1 /* 2 * ntc_thermistor.c - NTC Thermistors 3 * 4 * Copyright (C) 2010 Samsung Electronics 5 * MyungJoo Ham <myungjoo.ham@samsung.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 * 21 */ 22 23 #include <linux/slab.h> 24 #include <linux/module.h> 25 #include <linux/pm_runtime.h> 26 #include <linux/math64.h> 27 #include <linux/platform_device.h> 28 #include <linux/err.h> 29 #include <linux/of.h> 30 #include <linux/of_device.h> 31 32 #include <linux/platform_data/ntc_thermistor.h> 33 34 #include <linux/iio/iio.h> 35 #include <linux/iio/machine.h> 36 #include <linux/iio/driver.h> 37 #include <linux/iio/consumer.h> 38 39 #include <linux/hwmon.h> 40 #include <linux/hwmon-sysfs.h> 41 #include <linux/thermal.h> 42 43 struct ntc_compensation { 44 int temp_c; 45 unsigned int ohm; 46 }; 47 48 /* 49 * Used as index in a zero-terminated array, holes not allowed so 50 * that NTC_LAST is the first empty array entry. 51 */ 52 enum { 53 NTC_B57330V2103, 54 NTC_B57891S0103, 55 NTC_NCP03WB473, 56 NTC_NCP03WF104, 57 NTC_NCP15WB473, 58 NTC_NCP15WL333, 59 NTC_NCP15XH103, 60 NTC_NCP18WB473, 61 NTC_NCP21WB473, 62 NTC_LAST, 63 }; 64 65 static const struct platform_device_id ntc_thermistor_id[] = { 66 [NTC_B57330V2103] = { "b57330v2103", TYPE_B57330V2103 }, 67 [NTC_B57891S0103] = { "b57891s0103", TYPE_B57891S0103 }, 68 [NTC_NCP03WB473] = { "ncp03wb473", TYPE_NCPXXWB473 }, 69 [NTC_NCP03WF104] = { "ncp03wf104", TYPE_NCPXXWF104 }, 70 [NTC_NCP15WB473] = { "ncp15wb473", TYPE_NCPXXWB473 }, 71 [NTC_NCP15WL333] = { "ncp15wl333", TYPE_NCPXXWL333 }, 72 [NTC_NCP15XH103] = { "ncp15xh103", TYPE_NCPXXXH103 }, 73 [NTC_NCP18WB473] = { "ncp18wb473", TYPE_NCPXXWB473 }, 74 [NTC_NCP21WB473] = { "ncp21wb473", TYPE_NCPXXWB473 }, 75 [NTC_LAST] = { }, 76 }; 77 78 /* 79 * A compensation table should be sorted by the values of .ohm 80 * in descending order. 81 * The following compensation tables are from the specification of Murata NTC 82 * Thermistors Datasheet 83 */ 84 static const struct ntc_compensation ncpXXwb473[] = { 85 { .temp_c = -40, .ohm = 1747920 }, 86 { .temp_c = -35, .ohm = 1245428 }, 87 { .temp_c = -30, .ohm = 898485 }, 88 { .temp_c = -25, .ohm = 655802 }, 89 { .temp_c = -20, .ohm = 483954 }, 90 { .temp_c = -15, .ohm = 360850 }, 91 { .temp_c = -10, .ohm = 271697 }, 92 { .temp_c = -5, .ohm = 206463 }, 93 { .temp_c = 0, .ohm = 158214 }, 94 { .temp_c = 5, .ohm = 122259 }, 95 { .temp_c = 10, .ohm = 95227 }, 96 { .temp_c = 15, .ohm = 74730 }, 97 { .temp_c = 20, .ohm = 59065 }, 98 { .temp_c = 25, .ohm = 47000 }, 99 { .temp_c = 30, .ohm = 37643 }, 100 { .temp_c = 35, .ohm = 30334 }, 101 { .temp_c = 40, .ohm = 24591 }, 102 { .temp_c = 45, .ohm = 20048 }, 103 { .temp_c = 50, .ohm = 16433 }, 104 { .temp_c = 55, .ohm = 13539 }, 105 { .temp_c = 60, .ohm = 11209 }, 106 { .temp_c = 65, .ohm = 9328 }, 107 { .temp_c = 70, .ohm = 7798 }, 108 { .temp_c = 75, .ohm = 6544 }, 109 { .temp_c = 80, .ohm = 5518 }, 110 { .temp_c = 85, .ohm = 4674 }, 111 { .temp_c = 90, .ohm = 3972 }, 112 { .temp_c = 95, .ohm = 3388 }, 113 { .temp_c = 100, .ohm = 2902 }, 114 { .temp_c = 105, .ohm = 2494 }, 115 { .temp_c = 110, .ohm = 2150 }, 116 { .temp_c = 115, .ohm = 1860 }, 117 { .temp_c = 120, .ohm = 1615 }, 118 { .temp_c = 125, .ohm = 1406 }, 119 }; 120 static const struct ntc_compensation ncpXXwl333[] = { 121 { .temp_c = -40, .ohm = 1610154 }, 122 { .temp_c = -35, .ohm = 1130850 }, 123 { .temp_c = -30, .ohm = 802609 }, 124 { .temp_c = -25, .ohm = 575385 }, 125 { .temp_c = -20, .ohm = 416464 }, 126 { .temp_c = -15, .ohm = 304219 }, 127 { .temp_c = -10, .ohm = 224193 }, 128 { .temp_c = -5, .ohm = 166623 }, 129 { .temp_c = 0, .ohm = 124850 }, 130 { .temp_c = 5, .ohm = 94287 }, 131 { .temp_c = 10, .ohm = 71747 }, 132 { .temp_c = 15, .ohm = 54996 }, 133 { .temp_c = 20, .ohm = 42455 }, 134 { .temp_c = 25, .ohm = 33000 }, 135 { .temp_c = 30, .ohm = 25822 }, 136 { .temp_c = 35, .ohm = 20335 }, 137 { .temp_c = 40, .ohm = 16115 }, 138 { .temp_c = 45, .ohm = 12849 }, 139 { .temp_c = 50, .ohm = 10306 }, 140 { .temp_c = 55, .ohm = 8314 }, 141 { .temp_c = 60, .ohm = 6746 }, 142 { .temp_c = 65, .ohm = 5503 }, 143 { .temp_c = 70, .ohm = 4513 }, 144 { .temp_c = 75, .ohm = 3721 }, 145 { .temp_c = 80, .ohm = 3084 }, 146 { .temp_c = 85, .ohm = 2569 }, 147 { .temp_c = 90, .ohm = 2151 }, 148 { .temp_c = 95, .ohm = 1809 }, 149 { .temp_c = 100, .ohm = 1529 }, 150 { .temp_c = 105, .ohm = 1299 }, 151 { .temp_c = 110, .ohm = 1108 }, 152 { .temp_c = 115, .ohm = 949 }, 153 { .temp_c = 120, .ohm = 817 }, 154 { .temp_c = 125, .ohm = 707 }, 155 }; 156 157 static const struct ntc_compensation ncpXXwf104[] = { 158 { .temp_c = -40, .ohm = 4397119 }, 159 { .temp_c = -35, .ohm = 3088599 }, 160 { .temp_c = -30, .ohm = 2197225 }, 161 { .temp_c = -25, .ohm = 1581881 }, 162 { .temp_c = -20, .ohm = 1151037 }, 163 { .temp_c = -15, .ohm = 846579 }, 164 { .temp_c = -10, .ohm = 628988 }, 165 { .temp_c = -5, .ohm = 471632 }, 166 { .temp_c = 0, .ohm = 357012 }, 167 { .temp_c = 5, .ohm = 272500 }, 168 { .temp_c = 10, .ohm = 209710 }, 169 { .temp_c = 15, .ohm = 162651 }, 170 { .temp_c = 20, .ohm = 127080 }, 171 { .temp_c = 25, .ohm = 100000 }, 172 { .temp_c = 30, .ohm = 79222 }, 173 { .temp_c = 35, .ohm = 63167 }, 174 { .temp_c = 40, .ohm = 50677 }, 175 { .temp_c = 45, .ohm = 40904 }, 176 { .temp_c = 50, .ohm = 33195 }, 177 { .temp_c = 55, .ohm = 27091 }, 178 { .temp_c = 60, .ohm = 22224 }, 179 { .temp_c = 65, .ohm = 18323 }, 180 { .temp_c = 70, .ohm = 15184 }, 181 { .temp_c = 75, .ohm = 12635 }, 182 { .temp_c = 80, .ohm = 10566 }, 183 { .temp_c = 85, .ohm = 8873 }, 184 { .temp_c = 90, .ohm = 7481 }, 185 { .temp_c = 95, .ohm = 6337 }, 186 { .temp_c = 100, .ohm = 5384 }, 187 { .temp_c = 105, .ohm = 4594 }, 188 { .temp_c = 110, .ohm = 3934 }, 189 { .temp_c = 115, .ohm = 3380 }, 190 { .temp_c = 120, .ohm = 2916 }, 191 { .temp_c = 125, .ohm = 2522 }, 192 }; 193 194 static const struct ntc_compensation ncpXXxh103[] = { 195 { .temp_c = -40, .ohm = 247565 }, 196 { .temp_c = -35, .ohm = 181742 }, 197 { .temp_c = -30, .ohm = 135128 }, 198 { .temp_c = -25, .ohm = 101678 }, 199 { .temp_c = -20, .ohm = 77373 }, 200 { .temp_c = -15, .ohm = 59504 }, 201 { .temp_c = -10, .ohm = 46222 }, 202 { .temp_c = -5, .ohm = 36244 }, 203 { .temp_c = 0, .ohm = 28674 }, 204 { .temp_c = 5, .ohm = 22878 }, 205 { .temp_c = 10, .ohm = 18399 }, 206 { .temp_c = 15, .ohm = 14910 }, 207 { .temp_c = 20, .ohm = 12169 }, 208 { .temp_c = 25, .ohm = 10000 }, 209 { .temp_c = 30, .ohm = 8271 }, 210 { .temp_c = 35, .ohm = 6883 }, 211 { .temp_c = 40, .ohm = 5762 }, 212 { .temp_c = 45, .ohm = 4851 }, 213 { .temp_c = 50, .ohm = 4105 }, 214 { .temp_c = 55, .ohm = 3492 }, 215 { .temp_c = 60, .ohm = 2985 }, 216 { .temp_c = 65, .ohm = 2563 }, 217 { .temp_c = 70, .ohm = 2211 }, 218 { .temp_c = 75, .ohm = 1915 }, 219 { .temp_c = 80, .ohm = 1666 }, 220 { .temp_c = 85, .ohm = 1454 }, 221 { .temp_c = 90, .ohm = 1275 }, 222 { .temp_c = 95, .ohm = 1121 }, 223 { .temp_c = 100, .ohm = 990 }, 224 { .temp_c = 105, .ohm = 876 }, 225 { .temp_c = 110, .ohm = 779 }, 226 { .temp_c = 115, .ohm = 694 }, 227 { .temp_c = 120, .ohm = 620 }, 228 { .temp_c = 125, .ohm = 556 }, 229 }; 230 231 /* 232 * The following compensation tables are from the specifications in EPCOS NTC 233 * Thermistors Datasheets 234 */ 235 static const struct ntc_compensation b57330v2103[] = { 236 { .temp_c = -40, .ohm = 190030 }, 237 { .temp_c = -35, .ohm = 145360 }, 238 { .temp_c = -30, .ohm = 112060 }, 239 { .temp_c = -25, .ohm = 87041 }, 240 { .temp_c = -20, .ohm = 68104 }, 241 { .temp_c = -15, .ohm = 53665 }, 242 { .temp_c = -10, .ohm = 42576 }, 243 { .temp_c = -5, .ohm = 34001 }, 244 { .temp_c = 0, .ohm = 27326 }, 245 { .temp_c = 5, .ohm = 22096 }, 246 { .temp_c = 10, .ohm = 17973 }, 247 { .temp_c = 15, .ohm = 14703 }, 248 { .temp_c = 20, .ohm = 12090 }, 249 { .temp_c = 25, .ohm = 10000 }, 250 { .temp_c = 30, .ohm = 8311 }, 251 { .temp_c = 35, .ohm = 6941 }, 252 { .temp_c = 40, .ohm = 5825 }, 253 { .temp_c = 45, .ohm = 4911 }, 254 { .temp_c = 50, .ohm = 4158 }, 255 { .temp_c = 55, .ohm = 3536 }, 256 { .temp_c = 60, .ohm = 3019 }, 257 { .temp_c = 65, .ohm = 2588 }, 258 { .temp_c = 70, .ohm = 2227 }, 259 { .temp_c = 75, .ohm = 1924 }, 260 { .temp_c = 80, .ohm = 1668 }, 261 { .temp_c = 85, .ohm = 1451 }, 262 { .temp_c = 90, .ohm = 1266 }, 263 { .temp_c = 95, .ohm = 1108 }, 264 { .temp_c = 100, .ohm = 973 }, 265 { .temp_c = 105, .ohm = 857 }, 266 { .temp_c = 110, .ohm = 757 }, 267 { .temp_c = 115, .ohm = 671 }, 268 { .temp_c = 120, .ohm = 596 }, 269 { .temp_c = 125, .ohm = 531 }, 270 }; 271 272 static const struct ntc_compensation b57891s0103[] = { 273 { .temp_c = -55.0, .ohm = 878900 }, 274 { .temp_c = -50.0, .ohm = 617590 }, 275 { .temp_c = -45.0, .ohm = 439340 }, 276 { .temp_c = -40.0, .ohm = 316180 }, 277 { .temp_c = -35.0, .ohm = 230060 }, 278 { .temp_c = -30.0, .ohm = 169150 }, 279 { .temp_c = -25.0, .ohm = 125550 }, 280 { .temp_c = -20.0, .ohm = 94143 }, 281 { .temp_c = -15.0, .ohm = 71172 }, 282 { .temp_c = -10.0, .ohm = 54308 }, 283 { .temp_c = -5.0, .ohm = 41505 }, 284 { .temp_c = 0.0, .ohm = 32014 }, 285 { .temp_c = 5.0, .ohm = 25011 }, 286 { .temp_c = 10.0, .ohm = 19691 }, 287 { .temp_c = 15.0, .ohm = 15618 }, 288 { .temp_c = 20.0, .ohm = 12474 }, 289 { .temp_c = 25.0, .ohm = 10000 }, 290 { .temp_c = 30.0, .ohm = 8080 }, 291 { .temp_c = 35.0, .ohm = 6569 }, 292 { .temp_c = 40.0, .ohm = 5372 }, 293 { .temp_c = 45.0, .ohm = 4424 }, 294 { .temp_c = 50.0, .ohm = 3661 }, 295 { .temp_c = 55.0, .ohm = 3039 }, 296 { .temp_c = 60.0, .ohm = 2536 }, 297 { .temp_c = 65.0, .ohm = 2128 }, 298 { .temp_c = 70.0, .ohm = 1794 }, 299 { .temp_c = 75.0, .ohm = 1518 }, 300 { .temp_c = 80.0, .ohm = 1290 }, 301 { .temp_c = 85.0, .ohm = 1100 }, 302 { .temp_c = 90.0, .ohm = 942 }, 303 { .temp_c = 95.0, .ohm = 809 }, 304 { .temp_c = 100.0, .ohm = 697 }, 305 { .temp_c = 105.0, .ohm = 604 }, 306 { .temp_c = 110.0, .ohm = 525 }, 307 { .temp_c = 115.0, .ohm = 457 }, 308 { .temp_c = 120.0, .ohm = 400 }, 309 { .temp_c = 125.0, .ohm = 351 }, 310 { .temp_c = 130.0, .ohm = 308 }, 311 { .temp_c = 135.0, .ohm = 272 }, 312 { .temp_c = 140.0, .ohm = 240 }, 313 { .temp_c = 145.0, .ohm = 213 }, 314 { .temp_c = 150.0, .ohm = 189 }, 315 { .temp_c = 155.0, .ohm = 168 }, 316 }; 317 318 struct ntc_type { 319 const struct ntc_compensation *comp; 320 int n_comp; 321 }; 322 323 #define NTC_TYPE(ntc, compensation) \ 324 [(ntc)] = { .comp = (compensation), .n_comp = ARRAY_SIZE(compensation) } 325 326 static const struct ntc_type ntc_type[] = { 327 NTC_TYPE(TYPE_B57330V2103, b57330v2103), 328 NTC_TYPE(TYPE_B57891S0103, b57891s0103), 329 NTC_TYPE(TYPE_NCPXXWB473, ncpXXwb473), 330 NTC_TYPE(TYPE_NCPXXWF104, ncpXXwf104), 331 NTC_TYPE(TYPE_NCPXXWL333, ncpXXwl333), 332 NTC_TYPE(TYPE_NCPXXXH103, ncpXXxh103), 333 }; 334 335 struct ntc_data { 336 struct ntc_thermistor_platform_data *pdata; 337 const struct ntc_compensation *comp; 338 int n_comp; 339 }; 340 341 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO) 342 static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata) 343 { 344 struct iio_channel *channel = pdata->chan; 345 int raw, uv, ret; 