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 30 #include <linux/platform_data/ntc_thermistor.h> 31 32 #include <linux/hwmon.h> 33 #include <linux/hwmon-sysfs.h> 34 35 struct ntc_compensation { 36 int temp_C; 37 unsigned int ohm; 38 }; 39 40 /* 41 * A compensation table should be sorted by the values of .ohm 42 * in descending order. 43 * The following compensation tables are from the specification of Murata NTC 44 * Thermistors Datasheet 45 */ 46 const struct ntc_compensation ncpXXwb473[] = { 47 { .temp_C = -40, .ohm = 1747920 }, 48 { .temp_C = -35, .ohm = 1245428 }, 49 { .temp_C = -30, .ohm = 898485 }, 50 { .temp_C = -25, .ohm = 655802 }, 51 { .temp_C = -20, .ohm = 483954 }, 52 { .temp_C = -15, .ohm = 360850 }, 53 { .temp_C = -10, .ohm = 271697 }, 54 { .temp_C = -5, .ohm = 206463 }, 55 { .temp_C = 0, .ohm = 158214 }, 56 { .temp_C = 5, .ohm = 122259 }, 57 { .temp_C = 10, .ohm = 95227 }, 58 { .temp_C = 15, .ohm = 74730 }, 59 { .temp_C = 20, .ohm = 59065 }, 60 { .temp_C = 25, .ohm = 47000 }, 61 { .temp_C = 30, .ohm = 37643 }, 62 { .temp_C = 35, .ohm = 30334 }, 63 { .temp_C = 40, .ohm = 24591 }, 64 { .temp_C = 45, .ohm = 20048 }, 65 { .temp_C = 50, .ohm = 16433 }, 66 { .temp_C = 55, .ohm = 13539 }, 67 { .temp_C = 60, .ohm = 11209 }, 68 { .temp_C = 65, .ohm = 9328 }, 69 { .temp_C = 70, .ohm = 7798 }, 70 { .temp_C = 75, .ohm = 6544 }, 71 { .temp_C = 80, .ohm = 5518 }, 72 { .temp_C = 85, .ohm = 4674 }, 73 { .temp_C = 90, .ohm = 3972 }, 74 { .temp_C = 95, .ohm = 3388 }, 75 { .temp_C = 100, .ohm = 2902 }, 76 { .temp_C = 105, .ohm = 2494 }, 77 { .temp_C = 110, .ohm = 2150 }, 78 { .temp_C = 115, .ohm = 1860 }, 79 { .temp_C = 120, .ohm = 1615 }, 80 { .temp_C = 125, .ohm = 1406 }, 81 }; 82 const struct ntc_compensation ncpXXwl333[] = { 83 { .temp_C = -40, .ohm = 1610154 }, 84 { .temp_C = -35, .ohm = 1130850 }, 85 { .temp_C = -30, .ohm = 802609 }, 86 { .temp_C = -25, .ohm = 575385 }, 87 { .temp_C = -20, .ohm = 416464 }, 88 { .temp_C = -15, .ohm = 304219 }, 89 { .temp_C = -10, .ohm = 224193 }, 90 { .temp_C = -5, .ohm = 166623 }, 91 { .temp_C = 0, .ohm = 124850 }, 92 { .temp_C = 5, .ohm = 94287 }, 93 { .temp_C = 10, .ohm = 71747 }, 94 { .temp_C = 15, .ohm = 54996 }, 95 { .temp_C = 20, .ohm = 42455 }, 96 { .temp_C = 25, .ohm = 33000 }, 97 { .temp_C = 30, .ohm = 25822 }, 98 { .temp_C = 35, .ohm = 20335 }, 99 { .temp_C = 40, .ohm = 16115 }, 100 { .temp_C = 45, .ohm = 12849 }, 101 { .temp_C = 50, .ohm = 10306 }, 102 { .temp_C = 55, .ohm = 8314 }, 103 { .temp_C = 60, .ohm = 6746 }, 104 { .temp_C = 65, .ohm = 5503 }, 105 { .temp_C = 70, .ohm = 4513 }, 106 { .temp_C = 75, .ohm = 3721 }, 107 { .temp_C = 80, .ohm = 3084 }, 108 { .temp_C = 85, .ohm = 2569 }, 109 { .temp_C = 90, .ohm = 2151 }, 110 { .temp_C = 95, .ohm = 1809 }, 111 { .temp_C = 100, .ohm = 1529 }, 112 { .temp_C = 105, .ohm = 1299 }, 113 { .temp_C = 110, .ohm = 1108 }, 114 { .temp_C = 115, .ohm = 949 }, 115 { .temp_C = 120, .ohm = 817 }, 116 { .temp_C = 125, .ohm = 707 }, 117 }; 118 119 struct ntc_data { 120 struct device *hwmon_dev; 121 struct ntc_thermistor_platform_data *pdata; 122 const struct ntc_compensation *comp; 123 struct device *dev; 124 int n_comp; 125 char name[PLATFORM_NAME_SIZE]; 126 }; 127 128 static inline u64 div64_u64_safe(u64 dividend, u64 divisor) 129 { 130 if (divisor == 0 && dividend == 0) 131 return 0; 132 if (divisor == 0) 133 return UINT_MAX; 134 return div64_u64(dividend, divisor); 135 } 136 137 static unsigned int get_ohm_of_thermistor(struct ntc_data *data, 138 unsigned int uV) 139 { 140 struct ntc_thermistor_platform_data *pdata = data->pdata; 141 u64 mV = uV / 1000; 142 u64 pmV = pdata->pullup_uV / 1000; 143 u64 N, puO, pdO; 144 puO = pdata->pullup_ohm; 145 pdO = pdata->pulldown_ohm; 146 147 if (mV == 0) { 148 if (pdata->connect == NTC_CONNECTED_POSITIVE) 149 return UINT_MAX; 150 return 0; 151 } 152 if (mV >= pmV) 153 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 154 0 : UINT_MAX; 155 156 if (pdata->connect == NTC_CONNECTED_POSITIVE && puO == 0) 157 N = div64_u64_safe(pdO * (pmV - mV), mV); 158 else if (pdata->connect == NTC_CONNECTED_GROUND && pdO == 0) 159 N = div64_u64_safe(puO * mV, pmV - mV); 160 else if (pdata->connect == NTC_CONNECTED_POSITIVE) 161 N = div64_u64_safe(pdO * puO * (pmV - mV), 162 puO * mV - pdO * (pmV - mV)); 163 else 164 N = div64_u64_safe(pdO * puO * mV, pdO * (pmV - mV) - puO * mV); 165 166 return (unsigned int) N; 167 } 168 169 static int lookup_comp(struct ntc_data *data, 170 unsigned int ohm, int *i_low, int *i_high) 171 { 172 int start, end, mid = -1; 173 174 /* Do a binary search on compensation table */ 175 start = 0; 176 end = data->n_comp; 177 178 while (end > start) { 179 mid = start + (end - start) / 2; 180 if (data->comp[mid].ohm < ohm) 181 end = mid; 182 else if (data->comp[mid].ohm > ohm) 183 start = mid + 1; 184 else 185 break; 186 } 187 188 if (mid == 0) { 189 if (data->comp[mid].ohm > ohm) { 190 *i_high = mid; 191 *i_low = mid + 1; 192 return 0; 193 } else { 194 *i_low = mid; 195 *i_high = -1; 196 return -EINVAL; 197 } 198 } 199 if (mid == (data->n_comp - 1)) { 200 if (data->comp[mid].ohm <= ohm) { 201 *i_low = mid; 202 *i_high = mid - 1; 203 return 0; 204 } else { 205 *i_low = -1; 206 *i_high = mid; 207 return -EINVAL; 208 } 209 } 210 211 if (data->comp[mid].ohm <= ohm) { 212 *i_low = mid; 213 *i_high = mid - 1; 214 } 215 if (data->comp[mid].ohm > ohm) { 216 *i_low = mid + 1; 217 *i_high = mid; 218 } 219 220 return 0; 221 } 222 223 static int get_temp_mC(struct ntc_data *data, unsigned int ohm, int *temp) 224 { 225 int low, high; 226 int ret; 227 228 ret = lookup_comp(data, ohm, &low, &high); 229 if (ret) { 230 /* Unable to use linear approximation */ 231 if (low != -1) 232 *temp = data->comp[low].temp_C * 1000; 233 else if (high != -1) 234 *temp = data->comp[high].temp_C * 1000; 235 else 236 return ret; 237 } else { 238 *temp = data->comp[low].temp_C * 1000 + 239 ((data->comp[high].temp_C - data->comp[low].temp_C) * 240 1000 * ((int)ohm - (int)data->comp[low].ohm)) / 241 ((int)data->comp[high].ohm - (int)data->comp[low].ohm); 242 } 243 244 return 0; 245 } 246 247 static int ntc_thermistor_read(struct ntc_data *data, int *temp) 248 { 249 int ret; 250 int read_ohm, read_uV; 251 unsigned int ohm = 0; 252 253 if (data->pdata->read_ohm) { 254 read_ohm = data->pdata->read_ohm(); 255 if (read_ohm < 0) 256 return read_ohm; 257 ohm = (unsigned int)read_ohm; 258 } 259 260 if (data->pdata->read_uV) { 261 read_uV = data->pdata->read_uV(); 262 if (read_uV < 0) 263 return read_uV; 264 ohm = get_ohm_of_thermistor(data, (unsigned int)read_uV); 265 } 266 267 ret = get_temp_mC(data, ohm, temp); 268 if (ret) { 269 dev_dbg(data->dev, "Sensor reading function not available.\n"); 270 return ret; 271 } 272 273 return 0; 274 } 275 276 static ssize_t ntc_show_name(struct device *dev, 277 struct device_attribute *attr, char *buf) 278 { 279 struct ntc_data *data = dev_get_drvdata(dev); 280 281 return sprintf(buf, "%s\n", data->name); 282 } 283 284 static ssize_t ntc_show_type(struct device *dev, 285 struct device_attribute *attr, char *buf) 286 { 287 return sprintf(buf, "4\n"); 288 } 289 290 static ssize_t ntc_show_temp(struct device *dev, 291 struct device_attribute *attr, char *buf) 292 { 293 struct ntc_data *data = dev_get_drvdata(dev); 294 int temp, ret; 295 296 ret = ntc_thermistor_read(data, &temp); 297 if (ret) 298 return ret; 299 return sprintf(buf, "%d\n", temp); 300 } 301 302 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0); 303 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0); 304 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL); 305 306 static struct attribute *ntc_attributes[] = { 307 &dev_attr_name.attr, 308 &sensor_dev_attr_temp1_type.dev_attr.attr, 309 &sensor_dev_attr_temp1_input.dev_attr.attr, 310 NULL, 311 }; 312 313 static const struct attribute_group ntc_attr_group = { 314 .attrs = ntc_attributes, 315 }; 316 317 static int __devinit ntc_thermistor_probe(struct platform_device *pdev) 318 { 319 struct ntc_data *data; 320 struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data; 321 int ret = 0; 322 323 if (!pdata) { 324 dev_err(&pdev->dev, "No platform init data supplied.\n"); 325 return -ENODEV; 326 } 327 328 /* Either one of the two is required. */ 329 if (!pdata->read_uV && !pdata->read_ohm) { 330 dev_err(&pdev->dev, "Both read_uV and read_ohm missing." 331 "Need either one of the two.\n"); 332 return -EINVAL; 333 } 334 335 if (pdata->read_uV && pdata->read_ohm) { 336 dev_warn(&pdev->dev, "Only one of read_uV and read_ohm " 337 "is needed; ignoring read_uV.\n"); 338 pdata->read_uV = NULL; 339 } 340 341 if (pdata->read_uV && (pdata->pullup_uV == 0 || 342 (pdata->pullup_ohm == 0 && pdata->connect == 343 NTC_CONNECTED_GROUND) || 344 (pdata->pulldown_ohm == 0 && pdata->connect == 345 NTC_CONNECTED_POSITIVE) || 346 (pdata->connect != NTC_CONNECTED_POSITIVE && 347 pdata->connect != NTC_CONNECTED_GROUND))) { 348 dev_err(&pdev->dev, "Required data to use read_uV not " 349 "supplied.