drivers/hwmon/ds1775.c

   1 /*
   2  * SPDX-License-Identifier:     GPL-2.0+
   3  */
   4
   5 /*
   6  * Dallas Semiconductor's DS1775 Digital Thermometer and Thermostat
   7  */
   8
   9 #include <common.h>
  10
  11 #include <i2c.h>
  12 #include <dtt.h>
  13
  14 #define DTT_I2C_DEV_CODE        0x48 /* Dallas Semi's DS1775 device code */
  15 #define DTT_READ_TEMP           0x0
  16 #define DTT_CONFIG              0x1
  17 #define DTT_TEMP_HYST           0x2
  18 #define DTT_TEMP_OS             0x3
  19
  20 int dtt_read(int sensor, int reg)
  21 {
  22         int dlen;
  23         uchar data[2];
  24
  25         /*
  26          * Calculate sensor address and command
  27          */
  28         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1775 */
  29
  30         /*
  31          * Prepare to handle 2 byte result
  32          */
  33         if ((reg == DTT_READ_TEMP) ||
  34             (reg == DTT_TEMP_OS) || (reg == DTT_TEMP_HYST))
  35                 dlen = 2;
  36         else
  37                 dlen = 1;
  38
  39         /*
  40          * Now try to read the register
  41          */
  42         if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  43                 return 1;
  44
  45         /*
  46          * Handle 2 byte result
  47          */
  48         if (dlen == 2)
  49                 return ((int)((short)data[1] + (((short)data[0]) << 8)));
  50
  51         return (int) data[0];
  52 }
  53
  54
  55 int dtt_write(int sensor, int reg, int val)
  56 {
  57         int dlen;
  58         uchar data[2];
  59
  60         /*
  61          * Calculate sensor address and register
  62          */
  63         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  64
  65         /*
  66          * Handle various data sizes
  67          */
  68         if ((reg == DTT_READ_TEMP) ||
  69             (reg == DTT_TEMP_OS) || (reg == DTT_TEMP_HYST)) {
  70                 dlen = 2;
  71                 data[0] = (char)((val >> 8) & 0xff); /* MSB first */
  72                 data[1] = (char)(val & 0xff);
  73         } else {
  74                 dlen = 1;
  75                 data[0] = (char)(val & 0xff);
  76         }
  77
  78         /*
  79          * Write value to device
  80          */
  81         if (i2c_write(sensor, reg, 1, data, dlen) != 0)
  82                 return 1;
  83
  84         return 0;
  85 }
  86
  87
  88 int dtt_init_one(int sensor)
  89 {
  90         int val;
  91
  92         /*
  93          * Setup High Temp
  94          */
  95         val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80;
  96         if (dtt_write(sensor, DTT_TEMP_OS, val) != 0)
  97                 return 1;
  98         udelay(50000);                  /* Max 50ms */
  99
 100         /*
 101          * Setup Low Temp - hysteresis
 102          */
 103         val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 104         if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
 105                 return 1;
 106         udelay(50000);                  /* Max 50ms */
 107
 108         /*
 109          * Setup configuraton register
 110          *
 111          * Fault Tolerance limits 4, Thermometer resolution bits is 9,
 112          * Polarity = Active Low,continuous conversion mode, Thermostat
 113          * mode is interrupt mode
 114          */
 115         val = 0xa;
 116         if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 117                 return 1;
 118         udelay(50000);                  /* Max 50ms */
 119
 120         return 0;
 121 }
 122
 123 int dtt_get_temp(int sensor)
 124 {
 125         return (dtt_read(sensor, DTT_READ_TEMP) / 256);
 126 }