drivers/power/supply/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/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_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         unsigned long num_regs; /* Number of registers (chip type) */
  66         int charge;     /* Last charge register content */
  67         int r_sense;    /* mOhm */
  68         int Qlsb;       /* nAh */
  69 };
  70
  71 static inline int convert_bin_to_uAh(
  72         const struct ltc294x_info *info, int Q)
  73 {
  74         return ((Q * (info->Qlsb / 10))) / 100;
  75 }
  76
  77 static inline int convert_uAh_to_bin(
  78         const struct ltc294x_info *info, int uAh)
  79 {
  80         int Q;
  81
  82         Q = (uAh * 100) / (info->Qlsb/10);
  83         return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
  84 }
  85
  86 static int ltc294x_read_regs(struct i2c_client *client,
  87         enum ltc294x_reg reg, u8 *buf, int num_regs)
  88 {
  89         int ret;
  90         struct i2c_msg msgs[2] = { };
  91         u8 reg_start = reg;
  92
  93         msgs[0].addr    = client->addr;
  94         msgs[0].len     = 1;
  95         msgs[0].buf     = &reg_start;
  96
  97         msgs[1].addr    = client->addr;
  98         msgs[1].len     = num_regs;
  99         msgs[1].buf     = buf;
 100         msgs[1].flags   = I2C_M_RD;
 101
 102         ret = i2c_transfer(client->adapter, &msgs[0], 2);
 103         if (ret < 0) {
 104                 dev_err(&client->dev, "ltc2941 read_reg failed!\n");
 105                 return ret;
 106         }
 107
 108         dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
 109                 __func__, reg, num_regs, *buf);
 110
 111         return 0;
 112 }
 113
 114 static int ltc294x_write_regs(struct i2c_client *client,
 115         enum ltc294x_reg reg, const u8 *buf, int num_regs)
 116 {
 117         int ret;
 118         u8 reg_start = reg;
 119
 120         ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
 121         if (ret < 0) {
 122                 dev_err(&client->dev, "ltc2941 write_reg failed!\n");
 123                 return ret;
 124         }
 125
 126         dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
 127                 __func__, reg, num_regs, *buf);
 128
 129         return 0;
 130 }
 131
 132 static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
 133 {
 134         int ret;
 135         u8 value;
 136         u8 control;
 137
 138         /* Read status and control registers */
 139         ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
 140         if (ret < 0) {
 141                 dev_err(&info->client->dev,
 142                         "Could not read registers from device\n");
 143                 goto error_exit;
 144         }
 145
 146         control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
 147                                 LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
 148         /* Put the 2943 into "monitor" mode, so it measures every 10 sec */
 149         if (info->num_regs == LTC2943_NUM_REGS)
 150                 control |= LTC2943_REG_CONTROL_MODE_SCAN;
 151
 152         if (value != control) {
 153                 ret = ltc294x_write_regs(info->client,
 154                         LTC294X_REG_CONTROL, &control, 1);
 155                 if (ret < 0) {
 156                         dev_err(&info->client->dev,
 157                                 "Could not write register\n");
 158                         goto error_exit;
 159                 }
 160         }
 161
 162         return 0;
 163
 164 error_exit:
 165         return ret;
 166 }
 167
 168 static int ltc294x_read_charge_register(const struct ltc294x_info *info)
 169 {
 170         int ret;
 171         u8 datar[2];
 172
 173         ret = ltc294x_read_regs(info->client,
 174                 LTC294X_REG_ACC_CHARGE_MSB, &datar[0], 2);
 175         if (ret < 0)
 176                 return ret;
 177         return (datar[0] << 8) + datar[1];
 178 }
 179
 180 static int ltc294x_get_charge_now(const struct ltc294x_info *info, int *val)
 181 {
 182         int value = ltc294x_read_charge_register(info);
 183
 184         if (value < 0)
 185                 return value;
 186         /* When r_sense < 0, this counts up when the battery discharges */
