drivers/power/ds2760_battery.c

   1 /*
   2  * Driver for batteries with DS2760 chips inside.
   3  *
   4  * Copyright © 2007 Anton Vorontsov
   5  *             2004-2007 Matt Reimer
   6  *             2004 Szabolcs Gyurko
   7  *
   8  * Use consistent with the GNU GPL is permitted,
   9  * provided that this copyright notice is
  10  * preserved in its entirety in all copies and derived works.
  11  *
  12  * Author:  Anton Vorontsov <cbou@mail.ru>
  13  *          February 2007
  14  *
  15  *          Matt Reimer <mreimer@vpop.net>
  16  *          April 2004, 2005, 2007
  17  *
  18  *          Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
  19  *          September 2004
  20  */
  21
  22 #include <linux/module.h>
  23 #include <linux/param.h>
  24 #include <linux/jiffies.h>
  25 #include <linux/workqueue.h>
  26 #include <linux/pm.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/power_supply.h>
  29
  30 #include "../w1/w1.h"
  31 #include "../w1/slaves/w1_ds2760.h"
  32
  33 struct ds2760_device_info {
  34         struct device *dev;
  35
  36         /* DS2760 data, valid after calling ds2760_battery_read_status() */
  37         unsigned long update_time;      /* jiffies when data read */
  38         char raw[DS2760_DATA_SIZE];     /* raw DS2760 data */
  39         int voltage_raw;                /* units of 4.88 mV */
  40         int voltage_uV;                 /* units of µV */
  41         int current_raw;                /* units of 0.625 mA */
  42         int current_uA;                 /* units of µA */
  43         int accum_current_raw;          /* units of 0.25 mAh */
  44         int accum_current_uAh;          /* units of µAh */
  45         int temp_raw;                   /* units of 0.125 °C */
  46         int temp_C;                     /* units of 0.1 °C */
  47         int rated_capacity;             /* units of µAh */
  48         int rem_capacity;               /* percentage */
  49         int full_active_uAh;            /* units of µAh */
  50         int empty_uAh;                  /* units of µAh */
  51         int life_sec;                   /* units of seconds */
  52         int charge_status;              /* POWER_SUPPLY_STATUS_* */
  53
  54         int full_counter;
  55         struct power_supply bat;
  56         struct device *w1_dev;
  57         struct workqueue_struct *monitor_wqueue;
  58         struct delayed_work monitor_work;
  59         struct delayed_work set_charged_work;
  60 };
  61
  62 static unsigned int cache_time = 1000;
  63 module_param(cache_time, uint, 0644);
  64 MODULE_PARM_DESC(cache_time, "cache time in milliseconds");
  65
  66 static unsigned int pmod_enabled;
  67 module_param(pmod_enabled, bool, 0644);
  68 MODULE_PARM_DESC(pmod_enabled, "PMOD enable bit");
  69
  70 static unsigned int rated_capacity;
  71 module_param(rated_capacity, uint, 0644);
  72 MODULE_PARM_DESC(rated_capacity, "rated battery capacity, 10*mAh or index");
  73
  74 static unsigned int current_accum;
  75 module_param(current_accum, uint, 0644);
  76 MODULE_PARM_DESC(current_accum, "current accumulator value");
  77
  78 /* Some batteries have their rated capacity stored a N * 10 mAh, while
  79  * others use an index into this table. */
  80 static int rated_capacities[] = {
  81         0,
  82         920,    /* Samsung */
  83         920,    /* BYD */
  84         920,    /* Lishen */
  85         920,    /* NEC */
  86         1440,   /* Samsung */
  87         1440,   /* BYD */
  88         1440,   /* Lishen */
  89         1440,   /* NEC */
  90         2880,   /* Samsung */
  91         2880,   /* BYD */
  92         2880,   /* Lishen */
  93         2880    /* NEC */
  94 };
