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/power_supply.h>
  18 #include <linux/slab.h>
  19
  20 #define I16_MSB(x)                      ((x >> 8) & 0xFF)
  21 #define I16_LSB(x)                      (x & 0xFF)
  22
  23 #define LTC294X_WORK_DELAY              10      /* Update delay in seconds */
  24
  25 #define LTC294X_MAX_VALUE               0xFFFF
  26 #define LTC294X_MID_SUPPLY              0x7FFF
  27
  28 #define LTC2941_MAX_PRESCALER_EXP       7
  29 #define LTC2943_MAX_PRESCALER_EXP       6
  30
  31 enum ltc294x_reg {
  32         LTC294X_REG_STATUS              = 0x00,
  33         LTC294X_REG_CONTROL             = 0x01,
  34         LTC294X_REG_ACC_CHARGE_MSB      = 0x02,
  35         LTC294X_REG_ACC_CHARGE_LSB      = 0x03,
  36         LTC294X_REG_THRESH_HIGH_MSB     = 0x04,
  37         LTC294X_REG_THRESH_HIGH_LSB     = 0x05,
  38         LTC294X_REG_THRESH_LOW_MSB      = 0x06,
  39         LTC294X_REG_THRESH_LOW_LSB      = 0x07,
  40         LTC294X_REG_VOLTAGE_MSB = 0x08,
  41         LTC294X_REG_VOLTAGE_LSB = 0x09,
  42         LTC294X_REG_CURRENT_MSB = 0x0E,
  43         LTC294X_REG_CURRENT_LSB = 0x0F,
  44         LTC294X_REG_TEMPERATURE_MSB     = 0x14,
  45         LTC294X_REG_TEMPERATURE_LSB     = 0x15,
  46 };
  47
  48 #define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
  49 #define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
  50 #define LTC294X_REG_CONTROL_PRESCALER_MASK      (BIT(5) | BIT(4) | BIT(3))
  51 #define LTC294X_REG_CONTROL_SHUTDOWN_MASK       (BIT(0))
  52 #define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
  53         ((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
  54 #define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED        0
  55
  56 #define LTC2941_NUM_REGS        0x08
  57 #define LTC2943_NUM_REGS        0x18
  58
  59 struct ltc294x_info {
  60         struct i2c_client *client;      /* I2C Client pointer */
  61         struct power_supply *supply;    /* Supply pointer */
  62         struct power_supply_desc supply_desc;   /* Supply description */
  63         struct delayed_work work;       /* Work scheduler */
  64         int num_regs;   /* Number of registers (chip type) */
  65         int charge;     /* Last charge register content */
  66         int r_sense;    /* mOhm */
  67         int Qlsb;       /* nAh */
  68 };
  69
  70 static inline int convert_bin_to_uAh(
  71         const struct ltc294x_info *info, int Q)
  72 {
  73         return ((Q * (info->Qlsb / 10))) / 100;
  74 }
  75
  76 static inline int convert_uAh_to_bin(
  77         const struct ltc294x_info *info, int uAh)
  78 {
  79         int Q;
  80
  81         Q = (uAh * 100) / (info->Qlsb/10);
  82         return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
  83 }
  84
  85 static int ltc294x_read_regs(struct i2c_client *client,
  86         enum ltc294x_reg reg, u8 *buf, int num_regs)
  87 {
  88         int ret;
  89         struct i2c_msg msgs[2] = { };
  90         u8 reg_start = reg;
  91
  92         msgs[0].addr    = client->addr;
  93         msgs[0].len     = 1;
  94         msgs[0].buf     = &reg_start;
  95
  96         msgs[1].addr    = client->addr;
  97         msgs[1].len     = num_regs;
  98         msgs[1].buf     = buf;
  99         msgs[1].flags   = I2C_M_RD;
 100
 101         ret = i2c_transfer(client->adapter, &msgs[0], 2);
 102         if (ret < 0) {
 103                 dev_err(&client->dev, "ltc2941 read_reg failed!\n");
 104                 return ret;
 105         }
 106
 107         dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
 108                 __func__, reg, num_regs, *buf);
 109
 110         return 0;
 111 }
 112
 113 static int ltc294x_write_regs(struct i2c_client *client,
 114         enum ltc294x_reg reg, const u8 *buf, int num_regs)
 115 {
 116         int ret;
 117         u8 reg_start = reg;
 118
 119         ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
 120         if (ret < 0) {
 121                 dev_err(&client->dev, "ltc2941 write_reg failed!\n");
 122                 return ret;
 123         }
 124
 125         dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
 126                 __func__, reg, num_regs, *buf);
 127
 128         return 0;
 129 }
 130
 131 static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
 132 {
 133         int ret;
 134         u8 value;
 135         u8 control;
 136
 137         /* Read status and control registers */
 138         ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
 139         if (ret < 0) {
 140                 dev_err(&info->client->dev,
 141                         "Could not read registers from device\n");
