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 #include <linux/fixp-arith.h> 17 18 #include <linux/platform_data/ntc_thermistor.h> 19 20 #include <linux/iio/consumer.h> 21 22 #include <linux/hwmon.h> 23 24 struct ntc_compensation { 25 int temp_c; 26 unsigned int ohm; 27 }; 28 29 /* 30 * Used as index in a zero-terminated array, holes not allowed so 31 * that NTC_LAST is the first empty array entry. 32 */ 33 enum { 34 NTC_B57330V2103, 35 NTC_B57891S0103, 36 NTC_NCP03WB473, 37 NTC_NCP03WF104, 38 NTC_NCP15WB473, 39 NTC_NCP15WL333, 40 NTC_NCP15XH103, 41 NTC_NCP18WB473, 42 NTC_NCP21WB473, 43 NTC_LAST, 44 }; 45 46 static const struct platform_device_id ntc_thermistor_id[] = { 47 [NTC_B57330V2103] = { "b57330v2103", TYPE_B57330V2103 }, 48 [NTC_B57891S0103] = { "b57891s0103", TYPE_B57891S0103 }, 49 [NTC_NCP03WB473] = { "ncp03wb473", TYPE_NCPXXWB473 }, 50 [NTC_NCP03WF104] = { "ncp03wf104", TYPE_NCPXXWF104 }, 51 [NTC_NCP15WB473] = { "ncp15wb473", TYPE_NCPXXWB473 }, 52 [NTC_NCP15WL333] = { "ncp15wl333", TYPE_NCPXXWL333 }, 53 [NTC_NCP15XH103] = { "ncp15xh103", TYPE_NCPXXXH103 }, 54 [NTC_NCP18WB473] = { "ncp18wb473", TYPE_NCPXXWB473 }, 55 [NTC_NCP21WB473] = { "ncp21wb473", TYPE_NCPXXWB473 }, 56 [NTC_LAST] = { }, 57 }; 58 59 /* 60 * A compensation table should be sorted by the values of .ohm 61 * in descending order. 62 * The following compensation tables are from the specification of Murata NTC 63 * Thermistors Datasheet 64 */ 65 static const struct ntc_compensation ncpXXwb473[] = { 66 { .temp_c = -40, .ohm = 1747920 }, 67 { .temp_c = -35, .ohm = 1245428 }, 68 { .temp_c = -30, .ohm = 898485 }, 69 { .temp_c = -25, .ohm = 655802 }, 70 { .temp_c = -20, .ohm = 483954 }, 71 { .temp_c = -15, .ohm = 360850 }, 72 { .temp_c = -10, .ohm = 271697 }, 73 { .temp_c = -5, .ohm = 206463 }, 74 { .temp_c = 0, .ohm = 158214 }, 75 { .temp_c = 5, .ohm = 122259 }, 76 { .temp_c = 10, .ohm = 95227 }, 77 { .temp_c = 15, .ohm = 74730 }, 78 { .temp_c = 20, .ohm = 59065 }, 79 { .temp_c = 25, .ohm = 47000 }, 80 { .temp_c = 30, .ohm = 37643 }, 81 { .temp_c = 35, .ohm = 30334 }, 82 { .temp_c = 40, .ohm = 24591 }, 83 { .temp_c = 45, .ohm = 20048 }, 84 { .temp_c = 50, .ohm = 16433 }, 85 { .temp_c = 55, .ohm = 13539 }, 86 { .temp_c = 60, .ohm = 11209 }, 87 { .temp_c = 65, .ohm = 9328 }, 88 { .temp_c = 70, .ohm = 7798 }, 89 { .temp_c = 75, .ohm = 6544 }, 90 { .temp_c = 80, .ohm = 5518 }, 91 { .temp_c = 85, .ohm = 4674 }, 92 { .temp_c = 90, .ohm = 3972 }, 93 { .temp_c = 95, .ohm = 3388 }, 94 { .temp_c = 100, .ohm = 2902 }, 95 { .temp_c = 105, .ohm = 2494 }, 96 { .temp_c = 110, .ohm = 2150 }, 97 { .temp_c = 115, .ohm = 1860 }, 98 { .temp_c = 120, .ohm = 1615 }, 99 { .temp_c = 125, .ohm = 1406 }, 100 }; 101 static const struct