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 #include <i2c.h>
  30 #include <dtt.h>
  31
  32 /*
  33  * Device code
  34  */
  35 #if defined(CFG_I2C_DTT_ADDR)
  36 #define DTT_I2C_DEV_CODE CFG_I2C_DTT_ADDR
  37 #else
  38 #define DTT_I2C_DEV_CODE 0x48                   /* ON Semi's LM75 device */
  39 #endif
  40 #define DTT_READ_TEMP           0x0
  41 #define DTT_CONFIG              0x1
  42 #define DTT_TEMP_HYST           0x2
  43 #define DTT_TEMP_SET            0x3
  44
  45 int dtt_read(int sensor, int reg)
  46 {
  47         int dlen;
  48         uchar data[2];
  49
  50 #ifdef CONFIG_DTT_AD7414
  51         /*
  52          * On AD7414 the first value upon bootup is not read correctly.
  53          * This is most likely because of the 800ms update time of the
  54          * temp register in normal update mode. To get current values
  55          * each time we issue the "dtt" command including upon powerup
  56          * we switch into one-short mode.
  57          *
  58          * Issue one-shot mode command
  59          */
  60         dtt_write(sensor, DTT_CONFIG, 0x64);
  61 #endif
  62
  63         /* Validate 'reg' param */
  64         if((reg < 0) || (reg > 3))
  65                 return -1;
  66
  67         /* Calculate sensor address and register. */
  68         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
  69
  70         /* Prepare to handle 2 byte result. */
  71         if ((reg == DTT_READ_TEMP) ||
  72                 (reg == DTT_TEMP_HYST) ||
  73                 (reg == DTT_TEMP_SET))
  74                         dlen = 2;
  75         else
  76                 dlen = 1;
  77
  78         /* Now try to read the register. */
  79         if (i2c_read(sensor, reg, 1, data, dlen) != 0)
  80                 return -1;
  81
  82         /* Handle 2 byte result. */
  83         if (dlen == 2)
  84                 return ((int)((short)data[1] + (((short)data[0]) << 8)));
  85
  86         return (int)data[0];
  87 } /* dtt_read() */
  88
  89
  90 int dtt_write(int sensor, int reg, int val)
  91 {
  92         int dlen;
  93         uchar data[2];
  94
  95         /* Validate 'reg' param */
  96         if ((reg < 0) || (reg > 3))
  97                 return 1;
  98
  99         /* Calculate sensor address and register. */
 100         sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
 101
 102         /* Handle 2 byte values. */
 103         if ((reg == DTT_READ_TEMP) ||
 104                 (reg == DTT_TEMP_HYST) ||
 105                 (reg == DTT_TEMP_SET)) {
 106                         dlen = 2;
 107                 data[0] = (char)((val >> 8) & 0xff);    /* MSB first */
 108                 data[1] = (char)(val & 0xff);
 109         } else {
 110                 dlen = 1;
 111                 data[0] = (char)(val & 0xff);
 112         }
 113
 114         /* Write value to register. */
 115         if (i2c_write(sensor, reg, 1, data, dlen) != 0)
 116                 return 1;
 117
 118         return 0;
 119 } /* dtt_write() */
 120
 121
 122 static int _dtt_init(int sensor)
 123 {
 124         int val;
 125
 126         /* Setup TSET ( trip point ) register */
 127         val = ((CFG_DTT_MAX_TEMP * 2) << 7) & 0xff80; /* trip */
 128         if (dtt_write(sensor, DTT_TEMP_SET, val) != 0)
 129                 return 1;
 130
 131         /* Setup THYST ( untrip point ) register - Hysteresis */
 132         val = (((CFG_DTT_MAX_TEMP - CFG_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
 133         if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
 134                 return 1;
 135
 136         /* Setup configuraton register */
 137 #ifdef CONFIG_DTT_AD7414
 138         /* config = alert active low and disabled */
 139         val = 0x60;
 140 #else
 141         /* config = 6 sample integration, int mode, active low, and enable */
 142         val = 0x18;
 143 #endif
 144         if (dtt_write(sensor, DTT_CONFIG, val) != 0)
 145                 return 1;
 146
 147         return 0;
 148 } /* _dtt_init() */
 149
 150
 151 int dtt_init (void)
 152 {
 153         int i;
 154         unsigned char sensors[] = CONFIG_DTT_SENSORS;
 155         const char *const header = "DTT:   ";
 156         int old_bus;
 157
 158         /* switch to correct I2C bus */
 159         old_bus = I2C_GET_BUS();
 160         I2C_SET_BUS(CFG_DTT_BUS_NUM);
 161
 162         for (i = 0; i < sizeof(sensors); i++) {
 163         if (_dtt_init(sensors[i]) != 0)
 164                 printf("%s%d FAILED INIT\n", header, i+1);
 165         else
 166                 printf("%s%d is %i C\n", header, i+1,
 167                 dtt_get_temp(sensors[i]));
 168         }
 169         /* switch back to original I2C bus */
 170         I2C_SET_BUS(old_bus);
 171
 172         return (0);
 173 } /* dtt_init() */
 174
 175 int dtt_get_temp(int sensor)
 176 {
 177         int const ret = dtt_read(sensor, DTT_READ_TEMP);
 178
 179         if (ret < 0) {
 180                 printf("DTT temperature read failed.\n");
 181                 return 0;
 182         }
 183         return (int)((int16_t) ret / 256);
 184 } /* dtt_get_temp() */