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 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         unsigned int 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 * val;
 159         result >>= 12;
 160
 161         return 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 = pdev->dev.platform_data;
 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         platform_set_drvdata(pdev, NULL);
 518
 519         return 0;
 520 }
 521
 522 static struct platform_driver ntc_thermistor_driver = {
 523         .driver = {
 524                 .name = "ntc-thermistor",
 525                 .owner = THIS_MODULE,
 526                 .of_match_table = of_match_ptr(ntc_match),
 527         },
 528         .probe = ntc_thermistor_probe,
 529         .remove = ntc_thermistor_remove,
 530         .id_table = ntc_thermistor_id,
 531 };
 532
 533 module_platform_driver(ntc_thermistor_driver);
 534
 535 MODULE_DESCRIPTION("NTC Thermistor Driver");
 536 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
 537 MODULE_LICENSE("GPL");
 538 MODULE_ALIAS("platform:ntc-thermistor");