ntc_compensation ncpXXwl333[] = { 102 { .temp_c = -40, .ohm = 1610154 }, 103 { .temp_c = -35, .ohm = 1130850 }, 104 { .temp_c = -30, .ohm = 802609 }, 105 { .temp_c = -25, .ohm = 575385 }, 106 { .temp_c = -20, .ohm = 416464 }, 107 { .temp_c = -15, .ohm = 304219 }, 108 { .temp_c = -10, .ohm = 224193 }, 109 { .temp_c = -5, .ohm = 166623 }, 110 { .temp_c = 0, .ohm = 124850 }, 111 { .temp_c = 5, .ohm = 94287 }, 112 { .temp_c = 10, .ohm = 71747 }, 113 { .temp_c = 15, .ohm = 54996 }, 114 { .temp_c = 20, .ohm = 42455 }, 115 { .temp_c = 25, .ohm = 33000 }, 116 { .temp_c = 30, .ohm = 25822 }, 117 { .temp_c = 35, .ohm = 20335 }, 118 { .temp_c = 40, .ohm = 16115 }, 119 { .temp_c = 45, .ohm = 12849 }, 120 { .temp_c = 50, .ohm = 10306 }, 121 { .temp_c = 55, .ohm = 8314 }, 122 { .temp_c = 60, .ohm = 6746 }, 123 { .temp_c = 65, .ohm = 5503 }, 124 { .temp_c = 70, .ohm = 4513 }, 125 { .temp_c = 75, .ohm = 3721 }, 126 { .temp_c = 80, .ohm = 3084 }, 127 { .temp_c = 85, .ohm = 2569 }, 128 { .temp_c = 90, .ohm = 2151 }, 129 { .temp_c = 95, .ohm = 1809 }, 130 { .temp_c = 100, .ohm = 1529 }, 131 { .temp_c = 105, .ohm = 1299 }, 132 { .temp_c = 110, .ohm = 1108 }, 133 { .temp_c = 115, .ohm = 949 }, 134 { .temp_c = 120, .ohm = 817 }, 135 { .temp_c = 125, .ohm = 707 }, 136 }; 137 138 static const struct ntc_compensation ncpXXwf104[] = { 139 { .temp_c = -40, .ohm = 4397119 }, 140 { .temp_c = -35, .ohm = 3088599 }, 141 { .temp_c = -30, .ohm = 2197225 }, 142 { .temp_c = -25, .ohm = 1581881 }, 143 { .temp_c = -20, .ohm = 1151037 }, 144 { .temp_c = -15, .ohm = 846579 }, 145 { .temp_c = -10, .ohm = 628988 }, 146 { .temp_c = -5, .ohm = 471632 }, 147 { .temp_c = 0, .ohm = 357012 }, 148 { .temp_c = 5, .ohm = 272500 }, 149 { .temp_c = 10, .ohm = 209710 }, 150 { .temp_c = 15, .ohm = 162651 }, 151 { .temp_c = 20, .ohm = 127080 }, 152 { .temp_c = 25, .ohm = 100000 }, 153 { .temp_c = 30, .ohm = 79222 }, 154 { .temp_c = 35, .ohm = 63167 }, 155 { .temp_c = 40, .ohm = 50677 }, 156 { .temp_c = 45, .ohm = 40904 }, 157 { .temp_c = 50, .ohm = 33195 }, 158 { .temp_c = 55, .ohm = 27091 }, 159 { .temp_c = 60, .ohm = 22224 }, 160 { .temp_c = 65, .ohm = 18323 }, 161 { .temp_c = 70, .ohm = 15184 }, 162 { .temp_c = 75, .ohm = 12635 }, 163 { .temp_c = 80, .ohm = 10566 }, 164 { .temp_c = 85, .ohm = 8873 }, 165 { .temp_c = 90, .ohm = 7481 }, 166 { .temp_c = 95, .ohm = 6337 }, 167 { .temp_c = 100, .ohm = 5384 }, 168 { .temp_c = 105, .ohm = 4594 }, 169 { .temp_c = 110, .ohm = 3934 }, 170 { .temp_c = 115, .ohm = 3380 }, 171 { .temp_c = 120, .ohm = 2916 }, 172 { .temp_c = 125, .ohm = 2522 }, 173 }; 174 175 static const struct ntc_compensation ncpXXxh103[] = { 176 { .temp_c = -40, .ohm = 247565 }, 177 { .temp_c = -35, .ohm = 181742 }, 178 { .temp_c = -30, .ohm = 135128 }, 179 { .temp_c = -25, .ohm = 101678 }, 180 { .temp_c = -20, .ohm = 77373 }, 181 { .temp_c = -15, .ohm = 59504 }, 182 { .temp_c = -10, .ohm = 46222 }, 183 { .temp_c = -5, .ohm = 36244 }, 184 { .temp_c = 0, .ohm = 28674 }, 185 { .temp_c = 5, .ohm = 22878 }, 186 { .temp_c = 10, .ohm = 18399 }, 187 { .temp_c = 15, .ohm = 14910 }, 188 { .temp_c = 20, .ohm = 12169 }, 189 { .temp_c = 25, .ohm = 10000 }, 190 { .temp_c = 30, .ohm = 8271 }, 191 { .temp_c = 35, .ohm = 6883 }, 192 { .temp_c = 40, .ohm = 5762 }, 193 { .temp_c = 45, .ohm = 4851 }, 194 { .temp_c = 50, .ohm = 4105 }, 195 { .temp_c = 55, .ohm = 3492 }, 196 { .temp_c = 60, .ohm = 2985 }, 197 { .temp_c = 65, .ohm = 2563 }, 198 { .temp_c = 70, .ohm = 2211 }, 199 { .temp_c = 75, .ohm = 1915 }, 200 { .temp_c = 80, .ohm = 1666 }, 201 { .temp_c = 85, .ohm = 1454 }, 202 { .temp_c = 90, .ohm = 1275 }, 203 { .temp_c = 95, .ohm = 1121 }, 204 { .temp_c = 100, .ohm = 990 }, 205 { .temp_c = 105, .ohm = 876 }, 206 { .temp_c = 110, .ohm = 779 }, 207 { .temp_c = 115, .ohm = 694 }, 208 { .temp_c = 120, .ohm = 620 }, 209 { .temp_c = 125, .ohm = 556 }, 210 }; 211 212 /* 213 * The following compensation tables are from the specifications in EPCOS NTC 214 * Thermistors Datasheets 215 */ 216 static const struct ntc_compensation b57330v2103[] = { 217 { .temp_c = -40, .ohm = 190030 }, 218 { .temp_c = -35, .ohm = 145360 }, 219 { .temp_c = -30, .ohm = 112060 }, 220 { .temp_c = -25, .ohm = 87041 }, 221 { .temp_c = -20, .ohm = 68104 }, 222 { .temp_c = -15, .ohm = 53665 }, 223 { .temp_c = -10, .ohm = 42576 }, 224 { .temp_c = -5, .ohm = 34001 }, 225 { .temp_c = 0, .ohm = 27326 }, 226 { .temp_c = 5, .ohm = 22096 }, 227 { .temp_c = 10, .ohm = 17973 }, 228 { .temp_c = 15, .ohm = 14703 }, 229 { .temp_c = 20, .ohm = 12090 }, 230 { .temp_c = 25, .ohm = 10000 }, 231 { .temp_c = 30, .ohm = 8311 }, 232 { .temp_c = 35, .ohm = 6941 }, 233 { .temp_c = 40, .ohm = 5825 }, 234 { .temp_c = 45, .ohm = 4911 }, 235 { .temp_c = 50, .ohm = 4158 }, 236 { .temp_c = 55, .ohm = 3536 }, 237 { .temp_c = 60, .ohm = 3019 }, 238 { .temp_c = 65, .ohm = 2588 }, 239 { .temp_c = 70, .ohm = 2227 }, 240 { .temp_c = 75, .ohm = 1924 }, 241 { .temp_c = 80, .ohm = 1668 }, 242 { .temp_c = 85, .ohm = 1451 }, 243 { .temp_c = 90, .ohm = 1266 }, 244 { .temp_c = 95, .ohm = 1108 }, 245 { .temp_c = 100, .ohm = 973 }, 246 { .temp_c = 105, .ohm = 857 }, 247 { .temp_c = 110, .ohm = 757 }, 248 { .temp_c = 115, .ohm = 671 }, 249 { .temp_c = 120, .ohm = 596 }, 250 { .temp_c = 125, .ohm = 531 }, 251 }; 252 253 static const struct ntc_compensation b57891s0103[] = { 254 { .temp_c = -55.0, .ohm = 878900 }, 255 { .temp_c = -50.0, .ohm = 617590 }, 256 { .temp_c = -45.0, .ohm = 439340 }, 257 { .temp_c = -40.0, .ohm = 