drivers/hwmon/lm75.c

   1 /*
   2  * (C) Copyright 2001
   3  * Bill Hunter,  Wave 7 Optics, williamhunter@mediaone.net
   4  *
   5  * See file CREDITS for list of people who contributed to this
   6  * project.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License as
  10  * published by the Free Software Foundation; either version 2 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  21  * MA 02111-1307 USA
  22  */
  23
  24 /*
  25  * On Semiconductor's LM75 Temperature Sensor
  26  */
  27
  28 #include <common.h>
  29
  30 #if !defined(CFG_EEPROM_PAGE_WRITE_ENABLE) || \
  31         (CFG_EEPROM_PAGE_WRITE_BITS < 1)
  32 # error "CFG_EEPROM_PAGE_WRITE_ENABLE must be defined and CFG_EEPROM_PAGE_WRITE_BITS must be greater than  1 to use CONFIG_DTT_LM75"
  33 #endif
  34
  35 #include <i2c.h>
  36 #include <dtt.h>
  37
  38 /*
  39  * Device code
  40  */
  41 #define DTT_I2C_DEV_CODE 0x48                   /* ON Semi's LM75 device */
  42 #define DTT_READ_TEMP           0x0
  43 #define DTT_CONFIG              0x1
  44 #define DTT_TEMP_HYST           0x2
  45 #define DTT_TEMP_SET            0x3
  46
  47 int dtt_read(int sensor, int reg)
  48 {
  49     int dlen;
  50     uchar data[2];
  51
  52 #ifdef CONFIG_DTT_AD7414
  53     /*
  54      * On AD7414 the first value upon bootup is not read correctly.
  55      * This is most likely because of the 800ms update time of the
  56      * temp register in normal update mode. To get current values
  57      * each time we issue the "dtt" command including upon powerup
  58      * we switch into one-short mode.
  59      *
  60      * Issue one-shot mode command
  61      */
  62     dtt_write(sensor, DTT_CONFIG, 0x64);
  63 #endif
  64
  65     /*
  66      * Validate 'reg' param
  67      */
  68     if((reg < 0) || (reg > 3))
  69         return -1;
  70
  71     /*
  72      * Calculate sensor address and register.
  73      */
  74     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* calculate address of lm75 */
  75
  76     /*
  77      * Prepare to handle 2 byte result.
  78      */
  79     if ((reg == DTT_READ_TEMP) ||
  80         (reg == DTT_TEMP_HYST) ||
  81         (reg == DTT_TEMP_SET))
  82         dlen = 2;
  83     else
  84         dlen = 1;
  85
  86     /*
  87      * Now try to read the register.
  88      */
  89     if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  90         return -1;
  91
  92     /*
  93      * Handle 2 byte result.
  94      */
  95     if (dlen == 2)
  96         return ((int)((short)data[1] + (((short)data[0]) << 8)));
  97
  98
  99     return (int)data[0];
 100 } /* dtt_read() */
 101
 102
 103 int dtt_write(int sensor, int reg, int val)
 104 {
 105     int dlen;
 106     uchar data[2];
 107
 108     /*
 109      * Validate 'reg' param
 110      */
 111     if ((reg < 0) || (reg > 3))
 112         return 1;
 113
 114     /*
 115      * Calculate sensor address and register.
 116      */
 117     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* calculate address of lm75 */
 118
 119     /*
 120      * Handle 2 byte values.
 121      */
 122     if ((reg == DTT_READ_TEMP) ||
 123         (reg == DTT_TEMP_HYST) ||
 124         (reg == DTT_TEMP_SET)) {
 125         dlen = 2;
 126         data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
 127         data[1] = (char)(val & 0xff);
 128     } else {
 129         dlen = 1;
 130         data[0] = (char)(val & 0xff);
 131     }
 132
 133     /*
 134      * Write value to register.
 135      */
 136     if (i2c_write(sensor, reg, 1, data, dlen) != 0)
 137         return 1;
 138
 139     return 0;
 140 } /* dtt_write() */
 141
 142
 143 static int _dtt_init(int sensor)
 144 {
 145     int val;
 146
 147     /*
 148      * Setup TSET ( trip point ) register
 149      */
 150     val = ((CFG_DTT_MAX_TEMP * 2) << 7) & 0xff80; /* trip */
 151     if (dtt_write(sensor, DTT_TEMP_SET, val) != 0)
 152         return 1;
 153
 154     /*
 155      * Setup THYST ( untrip point ) register - Hysteresis
 156      */
 157     val = (((CFG_DTT_MAX_TEMP - CFG_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 158     if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
 159         return 1;
 160
 161     /*
 162      * Setup configuraton register
 163      */
 164 #ifdef CONFIG_DTT_AD7414
 165     /* config = alert active low and disabled */
 166     val = 0x60;
 167 #else
 168     /* config = 6 sample integration, int mode, active low, and enable */
 169     val = 0x18;
 170 #endif
 171     if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 172         return 1;
 173
 174     return 0;
 175 } /* _dtt_init() */
 176
 177
 178 int dtt_init (void)
 179 {
 180     int i;
 181     unsigned char sensors[] = CONFIG_DTT_SENSORS;
 182     const char *const header = "DTT:   ";
 183
 184     for (i = 0; i < sizeof(sensors); i++) {
 185         if (_dtt_init(sensors[i]) != 0)
 186             printf("%s%d FAILED INIT\n", header, i+1);
 187         else
 188             printf("%s%d is %i C\n", header, i+1,
 189                    dtt_get_temp(sensors[i]));
 190     }
 191
 192     return (0);
 193 } /* dtt_init() */
 194
 195 int dtt_get_temp(int sensor)
 196 {
 197     int const ret = dtt_read(sensor, DTT_READ_TEMP);
 198
 199     if (ret < 0) {
 200         printf("DTT temperature read failed.\n");
 201         return 0;
 202     }
 203     return (int)((int16_t) ret / 256);
 204 } /* dtt_get_temp() */