346 347 ret = iio_read_channel_raw(channel, &raw); 348 if (ret < 0) { 349 pr_err("read channel() error: %d\n", ret); 350 return ret; 351 } 352 353 ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000); 354 if (ret < 0) { 355 /* Assume 12 bit ADC with vref at pullup_uv */ 356 uv = (pdata->pullup_uv * (s64)raw) >> 12; 357 } 358 359 return uv; 360 } 361 362 static const struct of_device_id ntc_match[] = { 363 { .compatible = "epcos,b57330v2103", 364 .data = &ntc_thermistor_id[NTC_B57330V2103]}, 365 { .compatible = "epcos,b57891s0103", 366 .data = &ntc_thermistor_id[NTC_B57891S0103] }, 367 { .compatible = "murata,ncp03wb473", 368 .data = &ntc_thermistor_id[NTC_NCP03WB473] }, 369 { .compatible = "murata,ncp03wf104", 370 .data = &ntc_thermistor_id[NTC_NCP03WF104] }, 371 { .compatible = "murata,ncp15wb473", 372 .data = &ntc_thermistor_id[NTC_NCP15WB473] }, 373 { .compatible = "murata,ncp15wl333", 374 .data = &ntc_thermistor_id[NTC_NCP15WL333] }, 375 { .compatible = "murata,ncp15xh103", 376 .data = &ntc_thermistor_id[NTC_NCP15XH103] }, 377 { .compatible = "murata,ncp18wb473", 378 .data = &ntc_thermistor_id[NTC_NCP18WB473] }, 379 { .compatible = "murata,ncp21wb473", 380 .data = &ntc_thermistor_id[NTC_NCP21WB473] }, 381 382 /* Usage of vendor name "ntc" is deprecated */ 383 { .compatible = "ntc,ncp03wb473", 384 .data = &ntc_thermistor_id[NTC_NCP03WB473] }, 385 { .compatible = "ntc,ncp15wb473", 386 .data = &ntc_thermistor_id[NTC_NCP15WB473] }, 387 { .compatible = "ntc,ncp15wl333", 388 .data = &ntc_thermistor_id[NTC_NCP15WL333] }, 389 { .compatible = "ntc,ncp18wb473", 390 .data = &ntc_thermistor_id[NTC_NCP18WB473] }, 391 { .compatible = "ntc,ncp21wb473", 392 .data = &ntc_thermistor_id[NTC_NCP21WB473] }, 393 { }, 394 }; 395 MODULE_DEVICE_TABLE(of, ntc_match); 396 397 static struct ntc_thermistor_platform_data * 398 ntc_thermistor_parse_dt(struct device *dev) 399 { 400 struct iio_channel *chan; 401 enum iio_chan_type type; 402 struct device_node *np = dev->of_node; 403 struct ntc_thermistor_platform_data *pdata; 404 int ret; 405 406 if (!np) 407 return NULL; 408 409 pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); 410 if (!pdata) 411 return ERR_PTR(-ENOMEM); 412 413 chan = devm_iio_channel_get(dev, NULL); 414 if (IS_ERR(chan)) 415 return ERR_CAST(chan); 416 417 ret = iio_get_channel_type(chan, &type); 418 if (ret < 0) 419 return ERR_PTR(ret); 420 421 if (type != IIO_VOLTAGE) 422 return ERR_PTR(-EINVAL); 423 424 if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv)) 425 return ERR_PTR(-ENODEV); 426 if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm)) 427 return ERR_PTR(-ENODEV); 428 if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm)) 429 return ERR_PTR(-ENODEV); 430 431 if (of_find_property(np, "connected-positive", NULL)) 