1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Driver for Texas Instruments INA238 power monitor chip 4 * Datasheet: https://www.ti.com/product/ina238 5 * 6 * Copyright (C) 2021 Nathan Rossi <nathan.rossi@digi.com> 7 */ 8 9 #include <linux/err.h> 10 #include <linux/hwmon.h> 11 #include <linux/i2c.h> 12 #include <linux/init.h> 13 #include <linux/kernel.h> 14 #include <linux/module.h> 15 #include <linux/of.h> 16 #include <linux/regmap.h> 17 18 #include <linux/platform_data/ina2xx.h> 19 20 /* INA238 register definitions */ 21 #define INA238_CONFIG 0x0 22 #define INA238_ADC_CONFIG 0x1 23 #define INA238_SHUNT_CALIBRATION 0x2 24 #define INA238_SHUNT_VOLTAGE 0x4 25 #define INA238_BUS_VOLTAGE 0x5 26 #define INA238_DIE_TEMP 0x6 27 #define INA238_CURRENT 0x7 28 #define INA238_POWER 0x8 29 #define INA238_DIAG_ALERT 0xb 30 #define INA238_SHUNT_OVER_VOLTAGE 0xc 31 #define INA238_SHUNT_UNDER_VOLTAGE 0xd 32 #define INA238_BUS_OVER_VOLTAGE 0xe 33 #define INA238_BUS_UNDER_VOLTAGE 0xf 34 #define INA238_TEMP_LIMIT 0x10 35 #define INA238_POWER_LIMIT 0x11 36 #define INA238_DEVICE_ID 0x3f /* not available on INA237 */ 37 38 #define INA238_CONFIG_ADCRANGE BIT(4) 39 40 #define INA238_DIAG_ALERT_TMPOL BIT(7) 41 #define INA238_DIAG_ALERT_SHNTOL BIT(6) 42 #define INA238_DIAG_ALERT_SHNTUL BIT(5) 43 #define INA238_DIAG_ALERT_BUSOL BIT(4) 44 #define INA238_DIAG_ALERT_BUSUL BIT(3) 45 #define INA238_DIAG_ALERT_POL BIT(2) 46 47 #define INA238_REGISTERS 0x11 48 49 #define INA238_RSHUNT_DEFAULT 10000 /* uOhm */ 50 51 /* Default configuration of device on reset. */ 52 #define INA238_CONFIG_DEFAULT 0 53 /* 16 sample averaging, 1052us conversion time, continuous mode */ 54 #define INA238_ADC_CONFIG_DEFAULT 0xfb6a 55 /* Configure alerts to be based on averaged value (SLOWALERT) */ 56 #define INA238_DIAG_ALERT_DEFAULT 0x2000 57 /* 58 * This driver uses a fixed calibration value in order to scale current/power 59 * based on a fixed shunt resistor value. This allows for conversion within the 60 * device to avoid integer limits whilst current/power accuracy is scaled 61 * relative to the shunt resistor value within the driver. This is similar to 62 * how the ina2xx driver handles current/power scaling. 63 * 64 * The end result of this is that increasing shunt values (from a fixed 20 mOhm 65 * shunt) increase the effective current/power accuracy whilst limiting the 66 * range and decreasing shunt values decrease the effective accuracy but 67 * increase the range. 68 * 69 * The value of the Current register is calculated given the following: 70 * Current (A) = (shunt voltage register * 5) * calibration / 81920 71 * 72 * The maximum shunt voltage is 163.835 mV (0x7fff, ADC_RANGE = 0, gain = 4). 73 * With the maximum current value of 0x7fff and a fixed shunt value results in 74 * a calibration value of 16384 (0x4000). 