316180 }, 258 { .temp_c = -35.0, .ohm = 230060 }, 259 { .temp_c = -30.0, .ohm = 169150 }, 260 { .temp_c = -25.0, .ohm = 125550 }, 261 { .temp_c = -20.0, .ohm = 94143 }, 262 { .temp_c = -15.0, .ohm = 71172 }, 263 { .temp_c = -10.0, .ohm = 54308 }, 264 { .temp_c = -5.0, .ohm = 41505 }, 265 { .temp_c = 0.0, .ohm = 32014 }, 266 { .temp_c = 5.0, .ohm = 25011 }, 267 { .temp_c = 10.0, .ohm = 19691 }, 268 { .temp_c = 15.0, .ohm = 15618 }, 269 { .temp_c = 20.0, .ohm = 12474 }, 270 { .temp_c = 25.0, .ohm = 10000 }, 271 { .temp_c = 30.0, .ohm = 8080 }, 272 { .temp_c = 35.0, .ohm = 6569 }, 273 { .temp_c = 40.0, .ohm = 5372 }, 274 { .temp_c = 45.0, .ohm = 4424 }, 275 { .temp_c = 50.0, .ohm = 3661 }, 276 { .temp_c = 55.0, .ohm = 3039 }, 277 { .temp_c = 60.0, .ohm = 2536 }, 278 { .temp_c = 65.0, .ohm = 2128 }, 279 { .temp_c = 70.0, .ohm = 1794 }, 280 { .temp_c = 75.0, .ohm = 1518 }, 281 { .temp_c = 80.0, .ohm = 1290 }, 282 { .temp_c = 85.0, .ohm = 1100 }, 283 { .temp_c = 90.0, .ohm = 942 }, 284 { .temp_c = 95.0, .ohm = 809 }, 285 { .temp_c = 100.0, .ohm = 697 }, 286 { .temp_c = 105.0, .ohm = 604 }, 287 { .temp_c = 110.0, .ohm = 525 }, 288 { .temp_c = 115.0, .ohm = 457 }, 289 { .temp_c = 120.0, .ohm = 400 }, 290 { .temp_c = 125.0, .ohm = 351 }, 291 { .temp_c = 130.0, .ohm = 308 }, 292 { .temp_c = 135.0, .ohm = 272 }, 293 { .temp_c = 140.0, .ohm = 240 }, 294 { .temp_c = 145.0, .ohm = 213 }, 295 { .temp_c = 150.0, .ohm = 189 }, 296 { .temp_c = 155.0, .ohm = 168 }, 297 }; 298 299 struct ntc_type { 300 const struct ntc_compensation *comp; 301 int n_comp; 302 }; 303 304 #define NTC_TYPE(ntc, compensation) \ 305 [(ntc)] = { .comp = (compensation), .n_comp = ARRAY_SIZE(compensation) } 306 307 static const struct ntc_type ntc_type[] = { 308 NTC_TYPE(TYPE_B57330V2103, b57330v2103), 309 NTC_TYPE(TYPE_B57891S0103, b57891s0103), 310 NTC_TYPE(TYPE_NCPXXWB473, ncpXXwb473), 311 NTC_TYPE(TYPE_NCPXXWF104, ncpXXwf104), 312 NTC_TYPE(TYPE_NCPXXWL333, ncpXXwl333), 313 NTC_TYPE(TYPE_NCPXXXH103, ncpXXxh103), 314 }; 315 316 struct ntc_data { 317 struct ntc_thermistor_platform_data *pdata; 318 const struct ntc_compensation *comp; 319 int n_comp; 320 }; 321 322 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO) 323 static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata) 324 { 325 struct iio_channel *channel = pdata->chan; 326 int uv, ret; 327 328 ret = iio_read_channel_processed_scale(channel, &uv, 1000); 329 if (ret < 0) { 330 int raw; 331 332 /* 333 * This fallback uses a raw read and then 334 * assumes the ADC is 12 bits, scaling with 335 * a factor 1000 to get to microvolts. 