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
  30 #include <linux/platform_data/ntc_thermistor.h>
  31
  32 #include <linux/hwmon.h>
  33 #include <linux/hwmon-sysfs.h>
  34
  35 struct ntc_compensation {
  36         int             temp_C;
  37         unsigned int    ohm;
  38 };
  39
  40 /*
  41  * A compensation table should be sorted by the values of .ohm
  42  * in descending order.
  43  * The following compensation tables are from the specification of Murata NTC
  44  * Thermistors Datasheet
  45  */
  46 static const struct ntc_compensation ncpXXwb473[] = {
  47         { .temp_C       = -40, .ohm     = 1747920 },
  48         { .temp_C       = -35, .ohm     = 1245428 },
  49         { .temp_C       = -30, .ohm     = 898485 },
  50         { .temp_C       = -25, .ohm     = 655802 },
  51         { .temp_C       = -20, .ohm     = 483954 },
  52         { .temp_C       = -15, .ohm     = 360850 },
  53         { .temp_C       = -10, .ohm     = 271697 },
  54         { .temp_C       = -5, .ohm      = 206463 },
  55         { .temp_C       = 0, .ohm       = 158214 },
  56         { .temp_C       = 5, .ohm       = 122259 },
  57         { .temp_C       = 10, .ohm      = 95227 },
  58         { .temp_C       = 15, .ohm      = 74730 },
  59         { .temp_C       = 20, .ohm      = 59065 },
  60         { .temp_C       = 25, .ohm      = 47000 },
  61         { .temp_C       = 30, .ohm      = 37643 },
  62         { .temp_C       = 35, .ohm      = 30334 },
  63         { .temp_C       = 40, .ohm      = 24591 },
  64         { .temp_C       = 45, .ohm      = 20048 },
  65         { .temp_C       = 50, .ohm      = 16433 },
  66         { .temp_C       = 55, .ohm      = 13539 },
  67         { .temp_C       = 60, .ohm      = 11209 },
  68         { .temp_C       = 65, .ohm      = 9328 },
  69         { .temp_C       = 70, .ohm      = 7798 },
  70         { .temp_C       = 75, .ohm      = 6544 },
  71         { .temp_C       = 80, .ohm      = 5518 },
  72         { .temp_C       = 85, .ohm      = 4674 },
  73         { .temp_C       = 90, .ohm      = 3972 },
  74         { .temp_C       = 95, .ohm      = 3388 },
  75         { .temp_C       = 100, .ohm     = 2902 },
  76         { .temp_C       = 105, .ohm     = 2494 },
  77         { .temp_C       = 110, .ohm     = 2150 },
  78         { .temp_C       = 115, .ohm     = 1860 },
  79         { .temp_C       = 120, .ohm     = 1615 },
  80         { .temp_C       = 125, .ohm     = 1406 },
  81 };
  82 static const struct ntc_compensation ncpXXwl333[] = {
  83         { .temp_C       = -40, .ohm     = 1610154 },
  84         { .temp_C       = -35, .ohm     = 1130850 },
  85         { .temp_C       = -30, .ohm     = 802609 },
  86         { .temp_C       = -25, .ohm     = 575385 },
  87         { .temp_C       = -20, .ohm     = 416464 },
  88         { .temp_C       = -15, .ohm     = 304219 },
  89         { .temp_C       = -10, .ohm     = 224193 },
  90         { .temp_C       = -5, .ohm      = 166623 },
  91         { .temp_C       = 0, .ohm       = 124850 },
  92         { .temp_C       = 5, .ohm       = 94287 },
  93         { .temp_C       = 10, .ohm      = 71747 },
  94         { .temp_C       = 15, .ohm      = 54996 },
  95         { .temp_C       = 20, .ohm      = 42455 },
  96         { .temp_C       = 25, .ohm      = 33000 },
  97         { .temp_C       = 30, .ohm      = 25822 },
  98         { .temp_C       = 35, .ohm      = 20335 },
  99         { .temp_C       = 40, .ohm      = 16115 },
 100         { .temp_C       = 45, .ohm      = 12849 },
 101         { .temp_C       = 50, .ohm      = 10306 },
 102         { .temp_C       = 55, .ohm      = 8314 },
 103         { .temp_C       = 60, .ohm      = 6746 },
 104         { .temp_C       = 65, .ohm      = 5503 },
 105         { .temp_C       = 70, .ohm      = 4513 },
 106         { .temp_C       = 75, .ohm      = 3721 },
 107         { .temp_C       = 80, .ohm      = 3084 },
