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 int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uV) 138 { 139 struct ntc_thermistor_platform_data *pdata = data->pdata; 140 u64 mV = uV / 1000; 141 u64 pmV = pdata->pullup_uV / 1000; 142 u64 N, puO, pdO; 143 puO = pdata->pullup_ohm; 144 pdO = pdata->pulldown_ohm; 145 146 if (mV == 0) { 147 if (pdata->connect == NTC_CONNECTED_POSITIVE) 148 return INT_MAX; 149 return 0; 150 } 151 if (mV >= pmV) 152 return (pdata->connect == NTC_CONNECTED_POSITIVE) ? 153 0 : INT_MAX; 154 155 if (pdata->connect == NTC_CONNECTED_POSITIVE && puO == 0) 156 N = div64_u64_safe(pdO * (pmV - mV), mV); 157 else if (pdata->connect == NTC_CONNECTED_GROUND && pdO == 0) 158 N = div64_u64_safe(puO * mV, pmV - mV); 159 else if (pdata->connect == NTC_CONNECTED_POSITIVE) 160 N = div64_u64_safe(pdO * puO * (pmV - mV), 161 puO * mV - pdO * (pmV - mV)); 162 else 163 N = div64_u64_safe(pdO * puO * mV, pdO * (pmV - mV) - puO * mV); 164 165 if (N > INT_MAX) 166 N = INT_MAX; 167 return N; 168 } 169 170 static void lookup_comp(struct ntc_data *data, unsigned int ohm, 171 int *i_low, int *i_high) 172 { 173 int start, end, mid; 174 175 /* 176 * Handle special cases: Resistance is higher than or equal to 177 * resistance in first table entry, or resistance is lower or equal 178 * to resistance in last table entry. 179 * In these cases, return i_low == i_high, either pointing to the 180 * beginning or to the end of the table depending on the condition. 181 */ 182 if (ohm >= data->comp[0].ohm) { 183 *i_low = 0; 184 *i_high = 0; 185 return; 186 } 187 if (ohm <= data->comp[data->n_comp - 1].ohm) { 188 *i_low = data->n_comp - 1; 189 *i_high = data->n_comp - 1; 190 return; 191 } 192 193 /* Do a binary search on compensation table */ 194 start = 0; 195 end = data->n_comp; 196 while (start < end) { 197 mid = start + (end - start) / 2; 198 /* 199 * start <= mid < end 200 * data->comp[start].ohm > ohm >= data->comp[end].ohm 201 * 202 * We could check for "ohm == data->comp[mid].ohm" here, but 203 * that is a quite unlikely condition, and we would have to 204 * check again after updating start. Check it at the end instead 205 * for simplicity. 206 */ 207 if (ohm >= data->comp[mid].ohm) { 208 end = mid; 209 } else { 210 start = mid + 1; 211 /* 212 * ohm >= data->comp[start].ohm might be true here, 213 * since we set start to mid + 1. In that case, we are 214 * done. We could keep going, but the condition is quite 215 * likely to occur, so it is worth checking for it. 216 */ 217 if (ohm >= data->comp[start].ohm) 218 end = start; 219 } 220 /* 221 * start <= end 222 * data->comp[start].ohm >= ohm >= data->comp[end].ohm 223 */ 224 } 225 /* 226 * start == end 227 * ohm >= data->comp[end].ohm 228 */ 229 *i_low = end; 230 if (ohm == data->comp[end].ohm) 231 *i_high = end; 232 else 233 *i_high = end - 1; 234 } 235 236 static int get_temp_mC(struct ntc_data *data, unsigned int ohm) 237 { 238 int low, high; 239 int temp; 240 241 lookup_comp(data, ohm, &low, &high); 242 if (low == high) { 243 /* Unable to use linear approximation */ 244 temp = data->comp[low].temp_C * 1000; 245 } else { 246 temp = data->comp[low].temp_C * 1000 + 247 ((data->comp[high].temp_C - data->comp[low].temp_C) * 248 1000 * ((int)ohm - (int)data->comp[low].ohm)) / 249 ((int)data->comp[high].ohm - (int)data->comp[low].ohm); 250 } 251 return temp; 252 } 253 254 static int ntc_thermistor_get_ohm(struct ntc_data *data) 255 { 256 int read_uV; 257 258 if (data->pdata->read_ohm) 259 return data->pdata->read_ohm(); 260 261 if (data->pdata->read_uV) { 262 read_uV = data->pdata->read_uV(); 263 if (read_uV < 0) 264 return read_uV; 265 return get_ohm_of_thermistor(data, read_uV); 266 } 267 return -EINVAL; 268 } 269 270 static ssize_t ntc_show_name(struct device *dev, 271 struct device_attribute *attr, char *buf) 272 { 273 struct ntc_data *data = dev_get_drvdata(dev); 274 275 return sprintf(buf, "%s\n", data->name); 276 } 277 278 static ssize_t ntc_show_type(struct device *dev, 279 struct device_attribute *attr, char *buf) 280 { 281 return sprintf(buf, "4\n"); 282 } 283 