336 */ 337 ret = iio_read_channel_raw(channel, &raw); 338 if (ret < 0) { 339 pr_err("read channel() error: %d\n", ret); 340 return ret; 341 } 342 ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000); 343 if (ret < 0) { 344 /* Assume 12 bit ADC with vref at pullup_uv */ 345 uv = (pdata->pullup_uv * (s64)raw) >> 12; 346 } 347 } 348 349 return uv; 350 } 351 352 static const struct of_device_id ntc_match[] = { 353 { .compatible = "epcos,b57330v2103", 354 .data = &ntc_thermistor_id[NTC_B57330V2103]}, 355 { .compatible = "epcos,b57891s0103", 356 .data = &ntc_thermistor_id[NTC_B57891S0103] }, 357 { .compatible = "murata,ncp03wb473", 358 .data = &ntc_thermistor_id[NTC_NCP03WB473] }, 359 { .compatible = "murata,ncp03wf104", 360 .data = &ntc_thermistor_id[NTC_NCP03WF104] }, 361 { .compatible = "murata,ncp15wb473", 362 .data = &ntc_thermistor_id[NTC_NCP15WB473] }, 363 { .compatible = "murata,ncp15wl333", 364 .data = &ntc_thermistor_id[NTC_NCP15WL333] }, 365 { .compatible = "murata,ncp15xh103", 366 .data = &ntc_thermistor_id[NTC_NCP15XH103] }, 367 { .compatible = "murata,ncp18wb473", 368 .data = &ntc_thermistor_id[NTC_NCP18WB473] }, 369 { .compatible = "murata,ncp21wb473", 370 .data = &ntc_thermistor_id[NTC_NCP21WB473] }, 371 372 /* Usage of vendor name "ntc" is deprecated */ 373 { .compatible = "ntc,ncp03wb473", 374 .data = &ntc_thermistor_id[NTC_NCP03WB473] }, 375 { .compatible = "ntc,ncp15wb473", 376 .data = &ntc_thermistor_id[NTC_NCP15WB473] }, 377 { .compatible = "ntc,ncp15wl333", 378 .data = &ntc_thermistor_id[NTC_NCP15WL333] }, 379 { .compatible = "ntc,ncp18wb473", 380 .data = &ntc_thermistor_id[NTC_NCP18WB473] }, 381 { .compatible = "ntc,ncp21wb473", 382 .data = &ntc_thermistor_id[NTC_NCP21WB473] }, 383 { }, 384 }; 385 MODULE_DEVICE_TABLE(of, ntc_match); 386 387 static struct ntc_thermistor_platform_data * 388 ntc_thermistor_parse_dt(struct device *dev) 389 { 390 struct iio_channel *chan; 391 enum iio_chan_type type; 392 struct device_node *np = dev->of_node; 393 struct ntc_thermistor_platform_data *pdata; 394 int ret; 395 396 if (!np) 397 return NULL; 398 399 pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); 400 if (!pdata) 401 return ERR_PTR(-ENOMEM); 402 403 chan = devm_iio_channel_get(dev, NULL); 404 if (IS_ERR(chan)) 405 return ERR_CAST(chan); 406 407 ret = iio_get_channel_type(chan, &type); 408 if (ret < 0) 409 return ERR_PTR(ret); 410 411 if (type != IIO_VOLTAGE) 412 return ERR_PTR(-EINVAL); 413 414 if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv)) 415 return ERR_PTR(-ENODEV); 416 if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm)) 417 return ERR_PTR(-ENODEV); 418 if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm)) 419 return ERR_PTR(-ENODEV); 420 421 if (of_find_property(np, "connected-positive", NULL)) 422 pdata->connect = NTC_CONNECTED_POSITIVE; 423 else /* status change should be possible