 142                 goto error_exit;
 143         }
 144
 145         control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
 146                                 LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
 147         /* Put the 2943 into "monitor" mode, so it measures every 10 sec */
 148         if (info->num_regs == LTC2943_NUM_REGS)
 149                 control |= LTC2943_REG_CONTROL_MODE_SCAN;
 150
 151         if (value != control) {
 152                 ret = ltc294x_write_regs(info->client,
 153                         LTC294X_REG_CONTROL, &control, 1);
 154                 if (ret < 0) {
 155                         dev_err(&info->client->dev,
 156                                 "Could not write register\n");
 157                         goto error_exit;
 158                 }
 159         }
 160
 161         return 0;
 162
 163 error_exit:
 164         return ret;
 165 }
 166
 167 static int ltc294x_read_charge_register(const struct ltc294x_info *info)
 168 {
 169         int ret;
 170         u8 datar[2];
 171
 172         ret = ltc294x_read_regs(info->client,
 173                 LTC294X_REG_ACC_CHARGE_MSB, &datar[0], 2);
 174         if (ret < 0)
 175                 return ret;
 176         return (datar[0] << 8) + datar[1];
 177 }
 178
 179 static int ltc294x_get_charge_now(const struct ltc294x_info *info, int *val)
 180 {
 181         int value = ltc294x_read_charge_register(info);
 182
 183         if (value < 0)
 184                 return value;
 185         /* When r_sense < 0, this counts up when the battery discharges */
 186         if (info->Qlsb < 0)
 187                 value -= 0xFFFF;
 188         *val = convert_bin_to_uAh(info, value);
 189         return 0;
 190 }
 191
 192 static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
 193 {
 194         int ret;
 195         u8 dataw[2];
 196         u8 ctrl_reg;
 197         s32 value;
 198
 199         value = convert_uAh_to_bin(info, val);
 200         /* Direction depends on how sense+/- were connected */
 201         if (info->Qlsb < 0)
 202                 value += 0xFFFF;
 203         if ((value < 0) || (value > 0xFFFF)) /* input validation */
 204                 return -EINVAL;
 205
 206         /* Read control register */
 207         ret = ltc294x_read_regs(info->client,
 208                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 209         if (ret < 0)
 210                 return ret;
 211         /* Disable analog section */
 212         ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
 213         ret = ltc294x_write_regs(info->client,
 214                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 215         if (ret < 0)
 216                 return ret;
 217         /* Set new charge value */
 218         dataw[0] = I16_MSB(value);
 219         dataw[1] = I16_LSB(value);
 220         ret = ltc294x_write_regs(info->client,
 221                 LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
 222         if (ret < 0)
 223                 goto error_exit;
 224         /* Enable analog section */
 225 error_exit:
 226         ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
 227         ret = ltc294x_write_regs(info->client,
 228                 LTC294X_REG_CONTROL, &ctrl_reg, 1);
 229
 230         return ret < 0 ? ret : 0;
 231 }
 232
 233 static int ltc294x_get_charge_counter(
 234         const struct ltc294x_info *info, int *val)
 235 {
 236         int value = ltc294x_read_charge_register(info);
 237
 238         if (value < 0)
 239                 return value;
 240         value -= LTC294X_MID_SUPPLY;
 241         *val = convert_bin_to_uAh(info, value);
 242         return 0;
 243 }
 244
 245 static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
 246 {
 247         int ret;
 248         u8 datar[2];
 249         u32 value;
 250
 251         ret = ltc294x_read_regs(info->client,
 252                 LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
 253         value = (datar[0] << 8) | datar[1];
 254         *val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
 255         return ret;
 256 }
 257
 258 static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
 259 {
 260         int ret;
 261         u8 datar[2];
 262         s32 value;
 263
 264         ret = ltc294x_read_regs(info->client,
 265                 LTC294X_REG_CURRENT_MSB, &datar[0], 2);
 266         value = (datar[0] << 8) | datar[1];
 267         value -= 0x7FFF;
 268         /* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
 269          * the formula below keeps everything in s32 range while preserving
 270          * enough digits */
