drivers/power/ltc2941-battery-gauge.c

   1 /*
   2  * I2C client/driver for the Linear Technology LTC2941 and LTC2943
   3  * 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/types.h>
  13 #include <linux/errno.h>
  14 #include <linux/swab.h>
  15 #include <linux/i2c.h>
  16 #include <linux/delay.h>
  17 #include <linux/idr.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_THRESH_HIGH_MSB     = 0x04,
  38         LTC294X_REG_THRESH_HIGH_LSB     = 0x05,
  39         LTC294X_REG_THRESH_LOW_MSB      = 0x06,
  40         LTC294X_REG_THRESH_LOW_LSB      = 0x07,
  41         LTC294X_REG_VOLTAGE_MSB = 0x08,
  42         LTC294X_REG_VOLTAGE_LSB = 0x09,
  43         LTC294X_REG_CURRENT_MSB = 0x0E,
  44         LTC294X_REG_CURRENT_LSB = 0x0F,
  45         LTC294X_REG_TEMPERATURE_MSB     = 0x14,
  46         LTC294X_REG_TEMPERATURE_LSB     = 0x15,
  47 };
  48
  49 #define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
  50 #define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
  51 #define LTC294X_REG_CONTROL_PRESCALER_MASK      (BIT(5) | BIT(4) | BIT(3))
  52 #define LTC294X_REG_CONTROL_SHUTDOWN_MASK       (BIT(0))
  53 #define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
  54         ((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
  55 #define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED        0
  56
  57 #define LTC2941_NUM_REGS        0x08
  58 #define LTC2943_NUM_REGS        0x18
  59
  60 struct ltc294x_info {
  61         struct i2c_client *client;      /* I2C Client pointer */
  62         struct power_supply *supply;    /* Supply pointer */
  63         struct power_supply_desc supply_desc;   /* Supply description */
  64         struct delayed_work work;       /* Work scheduler */
  65         int num_regs;   /* Number of registers (chip type) */
  66         int id;         /* Identifier of ltc294x chip */
  67         int charge;     /* Last charge register content */
  68         int r_sense;    /* mOhm */
  69         int Qlsb;       /* nAh */
  70 };
  71
  72 static DEFINE_IDR(ltc294x_id);
  73 static DEFINE_MUTEX(ltc294x_lock);
  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 the 2943 into "monitor" mode, so it measures every 10 sec */
 153         if (info->num_regs == LTC2943_NUM_REGS)
 154                 control |= LTC2943_REG_CONTROL_MODE_SCAN;
 155
 156         if (value != control) {
 157                 ret = ltc294x_write_regs(info->client,
 158                         LTC294X_REG_CONTROL, &control, 1);
 159                 if (ret < 0) {
 160                         dev_err(&info->client->dev,
 161                                 "Could not write register\n");
 162                         goto error_exit;
 163                 }
 164         }
 165
 166         return 0;
 167
 168 error_exit:
 169         return ret;
 170 }
 171
 172 static int ltc294x_read_charge_register(const struct ltc294x_info *info)
 173 {
 174         int ret;
 175         u8 datar[2];
 176
 177         ret = ltc294x_read_regs(info->client,
 178                 LTC294X_REG_ACC_CHARGE_MSB, &datar[0], 2);
 179         if (ret < 0)
 180                 return ret;
 181         return (datar[0] << 8) + datar[1];
 182 }
 183
 184 static int ltc294x_get_charge_now(const struct ltc294x_info *info, int *val)
 185 {
 186         int value = ltc294x_read_charge_register(info);
 187
 188         if (value < 0)
 189                 return value;
 190         /* When r_sense < 0, this counts up when the battery discharges */
 191         if (info->Qlsb < 0)
 192                 value -= 0xFFFF;
 193         *val = convert_bin_to_uAh(info, value);
 194         return 0;
 195 }
 196
 197 static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
 198 {
 199         int ret;
 200         u8 dataw[2];
 201         u8 ctrl_reg;
 202         s32 value;
 203
 204         value = convert_uAh_to_bin(info, val);
 205         /* Direction depends on how sense+/- were connected */
 206         if (info->Qlsb < 0)
 207                 value += 0xFFFF;
 208         if ((value < 0) || (value > 0xFFFF)) /* input validation */
 209                 return -EINVAL;
 210
 211         /* Read control register */
 212         ret = ltc294x_read_regs(info->client,
