drivers/hwmon/ntc_thermistor.c

   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 #include <linux/thermal.h>
  42
  43 struct ntc_compensation {
  44         int             temp_c;
  45         unsigned int    ohm;
  46 };
  47
  48 /* Order matters, ntc_match references the entries by index */
  49 static const struct platform_device_id ntc_thermistor_id[] = {
  50         { "ncp15wb473", TYPE_NCPXXWB473 },
  51         { "ncp18wb473", TYPE_NCPXXWB473 },
  52         { "ncp21wb473", TYPE_NCPXXWB473 },
  53         { "ncp03wb473", TYPE_NCPXXWB473 },
  54         { "ncp15wl333", TYPE_NCPXXWL333 },
  55         { "b57330v2103", TYPE_B57330V2103},
  56         { },
  57 };
  58
  59 /*
  60  * A compensation table should be sorted by the values of .ohm
  61  * in descending order.
  62  * The following compensation tables are from the specification of Murata NTC
  63  * Thermistors Datasheet
  64  */
  65 static const struct ntc_compensation ncpXXwb473[] = {
  66         { .temp_c       = -40, .ohm     = 1747920 },
  67         { .temp_c       = -35, .ohm     = 1245428 },
  68         { .temp_c       = -30, .ohm     = 898485 },
  69         { .temp_c       = -25, .ohm     = 655802 },
  70         { .temp_c       = -20, .ohm     = 483954 },
  71         { .temp_c       = -15, .ohm     = 360850 },
  72         { .temp_c       = -10, .ohm     = 271697 },
  73         { .temp_c       = -5, .ohm      = 206463 },
  74         { .temp_c       = 0, .ohm       = 158214 },
  75         { .temp_c       = 5, .ohm       = 122259 },
  76         { .temp_c       = 10, .ohm      = 95227 },
  77         { .temp_c       = 15, .ohm      = 74730 },
  78         { .temp_c       = 20, .ohm      = 59065 },
  79         { .temp_c       = 25, .ohm      = 47000 },
  80         { .temp_c       = 30, .ohm      = 37643 },
  81         { .temp_c       = 35, .ohm      = 30334 },
  82         { .temp_c       = 40, .ohm      = 24591 },
  83         { .temp_c       = 45, .ohm      = 20048 },
  84         { .temp_c       = 50, .ohm      = 16433 },
  85         { .temp_c       = 55, .ohm      = 13539 },
  86         { .temp_c       = 60, .ohm      = 11209 },
  87         { .temp_c       = 65, .ohm      = 9328 },
  88         { .temp_c       = 70, .ohm      = 7798 },
  89         { .temp_c       = 75, .ohm      = 6544 },
  90         { .temp_c       = 80, .ohm      = 5518 },
  91         { .temp_c       = 85, .ohm      = 4674 },
  92         { .temp_c       = 90, .ohm      = 3972 },
  93         { .temp_c       = 95, .ohm      = 3388 },
  94         { .temp_c       = 100, .ohm     = 2902 },
  95         { .temp_c       = 105, .ohm     = 2494 },
  96         { .temp_c       = 110, .ohm     = 2150 },
  97         { .temp_c       = 115, .ohm     = 1860 },
  98         { .temp_c       = 120, .ohm     = 1615 },
  99         { .temp_c       = 125, .ohm     = 1406 },
 100 };
 101 static const struct ntc_compensation ncpXXwl333[] = {
 102         { .temp_c       = -40, .ohm     = 1610154 },
 103         { .temp_c       = -35, .ohm     = 1130850 },
 104         { .temp_c       = -30, .ohm     = 802609 },
 105         { .temp_c       = -25, .ohm     = 575385 },
 106         { .temp_c       = -20, .ohm     = 416464 },
 107         { .temp_c       = -15, .ohm     = 304219 },
 108         { .temp_c       = -10, .ohm     = 224193 },
 109         { .temp_c       = -5, .ohm      = 166623 },
 110         { .temp_c       = 0, .ohm       = 124850 },
 111         { .temp_c       = 5, .ohm       = 94287 },
 112         { .temp_c       = 10, .ohm      = 71747 },
 113         { .temp_c       = 15, .ohm      = 54996 },
 114         { .temp_c       = 20, .ohm      = 42455 },
