drivers/hwmon/ntc_thermistor.c

   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/pm_runtime.h>
  12 #include <linux/math64.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/err.h>
  15 #include <linux/of.h>
  16 #include <linux/of_device.h>
  17
  18 #include <linux/platform_data/ntc_thermistor.h>
  19
  20 #include <linux/iio/iio.h>
  21 #include <linux/iio/machine.h>
  22 #include <linux/iio/driver.h>
  23 #include <linux/iio/consumer.h>
  24
  25 #include <linux/hwmon.h>
  26
  27 struct ntc_compensation {
  28         int             temp_c;
  29         unsigned int    ohm;
  30 };
  31
  32 /*
  33  * Used as index in a zero-terminated array, holes not allowed so
  34  * that NTC_LAST is the first empty array entry.
  35  */
  36 enum {
  37         NTC_B57330V2103,
  38         NTC_B57891S0103,
  39         NTC_NCP03WB473,
  40         NTC_NCP03WF104,
  41         NTC_NCP15WB473,
  42         NTC_NCP15WL333,
  43         NTC_NCP15XH103,
  44         NTC_NCP18WB473,
  45         NTC_NCP21WB473,
  46         NTC_LAST,
  47 };
  48
  49 static const struct platform_device_id ntc_thermistor_id[] = {
  50         [NTC_B57330V2103]     = { "b57330v2103",     TYPE_B57330V2103 },
  51         [NTC_B57891S0103]     = { "b57891s0103",     TYPE_B57891S0103 },
  52         [NTC_NCP03WB473]      = { "ncp03wb473",      TYPE_NCPXXWB473 },
  53         [NTC_NCP03WF104]      = { "ncp03wf104",      TYPE_NCPXXWF104 },
  54         [NTC_NCP15WB473]      = { "ncp15wb473",      TYPE_NCPXXWB473 },
  55         [NTC_NCP15WL333]      = { "ncp15wl333",      TYPE_NCPXXWL333 },
  56         [NTC_NCP15XH103]      = { "ncp15xh103",      TYPE_NCPXXXH103 },
  57         [NTC_NCP18WB473]      = { "ncp18wb473",      TYPE_NCPXXWB473 },
  58         [NTC_NCP21WB473]      = { "ncp21wb473",      TYPE_NCPXXWB473 },
  59         [NTC_LAST]            = { },
  60 };
  61
  62 /*
  63  * A compensation table should be sorted by the values of .ohm
  64  * in descending order.
  65  * The following compensation tables are from the specification of Murata NTC
  66  * Thermistors Datasheet
  67  */
  68 static const struct ntc_compensation ncpXXwb473[] = {
  69         { .temp_c       = -40, .ohm     = 1747920 },
  70         { .temp_c       = -35, .ohm     = 1245428 },
  71         { .temp_c       = -30, .ohm     = 898485 },
  72         { .temp_c       = -25, .ohm     = 655802 },
  73         { .temp_c       = -20, .ohm     = 483954 },
  74         { .temp_c       = -15, .ohm     = 360850 },
  75         { .temp_c       = -10, .ohm     = 271697 },
  76         { .temp_c       = -5, .ohm      = 206463 },
  77         { .temp_c       = 0, .ohm       = 158214 },
  78         { .temp_c       = 5, .ohm       = 122259 },
  79         { .temp_c       = 10, .ohm      = 95227 },
  80         { .temp_c       = 15, .ohm      = 74730 },
  81         { .temp_c       = 20, .ohm      = 59065 },
  82         { .temp_c       = 25, .ohm      = 47000 },
  83         { .temp_c       = 30, .ohm      = 37643 },
  84         { .temp_c       = 35, .ohm      = 30334 },
  85         { .temp_c       = 40, .ohm      = 24591 },
  86         { .temp_c       = 45, .ohm      = 20048 },
  87         { .temp_c       = 50, .ohm      = 16433 },
  88         { .temp_c       = 55, .ohm      = 13539 },
  89         { .temp_c       = 60, .ohm      = 11209 },
  90         { .temp_c       = 65, .ohm      = 9328 },
  91         { .temp_c       = 70, .ohm      = 7798 },
  92         { .temp_c       = 75, .ohm      = 6544 },
  93         { .temp_c       = 80, .ohm      = 5518 },
  94         { .temp_c       = 85, .ohm      = 4674 },