 213                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 214         if (ret < 0)
 215                 return ret;
 216         /* Disable analog section */
 217         ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
 218         ret = ltc294x_write_regs(info->client,
 219                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 220         if (ret < 0)
 221                 return ret;
 222         /* Set new charge value */
 223         dataw[0] = I16_MSB(value);
 224         dataw[1] = I16_LSB(value);
 225         ret = ltc294x_write_regs(info->client,
 226                 LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
 227         if (ret < 0)
 228                 goto error_exit;
 229         /* Enable analog section */
 230 error_exit:
 231         ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
 232         ret = ltc294x_write_regs(info->client,
 233                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 234
 235         return ret < 0 ? ret : 0;
 236 }
 237
 238 static int ltc294x_get_charge_counter(
 239         const struct ltc294x_info *info, int *val)
 240 {
 241         int value = ltc294x_read_charge_register(info);
 242
 243         if (value < 0)
 244                 return value;
 245         value -= LTC294X_MID_SUPPLY;
 246         *val = convert_bin_to_uAh(info, value);
 247         return 0;
 248 }
 249
 250 static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
 251 {
 252         int ret;
 253         u8 datar[2];
 254         u32 value;
 255
 256         ret = ltc294x_read_regs(info->client,
 257                 LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
 258         value = (datar[0] << 8) | datar[1];
 259         *val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
 260         return ret;
 261 }
 262
 263 static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
 264 {
 265         int ret;
 266         u8 datar[2];
 267         s32 value;
 268
 269         ret = ltc294x_read_regs(info->client,
 270                 LTC294X_REG_CURRENT_MSB, &datar[0], 2);
 271         value = (datar[0] << 8) | datar[1];
 272         value -= 0x7FFF;
 273         /* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
 274          * the formula below keeps everything in s32 range while preserving
 275          * enough digits */
 276         *val = 1000 * ((60000 * value) / (info->r_sense * 0x7FFF)); /* in uA */
 277         return ret;
 278 }
 279
 280 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
 281 {
 282         int ret;
 283         u8 datar[2];
 284         u32 value;
 285
 286         ret = ltc294x_read_regs(info->client,
 287                 LTC294X_REG_TEMPERATURE_MSB, &datar[0], 2);
 288         value = (datar[0] << 8) | datar[1];
 289         /* Full-scale is 510 Kelvin, convert to centidegrees  */
 290         *val = (((51000 * value) / 0xFFFF) - 27215);
 291         return ret;
 292 }
 293
 294 static int ltc294x_get_property(struct power_supply *psy,
 295                                 enum power_supply_property prop,
 296                                 union power_supply_propval *val)
 297 {
 298         struct ltc294x_info *info = power_supply_get_drvdata(psy);
 299
 300         switch (prop) {
 301         case POWER_SUPPLY_PROP_CHARGE_NOW:
 302                 return ltc294x_get_charge_now(info, &val->intval);
 303         case POWER_SUPPLY_PROP_CHARGE_COUNTER:
 304                 return ltc294x_get_charge_counter(info, &val->intval);
 305         case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 306                 return ltc294x_get_voltage(info, &val->intval);
 307         case POWER_SUPPLY_PROP_CURRENT_NOW:
 308                 return ltc294x_get_current(info, &val->intval);
 309         case POWER_SUPPLY_PROP_TEMP:
 310                 return ltc294x_get_temperature(info, &val->intval);
 311         default:
 312                 return -EINVAL;
 313         }
 314 }
 315
 316 static int ltc294x_set_property(struct power_supply *psy,
 317         enum power_supply_property psp,
 318         const union power_supply_propval *val)
 319 {
 320         struct ltc294x_info *info = power_supply_get_drvdata(psy);
 321
 322         switch (psp) {
