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) 2008 by Michael Sevakis
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include <stdlib.h>
  22 #include "config.h"
  23 #include "system.h"
  24 #include "thread.h"
  25 #include "mc13783.h"
  26 #include "adc.h"
  27 #include "powermgmt.h"
  28 #include "power.h"
  29 #include "power-imx31.h"
  30
  31 /* TODO: Battery tests to get the right values! */
  32 const unsigned short battery_level_dangerous[BATTERY_TYPES_COUNT] =
  33 {
  34     3450
  35 };
  36
  37 const unsigned short battery_level_shutoff[BATTERY_TYPES_COUNT] =
  38 {
  39     3400
  40 };
  41
  42 /* voltages (millivolt) of 0%, 10%, ... 100% when charging disabled */
  43 const unsigned short percent_to_volt_discharge[BATTERY_TYPES_COUNT][11] =
  44 {
  45     /* Toshiba Gigabeat Li Ion 830mAH figured from discharge curve */
  46     { 3480, 3550, 3590, 3610, 3630, 3650, 3700, 3760, 3800, 3910, 3990 },
  47 };
  48
  49 /* voltages (millivolt) of 0%, 10%, ... 100% when charging enabled */
  50 const unsigned short percent_to_volt_charge[11] =
  51 {
  52     /* Toshiba Gigabeat Li Ion 830mAH */
  53     3480, 3550, 3590, 3610, 3630, 3650, 3700, 3760, 3800, 3910, 3990
  54 };
  55
  56 /* Returns battery voltage from ADC [millivolts] */
  57 unsigned int battery_adc_voltage(void)
  58 {
  59     /* ADC reading 0-1023 = 2400mV-4700mV */
  60     return ((adc_read(ADC_BATTERY) * 2303) >> 10) + 2400;
  61 }
  62
  63 /* Returns the application supply voltage from ADC [millvolts] */
  64 unsigned int application_supply_adc_voltage(void)
  65 {
  66     return ((adc_read(ADC_APPLICATION_SUPPLY) * 2303) >> 10) + 2400;
  67 }
  68
  69 unsigned int chrgraw_adc_voltage(void)
  70 {
  71     return (adc_read(ADC_CHARGER_VOLTAGE) * 23023) >> 10;
  72 }
  73
  74 /* Returns battery charge current from ADC [milliamps] */
  75 int battery_adc_charge_current(void)
  76 {
  77     /* Positive reading = charger to battery
  78      * Negative reading = battery to charger terminal
  79      * ADC reading -512-511 = -2875mA-2875mA */
  80     unsigned int value = adc_read(ADC_CHARGER_CURRENT);
  81     int I;
  82
  83     if (value == ADC_READ_ERROR)
  84         return INT_MIN;
  85
  86     I = ((((int32_t)value << 22) >> 22) * 2881) >> 9;
  87     return ILEVEL_ADJUST_IN(I);
  88 }
  89
  90 /* Estimate power dissipation in the charge path regulator in mW. */
  91 unsigned int cccv_regulator_dissipation(void)
  92 {
  93     /* BATTISNS is shorted to BATT so we don't need to use the
  94      * battery current reading. */
  95     int chrgraw = (adc_read(ADC_CHARGER_VOLTAGE) * 230225) >> 10;
  96     int batt = ((adc_read(ADC_BATTERY) * 23023) >> 10) + 24000;
  97     int ichrgsn = adc_read(ADC_CHARGER_CURRENT);
  98     ichrgsn = ((((int32_t)ichrgsn << 22) >> 22) * 2881) >> 9;
  99     ichrgsn = abs(ichrgsn);
 100
 101     return (chrgraw - ichrgsn - batt)*ILEVEL_ADJUST_IN(ichrgsn) / 10000;
 102 }
 103
 104 /* Returns battery temperature from ADC [deg-C] */
 105 int battery_adc_temp(void)
 106 {
 107     /* E[volts] = value * 2.3V / 1023
 108      * R[ohms] = E/I = E[volts] / 0.00002[A] (Thermistor bias current source)
 109      *
 110      * Steinhart-Hart thermistor equation:
 111      * [A + B*ln(R) + D*ln^3(R)] = 1 / T[°K]
 112      *
 113      * Coeffients that fit experimental data (one thermistor so far, one run):
 114      * A = 0.0013002631685462800
 115      * B = 0.0002000841932612330
 116      * D = 0.0000000640446750919
 117      */
 118     static const unsigned short ntc_table[] =
 119     {
 120 #if 0   /* These have degree deltas > 1  (except the final two) so leave them
 121          * out. 70 deg C upper limit is quite sufficient. */