 108         { .temp_C       = 85, .ohm      = 2569 },
 109         { .temp_C       = 90, .ohm      = 2151 },
 110         { .temp_C       = 95, .ohm      = 1809 },
 111         { .temp_C       = 100, .ohm     = 1529 },
 112         { .temp_C       = 105, .ohm     = 1299 },
 113         { .temp_C       = 110, .ohm     = 1108 },
 114         { .temp_C       = 115, .ohm     = 949 },
 115         { .temp_C       = 120, .ohm     = 817 },
 116         { .temp_C       = 125, .ohm     = 707 },
 117 };
 118
 119 struct ntc_data {
 120         struct device *hwmon_dev;
 121         struct ntc_thermistor_platform_data *pdata;
 122         const struct ntc_compensation *comp;
 123         struct device *dev;
 124         int n_comp;
 125         char name[PLATFORM_NAME_SIZE];
 126 };
 127
 128 static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
 129 {
 130         if (divisor == 0 && dividend == 0)
 131                 return 0;
 132         if (divisor == 0)
 133                 return UINT_MAX;
 134         return div64_u64(dividend, divisor);
 135 }
 136
 137 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uV)
 138 {
 139         struct ntc_thermistor_platform_data *pdata = data->pdata;
 140         u64 mV = uV / 1000;
 141         u64 pmV = pdata->pullup_uV / 1000;
 142         u64 N, puO, pdO;
 143         puO = pdata->pullup_ohm;
 144         pdO = pdata->pulldown_ohm;
 145
 146         if (mV == 0) {
 147                 if (pdata->connect == NTC_CONNECTED_POSITIVE)
 148                         return INT_MAX;
 149                 return 0;
 150         }
 151         if (mV >= pmV)
 152                 return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
 153                         0 : INT_MAX;
 154
 155         if (pdata->connect == NTC_CONNECTED_POSITIVE && puO == 0)
 156                 N = div64_u64_safe(pdO * (pmV - mV), mV);
 157         else if (pdata->connect == NTC_CONNECTED_GROUND && pdO == 0)
 158                 N = div64_u64_safe(puO * mV, pmV - mV);
 159         else if (pdata->connect == NTC_CONNECTED_POSITIVE)
 160                 N = div64_u64_safe(pdO * puO * (pmV - mV),
 161                                 puO * mV - pdO * (pmV - mV));
 162         else
 163                 N = div64_u64_safe(pdO * puO * mV, pdO * (pmV - mV) - puO * mV);
 164
 165         if (N > INT_MAX)
 166                 N = INT_MAX;
 167         return N;
 168 }
 169
 170 static void lookup_comp(struct ntc_data *data, unsigned int ohm,
 171                         int *i_low, int *i_high)
 172 {
 173         int start, end, mid;
 174
 175         /*
 176          * Handle special cases: Resistance is higher than or equal to
 177          * resistance in first table entry, or resistance is lower or equal
 178          * to resistance in last table entry.
 179          * In these cases, return i_low == i_high, either pointing to the
 180          * beginning or to the end of the table depending on the condition.
 181          */
 182         if (ohm >= data->comp[0].ohm) {
 183                 *i_low = 0;
 184                 *i_high = 0;
 185                 return;
 186         }
 187         if (ohm <= data->comp[data->n_comp - 1].ohm) {
 188                 *i_low = data->n_comp - 1;
 189                 *i_high = data->n_comp - 1;
 190                 return;
 191         }
 192
 193         /* Do a binary search on compensation table */
 194         start = 0;
 195         end = data->n_comp;
 196         while (start < end) {
 197                 mid = start + (end - start) / 2;
 198                 /*
 199                  * start <= mid < end
 200                  * data->comp[start].ohm > ohm >= data->comp[end].ohm
 201                  *
 202                  * We could check for "ohm == data->comp[mid].ohm" here, but
 203                  * that is a quite unlikely condition, and we would have to
 204                  * check again after updating start. Check it at the end instead
 205                  * for simplicity.
