linux/drivers/hwmon/ntc_thermistor.c
<<
>>
Prefs
   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * ntc_thermistor.c - NTC Thermistors
   4 *
   5 *  Copyright (C) 2010 Samsung Electronics
   6 *  MyungJoo Ham <myungjoo.ham@samsung.com>
   7 */
   8
   9#include <linux/slab.h>
  10#include <linux/module.h>
  11#include <linux/math64.h>
  12#include <linux/mod_devicetable.h>
  13#include <linux/platform_device.h>
  14#include <linux/property.h>
  15#include <linux/err.h>
  16#include <linux/fixp-arith.h>
  17#include <linux/iio/consumer.h>
  18#include <linux/hwmon.h>
  19
  20enum ntc_thermistor_type {
  21        TYPE_B57330V2103,
  22        TYPE_B57891S0103,
  23        TYPE_NCPXXWB473,
  24        TYPE_NCPXXWF104,
  25        TYPE_NCPXXWL333,
  26        TYPE_NCPXXXH103,
  27};
  28
  29struct ntc_compensation {
  30        int             temp_c;
  31        unsigned int    ohm;
  32};
  33
  34/*
  35 * Used as index in a zero-terminated array, holes not allowed so
  36 * that NTC_LAST is the first empty array entry.
  37 */
  38enum {
  39        NTC_B57330V2103,
  40        NTC_B57891S0103,
  41        NTC_NCP03WB473,
  42        NTC_NCP03WF104,
  43        NTC_NCP15WB473,
  44        NTC_NCP15WL333,
  45        NTC_NCP15XH103,
  46        NTC_NCP18WB473,
  47        NTC_NCP21WB473,
  48        NTC_SSG1404001221,
  49        NTC_LAST,
  50};
  51
  52static const struct platform_device_id ntc_thermistor_id[] = {
  53        [NTC_B57330V2103]     = { "b57330v2103",     TYPE_B57330V2103 },
  54        [NTC_B57891S0103]     = { "b57891s0103",     TYPE_B57891S0103 },
  55        [NTC_NCP03WB473]      = { "ncp03wb473",      TYPE_NCPXXWB473 },
  56        [NTC_NCP03WF104]      = { "ncp03wf104",      TYPE_NCPXXWF104 },
  57        [NTC_NCP15WB473]      = { "ncp15wb473",      TYPE_NCPXXWB473 },
  58        [NTC_NCP15WL333]      = { "ncp15wl333",      TYPE_NCPXXWL333 },
  59        [NTC_NCP15XH103]      = { "ncp15xh103",      TYPE_NCPXXXH103 },
  60        [NTC_NCP18WB473]      = { "ncp18wb473",      TYPE_NCPXXWB473 },
  61        [NTC_NCP21WB473]      = { "ncp21wb473",      TYPE_NCPXXWB473 },
  62        [NTC_SSG1404001221]   = { "ssg1404_001221",  TYPE_NCPXXWB473 },
  63        [NTC_LAST]            = { },
  64};
  65
  66/*
  67 * A compensation table should be sorted by the values of .ohm
  68 * in descending order.