 122            0, /* INF */   1, /* 171 */   2, /* 145 */   3, /* 130 */
 123            4, /* 121 */   5, /* 114 */   6, /* 108 */   7, /* 104 */
 124            8, /* 100 */   9, /*  96 */  10, /*  93 */  11, /*  91 */
 125           12, /*  88 */  13, /*  86 */  14, /*  84 */  15, /*  82 */
 126           16, /*  81 */  17, /*  79 */  18, /*  78 */  19, /*  76 */
 127           20, /*  75 */  21, /*  74 */  22, /*  72 */  23, /*  71 */
 128 #endif
 129           24, /*  70 */  25, /*  69 */  26, /*  68 */  27, /*  67 */
 130           28, /*  66 */  30, /*  65 */  31, /*  64 */  32, /*  63 */
 131           33, /*  62 */  35, /*  61 */  36, /*  60 */  38, /*  59 */
 132           39, /*  58 */  41, /*  57 */  43, /*  56 */  45, /*  55 */
 133           47, /*  54 */  49, /*  53 */  51, /*  52 */  53, /*  51 */
 134           56, /*  50 */  58, /*  49 */  61, /*  48 */  63, /*  47 */
 135           66, /*  46 */  69, /*  45 */  73, /*  44 */  76, /*  43 */
 136           80, /*  42 */  83, /*  41 */  87, /*  40 */  92, /*  39 */
 137           96, /*  38 */ 101, /*  37 */ 106, /*  36 */ 111, /*  35 */
 138          116, /*  34 */ 122, /*  33 */ 128, /*  32 */ 135, /*  31 */
 139          142, /*  30 */ 149, /*  29 */ 156, /*  28 */ 164, /*  27 */
 140          173, /*  26 */ 182, /*  25 */ 192, /*  24 */ 202, /*  23 */
 141          212, /*  22 */ 224, /*  21 */ 236, /*  20 */ 249, /*  19 */
 142          262, /*  18 */ 277, /*  17 */ 292, /*  16 */ 308, /*  15 */
 143          325, /*  14 */ 344, /*  13 */ 363, /*  12 */ 384, /*  11 */
 144          406, /*  10 */ 429, /*   9 */ 454, /*   8 */ 480, /*   7 */
 145          509, /*   6 */ 539, /*   5 */ 571, /*   4 */ 605, /*   3 */
 146          641, /*   2 */ 680, /*   1 */ 722, /*   0 */ 766, /*  -1 */
 147          813, /*  -2 */ 864, /*  -3 */ 918, /*  -4 */ 976, /*  -5 */
 148     };
 149
 150     unsigned int value = adc_read(ADC_BATTERY_TEMP);
 151
 152     if (value > 0)
 153     {
 154         unsigned i;
 155
 156         for (i = 1; i < ARRAYLEN(ntc_table); i++)
 157         {
 158             if (ntc_table[i] > value)
 159                 break;
 160         }
 161
 162         return 71 - i;
 163     }
 164
 165     return INT_MIN;
 166 }
 167
 168 /** Charger control **/
 169
 170 /* All code has a preference for the main charger being connected over
 171  * USB. USB is considered in the algorithm only if it is the sole source. */
 172 static uint32_t int_sense0 = 0;      /* Interrupt Sense 0 bits */
 173 static unsigned int last_inputs = POWER_INPUT_NONE; /* Detect input changes */
 174 static int charger_total_timer = 0;  /* Total allowed charging time */
 175 static int icharger_ave = 0;         /* Filtered charging current */
 176 static bool charger_close = false;   /* Shutdown notification */
 177 static bool service_wdt = true;      /* Service the watchdog timer, if things
 178                                         go very wrong, cease and shut down. */
 179 static uint32_t charger_setting = 0; /* Current ICHRG and VCHRG regulator
 180                                       * setting (register bits) */
 181 #define CHARGER_ADJUST ((uint32_t)-1)/* Force change in regulator setting */
 182 static int autorecharge_counter = 0 ; /* Battery < threshold debounce */
 183 static int chgcurr_timer = 0;        /* Countdown to CHGCURR error */
 184 #define AUTORECHARGE_COUNTDOWN (10*2) /* 10s debounce */
 185 #define WATCHDOG_TIMEOUT       (10*2) /* If not serviced, poweroff in 10s */
 186 #define CHGCURR_TIMEOUT        (4*2)  /* 4s debounce */
 187
 188 /* Temperature monitoring */
 189 static enum
 190 {
 191     TEMP_STATE_NORMAL = 0, /* Within range */
 192     TEMP_STATE_WAIT = 1,   /* Went out of range, wait to come back */
 193     TEMP_LOW_LIMIT = 0,    /* Min temp */