  95         { .temp_c       = 90, .ohm      = 3972 },
  96         { .temp_c       = 95, .ohm      = 3388 },
  97         { .temp_c       = 100, .ohm     = 2902 },
  98         { .temp_c       = 105, .ohm     = 2494 },
  99         { .temp_c       = 110, .ohm     = 2150 },
 100         { .temp_c       = 115, .ohm     = 1860 },
 101         { .temp_c       = 120, .ohm     = 1615 },
 102         { .temp_c       = 125, .ohm     = 1406 },
 103 };
 104 static const struct ntc_compensation ncpXXwl333[] = {
 105         { .temp_c       = -40, .ohm     = 1610154 },
 106         { .temp_c       = -35, .ohm     = 1130850 },
 107         { .temp_c       = -30, .ohm     = 802609 },
 108         { .temp_c       = -25, .ohm     = 575385 },
 109         { .temp_c       = -20, .ohm     = 416464 },
 110         { .temp_c       = -15, .ohm     = 304219 },
 111         { .temp_c       = -10, .ohm     = 224193 },
 112         { .temp_c       = -5, .ohm      = 166623 },
 113         { .temp_c       = 0, .ohm       = 124850 },
 114         { .temp_c       = 5, .ohm       = 94287 },
 115         { .temp_c       = 10, .ohm      = 71747 },
 116         { .temp_c       = 15, .ohm      = 54996 },
 117         { .temp_c       = 20, .ohm      = 42455 },
 118         { .temp_c       = 25, .ohm      = 33000 },
 119         { .temp_c       = 30, .ohm      = 25822 },
 120         { .temp_c       = 35, .ohm      = 20335 },
 121         { .temp_c       = 40, .ohm      = 16115 },
 122         { .temp_c       = 45, .ohm      = 12849 },
 123         { .temp_c       = 50, .ohm      = 10306 },
 124         { .temp_c       = 55, .ohm      = 8314 },
 125         { .temp_c       = 60, .ohm      = 6746 },
 126         { .temp_c       = 65, .ohm      = 5503 },
 127         { .temp_c       = 70, .ohm      = 4513 },
 128         { .temp_c       = 75, .ohm      = 3721 },
 129         { .temp_c       = 80, .ohm      = 3084 },
 130         { .temp_c       = 85, .ohm      = 2569 },
 131         { .temp_c       = 90, .ohm      = 2151 },
 132         { .temp_c       = 95, .ohm      = 1809 },
 133         { .temp_c       = 100, .ohm     = 1529 },
 134         { .temp_c       = 105, .ohm     = 1299 },
 135         { .temp_c       = 110, .ohm     = 1108 },
 136         { .temp_c       = 115, .ohm     = 949 },
 137         { .temp_c       = 120, .ohm     = 817 },
 138         { .temp_c       = 125, .ohm     = 707 },
 139 };
 140
 141 static const struct ntc_compensation ncpXXwf104[] = {
 142         { .temp_c       = -40, .ohm     = 4397119 },
 143         { .temp_c       = -35, .ohm     = 3088599 },
 144         { .temp_c       = -30, .ohm     = 2197225 },
 145         { .temp_c       = -25, .ohm     = 1581881 },
 146         { .temp_c       = -20, .ohm     = 1151037 },
 147         { .temp_c       = -15, .ohm     = 846579 },
 148         { .temp_c       = -10, .ohm     = 628988 },
 149         { .temp_c       = -5, .ohm      = 471632 },
 150         { .temp_c       = 0, .ohm       = 357012 },
 151         { .temp_c       = 5, .ohm       = 272500 },
 152         { .temp_c       = 10, .ohm      = 209710 },
 153         { .temp_c       = 15, .ohm      = 162651 },
 154         { .temp_c       = 20, .ohm      = 127080 },
 155         { .temp_c       = 25, .ohm      = 100000 },
 156         { .temp_c       = 30, .ohm      = 79222 },
 157         { .temp_c       = 35, .ohm      = 63167 },
 158         { .temp_c       = 40, .ohm      = 50677 },
 159         { .temp_c       = 45, .ohm      = 40904 },
 160         { .temp_c       = 50, .ohm      = 33195 },
 161         { .temp_c       = 55, .ohm      = 27091 },