  69 * The following compensation tables are from the specification of Murata NTC
  70 * Thermistors Datasheet
  71 */
  72static const struct ntc_compensation ncpXXwb473[] = {
  73        { .temp_c       = -40, .ohm     = 1747920 },
  74        { .temp_c       = -35, .ohm     = 1245428 },
  75        { .temp_c       = -30, .ohm     = 898485 },
  76        { .temp_c       = -25, .ohm     = 655802 },
  77        { .temp_c       = -20, .ohm     = 483954 },
  78        { .temp_c       = -15, .ohm     = 360850 },
  79        { .temp_c       = -10, .ohm     = 271697 },
  80        { .temp_c       = -5, .ohm      = 206463 },
  81        { .temp_c       = 0, .ohm       = 158214 },
  82        { .temp_c       = 5, .ohm       = 122259 },
  83        { .temp_c       = 10, .ohm      = 95227 },
  84        { .temp_c       = 15, .ohm      = 74730 },
  85        { .temp_c       = 20, .ohm      = 59065 },
  86        { .temp_c       = 25, .ohm      = 47000 },
  87        { .temp_c       = 30, .ohm      = 37643 },
  88        { .temp_c       = 35, .ohm      = 30334 },
  89        { .temp_c       = 40, .ohm      = 24591 },
  90        { .temp_c       = 45, .ohm      = 20048 },
  91        { .temp_c       = 50, .ohm      = 16433 },
  92        { .temp_c       = 55, .ohm      = 13539 },
  93        { .temp_c       = 60, .ohm      = 11209 },
  94        { .temp_c       = 65, .ohm      = 9328 },
  95        { .temp_c       = 70, .ohm      = 7798 },
  96        { .temp_c       = 75, .ohm      = 6544 },
  97        { .temp_c       = 80, .ohm      = 5518 },
  98        { .temp_c       = 85, .ohm      = 4674 },
  99        { .temp_c       = 90, .ohm      = 3972 },
 100        { .temp_c       = 95, .ohm      = 3388 },
 101        { .temp_c       = 100, .ohm     = 2902 },
 102        { .temp_c       = 105, .ohm     = 2494 },
 103        { .temp_c       = 110, .ohm     = 2150 },
 104        { .temp_c       = 115, .ohm     = 1860 },
 105        { .temp_c       = 120, .ohm     = 1615 },
 106        { .temp_c       = 125, .ohm     = 1406 },
 107};
 108static const struct ntc_compensation ncpXXwl333[] = {
 109        { .temp_c       = -40, .ohm     = 1610154 },
 110        { .temp_c       = -35, .ohm     = 1130850 },
 111        { .temp_c       = -30, .ohm     = 802609 },
 112        { .temp_c       = -25, .ohm     = 575385 },
 113        { .temp_c       = -20, .ohm     = 416464 },
 114        { .temp_c       = -15, .ohm     = 304219 },
 115        { .temp_c       = -10, .ohm     = 224193 },
 116        { .temp_c       = -5, .ohm      = 166623 },
 117        { .temp_c       = 0, .ohm       = 124850 },
 118        { .temp_c       = 5, .ohm       = 94287 },
 119        { .temp_c       = 10, .ohm      = 71747 },
 120        { .temp_c       = 15, .ohm      = 54996 },
 121        { .temp_c       = 20, .ohm      = 42455 },
 122        { .temp_c       = 25, .ohm      = 33000 },
 123        { .temp_c       = 30, .ohm      = 25822 },
 124        { .temp_c       = 35, .ohm      = 20335 },
 125        { .temp_c       = 40, .ohm      = 16115 },
 126        { .temp_c       = 45, .ohm      = 12849 },
 127        { .temp_c       = 50, .ohm      = 10306 },
 128        { .temp_c       = 55, .ohm      = 8314 },
 129        { .temp_c       = 60, .ohm      = 6746 },
 130        { .temp_c       = 65, .ohm      = 5503 },
 131        { .temp_c       = 70, .ohm      = 4513 },
 132        { .temp_c       = 75, .ohm      = 3721 },
 133        { .temp_c       = 80, .ohm      = 3084 },
 134        { .temp_c       = 85, .ohm      = 2569 },
 135        { .temp_c       = 90, .ohm      = 2151 },
 136        { .temp_c       = 95, .ohm      = 1809 },
 137        { .temp_c       = 100, .ohm     = 1529 },
 138        { .temp_c       = 105, .ohm     = 1299 },
 139        { .temp_c       = 110, .ohm     = 1108 },