 194     TEMP_HIGH_LIMIT = 1,   /* Max temp */
 195 } temp_state = TEMP_STATE_NORMAL;
 196
 197 /* Set power thread priority for charging mode or not */
 198 static inline void charging_set_thread_priority(bool charging)
 199 {
 200 #ifdef HAVE_PRIORITY_SCHEDULING
 201     thread_set_priority(THREAD_ID_CURRENT,
 202                         charging ? PRIORITY_REALTIME : PRIORITY_SYSTEM);
 203 #endif
 204     (void)charging;
 205 }
 206
 207 /* Update filtered charger current - exponential moving average */
 208 static bool charger_current_filter_step(void)
 209 {
 210     int value = battery_adc_charge_current();
 211
 212     if (value == ADC_READ_ERROR)
 213         return false;
 214
 215     icharger_ave += value - (icharger_ave / ICHARGER_AVE_SAMPLES);
 216     return true;
 217 }
 218
 219 /* Return true if the main charger is connected. */
 220 static bool main_charger_connected(void)
 221 {
 222     return (last_inputs &
 223             POWER_INPUT_MAIN_CHARGER &
 224             POWER_INPUT_CHARGER) != 0;
 225 }
 226
 227 /* Return the voltage level which should automatically trigger
 228  * another recharge cycle based upon which power source is available.
 229  * Assumes at least one is. */
 230 static unsigned int auto_recharge_voltage(void)
 231 {
 232     if (main_charger_connected())
 233         return BATT_VAUTO_RECHARGE;
 234     else
 235         return BATT_USB_VAUTO_RECHARGE;
 236 }
 237
 238 /* Return greater of supply (BP) or filtered battery voltage. */
 239 unsigned int input_millivolts(void)
 240 {
 241     unsigned int app_millivolts = application_supply_adc_voltage();
 242     unsigned int bat_millivolts = battery_voltage();
 243
 244     return MAX(app_millivolts, bat_millivolts);
 245 }
 246
 247 /* Get smoothed readings for initializing filtered data. */
 248 static int stat_battery_reading(int type)
 249 {
 250     int high = INT_MIN, low = INT_MAX;
 251     int value = 0;
 252     int i;
 253
 254     for (i = 0; i < 7; i++)
 255     {
 256         int reading = ADC_READ_ERROR;
 257
 258         sleep(2); /* Get unique readings */
 259
 260         switch (type)
 261         {
 262         case ADC_BATTERY:
 263             reading = battery_adc_voltage();
 264             break;
 265
 266         case ADC_CHARGER_CURRENT:
 267             reading = battery_adc_charge_current();
 268             break;
 269         }
 270
 271         if (reading == ADC_READ_ERROR)
 272             return INT_MIN;
 273
 274         if (reading > high)
 275             high = reading;
 276
 277         if (reading < low)
 278             low = reading;
 279
 280         value += reading;
 281     }
 282
 283     /* Discard extremes */
 284     return (value - high - low) / 5;
 285 }
 286
 287 /* Update filtered battery voltage instead of waiting for filter
 288  * decay. */
 289 static bool update_filtered_battery_voltage(void)
 290 {
 291     int millivolts = stat_battery_reading(ADC_BATTERY);
 292
 293     if (millivolts != INT_MIN)
 294     {
 295         reset_battery_filter(millivolts);
 296         return true;
 297     }
 298
 299     return false;
 300 }
 301
 302 /* Sets the charge current limit based upon state. charge_state should be
 303  * set before calling. */
 304 static bool adjust_charger_current(void)
 305 {
 306     static const uint8_t charger_bits[][2] =
 307     {
 308         [DISCHARGING] =
 309         {
 310             /* These are actually zeros but reflect this setting */
 311             MC13783_ICHRG_0MA | MC13783_VCHRG_4_050V,
 312             MC13783_ICHRG_0MA | MC13783_VCHRG_4_050V,
 313         },
 314         /* Main(+USB): Charge slowly from the adapter until voltage is
 315          * sufficient for normal charging.