 271         *val = 1000 * ((60000 * value) / (info->r_sense * 0x7FFF)); /* in uA */
 272         return ret;
 273 }
 274
 275 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
 276 {
 277         int ret;
 278         u8 datar[2];
 279         u32 value;
 280
 281         ret = ltc294x_read_regs(info->client,
 282                 LTC294X_REG_TEMPERATURE_MSB, &datar[0], 2);
 283         value = (datar[0] << 8) | datar[1];
 284         /* Full-scale is 510 Kelvin, convert to centidegrees  */
 285         *val = (((51000 * value) / 0xFFFF) - 27215);
 286         return ret;
 287 }
 288
 289 static int ltc294x_get_property(struct power_supply *psy,
 290                                 enum power_supply_property prop,
 291                                 union power_supply_propval *val)
 292 {
 293         struct ltc294x_info *info = power_supply_get_drvdata(psy);
 294
 295         switch (prop) {
 296         case POWER_SUPPLY_PROP_CHARGE_NOW:
 297                 return ltc294x_get_charge_now(info, &val->intval);
 298         case POWER_SUPPLY_PROP_CHARGE_COUNTER:
 299                 return ltc294x_get_charge_counter(info, &val->intval);
 300         case POWER_SUPPLY_PROP_VOLTAGE_NOW:
 301                 return ltc294x_get_voltage(info, &val->intval);
 302         case POWER_SUPPLY_PROP_CURRENT_NOW:
 303                 return ltc294x_get_current(info, &val->intval);
 304         case POWER_SUPPLY_PROP_TEMP:
 305                 return ltc294x_get_temperature(info, &val->intval);
 306         default:
 307                 return -EINVAL;
 308         }
 309 }
 310
 311 static int ltc294x_set_property(struct power_supply *psy,
 312         enum power_supply_property psp,
 313         const union power_supply_propval *val)
 314 {
 315         struct ltc294x_info *info = power_supply_get_drvdata(psy);
 316
 317         switch (psp) {
 318         case POWER_SUPPLY_PROP_CHARGE_NOW:
 319                 return ltc294x_set_charge_now(info, val->intval);
 320         default:
 321                 return -EPERM;
 322         }
 323 }
 324
 325 static int ltc294x_property_is_writeable(
 326         struct power_supply *psy, enum power_supply_property psp)
 327 {
 328         switch (psp) {
 329         case POWER_SUPPLY_PROP_CHARGE_NOW:
 330                 return 1;
 331         default:
 332                 return 0;
 333         }
 334 }
 335
 336 static void ltc294x_update(struct ltc294x_info *info)
 337 {
 338         int charge = ltc294x_read_charge_register(info);
 339
 340         if (charge != info->charge) {
 341                 info->charge = charge;
 342                 power_supply_changed(info->supply);
 343         }
 344 }
 345
 346 static void ltc294x_work(struct work_struct *work)
 347 {
 348         struct ltc294x_info *info;
 349
 350         info = container_of(work, struct ltc294x_info, work.work);
 351         ltc294x_update(info);
 352         schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 353 }
 354
 355 static enum power_supply_property ltc294x_properties[] = {
 356         POWER_SUPPLY_PROP_CHARGE_COUNTER,
 357         POWER_SUPPLY_PROP_CHARGE_NOW,
 358         POWER_SUPPLY_PROP_VOLTAGE_NOW,
 359         POWER_SUPPLY_PROP_CURRENT_NOW,
 360         POWER_SUPPLY_PROP_TEMP,
 361 };
 362
 363 static int ltc294x_i2c_remove(struct i2c_client *client)
 364 {
 365         struct ltc294x_info *info = i2c_get_clientdata(client);
 366
 367         cancel_delayed_work(&info->work);
 368         power_supply_unregister(info->supply);
 369         return 0;
 370 }
 371
 372 static int ltc294x_i2c_probe(struct i2c_client *client,
 373         const struct i2c_device_id *id)
 374 {
 375         struct power_supply_config psy_cfg = {};
 376         struct ltc294x_info *info;
 377         int ret;
 378         u32 prescaler_exp;
 379         s32 r_sense;
 380         struct device_node *np;
 381
 382         info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
 383         if (info == NULL)
 384                 return -ENOMEM;
 385
 386         i2c_set_clientdata(client, info);
 387
 388         np = of_node_get(client->dev.of_node);
 389
 390         info->num_regs = id->driver_data;
 391         info->supply_desc.name = np->name;
 392
 393         /* r_sense can be negative, when sense+ is connected to the battery
 394          * instead of the sense-. This results in reversed measurements. */
 395         ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
 396         if (ret < 0) {
 397                 dev_err(&client->dev,
 398                         "Could not find lltc,resistor-sense in devicetree\n");
 399                 return ret;
 400         }
