1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Battery monitor driver for the uPI uG3105 battery monitor 4 * 5 * Note the uG3105 is not a full-featured autonomous fuel-gauge. Instead it is 6 * expected to be use in combination with some always on microcontroller reading 7 * its coulomb-counter before it can wrap (must be read every 400 seconds!). 8 * 9 * Since Linux does not monitor coulomb-counter changes while the device 10 * is off or suspended, the coulomb counter is not used atm. 11 * 12 * Possible improvements: 13 * 1. Activate commented out total_coulomb_count code 14 * 2. Reset total_coulomb_count val to 0 when the battery is as good as empty 15 * and remember that we did this (and clear the flag for this on susp/resume) 16 * 3. When the battery is full check if the flag that we set total_coulomb_count 17 * to when the battery was empty is set. If so we now know the capacity, 18 * not the design, but actual capacity, of the battery 19 * 4. Add some mechanism (needs userspace help, or maybe use efivar?) to remember 20 * the actual capacity of the battery over reboots 21 * 5. When we know the actual capacity at probe time, add energy_now and 22 * energy_full attributes. Guess boot + resume energy_now value based on ocv 23 * and then use total_coulomb_count to report energy_now over time, resetting 24 * things to adjust for drift when empty/full. This should give more accurate 25 * readings, esp. in the 30-70% range and allow userspace to estimate time 26 * remaining till empty/full 27 * 6. Maybe unregister + reregister the psy device when we learn the actual 28 * capacity during run-time ? 29 * 30 * The above will also require some sort of mwh_per_unit calculation. Testing 31 * has shown that an estimated 7404mWh increase of the battery's energy results 32 * in a total_coulomb_count increase of 3277 units with a 5 milli-ohm sense R. 33 * 34 * Copyright (C) 2021 Hans de Goede <hdegoede@redhat.com> 35 */ 36 37 #include <linux/devm-helpers.h> 38 #include <linux/module.h> 39 #include <linux/mutex.h> 40 #include <linux/slab.h> 41 #include <linux/i2c.h> 42 #include <linux/mod_devicetable.h> 43 #include <linux/power_supply.h> 44 #include <linux/workqueue.h> 45 46 #define UG3105_MOV_AVG_WINDOW 8 47 #define UG3105_INIT_POLL_TIME (5 * HZ) 48 #define UG3105_POLL_TIME (30 * HZ) 49 #define UG3105_SETTLE_TIME (1 * HZ) 50 51 #define UG3105_INIT_POLL_COUNT 30 52 53 #define UG3105_REG_MODE 0x00 54 #define UG3105_REG_CTRL1 0x01 55 #define UG3105_REG_COULOMB_CNT 0x02 56 #define UG3105_REG_BAT_VOLT 0x08 57 #define UG3105_REG_BAT_CURR 0x0c 58 59 #define UG3105_MODE_STANDBY 0x00 60 #define UG3105_MODE_RUN 0x10 61 62 #define UG3105_CTRL1_RESET_COULOMB_CNT 0x03 63 64 #define UG3105_CURR_HYST_UA 65000 65 66 #define UG3105_LOW_BAT_UV 3700000 67 #define UG3105_FULL_BAT_HYST_UV 38000 68 69 struct ug3105_chip { 70 struct i2c_client *client; 71 struct power_supply *psy; 72 struct power_supply_battery_info *info; 73 struct delayed_work work; 74 struct mutex lock; 75 int ocv[UG3105_MOV_AVG_WINDOW]; /* micro-volt */ 76 int intern_res[UG3105_MOV_AVG_WINDOW]; /* milli-ohm */ 77 int poll_count; 78 int ocv_avg_index; 79 int ocv_avg; /* micro-volt */ 80 int intern_res_poll_count; 81 int intern_res_avg_index; 82 int intern_res_avg; /* milli-ohm */ 83 int volt; /* micro-volt */ 84 int curr; /* micro-ampere */ 85 int total_coulomb_count; 86 int uv_per_unit; 87 int ua_per_unit; 88 int status; 89 int capacity; 90 bool supplied; 91 }; 92 93 static int ug3105_read_word(struct i2c_client *client, u8 reg) 94 { 95 int val; 96 97 val = i2c_smbus_read_word_data(client, reg); 98 if (val < 0) 99 dev_err(&client->dev, "Error reading reg 0x%02x\n", reg); 