firmware/target/arm/imx31/gigabeat-s/powermgmt-imx31.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2002 by Heikki Hannikainen, Uwe Freese
  11  * Revisions copyright (C) 2005 by Gerald Van Baren
  12  *
  13  * All files in this archive are subject to the GNU General Public License.
  14  * See the file COPYING in the source tree root for full license agreement.
  15  *
  16  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  17  * KIND, either express or implied.
  18  *
  19  ****************************************************************************/
  20
  21 /* FIXME: This is just the Gigabeat F/X file with a different name... */
  22
  23 #include "config.h"
  24 #include "adc.h"
  25 #include "powermgmt.h"
  26
  27 /**
  28  * Fixed-point natural log
  29  * taken from http://www.quinapalus.com/efunc.html
  30  *  "The code assumes integers are at least 32 bits long. The (positive)
  31  *   argument and the result of the function are both expressed as fixed-point
  32  *   values with 16 fractional bits, although intermediates are kept with 28
  33  *   bits of precision to avoid loss of accuracy during shifts."
  34  */
  35 static long flog(int x)
  36 {
  37     long t,y;
  38
  39     y=0xa65af;
  40     if(x<0x00008000) x<<=16,              y-=0xb1721;
  41     if(x<0x00800000) x<<= 8,              y-=0x58b91;
  42     if(x<0x08000000) x<<= 4,              y-=0x2c5c8;
  43     if(x<0x20000000) x<<= 2,              y-=0x162e4;
  44     if(x<0x40000000) x<<= 1,              y-=0x0b172;
  45     t=x+(x>>1); if((t&0x80000000)==0) x=t,y-=0x067cd;
  46     t=x+(x>>2); if((t&0x80000000)==0) x=t,y-=0x03920;
  47     t=x+(x>>3); if((t&0x80000000)==0) x=t,y-=0x01e27;
  48     t=x+(x>>4); if((t&0x80000000)==0) x=t,y-=0x00f85;
  49     t=x+(x>>5); if((t&0x80000000)==0) x=t,y-=0x007e1;
  50     t=x+(x>>6); if((t&0x80000000)==0) x=t,y-=0x003f8;
  51     t=x+(x>>7); if((t&0x80000000)==0) x=t,y-=0x001fe;
  52     x=0x80000000-x;
  53     y-=x>>15;
  54     return y;
  55 }
  56
  57
  58 const unsigned short battery_level_dangerous[BATTERY_TYPES_COUNT] =
  59 {
  60     3450
  61 };
  62
  63 const unsigned short battery_level_shutoff[BATTERY_TYPES_COUNT] =
  64 {
  65     3400
  66 };
  67
  68 /* voltages (millivolt) of 0%, 10%, ... 100% when charging disabled */
  69 const unsigned short percent_to_volt_discharge[BATTERY_TYPES_COUNT][11] =
  70 {
  71     /* Toshiba Gigabeat Li Ion 830mAH figured from discharge curve */
  72     { 3480, 3550, 3590, 3610, 3630, 3650, 3700, 3760, 3800, 3910, 3990 },
  73 };
  74
  75 /* voltages (millivolt) of 0%, 10%, ... 100% when charging enabled */
  76 const unsigned short percent_to_volt_charge[11] =
  77 {
  78     /* Toshiba Gigabeat Li Ion 830mAH */
  79     3480, 3550, 3590, 3610, 3630, 3650, 3700, 3760, 3800, 3910, 3990
  80 };
  81
  82 /* Returns battery voltage from ADC [millivolts] */
  83 unsigned int battery_adc_voltage(void)
  84 {
  85     /* ADC reading 0-1023 = 2400mV-4700mV */
  86     return ((adc_read(ADC_BATTERY) * 2303) >> 10) + 2400;
  87 }
  88
  89 /* Returns battery charge current from ADC [milliamps] */
  90 int battery_adc_charge_current(void)
  91 {
  92     /* Positive reading = charger to battery
  93      * Negative reading = battery to charger terminal
  94      * ADC reading -512-511 = -2875mA-2875mA */
  95     unsigned int value = adc_read(ADC_CHARGER_CURRENT);
  96     return (((int)value << 22) >> 22) * 2881 >> 9;
  97 }
  98
  99 /* Returns battery temperature from ADC [deg-C] */
 100 unsigned int battery_adc_temp(void)
 101 {
 102     unsigned int value = adc_read(ADC_BATTERY_TEMP);
 103     /* E[volts] = value * 2.3V / 1023
 104      * R[ohms] = E/I = E[volts] / 0.00002[A] (Thermistor bias current source)
 105      *
 106      * Steinhart-Hart thermistor equation (sans "C*ln^2(R)" term because it
 107      * has negligible effect):
 108      * [A + B*ln(R) + D*ln^3(R)] = 1 / T[°K]
 109      *
 110      * Coeffients that fit experimental data (one thermistor so far, one run):
 111      * A = 0.0013002631685462800
 112      * B = 0.0002000841932612330
 113      * D = 0.0000000640446750919
 114      *
 115      * Fixed-point output matches the floating-point version for each ADC
 116      * value.
 117      */
 118      int R = 2070000 * value;
 119      long long ln = flog(R) + 83196;
 120      long long t0 = 425890304133ll;
 121      long long t1 = 1000000*ln;
 122      long long t3 = ln*ln*ln / 13418057;
 123      return ((32754211579494400ll / (t0 + t1 + t3)) - 27315) / 100;
 124 }