 401         info->r_sense = r_sense;
 402
 403         ret = of_property_read_u32(np, "lltc,prescaler-exponent",
 404                 &prescaler_exp);
 405         if (ret < 0) {
 406                 dev_warn(&client->dev,
 407                         "lltc,prescaler-exponent not in devicetree\n");
 408                 prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
 409         }
 410
 411         if (info->num_regs == LTC2943_NUM_REGS) {
 412                 if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
 413                         prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
 414                 info->Qlsb = ((340 * 50000) / r_sense) /
 415                                 (4096 / (1 << (2*prescaler_exp)));
 416         } else {
 417                 if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
 418                         prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
 419                 info->Qlsb = ((85 * 50000) / r_sense) /
 420                                 (128 / (1 << prescaler_exp));
 421         }
 422
 423         info->client = client;
 424         info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
 425         info->supply_desc.properties = ltc294x_properties;
 426         if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
 427                 info->supply_desc.num_properties =
 428                         ARRAY_SIZE(ltc294x_properties);
 429         else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
 430                 info->supply_desc.num_properties =
 431                         ARRAY_SIZE(ltc294x_properties) - 1;
 432         else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
 433                 info->supply_desc.num_properties =
 434                         ARRAY_SIZE(ltc294x_properties) - 2;
 435         else
 436                 info->supply_desc.num_properties =
 437                         ARRAY_SIZE(ltc294x_properties) - 3;
 438         info->supply_desc.get_property = ltc294x_get_property;
 439         info->supply_desc.set_property = ltc294x_set_property;
 440         info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
 441         info->supply_desc.external_power_changed        = NULL;
 442
 443         psy_cfg.drv_data = info;
 444
 445         INIT_DELAYED_WORK(&info->work, ltc294x_work);
 446
 447         ret = ltc294x_reset(info, prescaler_exp);
 448         if (ret < 0) {
 449                 dev_err(&client->dev, "Communication with chip failed\n");
 450                 return ret;
 451         }
 452
 453         info->supply = power_supply_register(&client->dev, &info->supply_desc,
 454                                              &psy_cfg);
 455         if (IS_ERR(info->supply)) {
 456                 dev_err(&client->dev, "failed to register ltc2941\n");
 457                 return PTR_ERR(info->supply);
 458         } else {
 459                 schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 460         }
 461
 462         return 0;
 463 }
 464
 465 #ifdef CONFIG_PM_SLEEP
 466
 467 static int ltc294x_suspend(struct device *dev)
 468 {
 469         struct i2c_client *client = to_i2c_client(dev);
 470         struct ltc294x_info *info = i2c_get_clientdata(client);
 471
 472         cancel_delayed_work(&info->work);
 473         return 0;
 474 }
 475
 476 static int ltc294x_resume(struct device *dev)
 477 {
 478         struct i2c_client *client = to_i2c_client(dev);
 479         struct ltc294x_info *info = i2c_get_clientdata(client);
 480
 481         schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
 482         return 0;
 483 }
 484
 485 static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
 486 #define LTC294X_PM_OPS (&ltc294x_pm_ops)
 487
 488 #else
 489 #define LTC294X_PM_OPS NULL
 490 #endif /* CONFIG_PM_SLEEP */
 491
 492
 493 static const struct i2c_device_id ltc294x_i2c_id[] = {
 494         {"ltc2941", LTC2941_NUM_REGS},
 495         {"ltc2943", LTC2943_NUM_REGS},
 496         { },
 497 };
 498 MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
 499
 500 static struct i2c_driver ltc294x_driver = {
 501         .driver = {
 502                 .name   = "LTC2941",
 503                 .pm     = LTC294X_PM_OPS,
 504         },
 505         .probe          = ltc294x_i2c_probe,
 506         .remove         = ltc294x_i2c_remove,
 507         .id_table       = ltc294x_i2c_id,
 508 };
 509 module_i2c_driver(ltc294x_driver);
 510
 511 MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
 512 MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
 513 MODULE_DESCRIPTION("LTC2941/LTC2943 Battery Gas Gauge IC driver");
 514 MODULE_LICENSE("GPL");