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 = "ntc,ncp15wb473", 167 .data = &ntc_thermistor_id[0] }, 168 { .compatible = "ntc,ncp18wb473", 169 .data = &ntc_thermistor_id[1] }, 170 { .compatible = "ntc,ncp21wb473", 171 .data = &ntc_thermistor_id[2] }, 172 { .compatible = "ntc,ncp03wb473", 173 .data = &ntc_thermistor_id[3] }, 174 { .compatible = "ntc,ncp15wl333", 175 .data = &ntc_thermistor_id[4] }, 176 { }, 177 }; 178 MODULE_DEVICE_TABLE(of, ntc_match); 179 180 static struct ntc_thermistor_platform_data * 181 ntc_thermistor_parse_dt(struct platform_device *pdev) 182 { 183 struct iio_channel *chan; 184 struct device_node *np = pdev->dev.of_node; 185 struct ntc_thermistor_platform_data *pdata; 186 187 if (!np) 188 return NULL; 189 190 pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); 191 if (!pdata) 192 return ERR_PTR(-ENOMEM); 193 194 chan = iio_channel_get(&pdev->dev, NULL); 195 if (IS_ERR(chan)) 196 return ERR_CAST(chan); 197 198 if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv)) 199 return ERR_PTR(-ENODEV); 200 if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm)) 201 return ERR_PTR(-ENODEV); 202 if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm)) 203 return ERR_PTR(-ENODEV); 204 205 if (of_find_property(np, "connected-positive", NULL)) 206 pdata->connect = NTC_CONNECTED_POSITIVE; 207 else /* status change should be possible if not always on. */ 208 pdata->connect = NTC_CONNECTED_GROUND; 209 210 pdata->chan = chan; 211 pdata->read_uv = ntc_adc_iio_read; 212 213 return pdata; 214 } 215 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata) 216 { 217 if (pdata->chan) 218 iio_channel_release(pdata->chan); 219 } 220 #else 221 static struct ntc_thermistor_platform_data * 222 ntc_thermistor_parse_dt(struct platform_device *pdev) 223 { 224 return NULL; 225 } 226 227 #define ntc_match NULL 228 229 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata) 230 { } 231 #endif 232 233 static inline u64 div64_u64_safe(u64 dividend, u64 divisor) 234 { 235 if (divisor == 0 && dividend == 0) 236 return 0; 237 if (divisor == 0) 238 return UINT_MAX; 239 return div64_u64(dividend, divisor); 240 } 241 242 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv) 243 { 244 struct ntc_thermistor_platform_data *pdata = data->pdata; 245 u64 mv = uv / 1000; 246 u64 pmv = pdata->pullup_uv / 1000; 247 u64 n, puo, pdo; 248 puo = pdata->pullup_ohm; 249 pdo = pdata->pulldown_ohm; 250 251 if (mv == 0) { 252 if (pdata->connect == NTC_CONNECTED_POSITIVE) 253 return INT_MAX; 254 return 0; 255 } 256 if (mv >= pmv) 257 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 258 0 : INT_MAX; 259 260 if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0) 261 n = div64_u64_safe(pdo * (pmv - mv), mv); 262 else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0) 263 n = div64_u64_safe(puo * mv, pmv - mv); 264 else if (pdata->connect == NTC_CONNECTED_POSITIVE) 265 n = div64_u64_safe(pdo * puo * (pmv - mv), 266 puo * mv - pdo * (pmv - mv)); 267 else 268 n = div64_u64_safe(pdo * puo * mv, pdo * (pmv - mv) - puo * mv); 269 270 if (n > INT_MAX) 271 n = INT_MAX; 272 return n; 273 } 274 275 static void lookup_comp(struct ntc_data *data, unsigned int ohm, 276 int *i_low, int *i_high) 277 { 278 int start, end, mid; 279 280 /* 281 * Handle special cases: Resistance is higher than or equal to 282 * resistance in first table entry, or resistance is lower or equal 283 * to resistance in last table entry. 284 * In these cases, return i_low == i_high, either pointing to the 285 * beginning or to the end of the table depending on the condition. 