432 pdata->connect = NTC_CONNECTED_POSITIVE; 433 else /* status change should be possible if not always on. */ 434 pdata->connect = NTC_CONNECTED_GROUND; 435 436 pdata->chan = chan; 437 pdata->read_uv = ntc_adc_iio_read; 438 439 return pdata; 440 } 441 #else 442 static struct ntc_thermistor_platform_data * 443 ntc_thermistor_parse_dt(struct device *dev) 444 { 445 return NULL; 446 } 447 448 #define ntc_match NULL 449 450 #endif 451 452 static inline u64 div64_u64_safe(u64 dividend, u64 divisor) 453 { 454 if (divisor == 0 && dividend == 0) 455 return 0; 456 if (divisor == 0) 457 return UINT_MAX; 458 return div64_u64(dividend, divisor); 459 } 460 461 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv) 462 { 463 struct ntc_thermistor_platform_data *pdata = data->pdata; 464 u32 puv = pdata->pullup_uv; 465 u64 n, puo, pdo; 466 puo = pdata->pullup_ohm; 467 pdo = pdata->pulldown_ohm; 468 469 if (uv == 0) 470 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 471 INT_MAX : 0; 472 if (uv >= puv) 473 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 474 0 : INT_MAX; 475 476 if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0) 477 n = div_u64(pdo * (puv - uv), uv); 478 else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0) 479 n = div_u64(puo * uv, puv - uv); 480 else if (pdata->connect == NTC_CONNECTED_POSITIVE) 481 n = div64_u64_safe(pdo * puo * (puv - uv), 482 puo * uv - pdo * (puv - uv)); 483 else 484 n = div64_u64_safe(pdo * puo * uv, pdo * (puv - uv) - puo * uv); 485 486 if (n > INT_MAX) 487 n = INT_MAX; 488 return n; 489 } 490 491 static void lookup_comp(struct ntc_data *data, unsigned int ohm, 492 int *i_low, int *i_high) 493 { 494 int start, end, mid; 495 496 /* 497 * Handle special cases: Resistance is higher than or equal to 498 * resistance in first table entry, or resistance is lower or equal 499 * to resistance in last table entry. 500 * In these cases, return i_low == i_high, either pointing to the 501 * beginning or to the end of the table depending on the condition. 502 */ 503 if (ohm >= data->comp[0].ohm) { 504 *i_low = 0; 505 *i_high = 0; 506 return; 507 } 508 if (ohm <= data->comp[data->n_comp - 1].ohm) { 509 *i_low = data->n_comp - 1; 510 *i_high = data->n_comp - 1; 511 return; 512 } 513 514 /* Do a binary search on compensation table */ 515 start = 0; 516 end = data->n_comp; 517 while (start < end) { 518 mid = start + (end - start) / 2; 519 /* 520 * start <= mid < end 521 * data->comp[start].ohm > ohm >= data->comp[end].ohm 522 * 523 * We could check for "ohm == data->comp[mid].ohm" here, but 524 * that is a quite unlikely condition, and we would have to 525 * check again after updating start. Check it at the end instead 526 * for simplicity. 