 187         if (info->Qlsb < 0)
 188                 value -= 0xFFFF;
 189         *val = convert_bin_to_uAh(info, value);
 190         return 0;
 191 }
 192
 193 static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
 194 {
 195         int ret;
 196         u8 dataw[2];
 197         u8 ctrl_reg;
 198         s32 value;
 199
 200         value = convert_uAh_to_bin(info, val);
 201         /* Direction depends on how sense+/- were connected */
 202         if (info->Qlsb < 0)
 203                 value += 0xFFFF;
 204         if ((value < 0) || (value > 0xFFFF)) /* input validation */
 205                 return -EINVAL;
 206
 207         /* Read control register */
 208         ret = ltc294x_read_regs(info->client,
 209                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 210         if (ret < 0)
 211                 return ret;
 212         /* Disable analog section */
 213         ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
 214         ret = ltc294x_write_regs(info->client,
 215                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 216         if (ret < 0)
 217                 return ret;
 218         /* Set new charge value */
 219         dataw[0] = I16_MSB(value);
 220         dataw[1] = I16_LSB(value);
 221         ret = ltc294x_write_regs(info->client,
 222                 LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
 223         if (ret < 0)
 224                 goto error_exit;
 225         /* Enable analog section */
 226 error_exit:
 227         ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
 228         ret = ltc294x_write_regs(info->client,
 229                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 230
 231         return ret < 0 ? ret : 0;
 232 }
 233
 234 static int ltc294x_get_charge_counter(
 235         const struct ltc294x_info *info, int *val)
 236 {
 237         int value = ltc294x_read_charge_register(info);
 238
 239         if (value < 0)
 240                 return value;
 241         value -= LTC294X_MID_SUPPLY;
 242         *val = convert_bin_to_uAh(info, value);
 243         return 0;
 244 }
 245
 246 static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
 247 {
 248         int ret;
 249         u8 datar[2];
 250         u32 value;
 251
 252         ret = ltc294x_read_regs(info->client,
 253                 LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
 254         value = (datar[0] << 8) | datar[1];
 255         *val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
 256         return ret;
 257 }
 258
 259 static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
 260 {
 261         int ret;
 262         u8 datar[2];
 263         s32 value;
 264
 265         ret = ltc294x_read_regs(info->client,
 266                 LTC294X_REG_CURRENT_MSB, &datar[0], 2);
 267         value = (datar[0] << 8) | datar[1];
 268         value -= 0x7FFF;
 269         /* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
 270          * the formula below keeps everything in s32 range while preserving
 271          * enough digits */
 272         *val = 1000 * ((60000 * value) / (info->r_sense * 0x7FFF)); /* in uA */
 273         return ret;
 274 }
 275
 276 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
 277 {
 278         int ret;
 279         u8 datar[2];
 280         u32 value;
 281
 282         ret = ltc294x_read_regs(info->client,
 283                 LTC294X_REG_TEMPERATURE_MSB, &datar[0], 2);
 284         value = (datar[0] << 8) | datar[1];
 285         /* Full-scale is 510 Kelvin, convert to centidegrees  */
 286         *val = (((51000 * value) / 0xFFFF) - 27215);
 287         return ret;
 288 }
 289
 290 static int ltc294x_get_property(struct power_supply *psy,
 291                                 enum power_supply_property prop,
 292                                 union power_supply_propval *val)
 293 {
 294         struct ltc294x_info *info = power_supply_get_drvdata(psy);
 295
 296         switch (prop) {
 297         case POWER_SUPPLY_PROP_CHARGE_NOW:
 298                 return ltc294x_get_charge_now(info, &val->intval);
 299         case POWER_SUPPLY_PROP_CHARGE_COUNTER:
 300                 return ltc294x_get_charge_counter(info, &val->intval);
 301         case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 302                 return ltc294x_get_voltage(info, &val->intval);
