drivers/power/supply/ltc2941-battery-gauge.c

   1 /*
   2  * I2C client/driver for the Linear Technology LTC2941, LTC2942, LTC2943
   3  * and LTC2944 Battery Gas Gauge IC
   4  *
   5  * Copyright (C) 2014 Topic Embedded Systems
   6  *
   7  * Author: Auryn Verwegen
   8  * Author: Mike Looijmans
   9  */
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/of_device.h>
  13 #include <linux/types.h>
  14 #include <linux/errno.h>
  15 #include <linux/swab.h>
  16 #include <linux/i2c.h>
  17 #include <linux/delay.h>
  18 #include <linux/power_supply.h>
  19 #include <linux/slab.h>
  20
  21 #define I16_MSB(x)                      ((x >> 8) & 0xFF)
  22 #define I16_LSB(x)                      (x & 0xFF)
  23
  24 #define LTC294X_WORK_DELAY              10      /* Update delay in seconds */
  25
  26 #define LTC294X_MAX_VALUE               0xFFFF
  27 #define LTC294X_MID_SUPPLY              0x7FFF
  28
  29 #define LTC2941_MAX_PRESCALER_EXP       7
  30 #define LTC2943_MAX_PRESCALER_EXP       6
  31
  32 enum ltc294x_reg {
  33         LTC294X_REG_STATUS              = 0x00,
  34         LTC294X_REG_CONTROL             = 0x01,
  35         LTC294X_REG_ACC_CHARGE_MSB      = 0x02,
  36         LTC294X_REG_ACC_CHARGE_LSB      = 0x03,
  37         LTC294X_REG_VOLTAGE_MSB         = 0x08,
  38         LTC294X_REG_VOLTAGE_LSB         = 0x09,
  39         LTC2942_REG_TEMPERATURE_MSB     = 0x0C,
  40         LTC2942_REG_TEMPERATURE_LSB     = 0x0D,
  41         LTC2943_REG_CURRENT_MSB         = 0x0E,
  42         LTC2943_REG_CURRENT_LSB         = 0x0F,
  43         LTC2943_REG_TEMPERATURE_MSB     = 0x14,
  44         LTC2943_REG_TEMPERATURE_LSB     = 0x15,
  45 };
  46
  47 enum ltc294x_id {
  48         LTC2941_ID,
  49         LTC2942_ID,
  50         LTC2943_ID,
  51         LTC2944_ID,
  52 };
  53
  54 #define LTC2941_REG_STATUS_CHIP_ID      BIT(7)
  55
  56 #define LTC2942_REG_CONTROL_MODE_SCAN   (BIT(7) | BIT(6))
  57 #define LTC2943_REG_CONTROL_MODE_SCAN   BIT(7)
  58 #define LTC294X_REG_CONTROL_PRESCALER_MASK      (BIT(5) | BIT(4) | BIT(3))
  59 #define LTC294X_REG_CONTROL_SHUTDOWN_MASK       (BIT(0))
  60 #define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
  61         ((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
  62 #define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED        0
  63
  64 struct ltc294x_info {
  65         struct i2c_client *client;      /* I2C Client pointer */
  66         struct power_supply *supply;    /* Supply pointer */
  67         struct power_supply_desc supply_desc;   /* Supply description */
  68         struct delayed_work work;       /* Work scheduler */
  69         enum ltc294x_id id;             /* Chip type */
  70         int charge;     /* Last charge register content */
  71         int r_sense;    /* mOhm */
  72         int Qlsb;       /* nAh */
  73 };
  74
  75 static inline int convert_bin_to_uAh(
  76         const struct ltc294x_info *info, int Q)
  77 {
  78         return ((Q * (info->Qlsb / 10))) / 100;
  79 }
  80
  81 static inline int convert_uAh_to_bin(
  82         const struct ltc294x_info *info, int uAh)
  83 {
  84         int Q;
  85
  86         Q = (uAh * 100) / (info->Qlsb/10);
  87         return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
  88 }
  89
  90 static int ltc294x_read_regs(struct i2c_client *client,
  91         enum ltc294x_reg reg, u8 *buf, int num_regs)
  92 {
  93         int ret;
  94         struct i2c_msg msgs[2] = { };
  95         u8 reg_start = reg;
  96
  97         msgs[0].addr    = client->addr;
  98         msgs[0].len     = 1;
  99         msgs[0].buf     = &reg_start;
 100
 101         msgs[1].addr    = client->addr;
 102         msgs[1].len     = num_regs;
 103         msgs[1].buf     = buf;
 104         msgs[1].flags   = I2C_M_RD;
 105
 106         ret = i2c_transfer(client->adapter, &msgs[0], 2);
 107         if (ret < 0) {
 108                 dev_err(&client->dev, "ltc2941 read_reg failed!\n");
 109                 return ret;
 110         }
 111
 112         dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
 113                 __func__, reg, num_regs, *buf);
 114
 115         return 0;
 116 }
 117
 118 static int ltc294x_write_regs(struct i2c_client *client,
 119         enum ltc294x_reg reg, const u8 *buf, int num_regs)
 120 {
 121         int ret;
 122         u8 reg_start = reg;
