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         { },
  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");