 303         case POWER_SUPPLY_PROP_CURRENT_NOW:
 304                 return ltc294x_get_current(info, &val->intval);
 305         case POWER_SUPPLY_PROP_TEMP:
 306                 return ltc294x_get_temperature(info, &val->intval);
 307         default:
 308                 return -EINVAL;
 309         }
 310 }
 311
 312 static int ltc294x_set_property(struct power_supply *psy,
 313         enum power_supply_property psp,
 314         const union power_supply_propval *val)
 315 {
 316         struct ltc294x_info *info = power_supply_get_drvdata(psy);
 317
 318         switch (psp) {
 319         case POWER_SUPPLY_PROP_CHARGE_NOW:
 320                 return ltc294x_set_charge_now(info, val->intval);
 321         default:
 322                 return -EPERM;
 323         }
 324 }
 325
 326 static int ltc294x_property_is_writeable(
 327         struct power_supply *psy, enum power_supply_property psp)
 328 {
 329         switch (psp) {
 330         case POWER_SUPPLY_PROP_CHARGE_NOW:
 331                 return 1;
 332         default:
 333                 return 0;
 334         }
 335 }
 336
 337 static void ltc294x_update(struct ltc294x_info *info)
 338 {
 339         int charge = ltc294x_read_charge_register(info);
 340
 341         if (charge != info->charge) {
 342                 info->charge = charge;
 343                 power_supply_changed(info->supply);
 344         }
 345 }
 346
 347 static void ltc294x_work(struct work_struct *work)
 348 {
 349         struct ltc294x_info *info;
 350
 351         info = container_of(work, struct ltc294x_info, work.work);
 352         ltc294x_update(info);
 353         schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 354 }
 355
 356 static enum power_supply_property ltc294x_properties[] = {
 357         POWER_SUPPLY_PROP_CHARGE_COUNTER,
 358         POWER_SUPPLY_PROP_CHARGE_NOW,
 359         POWER_SUPPLY_PROP_VOLTAGE_NOW,
 360         POWER_SUPPLY_PROP_CURRENT_NOW,
 361         POWER_SUPPLY_PROP_TEMP,
 362 };
 363
 364 static int ltc294x_i2c_remove(struct i2c_client *client)
 365 {
 366         struct ltc294x_info *info = i2c_get_clientdata(client);
 367
 368         cancel_delayed_work(&info->work);
 369         power_supply_unregister(info->supply);
 370         return 0;
 371 }
 372
 373 static int ltc294x_i2c_probe(struct i2c_client *client,
 374         const struct i2c_device_id *id)
 375 {
 376         struct power_supply_config psy_cfg = {};
 377         struct ltc294x_info *info;
 378         int ret;
 379         u32 prescaler_exp;
 380         s32 r_sense;
 381         struct device_node *np;
 382
 383         info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
 384         if (info == NULL)
 385                 return -ENOMEM;
 386
 387         i2c_set_clientdata(client, info);
 388
 389         np = of_node_get(client->dev.of_node);
 390
 391         info->num_regs = (unsigned long)of_device_get_match_data(&client->dev);
 392         info->supply_desc.name = np->name;
 393
 394         /* r_sense can be negative, when sense+ is connected to the battery
 395          * instead of the sense-. This results in reversed measurements. */
 396         ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
 397         if (ret < 0) {
 398                 dev_err(&client->dev,
 399                         "Could not find lltc,resistor-sense in devicetree\n");
 400                 return ret;
 401         }
 402         info->r_sense = r_sense;
 403
 404         ret = of_property_read_u32(np, "lltc,prescaler-exponent",
 405                 &prescaler_exp);
 406         if (ret < 0) {
 407                 dev_warn(&client->dev,
 408                         "lltc,prescaler-exponent not in devicetree\n");
 409                 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
 410         }
 411
 412         if (info->num_regs == LTC2943_NUM_REGS) {
 413                 if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
 414                         prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
 415                 info->Qlsb = ((340 * 50000) / r_sense) /
 416                                 (4096 / (1 << (2*prescaler_exp)));
 417         } else {
 418                 if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
