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 #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 #ifdef CONFIG_DTT_AD7414
  51     /*
  52      * On AD7414 the first value upon bootup is not read correctly.
  53      * This is most likely because of the 800ms update time of the
  54      * temp register in normal update mode. To get current values
  55      * each time we issue the "dtt" command including upon powerup
  56      * we switch into one-short mode.
  57      *
  58      * Issue one-shot mode command
  59      */
  60     dtt_write(sensor, DTT_CONFIG, 0x64);
  61 #endif
  62
  63     /*
  64      * Validate 'reg' param
  65      */
  66     if((reg < 0) || (reg > 3))
  67         return -1;
  68
  69     /*
  70      * Calculate sensor address and register.
  71      */
  72     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* calculate address of lm75 */
  73
  74     /*
  75      * Prepare to handle 2 byte result.
  76      */
  77     if ((reg == DTT_READ_TEMP) ||
  78         (reg == DTT_TEMP_HYST) ||
  79         (reg == DTT_TEMP_SET))
  80         dlen = 2;
  81     else
  82         dlen = 1;
  83
  84     /*
  85      * Now try to read the register.
  86      */
  87     if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  88         return -1;
  89
  90     /*
  91      * Handle 2 byte result.
  92      */
  93     if (dlen == 2)
  94         return ((int)((short)data[1] + (((short)data[0]) << 8)));
  95
  96
  97     return (int)data[0];
  98 } /* dtt_read() */
  99
 100
 101 int dtt_write(int sensor, int reg, int val)
 102 {
 103     int dlen;
 104     uchar data[2];
 105
 106     /*
 107      * Validate 'reg' param
 108      */
 109     if ((reg < 0) || (reg > 3))
 110         return 1;
 111
 112     /*
 113      * Calculate sensor address and register.
 114      */
 115     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* calculate address of lm75 */
 116
 117     /*
 118      * Handle 2 byte values.
 119      */
 120     if ((reg == DTT_READ_TEMP) ||
 121         (reg == DTT_TEMP_HYST) ||
 122         (reg == DTT_TEMP_SET)) {
 123         dlen = 2;
 124         data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
 125         data[1] = (char)(val & 0xff);
 126     } else {
 127         dlen = 1;
 128         data[0] = (char)(val & 0xff);
 129     }
 130
 131     /*
 132      * Write value to register.
 133      */
 134     if (i2c_write(sensor, reg, 1, data, dlen) != 0)
 135         return 1;
 136
 137     return 0;
 138 } /* dtt_write() */
 139
 140
 141 static int _dtt_init(int sensor)
 142 {
 143     int val;
 144
 145     /*
 146      * Setup TSET ( trip point ) register
 147      */
 148     val = ((CFG_DTT_MAX_TEMP * 2) << 7) & 0xff80; /* trip */
 149     if (dtt_write(sensor, DTT_TEMP_SET, val) != 0)
 150         return 1;
 151
 152     /*
 153      * Setup THYST ( untrip point ) register - Hysteresis
 154      */
 155     val = (((CFG_DTT_MAX_TEMP - CFG_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 156     if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
 157         return 1;
 158
 159     /*
 160      * Setup configuraton register
 161      */
 162 #ifdef CONFIG_DTT_AD7414
 163     /* config = alert active low and disabled */
 164     val = 0x60;
 165 #else
 166     /* config = 6 sample integration, int mode, active low, and enable */
 167     val = 0x18;
 168 #endif
 169     if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 170         return 1;
 171
 172     return 0;
 173 } /* _dtt_init() */
 174
 175
 176 int dtt_init (void)
 177 {
 178     int i;
 179     unsigned char sensors[] = CONFIG_DTT_SENSORS;
 180     const char *const header = "DTT:   ";
 181
 182     for (i = 0; i < sizeof(sensors); i++) {
 183         if (_dtt_init(sensors[i]) != 0)
 184             printf("%s%d FAILED INIT\n", header, i+1);
 185         else
 186             printf("%s%d is %i C\n", header, i+1,
 187                    dtt_get_temp(sensors[i]));
 188     }
 189
 190     return (0);
 191 } /* dtt_init() */
 192
 193 int dtt_get_temp(int sensor)
 194 {
 195     int const ret = dtt_read(sensor, DTT_READ_TEMP);
 196
 197     if (ret < 0) {
 198         printf("DTT temperature read failed.\n");
 199         return 0;
 200     }
 201     return (int)((int16_t) ret / 256);
 202 } /* dtt_get_temp() */
 203
 204 #endif /* CONFIG_DTT_LM75 */