74
  75         /* Validate 'reg' param */
  76         if ((reg < 0) || (reg > 3))
  77                 return 1;
  78
  79         /* Calculate sensor address and register. */
  80         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  81
  82         /* Handle 2 byte values. */
  83         if ((reg == DTT_READ_TEMP) ||
  84                 (reg == DTT_TEMP_HYST) ||
  85                 (reg == DTT_TEMP_SET)) {
  86                         dlen = 2;
  87                 data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
  88                 data[1] = (char)(val & 0xff);
  89         } else {
  90                 dlen = 1;
  91                 data[0] = (char)(val & 0xff);
  92         }
  93
  94         /* Write value to register. */
  95         if (i2c_write(sensor, reg, 1, data, dlen) != 0)
  96                 return 1;
  97
  98         return 0;
  99 } /* dtt_write() */
 100
 101
 102 int dtt_init_one(int sensor)
 103 {
 104         int val;
 105
 106         /* Setup TSET ( trip point ) register */
 107         val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80; /* trip */
 108         if (dtt_write(sensor, DTT_TEMP_SET, val) != 0)
 109                 return 1;
 110
 111         /* Setup THYST ( untrip point ) register - Hysteresis */
 112         val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 113         if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
 114                 return 1;
 115
 116         /* Setup configuraton register */
 117 #ifdef CONFIG_DTT_AD7414
 118         /* config = alert active low and disabled */
 119         val = 0x60;
 120 #else
 121         /* config = 6 sample integration, int mode, active low, and enable */
 122         val = 0x18;
 123 #endif
 124         if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 125                 return 1;
 126
 127         return 0;
 128 } /* dtt_init_one() */
 129
 130 int dtt_get_temp(int sensor)
 131 {
 132         int const ret = dtt_read(sensor, DTT_READ_TEMP);
 133
 134         if (ret < 0) {
 135                 printf("DTT temperature read failed.\n");
 136                 return 0;
 137         }
 138         return (int)((int16_t) ret / 256);
 139 } /* dtt_get_temp() */