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/platform_device.h> 13 #include <linux/err.h> 14 #include <linux/of.h> 15 #include <linux/of_device.h> 16 17 #include <linux/platform_data/ntc_thermistor.h> 18 19 #include <linux/iio/consumer.h> 20 21 #include <linux/hwmon.h> 22 23 struct ntc_compensation { 24 int temp_c; 25 unsigned int ohm; 26 }; 27 28 /* 29 * Used as index in a zero-terminated array, holes not allowed so 30 * that NTC_LAST is the first empty array entry. 31 */ 32 enum { 33 NTC_B57330V2103, 34 NTC_B57891S0103, 35 NTC_NCP03WB473, 36 NTC_NCP03WF104, 37 NTC_NCP15WB473, 38 NTC_NCP15WL333, 39 NTC_NCP15XH103, 40 NTC_NCP18WB473, 41 NTC_NCP21WB473, 42 NTC_LAST, 43 }; 44 45 static const struct platform_device_id ntc_thermistor_id[] = { 46 [NTC_B57330V2103] = { "b57330v2103", TYPE_B57330V2103 }, 47 [NTC_B57891S0103] = { "b57891s0103", TYPE_B57891S0103 }, 48 [NTC_NCP03WB473] = { "ncp03wb473", TYPE_NCPXXWB473 }, 49 [NTC_NCP03WF104] = { "ncp03wf104", TYPE_NCPXXWF104 }, 50 [NTC_NCP15WB473] = { "ncp15wb473", TYPE_NCPXXWB473 }, 51 [NTC_NCP15WL333] = { "ncp15wl333", TYPE_NCPXXWL333 }, 52 [NTC_NCP15XH103] = { "ncp15xh103", TYPE_NCPXXXH103 }, 53 [NTC_NCP18WB473] = { "ncp18wb473", TYPE_NCPXXWB473 }, 54 [NTC_NCP21WB473] = { "ncp21wb473", TYPE_NCPXXWB473 }, 55 [NTC_LAST] = { }, 56 }; 57 58 /* 59 * A compensation table should be sorted by the values of .ohm 60 * in descending order. 61 * The following compensation tables are from the specification of Murata NTC 62 * Thermistors Datasheet 63 */ 64 static const struct ntc_compensation ncpXXwb473[] = { 65 { .temp_c = -40, .ohm = 1747920 }, 66 { .temp_c = -35, .ohm = 1245428 }, 67 { .temp_c = -30, .ohm = 898485 }, 68 { .temp_c = -25, .ohm = 655802 }, 69 { .temp_c = -20, .ohm = 483954 }, 70 { .temp_c = -15, .ohm = 360850 }, 71 { .temp_c = -10, .ohm = 271697 }, 72 { .temp_c = -5, .ohm = 206463 }, 73 { .temp_c = 0, .ohm = 158214 }, 74 { .temp_c = 5, .ohm = 122259 }, 75 { .temp_c = 10, .ohm = 95227 }, 76 { .temp_c = 15, .ohm = 74730 }, 77 { .temp_c = 20, .ohm = 59065 }, 78 { .temp_c = 25, .ohm = 47000 }, 79 { .temp_c = 30, .ohm = 37643 }, 80 { .temp_c = 35, .ohm = 30334 }, 81 { .temp_c = 40, .ohm = 24591 }, 82 { .temp_c = 45, .ohm = 20048 }, 83 { .temp_c = 50, .ohm = 16433 }, 84 { .temp_c = 55, .ohm = 13539 }, 85 { .temp_c = 60, .ohm = 11209 }, 86 { .temp_c = 65, .ohm = 9328 }, 87 { .temp_c = 70, .ohm = 7798 }, 88 { .temp_c = 75, .ohm = 6544 }, 89 { .temp_c = 80, .ohm = 5518 }, 90 { .temp_c = 85, .ohm = 4674 }, 91 { .temp_c = 90, .ohm = 3972 }, 92 { .temp_c = 95, .ohm = 3388 }, 93 { .temp_c = 100, .ohm = 2902 }, 94 { .temp_c = 105, .ohm = 2494 }, 95 { .temp_c = 110, .ohm = 2150 }, 96 { .temp_c = 115, .ohm = 1860 }, 97 { .temp_c = 120, .ohm = 1615 }, 98 { .temp_c = 125, .ohm = 1406 }, 99 }; 100 static const struct ntc_compensation ncpXXwl333[] = { 101 { .temp_c = -40, .ohm = 1610154 }, 102 { .temp_c = -35, .ohm = 1130850 }, 103 { .temp_c = -30, .ohm = 802609 }, 104 { .temp_c = -25, .ohm = 575385 }, 105 { .temp_c = -20, .ohm = 416464 }, 106 { .temp_c = -15, .ohm = 304219 }, 107 { .temp_c = -10, .ohm = 224193 }, 108 { .temp_c = -5, .ohm = 166623 }, 109 { .temp_c = 0, .ohm = 124850 }, 110 { .temp_c = 5, .ohm = 94287 }, 111 { .temp_c = 10, .ohm = 71747 }, 112 { .temp_c = 15, .ohm = 54996 }, 113 { .temp_c = 20, .ohm = 42455 }, 114 { .temp_c = 25, .ohm = 33000 }, 115 { .temp_c = 30, .ohm = 25822 }, 116 { .temp_c = 35, .ohm = 20335 }, 117 { .temp_c = 40, .ohm = 16115 }, 118 { .temp_c = 45, .ohm = 12849 }, 119 { .temp_c = 50, .ohm = 10306 }, 120 { .temp_c = 55, .ohm = 8314 }, 121 { .temp_c = 60, .ohm = 6746 }, 122 { .temp_c = 65, .ohm = 5503 }, 123 { .temp_c = 70, .ohm = 4513 }, 124 { .temp_c = 75, .ohm = 3721 }, 125 { .temp_c = 80, .ohm = 3084 }, 126 { .temp_c = 85, .ohm = 2569 }, 127 { .temp_c = 90, .ohm = 2151 }, 128 { .temp_c = 95, .ohm = 1809 }, 129 { .temp_c = 100, .ohm = 1529 }, 130 { .temp_c = 105, .ohm = 1299 }, 131 { .temp_c = 110, .ohm = 1108 }, 132 { .temp_c = 115, .ohm = 949 }, 133 { .temp_c = 120, .ohm = 817 }, 134 { .temp_c = 125, .ohm = 707 }, 135 }; 136 137 static const struct ntc_compensation ncpXXwf104[] = { 138 { .temp_c = -40, .ohm = 4397119 }, 139 { .temp_c = -35, .ohm = 3088599 }, 140 { .temp_c = -30, .ohm = 2197225 }, 141 { .temp_c = -25, .ohm = 1581881 }, 142 { .temp_c = -20, .ohm = 1151037 }, 143 { .temp_c = -15, .ohm = 846579 }, 144 { .temp_c = -10, .ohm = 628988 }, 145 { .temp_c = -5, .ohm = 471632 }, 146 { .temp_c = 0, .ohm = 357012 }, 147 { .temp_c = 5, .ohm = 272500 }, 148 { .temp_c = 10, .ohm = 209710 }, 149 { .temp_c = 15, .ohm = 162651 }, 150 { .temp_c = 20, .ohm = 127080 }, 151 { .temp_c = 25, .ohm = 100000 }, 152 { .temp_c = 30, .ohm = 79222 }, 153 { .temp_c = 35, .ohm = 63167 }, 154 { .temp_c = 40, .ohm = 50677 }, 155 { .temp_c = 45, .ohm = 40904 }, 156 { .temp_c = 50, .ohm = 33195 }, 157 { .temp_c = 55, .ohm = 27091 }, 158 { .temp_c = 60, .ohm = 22224 }, 159 { .temp_c = 65, .ohm = 18323 }, 160 { .temp_c = 70, .ohm = 15184 }, 161 { .temp_c = 75, .ohm = 12635 }, 162 { .temp_c = 80, .ohm = 10566 }, 163 { .temp_c = 85, .ohm = 8873 }, 164 { .temp_c = 90, .ohm = 7481 }, 165 { .temp_c = 95, .ohm = 6337 }, 166 { .temp_c = 100, .ohm = 5384 }, 167 { .temp_c = 105, .ohm = 4594 }, 168 { .temp_c = 110, .ohm = 3934 }, 169 { .temp_c = 115, .ohm = 3380 }, 170 { .temp_c = 120, .ohm = 2916 }, 171 { .temp_c = 125, .ohm = 2522 }, 172 }; 173 174 static const struct ntc_compensation ncpXXxh103[] = { 175 { .temp_c = -40, .ohm = 247565 }, 176 { .temp_c = -35, .ohm = 181742 }, 177 { .temp_c = -30, .ohm = 135128 }, 178 { .temp_c = -25, .ohm = 101678 }, 179 { .temp_c = -20, .ohm = 77373 }, 180 { .temp_c = -15, .ohm = 59504 }, 181 { .temp_c = -10, .ohm = 46222 }, 182 { .temp_c = -5, .ohm = 36244 }, 183 { .temp_c = 0, .ohm = 28674 }, 184 { .temp_c = 5, .ohm = 22878 }, 185 { .temp_c = 10, .ohm = 18399 }, 186 { .temp_c = 15, .ohm = 14910 }, 187 { .temp_c = 20, .ohm = 12169 }, 188 { .temp_c = 25, .ohm = 10000 }, 189 { .temp_c = 30, .ohm = 8271 }, 190 { .temp_c = 35, .ohm = 6883 }, 191 { .temp_c = 40, .ohm = 5762 }, 192 { .temp_c = 45, .ohm = 4851 }, 193 { .temp_c = 50, .ohm = 4105 }, 194 { .temp_c = 55, .ohm = 3492 }, 195 { .temp_c = 60, .ohm = 2985 }, 196 { .temp_c = 65, .ohm = 2563 }, 197 { .temp_c = 70, .ohm = 2211 }, 198 { .temp_c = 75, .ohm = 1915 }, 199 { .temp_c = 80, .ohm = 1666 }, 200 { .temp_c = 85, .ohm = 1454 }, 201 { .temp_c = 90, .ohm = 1275 }, 202 { .temp_c = 95, .ohm = 1121 }, 203 { .temp_c = 100, .ohm = 990 }, 204 { .temp_c = 105, .ohm = 876 }, 205 { .temp_c = 110, .ohm = 779 }, 206 { .temp_c = 115, .ohm = 694 }, 207 { .temp_c = 120, .ohm = 620 }, 208 { .temp_c = 125, .ohm = 556 }, 209 }; 210 211 /* 212 * The following compensation tables are from the specifications in EPCOS NTC 213 * Thermistors Datasheets 214 */ 215 static const struct ntc_compensation b57330v2103[] = { 216 { .temp_c = -40, .ohm = 190030 }, 217 { .temp_c = -35, .ohm = 145360 }, 218 { .temp_c = -30, .ohm = 112060 }, 219 { .temp_c = -25, .ohm = 87041 }, 220 { .temp_c = -20, .ohm = 68104 }, 221 { .temp_c = -15, .ohm = 53665 }, 222 { .temp_c = -10, .ohm = 42576 }, 223 { .temp_c = -5, .ohm = 34001 }, 224 { .temp_c = 0, .ohm = 27326 }, 225 { .temp_c = 5, .ohm = 22096 }, 226 { .temp_c = 10, .ohm = 17973 }, 227 { .temp_c = 15, .ohm = 14703 }, 228 { .temp_c = 20, .ohm = 12090 }, 229 { .temp_c = 25, .ohm = 10000 }, 230 { .temp_c = 30, .ohm = 8311 }, 231 { .temp_c = 35, .ohm = 6941 }, 232 { .temp_c = 40, .ohm = 5825 }, 233 { .temp_c = 45, .ohm = 4911 }, 234 { .temp_c = 50, .ohm = 4158 }, 235 { .temp_c = 55, .ohm = 3536 }, 236 { .temp_c = 60, .ohm = 3019 }, 237 { .temp_c = 65, .ohm = 2588 }, 238 { .temp_c = 70, .ohm = 2227 }, 239 { .temp_c = 75, .ohm = 1924 }, 240 { .temp_c = 80, .ohm = 1668 }, 241 { .temp_c = 85, .ohm = 1451 }, 242 { .temp_c = 90, .ohm = 1266 }, 243 { .temp_c = 95, .ohm = 1108 }, 244 { .temp_c = 100, .ohm = 973 }, 245 { .temp_c = 105, .ohm = 857 }, 246 { .temp_c = 110, .ohm = 757 }, 247 { .temp_c = 115, .ohm = 671 }, 248 { .temp_c = 120, .ohm = 596 }, 249 { .temp_c = 125, .ohm = 531 }, 250 }; 251 252 static const struct ntc_compensation b57891s0103[] = { 253 { .temp_c = -55.0, .ohm = 878900 }, 254 { .temp_c = -50.0, .ohm = 617590 }, 255 { .temp_c = -45.0, .ohm = 439340 }, 256 { .temp_c = -40.0, .ohm = 316180 }, 257 { .temp_c = -35.0, .ohm = 230060 }, 258 { .temp_c = -30.0, .ohm = 169150 }, 259 { .temp_c = -25.0, .ohm = 125550 }, 260 { .temp_c = -20.0, .ohm = 94143 }, 261 { .temp_c = -15.0, .ohm = 71172 }, 262 { .temp_c = -10.0, .ohm = 54308 }, 263 { .temp_c = -5.0, .ohm = 41505 }, 264 { .temp_c = 0.0, .ohm = 32014 }, 265 { .temp_c = 5.0, .ohm = 25011 }, 266 { .temp_c = 10.0, .ohm = 19691 }, 267 { .temp_c = 15.0, .ohm = 15618 }, 268 { .temp_c = 20.0, .ohm = 12474 }, 269 { .temp_c = 25.0, .ohm = 10000 }, 270 { .temp_c = 30.0, .ohm = 8080 }, 271 { .temp_c = 35.0, .ohm = 6569 }, 272 { .temp_c = 40.0, .ohm = 5372 }, 273 { .temp_c = 45.0, .ohm = 4424 }, 274 { .temp_c = 50.0, .ohm = 3661 }, 275 { .temp_c = 55.0, .ohm = 3039 }, 276 { .temp_c = 60.0, .ohm = 2536 }, 277 { .temp_c = 65.0, .ohm = 2128 }, 278 { .temp_c = 70.0, .ohm = 1794 }, 279 { .temp_c = 75.0, .ohm = 1518 }, 280 { .temp_c = 80.0, .ohm = 1290 }, 281 { .temp_c = 85.0, .ohm = 1100 }, 282 { .temp_c = 90.0, .ohm = 942 }, 283 { .temp_c = 95.0, .ohm = 809 }, 284 { .temp_c = 100.0, .ohm = 697 }, 285 { .temp_c = 105.0, .ohm = 604 }, 286 { .temp_c = 110.0, .ohm = 525 }, 287 { .temp_c = 115.0, .ohm = 457 }, 288 { .temp_c = 120.0, .ohm = 400 }, 289 { .temp_c = 125.0, .ohm = 351 }, 290 { .temp_c = 130.0, .ohm = 308 }, 291 { .temp_c = 135.0, .ohm = 272 }, 292 { .temp_c = 140.0, .ohm = 240 }, 293 { .temp_c = 145.0, .ohm = 213 }, 294 { .temp_c = 150.0, .ohm = 189 }, 295 { .temp_c = 155.0, .ohm = 168 }, 296 }; 297 298 struct ntc_type { 299 const struct ntc_compensation *comp; 300 int n_comp; 301 }; 302 303 #define NTC_TYPE(ntc, compensation) \ 304 [(ntc)] = { .comp = (compensation), .n_comp = ARRAY_SIZE(compensation) } 305 306 static const struct ntc_type ntc_type[] = { 307 NTC_TYPE(TYPE_B57330V2103, b57330v2103), 308 NTC_TYPE(TYPE_B57891S0103, b57891s0103), 309 NTC_TYPE(TYPE_NCPXXWB473, ncpXXwb473), 310 NTC_TYPE(TYPE_NCPXXWF104, ncpXXwf104), 311 NTC_TYPE(TYPE_NCPXXWL333, ncpXXwl333), 312 NTC_TYPE(TYPE_NCPXXXH103, ncpXXxh103), 313 }; 314 315 struct ntc_data { 316 struct ntc_thermistor_platform_data *pdata; 317 const struct ntc_compensation *comp; 318 int n_comp; 319 }; 320 321 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO) 322 static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata) 323 { 324 struct iio_channel *channel = pdata->chan; 325 int uv, ret; 326 327 ret = iio_read_channel_processed_scale(channel, &uv, 1000); 328 if (ret < 0) { 329 int raw; 330 331 /* 332 * This fallback uses a raw read and then 333 * assumes the ADC is 12 bits, scaling with 334 * a factor 1000 to get to microvolts. 