 140        { .temp_c       = 115, .ohm     = 949 },
 141        { .temp_c       = 120, .ohm     = 817 },
 142        { .temp_c       = 125, .ohm     = 707 },
 143};
 144
 145static const struct ntc_compensation ncpXXwf104[] = {
 146        { .temp_c       = -40, .ohm     = 4397119 },
 147        { .temp_c       = -35, .ohm     = 3088599 },
 148        { .temp_c       = -30, .ohm     = 2197225 },
 149        { .temp_c       = -25, .ohm     = 1581881 },
 150        { .temp_c       = -20, .ohm     = 1151037 },
 151        { .temp_c       = -15, .ohm     = 846579 },
 152        { .temp_c       = -10, .ohm     = 628988 },
 153        { .temp_c       = -5, .ohm      = 471632 },
 154        { .temp_c       = 0, .ohm       = 357012 },
 155        { .temp_c       = 5, .ohm       = 272500 },
 156        { .temp_c       = 10, .ohm      = 209710 },
 157        { .temp_c       = 15, .ohm      = 162651 },
 158        { .temp_c       = 20, .ohm      = 127080 },
 159        { .temp_c       = 25, .ohm      = 100000 },
 160        { .temp_c       = 30, .ohm      = 79222 },
 161        { .temp_c       = 35, .ohm      = 63167 },
 162        { .temp_c       = 40, .ohm      = 50677 },
 163        { .temp_c       = 45, .ohm      = 40904 },
 164        { .temp_c       = 50, .ohm      = 33195 },
 165        { .temp_c       = 55, .ohm      = 27091 },
 166        { .temp_c       = 60, .ohm      = 22224 },
 167        { .temp_c       = 65, .ohm      = 18323 },
 168        { .temp_c       = 70, .ohm      = 15184 },
 169        { .temp_c       = 75, .ohm      = 12635 },
 170        { .temp_c       = 80, .ohm      = 10566 },
 171        { .temp_c       = 85, .ohm      = 8873 },
 172        { .temp_c       = 90, .ohm      = 7481 },
 173        { .temp_c       = 95, .ohm      = 6337 },
 174        { .temp_c       = 100, .ohm     = 5384 },
 175        { .temp_c       = 105, .ohm     = 4594 },
 176        { .temp_c       = 110, .ohm     = 3934 },
 177        { .temp_c       = 115, .ohm     = 3380 },
 178        { .temp_c       = 120, .ohm     = 2916 },
 179        { .temp_c       = 125, .ohm     = 2522 },
 180};
 181
 182static const struct ntc_compensation ncpXXxh103[] = {
 183        { .temp_c       = -40, .ohm     = 247565 },
 184        { .temp_c       = -35, .ohm     = 181742 },
 185        { .temp_c       = -30, .ohm     = 135128 },
 186        { .temp_c       = -25, .ohm     = 101678 },
 187        { .temp_c       = -20, .ohm     = 77373 },
 188        { .temp_c       = -15, .ohm     = 59504 },
 189        { .temp_c       = -10, .ohm     = 46222 },
 190        { .temp_c       = -5, .ohm      = 36244 },
 191        { .temp_c       = 0, .ohm       = 28674 },
 192        { .temp_c       = 5, .ohm       = 22878 },
 193        { .temp_c       = 10, .ohm      = 18399 },
 194        { .temp_c       = 15, .ohm      = 14910 },
 195        { .temp_c       = 20, .ohm      = 12169 },
 196        { .temp_c       = 25, .ohm      = 10000 },
 197        { .temp_c       = 30, .ohm      = 8271 },
 198        { .temp_c       = 35, .ohm      = 6883 },
 199        { .temp_c       = 40, .ohm      = 5762 },
 200        { .temp_c       = 45, .ohm      = 4851 },
 201        { .temp_c       = 50, .ohm      = 4105 },
 202        { .temp_c       = 55, .ohm      = 3492 },
 203        { .temp_c       = 60, .ohm      = 2985 },
 204        { .temp_c       = 65, .ohm      = 2563 },
 205        { .temp_c       = 70, .ohm      = 2211 },
 206        { .temp_c       = 75, .ohm      = 1915 },
 207        { .temp_c       = 80, .ohm      = 1666 },
 208        { .temp_c       = 85, .ohm      = 1454 },
 209        { .temp_c       = 90, .ohm      = 1275 },
 210        { .temp_c       = 95, .ohm      = 1121 },
 211        { .temp_c       = 100, .ohm     = 990 },
 212        { .temp_c       = 105, .ohm     = 876 },
 213        { .temp_c       = 110, .ohm     = 779 },
