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 DS1621/1631 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 /*
  46  * Config register bits
  47  */
  48 #define DTT_CONFIG_1SHOT        0x01
  49 #define DTT_CONFIG_POLARITY     0x02
  50 #define DTT_CONFIG_R0           0x04    /* ds1631 only */
  51 #define DTT_CONFIG_R1           0x08    /* ds1631 only */
  52 #define DTT_CONFIG_NVB          0x10
  53 #define DTT_CONFIG_TLF          0x20
  54 #define DTT_CONFIG_THF          0x40
  55 #define DTT_CONFIG_DONE         0x80
  56
  57
  58 int dtt_read(int sensor, int reg)
  59 {
  60         int dlen;
  61         uchar data[2];
  62
  63         /* Calculate sensor address and command */
  64         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1621*/
  65
  66         /* Prepare to handle 2 byte result */
  67         switch(reg) {
  68         case DTT_READ_TEMP:
  69         case DTT_TEMP_HIGH:
  70         case DTT_TEMP_LOW:
  71                 dlen = 2;
  72                 break;
  73         default:
  74                 dlen = 1;
  75         }
  76
  77         /* Now try to read the register */
  78         if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  79                 return 1;
  80
  81         /* Handle 2 byte result */
  82         if (dlen == 2)
  83                 return (short)((data[0] << 8) | data[1]);
  84
  85         return (int)data[0];
  86 }
  87
  88
  89 int dtt_write(int sensor, int reg, int val)
  90 {
  91         int dlen;
  92         uchar data[2];
  93
  94         /* Calculate sensor address and register */
  95         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  96
  97         /* Handle various data sizes. */
  98         switch(reg) {
  99         case DTT_READ_TEMP:
 100         case DTT_TEMP_HIGH:
 101         case DTT_TEMP_LOW:
 102                 dlen = 2;
 103                 data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
 104                 data[1] = (char)(val & 0xff);
 105                 break;
 106         case DTT_WRITE_START_CONV:
 107         case DTT_WRITE_STOP_CONV:
 108                 dlen = 0;
 109                 data[0] = (char)0;
 110                 data[1] = (char)0;
 111                 break;
 112         default:
 113                 dlen = 1;
 114                 data[0] = (char)(val & 0xff);
 115         }
 116
 117         /* Write value to device */
 118         if (i2c_write(sensor, reg, 1, data, dlen) != 0)
 119                 return 1;
 120
 121         /* Poll NV memory busy bit in case write was to register stored in EEPROM */
 122         while(i2c_reg_read(sensor, DTT_CONFIG) & DTT_CONFIG_NVB)
 123                 ;
 124
 125         return 0;
 126 }
 127
 128
 129 static int _dtt_init(int sensor)
 130 {
 131         int val;
 132
 133         /* Setup High Temp */
 134         val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80;
 135         if (dtt_write(sensor, DTT_TEMP_HIGH, val) != 0)
 136                 return 1;
 137
 138         /* Setup Low Temp - hysteresis */
 139         val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 140         if (dtt_write(sensor, DTT_TEMP_LOW, val) != 0)
 141                 return 1;
 142
 143         /*
 144          * Setup configuraton register
 145          *
 146          * Clear THF & TLF, Reserved = 1, Polarity = Active Low, One Shot = YES
 147          *
 148          * We run in polled mode, since there isn't any way to know if this
 149          * lousy device is ready to provide temperature readings on power up.
 150          */
 151         val = 0x9;
 152         if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 153                 return 1;
 154
 155         return 0;
 156 }
 157
 158
 159 int dtt_init (void)
 160 {
 161         int i;
 162         unsigned char sensors[] = CONFIG_DTT_SENSORS;
 163
 164         for (i = 0; i < sizeof(sensors); i++) {
 165                 if (_dtt_init(sensors[i]) != 0)
 166                         printf("DTT%d:  FAILED\n", i + 1);
 167                 else
 168                         printf("DTT%d:  %i C\n", i + 1, dtt_get_temp(sensors[i]));
 169         }
 170
 171         return (0);
 172 }
 173
 174
 175 int dtt_get_temp(int sensor)
 176 {
 177         int i;
 178
 179         /* Start a conversion, may take up to 1 second. */
 180         dtt_write(sensor, DTT_WRITE_START_CONV, 0);
 181         for (i = 0; i <= 10; i++) {
 182                 udelay(100000);
 183                 if (dtt_read(sensor, DTT_CONFIG) & DTT_CONFIG_DONE)
 184                         break;
 185         }
 186
 187         return (dtt_read(sensor, DTT_READ_TEMP) / 256);
 188 }