 323         case POWER_SUPPLY_PROP_CHARGE_NOW:
 324                 return ltc294x_set_charge_now(info, val->intval);
 325         default:
 326                 return -EPERM;
 327         }
 328 }
 329
 330 static int ltc294x_property_is_writeable(
 331         struct power_supply *psy, enum power_supply_property psp)
 332 {
 333         switch (psp) {
 334         case POWER_SUPPLY_PROP_CHARGE_NOW:
 335                 return 1;
 336         default:
 337                 return 0;
 338         }
 339 }
 340
 341 static void ltc294x_update(struct ltc294x_info *info)
 342 {
 343         int charge = ltc294x_read_charge_register(info);
 344
 345         if (charge != info->charge) {
 346                 info->charge = charge;
 347                 power_supply_changed(info->supply);
 348         }
 349 }
 350
 351 static void ltc294x_work(struct work_struct *work)
 352 {
 353         struct ltc294x_info *info;
 354
 355         info = container_of(work, struct ltc294x_info, work.work);
 356         ltc294x_update(info);
 357         schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 358 }
 359
 360 static enum power_supply_property ltc294x_properties[] = {
 361         POWER_SUPPLY_PROP_CHARGE_COUNTER,
 362         POWER_SUPPLY_PROP_CHARGE_NOW,
 363         POWER_SUPPLY_PROP_VOLTAGE_NOW,
 364         POWER_SUPPLY_PROP_CURRENT_NOW,
 365         POWER_SUPPLY_PROP_TEMP,
 366 };
 367
 368 static int ltc294x_i2c_remove(struct i2c_client *client)
 369 {
 370         struct ltc294x_info *info = i2c_get_clientdata(client);
 371
 372         cancel_delayed_work(&info->work);
 373         power_supply_unregister(info->supply);
 374         kfree(info->supply_desc.name);
 375         mutex_lock(&ltc294x_lock);
 376         idr_remove(&ltc294x_id, info->id);
 377         mutex_unlock(&ltc294x_lock);
 378         return 0;
 379 }
 380
 381 static int ltc294x_i2c_probe(struct i2c_client *client,
 382         const struct i2c_device_id *id)
 383 {
 384         struct power_supply_config psy_cfg = {};
 385         struct ltc294x_info *info;
 386         int ret;
 387         int num;
 388         u32 prescaler_exp;
 389         s32 r_sense;
 390         struct device_node *np;
 391
 392         mutex_lock(&ltc294x_lock);
 393         ret = idr_alloc(&ltc294x_id, client, 0, 0, GFP_KERNEL);
 394         mutex_unlock(&ltc294x_lock);
 395         if (ret < 0)
 396                 goto fail_id;
 397
 398         num = ret;
 399
 400         info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
 401         if (info == NULL) {
 402                 ret = -ENOMEM;
 403                 goto fail_info;
 404         }
 405
 406         i2c_set_clientdata(client, info);
 407
 408         info->num_regs = id->driver_data;
 409         info->supply_desc.name = kasprintf(GFP_KERNEL, "%s-%d", client->name,
 410                                            num);
 411         if (!info->supply_desc.name) {
 412                 ret = -ENOMEM;
 413                 goto fail_name;
 414         }
 415
 416         np = of_node_get(client->dev.of_node);
 417
 418         /* r_sense can be negative, when sense+ is connected to the battery
 419          * instead of the sense-. This results in reversed measurements. */
 420         ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
 421         if (ret < 0) {
 422                 dev_err(&client->dev,
 423                         "Could not find lltc,resistor-sense in devicetree\n");
 424                 goto fail_name;
 425         }
 426         info->r_sense = r_sense;
 427
 428         ret = of_property_read_u32(np, "lltc,prescaler-exponent",
 429                 &prescaler_exp);
 430         if (ret < 0) {
 431                 dev_warn(&client->dev,
 432                         "lltc,prescaler-exponent not in devicetree\n");
 433                 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
 434         }
 435
 436         if (info->num_regs == LTC2943_NUM_REGS) {
 437                 if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
 438                         prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
 439                 info->Qlsb = ((340 * 50000) / r_sense) /
 440                                 (4096 / (1 << (2*prescaler_exp)));
 441         } else {
