1 /* 2 * ntc_thermistor.c - NTC Thermistors 3 * 4 * Copyright (C) 2010 Samsung Electronics 5 * MyungJoo Ham <myungjoo.ham@samsung.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 * 21 */ 22 23 #include <linux/slab.h> 24 #include <linux/module.h> 25 #include <linux/pm_runtime.h> 26 #include <linux/math64.h> 27 #include <linux/platform_device.h> 28 #include <linux/err.h> 29 #include <linux/of.h> 30 #include <linux/of_device.h> 31 32 #include <linux/platform_data/ntc_thermistor.h> 33 34 #include <linux/iio/iio.h> 35 #include <linux/iio/machine.h> 36 #include <linux/iio/driver.h> 37 #include <linux/iio/consumer.h> 38 39 #include <linux/hwmon.h> 40 #include <linux/hwmon-sysfs.h> 41 42 struct ntc_compensation { 43 int temp_c; 44 unsigned int ohm; 45 }; 46 47 /* Order matters, ntc_match references the entries by index */ 48 static const struct platform_device_id ntc_thermistor_id[] = { 49 { "ncp15wb473", TYPE_NCPXXWB473 }, 50 { "ncp18wb473", TYPE_NCPXXWB473 }, 51 { "ncp21wb473", TYPE_NCPXXWB473 }, 52 { "ncp03wb473", TYPE_NCPXXWB473 }, 53 { "ncp15wl333", TYPE_NCPXXWL333 }, 54 { }, 55 }; 56 57 /* 58 * A compensation table should be sorted by the values of .ohm 59 * in descending order. 60 * The following compensation tables are from the specification of Murata NTC 61 * Thermistors Datasheet 62 */ 63 static const struct ntc_compensation ncpXXwb473[] = { 64 { .temp_c = -40, .ohm = 1747920 }, 65 { .temp_c = -35, .ohm = 1245428 }, 66 { .temp_c = -30, .ohm = 898485 }, 67 { .temp_c = -25, .ohm = 655802 }, 68 { .temp_c = -20, .ohm = 483954 }, 69 { .temp_c = -15, .ohm = 360850 }, 70 { .temp_c = -10, .ohm = 271697 }, 71 { .temp_c = -5, .ohm = 206463 }, 72 { .temp_c = 0, .ohm = 158214 }, 73 { .temp_c = 5, .ohm = 122259 }, 74 { .temp_c = 10, .ohm = 95227 }, 75 { .temp_c = 15, .ohm = 74730 }, 76 { .temp_c = 20, .ohm = 59065 }, 77 { .temp_c = 25, .ohm = 47000 }, 78 { .temp_c = 30, .ohm = 37643 }, 79 { .temp_c = 35, .ohm = 30334 }, 80 { .temp_c = 40, .ohm = 24591 }, 81 { .temp_c = 45, .ohm = 20048 }, 82 { .temp_c = 50, .ohm = 16433 }, 83 { .temp_c = 55, .ohm = 13539 }, 84 { .temp_c = 60, .ohm = 11209 }, 85 { .temp_c = 65, .ohm = 9328 }, 86 { .temp_c = 70, .ohm = 7798 }, 87 { .temp_c = 75, .ohm = 6544 }, 88 { .temp_c = 80, .ohm = 5518 }, 89 { .temp_c = 85, .ohm = 4674 }, 90 { .temp_c = 90, .ohm = 3972 }, 91 { .temp_c = 95, .ohm = 3388 }, 92 { .temp_c = 100, .ohm = 2902 }, 93 { .temp_c = 105, .ohm = 2494 }, 94 { .temp_c = 110, .ohm = 2150 }, 95 { .temp_c = 115, .ohm = 1860 }, 96 { .temp_c = 120, .ohm = 1615 }, 97 { .temp_c = 125, .ohm = 1406 }, 98 }; 99 static const struct ntc_compensation ncpXXwl333[] = { 100 { .temp_c = -40, .ohm = 1610154 }, 101 { .temp_c = -35, .ohm = 1130850 }, 102 { .temp_c = -30, .ohm = 802609 }, 103 { .temp_c = -25, .ohm = 575385 }, 104 { .temp_c = -20, .ohm = 416464 }, 105 { .temp_c = -15, .ohm = 304219 }, 106 { .temp_c = -10, .ohm = 224193 }, 107 { .temp_c = -5, .ohm = 166623 }, 108 { .temp_c = 0, .ohm = 124850 }, 109 { .temp_c = 5, .ohm = 94287 }, 110 { .temp_c = 10, .ohm = 71747 }, 111 { .temp_c = 15, .ohm = 54996 }, 112 { .temp_c = 20, .ohm = 42455 }, 113 { .temp_c = 25, .ohm = 