 206                  */
 207                 if (ohm >= data->comp[mid].ohm) {
 208                         end = mid;
 209                 } else {
 210                         start = mid + 1;
 211                         /*
 212                          * ohm >= data->comp[start].ohm might be true here,
 213                          * since we set start to mid + 1. In that case, we are
 214                          * done. We could keep going, but the condition is quite
 215                          * likely to occur, so it is worth checking for it.
 216                          */
 217                         if (ohm >= data->comp[start].ohm)
 218                                 end = start;
 219                 }
 220                 /*
 221                  * start <= end
 222                  * data->comp[start].ohm >= ohm >= data->comp[end].ohm
 223                  */
 224         }
 225         /*
 226          * start == end
 227          * ohm >= data->comp[end].ohm
 228          */
 229         *i_low = end;
 230         if (ohm == data->comp[end].ohm)
 231                 *i_high = end;
 232         else
 233                 *i_high = end - 1;
 234 }
 235
 236 static int get_temp_mC(struct ntc_data *data, unsigned int ohm)
 237 {
 238         int low, high;
 239         int temp;
 240
 241         lookup_comp(data, ohm, &low, &high);
 242         if (low == high) {
 243                 /* Unable to use linear approximation */
 244                 temp = data->comp[low].temp_C * 1000;
 245         } else {
 246                 temp = data->comp[low].temp_C * 1000 +
 247                         ((data->comp[high].temp_C - data->comp[low].temp_C) *
 248                          1000 * ((int)ohm - (int)data->comp[low].ohm)) /
 249                         ((int)data->comp[high].ohm - (int)data->comp[low].ohm);
 250         }
 251         return temp;
 252 }
 253
 254 static int ntc_thermistor_get_ohm(struct ntc_data *data)
 255 {
 256         int read_uV;
 257
 258         if (data->pdata->read_ohm)
 259                 return data->pdata->read_ohm();
 260
 261         if (data->pdata->read_uV) {
 262                 read_uV = data->pdata->read_uV();
 263                 if (read_uV < 0)
 264                         return read_uV;
 265                 return get_ohm_of_thermistor(data, read_uV);
 266         }
 267         return -EINVAL;
 268 }
 269
 270 static ssize_t ntc_show_name(struct device *dev,
 271                 struct device_attribute *attr, char *buf)
 272 {
 273         struct ntc_data *data = dev_get_drvdata(dev);
 274
 275         return sprintf(buf, "%s\n", data->name);
 276 }
 277
 278 static ssize_t ntc_show_type(struct device *dev,
 279                 struct device_attribute *attr, char *buf)
 280 {
 281         return sprintf(buf, "4\n");
 282 }
 283
 284 static ssize_t ntc_show_temp(struct device *dev,
 285                 struct device_attribute *attr, char *buf)
 286 {
 287         struct ntc_data *data = dev_get_drvdata(dev);
 288         int ohm;
 289
 290         ohm = ntc_thermistor_get_ohm(data);
 291         if (ohm < 0)
 292                 return ohm;
 293
 294         return sprintf(buf, "%d\n", get_temp_mC(data, ohm));
 295 }
 296
 297 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0);
 298 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0);
 299 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL);
 300
 301 static struct attribute *ntc_attributes[] = {
 302         &dev_attr_name.attr,
 303         &sensor_dev_attr_temp1_type.dev_attr.attr,
 304         &sensor_dev_attr_temp1_input.dev_attr.attr,
 305         NULL,
 306 };
 307
 308 static const struct attribute_group ntc_attr_group = {
 309         .attrs = ntc_attributes,
 310 };
 311
 312 static int ntc_thermistor_probe(struct platform_device *pdev)
 313 {
 314         struct ntc_data *data;
 315         struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data;
 316         int ret = 0;
 317
 318         if (!pdata) {
 319                 dev_err(&pdev->dev, "No platform init data supplied.\n");
 320                 return -ENODEV;
 321         }
 322
 323         /* Either one of the two is required. */
 324         if (!pdata->read_uV && !pdata->read_ohm) {
 325                 dev_err(&pdev->dev,