 419                         prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
 420                 info->Qlsb = ((85 * 50000) / r_sense) /
 421                                 (128 / (1 << prescaler_exp));
 422         }
 423
 424         info->client = client;
 425         info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
 426         info->supply_desc.properties = ltc294x_properties;
 427         if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
 428                 info->supply_desc.num_properties =
 429                         ARRAY_SIZE(ltc294x_properties);
 430         else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
 431                 info->supply_desc.num_properties =
 432                         ARRAY_SIZE(ltc294x_properties) - 1;
 433         else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
 434                 info->supply_desc.num_properties =
 435                         ARRAY_SIZE(ltc294x_properties) - 2;
 436         else
 437                 info->supply_desc.num_properties =
 438                         ARRAY_SIZE(ltc294x_properties) - 3;
 439         info->supply_desc.get_property = ltc294x_get_property;
 440         info->supply_desc.set_property = ltc294x_set_property;
 441         info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
 442         info->supply_desc.external_power_changed        = NULL;
 443
 444         psy_cfg.drv_data = info;
 445
 446         INIT_DELAYED_WORK(&info->work, ltc294x_work);
 447
 448         ret = ltc294x_reset(info, prescaler_exp);
 449         if (ret < 0) {
 450                 dev_err(&client->dev, "Communication with chip failed\n");
 451                 return ret;
 452         }
 453
 454         info->supply = power_supply_register(&client->dev, &info->supply_desc,
 455                                              &psy_cfg);
 456         if (IS_ERR(info->supply)) {
 457                 dev_err(&client->dev, "failed to register ltc2941\n");
 458                 return PTR_ERR(info->supply);
 459         } else {
 460                 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 461         }
 462
 463         return 0;
 464 }
 465
 466 #ifdef CONFIG_PM_SLEEP
 467
 468 static int ltc294x_suspend(struct device *dev)
 469 {
 470         struct i2c_client *client = to_i2c_client(dev);
 471         struct ltc294x_info *info = i2c_get_clientdata(client);
 472
 473         cancel_delayed_work(&info->work);
 474         return 0;
 475 }
 476
 477 static int ltc294x_resume(struct device *dev)
 478 {
 479         struct i2c_client *client = to_i2c_client(dev);
 480         struct ltc294x_info *info = i2c_get_clientdata(client);
 481
 482         schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 483         return 0;
 484 }
 485
 486 static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
 487 #define LTC294X_PM_OPS (&ltc294x_pm_ops)
 488
 489 #else
 490 #define LTC294X_PM_OPS NULL
 491 #endif /* CONFIG_PM_SLEEP */
 492
 493
 494 static const struct i2c_device_id ltc294x_i2c_id[] = {
 495         {"ltc2941", LTC2941_NUM_REGS},
 496         {"ltc2943", LTC2943_NUM_REGS},
 497         { },
 498 };
 499 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
 500
 501 static const struct of_device_id ltc294x_i2c_of_match[] = {
 502         {
 503                 .compatible = "lltc,ltc2941",
 504                 .data = (void *)LTC2941_NUM_REGS
 505         },
 506         {
 507                 .compatible = "lltc,ltc2943",
 508                 .data = (void *)LTC2943_NUM_REGS
 509         },
 510         { },
 511 };
 512 MODULE_DEVICE_TABLE(of, ltc294x_i2c_of_match);
 513
 514 static struct i2c_driver ltc294x_driver = {
 515         .driver = {
 516                 .name   = "LTC2941",
 517                 .of_match_table = ltc294x_i2c_of_match,
 518                 .pm     = LTC294X_PM_OPS,
 519         },
 520         .probe          = ltc294x_i2c_probe,
 521         .remove         = ltc294x_i2c_remove,
 522         .id_table       = ltc294x_i2c_id,
 523 };
 524 module_i2c_driver(ltc294x_driver);
 525
 526 MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
 527 MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
 528 MODULE_DESCRIPTION("LTC2941/LTC2943 Battery Gas Gauge IC driver");
 529 MODULE_LICENSE("GPL");