75 * 76 * 0x7fff = (0x7fff * 5) * calibration / 81920 77 * calibration = 0x4000 78 * 79 * Equivalent calibration is applied for the Power register (maximum value for 80 * bus voltage is 102396.875 mV, 0x7fff), where the maximum power that can 81 * occur is ~16776192 uW (register value 0x147a8): 82 * 83 * This scaling means the resulting values for Current and Power registers need 84 * to be scaled by the difference between the fixed shunt resistor and the 85 * actual shunt resistor: 86 * 87 * shunt = 0x4000 / (819.2 * 10^6) / 0.001 = 20000 uOhms (with 1mA/lsb) 88 * 89 * Current (mA) = register value * 20000 / rshunt / 4 * gain 90 * Power (W) = 0.2 * register value * 20000 / rshunt / 4 * gain 91 */ 92 #define INA238_CALIBRATION_VALUE 16384 93 #define INA238_FIXED_SHUNT 20000 94 95 #define INA238_SHUNT_VOLTAGE_LSB 5 /* 5 uV/lsb */ 96 #define INA238_BUS_VOLTAGE_LSB 3125 /* 3.125 mV/lsb */ 97 #define INA238_DIE_TEMP_LSB 125 /* 125 mC/lsb */ 98 99 static struct regmap_config ina238_regmap_config = { 100 .max_register = INA238_REGISTERS, 101 .reg_bits = 8, 102 .val_bits = 16, 103 }; 104 105 struct ina238_data { 106 struct i2c_client *client; 107 struct mutex config_lock; 108 struct regmap *regmap; 109 u32 rshunt; 110 int gain; 111 }; 112 113 static int ina238_read_reg24(const struct i2c_client *client, u8 reg, u32 *val) 114 { 115 u8 data[3]; 116 int err; 117 118 /* 24-bit register read */ 119 err = i2c_smbus_read_i2c_block_data(client, reg, 3, data); 120 if (err < 0) 121 return err; 122 if (err != 3) 123 return -EIO; 124 *val = (data[0] << 16) | (data[1] << 8) | data[2]; 125 126 return 0; 127 } 128 129 static int ina238_read_in(struct device *dev, u32 attr, int channel, 130 long *val) 131 { 132 struct ina238_data *data = dev_get_drvdata(dev); 133 int reg, mask; 134 int regval; 135 int err; 136 137 switch (channel) { 138 case 0: 139 switch (attr) { 140 case hwmon_in_input: 141 reg = INA238_SHUNT_VOLTAGE; 142 break; 143 case hwmon_in_max: 144 reg = INA238_SHUNT_OVER_VOLTAGE; 145 break; 146 case hwmon_in_min: 147 reg = INA238_SHUNT_UNDER_VOLTAGE; 148 break; 149 case hwmon_in_max_alarm: 150 reg = INA238_DIAG_ALERT; 151 mask = INA238_DIAG_ALERT_SHNTOL; 152 break; 153 case hwmon_in_min_alarm: 154 reg = INA238_DIAG_ALERT; 155 mask = INA238_DIAG_ALERT_SHNTUL; 156 break; 157 default: 158 return -EOPNOTSUPP; 159 } 160 break; 161 case 1: 162 switch (attr) { 163 case hwmon_in_input: 164 reg = INA238_BUS_VOLTAGE; 165 break; 166 case hwmon_in_max: 167 reg = INA238_BUS_OVER_VOLTAGE; 168 break; 169 case hwmon_in_min: 170 reg = INA238_BUS_UNDER_VOLTAGE; 171 break; 172 case hwmon_in_max_alarm: 173 reg = INA238_DIAG_ALERT; 174 mask = INA238_DIAG_ALERT_BUSOL; 175 break; 176 case hwmon_in_min_alarm: 177 reg = INA238_DIAG_ALERT; 178 mask = INA238_DIAG_ALERT_BUSUL; 179 break; 180 default: 181 return -EOPNOTSUPP; 182 } 183 break; 184 default: 185 return -EOPNOTSUPP; 186 } 187 188 err = regmap_read(data->regmap, reg, ®val); 189 if (err < 0) 190 return err; 191 192 switch (attr) { 193 case hwmon_in_input: 194 case hwmon_in_max: 195 case hwmon_in_min: 196 /* signed register, value in mV */ 197 regval = (s16)regval; 198 if (channel == 0) 199 /* gain of 1 -> LSB / 4 */ 200 *val = (regval * INA238_SHUNT_VOLTAGE_LSB) / 201 (1000 * (4 - data->gain + 1)); 202 else 203 *val = (regval * INA238_BUS_VOLTAGE_LSB) / 1000; 204 break; 205 case hwmon_in_max_alarm: 206 case hwmon_in_min_alarm: 207 *val = !!