\n"); 350 return -EINVAL; 351 } 352 353 data = kzalloc(sizeof(struct ntc_data), GFP_KERNEL); 354 if (!data) 355 return -ENOMEM; 356 357 data->dev = &pdev->dev; 358 data->pdata = pdata; 359 strncpy(data->name, pdev->id_entry->name, PLATFORM_NAME_SIZE); 360 361 switch (pdev->id_entry->driver_data) { 362 case TYPE_NCPXXWB473: 363 data->comp = ncpXXwb473; 364 data->n_comp = ARRAY_SIZE(ncpXXwb473); 365 break; 366 case TYPE_NCPXXWL333: 367 data->comp = ncpXXwl333; 368 data->n_comp = ARRAY_SIZE(ncpXXwl333); 369 break; 370 default: 371 dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n", 372 pdev->id_entry->driver_data, 373 pdev->id_entry->name); 374 ret = -EINVAL; 375 goto err; 376 } 377 378 platform_set_drvdata(pdev, data); 379 380 ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group); 381 if (ret) { 382 dev_err(data->dev, "unable to create sysfs files\n"); 383 goto err; 384 } 385 386 data->hwmon_dev = hwmon_device_register(data->dev); 387 if (IS_ERR_OR_NULL(data->hwmon_dev)) { 388 dev_err(data->dev, "unable to register as hwmon device.\n"); 389 ret = -EINVAL; 390 goto err_after_sysfs; 391 } 392 393 dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n", 394 pdev->name, pdev->id, pdev->id_entry->name, 395 pdev->id_entry->driver_data); 396 return 0; 397 err_after_sysfs: 398 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); 399 err: 400 kfree(data); 401 return ret; 402 } 403 404 static int __devexit ntc_thermistor_remove(struct platform_device *pdev) 405 { 406 struct ntc_data *data = platform_get_drvdata(pdev); 407 408 hwmon_device_unregister(data->hwmon_dev); 409 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); 410 platform_set_drvdata(pdev, NULL); 411 412 kfree(data); 413 414 return 0; 415 } 416 417 static const struct platform_device_id ntc_thermistor_id[] = { 418 { "ncp15wb473", TYPE_NCPXXWB473 }, 419 { "ncp18wb473", TYPE_NCPXXWB473 }, 420 { "ncp21wb473", TYPE_NCPXXWB473 }, 421 { "ncp03wb473", TYPE_NCPXXWB473 }, 422 { "ncp15wl333", TYPE_NCPXXWL333 }, 423 { }, 424 }; 425 426 static struct platform_driver ntc_thermistor_driver = { 427 .driver = { 428 .name = "ntc-thermistor", 429 .owner = THIS_MODULE, 430 }, 431 .probe = ntc_thermistor_probe, 432 .remove = __devexit_p(ntc_thermistor_remove), 433 .id_table = ntc_thermistor_id, 434 }; 435 436 static int __init ntc_thermistor_init(void) 437 { 438 return platform_driver_register(&ntc_thermistor_driver); 439 } 440 441 module_init(ntc_thermistor_init); 442 443 static void __exit ntc_thermistor_cleanup(void) 444 { 445 platform_driver_unregister(&ntc_thermistor_driver); 446 } 447 448 module_exit(ntc_thermistor_cleanup); 449 450 MODULE_DESCRIPTION("NTC Thermistor Driver"); 451 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 452 MODULE_LICENSE("GPL"); 453 MODULE_ALIAS("platform:ntc-thermistor"); 454