 326                         "Both read_uV and read_ohm missing. Need either one of the two.\n");
 327                 return -EINVAL;
 328         }
 329
 330         if (pdata->read_uV && pdata->read_ohm) {
 331                 dev_warn(&pdev->dev,
 332                          "Only one of read_uV and read_ohm is needed; ignoring read_uV.\n");
 333                 pdata->read_uV = NULL;
 334         }
 335
 336         if (pdata->read_uV && (pdata->pullup_uV == 0 ||
 337                                 (pdata->pullup_ohm == 0 && pdata->connect ==
 338                                  NTC_CONNECTED_GROUND) ||
 339                                 (pdata->pulldown_ohm == 0 && pdata->connect ==
 340                                  NTC_CONNECTED_POSITIVE) ||
 341                                 (pdata->connect != NTC_CONNECTED_POSITIVE &&
 342                                  pdata->connect != NTC_CONNECTED_GROUND))) {
 343                 dev_err(&pdev->dev,
 344                         "Required data to use read_uV not supplied.\n");
 345                 return -EINVAL;
 346         }
 347
 348         data = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL);
 349         if (!data)
 350                 return -ENOMEM;
 351
 352         data->dev = &pdev->dev;
 353         data->pdata = pdata;
 354         strlcpy(data->name, pdev->id_entry->name, sizeof(data->name));
 355
 356         switch (pdev->id_entry->driver_data) {
 357         case TYPE_NCPXXWB473:
 358                 data->comp = ncpXXwb473;
 359                 data->n_comp = ARRAY_SIZE(ncpXXwb473);
 360                 break;
 361         case TYPE_NCPXXWL333:
 362                 data->comp = ncpXXwl333;
 363                 data->n_comp = ARRAY_SIZE(ncpXXwl333);
 364                 break;
 365         default:
 366                 dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
 367                                 pdev->id_entry->driver_data,
 368                                 pdev->id_entry->name);
 369                 return -EINVAL;
 370         }
 371
 372         platform_set_drvdata(pdev, data);
 373
 374         ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group);
 375         if (ret) {
 376                 dev_err(data->dev, "unable to create sysfs files\n");
 377                 return ret;
 378         }
 379
 380         data->hwmon_dev = hwmon_device_register(data->dev);
 381         if (IS_ERR(data->hwmon_dev)) {
 382                 dev_err(data->dev, "unable to register as hwmon device.\n");
 383                 ret = PTR_ERR(data->hwmon_dev);
 384                 goto err_after_sysfs;
 385         }
 386
 387         dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
 388                         pdev->name, pdev->id, pdev->id_entry->name,
 389                         pdev->id_entry->driver_data);
 390         return 0;
 391 err_after_sysfs:
 392         sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 393         return ret;
 394 }
 395
 396 static int ntc_thermistor_remove(struct platform_device *pdev)
 397 {
 398         struct ntc_data *data = platform_get_drvdata(pdev);
 399
 400         hwmon_device_unregister(data->hwmon_dev);
 401         sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 402         platform_set_drvdata(pdev, NULL);
 403
 404         return 0;
 405 }
 406
 407 static const struct platform_device_id ntc_thermistor_id[] = {
 408         { "ncp15wb473", TYPE_NCPXXWB473 },
 409         { "ncp18wb473", TYPE_NCPXXWB473 },
 410         { "ncp21wb473", TYPE_NCPXXWB473 },
 411         { "ncp03wb473", TYPE_NCPXXWB473 },
 412         { "ncp15wl333", TYPE_NCPXXWL333 },
 413         { },
 414 };
 415
 416 static struct platform_driver ntc_thermistor_driver = {
 417         .driver = {
 418                 .name = "ntc-thermistor",
 419                 .owner = THIS_MODULE,
 420         },
 421         .probe = ntc_thermistor_probe,
 422         .remove = ntc_thermistor_remove,
 423         .id_table = ntc_thermistor_id,
 424 };
 425
 426 module_platform_driver(ntc_thermistor_driver);
 427
 428 MODULE_DESCRIPTION("NTC Thermistor Driver");
 429 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
 430 MODULE_LICENSE("GPL");
 431 MODULE_ALIAS("platform:ntc-thermistor");