 316          *
 317          * USB: The truth is that things will probably not make it this far.
 318          * Cover the case, just in case the disk isn't used and it is
 319          * manageable. */
 320         [TRICKLE] =
 321         {
 322             BATTERY_ITRICKLE | BATTERY_VCHARGING,
 323             BATTERY_ITRICKLE_USB | BATTERY_VCHARGING
 324         },
 325         [TOPOFF] =
 326         {
 327             BATTERY_IFAST | BATTERY_VCHARGING,
 328             BATTERY_IFAST_USB | BATTERY_VCHARGING
 329         },
 330         [CHARGING] =
 331         {
 332             BATTERY_IFAST | BATTERY_VCHARGING,
 333             BATTERY_IFAST_USB | BATTERY_VCHARGING
 334         },
 335         /* Must maintain battery when on USB power only - utterly nasty
 336          * but true and something retailos does (it will even end up charging
 337          * the battery but not reporting that it is doing so).
 338          * Float lower than MAX - could end up slightly discharging after
 339          * a full charge but this is safer than maxing it out. */
 340         [CHARGING+1] =
 341         {
 342             BATTERY_IFLOAT_USB | BATTERY_VFLOAT_USB,
 343             BATTERY_IMAINTAIN_USB | BATTERY_VMAINTAIN_USB
 344         },
 345 #if 0
 346         /* Slower settings to so that the linear regulator doesn't dissipate
 347          * an excessive amount of power when coming out of precharge state. */
 348         [CHARGING+2] =
 349         {
 350             BATTERY_ISLOW | BATTERY_VCHARGING,
 351             BATTERY_ISLOW_USB | BATTEYR_VCHARGING
 352         },
 353 #endif
 354     };
 355
 356     bool success = false;
 357     int usb_select;
 358     uint32_t i;
 359
 360     usb_select = ((last_inputs & POWER_INPUT) == POWER_INPUT_USB)
 361                     ? 1 : 0;
 362
 363     if (charge_state == DISCHARGING && usb_select == 1)
 364     {
 365         /* USB-only, DISCHARGING, = maintaining battery */
 366         int select = (last_inputs & POWER_INPUT_CHARGER) ? 0 : 1;
 367         charger_setting = charger_bits[CHARGING+1][select];
 368     }
 369     else
 370     {
 371         /* Take very good care not to write garbage. */
 372         int state = charge_state;
 373
 374         if (state < DISCHARGING || state > CHARGING)
 375             state = DISCHARGING;
 376
 377         charger_setting = charger_bits[state][usb_select];
 378     }
 379
 380     if (charger_setting != 0)
 381     {
 382         charging_set_thread_priority(true);
 383
 384         /* Turn regulator logically ON. Hardware may still override. */
 385         i = mc13783_write_masked(MC13783_CHARGER,
 386                                  charger_setting | MC13783_CHRGRAWPDEN,
 387                                  MC13783_ICHRG | MC13783_VCHRG |
 388                                  MC13783_CHRGRAWPDEN);
 389
 390         if (i != MC13783_DATA_ERROR)
 391         {
 392             int icharger;
 393
 394             /* Enable charge current conversion */
 395             adc_enable_channel(ADC_CHARGER_CURRENT, true);
 396
 397             /* Charge path regulator turn on takes ~100ms max. */
 398             sleep(HZ/10);
 399
 400             icharger = stat_battery_reading(ADC_CHARGER_CURRENT);
 401
 402             if (icharger != INT_MIN)
 403             {
 404                 icharger_ave = icharger * ICHARGER_AVE_SAMPLES;
 405
 406                 if (update_filtered_battery_voltage())
 407                     return true;
 408             }
 409         }
 410
 411         /* Force regulator OFF. */
 412         charge_state = CHARGE_STATE_ERROR;