33000 }, 114 { .temp_c = 30, .ohm = 25822 }, 115 { .temp_c = 35, .ohm = 20335 }, 116 { .temp_c = 40, .ohm = 16115 }, 117 { .temp_c = 45, .ohm = 12849 }, 118 { .temp_c = 50, .ohm = 10306 }, 119 { .temp_c = 55, .ohm = 8314 }, 120 { .temp_c = 60, .ohm = 6746 }, 121 { .temp_c = 65, .ohm = 5503 }, 122 { .temp_c = 70, .ohm = 4513 }, 123 { .temp_c = 75, .ohm = 3721 }, 124 { .temp_c = 80, .ohm = 3084 }, 125 { .temp_c = 85, .ohm = 2569 }, 126 { .temp_c = 90, .ohm = 2151 }, 127 { .temp_c = 95, .ohm = 1809 }, 128 { .temp_c = 100, .ohm = 1529 }, 129 { .temp_c = 105, .ohm = 1299 }, 130 { .temp_c = 110, .ohm = 1108 }, 131 { .temp_c = 115, .ohm = 949 }, 132 { .temp_c = 120, .ohm = 817 }, 133 { .temp_c = 125, .ohm = 707 }, 134 }; 135 136 struct ntc_data { 137 struct device *hwmon_dev; 138 struct ntc_thermistor_platform_data *pdata; 139 const struct ntc_compensation *comp; 140 struct device *dev; 141 int n_comp; 142 char name[PLATFORM_NAME_SIZE]; 143 }; 144 145 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO) 146 static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata) 147 { 148 struct iio_channel *channel = pdata->chan; 149 s64 result; 150 int val, ret; 151 152 ret = iio_read_channel_raw(channel, &val); 153 if (ret < 0) { 154 pr_err("read channel() error: %d\n", ret); 155 return ret; 156 } 157 158 /* unit: mV */ 159 result = pdata->pullup_uv * (s64) val; 160 result >>= 12; 161 162 return (int)result; 163 } 164 165 static const struct of_device_id ntc_match[] = { 166 { .compatible = "murata,ncp15wb473", 167 .data = &ntc_thermistor_id[0] }, 168 { .compatible = "murata,ncp18wb473", 169 .data = &ntc_thermistor_id[1] }, 170 { .compatible = "murata,ncp21wb473", 171 .data = &ntc_thermistor_id[2] }, 172 { .compatible = "murata,ncp03wb473", 173 .data = &ntc_thermistor_id[3] }, 174 { .compatible = "murata,ncp15wl333", 175 .data = &ntc_thermistor_id[4] }, 176 177 /* Usage of vendor name "ntc" is deprecated */ 178 { .compatible = "ntc,ncp15wb473", 179 .data = &ntc_thermistor_id[0] }, 180 { .compatible = "ntc,ncp18wb473", 181 .data = &ntc_thermistor_id[1] }, 182 { .compatible = "ntc,ncp21wb473", 183 .data = &ntc_thermistor_id[2] }, 184 { .compatible = "ntc,ncp03wb473", 185 .data = &ntc_thermistor_id[3] }, 186 { .compatible = "ntc,ncp15wl333", 187 .data = &ntc_thermistor_id[4] }, 188 { }, 189 }; 190 MODULE_DEVICE_TABLE(of, ntc_match); 191 192 static struct ntc_thermistor_platform_data * 193 ntc_thermistor_parse_dt(struct platform_device *pdev) 194 { 195 struct iio_channel *chan; 196 struct device_node *np = pdev->dev.of_node; 197 struct ntc_thermistor_platform_data *pdata; 198 199 if (!np) 200 return NULL; 201 202 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); 203 if (!pdata) 204 return ERR_PTR(-ENOMEM); 205 206 chan = iio_channel_get(&pdev->dev, NULL); 207 if (IS_ERR(chan)) 208 return ERR_CAST(chan); 209 210 if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv)) 211 return ERR_PTR(-ENODEV); 212 if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm)) 213 return ERR_PTR(-ENODEV); 214 if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm)) 215 return ERR_PTR(-ENODEV); 216 217 if (of_find_property(np, "connected-positive", NULL)) 218 pdata->connect = NTC_CONNECTED_POSITIVE; 219 else /* status change should be possible if not always on. */ 220 pdata->connect = NTC_CONNECTED_GROUND; 221 222 pdata->chan = chan; 223 pdata->read_uv = ntc_adc_iio_read; 224 225 return pdata; 226 } 227 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata) 228 { 229 if (pdata->chan) 230 iio_channel_release(pdata->chan); 231 } 232 #else 233 static struct ntc_thermistor_platform_data * 234 ntc_thermistor_parse_dt(struct platform_device *pdev) 235 { 236 return NULL; 237 } 238 239 #define ntc_match NULL 240 241 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata) 242 { } 243 #endif 244 245 static inline u64 div64_u64_safe(u64 dividend, u64 divisor) 246 { 247 if (divisor == 0 && dividend == 0) 248 return 0; 249 if (divisor == 0) 250 return UINT_MAX; 251 return div64_u64(dividend, divisor); 252 } 253 254 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv) 255 { 256 struct ntc_thermistor_platform_data *pdata = data->pdata; 257 u64 mv = uv / 1000; 258 u64 pmv = pdata->pullup_uv / 1000; 259 u64 n, puo, pdo; 260 puo = pdata->pullup_ohm; 261 pdo = pdata->pulldown_ohm; 262 263 if (mv == 0) { 264 if (pdata->connect == NTC_CONNECTED_POSITIVE) 265 return INT_MAX; 266 return 0; 267 } 268 if (mv >= pmv) 269 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 270 0 : INT_MAX; 271 272 if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0) 273 n = div64_u64_safe(pdo * (pmv - mv), mv); 274 else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0) 275 n = div64_u64_safe(puo * mv, pmv - mv); 276 else if (pdata->connect == NTC_CONNECTED_POSITIVE) 277 n = div64_u64_safe(pdo * puo * (pmv - mv), 278 puo * mv - pdo * (pmv - mv)); 279 else 280 n = div64_u64_safe(pdo * puo * mv, pdo * (pmv - mv) - puo * mv); 281 282 if (n > INT_MAX) 283 n = INT_MAX; 284 return n; 285 } 286 287 static void lookup_comp(struct ntc_data *data, unsigned int ohm, 288 int *i_low, int *i_high) 289 { 290 int start, end, mid; 291 292 /* 293 * Handle special cases: Resistance is higher than or equal to 294 * resistance in first table entry, or resistance is lower or equal 295 * to resistance in last table entry. 296 * In these cases, return i_low == i_high, either pointing to the 297 * beginning or to the end of the table depending on the condition. 298 */ 299 if (ohm >= data->comp[0].ohm) { 300 *i_low = 0; 301 *i_high = 0; 302 return; 303 } 304 if (ohm <= data->comp[data->n_comp - 1].ohm) { 305 *i_low = data->n_comp - 1; 306 *i_high = data->n_comp - 1; 307 return; 308 } 309 310 /* Do a binary search on compensation table */ 311 start = 0; 312 end = data->n_comp; 313 while (start < end) { 314 mid = start + (end - start) / 2; 315 /* 316 * start <= mid < end 317 * data->comp[start].ohm > ohm >= data->comp[end].ohm 318 * 319 * We could check for "ohm == data->comp[mid].ohm" here, but 320 * that is a quite unlikely condition, and we would have to 321 * check again after updating start. Check it at the end instead 322 * for simplicity. 