 442                 if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
 443                         prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
 444                 info->Qlsb = ((85 * 50000) / r_sense) /
 445                                 (128 / (1 << prescaler_exp));
 446         }
 447
 448         info->client = client;
 449         info->id = num;
 450         info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
 451         info->supply_desc.properties = ltc294x_properties;
 452         if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
 453                 info->supply_desc.num_properties =
 454                         ARRAY_SIZE(ltc294x_properties);
 455         else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
 456                 info->supply_desc.num_properties =
 457                         ARRAY_SIZE(ltc294x_properties) - 1;
 458         else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
 459                 info->supply_desc.num_properties =
 460                         ARRAY_SIZE(ltc294x_properties) - 2;
 461         else
 462                 info->supply_desc.num_properties =
 463                         ARRAY_SIZE(ltc294x_properties) - 3;
 464         info->supply_desc.get_property = ltc294x_get_property;
 465         info->supply_desc.set_property = ltc294x_set_property;
 466         info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
 467         info->supply_desc.external_power_changed        = NULL;
 468
 469         psy_cfg.drv_data = info;
 470
 471         INIT_DELAYED_WORK(&info->work, ltc294x_work);
 472
 473         ret = ltc294x_reset(info, prescaler_exp);
 474         if (ret < 0) {
 475                 dev_err(&client->dev, "Communication with chip failed\n");
 476                 goto fail_comm;
 477         }
 478
 479         info->supply = power_supply_register(&client->dev, &info->supply_desc,
 480                                              &psy_cfg);
 481         if (IS_ERR(info->supply)) {
 482                 dev_err(&client->dev, "failed to register ltc2941\n");
 483                 ret = PTR_ERR(info->supply);
 484                 goto fail_register;
 485         } else {
 486                 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 487         }
 488
 489         return 0;
 490
 491 fail_register:
 492         kfree(info->supply_desc.name);
 493 fail_comm:
 494 fail_name:
 495 fail_info:
 496         mutex_lock(&ltc294x_lock);
 497         idr_remove(&ltc294x_id, num);
 498         mutex_unlock(&ltc294x_lock);
 499 fail_id:
 500         return ret;
 501 }
 502
 503 #ifdef CONFIG_PM_SLEEP
 504
 505 static int ltc294x_suspend(struct device *dev)
 506 {
 507         struct i2c_client *client = to_i2c_client(dev);
 508         struct ltc294x_info *info = i2c_get_clientdata(client);
 509
 510         cancel_delayed_work(&info->work);
 511         return 0;
 512 }
 513
 514 static int ltc294x_resume(struct device *dev)
 515 {
 516         struct i2c_client *client = to_i2c_client(dev);
 517         struct ltc294x_info *info = i2c_get_clientdata(client);
 518
 519         schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 520         return 0;
 521 }
 522
 523 static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
 524 #define LTC294X_PM_OPS (&ltc294x_pm_ops)
 525
 526 #else
 527 #define LTC294X_PM_OPS NULL
 528 #endif /* CONFIG_PM_SLEEP */
 529
 530
 531 static const struct i2c_device_id ltc294x_i2c_id[] = {
 532         {"ltc2941", LTC2941_NUM_REGS},
 533         {"ltc2943", LTC2943_NUM_REGS},
 534         { },
 535 };
 536 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
 537
 538 static struct i2c_driver ltc294x_driver = {
 539         .driver = {
 540                 .name   = "LTC2941",
 541                 .pm     = LTC294X_PM_OPS,
 542         },
 543         .probe          = ltc294x_i2c_probe,
 544         .remove         = ltc294x_i2c_remove,
 545         .id_table       = ltc294x_i2c_id,
 546 };
 547 module_i2c_driver(ltc294x_driver);
 548
 549 MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
 550 MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
 551 MODULE_DESCRIPTION("LTC2941/LTC2943 Battery Gas Gauge IC driver");
 552 MODULE_LICENSE("GPL");