drivers/hwmon/ds1775.c

   1 /*
   2  * This program is free software; you can redistribute it and/or
   3  * modify it under the terms of the GNU General Public License as
   4  * published by the Free Software Foundation; either version 2 of
   5  * the License, or (at your option) any later version.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program; if not, write to the Free Software
  14  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  15  * MA 02111-1307 USA
  16  */
  17
  18 /*
  19  * Dallas Semiconductor's DS1775 Digital Thermometer and Thermostat
  20  */
  21
  22 #include <common.h>
  23
  24 #ifdef CONFIG_DTT_DS1775
  25 #include <i2c.h>
  26 #include <dtt.h>
  27
  28 #define DTT_I2C_DEV_CODE        CFG_I2C_DTT_ADDR /* Dallas Semi's DS1775 device code */
  29
  30 int dtt_read(int sensor, int reg)
  31 {
  32         int dlen;
  33         uchar data[2];
  34
  35         /*
  36          * Calculate sensor address and command
  37          */
  38         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1775 */
  39
  40         /*
  41          * Prepare to handle 2 byte result
  42          */
  43         if ((reg == DTT_READ_TEMP) ||
  44             (reg == DTT_TEMP_OS) || (reg == DTT_TEMP_HYST))
  45                 dlen = 2;
  46         else
  47                 dlen = 1;
  48
  49         /*
  50          * Now try to read the register
  51          */
  52         if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  53                 return 1;
  54
  55         /*
  56          * Handle 2 byte result
  57          */
  58         if (dlen == 2)
  59                 return ((int)((short)data[1] + (((short)data[0]) << 8)));
  60
  61         return (int) data[0];
  62 }
  63
  64
  65 int dtt_write(int sensor, int reg, int val)
  66 {
  67         int dlen;
  68         uchar data[2];
  69
  70         /*
  71          * Calculate sensor address and register
  72          */
  73         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  74
  75         /*
  76          * Handle various data sizes
  77          */
  78         if ((reg == DTT_READ_TEMP) ||
  79             (reg == DTT_TEMP_OS) || (reg == DTT_TEMP_HYST)) {
  80                 dlen = 2;
  81                 data[0] = (char)((val >> 8) & 0xff); /* MSB first */
  82                 data[1] = (char)(val & 0xff);
  83         } else {
  84                 dlen = 1;
  85                 data[0] = (char)(val & 0xff);
  86         }
  87
  88         /*
  89          * Write value to device
  90          */
  91         if (i2c_write(sensor, reg, 1, data, dlen) != 0)
  92                 return 1;
  93
  94         return 0;
  95 }
  96
  97
  98 static int _dtt_init(int sensor)
  99 {
 100         int val;
 101
 102         /*
 103          * Setup High Temp
 104          */
 105         val = ((CFG_DTT_MAX_TEMP * 2) << 7) & 0xff80;
 106         if (dtt_write(sensor, DTT_TEMP_OS, val) != 0)
 107                 return 1;
 108         udelay(50000);                  /* Max 50ms */
 109
 110         /*
 111          * Setup Low Temp - hysteresis
 112          */
 113         val = (((CFG_DTT_MAX_TEMP - CFG_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 114         if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
 115                 return 1;
 116         udelay(50000);                  /* Max 50ms */
 117
 118         /*
 119          * Setup configuraton register
 120          *
 121          * Fault Tolerance limits 4, Thermometer resolution bits is 9,
 122          * Polarity = Active Low,continuous conversion mode, Thermostat
 123          * mode is interrupt mode
 124          */
 125         val = 0xa;
 126         if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 127                 return 1;
 128         udelay(50000);                  /* Max 50ms */
 129
 130         return 0;
 131 }
 132
 133
 134 int dtt_init (void)
 135 {
 136         int i;
 137         unsigned char sensors[] = CONFIG_DTT_SENSORS;
 138
 139         for (i = 0; i < sizeof(sensors); i++) {
 140                 if (_dtt_init(sensors[i]) != 0)
 141                         printf("DTT%d:  FAILED\n", i+1);
 142                 else
 143                         printf("DTT%d:  %i C\n", i+1, dtt_get_temp(sensors[i]));
 144         }
 145
 146         return (0);
 147 }
 148
 149
 150 int dtt_get_temp(int sensor)
 151 {
 152         return (dtt_read(sensor, DTT_READ_TEMP) / 256);
 153 }
 154
 155
 156 #endif /* CONFIG_DTT_DS1775 */