  95
  96 /* array is level at temps 0°C, 10°C, 20°C, 30°C, 40°C
  97  * temp is in Celsius */
  98 static int battery_interpolate(int array[], int temp)
  99 {
 100         int index, dt;
 101
 102         if (temp <= 0)
 103                 return array[0];
 104         if (temp >= 40)
 105                 return array[4];
 106
 107         index = temp / 10;
 108         dt    = temp % 10;
 109
 110         return array[index] + (((array[index + 1] - array[index]) * dt) / 10);
 111 }
 112
 113 static int ds2760_battery_read_status(struct ds2760_device_info *di)
 114 {
 115         int ret, i, start, count, scale[5];
 116
 117         if (di->update_time && time_before(jiffies, di->update_time +
 118                                            msecs_to_jiffies(cache_time)))
 119                 return 0;
 120
 121         /* The first time we read the entire contents of SRAM/EEPROM,
 122          * but after that we just read the interesting bits that change. */
 123         if (di->update_time == 0) {
 124                 start = 0;
 125                 count = DS2760_DATA_SIZE;
 126         } else {
 127                 start = DS2760_VOLTAGE_MSB;
 128                 count = DS2760_TEMP_LSB - start + 1;
 129         }
 130
 131         ret = w1_ds2760_read(di->w1_dev, di->raw + start, start, count);
 132         if (ret != count) {
 133                 dev_warn(di->dev, "call to w1_ds2760_read failed (0x%p)\n",
 134                          di->w1_dev);
 135                 return 1;
 136         }
 137
 138         di->update_time = jiffies;
 139
 140         /* DS2760 reports voltage in units of 4.88mV, but the battery class
 141          * reports in units of uV, so convert by multiplying by 4880. */
 142         di->voltage_raw = (di->raw[DS2760_VOLTAGE_MSB] << 3) |
 143                           (di->raw[DS2760_VOLTAGE_LSB] >> 5);
 144         di->voltage_uV = di->voltage_raw * 4880;
 145
 146         /* DS2760 reports current in signed units of 0.625mA, but the battery
 147          * class reports in units of µA, so convert by multiplying by 625. */
 148         di->current_raw =
 149             (((signed char)di->raw[DS2760_CURRENT_MSB]) << 5) |
 150                           (di->raw[DS2760_CURRENT_LSB] >> 3);
 151         di->current_uA = di->current_raw * 625;
 152
 153         /* DS2760 reports accumulated current in signed units of 0.25mAh. */
 154         di->accum_current_raw =
 155             (((signed char)di->raw[DS2760_CURRENT_ACCUM_MSB]) << 8) |
 156                            di->raw[DS2760_CURRENT_ACCUM_LSB];
 157         di->accum_current_uAh = di->accum_current_raw * 250;
 158
 159         /* DS2760 reports temperature in signed units of 0.125°C, but the
 160          * battery class reports in units of 1/10 °C, so we convert by
 161          * multiplying by .125 * 10 = 1.25. */
 162         di->temp_raw = (((signed char)di->raw[DS2760_TEMP_MSB]) << 3) |
 163                                      (di->raw[DS2760_TEMP_LSB] >> 5);
 164         di->temp_C = di->temp_raw + (di->temp_raw / 4);
 165
 166         /* At least some battery monitors (e.g. HP iPAQ) store the battery's
 167          * maximum rated capacity. */
 168         if (di->raw[DS2760_RATED_CAPACITY] < ARRAY_SIZE(rated_capacities))
 169                 di->rated_capacity = rated_capacities[
 170                         (unsigned int)di->raw[DS2760_RATED_CAPACITY]];
 171         else
 172                 di->rated_capacity = di->raw[DS2760_RATED_CAPACITY] * 10;
 173
 174         di->rated_capacity *= 1000; /* convert to µAh */
 175
 176         /* Calculate the full level at the present temperature. */
 177         di->full_active_uAh = di->raw[DS2760_ACTIVE_FULL] << 8 |