323 */ 324 if (ohm >= data->comp[mid].ohm) { 325 end = mid; 326 } else { 327 start = mid + 1; 328 /* 329 * ohm >= data->comp[start].ohm might be true here, 330 * since we set start to mid + 1. In that case, we are 331 * done. We could keep going, but the condition is quite 332 * likely to occur, so it is worth checking for it. 333 */ 334 if (ohm >= data->comp[start].ohm) 335 end = start; 336 } 337 /* 338 * start <= end 339 * data->comp[start].ohm >= ohm >= data->comp[end].ohm 340 */ 341 } 342 /* 343 * start == end 344 * ohm >= data->comp[end].ohm 345 */ 346 *i_low = end; 347 if (ohm == data->comp[end].ohm) 348 *i_high = end; 349 else 350 *i_high = end - 1; 351 } 352 353 static int get_temp_mc(struct ntc_data *data, unsigned int ohm) 354 { 355 int low, high; 356 int temp; 357 358 lookup_comp(data, ohm, &low, &high); 359 if (low == high) { 360 /* Unable to use linear approximation */ 361 temp = data->comp[low].temp_c * 1000; 362 } else { 363 temp = data->comp[low].temp_c * 1000 + 364 ((data->comp[high].temp_c - data->comp[low].temp_c) * 365 1000 * ((int)ohm - (int)data->comp[low].ohm)) / 366 ((int)data->comp[high].ohm - (int)data->comp[low].ohm); 367 } 368 return temp; 369 } 370 371 static int ntc_thermistor_get_ohm(struct ntc_data *data) 372 { 373 int read_uv; 374 375 if (data->pdata->read_ohm) 376 return data->pdata->read_ohm(); 377 378 if (data->pdata->read_uv) { 379 read_uv = data->pdata->read_uv(data->pdata); 380 if (read_uv < 0) 381 return read_uv; 382 return get_ohm_of_thermistor(data, read_uv); 383 } 384 return -EINVAL; 385 } 386 387 static ssize_t ntc_show_name(struct device *dev, 388 struct device_attribute *attr, char *buf) 389 { 390 struct ntc_data *data = dev_get_drvdata(dev); 391 392 return sprintf(buf, "%s\n", data->name); 393 } 394 395 static ssize_t ntc_show_type(struct device *dev, 396 struct device_attribute *attr, char *buf) 397 { 398 return sprintf(buf, "4\n"); 399 } 400 401 static ssize_t ntc_show_temp(struct device *dev, 402 struct device_attribute *attr, char *buf) 403 { 404 struct ntc_data *data = dev_get_drvdata(dev); 405 int ohm; 406 407 ohm = ntc_thermistor_get_ohm(data); 408 if (ohm < 0) 409 return ohm; 410 411 return sprintf(buf, "%d\n", get_temp_mc(data, ohm)); 412 } 413 414 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0); 415 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0); 416 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL); 417 418 static struct attribute *ntc_attributes[] = { 419 &dev_attr_name.attr, 420 &sensor_dev_attr_temp1_type.dev_attr.attr, 421 &sensor_dev_attr_temp1_input.dev_attr.attr, 422 NULL, 423 }; 424 425 static const struct attribute_group ntc_attr_group = { 426 .attrs = ntc_attributes, 427 }; 428 429 static int ntc_thermistor_probe(struct platform_device *pdev) 430 { 431 const struct of_device_id *of_id = 432 of_match_device(of_match_ptr(ntc_match), &pdev->dev); 433 const struct platform_device_id *pdev_id; 434 struct ntc_thermistor_platform_data *pdata; 435 struct ntc_data *data; 436 int ret; 437 438 pdata = ntc_thermistor_parse_dt(pdev); 439 if (IS_ERR(pdata)) 440 return PTR_ERR(pdata); 441 else if (pdata == NULL) 442 pdata = dev_get_platdata(&pdev->dev); 443 444 if (!pdata) { 445 dev_err(&pdev->dev, "No platform init data supplied.