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