 123
 124         ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
 125         if (ret < 0) {
 126                 dev_err(&client->dev, "ltc2941 write_reg failed!\n");
 127                 return ret;
 128         }
 129
 130         dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
 131                 __func__, reg, num_regs, *buf);
 132
 133         return 0;
 134 }
 135
 136 static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
 137 {
 138         int ret;
 139         u8 value;
 140         u8 control;
 141
 142         /* Read status and control registers */
 143         ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
 144         if (ret < 0) {
 145                 dev_err(&info->client->dev,
 146                         "Could not read registers from device\n");
 147                 goto error_exit;
 148         }
 149
 150         control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
 151                                 LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
 152         /* Put device into "monitor" mode */
 153         switch (info->id) {
 154         case LTC2942_ID:        /* 2942 measures every 2 sec */
 155                 control |= LTC2942_REG_CONTROL_MODE_SCAN;
 156                 break;
 157         case LTC2943_ID:
 158         case LTC2944_ID:        /* 2943 and 2944 measure every 10 sec */
 159                 control |= LTC2943_REG_CONTROL_MODE_SCAN;
 160                 break;
 161         default:
 162                 break;
 163         }
 164
 165         if (value != control) {
 166                 ret = ltc294x_write_regs(info->client,
 167                         LTC294X_REG_CONTROL, &control, 1);
 168                 if (ret < 0) {
 169                         dev_err(&info->client->dev,
 170                                 "Could not write register\n");
 171                         goto error_exit;
 172                 }
 173         }
 174
 175         return 0;
 176
 177 error_exit:
 178         return ret;
 179 }
 180
 181 static int ltc294x_read_charge_register(const struct ltc294x_info *info)
 182 {
 183         int ret;
 184         u8 datar[2];
 185
 186         ret = ltc294x_read_regs(info->client,
 187                 LTC294X_REG_ACC_CHARGE_MSB, &datar[0], 2);
 188         if (ret < 0)
 189                 return ret;
 190         return (datar[0] << 8) + datar[1];
 191 }
 192
 193 static int ltc294x_get_charge_now(const struct ltc294x_info *info, int *val)
 194 {
 195         int value = ltc294x_read_charge_register(info);
 196
 197         if (value < 0)
 198                 return value;
 199         /* When r_sense < 0, this counts up when the battery discharges */
 200         if (info->Qlsb < 0)
 201                 value -= 0xFFFF;
 202         *val = convert_bin_to_uAh(info, value);
 203         return 0;
 204 }
 205
 206 static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
 207 {
 208         int ret;
 209         u8 dataw[2];
 210         u8 ctrl_reg;
 211         s32 value;
 212
 213         value = convert_uAh_to_bin(info, val);
 214         /* Direction depends on how sense+/- were connected */
 215         if (info->Qlsb < 0)
 216                 value += 0xFFFF;
 217         if ((value < 0) || (value > 0xFFFF)) /* input validation */
 218                 return -EINVAL;
 219
 220         /* Read control register */
 221         ret = ltc294x_read_regs(info->client,
 222                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 223         if (ret < 0)
 224                 return ret;
 225         /* Disable analog section */
 226         ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
 227         ret = ltc294x_write_regs(info->client,
 228                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 229         if (ret < 0)
 230                 return ret;
 231         /* Set new charge value */
 232         dataw[0] = I16_MSB(value);
 233         dataw[1] = I16_LSB(value);
 234         ret = ltc294x_write_regs(info->client,
 235                 LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
 236         if (ret < 0)
 237                 goto error_exit;
 238         /* Enable analog section */
 239 error_exit:
 240         ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
 241         ret = ltc294x_write_regs(info->client,