if not always on. */ 424 pdata->connect = NTC_CONNECTED_GROUND; 425 426 pdata->chan = chan; 427 pdata->read_uv = ntc_adc_iio_read; 428 429 return pdata; 430 } 431 #else 432 static struct ntc_thermistor_platform_data * 433 ntc_thermistor_parse_dt(struct device *dev) 434 { 435 return NULL; 436 } 437 438 #define ntc_match NULL 439 440 #endif 441 442 static inline u64 div64_u64_safe(u64 dividend, u64 divisor) 443 { 444 if (divisor == 0 && dividend == 0) 445 return 0; 446 if (divisor == 0) 447 return UINT_MAX; 448 return div64_u64(dividend, divisor); 449 } 450 451 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv) 452 { 453 struct ntc_thermistor_platform_data *pdata = data->pdata; 454 u32 puv = pdata->pullup_uv; 455 u64 n, puo, pdo; 456 puo = pdata->pullup_ohm; 457 pdo = pdata->pulldown_ohm; 458 459 if (uv == 0) 460 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 461 INT_MAX : 0; 462 if (uv >= puv) 463 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 464 0 : INT_MAX; 465 466 if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0) 467 n = div_u64(pdo * (puv - uv), uv); 468 else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0) 469 n = div_u64(puo * uv, puv - uv); 470 else if (pdata->connect == NTC_CONNECTED_POSITIVE) 471 n = div64_u64_safe(pdo * puo * (puv - uv), 472 puo * uv - pdo * (puv - uv)); 473 else 474 n = div64_u64_safe(pdo * puo * uv, pdo * (puv - uv) - puo * uv); 475 476 if (n > INT_MAX) 477 n = INT_MAX; 478 return n; 479 } 480 481 static void lookup_comp(struct ntc_data *data, unsigned int ohm, 482 int *i_low, int *i_high) 483 { 484 int start, end, mid; 485 486 /* 487 * Handle special cases: Resistance is higher than or equal to 488 * resistance in first table entry, or resistance is lower or equal 489 * to resistance in last table entry. 490 * In these cases, return i_low == i_high, either pointing to the 491 * beginning or to the end of the table depending on the condition. 492 */ 493 if (ohm >= data->comp[0].ohm) { 494 *i_low = 0; 495 *i_high = 0; 496 return; 497 } 498 if (ohm <= data->comp[data->n_comp - 1].ohm) { 499 *i_low = data->n_comp - 1; 500 *i_high = data->n_comp - 1; 501 return; 502 } 503 504 /* Do a binary search on compensation table */ 505 start = 0; 506 end = data->n_comp; 507 while (start < end) { 508 mid = start + (end - start) / 2; 509 /* 510 * start <= mid < end 511 * data->comp[start].ohm > ohm >= data->comp[end].ohm 512 * 513 * We could check for "ohm == data->comp[mid].ohm" here, but 514 * that is a quite unlikely condition, and we would have to 515 * check again after updating start. Check it at the end instead 516 * for simplicity. 