dtt/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 #ifdef CONFIG_DTT_LM75
  31 #if !defined(CFG_EEPROM_PAGE_WRITE_ENABLE) || \
  32         (CFG_EEPROM_PAGE_WRITE_BITS < 1)
  33 # 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"
  34 #endif
  35
  36 #include <i2c.h>
  37 #include <dtt.h>
  38
  39
  40 /*
  41  * Device code
  42  */
  43 #define DTT_I2C_DEV_CODE 0x48                   /* ON Semi's LM75 device */
  44
  45 int dtt_read(int sensor, int reg)
  46 {
  47     int dlen;
  48     uchar data[2];
  49
  50     /*
  51      * Validate 'reg' param
  52      */
  53     if((reg < 0) || (reg > 3))
  54         return -1;
  55
  56     /*
  57      * Calculate sensor address and register.
  58      */
  59     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* calculate address of lm75 */
  60
  61     /*
  62      * Prepare to handle 2 byte result.
  63      */
  64     if ((reg == DTT_READ_TEMP) ||
  65         (reg == DTT_TEMP_HYST) ||
  66         (reg == DTT_TEMP_SET))
  67         dlen = 2;
  68     else
  69         dlen = 1;
  70
  71     /*
  72      * Now try to read the register.
  73      */
  74     if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  75         return -1;
  76
  77     /*
  78      * Handle 2 byte result.
  79      */
  80     if (dlen == 2)
  81         return ((int)((short)data[1] + (((short)data[0]) << 8)));
  82
  83
  84     return (int)data[0];
  85 } /* dtt_read() */
  86
  87
  88 int dtt_write(int sensor, int reg, int val)
  89 {
  90     int dlen;
  91     uchar data[2];
  92
  93     /*
  94      * Validate 'reg' param
  95      */
  96     if ((reg < 0) || (reg > 3))
  97         return 1;
  98
  99     /*
 100      * Calculate sensor address and register.
 101      */
 102     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* calculate address of lm75 */
 103
 104     /*
 105      * Handle 2 byte values.
 106      */
 107     if ((reg == DTT_READ_TEMP) ||
 108         (reg == DTT_TEMP_HYST) ||
 109         (reg == DTT_TEMP_SET)) {
 110         dlen = 2;
 111         data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
 112         data[1] = (char)(val & 0xff);
 113     } else {
 114         dlen = 1;
 115         data[0] = (char)(val & 0xff);
 116     }
 117
 118     /*
 119      * Write value to register.
 120      */
 121     if (i2c_write(sensor, reg, 1, data, dlen) != 0)
 122         return 1;
 123
 124     return 0;
 125 } /* dtt_write() */
 126
 127
 128 static int _dtt_init(int sensor)
 129 {
 130     int val;
 131
 132     /*
 133      * Setup TSET ( trip point ) register
 134      */
 135     val = ((CFG_DTT_MAX_TEMP * 2) << 7) & 0xff80; /* trip */
 136     if (dtt_write(sensor, DTT_TEMP_SET, val) != 0)
 137         return 1;
 138
 139     /*
 140      * Setup THYST ( untrip point ) register - Hysteresis
 141      */
 142     val = (((CFG_DTT_MAX_TEMP - CFG_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 143     if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
 144         return 1;
 145
 146     /*
 147      * Setup configuraton register
 148      */
 149     /* config = 6 sample integration, int mode, active low, and enable */
 150     val = 0x18;
 151     if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 152         return 1;
 153
 154     return 0;
 155 } /* _dtt_init() */
 156
 157
 158 int dtt_init (void)
 159 {
 160     int i;
 161     unsigned char sensors[] = CONFIG_DTT_SENSORS;
 162     const char *const header = "DTT:   ";
 163
 164     for (i = 0; i < sizeof(sensors); i++) {
 165         if (_dtt_init(sensors[i]) != 0)
 166             printf("%s%d FAILED INIT\n", header, i+1);
 167         else
 168             printf("%s%d is %i C\n", header, i+1,
 169                    dtt_get_temp(sensors[i]));
 170     }
 171
 172     return (0);
 173 } /* dtt_init() */
 174
 175 int dtt_get_temp(int sensor)
 176 {
 177     return (dtt_read(sensor, DTT_READ_TEMP) / 256);
 178 } /* dtt_get_temp() */
 179
 180 #endif /* CONFIG_DTT_LM75 */