\n"); 446 return -ENODEV; 447 } 448 449 /* Either one of the two is required. */ 450 if (!pdata->read_uv && !pdata->read_ohm) { 451 dev_err(&pdev->dev, 452 "Both read_uv and read_ohm missing. Need either one of the two.\n"); 453 return -EINVAL; 454 } 455 456 if (pdata->read_uv && pdata->read_ohm) { 457 dev_warn(&pdev->dev, 458 "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n"); 459 pdata->read_uv = NULL; 460 } 461 462 if (pdata->read_uv && (pdata->pullup_uv == 0 || 463 (pdata->pullup_ohm == 0 && pdata->connect == 464 NTC_CONNECTED_GROUND) || 465 (pdata->pulldown_ohm == 0 && pdata->connect == 466 NTC_CONNECTED_POSITIVE) || 467 (pdata->connect != NTC_CONNECTED_POSITIVE && 468 pdata->connect != NTC_CONNECTED_GROUND))) { 469 dev_err(&pdev->dev, 470 "Required data to use read_uv not supplied.\n"); 471 return -EINVAL; 472 } 473 474 data = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL); 475 if (!data) 476 return -ENOMEM; 477 478 pdev_id = of_id ? of_id->data : platform_get_device_id(pdev); 479 480 data->dev = &pdev->dev; 481 data->pdata = pdata; 482 strlcpy(data->name, pdev_id->name, sizeof(data->name)); 483 484 switch (pdev_id->driver_data) { 485 case TYPE_NCPXXWB473: 486 data->comp = ncpXXwb473; 487 data->n_comp = ARRAY_SIZE(ncpXXwb473); 488 break; 489 case TYPE_NCPXXWL333: 490 data->comp = ncpXXwl333; 491 data->n_comp = ARRAY_SIZE(ncpXXwl333); 492 break; 493 default: 494 dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n", 495 pdev_id->driver_data, pdev_id->name); 496 return -EINVAL; 497 } 498 499 platform_set_drvdata(pdev, data); 500 501 ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group); 502 if (ret) { 503 dev_err(data->dev, "unable to create sysfs files\n"); 504 return ret; 505 } 506 507 data->hwmon_dev = hwmon_device_register(data->dev); 508 if (IS_ERR(data->hwmon_dev)) { 509 dev_err(data->dev, "unable to register as hwmon device.\n"); 510 ret = PTR_ERR(data->hwmon_dev); 511 goto err_after_sysfs; 512 } 513 514 dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n", 515 pdev_id->name); 516 517 return 0; 518 err_after_sysfs: 519 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); 520 ntc_iio_channel_release(pdata); 521 return ret; 522 } 523 524 static int ntc_thermistor_remove(struct platform_device *pdev) 525 { 526 struct ntc_data *data = platform_get_drvdata(pdev); 527 struct ntc_thermistor_platform_data *pdata = data->pdata; 528 529 hwmon_device_unregister(data->hwmon_dev); 530 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); 531 ntc_iio_channel_release(pdata); 532 533 return 0; 534 } 535 536 static struct platform_driver ntc_thermistor_driver = { 537 .driver = { 538 .name = "ntc-thermistor", 539 .owner = THIS_MODULE, 540 .of_match_table = of_match_ptr(ntc_match), 541 }, 542 .probe = ntc_thermistor_probe, 543 .remove = ntc_thermistor_remove, 544 .id_table = ntc_thermistor_id, 545 }; 546 547 module_platform_driver(ntc_thermistor_driver); 548 549 MODULE_DESCRIPTION("NTC Thermistor Driver from Murata"); 550 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 551 MODULE_LICENSE("GPL"); 552 MODULE_ALIAS("platform:ntc-thermistor"); 553