 214        { .temp_c       = 115, .ohm     = 694 },
 215        { .temp_c       = 120, .ohm     = 620 },
 216        { .temp_c       = 125, .ohm     = 556 },
 217};
 218
 219/*
 220 * The following compensation tables are from the specifications in EPCOS NTC
 221 * Thermistors Datasheets
 222 */
 223static const struct ntc_compensation b57330v2103[] = {
 224        { .temp_c       = -40, .ohm     = 190030 },
 225        { .temp_c       = -35, .ohm     = 145360 },
 226        { .temp_c       = -30, .ohm     = 112060 },
 227        { .temp_c       = -25, .ohm     = 87041 },
 228        { .temp_c       = -20, .ohm     = 68104 },
 229        { .temp_c       = -15, .ohm     = 53665 },
 230        { .temp_c       = -10, .ohm     = 42576 },
 231        { .temp_c       = -5, .ohm      = 34001 },
 232        { .temp_c       = 0, .ohm       = 27326 },
 233        { .temp_c       = 5, .ohm       = 22096 },
 234        { .temp_c       = 10, .ohm      = 17973 },
 235        { .temp_c       = 15, .ohm      = 14703 },
 236        { .temp_c       = 20, .ohm      = 12090 },
 237        { .temp_c       = 25, .ohm      = 10000 },
 238        { .temp_c       = 30, .ohm      = 8311 },
 239        { .temp_c       = 35, .ohm      = 6941 },
 240        { .temp_c       = 40, .ohm      = 5825 },
 241        { .temp_c       = 45, .ohm      = 4911 },
 242        { .temp_c       = 50, .ohm      = 4158 },
 243        { .temp_c       = 55, .ohm      = 3536 },
 244        { .temp_c       = 60, .ohm      = 3019 },
 245        { .temp_c       = 65, .ohm      = 2588 },
 246        { .temp_c       = 70, .ohm      = 2227 },
 247        { .temp_c       = 75, .ohm      = 1924 },
 248        { .temp_c       = 80, .ohm      = 1668 },
 249        { .temp_c       = 85, .ohm      = 1451 },
 250        { .temp_c       = 90, .ohm      = 1266 },
 251        { .temp_c       = 95, .ohm      = 1108 },
 252        { .temp_c       = 100, .ohm     = 973 },
 253        { .temp_c       = 105, .ohm     = 857 },
 254        { .temp_c       = 110, .ohm     = 757 },
 255        { .temp_c       = 115, .ohm     = 671 },
 256        { .temp_c       = 120, .ohm     = 596 },
 257        { .temp_c       = 125, .ohm     = 531 },
 258};
 259
 260static const struct ntc_compensation b57891s0103[] = {
 261        { .temp_c       = -55.0, .ohm   = 878900 },
 262        { .temp_c       = -50.0, .ohm   = 617590 },
 263        { .temp_c       = -45.0, .ohm   = 439340 },
 264        { .temp_c       = -40.0, .ohm   = 316180 },
 265        { .temp_c       = -35.0, .ohm   = 230060 },
 266        { .temp_c       = -30.0, .ohm   = 169150 },
 267        { .temp_c       = -25.0, .ohm   = 125550 },
 268        { .temp_c       = -20.0, .ohm   = 94143 },
 269        { .temp_c       = -15.0, .ohm   = 71172 },
 270        { .temp_c       = -10.0, .ohm   = 54308 },
 271        { .temp_c       = -5.0, .ohm    = 41505 },
 272        { .temp_c       = 0.0, .ohm     = 32014 },
 273        { .temp_c       = 5.0, .ohm     = 25011 },
 274        { .temp_c       = 10.0, .ohm    = 19691 },
 275        { .temp_c       = 15.0, .ohm    = 15618 },
 276        { .temp_c       = 20.0, .ohm    = 12474 },
 277        { .temp_c       = 25.0, .ohm    = 10000 },
 278        { .temp_c       = 30.0, .ohm    = 8080 },
 279        { .temp_c       = 35.0, .ohm    = 6569 },
 280        { .temp_c       = 40.0, .ohm    = 5372 },
 281        { .temp_c       = 45.0, .ohm    = 4424 },
 282        { .temp_c       = 50.0, .ohm    = 3661 },
 283        { .temp_c       = 55.0, .ohm    = 3039 },
 284        { .temp_c       = 60.0, .ohm    = 2536 },
 285        { .temp_c       = 65.0, .ohm    = 2128 },
 286        { .temp_c       = 70.0, .ohm    = 1794 },
 287        { .temp_c       = 75.0, .ohm    = 1518 },
 288        { .temp_c       = 80.0, .ohm    = 1290 },