527 */ 528 if (ohm >= data->comp[mid].ohm) { 529 end = mid; 530 } else { 531 start = mid + 1; 532 /* 533 * ohm >= data->comp[start].ohm might be true here, 534 * since we set start to mid + 1. In that case, we are 535 * done. We could keep going, but the condition is quite 536 * likely to occur, so it is worth checking for it. 537 */ 538 if (ohm >= data->comp[start].ohm) 539 end = start; 540 } 541 /* 542 * start <= end 543 * data->comp[start].ohm >= ohm >= data->comp[end].ohm 544 */ 545 } 546 /* 547 * start == end 548 * ohm >= data->comp[end].ohm 549 */ 550 *i_low = end; 551 if (ohm == data->comp[end].ohm) 552 *i_high = end; 553 else 554 *i_high = end - 1; 555 } 556 557 static int get_temp_mc(struct ntc_data *data, unsigned int ohm) 558 { 559 int low, high; 560 int temp; 561 562 lookup_comp(data, ohm, &low, &high); 563 if (low == high) { 564 /* Unable to use linear approximation */ 565 temp = data->comp[low].temp_c * 1000; 566 } else { 567 temp = data->comp[low].temp_c * 1000 + 568 ((data->comp[high].temp_c - data->comp[low].temp_c) * 569 1000 * ((int)ohm - (int)data->comp[low].ohm)) / 570 ((int)data->comp[high].ohm - (int)data->comp[low].ohm); 571 } 572 return temp; 573 } 574 575 static int ntc_thermistor_get_ohm(struct ntc_data *data) 576 { 577 int read_uv; 578 579 if (data->pdata->read_ohm) 580 return data->pdata->read_ohm(); 581 582 if (data->pdata->read_uv) { 583 read_uv = data->pdata->read_uv(data->pdata); 584 if (read_uv < 0) 585 return read_uv; 586 return get_ohm_of_thermistor(data, read_uv); 587 } 588 return -EINVAL; 589 } 590 591 static int ntc_read_temp(void *data, int *temp) 592 { 593 int ohm; 594 595 ohm = ntc_thermistor_get_ohm(data); 596 if (ohm < 0) 597 return ohm; 598 599 *temp = get_temp_mc(data, ohm); 600 601 return 0; 602 } 603 604 static ssize_t ntc_type_show(struct device *dev, 605 struct device_attribute *attr, char *buf) 606 { 607 return sprintf(buf, "4\n"); 608 } 609 610 static ssize_t ntc_temp_show(struct device *dev, 611 struct device_attribute *attr, char *buf) 612 { 613 struct ntc_data *data = dev_get_drvdata(dev); 614 int ohm; 615 616 ohm = ntc_thermistor_get_ohm(data); 617 if (ohm < 0) 618 return ohm; 619 620 return sprintf(buf, "%d\n", get_temp_mc(data, ohm)); 621 } 622 623 static SENSOR_DEVICE_ATTR_RO(temp1_type, ntc_type, 0); 624 static SENSOR_DEVICE_ATTR_RO(temp1_input, ntc_temp, 0); 625 626 static struct attribute *ntc_attrs[] = { 627 &sensor_dev_attr_temp1_type.dev_attr.attr, 628 &sensor_dev_attr_temp1_input.dev_attr.attr, 629 NULL, 630 }; 631 ATTRIBUTE_GROUPS(ntc); 632 633 static const struct thermal_zone_of_device_ops ntc_of_thermal_ops = { 634 .get_temp = ntc_read_temp, 635 }; 636 637 static int ntc_thermistor_probe(struct platform_device *pdev) 638 { 639 struct thermal_zone_device *tz; 640 struct device *dev = &pdev->dev; 