 178                               di->raw[DS2760_ACTIVE_FULL + 1];
 179
 180         /* If the full_active_uAh value is not given, fall back to the rated
 181          * capacity. This is likely to happen when chips are not part of the
 182          * battery pack and is therefore not bootstrapped. */
 183         if (di->full_active_uAh == 0)
 184                 di->full_active_uAh = di->rated_capacity / 1000L;
 185
 186         scale[0] = di->full_active_uAh;
 187         for (i = 1; i < 5; i++)
 188                 scale[i] = scale[i - 1] + di->raw[DS2760_ACTIVE_FULL + 2 + i];
 189
 190         di->full_active_uAh = battery_interpolate(scale, di->temp_C / 10);
 191         di->full_active_uAh *= 1000; /* convert to µAh */
 192
 193         /* Calculate the empty level at the present temperature. */
 194         scale[4] = di->raw[DS2760_ACTIVE_EMPTY + 4];
 195         for (i = 3; i >= 0; i--)
 196                 scale[i] = scale[i + 1] + di->raw[DS2760_ACTIVE_EMPTY + i];
 197
 198         di->empty_uAh = battery_interpolate(scale, di->temp_C / 10);
 199         di->empty_uAh *= 1000; /* convert to µAh */
 200
 201         if (di->full_active_uAh == di->empty_uAh)
 202                 di->rem_capacity = 0;
 203         else
 204                 /* From Maxim Application Note 131: remaining capacity =
 205                  * ((ICA - Empty Value) / (Full Value - Empty Value)) x 100% */
 206                 di->rem_capacity = ((di->accum_current_uAh - di->empty_uAh) * 100L) /
 207                                     (di->full_active_uAh - di->empty_uAh);
 208
 209         if (di->rem_capacity < 0)
 210                 di->rem_capacity = 0;
 211         if (di->rem_capacity > 100)
 212                 di->rem_capacity = 100;
 213
 214         if (di->current_uA >= 100L)
 215                 di->life_sec = -((di->accum_current_uAh - di->empty_uAh) * 36L)
 216                                         / (di->current_uA / 100L);
 217         else
 218                 di->life_sec = 0;
 219
 220         return 0;
 221 }
 222
 223 static void ds2760_battery_set_current_accum(struct ds2760_device_info *di,
 224                                              unsigned int acr_val)
 225 {
 226         unsigned char acr[2];
 227
 228         /* acr is in units of 0.25 mAh */
 229         acr_val *= 4L;
 230         acr_val /= 1000;
 231
 232         acr[0] = acr_val >> 8;
 233         acr[1] = acr_val & 0xff;
 234
 235         if (w1_ds2760_write(di->w1_dev, acr, DS2760_CURRENT_ACCUM_MSB, 2) < 2)
 236                 dev_warn(di->dev, "ACR write failed\n");
 237 }
 238
 239 static void ds2760_battery_update_status(struct ds2760_device_info *di)
 240 {
 241         int old_charge_status = di->charge_status;
 242
 243         ds2760_battery_read_status(di);
 244
 245         if (di->charge_status == POWER_SUPPLY_STATUS_UNKNOWN)
 246                 di->full_counter = 0;
 247
 248         if (power_supply_am_i_supplied(&di->bat)) {
 249                 if (di->current_uA > 10000) {
 250                         di->charge_status = POWER_SUPPLY_STATUS_CHARGING;
 251                         di->full_counter = 0;
 252                 } else if (di->current_uA < -5000) {
 253                         if (di->charge_status != POWER_SUPPLY_STATUS_NOT_CHARGING)
 254                                 dev_notice(di->dev, "not enough power to "
 255                                            "charge\n");
 256                         di->charge_status = POWER_SUPPLY_STATUS_NOT_CHARGING;
 257                         di->full_counter = 0;
 258                 } else if (di->current_uA < 10000 &&
 259                             di->charge_status != POWER_SUPPLY_STATUS_FULL) {