517 */ 518 if (ohm >= data->comp[mid].ohm) { 519 end = mid; 520 } else { 521 start = mid + 1; 522 /* 523 * ohm >= data->comp[start].ohm might be true here, 524 * since we set start to mid + 1. In that case, we are 525 * done. We could keep going, but the condition is quite 526 * likely to occur, so it is worth checking for it. 527 */ 528 if (ohm >= data->comp[start].ohm) 529 end = start; 530 } 531 /* 532 * start <= end 533 * data->comp[start].ohm >= ohm >= data->comp[end].ohm 534 */ 535 } 536 /* 537 * start == end 538 * ohm >= data->comp[end].ohm 539 */ 540 *i_low = end; 541 if (ohm == data->comp[end].ohm) 542 *i_high = end; 543 else 544 *i_high = end - 1; 545 } 546 547 static int get_temp_mc(struct ntc_data *data, unsigned int ohm) 548 { 549 int low, high; 550 int temp; 551 552 lookup_comp(data, ohm, &low, &high); 553 /* 554 * First multiplying the table temperatures with 1000 to get to 555 * millicentigrades (which is what we want) and then interpolating 556 * will give the best precision. 557 */ 558 temp = fixp_linear_interpolate(data->comp[low].ohm, 559 data->comp[low].temp_c * 1000, 560 data->comp[high].ohm, 561 data->comp[high].temp_c * 1000, 562 ohm); 563 return temp; 564 } 565 566 static int ntc_thermistor_get_ohm(struct ntc_data *data) 567 { 568 int read_uv; 569 570 if (data->pdata->read_ohm) 571 return data->pdata->read_ohm(); 572 573 if (data->pdata->read_uv) { 574 read_uv = data->pdata->read_uv(data->pdata); 575 if (read_uv < 0) 576 return read_uv; 577 return get_ohm_of_thermistor(data, read_uv); 578 } 579 return -EINVAL; 580 } 581 582 static int ntc_read(struct device *dev, enum hwmon_sensor_types type, 583 u32 attr, int channel, long *val) 584 { 585 struct ntc_data *data = dev_get_drvdata(dev); 586 int ohm; 587 588 switch (type) { 589 case hwmon_temp: 590 switch (attr) { 591 case hwmon_temp_input: 592 ohm = ntc_thermistor_get_ohm(data); 593 if (ohm < 0) 594 return ohm; 595 *val = get_temp_mc(data, ohm); 596 return 0; 597 case hwmon_temp_type: 598 *val = 4; 599 return 0; 600 default: 601 break; 602 } 603 break; 604 default: 605 break; 606 } 607 return -EINVAL; 608 } 609 610 static umode_t ntc_is_visible(const void *data, enum hwmon_sensor_types type, 611 u32 attr, int channel) 612 { 613 if (type == hwmon_temp) { 614 switch (attr) { 615 case hwmon_temp_input: 616 case hwmon_temp_type: 617 return 0444; 618 default: 619 break; 620 } 621 } 622 return 0; 623 } 624 625 static const struct hwmon_channel_info *ntc_info[] = { 626 HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ), 627 HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_TYPE), 628 NULL 629 }; 630 631 static const struct hwmon_ops ntc_hwmon_ops = { 632 .is_visible = ntc_is_visible, 633 .read = ntc_read, 634 }; 635 636 static const struct hwmon_chip_info ntc_chip_info = { 637 .ops = &ntc_hwmon_ops, 638 .info = ntc_info, 