 242                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 243
 244         return ret < 0 ? ret : 0;
 245 }
 246
 247 static int ltc294x_get_charge_counter(
 248         const struct ltc294x_info *info, int *val)
 249 {
 250         int value = ltc294x_read_charge_register(info);
 251
 252         if (value < 0)
 253                 return value;
 254         value -= LTC294X_MID_SUPPLY;
 255         *val = convert_bin_to_uAh(info, value);
 256         return 0;
 257 }
 258
 259 static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
 260 {
 261         int ret;
 262         u8 datar[2];
 263         u32 value;
 264
 265         ret = ltc294x_read_regs(info->client,
 266                 LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
 267         value = (datar[0] << 8) | datar[1];
 268         switch (info->id) {
 269         case LTC2943_ID:
 270                 value *= 23600 * 2;
 271                 value /= 0xFFFF;
 272                 value *= 1000 / 2;
 273                 break;
 274         case LTC2944_ID:
 275                 value *= 70800 / 5*4;
 276                 value /= 0xFFFF;
 277                 value *= 1000 * 5/4;
 278                 break;
 279         default:
 280                 value *= 6000 * 10;
 281                 value /= 0xFFFF;
 282                 value *= 1000 / 10;
 283                 break;
 284         }
 285         *val = value;
 286         return ret;
 287 }
 288
 289 static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
 290 {
 291         int ret;
 292         u8 datar[2];
 293         s32 value;
 294
 295         ret = ltc294x_read_regs(info->client,
 296                 LTC2943_REG_CURRENT_MSB, &datar[0], 2);
 297         value = (datar[0] << 8) | datar[1];
 298         value -= 0x7FFF;
 299         if (info->id == LTC2944_ID)
 300                 value *= 64000;
 301         else
 302                 value *= 60000;
 303         /* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
 304          * the formula below keeps everything in s32 range while preserving
 305          * enough digits */
 306         *val = 1000 * (value / (info->r_sense * 0x7FFF)); /* in uA */
 307         return ret;
 308 }
 309
 310 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
 311 {
 312         enum ltc294x_reg reg;
 313         int ret;
 314         u8 datar[2];
 315         u32 value;
 316
 317         if (info->id == LTC2942_ID) {
 318                 reg = LTC2942_REG_TEMPERATURE_MSB;
 319                 value = 6000;   /* Full-scale is 600 Kelvin */
 320         } else {
 321                 reg = LTC2943_REG_TEMPERATURE_MSB;
 322                 value = 5100;   /* Full-scale is 510 Kelvin */
 323         }
 324         ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
 325         value *= (datar[0] << 8) | datar[1];
 326         /* Convert to tenths of degree Celsius */
 327         *val = value / 0xFFFF - 2722;
 328         return ret;
 329 }
 330
 331 static int ltc294x_get_property(struct power_supply *psy,
 332                                 enum power_supply_property prop,
 333                                 union power_supply_propval *val)
 334 {
 335         struct ltc294x_info *info = power_supply_get_drvdata(psy);
 336
 337         switch (prop) {
 338         case POWER_SUPPLY_PROP_CHARGE_NOW:
 339                 return ltc294x_get_charge_now(info, &val->intval);
 340         case POWER_SUPPLY_PROP_CHARGE_COUNTER:
 341                 return ltc294x_get_charge_counter(info, &val->intval);
 342         case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 343                 return ltc294x_get_voltage(info, &val->intval);
 344         case POWER_SUPPLY_PROP_CURRENT_NOW:
 345                 return ltc294x_get_current(info, &val->intval);
 346         case POWER_SUPPLY_PROP_TEMP:
 347                 return ltc294x_get_temperature(info, &val->intval);
 348         default:
 349                 return -EINVAL;
 350         }
 351 }
 352
 353 static int ltc294x_set_property(struct power_supply *psy,
 354         enum power_supply_property psp,
 355         const union power_supply_propval *val)
 356 {
 357         struct ltc294x_info *info = power_supply_get_drvdata(psy);
 358
 359         switch (psp) {
 360         case POWER_SUPPLY_PROP_CHARGE_NOW:
 361                 return ltc294x_set_charge_now(info, val->intval);
 362         default:
 363                 return -EPERM;
 364         }
 365 }
 366
 367 static int ltc294x_property_is_writeable(
 368         struct power_supply *psy, enum power_supply_property psp)
 369 {
 370         switch (psp) {
 371         case POWER_SUPPLY_PROP_CHARGE_NOW:
 372                 return 1;
 373         default:
 374                 return 0;
 375         }
 376 }
 377
 378 static void ltc294x_update(struct ltc294x_info *info)
 379 {
 380         int charge = ltc294x_read_charge_register(info);
 381
 382         if (charge != info->charge) {
 383                 info->charge = charge;
 384                 power_supply_changed(info->supply);
 385         }
 386 }
 387
 388 static void ltc294x_work(struct work_struct *work)
 389 {
 390         struct ltc294x_info *info;
 391
 392         info = container_of(work, struct ltc294x_info, work.work);
 393         ltc294x_update(info);
 394         schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 395 }
 396
 397 static enum power_supply_property ltc294x_properties[] = {
 398         POWER_SUPPLY_PROP_CHARGE_COUNTER,
 399         POWER_SUPPLY_PROP_CHARGE_NOW,
 400         POWER_SUPPLY_PROP_VOLTAGE_NOW,
 401         POWER_SUPPLY_PROP_TEMP,
 402         POWER_SUPPLY_PROP_CURRENT_NOW,
 403 };
 404
 405 static int ltc294x_i2c_remove(struct i2c_client *client)
 406 {
 407         struct ltc294x_info *info = i2c_get_clientdata(client);
 408
 409         cancel_delayed_work_sync(&info->work);
 410         power_supply_unregister(info->supply);
 411         return 0;
 412 }
 413
 414 static int ltc294x_i2c_probe(struct i2c_client *client,
 415         const struct i2c_device_id *id)
 416 {
 417         struct power_supply_config psy_cfg = {};
 418         struct ltc294x_info *info;
 419         struct device_node *np;
 420         int ret;
 421         u32 prescaler_exp;
 422         s32 r_sense;
 423         u8 status;
 424
 425         info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
 426         if (info == NULL)
 427                 return -ENOMEM;
 428
 429         i2c_set_clientdata(client, info);
 430
 431         np = of_node_get(client->dev.of_node);
 432
 433         info->id = (enum ltc294x_id)of_device_get_match_data(&client->dev);
 434         info->supply_desc.name = np->name;
 435
 436         /* r_sense can be negative, when sense+ is connected to the battery
 437          * instead of the sense-. This results in reversed measurements. */
 438         ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
 439         if (ret < 0) {
 440                 dev_err(&client->dev,
 441                         "Could not find lltc,resistor-sense in devicetree\n");
 442                 return ret;
 443         }
 444         info->r_sense = r_sense;
 445
 446         ret = of_property_read_u32(np, "lltc,prescaler-exponent",
 447                 &prescaler_exp);
 448         if (ret < 0) {
 449                 dev_warn(&client->dev,
 450                         "lltc,prescaler-exponent not in devicetree\n");
 451                 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
 452         }
 453
 454         if (info->id == LTC2943_ID) {
 455                 if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
 456                         prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
 457                 info->Qlsb = ((340 * 50000) / r_sense) /
 458                                 (4096 / (1 << (2*prescaler_exp)));
 459         } else {
 460                 if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
 461                         prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
 462                 info->Qlsb = ((85 * 50000) / r_sense) /
 463                                 (128 / (1 << prescaler_exp));
 464         }
 465
 466         /* Read status register to check for LTC2942 */
 467         if (info->id == LTC2941_ID || info->id == LTC2942_ID) {
 468                 ret = ltc294x_read_regs(client, LTC294X_REG_STATUS, &status, 1);
 469                 if (ret < 0) {
 470                         dev_err(&client->dev,
 471                                 "Could not read status register\n");
 472                         return ret;
 473                 }
 474                 if (status & LTC2941_REG_STATUS_CHIP_ID)
 475                         info->id = LTC2941_ID;
 476                 else