 413     }
 414
 415     /* Turn regulator OFF. */
 416     icharger_ave = 0;
 417     i = mc13783_write_masked(MC13783_CHARGER, charger_bits[0][0],
 418                              MC13783_ICHRG | MC13783_VCHRG |
 419                              MC13783_CHRGRAWPDEN);
 420
 421     if (MC13783_DATA_ERROR == i)
 422     {
 423         /* Failed. Force poweroff by not servicing the watchdog. */
 424         service_wdt = false;
 425     }
 426     else if (0 == charger_setting)
 427     {
 428         /* Here because OFF was requested state */
 429         success = true;
 430     }
 431
 432     charger_setting = 0;
 433
 434     adc_enable_channel(ADC_CHARGER_CURRENT, false);
 435     update_filtered_battery_voltage();
 436     charging_set_thread_priority(false);
 437
 438     return success;
 439 }
 440
 441 /* Stop the charger - if USB only then the regulator will not really be
 442  * turned off. ERROR or DISABLED will turn it off however. */
 443 static void stop_charger(void)
 444 {
 445     charger_total_timer = 0;
 446
 447     if (charge_state > DISCHARGING)
 448         charge_state = DISCHARGING;
 449
 450     adjust_charger_current();
 451 }
 452
 453 /* Return OK if it is acceptable to start the regulator. */
 454 static bool charging_ok(void)
 455 {
 456     bool ok = charge_state >= DISCHARGING; /* Not an error condition? */
 457
 458     if (ok)
 459     {
 460         /* Is the battery even connected? */
 461         ok = (last_inputs & POWER_INPUT_BATTERY) != 0;
 462     }
 463
 464     if (ok)
 465     {
 466         /* No tolerance for any over/under temp - wait for it to
 467          * come back into safe range. */
 468         static const signed char temp_ranges[2][2] =
 469         {
 470             { 0, 45 }, /* Temperature range before beginning charging */
 471             { 5, 40 }, /* Temperature range after out-of-range detected */
 472         };
 473
 474         int temp = battery_adc_temp();
 475         const signed char *range = temp_ranges[temp_state];
 476
 477         ok = temp >= range[TEMP_LOW_LIMIT] &&
 478              temp <= range[TEMP_HIGH_LIMIT];
 479
 480         switch (temp_state)
 481         {
 482         case TEMP_STATE_NORMAL:
 483             if (!ok)
 484                 temp_state = TEMP_STATE_WAIT;
 485             break;
 486
 487         case TEMP_STATE_WAIT:
 488             if (ok)
 489                 temp_state = TEMP_STATE_NORMAL;
 490             break;
 491
 492         default:
 493             break;
 494         }
 495     }
 496
 497     if (ok)
 498     {
 499         /* Any events that should stop the regulator? */
 500
 501         /* Overvoltage at CHRGRAW? */
 502         ok = (int_sense0 & MC13783_CHGOVS) == 0;
 503
 504         if (ok)
 505         {
 506             /* CHGCURR sensed? */
 507             ok = (int_sense0 & MC13783_CHGCURRS) != 0;
 508
 509             if (!ok)
 510             {
 511                 /* Debounce transient states */
 512                 if (chgcurr_timer > 0)
 513                 {
 514                     chgcurr_timer--;
 515                     ok = true;
 516                 }
 517             }
 518             else
 519             {
 520                 chgcurr_timer = CHGCURR_TIMEOUT;
 521             }
 522         }
 523
 524         /* Charger may need to be reinserted */
 525         if (!ok)
 526             charge_state = CHARGE_STATE_ERROR;
 527     }
 528
 529     if (charger_setting != 0)
 530     {
 531         if (ok)
 532         {
 533             /* Watch to not overheat FET (nothing should go over about 1012.7mW).