 162         { .temp_c       = 60, .ohm      = 22224 },
 163         { .temp_c       = 65, .ohm      = 18323 },
 164         { .temp_c       = 70, .ohm      = 15184 },
 165         { .temp_c       = 75, .ohm      = 12635 },
 166         { .temp_c       = 80, .ohm      = 10566 },
 167         { .temp_c       = 85, .ohm      = 8873 },
 168         { .temp_c       = 90, .ohm      = 7481 },
 169         { .temp_c       = 95, .ohm      = 6337 },
 170         { .temp_c       = 100, .ohm     = 5384 },
 171         { .temp_c       = 105, .ohm     = 4594 },
 172         { .temp_c       = 110, .ohm     = 3934 },
 173         { .temp_c       = 115, .ohm     = 3380 },
 174         { .temp_c       = 120, .ohm     = 2916 },
 175         { .temp_c       = 125, .ohm     = 2522 },
 176 };
 177
 178 static const struct ntc_compensation ncpXXxh103[] = {
 179         { .temp_c       = -40, .ohm     = 247565 },
 180         { .temp_c       = -35, .ohm     = 181742 },
 181         { .temp_c       = -30, .ohm     = 135128 },
 182         { .temp_c       = -25, .ohm     = 101678 },
 183         { .temp_c       = -20, .ohm     = 77373 },
 184         { .temp_c       = -15, .ohm     = 59504 },
 185         { .temp_c       = -10, .ohm     = 46222 },
 186         { .temp_c       = -5, .ohm      = 36244 },
 187         { .temp_c       = 0, .ohm       = 28674 },
 188         { .temp_c       = 5, .ohm       = 22878 },
 189         { .temp_c       = 10, .ohm      = 18399 },
 190         { .temp_c       = 15, .ohm      = 14910 },
 191         { .temp_c       = 20, .ohm      = 12169 },
 192         { .temp_c       = 25, .ohm      = 10000 },
 193         { .temp_c       = 30, .ohm      = 8271 },
 194         { .temp_c       = 35, .ohm      = 6883 },
 195         { .temp_c       = 40, .ohm      = 5762 },
 196         { .temp_c       = 45, .ohm      = 4851 },
 197         { .temp_c       = 50, .ohm      = 4105 },
 198         { .temp_c       = 55, .ohm      = 3492 },
 199         { .temp_c       = 60, .ohm      = 2985 },
 200         { .temp_c       = 65, .ohm      = 2563 },
 201         { .temp_c       = 70, .ohm      = 2211 },
 202         { .temp_c       = 75, .ohm      = 1915 },
 203         { .temp_c       = 80, .ohm      = 1666 },
 204         { .temp_c       = 85, .ohm      = 1454 },
 205         { .temp_c       = 90, .ohm      = 1275 },
 206         { .temp_c       = 95, .ohm      = 1121 },
 207         { .temp_c       = 100, .ohm     = 990 },
 208         { .temp_c       = 105, .ohm     = 876 },
 209         { .temp_c       = 110, .ohm     = 779 },
 210         { .temp_c       = 115, .ohm     = 694 },
 211         { .temp_c       = 120, .ohm     = 620 },
 212         { .temp_c       = 125, .ohm     = 556 },
 213 };
 214
 215 /*
 216  * The following compensation tables are from the specifications in EPCOS NTC
 217  * Thermistors Datasheets
 218  */
 219 static const struct ntc_compensation b57330v2103[] = {
 220         { .temp_c       = -40, .ohm     = 190030 },
 221         { .temp_c       = -35, .ohm     = 145360 },
 222         { .temp_c       = -30, .ohm     = 112060 },
 223         { .temp_c       = -25, .ohm     = 87041 },
 224         { .temp_c       = -20, .ohm     = 68104 },
 225         { .temp_c       = -15, .ohm     = 53665 },
 226         { .temp_c       = -10, .ohm     = 42576 },
 227         { .temp_c       = -5, .ohm      = 34001 },
 228         { .temp_c       = 0, .ohm       = 27326 },
 229         { .temp_c       = 5, .ohm       = 22096 },
 230         { .temp_c       = 10, .ohm      = 17973 },
 231         { .temp_c       = 15, .ohm      = 14703 },