641 const struct of_device_id *of_id = 642 of_match_device(of_match_ptr(ntc_match), dev); 643 const struct platform_device_id *pdev_id; 644 struct ntc_thermistor_platform_data *pdata; 645 struct device *hwmon_dev; 646 struct ntc_data *data; 647 648 pdata = ntc_thermistor_parse_dt(dev); 649 if (IS_ERR(pdata)) 650 return PTR_ERR(pdata); 651 else if (pdata == NULL) 652 pdata = dev_get_platdata(dev); 653 654 if (!pdata) { 655 dev_err(dev, "No platform init data supplied.\n"); 656 return -ENODEV; 657 } 658 659 /* Either one of the two is required. */ 660 if (!pdata->read_uv && !pdata->read_ohm) { 661 dev_err(dev, 662 "Both read_uv and read_ohm missing. Need either one of the two.\n"); 663 return -EINVAL; 664 } 665 666 if (pdata->read_uv && pdata->read_ohm) { 667 dev_warn(dev, 668 "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n"); 669 pdata->read_uv = NULL; 670 } 671 672 if (pdata->read_uv && (pdata->pullup_uv == 0 || 673 (pdata->pullup_ohm == 0 && pdata->connect == 674 NTC_CONNECTED_GROUND) || 675 (pdata->pulldown_ohm == 0 && pdata->connect == 676 NTC_CONNECTED_POSITIVE) || 677 (pdata->connect != NTC_CONNECTED_POSITIVE && 678 pdata->connect != NTC_CONNECTED_GROUND))) { 679 dev_err(dev, "Required data to use read_uv not supplied.\n"); 680 return -EINVAL; 681 } 682 683 data = devm_kzalloc(dev, sizeof(struct ntc_data), GFP_KERNEL); 684 if (!data) 685 return -ENOMEM; 686 687 pdev_id = of_id ? of_id->data : platform_get_device_id(pdev); 688 689 data->pdata = pdata; 690 691 if (pdev_id->driver_data >= ARRAY_SIZE(ntc_type)) { 692 dev_err(dev, "Unknown device type: %lu(%s)\n", 693 pdev_id->driver_data, pdev_id->name); 694 return -EINVAL; 695 } 696 697 data->comp = ntc_type[pdev_id->driver_data].comp; 698 data->n_comp = ntc_type[pdev_id->driver_data].n_comp; 699 700 hwmon_dev = devm_hwmon_device_register_with_groups(dev, pdev_id->name, 701 data, ntc_groups); 702 if (IS_ERR(hwmon_dev)) { 703 dev_err(dev, "unable to register as hwmon device.\n"); 704 return PTR_ERR(hwmon_dev); 705 } 706 707 dev_info(dev, "Thermistor type: %s successfully probed.\n", 708 pdev_id->name); 709 710 tz = devm_thermal_zone_of_sensor_register(dev, 0, data, 711 &ntc_of_thermal_ops); 712 if (IS_ERR(tz)) 713 dev_dbg(dev, "Failed to register to thermal fw.\n"); 714 715 return 0; 716 } 717 718 static struct platform_driver ntc_thermistor_driver = { 719 .driver = { 720 .name = "ntc-thermistor", 721 .of_match_table = of_match_ptr(ntc_match), 722 }, 723 .probe = ntc_thermistor_probe, 724 .id_table = ntc_thermistor_id, 725 }; 726 727 module_platform_driver(ntc_thermistor_driver); 728 729 MODULE_DESCRIPTION("NTC Thermistor Driver"); 730 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 731 MODULE_LICENSE("GPL"); 732 MODULE_ALIAS("platform:ntc-thermistor"); 733