(regval & mask); 208 break; 209 } 210 211 return 0; 212 } 213 214 static int ina238_write_in(struct device *dev, u32 attr, int channel, 215 long val) 216 { 217 struct ina238_data *data = dev_get_drvdata(dev); 218 int regval; 219 220 if (attr != hwmon_in_max && attr != hwmon_in_min) 221 return -EOPNOTSUPP; 222 223 /* convert decimal to register value */ 224 switch (channel) { 225 case 0: 226 /* signed value, clamp to max range +/-163 mV */ 227 regval = clamp_val(val, -163, 163); 228 regval = (regval * 1000 * (4 - data->gain + 1)) / 229 INA238_SHUNT_VOLTAGE_LSB; 230 regval = clamp_val(regval, S16_MIN, S16_MAX); 231 232 switch (attr) { 233 case hwmon_in_max: 234 return regmap_write(data->regmap, 235 INA238_SHUNT_OVER_VOLTAGE, regval); 236 case hwmon_in_min: 237 return regmap_write(data->regmap, 238 INA238_SHUNT_UNDER_VOLTAGE, regval); 239 default: 240 return -EOPNOTSUPP; 241 } 242 case 1: 243 /* signed value, positive values only. Clamp to max 102.396 V */ 244 regval = clamp_val(val, 0, 102396); 245 regval = (regval * 1000) / INA238_BUS_VOLTAGE_LSB; 246 regval = clamp_val(regval, 0, S16_MAX); 247 248 switch (attr) { 249 case hwmon_in_max: 250 return regmap_write(data->regmap, 251 INA238_BUS_OVER_VOLTAGE, regval); 252 case hwmon_in_min: 253 return regmap_write(data->regmap, 254 INA238_BUS_UNDER_VOLTAGE, regval); 255 default: 256 return -EOPNOTSUPP; 257 } 258 default: 259 return -EOPNOTSUPP; 260 } 261 } 262 263 static int ina238_read_current(struct device *dev, u32 attr, long *val) 264 { 265 struct ina238_data *data = dev_get_drvdata(dev); 266 int regval; 267 int err; 268 269 switch (attr) { 270 case hwmon_curr_input: 271 err = regmap_read(data->regmap, INA238_CURRENT, ®val); 272 if (err < 0) 273 return err; 274 275 /* Signed register, fixed 1mA current lsb. result in mA */ 276 *val = div_s64((s16)regval * INA238_FIXED_SHUNT * data->gain, 277 data->rshunt * 4); 278 break; 279 default: 280 return -EOPNOTSUPP; 281 } 282 283 return 0; 284 } 285 286 static int ina238_read_power(struct device *dev, u32 attr, long *val) 287 { 288 struct ina238_data *data = dev_get_drvdata(dev); 289 long long power; 290 int regval; 291 int err; 292 293 switch (attr) { 294 case hwmon_power_input: 295 err = ina238_read_reg24(data->client, INA238_POWER, ®val); 296 if (err) 297 return err; 298 299 /* Fixed 1mA lsb, scaled by 1000000 to have result in uW */ 300 power = div_u64(regval * 1000ULL * INA238_FIXED_SHUNT * 301 data->gain, 20 * data->rshunt); 302 /* Clamp value to maximum value of long */ 303 *val = clamp_val(power, 0, LONG_MAX); 304 break; 305 case hwmon_power_max: 306 err = regmap_read(data->regmap, INA238_POWER_LIMIT, ®val); 307 if (err) 308 return err; 309 310 /* 311 * Truncated 24-bit compare register, lower 8-bits are 312 * truncated. Same conversion to/from uW as POWER register. 