 115         { .temp_c       = 25, .ohm      = 33000 },
 116         { .temp_c       = 30, .ohm      = 25822 },
 117         { .temp_c       = 35, .ohm      = 20335 },
 118         { .temp_c       = 40, .ohm      = 16115 },
 119         { .temp_c       = 45, .ohm      = 12849 },
 120         { .temp_c       = 50, .ohm      = 10306 },
 121         { .temp_c       = 55, .ohm      = 8314 },
 122         { .temp_c       = 60, .ohm      = 6746 },
 123         { .temp_c       = 65, .ohm      = 5503 },
 124         { .temp_c       = 70, .ohm      = 4513 },
 125         { .temp_c       = 75, .ohm      = 3721 },
 126         { .temp_c       = 80, .ohm      = 3084 },
 127         { .temp_c       = 85, .ohm      = 2569 },
 128         { .temp_c       = 90, .ohm      = 2151 },
 129         { .temp_c       = 95, .ohm      = 1809 },
 130         { .temp_c       = 100, .ohm     = 1529 },
 131         { .temp_c       = 105, .ohm     = 1299 },
 132         { .temp_c       = 110, .ohm     = 1108 },
 133         { .temp_c       = 115, .ohm     = 949 },
 134         { .temp_c       = 120, .ohm     = 817 },
 135         { .temp_c       = 125, .ohm     = 707 },
 136 };
 137
 138 /*
 139  * The following compensation table is from the specification of EPCOS NTC
 140  * Thermistors Datasheet
 141  */
 142 static const struct ntc_compensation b57330v2103[] = {
 143         { .temp_c       = -40, .ohm     = 190030 },
 144         { .temp_c       = -35, .ohm     = 145360 },
 145         { .temp_c       = -30, .ohm     = 112060 },
 146         { .temp_c       = -25, .ohm     = 87041 },
 147         { .temp_c       = -20, .ohm     = 68104 },
 148         { .temp_c       = -15, .ohm     = 53665 },
 149         { .temp_c       = -10, .ohm     = 42576 },
 150         { .temp_c       = -5, .ohm      = 34001 },
 151         { .temp_c       = 0, .ohm       = 27326 },
 152         { .temp_c       = 5, .ohm       = 22096 },
 153         { .temp_c       = 10, .ohm      = 17973 },
 154         { .temp_c       = 15, .ohm      = 14703 },
 155         { .temp_c       = 20, .ohm      = 12090 },
 156         { .temp_c       = 25, .ohm      = 10000 },
 157         { .temp_c       = 30, .ohm      = 8311 },
 158         { .temp_c       = 35, .ohm      = 6941 },
 159         { .temp_c       = 40, .ohm      = 5825 },
 160         { .temp_c       = 45, .ohm      = 4911 },
 161         { .temp_c       = 50, .ohm      = 4158 },
 162         { .temp_c       = 55, .ohm      = 3536 },
 163         { .temp_c       = 60, .ohm      = 3019 },
 164         { .temp_c       = 65, .ohm      = 2588 },
 165         { .temp_c       = 70, .ohm      = 2227 },
 166         { .temp_c       = 75, .ohm      = 1924 },
 167         { .temp_c       = 80, .ohm      = 1668 },
 168         { .temp_c       = 85, .ohm      = 1451 },
 169         { .temp_c       = 90, .ohm      = 1266 },
 170         { .temp_c       = 95, .ohm      = 1108 },
 171         { .temp_c       = 100, .ohm     = 973 },
 172         { .temp_c       = 105, .ohm     = 857 },
 173         { .temp_c       = 110, .ohm     = 757 },
 174         { .temp_c       = 115, .ohm     = 671 },
 175         { .temp_c       = 120, .ohm     = 596 },
 176         { .temp_c       = 125, .ohm     = 531 },
 177 };
 178
 179 struct ntc_data {
 180         struct device *hwmon_dev;
 181         struct ntc_thermistor_platform_data *pdata;
 182         const struct ntc_compensation *comp;
 183         struct device *dev;
 184         int n_comp;
 185         char name[PLATFORM_NAME_SIZE];
 186         struct thermal_zone_device *tz;
 187 };
 188
 189 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO)
 190 static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
 191 {