 534              * Trying a higher voltage AC adapter can work (up to 6.90V) but
 535              * we'll just reject that. Reducing current for adapters that bring
 536              * CHRGRAW to > 4.900V is another possible action. */
 537             ok = cccv_regulator_dissipation() < 1150;
 538             if (!ok)
 539                 charge_state = CHARGE_STATE_ERROR;
 540         }
 541
 542         if (!ok)
 543         {
 544             int state = charge_state;
 545
 546             if (state > DISCHARGING)
 547                 state = DISCHARGING;
 548
 549             /* Force off for all states including maintaining the battery level
 550              * on USB. */
 551             charge_state = CHARGE_STATE_ERROR;
 552             stop_charger();
 553             charge_state = state;
 554         }
 555     }
 556
 557     return ok;
 558 }
 559
 560 void powermgmt_init_target(void)
 561 {
 562 #ifdef IMX31_ALLOW_CHARGING
 563     const uint32_t regval_w =
 564         MC13783_VCHRG_4_050V | MC13783_ICHRG_0MA |
 565         MC13783_ICHRGTR_0MA | MC13783_OVCTRL_6_90V;
 566
 567     /* Use watchdog to shut system down if we lose control of the charging
 568      * hardware. */
 569     watchdog_init(WATCHDOG_TIMEOUT);
 570
 571     mc13783_write(MC13783_CHARGER, regval_w);
 572
 573     if (mc13783_read(MC13783_CHARGER) == regval_w)
 574     {
 575         /* Divide CHRGRAW input by 10 */
 576         mc13783_clear(MC13783_ADC0, MC13783_CHRGRAWDIV);
 577         /* Turn off BATTDETB. It's worthless on MESx0V since the battery
 578          * isn't removable (nor the thermistor). */
 579         mc13783_clear(MC13783_POWER_CONTROL0, MC13783_BATTDETEN);
 580     }
 581     else
 582     {
 583         /* Register has the wrong value - set error condition and disable
 584          * since something is wrong. */
 585         charge_state = CHARGE_STATE_DISABLED;
 586         stop_charger();
 587     }
 588 #else
 589     /* Disable charger use */
 590     charge_state = CHARGE_STATE_DISABLED;
 591 #endif
 592 }
 593
 594 /* Returns true if the unit is charging the batteries. */
 595 bool charging_state(void)
 596 {
 597     switch (charge_state)
 598     {
 599     case TRICKLE:
 600     case TOPOFF:
 601     case CHARGING:
 602         return true;
 603     default:
 604         return false;
 605     }
 606 }
 607
 608 /* Filtered battery charge current */
 609 int battery_charge_current(void)
 610 {
 611     return icharger_ave / ICHARGER_AVE_SAMPLES;
 612 }
 613
 614 static void charger_plugged(void)
 615 {
 616     adc_enable_channel(ADC_BATTERY_TEMP, true);
 617     autorecharge_counter = -1;
 618 }
 619
 620 static void charger_unplugged(void)
 621 {
 622     /* Charger pulled - turn off current sources (though hardware
 623      * will have done that anyway). */
 624     if (charge_state > CHARGE_STATE_DISABLED)
 625     {
 626         /* Reset state and clear any error. If disabled, the charger
 627          * will not have been started or will have been stopped already. */
 628         stop_charger();
 629         charge_state = DISCHARGING;
 630     }
 631
 632     /* Might need to reevaluate these bits in charger_none. */
 633     last_inputs &= ~(POWER_INPUT | POWER_INPUT_CHARGER);
 634     temp_state = TEMP_STATE_NORMAL;
 635     autorecharge_counter = 0;
 636     chgcurr_timer = 0;
 637
 638     adc_enable_channel(ADC_BATTERY_TEMP, false);
 639 }
 640
 641 static void charger_none(void)
 642 {
 643     unsigned int pwr = power_thread_inputs;
 644
 645     if (last_inputs != pwr)
 646     {
 647         last_inputs = pwr;
 648
 649         if (charge_state == CHARGE_STATE_DISABLED)
 650             return;
 651
 652         if ((pwr & (POWER_INPUT | POWER_INPUT_CHARGER)) == POWER_INPUT_USB)
 653         {
 654             /* USB connected but not configured. Maintain battery to the