313 */ 314 power = div_u64((regval << 8) * 1000ULL * INA238_FIXED_SHUNT * 315 data->gain, 20 * data->rshunt); 316 /* Clamp value to maximum value of long */ 317 *val = clamp_val(power, 0, LONG_MAX); 318 break; 319 case hwmon_power_max_alarm: 320 err = regmap_read(data->regmap, INA238_DIAG_ALERT, ®val); 321 if (err) 322 return err; 323 324 *val = !!(regval & INA238_DIAG_ALERT_POL); 325 break; 326 default: 327 return -EOPNOTSUPP; 328 } 329 330 return 0; 331 } 332 333 static int ina238_write_power(struct device *dev, u32 attr, long val) 334 { 335 struct ina238_data *data = dev_get_drvdata(dev); 336 long regval; 337 338 if (attr != hwmon_power_max) 339 return -EOPNOTSUPP; 340 341 /* 342 * Unsigned postive values. Compared against the 24-bit power register, 343 * lower 8-bits are truncated. Same conversion to/from uW as POWER 344 * register. 345 */ 346 regval = clamp_val(val, 0, LONG_MAX); 347 regval = div_u64(val * 20ULL * data->rshunt, 348 1000ULL * INA238_FIXED_SHUNT * data->gain); 349 regval = clamp_val(regval >> 8, 0, U16_MAX); 350 351 return regmap_write(data->regmap, INA238_POWER_LIMIT, regval); 352 } 353 354 static int ina238_read_temp(struct device *dev, u32 attr, long *val) 355 { 356 struct ina238_data *data = dev_get_drvdata(dev); 357 int regval; 358 int err; 359 360 switch (attr) { 361 case hwmon_temp_input: 362 err = regmap_read(data->regmap, INA238_DIE_TEMP, ®val); 363 if (err) 364 return err; 365 366 /* Signed, bits 15-4 of register, result in mC */ 367 *val = ((s16)regval >> 4) * INA238_DIE_TEMP_LSB; 368 break; 369 case hwmon_temp_max: 370 err = regmap_read(data->regmap, INA238_TEMP_LIMIT, ®val); 371 if (err) 372 return err; 373 374 /* Signed, bits 15-4 of register, result in mC */ 375 *val = ((s16)regval >> 4) * INA238_DIE_TEMP_LSB; 376 break; 377 case hwmon_temp_max_alarm: 378 err = regmap_read(data->regmap, INA238_DIAG_ALERT, ®val); 379 if (err) 380 return err; 381 382 *val = !!(regval & INA238_DIAG_ALERT_TMPOL); 383 break; 384 default: 385 return -EOPNOTSUPP; 386 } 387 388 return 0; 389 } 390 391 static int ina238_write_temp(struct device *dev, u32 attr, long val) 392 { 393 struct ina238_data *data = dev_get_drvdata(dev); 394 int regval; 395 396 if (attr != hwmon_temp_max) 397 return -EOPNOTSUPP; 398 399 /* Signed, bits 15-4 of register */ 400 regval = (val / INA238_DIE_TEMP_LSB) << 4; 401 regval = clamp_val(regval, S16_MIN, S16_MAX) & 0xfff0; 402 403 return regmap_write(data->regmap, INA238_TEMP_LIMIT, regval); 404 } 405 406 static int ina238_read(struct device *dev, enum hwmon_sensor_types type, 407 u32 attr, int channel, long *val) 408 { 409 switch (type) { 410 case hwmon_in: 411 return ina238_read_in(dev, attr, channel, val); 412 case hwmon_curr: 413 return ina238_read_current(dev, attr, val); 414 case hwmon_power: 415 return ina238_read_power(dev, attr, val); 416 case hwmon_temp: 417 return