 192         struct iio_channel *channel = pdata->chan;
 193         s64 result;
 194         int val, ret;
 195
 196         ret = iio_read_channel_raw(channel, &val);
 197         if (ret < 0) {
 198                 pr_err("read channel() error: %d\n", ret);
 199                 return ret;
 200         }
 201
 202         /* unit: mV */
 203         result = pdata->pullup_uv * (s64) val;
 204         result >>= 12;
 205
 206         return (int)result;
 207 }
 208
 209 static const struct of_device_id ntc_match[] = {
 210         { .compatible = "murata,ncp15wb473",
 211                 .data = &ntc_thermistor_id[0] },
 212         { .compatible = "murata,ncp18wb473",
 213                 .data = &ntc_thermistor_id[1] },
 214         { .compatible = "murata,ncp21wb473",
 215                 .data = &ntc_thermistor_id[2] },
 216         { .compatible = "murata,ncp03wb473",
 217                 .data = &ntc_thermistor_id[3] },
 218         { .compatible = "murata,ncp15wl333",
 219                 .data = &ntc_thermistor_id[4] },
 220         { .compatible = "epcos,b57330v2103",
 221                 .data = &ntc_thermistor_id[5]},
 222
 223         /* Usage of vendor name "ntc" is deprecated */
 224         { .compatible = "ntc,ncp15wb473",
 225                 .data = &ntc_thermistor_id[0] },
 226         { .compatible = "ntc,ncp18wb473",
 227                 .data = &ntc_thermistor_id[1] },
 228         { .compatible = "ntc,ncp21wb473",
 229                 .data = &ntc_thermistor_id[2] },
 230         { .compatible = "ntc,ncp03wb473",
 231                 .data = &ntc_thermistor_id[3] },
 232         { .compatible = "ntc,ncp15wl333",
 233                 .data = &ntc_thermistor_id[4] },
 234         { },
 235 };
 236 MODULE_DEVICE_TABLE(of, ntc_match);
 237
 238 static struct ntc_thermistor_platform_data *
 239 ntc_thermistor_parse_dt(struct platform_device *pdev)
 240 {
 241         struct iio_channel *chan;
 242         struct device_node *np = pdev->dev.of_node;
 243         struct ntc_thermistor_platform_data *pdata;
 244
 245         if (!np)
 246                 return NULL;
 247
 248         pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
 249         if (!pdata)
 250                 return ERR_PTR(-ENOMEM);
 251
 252         chan = iio_channel_get(&pdev->dev, NULL);
 253         if (IS_ERR(chan))
 254                 return ERR_CAST(chan);
 255
 256         if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv))
 257                 return ERR_PTR(-ENODEV);
 258         if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm))
 259                 return ERR_PTR(-ENODEV);
 260         if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm))
 261                 return ERR_PTR(-ENODEV);
 262
 263         if (of_find_property(np, "connected-positive", NULL))
 264                 pdata->connect = NTC_CONNECTED_POSITIVE;
 265         else /* status change should be possible if not always on. */
 266                 pdata->connect = NTC_CONNECTED_GROUND;
 267
 268         pdata->chan = chan;
 269         pdata->read_uv = ntc_adc_iio_read;
 270
 271         return pdata;
 272 }
 273 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
 274 {
 275         if (pdata->chan)
 276                 iio_channel_release(pdata->chan);
 277 }
 278 #else
 279 static struct ntc_thermistor_platform_data *
 280 ntc_thermistor_parse_dt(struct platform_device *pdev)
 281 {
 282         return NULL;
 283 }
 284
 285 #define ntc_match       NULL
 286
 287 static void ntc_iio_channel_release(struct ntc_thermistor_platform_data *pdata)
 288 { }
 289 #endif
 290
 291 static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
 292 {