 289        { .temp_c       = 85.0, .ohm    = 1100 },
 290        { .temp_c       = 90.0, .ohm    = 942 },
 291        { .temp_c       = 95.0, .ohm    = 809 },
 292        { .temp_c       = 100.0, .ohm   = 697 },
 293        { .temp_c       = 105.0, .ohm   = 604 },
 294        { .temp_c       = 110.0, .ohm   = 525 },
 295        { .temp_c       = 115.0, .ohm   = 457 },
 296        { .temp_c       = 120.0, .ohm   = 400 },
 297        { .temp_c       = 125.0, .ohm   = 351 },
 298        { .temp_c       = 130.0, .ohm   = 308 },
 299        { .temp_c       = 135.0, .ohm   = 272 },
 300        { .temp_c       = 140.0, .ohm   = 240 },
 301        { .temp_c       = 145.0, .ohm   = 213 },
 302        { .temp_c       = 150.0, .ohm   = 189 },
 303        { .temp_c       = 155.0, .ohm   = 168 },
 304};
 305
 306struct ntc_type {
 307        const struct ntc_compensation *comp;
 308        int n_comp;
 309};
 310
 311#define NTC_TYPE(ntc, compensation) \
 312[(ntc)] = { .comp = (compensation), .n_comp = ARRAY_SIZE(compensation) }
 313
 314static const struct ntc_type ntc_type[] = {
 315        NTC_TYPE(TYPE_B57330V2103, b57330v2103),
 316        NTC_TYPE(TYPE_B57891S0103, b57891s0103),
 317        NTC_TYPE(TYPE_NCPXXWB473,  ncpXXwb473),
 318        NTC_TYPE(TYPE_NCPXXWF104,  ncpXXwf104),
 319        NTC_TYPE(TYPE_NCPXXWL333,  ncpXXwl333),
 320        NTC_TYPE(TYPE_NCPXXXH103,  ncpXXxh103),
 321};
 322
 323/*
 324 * pullup_uV, pullup_ohm, pulldown_ohm, and connect are required.
 325 *
 326 * How to setup pullup_ohm, pulldown_ohm, and connect is
 327 * described at Documentation/hwmon/ntc_thermistor.rst
 328 *
 329 * pullup/down_ohm: 0 for infinite / not-connected
 330 *
 331 * chan: iio_channel pointer to communicate with the ADC which the
 332 * thermistor is using for conversion of the analog values.
 333 */
 334struct ntc_data {
 335        const struct ntc_compensation *comp;
 336        int n_comp;
 337        unsigned int pullup_uv;
 338        unsigned int pullup_ohm;
 339        unsigned int pulldown_ohm;
 340        enum { NTC_CONNECTED_POSITIVE, NTC_CONNECTED_GROUND } connect;
 341        struct iio_channel *chan;
 342};
 343
 344static int ntc_adc_iio_read(struct ntc_data *data)
 345{
 346        struct iio_channel *channel = data->chan;
 347        int uv, ret;
 348
 349        ret = iio_read_channel_processed_scale(channel, &uv, 1000);
 350        if (ret < 0) {
 351                int raw;
 352
 353                /*
 354                 * This fallback uses a raw read and then
 355                 * assumes the ADC is 12 bits, scaling with
 356                 * a factor 1000 to get to microvolts.
 357                 */
 358                ret = iio_read_channel_raw(channel, &raw);
 359                if (ret < 0) {
 360                        pr_err("read channel() error: %d\n", ret);
 361                        return ret;
 362                }
 363                ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000);
 364                if (ret < 0) {
 365                        /* Assume 12 bit ADC with vref at pullup_uv */
 366                        uv = (data->pullup_uv * (s64)raw) >> 12;
 367                }
 368        }
 369
 370        return uv;
 371}
 372
 373static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
 374{
 375        if (divisor == 0 && dividend == 0)
 376                return 0;
 377        if (divisor == 0)
 378                return UINT_MAX;
 379        return div64_u64(dividend, divisor);
 380}
 381
 382static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv)
 383{
 384        u32 puv = data->pullup_uv;
 385        u64 n, puo, pdo;
 386        puo = data->pullup_ohm;
 387        pdo = data->pulldown_ohm;
 388
 389        if (uv == 0)
 390                return (data->connect == NTC_CONNECTED_POSITIVE) ?