335 */ 336 ret = iio_read_channel_raw(channel, &raw); 337 if (ret < 0) { 338 pr_err("read channel() error: %d\n", ret); 339 return ret; 340 } 341 ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000); 342 if (ret < 0) { 343 /* Assume 12 bit ADC with vref at pullup_uv */ 344 uv = (pdata->pullup_uv * (s64)raw) >> 12; 345 } 346 } 347 348 return uv; 349 } 350 351 static const struct of_device_id ntc_match[] = { 352 { .compatible = "epcos,b57330v2103", 353 .data = &ntc_thermistor_id[NTC_B57330V2103]}, 354 { .compatible = "epcos,b57891s0103", 355 .data = &ntc_thermistor_id[NTC_B57891S0103] }, 356 { .compatible = "murata,ncp03wb473", 357 .data = &ntc_thermistor_id[NTC_NCP03WB473] }, 358 { .compatible = "murata,ncp03wf104", 359 .data = &ntc_thermistor_id[NTC_NCP03WF104] }, 360 { .compatible = "murata,ncp15wb473", 361 .data = &ntc_thermistor_id[NTC_NCP15WB473] }, 362 { .compatible = "murata,ncp15wl333", 363 .data = &ntc_thermistor_id[NTC_NCP15WL333] }, 364 { .compatible = "murata,ncp15xh103", 365 .data = &ntc_thermistor_id[NTC_NCP15XH103] }, 366 { .compatible = "murata,ncp18wb473", 367 .data = &ntc_thermistor_id[NTC_NCP18WB473] }, 368 { .compatible = "murata,ncp21wb473", 369 .data = &ntc_thermistor_id[NTC_NCP21WB473] }, 370 371 /* Usage of vendor name "ntc" is deprecated */ 372 { .compatible = "ntc,ncp03wb473", 373 .data = &ntc_thermistor_id[NTC_NCP03WB473] }, 374 { .compatible = "ntc,ncp15wb473", 375 .data = &ntc_thermistor_id[NTC_NCP15WB473] }, 376 { .compatible = "ntc,ncp15wl333", 377 .data = &ntc_thermistor_id[NTC_NCP15WL333] }, 378 { .compatible = "ntc,ncp18wb473", 379 .data = &ntc_thermistor_id[NTC_NCP18WB473] }, 380 { .compatible = "ntc,ncp21wb473", 381 .data = &ntc_thermistor_id[NTC_NCP21WB473] }, 382 { }, 383 }; 384 MODULE_DEVICE_TABLE(of, ntc_match); 385 386 static struct ntc_thermistor_platform_data * 387 ntc_thermistor_parse_dt(struct device *dev) 388 { 389 struct iio_channel *chan; 390 enum iio_chan_type type; 391 struct device_node *np = dev->of_node; 392 struct ntc_thermistor_platform_data *pdata; 393 int ret; 394 395 if (!np) 396 return NULL; 397 398 pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); 399 if (!pdata) 400 return ERR_PTR(-ENOMEM); 401 402 chan = devm_iio_channel_get(dev, NULL); 403 if (IS_ERR(chan)) 404 return ERR_CAST(chan); 405 406 ret = iio_get_channel_type(chan, &type); 407 if (ret < 0) 408 return ERR_PTR(ret); 409 410 if (type != IIO_VOLTAGE) 411 return ERR_PTR(-EINVAL); 412 413 if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv)) 414 return ERR_PTR(-ENODEV); 415 if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm)) 416 return ERR_PTR(-ENODEV); 417 if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm)) 418 return ERR_PTR(-ENODEV); 419 420 if (of_find_property(np, "connected-positive", NULL)) 421 pdata->connect = NTC_CONNECTED_POSITIVE; 422 else /* status change should be possible if not always on. */ 423 pdata->connect = NTC_CONNECTED_GROUND; 424 425 pdata->chan = chan; 426 pdata->read_uv = ntc_adc_iio_read; 427 428 return pdata; 429 } 430 #else 431 static struct ntc_thermistor_platform_data * 432 ntc_thermistor_parse_dt(struct device *dev) 433 { 434 return NULL; 435 } 436 437 #define ntc_match NULL 438 439 #endif 440 441 static inline u64 div64_u64_safe(u64 dividend, u64 divisor) 442 { 443 if (divisor == 0 && dividend == 0) 444 return 0; 445 if (divisor == 0) 446 return UINT_MAX; 447 return div64_u64(dividend, divisor); 448 } 449 450 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv) 451 { 452 struct ntc_thermistor_platform_data *pdata = data->pdata; 453 u32 puv = pdata->pullup_uv; 454 u64 n, puo, pdo; 455 puo = pdata->pullup_ohm; 456 pdo = pdata->pulldown_ohm; 457 458 if (uv == 0) 459 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 460 INT_MAX : 0; 461 if (uv >= puv) 462 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 463 0 : INT_MAX; 464 465 if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0) 466 n = div_u64(pdo * (puv - uv), uv); 467 else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0) 468 n = div_u64(puo * uv, puv - uv); 469 else if (pdata->connect == NTC_CONNECTED_POSITIVE) 470 n = div64_u64_safe(pdo * puo * (puv - uv), 471 puo * uv - pdo * (puv - uv)); 472 else 473 n = div64_u64_safe(pdo * puo * uv, pdo * (puv - uv) - puo * uv); 474 475 if (n > INT_MAX) 476 n = INT_MAX; 477 return n; 478 } 479 480 static void lookup_comp(struct ntc_data *data, unsigned int ohm, 481 int *i_low, int *i_high) 482 { 483 int start, end, mid; 484 485 /* 486 * Handle special cases: Resistance is higher than or equal to 487 * resistance in first table entry, or resistance is lower or equal 488 * to resistance in last table entry. 489 * In these cases, return i_low == i_high, either pointing to the 490 * beginning or to the end of the table depending on the condition. 491 */ 492 if (ohm >= data->comp[0].ohm) { 493 *i_low = 0; 494 *i_high = 0; 495 return; 496 } 497 if (ohm <= data->comp[data->n_comp - 1].ohm) { 498 *i_low = data->n_comp - 1; 499 *i_high = data->n_comp - 1; 500 return; 501 } 502 503 /* Do a binary search on compensation table */ 504 start = 0; 505 end = data->n_comp; 506 while (start < end) { 507 mid = start + (end - start) / 2; 508 /* 509 * start <= mid < end 510 * data->comp[start].ohm > ohm >= data->comp[end].ohm 511 * 512 * We could check for "ohm == data->comp[mid].ohm" here, but 513 * that is a quite unlikely condition, and we would have to 514 * check again after updating start. Check it at the end instead 515 * for simplicity. 