 260
 261                         /* Don't consider the battery to be full unless
 262                          * we've seen the current < 10 mA at least two
 263                          * consecutive times. */
 264
 265                         di->full_counter++;
 266
 267                         if (di->full_counter < 2) {
 268                                 di->charge_status = POWER_SUPPLY_STATUS_CHARGING;
 269                         } else {
 270                                 di->charge_status = POWER_SUPPLY_STATUS_FULL;
 271                                 ds2760_battery_set_current_accum(di,
 272                                                 di->full_active_uAh);
 273                         }
 274                 }
 275         } else {
 276                 di->charge_status = POWER_SUPPLY_STATUS_DISCHARGING;
 277                 di->full_counter = 0;
 278         }
 279
 280         if (di->charge_status != old_charge_status)
 281                 power_supply_changed(&di->bat);
 282 }
 283
 284 static void ds2760_battery_write_status(struct ds2760_device_info *di,
 285                                         char status)
 286 {
 287         if (status == di->raw[DS2760_STATUS_REG])
 288                 return;
 289
 290         w1_ds2760_write(di->w1_dev, &status, DS2760_STATUS_WRITE_REG, 1);
 291         w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 292         w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 293 }
 294
 295 static void ds2760_battery_write_rated_capacity(struct ds2760_device_info *di,
 296                                                 unsigned char rated_capacity)
 297 {
 298         if (rated_capacity == di->raw[DS2760_RATED_CAPACITY])
 299                 return;
 300
 301         w1_ds2760_write(di->w1_dev, &rated_capacity, DS2760_RATED_CAPACITY, 1);
 302         w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 303         w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 304 }
 305
 306 static void ds2760_battery_work(struct work_struct *work)
 307 {
 308         struct ds2760_device_info *di = container_of(work,
 309                 struct ds2760_device_info, monitor_work.work);
 310         const int interval = HZ * 60;
 311
 312         dev_dbg(di->dev, "%s\n", __func__);
 313
 314         ds2760_battery_update_status(di);
 315         queue_delayed_work(di->monitor_wqueue, &di->monitor_work, interval);
 316 }
 317
 318 #define to_ds2760_device_info(x) container_of((x), struct ds2760_device_info, \
 319                                               bat);
 320
 321 static void ds2760_battery_external_power_changed(struct power_supply *psy)
 322 {
 323         struct ds2760_device_info *di = to_ds2760_device_info(psy);
 324
 325         dev_dbg(di->dev, "%s\n", __func__);
 326
 327         cancel_delayed_work(&di->monitor_work);
 328         queue_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ/10);
 329 }
 330
 331
 332 static void ds2760_battery_set_charged_work(struct work_struct *work)
 333 {
 334         char bias;
 335         struct ds2760_device_info *di = container_of(work,
 336                 struct ds2760_device_info, set_charged_work.work);
 337
 338         dev_dbg(di->dev, "%s\n", __func__);
 339
 340         ds2760_battery_read_status(di);
 341
 342         /* When we get notified by external circuitry that the battery is
 343          * considered fully charged now, we know that there is no current
 344          * flow any more. However, the ds2760's internal current meter is
 345          * too inaccurate to rely on - spec say something ~15% failure.
 346          * Hence, we use the current offset bias register to compensate
 347          * that error.