 232         { .temp_c       = 20, .ohm      = 12090 },
 233         { .temp_c       = 25, .ohm      = 10000 },
 234         { .temp_c       = 30, .ohm      = 8311 },
 235         { .temp_c       = 35, .ohm      = 6941 },
 236         { .temp_c       = 40, .ohm      = 5825 },
 237         { .temp_c       = 45, .ohm      = 4911 },
 238         { .temp_c       = 50, .ohm      = 4158 },
 239         { .temp_c       = 55, .ohm      = 3536 },
 240         { .temp_c       = 60, .ohm      = 3019 },
 241         { .temp_c       = 65, .ohm      = 2588 },
 242         { .temp_c       = 70, .ohm      = 2227 },
 243         { .temp_c       = 75, .ohm      = 1924 },
 244         { .temp_c       = 80, .ohm      = 1668 },
 245         { .temp_c       = 85, .ohm      = 1451 },
 246         { .temp_c       = 90, .ohm      = 1266 },
 247         { .temp_c       = 95, .ohm      = 1108 },
 248         { .temp_c       = 100, .ohm     = 973 },
 249         { .temp_c       = 105, .ohm     = 857 },
 250         { .temp_c       = 110, .ohm     = 757 },
 251         { .temp_c       = 115, .ohm     = 671 },
 252         { .temp_c       = 120, .ohm     = 596 },
 253         { .temp_c       = 125, .ohm     = 531 },
 254 };
 255
 256 static const struct ntc_compensation b57891s0103[] = {
 257         { .temp_c       = -55.0, .ohm   = 878900 },
 258         { .temp_c       = -50.0, .ohm   = 617590 },
 259         { .temp_c       = -45.0, .ohm   = 439340 },
 260         { .temp_c       = -40.0, .ohm   = 316180 },
 261         { .temp_c       = -35.0, .ohm   = 230060 },
 262         { .temp_c       = -30.0, .ohm   = 169150 },
 263         { .temp_c       = -25.0, .ohm   = 125550 },
 264         { .temp_c       = -20.0, .ohm   = 94143 },
 265         { .temp_c       = -15.0, .ohm   = 71172 },
 266         { .temp_c       = -10.0, .ohm   = 54308 },
 267         { .temp_c       = -5.0, .ohm    = 41505 },
 268         { .temp_c       = 0.0, .ohm     = 32014 },
 269         { .temp_c       = 5.0, .ohm     = 25011 },
 270         { .temp_c       = 10.0, .ohm    = 19691 },
 271         { .temp_c       = 15.0, .ohm    = 15618 },
 272         { .temp_c       = 20.0, .ohm    = 12474 },
 273         { .temp_c       = 25.0, .ohm    = 10000 },
 274         { .temp_c       = 30.0, .ohm    = 8080 },
 275         { .temp_c       = 35.0, .ohm    = 6569 },
 276         { .temp_c       = 40.0, .ohm    = 5372 },
 277         { .temp_c       = 45.0, .ohm    = 4424 },
 278         { .temp_c       = 50.0, .ohm    = 3661 },
 279         { .temp_c       = 55.0, .ohm    = 3039 },
 280         { .temp_c       = 60.0, .ohm    = 2536 },
 281         { .temp_c       = 65.0, .ohm    = 2128 },
 282         { .temp_c       = 70.0, .ohm    = 1794 },
 283         { .temp_c       = 75.0, .ohm    = 1518 },
 284         { .temp_c       = 80.0, .ohm    = 1290 },
 285         { .temp_c       = 85.0, .ohm    = 1100 },
 286         { .temp_c       = 90.0, .ohm    = 942 },
 287         { .temp_c       = 95.0, .ohm    = 809 },
 288         { .temp_c       = 100.0, .ohm   = 697 },
 289         { .temp_c       = 105.0, .ohm   = 604 },
 290         { .temp_c       = 110.0, .ohm   = 525 },
 291         { .temp_c       = 115.0, .ohm   = 457 },
 292         { .temp_c       = 120.0, .ohm   = 400 },
 293         { .temp_c       = 125.0, .ohm   = 351 },
 294         { .temp_c       = 130.0, .ohm   = 308 },
 295         { .temp_c       = 135.0, .ohm   = 272 },
 296         { .temp_c       = 140.0, .ohm   = 240 },
 297         { .temp_c       = 145.0, .ohm   = 213 },
 298         { .temp_c       = 150.0, .ohm   = 189 },
 299         { .temp_c       = 155.0, .ohm   = 168 },
