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 41 struct ntc_compensation { 42 int temp_c; 43 unsigned int ohm; 44 }; 45 46 /* 47 * Used as index in a zero-terminated array, holes not allowed so 48 * that NTC_LAST is the first empty array entry. 49 */ 50 enum { 51 NTC_B57330V2103, 52 NTC_B57891S0103, 53 NTC_NCP03WB473, 54 NTC_NCP03WF104, 55 NTC_NCP15WB473, 56 NTC_NCP15WL333, 57 NTC_NCP15XH103, 58 NTC_NCP18WB473, 59 NTC_NCP21WB473, 60 NTC_LAST, 61 }; 62 63 static const struct platform_device_id ntc_thermistor_id[] = { 64 [NTC_B57330V2103] = { "b57330v2103", TYPE_B57330V2103 }, 65 [NTC_B57891S0103] = { "b57891s0103", TYPE_B57891S0103 }, 66 [NTC_NCP03WB473] = { "ncp03wb473", TYPE_NCPXXWB473 }, 67 [NTC_NCP03WF104] = { "ncp03wf104", TYPE_NCPXXWF104 }, 68 [NTC_NCP15WB473] = { "ncp15wb473", TYPE_NCPXXWB473 }, 69 [NTC_NCP15WL333] = { "ncp15wl333", TYPE_NCPXXWL333 }, 70 [NTC_NCP15XH103] = { "ncp15xh103", TYPE_NCPXXXH103 }, 71 [NTC_NCP18WB473] = { "ncp18wb473", TYPE_NCPXXWB473 }, 72 [NTC_NCP21WB473] = { "ncp21wb473", TYPE_NCPXXWB473 }, 73 [NTC_LAST] = { }, 74 }; 75 76 /* 77 * A compensation table should be sorted by the values of .ohm 78 * in descending order. 79 * The following compensation tables are from the specification of Murata NTC 80 * Thermistors Datasheet 81 */ 82 static const struct ntc_compensation ncpXXwb473[] = { 83 { .temp_c = -40, .ohm = 1747920 }, 84 { .temp_c = -35, .ohm = 1245428 }, 85 { .temp_c = -30, .ohm = 898485 }, 86 { .temp_c = -25, .ohm = 655802 }, 87 { .temp_c = -20, .ohm = 483954 }, 88 { .temp_c = -15, .ohm = 360850 }, 89 { .temp_c = -10, .ohm = 271697 }, 90 { .temp_c = -5, .ohm = 206463 }, 91 { .temp_c = 0, .ohm = 158214 }, 92 { .temp_c = 5, .ohm = 122259 }, 93 { .temp_c = 10, .ohm = 95227 }, 94 { .temp_c = 15, .ohm = 74730 }, 95 { .temp_c = 20, .ohm = 59065 }, 96 { .temp_c = 25, .ohm = 47000 }, 97 { .temp_c = 30, .ohm = 37643 }, 98 { .temp_c = 35, .ohm = 30334 }, 99 { .temp_c = 40, .ohm = 24591 }, 100 { .temp_c = 45, .ohm = 20048 }, 101 { .temp_c = 50, .ohm = 16433 }, 102 { .temp_c = 55, .ohm = 13539 }, 103 { .temp_c = 60, .ohm = 11209 }, 104 { .temp_c = 65, .ohm = 9328 }, 105 { .temp_c = 70, .ohm = 7798 }, 106 { .temp_c = 75, .ohm = 6544 }, 107 { .temp_c = 80, .ohm = 5518 }, 108 { .temp_c = 85, .ohm = 4674 }, 109 { .temp_c = 90, .ohm = 3972 }, 110 { .temp_c = 95, .ohm = 3388 }, 111 { .temp_c = 100, .ohm = 2902 }, 112 { .temp_c = 105, .ohm = 2494 }, 113 { .temp_c = 110, .ohm = 2150 }, 114 { .temp_c = 115, .ohm = 1860 }, 115 { .temp_c = 120, .ohm = 1615 }, 116 { .temp_c = 125, .ohm = 1406 }, 117 }; 118 static const struct ntc_compensation ncpXXwl333[] = { 119 { .temp_c = -40, .ohm = 1610154 }, 120 { .temp_c = -35, .ohm = 1130850 }, 121 { .temp_c = -30, .ohm = 802609 }, 122 { .temp_c = -25, .ohm = 575385 }, 123 { .temp_c = -20, .ohm = 416464 }, 124 { .temp_c = -15, .ohm = 304219 }, 125 { .temp_c = -10, .ohm = 224193 }, 126 { .temp_c = -5, .ohm = 166623 }, 127 { .temp_c = 0, .ohm = 124850 }, 128 { .temp_c = 5, .ohm = 94287 }, 129 { .temp_c = 10, .ohm = 71747 }, 130 { .temp_c = 15, .ohm = 54996 }, 131 { .temp_c = 20, .ohm = 42455 }, 132 { .temp_c = 25, .ohm = 33000 }, 133 { .temp_c = 30, .ohm = 25822 }, 134 { .temp_c = 35, .ohm = 20335 }, 135 { .temp_c = 40, .ohm = 16115 }, 136 { .temp_c = 45, .ohm = 12849 }, 137 { .temp_c = 50, .ohm = 10306 }, 138 { .temp_c = 55, .ohm = 8314 }, 139 { .temp_c = 60, .ohm = 6746 }, 140 { .temp_c = 65, .ohm = 5503 }, 141 { .temp_c = 70, .ohm = 4513 }, 142 { .temp_c = 75, .ohm = 3721 }, 143 { .temp_c = 80, .ohm = 3084 }, 144 { .temp_c = 85, .ohm = 2569 }, 145 { .temp_c = 90, .ohm = 2151 }, 146 { .temp_c = 95, .ohm = 1809 }, 147 { .temp_c = 100, .ohm = 1529 }, 148 { .temp_c = 105, .ohm = 1299 }, 149 { .temp_c = 110, .ohm = 1108 }, 150 { .temp_c = 115, .ohm = 949 }, 151 { .temp_c = 120, .ohm = 817 }, 152 { .temp_c = 125, .ohm = 707 }, 153 }; 154 155 static const struct ntc_compensation ncpXXwf104[] = { 156 { .temp_c = -40, .ohm = 4397119 }, 157 { .temp_c = -35, .ohm = 3088599 }, 158 { .temp_c = -30, .ohm = 2197225 }, 159 { .temp_c = -25, .ohm = 1581881 }, 160 { .temp_c = -20, .ohm = 1151037 }, 161 { .temp_c = -15, .ohm = 846579 }, 162 { .temp_c = -10, .ohm = 628988 }, 163 { .temp_c = -5, .ohm = 471632 }, 164 { .temp_c = 0, .ohm = 357012 }, 165 { .temp_c = 5, .ohm = 272500 }, 166 { .temp_c = 10, .ohm = 209710 }, 167 { .temp_c = 15, .ohm = 162651 }, 168 { .temp_c = 20, .ohm = 127080 }, 169 { .temp_c = 25, .ohm = 100000 }, 170 { .temp_c = 30, .ohm = 79222 }, 171 { .temp_c = 35, .ohm = 63167 }, 172 { .temp_c = 40, .ohm = 50677 }, 173 { .temp_c = 45, .ohm = 40904 }, 174 { .temp_c = 50, .ohm = 33195 }, 175 { .temp_c = 55, .ohm = 27091 }, 176 { .temp_c = 60, .ohm = 22224 }, 177 { .temp_c = 65, .ohm = 18323 }, 178 { .temp_c = 70, .ohm = 15184 }, 179 { .temp_c = 75, .ohm = 12635 }, 180 { .temp_c = 80, .ohm = 10566 }, 181 { .temp_c = 85, .ohm = 8873 }, 182 { .temp_c = 90, .ohm = 7481 }, 183 { .temp_c = 95, .ohm = 6337 }, 184 { .temp_c = 100, .ohm = 5384 }, 185 { .temp_c = 105, .ohm = 4594 }, 186 { .temp_c = 110, .ohm = 3934 }, 187 { .temp_c = 115, .ohm = 3380 }, 188 { .temp_c = 120, .ohm = 2916 }, 189 { .temp_c = 125, .ohm = 2522 }, 190 }; 191 192 static const struct ntc_compensation ncpXXxh103[] = { 193 { .temp_c = -40, .ohm = 247565 }, 194 { .temp_c = -35, .ohm = 181742 }, 195 { .temp_c = -30, .ohm = 135128 }, 196 { .temp_c = -25, .ohm = 101678 }, 197 { .temp_c = -20, .ohm = 77373 }, 198 { .temp_c = -15, .ohm = 59504 }, 199 { .temp_c = -10, .ohm = 46222 }, 200 { .temp_c = -5, .ohm = 36244 }, 201 { .temp_c = 0, .ohm = 28674 }, 202 { .temp_c = 5, .ohm = 22878 }, 203 { .temp_c = 10, .ohm = 18399 }, 204 { .temp_c = 15, .ohm = 14910 }, 205 { .temp_c = 20, .ohm = 12169 }, 206 { .temp_c = 25, .ohm = 10000 }, 207 { .temp_c = 30, .ohm = 8271 }, 208 { .temp_c = 35, .ohm = 6883 }, 209 { .temp_c = 40, .ohm = 5762 }, 210 { .temp_c = 45, .ohm = 4851 }, 211 { .temp_c = 50, .ohm = 4105 }, 212 { .temp_c = 55, .ohm = 3492 }, 213 { .temp_c = 60, .ohm = 2985 }, 214 { .temp_c = 65, .ohm = 2563 }, 215 { .temp_c = 70, .ohm = 2211 }, 216 { .temp_c = 75, .ohm = 1915 }, 217 { .temp_c = 80, .ohm = 1666 }, 218 { .temp_c = 85, .ohm = 1454 }, 219 { .temp_c = 90, .ohm = 1275 }, 220 { .temp_c = 95, .ohm = 1121 }, 221 { .temp_c = 100, .ohm = 990 }, 222 { .temp_c = 105, .ohm = 876 }, 223 { .temp_c = 110, .ohm = 779 }, 224 { .temp_c = 115, .ohm = 694 }, 225 { .temp_c = 120, .ohm = 620 }, 226 { .temp_c = 125, .ohm = 556 }, 227 }; 228 229 /* 230 * The following compensation tables are from the specifications in EPCOS NTC 231 * Thermistors Datasheets 232 */ 233 static const struct ntc_compensation b57330v2103[] = { 234 { .temp_c = -40, .ohm = 190030 }, 235 { .temp_c = -35, .ohm = 145360 }, 236 { .temp_c = -30, .ohm = 112060 }, 237 { .temp_c = -25, .ohm = 87041 }, 238 { .temp_c = -20, .ohm = 68104 }, 239 { .temp_c = -15, .ohm = 53665 }, 240 { .temp_c = -10, .ohm = 42576 }, 241 { .temp_c = -5, .ohm = 34001 }, 242 { .temp_c = 0, .ohm = 27326 }, 243 { .temp_c = 5, .ohm = 22096 }, 244 { .temp_c = 10, .ohm = 17973 }, 245 { .temp_c = 15, .ohm = 14703 }, 246 { .temp_c = 20, .ohm = 12090 }, 247 { .temp_c = 25, .ohm = 10000 }, 248 { .temp_c = 30, .ohm = 8311 }, 249 { .temp_c = 35, .ohm = 6941 }, 250 { .temp_c = 40, .ohm = 5825 }, 251 { .temp_c = 45, .ohm = 4911 }, 252 { .temp_c = 50, .ohm = 4158 }, 253 { .temp_c = 55, .ohm = 3536 }, 254 { .temp_c = 60, .ohm = 3019 }, 255 { .temp_c = 65, .ohm = 2588 }, 256 { .temp_c = 70, .ohm = 2227 }, 257 { .temp_c = 75, .ohm = 1924 }, 258 { .temp_c = 80, .ohm = 1668 }, 259 { .temp_c = 85, .ohm = 1451 }, 260 { .temp_c = 90, .ohm = 1266 }, 261 { .temp_c = 95, .ohm = 1108 }, 262 { .temp_c = 100, .ohm = 973 }, 263 { .temp_c = 105, .ohm = 857 }, 264 { .temp_c = 110, .ohm = 757 }, 265 { .temp_c = 115, .ohm = 671 }, 266 { .temp_c = 120, .ohm = 596 }, 267 { .temp_c = 125, .ohm = 531 }, 268 }; 269 270 static const struct ntc_compensation b57891s0103[] = { 271 { .temp_c = -55.0, .ohm = 878900 }, 272 { .temp_c = -50.0, .ohm = 617590 }, 273 { .temp_c = -45.0, .ohm = 439340 }, 274 { .temp_c = -40.0, .ohm = 316180 }, 275 { .temp_c = -35.0, .ohm = 230060 }, 276 { .temp_c = -30.0, .ohm = 169150 }, 277 { .temp_c = -25.0, .ohm = 125550 }, 278 { .temp_c = -20.0, .ohm = 94143 }, 279 { .temp_c = -15.0, .ohm = 71172 }, 280 { .temp_c = -10.0, .ohm = 54308 }, 281 { .temp_c = -5.0, .ohm = 41505 }, 282 { .temp_c = 0.0, .ohm = 32014 }, 283 { .temp_c = 5.0, .ohm = 25011 }, 284 { .temp_c = 10.0, .ohm = 19691 }, 285 { .temp_c = 15.0, .ohm = 15618 }, 286 { .temp_c = 20.0, .ohm = 12474 }, 287 { .temp_c = 25.0, .ohm = 10000 }, 288 { .temp_c = 30.0, .ohm = 8080 }, 289 { .temp_c = 35.0, .ohm = 6569 }, 290 { .temp_c = 40.0, .ohm = 5372 }, 291 { .temp_c = 45.0, .ohm = 4424 }, 292 { .temp_c = 50.0, .ohm = 3661 }, 293 { .temp_c = 55.0, .ohm = 3039 }, 294 { .temp_c = 60.0, .ohm = 2536 }, 295 { .temp_c = 65.0, .ohm = 2128 }, 296 { .temp_c = 70.0, .ohm = 1794 }, 297 { .temp_c = 75.0, .ohm = 1518 }, 298 { .temp_c = 80.0, .ohm = 1290 }, 299 { .temp_c = 85.0, .ohm = 1100 }, 300 { .temp_c = 90.0, .ohm = 942 }, 301 { .temp_c = 95.0, .ohm = 809 }, 302 { .temp_c = 100.0, .ohm = 697 }, 303 { .temp_c = 105.0, .ohm = 604 }, 304 { .temp_c = 110.0, .ohm = 525 }, 305 { .temp_c = 115.0, .ohm = 457 }, 306 { .temp_c = 120.0, .ohm = 400 }, 307 { .temp_c = 125.0, .ohm = 351 }, 308 { .temp_c = 130.0, .ohm = 308 }, 309 { .temp_c = 135.0, .ohm = 272 }, 310 { .temp_c = 140.0, .ohm = 240 }, 311 { .temp_c = 145.0, .ohm = 213 }, 312 { .temp_c = 150.0, .ohm = 189 }, 313 { .temp_c = 155.0, .ohm = 168 }, 314 }; 315 316 struct ntc_type { 317 const struct ntc_compensation *comp; 318 int n_comp; 319 }; 320 321 #define NTC_TYPE(ntc, compensation) \ 322 [(ntc)] = { .comp = (compensation), .n_comp = ARRAY_SIZE(compensation) } 323 324 static const struct ntc_type ntc_type[] = { 325 NTC_TYPE(TYPE_B57330V2103, b57330v2103), 326 NTC_TYPE(TYPE_B57891S0103, b57891s0103), 327 NTC_TYPE(TYPE_NCPXXWB473, ncpXXwb473), 328 NTC_TYPE(TYPE_NCPXXWF104, ncpXXwf104), 329 NTC_TYPE(TYPE_NCPXXWL333, ncpXXwl333), 330 NTC_TYPE(TYPE_NCPXXXH103, ncpXXxh103), 331 }; 332 333 struct ntc_data { 334 struct ntc_thermistor_platform_data *pdata; 335 const struct ntc_compensation *comp; 336 int n_comp; 337 }; 338 339 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO) 340 static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata) 341 { 342 struct iio_channel *channel = pdata->chan; 343 int raw, uv, ret; 344 345 ret = iio_read_channel_raw(channel, &raw); 346 if (ret < 0) { 347 pr_err("read channel() error: %d\n", ret); 348 return ret; 349 } 350 351 ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000); 352 if (ret < 0) { 353 /* Assume 12 bit ADC with vref at pullup_uv */ 354 uv = (pdata->pullup_uv * (s64)raw) >> 12; 355 } 356 357 return uv; 358 } 359 360 static const struct of_device_id ntc_match[] = { 361 { .compatible = "epcos,b57330v2103", 362 .data = &ntc_thermistor_id[NTC_B57330V2103]}, 