516 */ 517 if (ohm >= data->comp[mid].ohm) { 518 end = mid; 519 } else { 520 start = mid + 1; 521 /* 522 * ohm >= data->comp[start].ohm might be true here, 523 * since we set start to mid + 1. In that case, we are 524 * done. We could keep going, but the condition is quite 525 * likely to occur, so it is worth checking for it. 526 */ 527 if (ohm >= data->comp[start].ohm) 528 end = start; 529 } 530 /* 531 * start <= end 532 * data->comp[start].ohm >= ohm >= data->comp[end].ohm 533 */ 534 } 535 /* 536 * start == end 537 * ohm >= data->comp[end].ohm 538 */ 539 *i_low = end; 540 if (ohm == data->comp[end].ohm) 541 *i_high = end; 542 else 543 *i_high = end - 1; 544 } 545 546 static int get_temp_mc(struct ntc_data *data, unsigned int ohm) 547 { 548 int low, high; 549 int temp; 550 551 lookup_comp(data, ohm, &low, &high); 552 if (low == high) { 553 /* Unable to use linear approximation */ 554 temp = data->comp[low].temp_c * 1000; 555 } else { 556 temp = data->comp[low].temp_c * 1000 + 557 ((data->comp[high].temp_c - data->comp[low].temp_c) * 558 1000 * ((int)ohm - (int)data->comp[low].ohm)) / 559 ((int)data->comp[high].ohm - (int)data->comp[low].ohm); 560 } 561 return temp; 562 } 563 564 static int ntc_thermistor_get_ohm(struct ntc_data *data) 565 { 566 int read_uv; 567 568 if (data->pdata->read_ohm) 569 return data->pdata->read_ohm(); 570 571 if (data->pdata->read_uv) { 572 read_uv = data->pdata->read_uv(data->pdata); 573 if (read_uv < 0) 574 return read_uv; 575 return get_ohm_of_thermistor(data, read_uv); 576 } 577 return -EINVAL; 578 } 579 580 static int ntc_read(struct device *dev, enum hwmon_sensor_types type, 581 u32 attr, int channel, long *val) 582 { 583 struct ntc_data *data = dev_get_drvdata(dev); 584 int ohm; 585 586 switch (type) { 587 case hwmon_temp: 588 switch (attr) { 589 case hwmon_temp_input: 590 ohm = ntc_thermistor_get_ohm(data); 591 if (ohm < 0) 592 return ohm; 593 *val = get_temp_mc(data, ohm); 594 return 0; 595 case hwmon_temp_type: 596 *val = 4; 597 return 0; 598 default: 599 break; 600 } 601 break; 602 default: 603 break; 604 } 605 return -EINVAL; 606 } 607 608 static umode_t ntc_is_visible(const void *data, enum hwmon_sensor_types type, 609 u32 attr, int channel) 610 { 611 if (type == hwmon_temp) { 612 switch (attr) { 613 case hwmon_temp_input: 614 case hwmon_temp_type: 615 return 0444; 616 default: 617 break; 618 } 619 } 620 return 0; 621 } 622 623 static const struct hwmon_channel_info *ntc_info[] = { 624 HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ), 625 HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_TYPE), 626 NULL 627 }; 628 629 static const struct hwmon_ops ntc_hwmon_ops = { 630 .is_visible = ntc_is_visible, 631 .read = ntc_read, 632 }; 633 634 static const struct hwmon_chip_info ntc_chip_info = { 635 .ops = &ntc_hwmon_ops, 636 .info = ntc_info, 637 }; 638 639 static int ntc_thermistor_probe(struct platform_device *pdev) 640 { 641 struct device *dev = &pdev->dev; 642 const struct of_device_id *of_id = 643 of_match_device(of_match_ptr(ntc_match), dev); 644 const struct platform_device_id *pdev_id; 645 struct ntc_thermistor_platform_data *pdata; 646 struct device *hwmon_dev; 647 struct ntc_data *data; 648 649 pdata = ntc_thermistor_parse_dt(dev); 650 if (IS_ERR(pdata)) 651 return PTR_ERR(pdata); 652 else if (pdata == NULL) 653 pdata = dev_get_platdata(dev); 654 655 if (!pdata) { 656 dev_err(dev, "No platform init data supplied.\n"); 657 return -ENODEV; 658 } 659 660 /* Either one of the two is required. */ 661 if (!pdata->read_uv && !pdata->read_ohm) { 662 dev_err(dev, 663 "Both read_uv and read_ohm missing. Need either one of the two.\n"); 664 return -EINVAL; 665 } 666 667 if (pdata->read_uv && pdata->read_ohm) { 668 dev_warn(dev, 669 "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n"); 670 pdata->read_uv = NULL; 671 } 672 673 if (pdata->read_uv && (pdata->pullup_uv == 0 || 674 (pdata->pullup_ohm == 0 && pdata->connect == 675 NTC_CONNECTED_GROUND) || 676 (pdata->pulldown_ohm == 0 && pdata->connect == 677 NTC_CONNECTED_POSITIVE) || 678 (pdata->connect != NTC_CONNECTED_POSITIVE && 679 pdata->connect != NTC_CONNECTED_GROUND))) { 680 dev_err(dev, "Required data to use read_uv not supplied.\n"); 681 return -EINVAL; 682 } 683 684 data = devm_kzalloc(dev, sizeof(struct ntc_data), GFP_KERNEL); 685 if (!data) 686 return -ENOMEM; 687 688 pdev_id = of_id ? of_id->data : platform_get_device_id(pdev); 689 690 data->pdata = pdata; 691 692 if (pdev_id->driver_data >= ARRAY_SIZE(ntc_type)) { 693 dev_err(dev, "Unknown device type: %lu(%s)\n", 694 pdev_id->driver_data, pdev_id->name); 695 return -EINVAL; 696 } 697 698 data->comp = ntc_type[pdev_id->driver_data].comp; 699 data->n_comp = ntc_type[pdev_id->driver_data].n_comp; 700 701 hwmon_dev = devm_hwmon_device_register_with_info(dev, pdev_id->name, 702 data, &ntc_chip_info, 703 NULL); 704 if (IS_ERR(hwmon_dev)) { 705 dev_err(dev, "unable to register as hwmon device.\n"); 706 return PTR_ERR(hwmon_dev); 707 } 708 709 dev_info(dev, "Thermistor type: %s successfully probed.\n", 710 pdev_id->name); 711 712 return 0; 713 } 714 715 static struct platform_driver ntc_thermistor_driver = { 716 .driver = { 717 .name = "ntc-thermistor", 718 .of_match_table = of_match_ptr(ntc_match), 719 }, 720 .probe = ntc_thermistor_probe, 721 .id_table = ntc_thermistor_id, 722 }; 723 724 module_platform_driver(ntc_thermistor_driver); 725 726 MODULE_DESCRIPTION("NTC Thermistor Driver"); 727 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 728 MODULE_LICENSE("GPL"); 729 MODULE_ALIAS("platform:ntc-thermistor"); 730