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 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 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 unsigned int get_ohm_of_thermistor(struct ntc_data *data,
 138                 unsigned int uV)
 139 {
 140         struct ntc_thermistor_platform_data *pdata = data->pdata;
 141         u64 mV = uV / 1000;
 142         u64 pmV = pdata->pullup_uV / 1000;
 143         u64 N, puO, pdO;
 144         puO = pdata->pullup_ohm;
 145         pdO = pdata->pulldown_ohm;
 146
 147         if (mV == 0) {
 148                 if (pdata->connect == NTC_CONNECTED_POSITIVE)
 149                         return UINT_MAX;
 150                 return 0;
 151         }
 152         if (mV >= pmV)
 153                 return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
 154                         0 : UINT_MAX;
 155
 156         if (pdata->connect == NTC_CONNECTED_POSITIVE && puO == 0)
 157                 N = div64_u64_safe(pdO * (pmV - mV), mV);
 158         else if (pdata->connect == NTC_CONNECTED_GROUND && pdO == 0)
 159                 N = div64_u64_safe(puO * mV, pmV - mV);
 160         else if (pdata->connect == NTC_CONNECTED_POSITIVE)
 161                 N = div64_u64_safe(pdO * puO * (pmV - mV),
 162                                 puO * mV - pdO * (pmV - mV));
 163         else
 164                 N = div64_u64_safe(pdO * puO * mV, pdO * (pmV - mV) - puO * mV);
 165
 166         return (unsigned int) N;
 167 }
 168
 169 static int lookup_comp(struct ntc_data *data,
 170                 unsigned int ohm, int *i_low, int *i_high)
 171 {
 172         int start, end, mid = -1;
 173
 174         /* Do a binary search on compensation table */
 175         start = 0;
 176         end = data->n_comp;
 177
 178         while (end > start) {
 179                 mid = start + (end - start) / 2;
 180                 if (data->comp[mid].ohm < ohm)
 181                         end = mid;
 182                 else if (data->comp[mid].ohm > ohm)
 183                         start = mid + 1;
 184                 else
 185                         break;
 186         }
 187
 188         if (mid == 0) {
 189                 if (data->comp[mid].ohm > ohm) {
 190                         *i_high = mid;
 191                         *i_low = mid + 1;
 192                         return 0;
 193                 } else {
 194                         *i_low = mid;
 195                         *i_high = -1;
 196                         return -EINVAL;
 197                 }
 198         }
 199         if (mid == (data->n_comp - 1)) {
 200                 if (data->comp[mid].ohm <= ohm) {
 201                         *i_low = mid;
 202                         *i_high = mid - 1;
 203                         return 0;
 204                 } else {
 205                         *i_low = -1;
 206                         *i_high = mid;
 207                         return -EINVAL;
 208                 }
 209         }
 210
 211         if (data->comp[mid].ohm <= ohm) {
 212                 *i_low = mid;
 213                 *i_high = mid - 1;
 214         } else {
 215                 *i_low = mid + 1;
 216                 *i_high = mid;
 217         }
 218
 219         return 0;
 220 }
 221
 222 static int get_temp_mC(struct ntc_data *data, unsigned int ohm, int *temp)
 223 {
 224         int low, high;
 225         int ret;
 226
 227         ret = lookup_comp(data, ohm, &low, &high);
 228         if (ret) {
 229                 /* Unable to use linear approximation */
 230                 if (low != -1)
 231                         *temp = data->comp[low].temp_C * 1000;
 232                 else if (high != -1)
 233                         *temp = data->comp[high].temp_C * 1000;
 234                 else
 235                         return ret;
 236         } else {
 237                 *temp = data->comp[low].temp_C * 1000 +
 238                         ((data->comp[high].temp_C - data->comp[low].temp_C) *
 239                          1000 * ((int)ohm - (int)data->comp[low].ohm)) /
 240                         ((int)data->comp[high].ohm - (int)data->comp[low].ohm);
 241         }
 242
 243         return 0;
 244 }
 245
 246 static int ntc_thermistor_read(struct ntc_data *data, int *temp)
 247 {
 248         int ret;
 249         int read_ohm, read_uV;
 250         unsigned int ohm = 0;
 251
 252         if (data->pdata->read_ohm) {
 253                 read_ohm = data->pdata->read_ohm();
 254                 if (read_ohm < 0)
 255                         return read_ohm;
 256                 ohm = (unsigned int)read_ohm;
 257         }
 258
 259         if (data->pdata->read_uV) {
 260                 read_uV = data->pdata->read_uV();
 261                 if (read_uV < 0)
 262                         return read_uV;
 263                 ohm = get_ohm_of_thermistor(data, (unsigned int)read_uV);
 264         }
 265
 266         ret = get_temp_mC(data, ohm, temp);
 267         if (ret) {
 268                 dev_dbg(data->dev, "Sensor reading function not available.\n");
 269                 return ret;
 270         }
 271
 272         return 0;
 273 }
 274
 275 static ssize_t ntc_show_name(struct device *dev,
 276                 struct device_attribute *attr, char *buf)
 277 {
 278         struct ntc_data *data = dev_get_drvdata(dev);
 279
 280         return sprintf(buf, "%s\n", data->name);
 281 }
 282
 283 static ssize_t ntc_show_type(struct device *dev,
 284                 struct device_attribute *attr, char *buf)
 285 {
 286         return sprintf(buf, "4\n");
 287 }
 288
 289 static ssize_t ntc_show_temp(struct device *dev,
 290                 struct device_attribute *attr, char *buf)
 291 {
 292         struct ntc_data *data = dev_get_drvdata(dev);
 293         int temp, ret;
 294
 295         ret = ntc_thermistor_read(data, &temp);
 296         if (ret)
 297                 return ret;
 298         return sprintf(buf, "%d\n", temp);
 299 }
 300
 301 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0);
 302 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0);
 303 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL);
 304
 305 static struct attribute *ntc_attributes[] = {
 306         &dev_attr_name.attr,
 307         &sensor_dev_attr_temp1_type.dev_attr.attr,
 308         &sensor_dev_attr_temp1_input.dev_attr.attr,
 309         NULL,
 310 };
 311
 312 static const struct attribute_group ntc_attr_group = {
 313         .attrs = ntc_attributes,
 314 };
 315
 316 static int __devinit ntc_thermistor_probe(struct platform_device *pdev)
 317 {
 318         struct ntc_data *data;
 319         struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data;
 320         int ret = 0;
 321
 322         if (!pdata) {
 323                 dev_err(&pdev->dev, "No platform init data supplied.\n");
 324                 return -ENODEV;
 325         }
 326
 327         /* Either one of the two is required. */
 328         if (!pdata->read_uV && !pdata->read_ohm) {
 329                 dev_err(&pdev->dev, "Both read_uV and read_ohm missing."
