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
  30 #ifdef CONFIG_DTT_DS1621
  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_DS1621"
  34 #endif
  35 #include <i2c.h>
  36 #include <dtt.h>
  37
  38 /*
  39  * Device code
  40  */
  41 #define DTT_I2C_DEV_CODE 0x48                   /* Dallas Semi's DS1621 */
  42
  43 int dtt_read(int sensor, int reg)
  44 {
  45     int dlen;
  46     uchar data[2];
  47
  48     /*
  49      * Calculate sensor address and command.
  50      *
  51      */
  52     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1621*/
  53
  54     /*
  55      * Prepare to handle 2 byte result.
  56      */
  57     if ((reg == DTT_READ_TEMP) ||
  58         (reg == DTT_TEMP_HIGH) || (reg == DTT_TEMP_LOW))
  59         dlen = 2;
  60     else
  61         dlen = 1;
  62
  63     /*
  64      * Now try to read the register.
  65      */
  66     if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  67         return 1;
  68
  69     /*
  70      * Handle 2 byte result.
  71      */
  72     if (dlen == 2)
  73         return ((int)((short)data[1] + (((short)data[0]) << 8)));
  74
  75     return (int)data[0];
  76 } /* dtt_read() */
  77
  78
  79 int dtt_write(int sensor, int reg, int val)
  80 {
  81     int dlen;
  82     uchar data[2];
  83
  84     /*
  85      * Calculate sensor address and register.
  86      *
  87      */
  88     sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  89
  90     /*
  91      * Handle various data sizes.
  92      */
  93     if ((reg == DTT_READ_TEMP) ||
  94         (reg == DTT_TEMP_HIGH) || (reg == DTT_TEMP_LOW)) {
  95         dlen = 2;
  96         data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
  97         data[1] = (char)(val & 0xff);
  98     }
  99     else if ((reg == DTT_WRITE_START_CONV) || (reg == DTT_WRITE_STOP_CONV)) {
 100         dlen = 0;
 101         data[0] = (char)0;
 102         data[1] = (char)0;
 103     }
 104     else {
 105         dlen = 1;
 106         data[0] = (char)(val & 0xff);
 107     }
 108
 109     /*
 110      * Write value to device.
 111      */
 112     if (i2c_write(sensor, reg, 1, data, dlen) != 0)
 113         return 1;
 114
 115     return 0;
 116 } /* dtt_write() */
 117
 118
 119 static int _dtt_init(int sensor)
 120 {
 121     int val;
 122
 123     /*
 124      * Setup High Temp.
 125      */
 126     val = ((CFG_DTT_MAX_TEMP * 2) << 7) & 0xff80;
 127     if (dtt_write(sensor, DTT_TEMP_HIGH, val) != 0)
 128         return 1;
 129     udelay(50000);                              /* Max 50ms */
 130
 131     /*
 132      * Setup Low Temp - hysteresis.
 133      */
 134     val = (((CFG_DTT_MAX_TEMP - CFG_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 135     if (dtt_write(sensor, DTT_TEMP_LOW, val) != 0)
 136         return 1;
 137     udelay(50000);                              /* Max 50ms */
 138
 139     /*
 140      * Setup configuraton register
 141      *
 142      * Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES
 143      *
 144      * We run in polled mode, since there isn't any way to know if this
 145      * lousy device is ready to provide temperature readings on power up.
 146      */
 147     val = 0x9;
 148     if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 149         return 1;
 150     udelay(50000);                              /* Max 50ms */
 151
 152     return 0;
 153 } /* _dtt_init() */
 154
 155
 156 int dtt_init (void)
 157 {
 158     int i;
 159     unsigned char sensors[] = CONFIG_DTT_SENSORS;
 160
 161     for (i = 0; i < sizeof(sensors); i++) {
 162         if (_dtt_init(sensors[i]) != 0)
 163             printf("DTT%d:  FAILED\n", i+1);
 164         else
 165             printf("DTT%d:  %i C\n", i+1, dtt_get_temp(sensors[i]));
 166     }
 167
 168     return (0);
 169 } /* dtt_init() */
 170
 171
 172 int dtt_get_temp(int sensor)
 173 {
 174     int i;
 175
 176     /*
 177      * Start a conversion, may take up to 1 second.
 178      */
 179     dtt_write(sensor, DTT_WRITE_START_CONV, 0);
 180     for (i = 0; i <= 10; i++) {
 181         udelay(100000);
 182         if (dtt_read(sensor, DTT_CONFIG) & 0x80)
 183             break;
 184     }
 185
 186     return (dtt_read(sensor, DTT_READ_TEMP) / 256);
 187 } /* dtt_get_temp() */
 188
 189
 190 #endif /* CONFIG_DTT_DS1621 */