 391                        INT_MAX : 0;
 392        if (uv >= puv)
 393                return (data->connect == NTC_CONNECTED_POSITIVE) ?
 394                        0 : INT_MAX;
 395
 396        if (data->connect == NTC_CONNECTED_POSITIVE && puo == 0)
 397                n = div_u64(pdo * (puv - uv), uv);
 398        else if (data->connect == NTC_CONNECTED_GROUND && pdo == 0)
 399                n = div_u64(puo * uv, puv - uv);
 400        else if (data->connect == NTC_CONNECTED_POSITIVE)
 401                n = div64_u64_safe(pdo * puo * (puv - uv),
 402                                puo * uv - pdo * (puv - uv));
 403        else
 404                n = div64_u64_safe(pdo * puo * uv, pdo * (puv - uv) - puo * uv);
 405
 406        if (n > INT_MAX)
 407                n = INT_MAX;
 408        return n;
 409}
 410
 411static void lookup_comp(struct ntc_data *data, unsigned int ohm,
 412                        int *i_low, int *i_high)
 413{
 414        int start, end, mid;
 415
 416        /*
 417         * Handle special cases: Resistance is higher than or equal to
 418         * resistance in first table entry, or resistance is lower or equal
 419         * to resistance in last table entry.
 420         * In these cases, return i_low == i_high, either pointing to the
 421         * beginning or to the end of the table depending on the condition.
 422         */
 423        if (ohm >= data->comp[0].ohm) {
 424                *i_low = 0;
 425                *i_high = 0;
 426                return;
 427        }
 428        if (ohm <= data->comp[data->n_comp - 1].ohm) {
 429                *i_low = data->n_comp - 1;
 430                *i_high = data->n_comp - 1;
 431                return;
 432        }
 433
 434        /* Do a binary search on compensation table */
 435        start = 0;
 436        end = data->n_comp;
 437        while (start < end) {
 438                mid = start + (end - start) / 2;
 439                /*
 440                 * start <= mid < end
 441                 * data->comp[start].ohm > ohm >= data->comp[end].ohm
 442                 *
 443                 * We could check for "ohm == data->comp[mid].ohm" here, but
 444                 * that is a quite unlikely condition, and we would have to
 445                 * check again after updating start. Check it at the end instead
 446                 * for simplicity.
 447                 */
 448                if (ohm >= data->comp[mid].ohm) {
 449                        end = mid;
 450                } else {
 451                        start = mid + 1;
 452                        /*
 453                         * ohm >= data->comp[start].ohm might be true here,
 454                         * since we set start to mid + 1. In that case, we are
 455                         * done. We could keep going, but the condition is quite
 456                         * likely to occur, so it is worth checking for it.
 457                         */
 458                        if (ohm >= data->comp[start].ohm)
 459                                end = start;
 460                }
 461                /*
 462                 * start <= end
 463                 * data->comp[start].ohm >= ohm >= data->comp[end].ohm
 464                 */
 465        }
 466        /*
 467         * start == end
 468         * ohm >= data->comp[end].ohm
 469         */
 470        *i_low = end;
 471        if (ohm == data->comp[end].ohm)
 472                *i_high = end;
 473        else
 474                *i_high = end - 1;
 475}
 476
 477static int get_temp_mc(struct ntc_data *data, unsigned int ohm)
 478{
 479        int low, high;
 480        int temp;
 481
 482        lookup_comp(data, ohm, &low, &high);
 483        /*
 484         * First multiplying the table temperatures with 1000 to get to
 485         * millicentigrades (which is what we want) and then interpolating
 486         * will give the best precision.