 300 };
 301
 302 struct ntc_type {
 303         const struct ntc_compensation *comp;
 304         int n_comp;
 305 };
 306
 307 #define NTC_TYPE(ntc, compensation) \
 308 [(ntc)] = { .comp = (compensation), .n_comp = ARRAY_SIZE(compensation) }
 309
 310 static const struct ntc_type ntc_type[] = {
 311         NTC_TYPE(TYPE_B57330V2103, b57330v2103),
 312         NTC_TYPE(TYPE_B57891S0103, b57891s0103),
 313         NTC_TYPE(TYPE_NCPXXWB473,  ncpXXwb473),
 314         NTC_TYPE(TYPE_NCPXXWF104,  ncpXXwf104),
 315         NTC_TYPE(TYPE_NCPXXWL333,  ncpXXwl333),
 316         NTC_TYPE(TYPE_NCPXXXH103,  ncpXXxh103),
 317 };
 318
 319 struct ntc_data {
 320         struct ntc_thermistor_platform_data *pdata;
 321         const struct ntc_compensation *comp;
 322         int n_comp;
 323 };
 324
 325 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO)
 326 static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
 327 {
 328         struct iio_channel *channel = pdata->chan;
 329         int raw, uv, ret;
 330
 331         ret = iio_read_channel_raw(channel, &raw);
 332         if (ret < 0) {
 333                 pr_err("read channel() error: %d\n", ret);
 334                 return ret;
 335         }
 336
 337         ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000);
 338         if (ret < 0) {
 339                 /* Assume 12 bit ADC with vref at pullup_uv */
 340                 uv = (pdata->pullup_uv * (s64)raw) >> 12;
 341         }
 342
 343         return uv;
 344 }
 345
 346 static const struct of_device_id ntc_match[] = {
 347         { .compatible = "epcos,b57330v2103",
 348                 .data = &ntc_thermistor_id[NTC_B57330V2103]},
 349         { .compatible = "epcos,b57891s0103",
 350                 .data = &ntc_thermistor_id[NTC_B57891S0103] },
 351         { .compatible = "murata,ncp03wb473",
 352                 .data = &ntc_thermistor_id[NTC_NCP03WB473] },
 353         { .compatible = "murata,ncp03wf104",
 354                 .data = &ntc_thermistor_id[NTC_NCP03WF104] },
 355         { .compatible = "murata,ncp15wb473",
 356                 .data = &ntc_thermistor_id[NTC_NCP15WB473] },
 357         { .compatible = "murata,ncp15wl333",
 358                 .data = &ntc_thermistor_id[NTC_NCP15WL333] },
 359         { .compatible = "murata,ncp15xh103",
 360                 .data = &ntc_thermistor_id[NTC_NCP15XH103] },
 361         { .compatible = "murata,ncp18wb473",
 362                 .data = &ntc_thermistor_id[NTC_NCP18WB473] },
 363         { .compatible = "murata,ncp21wb473",
 364                 .data = &ntc_thermistor_id[NTC_NCP21WB473] },
 365
 366         /* Usage of vendor name "ntc" is deprecated */
 367         { .compatible = "ntc,ncp03wb473",
 368                 .data = &ntc_thermistor_id[NTC_NCP03WB473] },
 369         { .compatible = "ntc,ncp15wb473",
 370                 .data = &ntc_thermistor_id[NTC_NCP15WB473] },
 371         { .compatible = "ntc,ncp15wl333",
 372                 .data = &ntc_thermistor_id[NTC_NCP15WL333] },
 373         { .compatible = "ntc,ncp18wb473",
 374                 .data = &ntc_thermistor_id[NTC_NCP18WB473] },
 375         { .compatible = "ntc,ncp21wb473",
 376                 .data = &ntc_thermistor_id[NTC_NCP21WB473] },
 377         { },
 378 };
 379 MODULE_DEVICE_TABLE(of, ntc_match);
 380
 381 static struct ntc_thermistor_platform_data *
 382 ntc_thermistor_parse_dt(struct device *dev)
 383 {
 384         struct iio_channel *chan;
 385         enum iio_chan_type type;
 386         struct device_node *np = dev->of_node;
 387         struct ntc_thermistor_platform_data *pdata;