ina238_read_temp(dev, attr, val); 418 default: 419 return -EOPNOTSUPP; 420 } 421 return 0; 422 } 423 424 static int ina238_write(struct device *dev, enum hwmon_sensor_types type, 425 u32 attr, int channel, long val) 426 { 427 struct ina238_data *data = dev_get_drvdata(dev); 428 int err; 429 430 mutex_lock(&data->config_lock); 431 432 switch (type) { 433 case hwmon_in: 434 err = ina238_write_in(dev, attr, channel, val); 435 break; 436 case hwmon_power: 437 err = ina238_write_power(dev, attr, val); 438 break; 439 case hwmon_temp: 440 err = ina238_write_temp(dev, attr, val); 441 break; 442 default: 443 err = -EOPNOTSUPP; 444 break; 445 } 446 447 mutex_unlock(&data->config_lock); 448 return err; 449 } 450 451 static umode_t ina238_is_visible(const void *drvdata, 452 enum hwmon_sensor_types type, 453 u32 attr, int channel) 454 { 455 switch (type) { 456 case hwmon_in: 457 switch (attr) { 458 case hwmon_in_input: 459 case hwmon_in_max_alarm: 460 case hwmon_in_min_alarm: 461 return 0444; 462 case hwmon_in_max: 463 case hwmon_in_min: 464 return 0644; 465 default: 466 return 0; 467 } 468 case hwmon_curr: 469 switch (attr) { 470 case hwmon_curr_input: 471 return 0444; 472 default: 473 return 0; 474 } 475 case hwmon_power: 476 switch (attr) { 477 case hwmon_power_input: 478 case hwmon_power_max_alarm: 479 return 0444; 480 case hwmon_power_max: 481 return 0644; 482 default: 483 return 0; 484 } 485 case hwmon_temp: 486 switch (attr) { 487 case hwmon_temp_input: 488 case hwmon_temp_max_alarm: 489 return 0444; 490 case hwmon_temp_max: 491 return 0644; 492 default: 493 return 0; 494 } 495 default: 496 return 0; 497 } 498 } 499 500 #define INA238_HWMON_IN_CONFIG (HWMON_I_INPUT | \ 501 HWMON_I_MAX | HWMON_I_MAX_ALARM | \ 502 HWMON_I_MIN | HWMON_I_MIN_ALARM) 503 504 static const struct hwmon_channel_info * const ina238_info[] = { 505 HWMON_CHANNEL_INFO(in, 506 /* 0: shunt voltage */ 507 INA238_HWMON_IN_CONFIG, 508 /* 1: bus voltage */ 509 INA238_HWMON_IN_CONFIG), 510 HWMON_CHANNEL_INFO(curr, 511 /* 0: current through shunt */ 512 HWMON_C_INPUT), 513 HWMON_CHANNEL_INFO(power, 514 /* 0: power */ 515 HWMON_P_INPUT | HWMON_P_MAX | HWMON_P_MAX_ALARM), 516 HWMON_CHANNEL_INFO(temp, 517 /* 0: die temperature */ 518 HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_ALARM), 519 NULL 520 }; 521 522 static const struct hwmon_ops ina238_hwmon_ops = { 523 .is_visible = ina238_is_visible, 524 .read = ina238_read, 525 .write = ina238_write, 526 }; 527 528 static const struct hwmon_chip_info ina238_chip_info = { 529 .ops = &ina238_hwmon_ops, 530 .info = ina238_info, 531 }; 532 533 static int ina238_probe(struct i2c_client *client) 534 { 535 struct ina2xx_platform_data *pdata = dev_get_platdata(&client->dev); 536 struct device *dev = &client->dev; 537 struct device *hwmon_dev; 538 struct ina238_data *data; 539 int config; 540 int ret; 541 542 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 543 if (!data) 544 return -ENOMEM; 545 546 data->client = client; 