100 101 return val; 102 } 103 104 static int ug3105_get_status(struct ug3105_chip *chip) 105 { 106 int full = chip->info->constant_charge_voltage_max_uv - UG3105_FULL_BAT_HYST_UV; 107 108 if (chip->curr > UG3105_CURR_HYST_UA) 109 return POWER_SUPPLY_STATUS_CHARGING; 110 111 if (chip->curr < -UG3105_CURR_HYST_UA) 112 return POWER_SUPPLY_STATUS_DISCHARGING; 113 114 if (chip->supplied && chip->ocv_avg > full) 115 return POWER_SUPPLY_STATUS_FULL; 116 117 return POWER_SUPPLY_STATUS_NOT_CHARGING; 118 } 119 120 static int ug3105_get_capacity(struct ug3105_chip *chip) 121 { 122 /* 123 * OCV voltages in uV for 0-110% in 5% increments, the 100-110% is 124 * for LiPo HV (High-Voltage) bateries which can go up to 4.35V 125 * instead of the usual 4.2V. 126 */ 127 static const int ocv_capacity_tbl[23] = { 128 3350000, 129 3610000, 130 3690000, 131 3710000, 132 3730000, 133 3750000, 134 3770000, 135 3786667, 136 3803333, 137 3820000, 138 3836667, 139 3853333, 140 3870000, 141 3907500, 142 3945000, 143 3982500, 144 4020000, 145 4075000, 146 4110000, 147 4150000, 148 4200000, 149 4250000, 150 4300000, 151 }; 152 int i, ocv_diff, ocv_step; 153 154 if (chip->ocv_avg < ocv_capacity_tbl[0]) 155 return 0; 156 157 if (chip->status == POWER_SUPPLY_STATUS_FULL) 158 return 100; 159 160 for (i = 1; i < ARRAY_SIZE(ocv_capacity_tbl); i++) { 161 if (chip->ocv_avg > ocv_capacity_tbl[i]) 162 continue; 163 164 ocv_diff = ocv_capacity_tbl[i] - chip->ocv_avg; 165 ocv_step = ocv_capacity_tbl[i] - ocv_capacity_tbl[i - 1]; 166 /* scale 0-110% down to 0-100% for LiPo HV */ 167 if (chip->info->constant_charge_voltage_max_uv >= 4300000) 168 return (i * 500 - ocv_diff * 500 / ocv_step) / 110; 169 else 170 return i * 5 - ocv_diff * 5 / ocv_step; 171 } 172 173 return 100; 174 } 175 176 static void ug3105_work(struct work_struct *work) 177 { 178 struct ug3105_chip *chip = container_of(work, struct ug3105_chip, 179 work.work); 180 int i, val, curr_diff, volt_diff, res, win_size; 181 bool prev_supplied = chip->supplied; 182 int prev_status = chip->status; 183 int prev_volt = chip->volt; 184 int prev_curr = chip->curr; 185 struct power_supply *psy; 186 187 mutex_lock(&chip->lock); 188 189 psy = chip->psy; 190 if (!psy) 191 goto out; 192 193 val = ug3105_read_word(chip->client, UG3105_REG_BAT_VOLT); 194 if (val < 0) 195 goto out; 196 chip->volt = val * chip->uv_per_unit; 197 198 val = ug3105_read_word(chip->client, UG3105_REG_BAT_CURR); 199 if (val < 0) 200 goto out; 201 chip->curr = (s16)val * chip->ua_per_unit; 202 203 chip->ocv[chip->ocv_avg_index] = 204 chip->volt - chip->curr * chip->intern_res_avg / 1000; 205 chip->ocv_avg_index = (chip->ocv_avg_index + 1) % UG3105_MOV_AVG_WINDOW; 206 chip->poll_count++; 207 208 /* 209 * See possible improvements comment above. 210 * 211 * Read + reset coulomb counter every 10 polls (every 300 seconds) 212 * if ((chip->poll_count % 10) == 0) { 213 * val = ug3105_read_word(chip->client, UG3105_REG_COULOMB_CNT); 214 * if (val < 0) 215 * goto out; 216 * 217 * i2c_smbus_write_byte_data(chip->client, UG3105_REG_CTRL1, 218 * UG3105_CTRL1_RESET_COULOMB_CNT); 219 * 220 * chip->total_coulomb_count += (s16)val; 221 * dev_dbg(&chip->client->dev, "coulomb count %d total %d\n", 222 * (s16)val, chip->total_coulomb_count); 223 * } 224 */ 225 226 chip->ocv_avg = 0; 227 win_size = min(chip->poll_count, UG3105_MOV_AVG_WINDOW); 228 for (i = 0; i < win_size; i++) 229 chip->ocv_avg += chip->ocv[i]; 230 chip->ocv_avg /= win_size; 231 232 chip->supplied = power_supply_am_i_supplied(psy); 233 chip->status = ug3105_get_status(chip); 234 chip->capacity = ug3105_get_capacity(chip); 235 236 /* 237 * Skip internal resistance calc on charger [un]plug and 238 * when the battery is almost empty (voltage low). 