 388         int ret;
 389
 390         if (!np)
 391                 return NULL;
 392
 393         pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
 394         if (!pdata)
 395                 return ERR_PTR(-ENOMEM);
 396
 397         chan = devm_iio_channel_get(dev, NULL);
 398         if (IS_ERR(chan))
 399                 return ERR_CAST(chan);
 400
 401         ret = iio_get_channel_type(chan, &type);
 402         if (ret < 0)
 403                 return ERR_PTR(ret);
 404
 405         if (type != IIO_VOLTAGE)
 406                 return ERR_PTR(-EINVAL);
 407
 408         if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv))
 409                 return ERR_PTR(-ENODEV);
 410         if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm))
 411                 return ERR_PTR(-ENODEV);
 412         if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm))
 413                 return ERR_PTR(-ENODEV);
 414
 415         if (of_find_property(np, "connected-positive", NULL))
 416                 pdata->connect = NTC_CONNECTED_POSITIVE;
 417         else /* status change should be possible if not always on. */
 418                 pdata->connect = NTC_CONNECTED_GROUND;
 419
 420         pdata->chan = chan;
 421         pdata->read_uv = ntc_adc_iio_read;
 422
 423         return pdata;
 424 }
 425 #else
 426 static struct ntc_thermistor_platform_data *
 427 ntc_thermistor_parse_dt(struct device *dev)
 428 {
 429         return NULL;
 430 }
 431
 432 #define ntc_match       NULL
 433
 434 #endif
 435
 436 static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
 437 {
 438         if (divisor == 0 && dividend == 0)
 439                 return 0;
 440         if (divisor == 0)
 441                 return UINT_MAX;
 442         return div64_u64(dividend, divisor);
 443 }
 444
 445 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv)
 446 {
 447         struct ntc_thermistor_platform_data *pdata = data->pdata;
 448         u32 puv = pdata->pullup_uv;
 449         u64 n, puo, pdo;
 450         puo = pdata->pullup_ohm;
 451         pdo = pdata->pulldown_ohm;
 452
 453         if (uv == 0)
 454                 return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
 455                         INT_MAX : 0;
 456         if (uv >= puv)
 457                 return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
 458                         0 : INT_MAX;
 459
 460         if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0)
 461                 n = div_u64(pdo * (puv - uv), uv);
 462         else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0)
 463                 n = div_u64(puo * uv, puv - uv);
 464         else if (pdata->connect == NTC_CONNECTED_POSITIVE)
 465                 n = div64_u64_safe(pdo * puo * (puv - uv),
 466                                 puo * uv - pdo * (puv - uv));
 467         else
 468                 n = div64_u64_safe(pdo * puo * uv, pdo * (puv - uv) - puo * uv);
 469
 470         if (n > INT_MAX)
 471                 n = INT_MAX;
 472         return n;
 473 }
 474
 475 static void lookup_comp(struct ntc_data *data, unsigned int ohm,
 476                         int *i_low, int *i_high)
 477 {
 478         int start, end, mid;
 479
 480         /*
 481          * Handle special cases: Resistance is higher than or equal to
 482          * resistance in first table entry, or resistance is lower or equal
 483          * to resistance in last table entry.
 484          * In these cases, return i_low == i_high, either pointing to the
 485          * beginning or to the end of the table depending on the condition.