 655              * greatest degree possible. It probably won't be enough but the
 656              * discharge won't be so severe. */
 657             charger_plugged();
 658             charger_setting = CHARGER_ADJUST;
 659         }
 660         else
 661         {
 662             charger_unplugged();
 663             last_inputs = pwr; /* Restore status */
 664         }
 665     }
 666     else if (charger_setting != 0)
 667     {
 668         /* Maintaining - keep filter going and check charge state */
 669         int_sense0 = mc13783_read(MC13783_INTERRUPT_SENSE0);
 670
 671         if (!charger_current_filter_step())
 672         {
 673             /* Failed to read current */
 674             charge_state = CHARGE_STATE_ERROR;
 675         }
 676
 677         charging_ok();
 678     }
 679 }
 680
 681 static void charger_control(void)
 682 {
 683     unsigned int pwr = power_thread_inputs;
 684
 685     if (last_inputs != pwr)
 686     {
 687         unsigned int changed = last_inputs ^ pwr;
 688
 689         last_inputs = pwr;
 690
 691         if (charger_setting != 0)
 692             charger_setting = CHARGER_ADJUST;
 693
 694         if (charge_state == DISCHARGING)
 695         {
 696             if (main_charger_connected())
 697             {
 698                 /* If main is connected, ignore USB plugs. */
 699                 if (changed & POWER_INPUT_MAIN_CHARGER)
 700                 {
 701                     /* Main charger plugged - try charge */
 702                     autorecharge_counter = -1;
 703                 }
 704             }
 705             else if (pwr & POWER_INPUT_USB_CHARGER
 706                         & POWER_INPUT_CHARGER)
 707             {
 708                 /* USB power only */
 709                 if (changed & POWER_INPUT_USB_CHARGER)
 710                 {
 711                     /* USB charger plugged - try charge */
 712                     autorecharge_counter = -1;
 713                 }
 714                 else if (changed & POWER_INPUT_MAIN_CHARGER)
 715                 {
 716                     /* Main charger pulled - go to battery maintenence. */
 717                     charger_setting = CHARGER_ADJUST;
 718                 }
 719             }
 720         }
 721     }
 722
 723     if (charger_setting != 0 && !charger_current_filter_step())
 724     {
 725         /* Failed to read current */
 726         charge_state = CHARGE_STATE_ERROR;
 727     }
 728
 729     int_sense0 = mc13783_read(MC13783_INTERRUPT_SENSE0);
 730
 731     if (!charging_ok())
 732         return;
 733
 734     switch (charge_state)
 735     {
 736     case DISCHARGING:
 737     {
 738         /* Battery voltage may have dropped and a charge cycle should
 739          * start again. Debounced. */
 740         if (autorecharge_counter < 0 &&
 741             battery_adc_voltage() < BATT_FULL_VOLTAGE)
 742         {
 743             /* Try starting a cycle now if battery isn't already topped
 744              * off to allow user to ensure the battery is full. */
 745         }
 746         else if (battery_voltage() > auto_recharge_voltage())
 747         {
 748             /* Still above threshold - reset counter */
 749             autorecharge_counter = AUTORECHARGE_COUNTDOWN;
 750             break;
 751         }
 752         else if (autorecharge_counter > 0)
 753         {
 754             /* Coundown to restart */
 755             autorecharge_counter--;
 756             break;
 757         }
 758
 759         autorecharge_counter = 0;
 760
 761         charging_set_thread_priority(true);
 762
 763         if (stat_battery_reading(ADC_BATTERY) < BATT_VTRICKLE_CHARGE)
 764         {
 765             /* Battery is deeply discharged - precharge at lower current. */