 293         if (divisor == 0 && dividend == 0)
 294                 return 0;
 295         if (divisor == 0)
 296                 return UINT_MAX;
 297         return div64_u64(dividend, divisor);
 298 }
 299
 300 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv)
 301 {
 302         struct ntc_thermistor_platform_data *pdata = data->pdata;
 303         u64 mv = uv / 1000;
 304         u64 pmv = pdata->pullup_uv / 1000;
 305         u64 n, puo, pdo;
 306         puo = pdata->pullup_ohm;
 307         pdo = pdata->pulldown_ohm;
 308
 309         if (mv == 0) {
 310                 if (pdata->connect == NTC_CONNECTED_POSITIVE)
 311                         return INT_MAX;
 312                 return 0;
 313         }
 314         if (mv >= pmv)
 315                 return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
 316                         0 : INT_MAX;
 317
 318         if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0)
 319                 n = div64_u64_safe(pdo * (pmv - mv), mv);
 320         else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0)
 321                 n = div64_u64_safe(puo * mv, pmv - mv);
 322         else if (pdata->connect == NTC_CONNECTED_POSITIVE)
 323                 n = div64_u64_safe(pdo * puo * (pmv - mv),
 324                                 puo * mv - pdo * (pmv - mv));
 325         else
 326                 n = div64_u64_safe(pdo * puo * mv, pdo * (pmv - mv) - puo * mv);
 327
 328         if (n > INT_MAX)
 329                 n = INT_MAX;
 330         return n;
 331 }
 332
 333 static void lookup_comp(struct ntc_data *data, unsigned int ohm,
 334                         int *i_low, int *i_high)
 335 {
 336         int start, end, mid;
 337
 338         /*
 339          * Handle special cases: Resistance is higher than or equal to
 340          * resistance in first table entry, or resistance is lower or equal
 341          * to resistance in last table entry.
 342          * In these cases, return i_low == i_high, either pointing to the
 343          * beginning or to the end of the table depending on the condition.
 344          */
 345         if (ohm >= data->comp[0].ohm) {
 346                 *i_low = 0;
 347                 *i_high = 0;
 348                 return;
 349         }
 350         if (ohm <= data->comp[data->n_comp - 1].ohm) {
 351                 *i_low = data->n_comp - 1;
 352                 *i_high = data->n_comp - 1;
 353                 return;
 354         }
 355
 356         /* Do a binary search on compensation table */
 357         start = 0;
 358         end = data->n_comp;
 359         while (start < end) {
 360                 mid = start + (end - start) / 2;
 361                 /*
 362                  * start <= mid < end
 363                  * data->comp[start].ohm > ohm >= data->comp[end].ohm
 364                  *
 365                  * We could check for "ohm == data->comp[mid].ohm" here, but
 366                  * that is a quite unlikely condition, and we would have to
 367                  * check again after updating start. Check it at the end instead
 368                  * for simplicity.
 369                  */
 370                 if (ohm >= data->comp[mid].ohm) {
 371                         end = mid;
 372                 } else {
 373                         start = mid + 1;
 374                         /*
 375                          * ohm >= data->comp[start].ohm might be true here,
 376                          * since we set start to mid + 1. In that case, we are
 377                          * done. We could keep going, but the condition is quite
 378                          * likely to occur, so it is worth checking for it.
