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