639 }; 640 641 static int ntc_thermistor_probe(struct platform_device *pdev) 642 { 643 struct device *dev = &pdev->dev; 644 const struct of_device_id *of_id = 645 of_match_device(of_match_ptr(ntc_match), dev); 646 const struct platform_device_id *pdev_id; 647 struct ntc_thermistor_platform_data *pdata; 648 struct device *hwmon_dev; 649 struct ntc_data *data; 650 651 pdata = ntc_thermistor_parse_dt(dev); 652 if (IS_ERR(pdata)) 653 return PTR_ERR(pdata); 654 else if (pdata == NULL) 655 pdata = dev_get_platdata(dev); 656 657 if (!pdata) { 658 dev_err(dev, "No platform init data supplied.\n"); 659 return -ENODEV; 660 } 661 662 /* Either one of the two is required. */ 663 if (!pdata->read_uv && !pdata->read_ohm) { 664 dev_err(dev, 665 "Both read_uv and read_ohm missing. Need either one of the two.\n"); 666 return -EINVAL; 667 } 668 669 if (pdata->read_uv && pdata->read_ohm) { 670 dev_warn(dev, 671 "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n"); 672 pdata->read_uv = NULL; 673 } 674 675 if (pdata->read_uv && (pdata->pullup_uv == 0 || 676 (pdata->pullup_ohm == 0 && pdata->connect == 677 NTC_CONNECTED_GROUND) || 678 (pdata->pulldown_ohm == 0 && pdata->connect == 679 NTC_CONNECTED_POSITIVE) || 680 (pdata->connect != NTC_CONNECTED_POSITIVE && 681 pdata->connect != NTC_CONNECTED_GROUND))) { 682 dev_err(dev, "Required data to use read_uv not supplied.\n"); 683 return -EINVAL; 684 } 685 686 data = devm_kzalloc(dev, sizeof(struct ntc_data), GFP_KERNEL); 687 if (!data) 688 return -ENOMEM; 689 690 pdev_id = of_id ? of_id->data : platform_get_device_id(pdev); 691 692 data->pdata = pdata; 693 694 if (pdev_id->driver_data >= ARRAY_SIZE(ntc_type)) { 695 dev_err(dev, "Unknown device type: %lu(%s)\n", 696 pdev_id->driver_data, pdev_id->name); 697 return -EINVAL; 698 } 699 700 data->comp = ntc_type[pdev_id->driver_data].comp; 701 data->n_comp = ntc_type[pdev_id->driver_data].n_comp; 702 703 hwmon_dev = devm_hwmon_device_register_with_info(dev, pdev_id->name, 704 data, &ntc_chip_info, 705 NULL); 706 if (IS_ERR(hwmon_dev)) { 707 dev_err(dev, "unable to register as hwmon device.\n"); 708 return PTR_ERR(hwmon_dev); 709 } 710 711 dev_info(dev, "Thermistor type: %s successfully probed.\n", 712 pdev_id->name); 713 714 return 0; 715 } 716 717 static struct platform_driver ntc_thermistor_driver = { 718 .driver = { 719 .name = "ntc-thermistor", 720 .of_match_table = of_match_ptr(ntc_match), 721 }, 722 .probe = ntc_thermistor_probe, 723 .id_table = ntc_thermistor_id, 724 }; 725 726 module_platform_driver(ntc_thermistor_driver); 727 728 MODULE_DESCRIPTION("NTC Thermistor Driver"); 729 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 730 MODULE_LICENSE("GPL"); 731 MODULE_ALIAS("platform:ntc-thermistor"); 732