drivers/hwmon/ds1621.c

   1 /*
   2  * (C) Copyright 2001
   3  * Erik Theisen,  Wave 7 Optics, etheisen@mindspring.com.
   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  * Dallas Semiconductor's DS1621 Digital Thermometer and Thermostat.
  26  */
  27
  28 #include <common.h>
  29 #include <i2c.h>
  30 #include <dtt.h>
  31
  32 /*
  33  * Device code
  34  */
  35 #define DTT_I2C_DEV_CODE 0x48                   /* Dallas Semi's DS1621 */
  36 #define DTT_READ_TEMP           0xAA
  37 #define DTT_READ_COUNTER        0xA8
  38 #define DTT_READ_SLOPE          0xA9
  39 #define DTT_WRITE_START_CONV    0xEE
  40 #define DTT_WRITE_STOP_CONV     0x22
  41 #define DTT_TEMP_HIGH           0xA1
  42 #define DTT_TEMP_LOW            0xA2
  43 #define DTT_CONFIG              0xAC
  44
  45 int dtt_read(int sensor, int reg)
  46 {
  47     int dlen;
  48     uchar data[2];
  49
  50     /*
  51      * Calculate sensor address and command.
  52      *
  53      */
  54     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1621*/
  55
  56     /*
  57      * Prepare to handle 2 byte result.
  58      */
  59     if ((reg == DTT_READ_TEMP) ||
  60         (reg == DTT_TEMP_HIGH) || (reg == DTT_TEMP_LOW))
  61         dlen = 2;
  62     else
  63         dlen = 1;
  64
  65     /*
  66      * Now try to read the register.
  67      */
  68     if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  69         return 1;
  70
  71     /*
  72      * Handle 2 byte result.
  73      */
  74     if (dlen == 2)
  75         return ((int)((short)data[1] + (((short)data[0]) << 8)));
  76
  77     return (int)data[0];
  78 } /* dtt_read() */
  79
  80
  81 int dtt_write(int sensor, int reg, int val)
  82 {
  83     int dlen;
  84     uchar data[2];
  85
  86     /*
  87      * Calculate sensor address and register.
  88      *
  89      */
  90     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  91
  92     /*
  93      * Handle various data sizes.
  94      */
  95     if ((reg == DTT_READ_TEMP) ||
  96         (reg == DTT_TEMP_HIGH) || (reg == DTT_TEMP_LOW)) {
  97         dlen = 2;
  98         data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
  99         data[1] = (char)(val & 0xff);
 100     }
 101     else if ((reg == DTT_WRITE_START_CONV) || (reg == DTT_WRITE_STOP_CONV)) {
 102         dlen = 0;
 103         data[0] = (char)0;
 104         data[1] = (char)0;
 105     }
 106     else {
 107         dlen = 1;
 108         data[0] = (char)(val & 0xff);
 109     }
 110
 111     /*
 112      * Write value to device.
 113      */
 114     if (i2c_write(sensor, reg, 1, data, dlen) != 0)
 115         return 1;
 116
 117     return 0;
 118 } /* dtt_write() */
 119
 120
 121 static int _dtt_init(int sensor)
 122 {
 123     int val;
 124
 125     /*
 126      * Setup High Temp.
 127      */
 128     val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80;
 129     if (dtt_write(sensor, DTT_TEMP_HIGH, val) != 0)
 130         return 1;
 131     udelay(50000);                              /* Max 50ms */
 132
 133     /*
 134      * Setup Low Temp - hysteresis.
 135      */
 136     val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 137     if (dtt_write(sensor, DTT_TEMP_LOW, val) != 0)
 138         return 1;
 139     udelay(50000);                              /* Max 50ms */
 140
 141     /*
 142      * Setup configuraton register
 143      *
 144      * Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES
 145      *
 146      * We run in polled mode, since there isn't any way to know if this
 147      * lousy device is ready to provide temperature readings on power up.
 148      */
 149     val = 0x9;
 150     if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 151         return 1;
 152     udelay(50000);                              /* Max 50ms */
 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
 163     for (i = 0; i < sizeof(sensors); i++) {
 164         if (_dtt_init(sensors[i]) != 0)
 165             printf("DTT%d:  FAILED\n", i+1);
 166         else
 167             printf("DTT%d:  %i C\n", i+1, dtt_get_temp(sensors[i]));
 168     }
 169
 170     return (0);
 171 } /* dtt_init() */
 172
 173
 174 int dtt_get_temp(int sensor)
 175 {
 176     int i;
 177
 178     /*
 179      * Start a conversion, may take up to 1 second.
 180      */
 181     dtt_write(sensor, DTT_WRITE_START_CONV, 0);
 182     for (i = 0; i <= 10; i++) {
 183         udelay(100000);
 184         if (dtt_read(sensor, DTT_CONFIG) & 0x80)
 185             break;
 186     }
 187
 188     return (dtt_read(sensor, DTT_READ_TEMP) / 256);
 189 } /* dtt_get_temp() */