363 { .compatible = "epcos,b57891s0103", 364 .data = &ntc_thermistor_id[NTC_B57891S0103] }, 365 { .compatible = "murata,ncp03wb473", 366 .data = &ntc_thermistor_id[NTC_NCP03WB473] }, 367 { .compatible = "murata,ncp03wf104", 368 .data = &ntc_thermistor_id[NTC_NCP03WF104] }, 369 { .compatible = "murata,ncp15wb473", 370 .data = &ntc_thermistor_id[NTC_NCP15WB473] }, 371 { .compatible = "murata,ncp15wl333", 372 .data = &ntc_thermistor_id[NTC_NCP15WL333] }, 373 { .compatible = "murata,ncp15xh103", 374 .data = &ntc_thermistor_id[NTC_NCP15XH103] }, 375 { .compatible = "murata,ncp18wb473", 376 .data = &ntc_thermistor_id[NTC_NCP18WB473] }, 377 { .compatible = "murata,ncp21wb473", 378 .data = &ntc_thermistor_id[NTC_NCP21WB473] }, 379 380 /* Usage of vendor name "ntc" is deprecated */ 381 { .compatible = "ntc,ncp03wb473", 382 .data = &ntc_thermistor_id[NTC_NCP03WB473] }, 383 { .compatible = "ntc,ncp15wb473", 384 .data = &ntc_thermistor_id[NTC_NCP15WB473] }, 385 { .compatible = "ntc,ncp15wl333", 386 .data = &ntc_thermistor_id[NTC_NCP15WL333] }, 387 { .compatible = "ntc,ncp18wb473", 388 .data = &ntc_thermistor_id[NTC_NCP18WB473] }, 389 { .compatible = "ntc,ncp21wb473", 390 .data = &ntc_thermistor_id[NTC_NCP21WB473] }, 391 { }, 392 }; 393 MODULE_DEVICE_TABLE(of, ntc_match); 394 395 static struct ntc_thermistor_platform_data * 396 ntc_thermistor_parse_dt(struct device *dev) 397 { 398 struct iio_channel *chan; 399 enum iio_chan_type type; 400 struct device_node *np = dev->of_node; 401 struct ntc_thermistor_platform_data *pdata; 402 int ret; 403 404 if (!np) 405 return NULL; 406 407 pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL); 408 if (!pdata) 409 return ERR_PTR(-ENOMEM); 410 411 chan = devm_iio_channel_get(dev, NULL); 412 if (IS_ERR(chan)) 413 return ERR_CAST(chan); 414 415 ret = iio_get_channel_type(chan, &type); 416 if (ret < 0) 417 return ERR_PTR(ret); 418 419 if (type != IIO_VOLTAGE) 420 return ERR_PTR(-EINVAL); 421 422 if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv)) 423 return ERR_PTR(-ENODEV); 424 if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm)) 425 return ERR_PTR(-ENODEV); 426 if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm)) 427 return ERR_PTR(-ENODEV); 428 429 if (of_find_property(np, "connected-positive", NULL)) 430 pdata->connect = NTC_CONNECTED_POSITIVE; 431 else /* status change should be possible if not always on. */ 432 pdata->connect = NTC_CONNECTED_GROUND; 433 434 pdata->chan = chan; 435 pdata->read_uv = ntc_adc_iio_read; 436 437 return pdata; 438 } 439 #else 440 static struct ntc_thermistor_platform_data * 441 ntc_thermistor_parse_dt(struct device *dev) 442 { 443 return NULL; 444 } 445 446 #define ntc_match NULL 447 448 #endif 449 