 487         */
 488        temp = fixp_linear_interpolate(data->comp[low].ohm,
 489                                       data->comp[low].temp_c * 1000,
 490                                       data->comp[high].ohm,
 491                                       data->comp[high].temp_c * 1000,
 492                                       ohm);
 493        return temp;
 494}
 495
 496static int ntc_thermistor_get_ohm(struct ntc_data *data)
 497{
 498        int read_uv;
 499
 500        read_uv = ntc_adc_iio_read(data);
 501        if (read_uv < 0)
 502                return read_uv;
 503        return get_ohm_of_thermistor(data, read_uv);
 504}
 505
 506static int ntc_read(struct device *dev, enum hwmon_sensor_types type,
 507                    u32 attr, int channel, long *val)
 508{
 509        struct ntc_data *data = dev_get_drvdata(dev);
 510        int ohm;
 511
 512        switch (type) {
 513        case hwmon_temp:
 514                switch (attr) {
 515                case hwmon_temp_input:
 516                        ohm = ntc_thermistor_get_ohm(data);
 517                        if (ohm < 0)
 518                                return ohm;
 519                        *val = get_temp_mc(data, ohm);
 520                        return 0;
 521                case hwmon_temp_type:
 522                        *val = 4;
 523                        return 0;
 524                default:
 525                        break;
 526                }
 527                break;
 528        default:
 529                break;
 530        }
 531        return -EINVAL;
 532}
 533
 534static umode_t ntc_is_visible(const void *data, enum hwmon_sensor_types type,
 535                              u32 attr, int channel)
 536{
 537        if (type == hwmon_temp) {
 538                switch (attr) {
 539                case hwmon_temp_input:
 540                case hwmon_temp_type:
 541                        return 0444;
 542                default:
 543                        break;
 544                }
 545        }
 546        return 0;
 547}
 548
 549static const struct hwmon_channel_info *ntc_info[] = {
 550        HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
 551        HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_TYPE),
 552        NULL
 553};
 554
 555static const struct hwmon_ops ntc_hwmon_ops = {
 556        .is_visible = ntc_is_visible,
 557        .read = ntc_read,
 558};
 559
 560static const struct hwmon_chip_info ntc_chip_info = {
 561        .ops = &ntc_hwmon_ops,
 562        .info = ntc_info,
 563};
 564
 565static int ntc_thermistor_parse_props(struct device *dev,
 566                                      struct ntc_data *data)
 567{
 568        struct iio_channel *chan;
 569        enum iio_chan_type type;
 570        int ret;
 571
 572        chan = devm_iio_channel_get(dev, NULL);
 573        if (IS_ERR(chan))
 574                return PTR_ERR(chan);
 575
 576        ret = iio_get_channel_type(chan, &type);
 577        if (ret < 0)
 578                return ret;
 579
 580        if (type != IIO_VOLTAGE)
 581                return -EINVAL;
 582
 583        ret = device_property_read_u32(dev, "pullup-uv", &data->pullup_uv);
 584        if (ret)
 585                return dev_err_probe(dev,  ret, "pullup-uv not specified\n");
 586
 587        ret = device_property_read_u32(dev, "pullup-ohm", &data->pullup_ohm);
 588        if (ret)
 589                return dev_err_probe(dev,  ret, "pullup-ohm not specified\n");
 590
 591        ret = device_property_read_u32(dev, "pulldown-ohm", &data->pulldown_ohm);
 592        if (ret)
 593                return dev_err_probe(dev,  ret, "pulldown-ohm not specified\n");
 594
 595        if (device_property_read_bool(dev, "connected-positive"))
 596                data->connect = NTC_CONNECTED_POSITIVE;
 597        else /* status change should be possible if not always on. */
 598                data->connect = NTC_CONNECTED_GROUND;
 599
 600        data->chan = chan;
 601
 602        return 0;
 603}
 604
 605static int ntc_thermistor_probe(struct platform_device *pdev)
 606{
 607        struct device *dev = &pdev->dev;
 608        const struct platform_device_id *pdev_id;
 609        struct device *hwmon_dev;