286 */ 287 if (ohm >= data->comp[0].ohm) { 288 *i_low = 0; 289 *i_high = 0; 290 return; 291 } 292 if (ohm <= data->comp[data->n_comp - 1].ohm) { 293 *i_low = data->n_comp - 1; 294 *i_high = data->n_comp - 1; 295 return; 296 } 297 298 /* Do a binary search on compensation table */ 299 start = 0; 300 end = data->n_comp; 301 while (start < end) { 302 mid = start + (end - start) / 2; 303 /* 304 * start <= mid < end 305 * data->comp[start].ohm > ohm >= data->comp[end].ohm 306 * 307 * We could check for "ohm == data->comp[mid].ohm" here, but 308 * that is a quite unlikely condition, and we would have to 309 * check again after updating start. Check it at the end instead 310 * for simplicity. 311 */ 312 if (ohm >= data->comp[mid].ohm) { 313 end = mid; 314 } else { 315 start = mid + 1; 316 /* 317 * ohm >= data->comp[start].ohm might be true here, 318 * since we set start to mid + 1. In that case, we are 319 * done. We could keep going, but the condition is quite 320 * likely to occur, so it is worth checking for it. 321 */ 322 if (ohm >= data->comp[start].ohm) 323 end = start; 324 } 325 /* 326 * start <= end 327 * data->comp[start].ohm >= ohm >= data->comp[end].ohm 328 */ 329 } 330 /* 331 * start == end 332 * ohm >= data->comp[end].ohm 333 */ 334 *i_low = end; 335 if (ohm == data->comp[end].ohm) 336 *i_high = end; 337 else 338 *i_high = end - 1; 339 } 340 341 static int get_temp_mc(struct ntc_data *data, unsigned int ohm) 342 { 343 int low, high; 344 int temp; 345 346 lookup_comp(data, ohm, &low, &high); 347 if (low == high) { 348 /* Unable to use linear approximation */ 349 temp = data->comp[low].temp_c * 1000; 350 } else { 351 temp = data->comp[low].temp_c * 1000 + 352 ((data->comp[high].temp_c - data->comp[low].temp_c) * 353 1000 * ((int)ohm - (int)data->comp[low].ohm)) / 354 ((int)data->comp[high].ohm - (int)data->comp[low].ohm); 355 } 356 return temp; 357 } 358 359 static int ntc_thermistor_get_ohm(struct ntc_data *data) 360 { 361 int read_uv; 362 363 if (data->pdata->read_ohm) 364 return data->pdata->read_ohm(); 365 366 if (data->pdata->read_uv) { 367 read_uv = data->pdata->read_uv(data->pdata); 368 if (read_uv < 0) 369 return read_uv; 370 return get_ohm_of_thermistor(data, read_uv); 371 } 372 return -EINVAL; 373 } 374 375 static ssize_t ntc_show_name(struct device *dev, 376 struct device_attribute *attr, char *buf) 377 { 378 struct ntc_data *data = dev_get_drvdata(dev); 379 380 return sprintf(buf, "%s\n", data->name); 381 } 382 383 static ssize_t ntc_show_type(struct device *dev, 384 struct device_attribute *attr, char *buf) 385 { 386 return sprintf(buf, "4\n"); 387 } 388 389 static ssize_t ntc_show_temp(struct device *dev, 390 struct device_attribute *attr, char *buf) 391 { 392 struct ntc_data *data = dev_get_drvdata(dev); 393 int ohm; 394 395 ohm = ntc_thermistor_get_ohm(data); 396 if (ohm < 0) 397 return ohm; 398 399 return sprintf(buf, "%d\n", get_temp_mc(data, ohm)); 400 } 401 402 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0); 403 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0); 404 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL); 405 406 static struct attribute *ntc_attributes[] = { 407 &dev_attr_name.attr, 408 &sensor_dev_attr_temp1_type.dev_attr.attr, 409 &sensor_dev_attr_temp1_input.dev_attr.attr, 410 NULL, 411 }; 412 413 static const struct attribute_group ntc_attr_group = { 414 .attrs = ntc_attributes, 415 }; 416 417 static int ntc_thermistor_probe(struct platform_device *pdev) 418 { 419 const struct of_device_id *of_id = 420 of_match_device(of_match_ptr(ntc_match), &pdev->dev); 421 const struct platform_device_id *pdev_id; 422 struct ntc_thermistor_platform_data *pdata; 423 struct ntc_data *data; 424 int ret; 425 426 pdata = ntc_thermistor_parse_dt(pdev); 427 if (IS_ERR(pdata)) 428 return PTR_ERR(pdata); 429 else if (pdata == NULL) 430 pdata = dev_get_platdata(&pdev->dev); 431 432 if (!pdata) { 433 dev_err(&pdev->dev, "No platform init data supplied.