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 #if defined(CONFIG_SYS_I2C_DTT_ADDR)
  20 #define DTT_I2C_DEV_CODE CONFIG_SYS_I2C_DTT_ADDR
  21 #else
  22 #define DTT_I2C_DEV_CODE 0x48                   /* ON Semi's LM75 device */
  23 #endif
  24 #define DTT_READ_TEMP           0x0
  25 #define DTT_CONFIG              0x1
  26 #define DTT_TEMP_HYST           0x2
  27 #define DTT_TEMP_SET            0x3
  28
  29 int dtt_read(int sensor, int reg)
  30 {
  31         int dlen;
  32         uchar data[2];
  33
  34 #ifdef CONFIG_DTT_AD7414
  35         /*
  36          * On AD7414 the first value upon bootup is not read correctly.
  37          * This is most likely because of the 800ms update time of the
  38          * temp register in normal update mode. To get current values
  39          * each time we issue the "dtt" command including upon powerup
  40          * we switch into one-short mode.
  41          *
  42          * Issue one-shot mode command
  43          */
  44         dtt_write(sensor, DTT_CONFIG, 0x64);
  45 #endif
  46
  47         /* Validate 'reg' param */
  48         if((reg < 0) || (reg > 3))
  49                 return -1;
  50
  51         /* Calculate sensor address and register. */
  52         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  53
  54         /* Prepare to handle 2 byte result. */
  55         if ((reg == DTT_READ_TEMP) ||
  56                 (reg == DTT_TEMP_HYST) ||
  57                 (reg == DTT_TEMP_SET))
  58                         dlen = 2;
  59         else
  60                 dlen = 1;
  61
  62         /* Now try to read the register. */
  63         if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  64                 return -1;
  65
  66         /* Handle 2 byte result. */
  67         if (dlen == 2)
  68                 return ((int)((short)data[1] + (((short)data[0]) << 8)));
  69
  70         return (int)data[0];
  71 } /* dtt_read() */
  72
  73
  74 int dtt_write(int sensor, int reg, int val)
  75 {
  76         int dlen;
  77         uchar data[2];
  78
  79         /* Validate 'reg' param */
  80         if ((reg < 0) || (reg > 3))
  81                 return 1;
  82
  83         /* Calculate sensor address and register. */
  84         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  85
  86         /* Handle 2 byte values. */
  87         if ((reg == DTT_READ_TEMP) ||
  88                 (reg == DTT_TEMP_HYST) ||
  89                 (reg == DTT_TEMP_SET)) {
  90                         dlen = 2;
  91                 data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
  92                 data[1] = (char)(val & 0xff);
  93         } else {
  94                 dlen = 1;
  95                 data[0] = (char)(val & 0xff);
  96         }
  97
  98         /* Write value to register. */
  99         if (i2c_write(sensor, reg, 1, data, dlen) != 0)
 100                 return 1;
 101
 102         return 0;
 103 } /* dtt_write() */
 104
 105
 106 int dtt_init_one(int sensor)
 107 {
 108         int val;
 109
 110         /* Setup TSET ( trip point ) register */
 111         val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80; /* trip */
 112         if (dtt_write(sensor, DTT_TEMP_SET, val) != 0)
 113                 return 1;
 114
 115         /* Setup THYST ( untrip point ) register - Hysteresis */
 116         val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 117         if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
 118                 return 1;
 119
 120         /* Setup configuraton register */
 121 #ifdef CONFIG_DTT_AD7414
 122         /* config = alert active low and disabled */
 123         val = 0x60;
 124 #else
 125         /* config = 6 sample integration, int mode, active low, and enable */
 126         val = 0x18;
 127 #endif
 128         if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 129                 return 1;
 130
 131         return 0;
 132 } /* dtt_init_one() */
 133
 134 int dtt_get_temp(int sensor)
 135 {
 136         int const ret = dtt_read(sensor, DTT_READ_TEMP);
 137
 138         if (ret < 0) {
 139                 printf("DTT temperature read failed.\n");
 140                 return 0;
 141         }
 142         return (int)((int16_t) ret / 256);
 143 } /* dtt_get_temp() */