 486          */
 487         if (ohm >= data->comp[0].ohm) {
 488                 *i_low = 0;
 489                 *i_high = 0;
 490                 return;
 491         }
 492         if (ohm <= data->comp[data->n_comp - 1].ohm) {
 493                 *i_low = data->n_comp - 1;
 494                 *i_high = data->n_comp - 1;
 495                 return;
 496         }
 497
 498         /* Do a binary search on compensation table */
 499         start = 0;
 500         end = data->n_comp;
 501         while (start < end) {
 502                 mid = start + (end - start) / 2;
 503                 /*
 504                  * start <= mid < end
 505                  * data->comp[start].ohm > ohm >= data->comp[end].ohm
 506                  *
 507                  * We could check for "ohm == data->comp[mid].ohm" here, but
 508                  * that is a quite unlikely condition, and we would have to
 509                  * check again after updating start. Check it at the end instead
 510                  * for simplicity.
 511                  */
 512                 if (ohm >= data->comp[mid].ohm) {
 513                         end = mid;
 514                 } else {
 515                         start = mid + 1;
 516                         /*
 517                          * ohm >= data->comp[start].ohm might be true here,
 518                          * since we set start to mid + 1. In that case, we are
 519                          * done. We could keep going, but the condition is quite
 520                          * likely to occur, so it is worth checking for it.
 521                          */
 522                         if (ohm >= data->comp[start].ohm)
 523                                 end = start;
 524                 }
 525                 /*
 526                  * start <= end
 527                  * data->comp[start].ohm >= ohm >= data->comp[end].ohm
 528                  */
 529         }
 530         /*
 531          * start == end
 532          * ohm >= data->comp[end].ohm
 533          */
 534         *i_low = end;
 535         if (ohm == data->comp[end].ohm)
 536                 *i_high = end;
 537         else
 538                 *i_high = end - 1;
 539 }
 540
 541 static int get_temp_mc(struct ntc_data *data, unsigned int ohm)
 542 {
 543         int low, high;
 544         int temp;
 545
 546         lookup_comp(data, ohm, &low, &high);
 547         if (low == high) {
 548                 /* Unable to use linear approximation */
 549                 temp = data->comp[low].temp_c * 1000;
 550         } else {
 551                 temp = data->comp[low].temp_c * 1000 +
 552                         ((data->comp[high].temp_c - data->comp[low].temp_c) *
 553                          1000 * ((int)ohm - (int)data->comp[low].ohm)) /
 554                         ((int)data->comp[high].ohm - (int)data->comp[low].ohm);
 555         }
 556         return temp;
 557 }
 558
 559 static int ntc_thermistor_get_ohm(struct ntc_data *data)
 560 {
 561         int read_uv;
 562
 563         if (data->pdata->read_ohm)
 564                 return data->pdata->read_ohm();
 565
 566         if (data->pdata->read_uv) {
 567                 read_uv = data->pdata->read_uv(data->pdata);
 568                 if (read_uv < 0)
 569                         return read_uv;
 570                 return get_ohm_of_thermistor(data, read_uv);
 571         }
 572         return -EINVAL;
 573 }
 574
 575 static int ntc_read(struct device *dev, enum hwmon_sensor_types type,
 576                     u32 attr, int channel, long *val)
 577 {
 578         struct ntc_data *data = dev_get_drvdata(dev);
 579         int ohm;
 580
 581         switch (type) {
 582         case hwmon_temp:
 583                 switch (attr) {
 584                 case hwmon_temp_input:
 585                         ohm = ntc_thermistor_get_ohm(data);
 586                         if (ohm < 0)
 587                                 return ohm;
 588                         *val = get_temp_mc(data, ohm);
 589                         return 0;
 590                 case hwmon_temp_type:
 591                         *val = 4;
 592                         return 0;
 593                 default:
 594                         break;
 595                 }
 596                 break;
 597         default:
 598                 break;
 599         }
 600         return -EINVAL;
 601 }
 602
 603 static umode_t ntc_is_visible(const void *data, enum hwmon_sensor_types type,
 604                               u32 attr, int channel)
 605 {
 606         if (type == hwmon_temp) {