 348          */
 349
 350         if (!power_supply_am_i_supplied(&di->bat))
 351                 return;
 352
 353         bias = (signed char) di->current_raw +
 354                 (signed char) di->raw[DS2760_CURRENT_OFFSET_BIAS];
 355
 356         dev_dbg(di->dev, "%s: bias = %d\n", __func__, bias);
 357
 358         w1_ds2760_write(di->w1_dev, &bias, DS2760_CURRENT_OFFSET_BIAS, 1);
 359         w1_ds2760_store_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 360         w1_ds2760_recall_eeprom(di->w1_dev, DS2760_EEPROM_BLOCK1);
 361
 362         /* Write to the di->raw[] buffer directly - the CURRENT_OFFSET_BIAS
 363          * value won't be read back by ds2760_battery_read_status() */
 364         di->raw[DS2760_CURRENT_OFFSET_BIAS] = bias;
 365 }
 366
 367 static void ds2760_battery_set_charged(struct power_supply *psy)
 368 {
 369         struct ds2760_device_info *di = to_ds2760_device_info(psy);
 370
 371         /* postpone the actual work by 20 secs. This is for debouncing GPIO
 372          * signals and to let the current value settle. See AN4188. */
 373         cancel_delayed_work(&di->set_charged_work);
 374         queue_delayed_work(di->monitor_wqueue, &di->set_charged_work, HZ * 20);
 375 }
 376
 377 static int ds2760_battery_get_property(struct power_supply *psy,
 378                                        enum power_supply_property psp,
 379                                        union power_supply_propval *val)
 380 {
 381         struct ds2760_device_info *di = to_ds2760_device_info(psy);
 382
 383         switch (psp) {
 384         case POWER_SUPPLY_PROP_STATUS:
 385                 val->intval = di->charge_status;
 386                 return 0;
 387         default:
 388                 break;
 389         }
 390
 391         ds2760_battery_read_status(di);
 392
 393         switch (psp) {
 394         case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 395                 val->intval = di->voltage_uV;
 396                 break;
 397         case POWER_SUPPLY_PROP_CURRENT_NOW:
 398                 val->intval = di->current_uA;
 399                 break;
 400         case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
 401                 val->intval = di->rated_capacity;
 402                 break;
 403         case POWER_SUPPLY_PROP_CHARGE_FULL:
 404                 val->intval = di->full_active_uAh;
 405                 break;
 406         case POWER_SUPPLY_PROP_CHARGE_EMPTY:
 407                 val->intval = di->empty_uAh;
 408                 break;
 409         case POWER_SUPPLY_PROP_CHARGE_NOW:
 410                 val->intval = di->accum_current_uAh;
 411                 break;
 412         case POWER_SUPPLY_PROP_TEMP:
 413                 val->intval = di->temp_C;
 414                 break;
 415         case POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW:
 416                 val->intval = di->life_sec;
 417                 break;
 418         case POWER_SUPPLY_PROP_CAPACITY:
 419                 val->intval = di->rem_capacity;
 420                 break;
 421         default:
 422                 return -EINVAL;
 423         }
 424
 425         return 0;
 426 }
 427
 428 static enum power_supply_property ds2760_battery_props[] = {
 429         POWER_SUPPLY_PROP_STATUS,
 430         POWER_SUPPLY_PROP_VOLTAGE_NOW,
 431         POWER_SUPPLY_PROP_CURRENT_NOW,
 432         POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
 433         POWER_SUPPLY_PROP_CHARGE_FULL,
 434         POWER_SUPPLY_PROP_CHARGE_EMPTY,
 435         POWER_SUPPLY_PROP_CHARGE_NOW,
 436         POWER_SUPPLY_PROP_TEMP,
 437         POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW,
 438         POWER_SUPPLY_PROP_CAPACITY,
 439 };
 440
 441 static int ds2760_battery_probe(struct platform_device *pdev)
 442 {
 443         char status;
 444         int retval = 0;
 445         struct ds2760_device_info *di;
 446
 447         di = kzalloc(sizeof(*di), GFP_KERNEL);
 448         if (!di) {
 449                 retval = -ENOMEM;
 450                 goto di_alloc_failed;
 451         }
 452
 453         platform_set_drvdata(pdev, di);
 454
 455         di->dev                 = &pdev->dev;
 456         di->w1_dev              = pdev->dev.parent;
 457         di->bat.name            = dev_name(&pdev->dev);
 458         di->bat.type            = POWER_SUPPLY_TYPE_BATTERY;
 459         di->bat.properties      = ds2760_battery_props;
 460         di->bat.num_properties  = ARRAY_SIZE(ds2760_battery_props);
 461         di->bat.get_property    = ds2760_battery_get_property;
 462         di->bat.set_charged     = ds2760_battery_set_charged;
 463         di->bat.external_power_changed =
 464                                   ds2760_battery_external_power_changed;
 465
 466         di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;
 467
 468         /* enable sleep mode feature */
 469         ds2760_battery_read_status(di);
 470         status = di->raw[DS2760_STATUS_REG];
 471         if (pmod_enabled)
 472                 status |= DS2760_STATUS_PMOD;
 473         else
 474                 status &= ~DS2760_STATUS_PMOD;
 475
 476         ds2760_battery_write_status(di, status);
 477
 478         /* set rated capacity from module param */
 479         if (rated_capacity)
 480                 ds2760_battery_write_rated_capacity(di, rated_capacity);
 481
 482         /* set current accumulator if given as parameter.
