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 #if defined(CFG_I2C_DTT_ADDR)
  42 #define DTT_I2C_DEV_CODE CFG_I2C_DTT_ADDR
  43 #else
  44 #define DTT_I2C_DEV_CODE 0x48                   /* ON Semi's LM75 device */
  45 #endif
  46 #define DTT_READ_TEMP           0x0
  47 #define DTT_CONFIG              0x1
  48 #define DTT_TEMP_HYST           0x2
  49 #define DTT_TEMP_SET            0x3
  50
  51 int dtt_read(int sensor, int reg)
  52 {
  53     int dlen;
  54     uchar data[2];
  55
  56 #ifdef CONFIG_DTT_AD7414
  57     /*
  58      * On AD7414 the first value upon bootup is not read correctly.
  59      * This is most likely because of the 800ms update time of the
  60      * temp register in normal update mode. To get current values
  61      * each time we issue the "dtt" command including upon powerup
  62      * we switch into one-short mode.
  63      *
  64      * Issue one-shot mode command
  65      */
  66     dtt_write(sensor, DTT_CONFIG, 0x64);
  67 #endif
  68
  69     /*
  70      * Validate 'reg' param
  71      */
  72     if((reg < 0) || (reg > 3))
  73         return -1;
  74
  75     /*
  76      * Calculate sensor address and register.
  77      */
  78     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* calculate address of lm75 */
  79
  80     /*
  81      * Prepare to handle 2 byte result.
  82      */
  83     if ((reg == DTT_READ_TEMP) ||
  84         (reg == DTT_TEMP_HYST) ||
  85         (reg == DTT_TEMP_SET))
  86         dlen = 2;
  87     else
  88         dlen = 1;
  89
  90     /*
  91      * Now try to read the register.
  92      */
  93     if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  94         return -1;
  95
  96     /*
  97      * Handle 2 byte result.
  98      */
  99     if (dlen == 2)
 100         return ((int)((short)data[1] + (((short)data[0]) << 8)));
 101
 102
 103     return (int)data[0];
 104 } /* dtt_read() */
 105
 106
 107 int dtt_write(int sensor, int reg, int val)
 108 {
 109     int dlen;
 110     uchar data[2];
 111
 112     /*
 113      * Validate 'reg' param
 114      */
 115     if ((reg < 0) || (reg > 3))
 116         return 1;
 117
 118     /*
 119      * Calculate sensor address and register.
 120      */
 121     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* calculate address of lm75 */
 122
 123     /*
 124      * Handle 2 byte values.
 125      */
 126     if ((reg == DTT_READ_TEMP) ||
 127         (reg == DTT_TEMP_HYST) ||
 128         (reg == DTT_TEMP_SET)) {
 129         dlen = 2;
 130         data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
 131         data[1] = (char)(val & 0xff);
 132     } else {
 133         dlen = 1;
 134         data[0] = (char)(val & 0xff);
 135     }
 136
 137     /*
 138      * Write value to register.
 139      */
 140     if (i2c_write(sensor, reg, 1, data, dlen) != 0)
 141         return 1;
 142
 143     return 0;
 144 } /* dtt_write() */
 145
 146
 147 static int _dtt_init(int sensor)
 148 {
 149     int val;
 150
 151     /*
 152      * Setup TSET ( trip point ) register
 153      */
 154     val = ((CFG_DTT_MAX_TEMP * 2) << 7) & 0xff80; /* trip */
 155     if (dtt_write(sensor, DTT_TEMP_SET, val) != 0)
 156         return 1;
 157
 158     /*
 159      * Setup THYST ( untrip point ) register - Hysteresis
 160      */
 161     val = (((CFG_DTT_MAX_TEMP - CFG_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 162     if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
 163         return 1;
 164
 165     /*
 166      * Setup configuraton register
 167      */
 168 #ifdef CONFIG_DTT_AD7414
 169     /* config = alert active low and disabled */
 170     val = 0x60;
 171 #else
 172     /* config = 6 sample integration, int mode, active low, and enable */
 173     val = 0x18;
 174 #endif
 175     if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 176         return 1;
 177
 178     return 0;
 179 } /* _dtt_init() */
 180
 181
 182 int dtt_init (void)
 183 {
 184     int i;
 185     unsigned char sensors[] = CONFIG_DTT_SENSORS;
 186     const char *const header = "DTT:   ";
 187
 188     for (i = 0; i < sizeof(sensors); i++) {
 189         if (_dtt_init(sensors[i]) != 0)
 190             printf("%s%d FAILED INIT\n", header, i+1);
 191         else
 192             printf("%s%d is %i C\n", header, i+1,
 193                    dtt_get_temp(sensors[i]));
 194     }
 195
 196     return (0);
 197 } /* dtt_init() */
 198
 199 int dtt_get_temp(int sensor)
 200 {
 201     int const ret = dtt_read(sensor, DTT_READ_TEMP);
 202
 203     if (ret < 0) {
 204         printf("DTT temperature read failed.\n");
 205         return 0;
 206     }
 207     return (int)((int16_t) ret / 256);
 208 } /* dtt_get_temp() */