 607                 switch (attr) {
 608                 case hwmon_temp_input:
 609                 case hwmon_temp_type:
 610                         return 0444;
 611                 default:
 612                         break;
 613                 }
 614         }
 615         return 0;
 616 }
 617
 618 static const struct hwmon_channel_info *ntc_info[] = {
 619         HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
 620         HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_TYPE),
 621         NULL
 622 };
 623
 624 static const struct hwmon_ops ntc_hwmon_ops = {
 625         .is_visible = ntc_is_visible,
 626         .read = ntc_read,
 627 };
 628
 629 static const struct hwmon_chip_info ntc_chip_info = {
 630         .ops = &ntc_hwmon_ops,
 631         .info = ntc_info,
 632 };
 633
 634 static int ntc_thermistor_probe(struct platform_device *pdev)
 635 {
 636         struct device *dev = &pdev->dev;
 637         const struct of_device_id *of_id =
 638                         of_match_device(of_match_ptr(ntc_match), dev);
 639         const struct platform_device_id *pdev_id;
 640         struct ntc_thermistor_platform_data *pdata;
 641         struct device *hwmon_dev;
 642         struct ntc_data *data;
 643
 644         pdata = ntc_thermistor_parse_dt(dev);
 645         if (IS_ERR(pdata))
 646                 return PTR_ERR(pdata);
 647         else if (pdata == NULL)
 648                 pdata = dev_get_platdata(dev);
 649
 650         if (!pdata) {
 651                 dev_err(dev, "No platform init data supplied.\n");
 652                 return -ENODEV;
 653         }
 654
 655         /* Either one of the two is required. */
 656         if (!pdata->read_uv && !pdata->read_ohm) {
 657                 dev_err(dev,
 658                         "Both read_uv and read_ohm missing. Need either one of the two.\n");
 659                 return -EINVAL;
 660         }
 661
 662         if (pdata->read_uv && pdata->read_ohm) {
 663                 dev_warn(dev,
 664                          "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n");
 665                 pdata->read_uv = NULL;
 666         }
 667
 668         if (pdata->read_uv && (pdata->pullup_uv == 0 ||
 669                                 (pdata->pullup_ohm == 0 && pdata->connect ==
 670                                  NTC_CONNECTED_GROUND) ||
 671                                 (pdata->pulldown_ohm == 0 && pdata->connect ==
 672                                  NTC_CONNECTED_POSITIVE) ||
 673                                 (pdata->connect != NTC_CONNECTED_POSITIVE &&
 674                                  pdata->connect != NTC_CONNECTED_GROUND))) {
 675                 dev_err(dev, "Required data to use read_uv not supplied.\n");
 676                 return -EINVAL;
 677         }
 678
 679         data = devm_kzalloc(dev, sizeof(struct ntc_data), GFP_KERNEL);
 680         if (!data)
 681                 return -ENOMEM;
 682
 683         pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);
 684
 685         data->pdata = pdata;
 686
 687         if (pdev_id->driver_data >= ARRAY_SIZE(ntc_type)) {
 688                 dev_err(dev, "Unknown device type: %lu(%s)\n",
 689                                 pdev_id->driver_data, pdev_id->name);
 690                 return -EINVAL;
 691         }
 692
 693         data->comp   = ntc_type[pdev_id->driver_data].comp;
 694         data->n_comp = ntc_type[pdev_id->driver_data].n_comp;
 695
 696         hwmon_dev = devm_hwmon_device_register_with_info(dev, pdev_id->name,
 697                                                          data, &ntc_chip_info,
 698                                                          NULL);
 699         if (IS_ERR(hwmon_dev)) {
 700                 dev_err(dev, "unable to register as hwmon device.\n");
 701                 return PTR_ERR(hwmon_dev);
 702         }
 703
 704         dev_info(dev, "Thermistor type: %s successfully probed.\n",
 705                  pdev_id->name);
 706
 707         return 0;
 708 }
 709
 710 static struct platform_driver ntc_thermistor_driver = {
 711         .driver = {
 712                 .name = "ntc-thermistor",
 713                 .of_match_table = of_match_ptr(ntc_match),
 714         },
 715         .probe = ntc_thermistor_probe,
 716         .id_table = ntc_thermistor_id,
 717 };
 718
 719 module_platform_driver(ntc_thermistor_driver);
 720
 721 MODULE_DESCRIPTION("NTC Thermistor Driver");
 722 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
 723 MODULE_LICENSE("GPL");
 724 MODULE_ALIAS("platform:ntc-thermistor");