239 */ 240 if (chip->supplied != prev_supplied || 241 chip->volt < UG3105_LOW_BAT_UV || 242 chip->poll_count < 2) 243 goto out; 244 245 /* 246 * Assuming that the OCV voltage does not change significantly 247 * between 2 polls, then we can calculate the internal resistance 248 * on a significant current change by attributing all voltage 249 * change between the 2 readings to the internal resistance. 250 */ 251 curr_diff = abs(chip->curr - prev_curr); 252 if (curr_diff < UG3105_CURR_HYST_UA) 253 goto out; 254 255 volt_diff = abs(chip->volt - prev_volt); 256 res = volt_diff * 1000 / curr_diff; 257 258 if ((res < (chip->intern_res_avg * 2 / 3)) || 259 (res > (chip->intern_res_avg * 4 / 3))) { 260 dev_dbg(&chip->client->dev, "Ignoring outlier internal resistance %d mOhm\n", res); 261 goto out; 262 } 263 264 dev_dbg(&chip->client->dev, "Internal resistance %d mOhm\n", res); 265 266 chip->intern_res[chip->intern_res_avg_index] = res; 267 chip->intern_res_avg_index = (chip->intern_res_avg_index + 1) % UG3105_MOV_AVG_WINDOW; 268 chip->intern_res_poll_count++; 269 270 chip->intern_res_avg = 0; 271 win_size = min(chip->intern_res_poll_count, UG3105_MOV_AVG_WINDOW); 272 for (i = 0; i < win_size; i++) 273 chip->intern_res_avg += chip->intern_res[i]; 274 chip->intern_res_avg /= win_size; 275 276 out: 277 mutex_unlock(&chip->lock); 278 279 queue_delayed_work(system_wq, &chip->work, 280 (chip->poll_count <= UG3105_INIT_POLL_COUNT) ? 281 UG3105_INIT_POLL_TIME : UG3105_POLL_TIME); 282 283 if (chip->status != prev_status && psy) 284 power_supply_changed(psy); 285 } 286 287 static enum power_supply_property ug3105_battery_props[] = { 288 POWER_SUPPLY_PROP_STATUS, 289 POWER_SUPPLY_PROP_PRESENT, 290 POWER_SUPPLY_PROP_TECHNOLOGY, 291 POWER_SUPPLY_PROP_SCOPE, 292 POWER_SUPPLY_PROP_VOLTAGE_NOW, 293 POWER_SUPPLY_PROP_VOLTAGE_OCV, 294 POWER_SUPPLY_PROP_CURRENT_NOW, 295 POWER_SUPPLY_PROP_CAPACITY, 296 }; 297 298 static int ug3105_get_property(struct power_supply *psy, 299 enum power_supply_property psp, 300 union power_supply_propval *val) 301 { 302 struct ug3105_chip *chip = power_supply_get_drvdata(psy); 303 int ret = 0; 304 305 mutex_lock(&chip->lock); 306 307 if (!chip->psy) { 308 ret = -EAGAIN; 309 goto out; 310 } 311 312 switch (psp) { 313 case POWER_SUPPLY_PROP_STATUS: 314 val->intval = chip->status; 315 break; 316 case POWER_SUPPLY_PROP_PRESENT: 317 val->intval = 1; 318 break; 319 case POWER_SUPPLY_PROP_TECHNOLOGY: 320 val->intval = chip->info->technology; 321 break; 322 case POWER_SUPPLY_PROP_SCOPE: 323 val->intval = POWER_SUPPLY_SCOPE_SYSTEM; 324 break; 325 case POWER_SUPPLY_PROP_VOLTAGE_NOW: 326 ret = ug3105_read_word(chip->client, UG3105_REG_BAT_VOLT); 327 if (ret < 0) 328 break; 329 val->intval = ret * chip->uv_per_unit; 330 ret = 0; 331 break; 332 case POWER_SUPPLY_PROP_VOLTAGE_OCV: 333 val->intval = chip->ocv_avg; 334 break; 335 case POWER_SUPPLY_PROP_CURRENT_NOW: 336 ret = ug3105_read_word(chip->client, UG3105_REG_BAT_CURR); 337 if (ret < 0) 338 break; 339 val->intval = (s16)ret * chip->ua_per_unit; 340 ret = 0; 341 break; 342 case POWER_SUPPLY_PROP_CAPACITY: 343 val->intval = chip->capacity; 344 break; 345 default: 346 ret = -EINVAL; 347 } 348 349 out: 350 mutex_unlock(&chip->lock); 351 return ret; 352 } 353 354 static void ug3105_external_power_changed(struct power_supply *psy) 355 { 356 struct ug3105_chip *chip = power_supply_get_drvdata(psy); 357 358 dev_dbg(&chip->client->dev, "external power changed\n"); 359 mod_delayed_work(system_wq, &chip->work, UG3105_SETTLE_TIME); 360 } 361 362 static const struct power_supply_desc ug3105_psy_desc = { 363 .name = "ug3105_battery", 364 .type = POWER_SUPPLY_TYPE_BATTERY, 365 .get_property = ug3105_get_property, 366 .external_power_changed = ug3105_external_power_changed, 367 .properties = ug3105_battery_props, 368 .num_properties = ARRAY_SIZE(ug3105_battery_props), 369 }; 370 371 static void ug3105_init(struct ug3105_chip *chip) 372 { 373 chip->poll_count = 0; 374 chip->ocv_avg_index = 0; 375 chip->total_coulomb_count = 0; 376 i2c_smbus_write_byte_data(chip->client, UG3105_REG_MODE, 377 UG3105_MODE_RUN); 378 i2c_smbus_write_byte_data(chip->client, UG3105_REG_CTRL1, 379 UG3105_CTRL1_RESET_COULOMB_CNT); 380 queue_delayed_work(system_wq, &chip->work, 0); 381 flush_delayed_work(&chip->work); 382 } 383 384 static int ug3105_probe(struct i2c_client *client) 385 { 386 struct power_supply_config psy_cfg = {}; 387 struct device *dev = &client->dev; 388 u32 curr_sense_res_uohm = 10000; 389 struct power_supply *psy; 390 struct ug3105_chip *chip; 391 int ret; 392 393 chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL); 394 if (!chip) 395 return -ENOMEM; 396 397 chip->client = client; 398 mutex_init(&chip->lock); 399 ret = devm_delayed_work_autocancel(dev, &chip->work, ug3105_work); 400 if (ret) 401 return ret; 402 403 psy_cfg.drv_data = chip; 404 psy = devm_power_supply_register(dev, &ug3105_psy_desc, &psy_cfg); 405 if (IS_ERR(psy)) 406 return PTR_ERR(psy); 407 408 ret = power_supply_get_battery_info(psy, &chip->info); 409 if (ret) 410 return ret; 411 412 if (chip->info->factory_internal_resistance_uohm == -EINVAL || 413 chip->info->constant_charge_voltage_max_uv == -EINVAL) { 414 dev_err(dev, "error required properties are missing\n"); 415 return -ENODEV; 416 } 417 418 device_property_read_u32(dev, "upisemi,rsns-microohm", &curr_sense_res_uohm); 419 420 /* 421 * DAC maximum is 4.5V divided by 65536 steps + an unknown factor of 10 422 * coming from somewhere for some reason (verified with a volt-meter). 423 */ 424 chip->uv_per_unit = 45000000/65536; 425 /* Datasheet says 8.1 uV per unit for the current ADC */ 426 chip->ua_per_unit = 8100000 / curr_sense_res_uohm; 427 428 /* Use provided internal resistance as start point (in milli-ohm) */ 429 chip->intern_res_avg = chip->info->factory_internal_resistance_uohm / 1000; 430 /* Also add it to the internal resistance moving average window */ 431 chip->intern_res[0] = chip->intern_res_avg; 432 chip->intern_res_avg_index = 1; 433 chip->intern_res_poll_count = 1; 434 435 mutex_lock(&chip->lock); 436 chip->psy = psy; 437 mutex_unlock(&chip->lock); 438 439 ug3105_init(chip); 440 441 i2c_set_clientdata(client, chip); 442 return 0; 443 } 444 445 static int __maybe_unused ug3105_suspend(struct device *dev) 446 { 447 struct ug3105_chip *chip = dev_get_drvdata(dev); 448 449 cancel_delayed_work_sync(&chip->work); 450 i2c_smbus_write_byte_data(chip->client, UG3105_REG_MODE, 451 UG3105_MODE_STANDBY); 452 453 return 0; 454 } 455 456 static int __maybe_unused ug3105_resume(struct device *dev) 457 { 458 struct ug3105_chip *chip = dev_get_drvdata(dev); 459 460 ug3105_init(chip); 461 462 return 0; 463 } 464 465 static SIMPLE_DEV_PM_OPS(ug3105_pm_ops, ug3105_suspend, 466 ug3105_resume); 467 468 static const struct i2c_device_id ug3105_id[] = { 469 { "ug3105" }, 470 { } 471 }; 472 MODULE_DEVICE_TABLE(i2c, ug3105_id); 473 474 static struct i2c_driver ug3105_i2c_driver = { 475 .driver = { 476 .name = "ug3105", 477 .pm = &ug3105_pm_ops, 478 }, 479 .probe = ug3105_probe, 480 .id_table = ug3105_id, 481 }; 482 module_i2c_driver(ug3105_i2c_driver); 483 484 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com"); 485 MODULE_DESCRIPTION("uPI uG3105 battery monitor driver"); 486 MODULE_LICENSE("GPL"); 487