 610        struct ntc_data *data;
 611        int ret;
 612
 613        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 614        if (!data)
 615                return -ENOMEM;
 616
 617        ret = ntc_thermistor_parse_props(dev, data);
 618        if (ret)
 619                return ret;
 620
 621        if (data->pullup_uv == 0 ||
 622            (data->pullup_ohm == 0 && data->connect ==
 623             NTC_CONNECTED_GROUND) ||
 624            (data->pulldown_ohm == 0 && data->connect ==
 625             NTC_CONNECTED_POSITIVE) ||
 626            (data->connect != NTC_CONNECTED_POSITIVE &&
 627             data->connect != NTC_CONNECTED_GROUND)) {
 628                dev_err(dev, "Required data to use NTC driver not supplied.\n");
 629                return -EINVAL;
 630        }
 631
 632        pdev_id = device_get_match_data(dev);
 633
 634        if (pdev_id->driver_data >= ARRAY_SIZE(ntc_type)) {
 635                dev_err(dev, "Unknown device type: %lu(%s)\n",
 636                                pdev_id->driver_data, pdev_id->name);
 637                return -EINVAL;
 638        }
 639
 640        data->comp   = ntc_type[pdev_id->driver_data].comp;
 641        data->n_comp = ntc_type[pdev_id->driver_data].n_comp;
 642
 643        hwmon_dev = devm_hwmon_device_register_with_info(dev, pdev_id->name,
 644                                                         data, &ntc_chip_info,
 645                                                         NULL);
 646        if (IS_ERR(hwmon_dev)) {
 647                dev_err(dev, "unable to register as hwmon device.\n");
 648                return PTR_ERR(hwmon_dev);
 649        }
 650
 651        dev_info(dev, "Thermistor type: %s successfully probed.\n",
 652                 pdev_id->name);
 653
 654        return 0;
 655}
 656
 657static const struct of_device_id ntc_match[] = {
 658        { .compatible = "epcos,b57330v2103",
 659                .data = &ntc_thermistor_id[NTC_B57330V2103]},
 660        { .compatible = "epcos,b57891s0103",
 661                .data = &ntc_thermistor_id[NTC_B57891S0103] },
 662        { .compatible = "murata,ncp03wb473",
 663                .data = &ntc_thermistor_id[NTC_NCP03WB473] },
 664        { .compatible = "murata,ncp03wf104",
 665                .data = &ntc_thermistor_id[NTC_NCP03WF104] },
 666        { .compatible = "murata,ncp15wb473",
 667                .data = &ntc_thermistor_id[NTC_NCP15WB473] },
 668        { .compatible = "murata,ncp15wl333",
 669                .data = &ntc_thermistor_id[NTC_NCP15WL333] },
 670        { .compatible = "murata,ncp15xh103",
 671                .data = &ntc_thermistor_id[NTC_NCP15XH103] },
 672        { .compatible = "murata,ncp18wb473",
 673                .data = &ntc_thermistor_id[NTC_NCP18WB473] },
 674        { .compatible = "murata,ncp21wb473",
 675                .data = &ntc_thermistor_id[NTC_NCP21WB473] },
 676        { .compatible = "samsung,1404-001221",
 677                .data = &ntc_thermistor_id[NTC_SSG1404001221] },
 678
 679        /* Usage of vendor name "ntc" is deprecated */
 680        { .compatible = "ntc,ncp03wb473",
 681                .data = &ntc_thermistor_id[NTC_NCP03WB473] },
 682        { .compatible = "ntc,ncp15wb473",
 683                .data = &ntc_thermistor_id[NTC_NCP15WB473] },
 684        { .compatible = "ntc,ncp15wl333",
 685                .data = &ntc_thermistor_id[NTC_NCP15WL333] },
 686        { .compatible = "ntc,ncp18wb473",
 687                .data = &ntc_thermistor_id[NTC_NCP18WB473] },
 688        { .compatible = "ntc,ncp21wb473",
 689                .data = &ntc_thermistor_id[NTC_NCP21WB473] },
 690        { },
 691};
 692MODULE_DEVICE_TABLE(of, ntc_match);
 693
 694static struct platform_driver ntc_thermistor_driver = {
 695        .driver = {
 696                .name = "ntc-thermistor",
 697                .of_match_table = ntc_match,
 698        },
 699        .probe = ntc_thermistor_probe,
 700        .id_table = ntc_thermistor_id,
 701};
 702
 703module_platform_driver(ntc_thermistor_driver);
 704
 705MODULE_DESCRIPTION("NTC Thermistor Driver");
 706MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
 707MODULE_LICENSE("GPL");
 708MODULE_ALIAS("platform:ntc-thermistor");
 709