 483          * this should only be done for bootstrapping the value */
 484         if (current_accum)
 485                 ds2760_battery_set_current_accum(di, current_accum);
 486
 487         retval = power_supply_register(&pdev->dev, &di->bat);
 488         if (retval) {
 489                 dev_err(di->dev, "failed to register battery\n");
 490                 goto batt_failed;
 491         }
 492
 493         INIT_DELAYED_WORK(&di->monitor_work, ds2760_battery_work);
 494         INIT_DELAYED_WORK(&di->set_charged_work,
 495                           ds2760_battery_set_charged_work);
 496         di->monitor_wqueue = create_singlethread_workqueue(dev_name(&pdev->dev));
 497         if (!di->monitor_wqueue) {
 498                 retval = -ESRCH;
 499                 goto workqueue_failed;
 500         }
 501         queue_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ * 1);
 502
 503         goto success;
 504
 505 workqueue_failed:
 506         power_supply_unregister(&di->bat);
 507 batt_failed:
 508         kfree(di);
 509 di_alloc_failed:
 510 success:
 511         return retval;
 512 }
 513
 514 static int ds2760_battery_remove(struct platform_device *pdev)
 515 {
 516         struct ds2760_device_info *di = platform_get_drvdata(pdev);
 517
 518         cancel_rearming_delayed_workqueue(di->monitor_wqueue,
 519                                           &di->monitor_work);
 520         cancel_rearming_delayed_workqueue(di->monitor_wqueue,
 521                                           &di->set_charged_work);
 522         destroy_workqueue(di->monitor_wqueue);
 523         power_supply_unregister(&di->bat);
 524
 525         return 0;
 526 }
 527
 528 #ifdef CONFIG_PM
 529
 530 static int ds2760_battery_suspend(struct platform_device *pdev,
 531                                   pm_message_t state)
 532 {
 533         struct ds2760_device_info *di = platform_get_drvdata(pdev);
 534
 535         di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;
 536
 537         return 0;
 538 }
 539
 540 static int ds2760_battery_resume(struct platform_device *pdev)
 541 {
 542         struct ds2760_device_info *di = platform_get_drvdata(pdev);
 543
 544         di->charge_status = POWER_SUPPLY_STATUS_UNKNOWN;
 545         power_supply_changed(&di->bat);
 546
 547         cancel_delayed_work(&di->monitor_work);
 548         queue_delayed_work(di->monitor_wqueue, &di->monitor_work, HZ);
 549
 550         return 0;
 551 }
 552
 553 #else
 554
 555 #define ds2760_battery_suspend NULL
 556 #define ds2760_battery_resume NULL
 557
 558 #endif /* CONFIG_PM */
 559
 560 MODULE_ALIAS("platform:ds2760-battery");
 561
 562 static struct platform_driver ds2760_battery_driver = {
 563         .driver = {
 564                 .name = "ds2760-battery",
 565         },
 566         .probe    = ds2760_battery_probe,
 567         .remove   = ds2760_battery_remove,
 568         .suspend  = ds2760_battery_suspend,
 569         .resume   = ds2760_battery_resume,
 570 };
 571
 572 static int __init ds2760_battery_init(void)
 573 {
 574         return platform_driver_register(&ds2760_battery_driver);
 575 }
 576
 577 static void __exit ds2760_battery_exit(void)
 578 {
 579         platform_driver_unregister(&ds2760_battery_driver);
 580 }
 581
 582 module_init(ds2760_battery_init);
 583 module_exit(ds2760_battery_exit);
 584
 585 MODULE_LICENSE("GPL");
 586 MODULE_AUTHOR("Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>, "
 587               "Matt Reimer <mreimer@vpop.net>, "
 588               "Anton Vorontsov <cbou@mail.ru>");
 589 MODULE_DESCRIPTION("ds2760 battery driver");