 379                          */
 380                         if (ohm >= data->comp[start].ohm)
 381                                 end = start;
 382                 }
 383                 /*
 384                  * start <= end
 385                  * data->comp[start].ohm >= ohm >= data->comp[end].ohm
 386                  */
 387         }
 388         /*
 389          * start == end
 390          * ohm >= data->comp[end].ohm
 391          */
 392         *i_low = end;
 393         if (ohm == data->comp[end].ohm)
 394                 *i_high = end;
 395         else
 396                 *i_high = end - 1;
 397 }
 398
 399 static int get_temp_mc(struct ntc_data *data, unsigned int ohm)
 400 {
 401         int low, high;
 402         int temp;
 403
 404         lookup_comp(data, ohm, &low, &high);
 405         if (low == high) {
 406                 /* Unable to use linear approximation */
 407                 temp = data->comp[low].temp_c * 1000;
 408         } else {
 409                 temp = data->comp[low].temp_c * 1000 +
 410                         ((data->comp[high].temp_c - data->comp[low].temp_c) *
 411                          1000 * ((int)ohm - (int)data->comp[low].ohm)) /
 412                         ((int)data->comp[high].ohm - (int)data->comp[low].ohm);
 413         }
 414         return temp;
 415 }
 416
 417 static int ntc_thermistor_get_ohm(struct ntc_data *data)
 418 {
 419         int read_uv;
 420
 421         if (data->pdata->read_ohm)
 422                 return data->pdata->read_ohm();
 423
 424         if (data->pdata->read_uv) {
 425                 read_uv = data->pdata->read_uv(data->pdata);
 426                 if (read_uv < 0)
 427                         return read_uv;
 428                 return get_ohm_of_thermistor(data, read_uv);
 429         }
 430         return -EINVAL;
 431 }
 432
 433 static int ntc_read_temp(void *dev, long *temp)
 434 {
 435         struct ntc_data *data = dev_get_drvdata(dev);
 436         int ohm;
 437
 438         ohm = ntc_thermistor_get_ohm(data);
 439         if (ohm < 0)
 440                 return ohm;
 441
 442         *temp = get_temp_mc(data, ohm);
 443
 444         return 0;
 445 }
 446
 447 static ssize_t ntc_show_name(struct device *dev,
 448                 struct device_attribute *attr, char *buf)
 449 {
 450         struct ntc_data *data = dev_get_drvdata(dev);
 451
 452         return sprintf(buf, "%s\n", data->name);
 453 }
 454
 455 static ssize_t ntc_show_type(struct device *dev,
 456                 struct device_attribute *attr, char *buf)
 457 {
 458         return sprintf(buf, "4\n");
 459 }
 460
 461 static ssize_t ntc_show_temp(struct device *dev,
 462                 struct device_attribute *attr, char *buf)
 463 {
 464         struct ntc_data *data = dev_get_drvdata(dev);
 465         int ohm;
 466
 467         ohm = ntc_thermistor_get_ohm(data);
 468         if (ohm < 0)
 469                 return ohm;
 470
 471         return sprintf(buf, "%d\n", get_temp_mc(data, ohm));
 472 }
 473
 474 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0);
 475 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0);
 476 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL);
 477
 478 static struct attribute *ntc_attributes[] = {
 479         &dev_attr_name.attr,
 480         &sensor_dev_attr_temp1_type.dev_attr.attr,
 481         &sensor_dev_attr_temp1_input.dev_attr.attr,
 482         NULL,
 483 };
 484
 485 static const struct attribute_group ntc_attr_group = {
 486         .attrs = ntc_attributes,
 487 };
 488
 489 static int ntc_thermistor_probe(struct platform_device *pdev)
 490 {
 491         const struct of_device_id *of_id =
 492                         of_match_device(of_match_ptr(ntc_match), &pdev->dev);
 493         const struct platform_device_id *pdev_id;
 494         struct ntc_thermistor_platform_data *pdata;
 495         struct ntc_data *data;
 496         int ret;
 497
 498         pdata = ntc_thermistor_parse_dt(pdev);
 499         if (IS_ERR(pdata))
 500                 return PTR_ERR(pdata);
 501         else if (pdata == NULL)
 502                 pdata = dev_get_platdata(&pdev->dev);
 503
 504         if (!pdata) {
 505                 dev_err(&pdev->dev, "No platform init data supplied.\n");
 506                 return -ENODEV;
 507         }
 508
 509         /* Either one of the two is required. */
 510         if (!pdata->read_uv && !pdata->read_ohm) {
 511                 dev_err(&pdev->dev,
 512                         "Both read_uv and read_ohm missing. Need either one of the two.\n");