 330                                 "Need either one of the two.\n");
 331                 return -EINVAL;
 332         }
 333
 334         if (pdata->read_uV && pdata->read_ohm) {
 335                 dev_warn(&pdev->dev, "Only one of read_uV and read_ohm "
 336                                 "is needed; ignoring read_uV.\n");
 337                 pdata->read_uV = NULL;
 338         }
 339
 340         if (pdata->read_uV && (pdata->pullup_uV == 0 ||
 341                                 (pdata->pullup_ohm == 0 && pdata->connect ==
 342                                  NTC_CONNECTED_GROUND) ||
 343                                 (pdata->pulldown_ohm == 0 && pdata->connect ==
 344                                  NTC_CONNECTED_POSITIVE) ||
 345                                 (pdata->connect != NTC_CONNECTED_POSITIVE &&
 346                                  pdata->connect != NTC_CONNECTED_GROUND))) {
 347                 dev_err(&pdev->dev, "Required data to use read_uV not "
 348                                 "supplied.\n");
 349                 return -EINVAL;
 350         }
 351
 352         data = kzalloc(sizeof(struct ntc_data), GFP_KERNEL);
 353         if (!data)
 354                 return -ENOMEM;
 355
 356         data->dev = &pdev->dev;
 357         data->pdata = pdata;
 358         strncpy(data->name, pdev->id_entry->name, PLATFORM_NAME_SIZE);
 359
 360         switch (pdev->id_entry->driver_data) {
 361         case TYPE_NCPXXWB473:
 362                 data->comp = ncpXXwb473;
 363                 data->n_comp = ARRAY_SIZE(ncpXXwb473);
 364                 break;
 365         case TYPE_NCPXXWL333:
 366                 data->comp = ncpXXwl333;
 367                 data->n_comp = ARRAY_SIZE(ncpXXwl333);
 368                 break;
 369         default:
 370                 dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n",
 371                                 pdev->id_entry->driver_data,
 372                                 pdev->id_entry->name);
 373                 ret = -EINVAL;
 374                 goto err;
 375         }
 376
 377         platform_set_drvdata(pdev, data);
 378
 379         ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group);
 380         if (ret) {
 381                 dev_err(data->dev, "unable to create sysfs files\n");
 382                 goto err;
 383         }
 384
 385         data->hwmon_dev = hwmon_device_register(data->dev);
 386         if (IS_ERR_OR_NULL(data->hwmon_dev)) {
 387                 dev_err(data->dev, "unable to register as hwmon device.\n");
 388                 ret = -EINVAL;
 389                 goto err_after_sysfs;
 390         }
 391
 392         dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n",
 393                         pdev->name, pdev->id, pdev->id_entry->name,
 394                         pdev->id_entry->driver_data);
 395         return 0;
 396 err_after_sysfs:
 397         sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 398 err:
 399         kfree(data);
 400         return ret;
 401 }
 402
 403 static int __devexit ntc_thermistor_remove(struct platform_device *pdev)
 404 {
 405         struct ntc_data *data = platform_get_drvdata(pdev);
 406
 407         hwmon_device_unregister(data->hwmon_dev);
 408         sysfs_remove_group(&data->dev->kobj, &ntc_attr_group);
 409         platform_set_drvdata(pdev, NULL);
 410
 411         kfree(data);
 412
 413         return 0;
 414 }
 415
 416 static const struct platform_device_id ntc_thermistor_id[] = {
 417         { "ncp15wb473", TYPE_NCPXXWB473 },
 418         { "ncp18wb473", TYPE_NCPXXWB473 },
 419         { "ncp21wb473", TYPE_NCPXXWB473 },
 420         { "ncp03wb473", TYPE_NCPXXWB473 },
 421         { "ncp15wl333", TYPE_NCPXXWL333 },
 422         { },
 423 };
 424
 425 static struct platform_driver ntc_thermistor_driver = {
 426         .driver = {
 427                 .name = "ntc-thermistor",
 428                 .owner = THIS_MODULE,
 429         },
 430         .probe = ntc_thermistor_probe,
 431         .remove = __devexit_p(ntc_thermistor_remove),
 432         .id_table = ntc_thermistor_id,
 433 };
 434
 435 module_platform_driver(ntc_thermistor_driver);
 436
 437 MODULE_DESCRIPTION("NTC Thermistor Driver");
 438 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
 439 MODULE_LICENSE("GPL");
 440 MODULE_ALIAS("platform:ntc-thermistor");