 477                         info->id = LTC2942_ID;
 478         }
 479
 480         info->client = client;
 481         info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
 482         info->supply_desc.properties = ltc294x_properties;
 483         switch (info->id) {
 484         case LTC2944_ID:
 485         case LTC2943_ID:
 486                 info->supply_desc.num_properties =
 487                         ARRAY_SIZE(ltc294x_properties);
 488                 break;
 489         case LTC2942_ID:
 490                 info->supply_desc.num_properties =
 491                         ARRAY_SIZE(ltc294x_properties) - 1;
 492                 break;
 493         case LTC2941_ID:
 494         default:
 495                 info->supply_desc.num_properties =
 496                         ARRAY_SIZE(ltc294x_properties) - 3;
 497                 break;
 498         }
 499         info->supply_desc.get_property = ltc294x_get_property;
 500         info->supply_desc.set_property = ltc294x_set_property;
 501         info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
 502         info->supply_desc.external_power_changed        = NULL;
 503
 504         psy_cfg.drv_data = info;
 505
 506         INIT_DELAYED_WORK(&info->work, ltc294x_work);
 507
 508         ret = ltc294x_reset(info, prescaler_exp);
 509         if (ret < 0) {
 510                 dev_err(&client->dev, "Communication with chip failed\n");
 511                 return ret;
 512         }
 513
 514         info->supply = power_supply_register(&client->dev, &info->supply_desc,
 515                                              &psy_cfg);
 516         if (IS_ERR(info->supply)) {
 517                 dev_err(&client->dev, "failed to register ltc2941\n");
 518                 return PTR_ERR(info->supply);
 519         } else {
 520                 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 521         }
 522
 523         return 0;
 524 }
 525
 526 #ifdef CONFIG_PM_SLEEP
 527
 528 static int ltc294x_suspend(struct device *dev)
 529 {
 530         struct i2c_client *client = to_i2c_client(dev);
 531         struct ltc294x_info *info = i2c_get_clientdata(client);
 532
 533         cancel_delayed_work(&info->work);
 534         return 0;
 535 }
 536
 537 static int ltc294x_resume(struct device *dev)
 538 {
 539         struct i2c_client *client = to_i2c_client(dev);
 540         struct ltc294x_info *info = i2c_get_clientdata(client);
 541
 542         schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 543         return 0;
 544 }
 545
 546 static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
 547 #define LTC294X_PM_OPS (&ltc294x_pm_ops)
 548
 549 #else
 550 #define LTC294X_PM_OPS NULL
 551 #endif /* CONFIG_PM_SLEEP */
 552
 553
 554 static const struct i2c_device_id ltc294x_i2c_id[] = {
 555         { "ltc2941", LTC2941_ID, },
 556         { "ltc2942", LTC2942_ID, },
 557         { "ltc2943", LTC2943_ID, },
 558         { "ltc2944", LTC2944_ID, },
 559         { },
 560 };
 561 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
 562
 563 static const struct of_device_id ltc294x_i2c_of_match[] = {
 564         {
 565                 .compatible = "lltc,ltc2941",
 566                 .data = (void *)LTC2941_ID,
 567         },
 568         {
 569                 .compatible = "lltc,ltc2942",
 570                 .data = (void *)LTC2942_ID,
 571         },
 572         {
 573                 .compatible = "lltc,ltc2943",
 574                 .data = (void *)LTC2943_ID,
 575         },
 576         {
 577                 .compatible = "lltc,ltc2944",
 578                 .data = (void *)LTC2944_ID,
 579         },
 580         { },
 581 };
 582 MODULE_DEVICE_TABLE(of, ltc294x_i2c_of_match);
 583
 584 static struct i2c_driver ltc294x_driver = {
 585         .driver = {
 586                 .name   = "LTC2941",
 587                 .of_match_table = ltc294x_i2c_of_match,
 588                 .pm     = LTC294X_PM_OPS,
 589         },
 590         .probe          = ltc294x_i2c_probe,
 591         .remove         = ltc294x_i2c_remove,
 592         .id_table       = ltc294x_i2c_id,
 593 };
 594 module_i2c_driver(ltc294x_driver);
 595
 596 MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
 597 MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
 598 MODULE_DESCRIPTION("LTC2941/LTC2942/LTC2943/LTC2944 Battery Gas Gauge IC driver");
 599 MODULE_LICENSE("GPL");