 513                 return -EINVAL;
 514         }
 515
 516         if (pdata->read_uv && pdata->read_ohm) {
 517                 dev_warn(&pdev->dev,
 518                          "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n");
 519                 pdata->read_uv = NULL;
 520         }
 521
 522         if (pdata->read_uv && (pdata->pullup_uv == 0 ||
 523                                 (pdata->pullup_ohm == 0 && pdata->connect ==
 524                                  NTC_CONNECTED_GROUND) ||
 525                                 (pdata->pulldown_ohm == 0 && pdata->connect ==
 526                                  NTC_CONNECTED_POSITIVE) ||
 527                                 (pdata->connect != NTC_CONNECTED_POSITIVE &&
 528                                  pdata->connect != NTC_CONNECTED_GROUND))) {
 529                 dev_err(&pdev->dev,
 530                         "Required data to use read_uv not supplied.\n");
 531                 return -EINVAL;
 532         }
 533
 534         data = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL);
 535         if (!data)
 536                 return -ENOMEM;
 537
 538         pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);
 539
 540         data->dev = &pdev->dev;
 541         data->pdata = pdata;
 542         strlcpy(data->name, pdev_id->name, sizeof(data->name));
 543
 544         switch (pdev_id->driver_data) {
 545         case TYPE_NCPXXWB473:
 546                 data->comp = ncpXXwb473;
 547                 data->n_comp = ARRAY_SIZE(ncpXXwb473);
 548                 break;
 549         case TYPE_NCPXXWL333:
 550                 data->comp = ncpXXwl333;
 551                 data->n_comp = ARRAY_SIZE(ncpXXwl333);
 552                 break;
 553         case TYPE_B57330V2103:
 554                 data->comp = b57330v2103;
 555                 data->n_comp = ARRAY_SIZE(b57330v2103);
 556                 break;
 557         default:
 558                 dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
 559                                 pdev_id->driver_data, pdev_id->name);
 560                 return -EINVAL;
 561         }
 562
 563         platform_set_drvdata(pdev, data);
 564
 565         ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group);
 566         if (ret) {
 567                 dev_err(data->dev, "unable to create sysfs files\n");
 568                 return ret;
 569         }
 570
 571         data->hwmon_dev = hwmon_device_register(data->dev);
 572         if (IS_ERR(data->hwmon_dev)) {
 573                 dev_err(data->dev, "unable to register as hwmon device.\n");
 574                 ret = PTR_ERR(data->hwmon_dev);
 575                 goto err_after_sysfs;
 576         }
 577
 578         dev_info(&pdev->dev, "Thermistor type: %s successfully probed.\n",
 579                                                                 pdev_id->name);
 580
 581         data->tz = thermal_zone_of_sensor_register(data->dev, 0, data->dev,
 582                                                 ntc_read_temp, NULL);
 583         if (IS_ERR(data->tz)) {
 584                 dev_dbg(&pdev->dev, "Failed to register to thermal fw.\n");
 585                 data->tz = NULL;
 586         }
 587
 588         return 0;
 589 err_after_sysfs:
 590         sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 591         ntc_iio_channel_release(pdata);
 592         return ret;
 593 }
 594
 595 static int ntc_thermistor_remove(struct platform_device *pdev)
 596 {
 597         struct ntc_data *data = platform_get_drvdata(pdev);
 598         struct ntc_thermistor_platform_data *pdata = data->pdata;
 599
 600         hwmon_device_unregister(data->hwmon_dev);
 601         sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 602         ntc_iio_channel_release(pdata);
 603
 604         thermal_zone_of_sensor_unregister(data->dev, data->tz);
 605
 606         return 0;
 607 }
 608
 609 static struct platform_driver ntc_thermistor_driver = {
 610         .driver = {
 611                 .name = "ntc-thermistor",
 612                 .owner = THIS_MODULE,
 613                 .of_match_table = of_match_ptr(ntc_match),
 614         },
 615         .probe = ntc_thermistor_probe,
 616         .remove = ntc_thermistor_remove,
 617         .id_table = ntc_thermistor_id,
 618 };
 619
 620 module_platform_driver(ntc_thermistor_driver);
 621
 622 MODULE_DESCRIPTION("NTC Thermistor Driver");
 623 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
 624 MODULE_LICENSE("GPL");
 625 MODULE_ALIAS("platform:ntc-thermistor");