 766             charge_state = TRICKLE;
 767         }
 768         else
 769         {
 770             /* Ok for fast charge */
 771             charge_state = CHARGING;
 772         }
 773
 774         charger_setting = CHARGER_ADJUST;
 775         charger_total_timer = CHARGER_TOTAL_TIMER*60*2;
 776         break;
 777         } /* DISCHARGING: */
 778
 779     case TRICKLE: /* Very low - precharge */
 780     {
 781         if (battery_voltage() <= BATT_VTRICKLE_CHARGE)
 782             break;
 783
 784         /* Switch to normal charge mode. */
 785         charge_state = CHARGING;
 786         charger_setting = CHARGER_ADJUST;
 787         break;
 788         } /* TRICKLE: */
 789
 790     case CHARGING: /* Constant-current stage */
 791     case TOPOFF:   /* Constant-voltage stage */
 792     {
 793         /* Reg. mode is more informative than an operational necessity. */
 794         charge_state = (int_sense0 & MC13783_CCCVS) ? TOPOFF : CHARGING;
 795
 796         if (main_charger_connected())
 797         {
 798             /* Monitor and stop if current drops below threshold. */
 799             if (battery_charge_current() > BATTERY_ICHARGE_COMPLETE)
 800                 break;
 801         }
 802         else
 803         {
 804             /* Accurate I-level can't be determined since device also
 805              * powers through the I sense. This simply stops the reporting
 806              * of charging but the regulator remains on. */
 807             if (battery_voltage() <= BATT_USB_VSTOP)
 808                 break;
 809         }
 810
 811         stop_charger();
 812         break;
 813         } /* CHARGING: TOPOFF: */
 814
 815     default:
 816         break;
 817     } /* switch */
 818
 819     /* Check if charger timer expired and stop it if so. */
 820     if (charger_total_timer > 0 && --charger_total_timer == 0)
 821     {
 822         charge_state = CHARGE_STATE_ERROR;
 823         stop_charger(); /* Time ran out - error */
 824     }
 825 }
 826
 827 /* Main charging algorithm - called from powermgmt.c */
 828 void charging_algorithm_step(void)
 829 {
 830 #ifdef IMX31_ALLOW_CHARGING
 831     if (service_wdt)
 832         watchdog_service();
 833 #endif
 834
 835     /* Switch by input state */
 836     switch (charger_input_state)
 837     {
 838     case NO_CHARGER:
 839         charger_none();
 840         break;
 841
 842     case CHARGER_PLUGGED:
 843         charger_plugged();
 844         break;
 845
 846     case CHARGER:
 847         charger_control();
 848         break;
 849
 850     case CHARGER_UNPLUGGED:
 851         charger_unplugged();
 852         break;
 853     } /* switch */
 854
 855     if (charger_close)
 856     {
 857         if (charge_state != CHARGE_STATE_DISABLED)
 858         {
 859             /* Disable starts while shutting down */
 860             charge_state = CHARGE_STATE_DISABLED;
 861             stop_charger();
 862         }
 863
 864         charger_close = false;
 865         return;
 866     }
 867
 868     if (charger_setting != 0)
 869     {
 870         if ((mc13783_read(MC13783_CHARGER) & (MC13783_ICHRG | MC13783_VCHRG)) !=
 871             charger_setting)
 872         {
 873             /* The hardware setting doesn't match. It could have turned the
 874              * charger off in a race of plugging/unplugging or the setting
 875              * was changed in one of the calls. */
 876             adjust_charger_current();
 877         }
 878     }
 879 }
 880
 881 /* Disable the charger and prepare for poweroff - called off-thread so we
 882  * signal the charging thread to prepare to quit. */
 883 void charging_algorithm_close(void)
 884 {
 885     charger_close = true;
 886
 887     /* Power management thread will set it false again */
 888     while (charger_close)
 889         sleep(HZ/10);
 890 }