450 static inline u64 div64_u64_safe(u64 dividend, u64 divisor) 451 { 452 if (divisor == 0 && dividend == 0) 453 return 0; 454 if (divisor == 0) 455 return UINT_MAX; 456 return div64_u64(dividend, divisor); 457 } 458 459 static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv) 460 { 461 struct ntc_thermistor_platform_data *pdata = data->pdata; 462 u32 puv = pdata->pullup_uv; 463 u64 n, puo, pdo; 464 puo = pdata->pullup_ohm; 465 pdo = pdata->pulldown_ohm; 466 467 if (uv == 0) 468 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 469 INT_MAX : 0; 470 if (uv >= puv) 471 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 472 0 : INT_MAX; 473 474 if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0) 475 n = div_u64(pdo * (puv - uv), uv); 476 else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0) 477 n = div_u64(puo * uv, puv - uv); 478 else if (pdata->connect == NTC_CONNECTED_POSITIVE) 479 n = div64_u64_safe(pdo * puo * (puv - uv), 480 puo * uv - pdo * (puv - uv)); 481 else 482 n = div64_u64_safe(pdo * puo * uv, pdo * (puv - uv) - puo * uv); 483 484 if (n > INT_MAX) 485 n = INT_MAX; 486 return n; 487 } 488 489 static void lookup_comp(struct ntc_data *data, unsigned int ohm, 490 int *i_low, int *i_high) 491 { 492 int start, end, mid; 493 494 /* 495 * Handle special cases: Resistance is higher than or equal to 496 * resistance in first table entry, or resistance is lower or equal 497 * to resistance in last table entry. 498 * In these cases, return i_low == i_high, either pointing to the 499 * beginning or to the end of the table depending on the condition. 500 */ 501 if (ohm >= data->comp[0].ohm) { 502 *i_low = 0; 503 *i_high = 0; 504 return; 505 } 506 if (ohm <= data->comp[data->n_comp - 1].ohm) { 507 *i_low = data->n_comp - 1; 508 *i_high = data->n_comp - 1; 509 return; 510 } 511 512 /* Do a binary search on compensation table */ 513 start = 0; 514 end = data->n_comp; 515 while (start < end) { 516 mid = start + (end - start) / 2; 517 /* 518 * start <= mid < end 519 * data->comp[start].ohm > ohm >= data->comp[end].ohm 520 * 521 * We could check for "ohm == data->comp[mid].ohm" here, but 522 * that is a quite unlikely condition, and we would have to 523 * check again after updating start. Check it at the end instead 524 * for simplicity. 525 */ 526 if (ohm >= data->comp[mid].ohm) { 527 end = mid; 528 } else { 529 start = mid + 1; 530 /* 531 * ohm >= data->comp[start].ohm might be true here, 532 * since we set start to mid + 1. In that case, we are 533 * done. We could keep going, but the condition is quite 534 * likely to occur, so it is worth checking for it. 535 */ 536 if (ohm >= data->comp[start].ohm) 537 end = start; 538 } 539 /* 540 * start <= end 541 * data->comp[start].ohm >= ohm >= data->comp[end].ohm 542 */ 543 } 544 /* 545 * start == end 546 * ohm >= data->comp[end].ohm 547 */ 548 *i_low = end; 549 if (ohm == data->comp[end].ohm) 550 *i_high = end; 551 else 552 *i_high = end - 1; 553 } 554 555 static int get_temp_mc(struct ntc_data *data, unsigned int ohm) 556 { 557 int low, high; 558 int temp; 559 560 lookup_comp(data, ohm, &low, &high); 561 if (low == high) { 562 /* Unable to use linear approximation */ 563 temp = data->comp[low].temp_c * 1000; 564 } else { 565 temp = data->comp[low].temp_c * 1000 + 566 ((data->comp[high].temp_c - data->comp[low].temp_c) * 567 1000 * ((int)ohm - (int)data->comp[low].ohm)) / 568 ((int)data->comp[high].ohm - (int)data->comp[low].ohm); 569 } 570 return temp; 571 } 572 573 static int ntc_thermistor_get_ohm(struct ntc_data *data) 574 { 575 int read_uv; 576 577 if (data->pdata->read_ohm) 578 return data->pdata->read_ohm(); 579 580 if (data->pdata->read_uv) { 581 read_uv = data->pdata->read_uv(data->pdata); 582 if (read_uv < 0) 583 return read_uv; 584 return get_ohm_of_thermistor(data, read_uv); 585 } 586 return -EINVAL; 587 } 588 589 static int ntc_read(struct device *dev, enum hwmon_sensor_types type, 590 u32 attr, int channel, long *val) 591 { 592 struct ntc_data *data = dev_get_drvdata(dev); 593 int ohm; 594 595 switch (type) { 596 case hwmon_temp: 597 switch (attr) { 598 case hwmon_temp_input: 599 ohm = ntc_thermistor_get_ohm(data); 600 if (ohm < 0) 601 return ohm; 602 *val = get_temp_mc(data, ohm); 603 return 0; 604 case hwmon_temp_type: 605 *val = 4; 606 return 0; 607 default: 608 break; 609 } 610 break; 611 default: 612 break; 613 } 614 return -EINVAL; 615 } 616 617 static umode_t ntc_is_visible(const void *data, enum hwmon_sensor_types type, 618 u32 attr, int channel) 619 { 620 if (type == hwmon_temp) { 621 switch (attr) { 622 case hwmon_temp_input: 623 case hwmon_temp_type: 624 return 0444; 625 default: 626 break; 627 } 628 } 629 return 0; 630 } 631 632 static const u32 ntc_chip_config[] = { 633 HWMON_C_REGISTER_TZ, 634 0 635 }; 636 637 static const struct hwmon_channel_info ntc_chip = { 638 .type = hwmon_chip, 639 .config = ntc_chip_config, 640 }; 641 642 static const u32 ntc_temp_config[] = { 643 HWMON_T_INPUT, HWMON_T_TYPE, 644 0 645 }; 646 647 static const struct hwmon_channel_info ntc_temp = { 648 .type = hwmon_temp, 649 .config = ntc_temp_config, 650 }; 651 652 static const struct hwmon_channel_info *ntc_info[] = { 653 &ntc_chip, 654 &ntc_temp, 655 NULL 656 }; 657 658 static const struct hwmon_ops ntc_hwmon_ops = { 659 .is_visible = ntc_is_visible, 660 .read = ntc_read, 661 }; 662 663 static const struct hwmon_chip_info ntc_chip_info = { 664 .ops = &ntc_hwmon_ops, 665 .info = ntc_info, 666 }; 667 668 static int ntc_thermistor_probe(struct platform_device *pdev) 669 { 670 struct device *dev = &pdev->dev; 671 const struct of_device_id *of_id = 672 of_match_device(of_match_ptr(ntc_match), dev); 673 const struct platform_device_id *pdev_id; 674 struct ntc_thermistor_platform_data *pdata; 675 struct device *hwmon_dev; 676 struct ntc_data *data; 677 678 pdata = ntc_thermistor_parse_dt(dev); 679 if (IS_ERR(pdata)) 680 return PTR_ERR(pdata); 681 else if (pdata == NULL) 682 pdata = dev_get_platdata(dev); 683 684 if (!pdata) { 685 dev_err(dev, "No platform init data supplied.\n"); 686 return -ENODEV; 687 } 688 689 /* Either one of the two is required. */ 690 if (!pdata->read_uv && !pdata->read_ohm) { 691 dev_err(dev, 692 "Both read_uv and read_ohm missing. Need either one of the two.\n"); 693 return -EINVAL; 694 } 695 696 if (pdata->read_uv && pdata->read_ohm) { 697 dev_warn(dev, 698 "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n"); 699 pdata->read_uv = NULL; 700 } 701 702 if (pdata->read_uv && (pdata->pullup_uv == 0 || 703 (pdata->pullup_ohm == 0 && pdata->connect == 704 NTC_CONNECTED_GROUND) || 705 (pdata->pulldown_ohm == 0 && pdata->connect == 706 NTC_CONNECTED_POSITIVE) || 707 (pdata->connect != NTC_CONNECTED_POSITIVE && 708 pdata->connect != NTC_CONNECTED_GROUND))) { 709 dev_err(dev, "Required data to use read_uv not supplied.\n"); 710 return -EINVAL; 711 } 712 713 data = devm_kzalloc(dev, sizeof(struct ntc_data), GFP_KERNEL); 714 if (!data) 715 return -ENOMEM; 716 717 pdev_id = of_id ? of_id->data : platform_get_device_id(pdev); 718 719 data->pdata = pdata; 720 721 if (pdev_id->driver_data >= ARRAY_SIZE(ntc_type)) { 722 dev_err(dev, "Unknown device type: %lu(%s)\n", 723 pdev_id->driver_data, pdev_id->name); 724 return -EINVAL; 725 } 726 727 data->comp = ntc_type[pdev_id->driver_data].comp; 728 data->n_comp = ntc_type[pdev_id->driver_data].n_comp; 729 730 hwmon_dev = devm_hwmon_device_register_with_info(dev, pdev_id->name, 731 data, &ntc_chip_info, 732 NULL); 733 if (IS_ERR(hwmon_dev)) { 734 dev_err(dev, "unable to register as hwmon device.\n"); 735 return PTR_ERR(hwmon_dev); 736 } 737 738 dev_info(dev, "Thermistor type: %s successfully probed.\n", 739 pdev_id->name); 740 741 return 0; 742 } 743 744 static struct platform_driver ntc_thermistor_driver = { 745 .driver = { 746 .name = "ntc-thermistor", 747 .of_match_table = of_match_ptr(ntc_match), 748 }, 749 .probe = ntc_thermistor_probe, 750 .id_table = ntc_thermistor_id, 751 }; 752 753 module_platform_driver(ntc_thermistor_driver); 754 755 MODULE_DESCRIPTION("NTC Thermistor Driver"); 756 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 757 MODULE_LICENSE("GPL"); 758 MODULE_ALIAS("platform:ntc-thermistor"); 759