\n"); 434 return -ENODEV; 435 } 436 437 /* Either one of the two is required. */ 438 if (!pdata->read_uv && !pdata->read_ohm) { 439 dev_err(&pdev->dev, 440 "Both read_uv and read_ohm missing. Need either one of the two.\n"); 441 return -EINVAL; 442 } 443 444 if (pdata->read_uv && pdata->read_ohm) { 445 dev_warn(&pdev->dev, 446 "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n"); 447 pdata->read_uv = NULL; 448 } 449 450 if (pdata->read_uv && (pdata->pullup_uv == 0 || 451 (pdata->pullup_ohm == 0 && pdata->connect == 452 NTC_CONNECTED_GROUND) || 453 (pdata->pulldown_ohm == 0 && pdata->connect == 454 NTC_CONNECTED_POSITIVE) || 455 (pdata->connect != NTC_CONNECTED_POSITIVE && 456 pdata->connect != NTC_CONNECTED_GROUND))) { 457 dev_err(&pdev->dev, 458 "Required data to use read_uv not supplied.\n"); 459 return -EINVAL; 460 } 461 462 data = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL); 463 if (!data) 464 return -ENOMEM; 465 466 pdev_id = of_id ? of_id->data : platform_get_device_id(pdev); 467 468 data->dev = &pdev->dev; 469 data->pdata = pdata; 470 strlcpy(data->name, pdev_id->name, sizeof(data->name)); 471 472 switch (pdev_id->driver_data) { 473 case TYPE_NCPXXWB473: 474 data->comp = ncpXXwb473; 475 data->n_comp = ARRAY_SIZE(ncpXXwb473); 476 break; 477 case TYPE_NCPXXWL333: 478 data->comp = ncpXXwl333; 479 data->n_comp = ARRAY_SIZE(ncpXXwl333); 480 break; 481 default: 482 dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n", 483 pdev_id->driver_data, pdev_id->name); 484 return -EINVAL; 485 } 486 487 platform_set_drvdata(pdev, data); 488 489 ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group); 490 if (ret) { 491 dev_err(data->dev, "unable to create sysfs files\n"); 492 return ret; 493 } 494 495 data->hwmon_dev = hwmon_device_register(data->dev); 496 if (IS_ERR(data->hwmon_dev)) { 497 dev_err(data->dev, "unable to register as hwmon device.\n"); 498 ret = PTR_ERR(data->hwmon_dev); 499 goto err_after_sysfs; 500 } 501 502 dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n", 503 pdev->name); 504 505 return 0; 506 err_after_sysfs: 507 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); 508 ntc_iio_channel_release(pdata); 509 return ret; 510 } 511 512 static int ntc_thermistor_remove(struct platform_device *pdev) 513 { 514 struct ntc_data *data = platform_get_drvdata(pdev); 515 struct ntc_thermistor_platform_data *pdata = data->pdata; 516 517 hwmon_device_unregister(data->hwmon_dev); 518 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); 519 ntc_iio_channel_release(pdata); 520 521 return 0; 522 } 523 524 static struct platform_driver ntc_thermistor_driver = { 525 .driver = { 526 .name = "ntc-thermistor", 527 .owner = THIS_MODULE, 528 .of_match_table = of_match_ptr(ntc_match), 529 }, 530 .probe = ntc_thermistor_probe, 531 .remove = ntc_thermistor_remove, 532 .id_table = ntc_thermistor_id, 533 }; 534 535 module_platform_driver(ntc_thermistor_driver); 536 537 MODULE_DESCRIPTION("NTC Thermistor Driver"); 538 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 539 MODULE_LICENSE("GPL"); 540 MODULE_ALIAS("platform:ntc-thermistor"); 541