547 mutex_init(&data->config_lock); 548 549 data->regmap = devm_regmap_init_i2c(client, &ina238_regmap_config); 550 if (IS_ERR(data->regmap)) { 551 dev_err(dev, "failed to allocate register map\n"); 552 return PTR_ERR(data->regmap); 553 } 554 555 /* load shunt value */ 556 data->rshunt = INA238_RSHUNT_DEFAULT; 557 if (device_property_read_u32(dev, "shunt-resistor", &data->rshunt) < 0 && pdata) 558 data->rshunt = pdata->shunt_uohms; 559 if (data->rshunt == 0) { 560 dev_err(dev, "invalid shunt resister value %u\n", data->rshunt); 561 return -EINVAL; 562 } 563 564 /* load shunt gain value */ 565 if (device_property_read_u32(dev, "ti,shunt-gain", &data->gain) < 0) 566 data->gain = 4; /* Default of ADCRANGE = 0 */ 567 if (data->gain != 1 && data->gain != 4) { 568 dev_err(dev, "invalid shunt gain value %u\n", data->gain); 569 return -EINVAL; 570 } 571 572 /* Setup CONFIG register */ 573 config = INA238_CONFIG_DEFAULT; 574 if (data->gain == 1) 575 config |= INA238_CONFIG_ADCRANGE; /* ADCRANGE = 1 is /1 */ 576 ret = regmap_write(data->regmap, INA238_CONFIG, config); 577 if (ret < 0) { 578 dev_err(dev, "error configuring the device: %d\n", ret); 579 return -ENODEV; 580 } 581 582 /* Setup ADC_CONFIG register */ 583 ret = regmap_write(data->regmap, INA238_ADC_CONFIG, 584 INA238_ADC_CONFIG_DEFAULT); 585 if (ret < 0) { 586 dev_err(dev, "error configuring the device: %d\n", ret); 587 return -ENODEV; 588 } 589 590 /* Setup SHUNT_CALIBRATION register with fixed value */ 591 ret = regmap_write(data->regmap, INA238_SHUNT_CALIBRATION, 592 INA238_CALIBRATION_VALUE); 593 if (ret < 0) { 594 dev_err(dev, "error configuring the device: %d\n", ret); 595 return -ENODEV; 596 } 597 598 /* Setup alert/alarm configuration */ 599 ret = regmap_write(data->regmap, INA238_DIAG_ALERT, 600 INA238_DIAG_ALERT_DEFAULT); 601 if (ret < 0) { 602 dev_err(dev, "error configuring the device: %d\n", ret); 603 return -ENODEV; 604 } 605 606 hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data, 607 &ina238_chip_info, 608 NULL); 609 if (IS_ERR(hwmon_dev)) 610 return PTR_ERR(hwmon_dev); 611 612 dev_info(dev, "power monitor %s (Rshunt = %u uOhm, gain = %u)\n", 613 client->name, data->rshunt, data->gain); 614 615 return 0; 616 } 617 618 static const struct i2c_device_id ina238_id[] = { 619 { "ina238", 0 }, 620 { } 621 }; 622 MODULE_DEVICE_TABLE(i2c, ina238_id); 623 624 static const struct of_device_id __maybe_unused ina238_of_match[] = { 625 { .compatible = "ti,ina237" }, 626 { .compatible = "ti,ina238" }, 627 { }, 628 }; 629 MODULE_DEVICE_TABLE(of, ina238_of_match); 630 631 static struct i2c_driver ina238_driver = { 632 .class = I2C_CLASS_HWMON, 633 .driver = { 634 .name = "ina238", 635 .of_match_table = of_match_ptr(ina238_of_match), 636 }, 637 .probe = ina238_probe, 638 .id_table = ina238_id, 639 }; 640 641 module_i2c_driver(ina238_driver); 642 643 MODULE_AUTHOR("Nathan Rossi <nathan.rossi@digi.com>"); 644 MODULE_DESCRIPTION("ina238 driver"); 645 MODULE_LICENSE("GPL"); 646