284 static ssize_t ntc_show_temp(struct device *dev, 285 struct device_attribute *attr, char *buf) 286 { 287 struct ntc_data *data = dev_get_drvdata(dev); 288 int ohm; 289 290 ohm = ntc_thermistor_get_ohm(data); 291 if (ohm < 0) 292 return ohm; 293 294 return sprintf(buf, "%d\n", get_temp_mC(data, ohm)); 295 } 296 297 static SENSOR_DEVICE_ATTR(temp1_type, S_IRUGO, ntc_show_type, NULL, 0); 298 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ntc_show_temp, NULL, 0); 299 static DEVICE_ATTR(name, S_IRUGO, ntc_show_name, NULL); 300 301 static struct attribute *ntc_attributes[] = { 302 &dev_attr_name.attr, 303 &sensor_dev_attr_temp1_type.dev_attr.attr, 304 &sensor_dev_attr_temp1_input.dev_attr.attr, 305 NULL, 306 }; 307 308 static const struct attribute_group ntc_attr_group = { 309 .attrs = ntc_attributes, 310 }; 311 312 static int ntc_thermistor_probe(struct platform_device *pdev) 313 { 314 struct ntc_data *data; 315 struct ntc_thermistor_platform_data *pdata = pdev->dev.platform_data; 316 int ret = 0; 317 318 if (!pdata) { 319 dev_err(&pdev->dev, "No platform init data supplied.\n"); 320 return -ENODEV; 321 } 322 323 /* Either one of the two is required. */ 324 if (!pdata->read_uV && !pdata->read_ohm) { 325 dev_err(&pdev->dev, 326 "Both read_uV and read_ohm missing. Need either one of the two.\n"); 327 return -EINVAL; 328 } 329 330 if (pdata->read_uV && pdata->read_ohm) { 331 dev_warn(&pdev->dev, 332 "Only one of read_uV and read_ohm is needed; ignoring read_uV.\n"); 333 pdata->read_uV = NULL; 334 } 335 336 if (pdata->read_uV && (pdata->pullup_uV == 0 || 337 (pdata->pullup_ohm == 0 && pdata->connect == 338 NTC_CONNECTED_GROUND) || 339 (pdata->pulldown_ohm == 0 && pdata->connect == 340 NTC_CONNECTED_POSITIVE) || 341 (pdata->connect != NTC_CONNECTED_POSITIVE && 342 pdata->connect != NTC_CONNECTED_GROUND))) { 343 dev_err(&pdev->dev, 344 "Required data to use read_uV not supplied.\n"); 345 return -EINVAL; 346 } 347 348 data = devm_kzalloc(&pdev->dev, sizeof(struct ntc_data), GFP_KERNEL); 349 if (!data) 350 return -ENOMEM; 351 352 data->dev = &pdev->dev; 353 data->pdata = pdata; 354 strlcpy(data->name, pdev->id_entry->name, sizeof(data->name)); 355 356 switch (pdev->id_entry->driver_data) { 357 case TYPE_NCPXXWB473: 358 data->comp = ncpXXwb473; 359 data->n_comp = ARRAY_SIZE(ncpXXwb473); 360 break; 361 case TYPE_NCPXXWL333: 362 data->comp = ncpXXwl333; 363 data->n_comp = ARRAY_SIZE(ncpXXwl333); 364 break; 365 default: 366 dev_err(&pdev->dev, "Unknown device type: %lu(%s)\n", 367 pdev->id_entry->driver_data, 368 pdev->id_entry->name); 369 return -EINVAL; 370 } 371 372 platform_set_drvdata(pdev, data); 373 374 ret = sysfs_create_group(&data->dev->kobj, &ntc_attr_group); 375 if (ret) { 376 dev_err(data->dev, "unable to create sysfs files\n"); 377 return ret; 378 } 379 380 data->hwmon_dev = hwmon_device_register(data->dev); 381 if (IS_ERR(data->hwmon_dev)) { 382 dev_err(data->dev, "unable to register as hwmon device.\n"); 383 ret = PTR_ERR(data->hwmon_dev); 384 goto err_after_sysfs; 385 } 386 387 dev_info(&pdev->dev, "Thermistor %s:%d (type: %s/%lu) successfully probed.\n", 388 pdev->name, pdev->id, pdev->id_entry->name, 389 pdev->id_entry->driver_data); 390 return 0; 391 err_after_sysfs: 392 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); 393 return ret; 394 } 395 396 static int ntc_thermistor_remove(struct platform_device *pdev) 397 { 398 struct ntc_data *data = platform_get_drvdata(pdev); 399 400 hwmon_device_unregister(data->hwmon_dev); 401 sysfs_remove_group(&data->dev->kobj, &ntc_attr_group); 402 platform_set_drvdata(pdev, NULL); 403 404 return 0; 405 } 406 407 static const struct platform_device_id ntc_thermistor_id[] = { 408 { "ncp15wb473", TYPE_NCPXXWB473 }, 409 { "ncp18wb473", TYPE_NCPXXWB473 }, 410 { "ncp21wb473", TYPE_NCPXXWB473 }, 411 { "ncp03wb473", TYPE_NCPXXWB473 }, 412 { "ncp15wl333", TYPE_NCPXXWL333 }, 413 { }, 414 }; 415 416 static struct platform_driver ntc_thermistor_driver = { 417 .driver = { 418 .name = "ntc-thermistor", 419 .owner = THIS_MODULE, 420 }, 421 .probe = ntc_thermistor_probe, 422 .remove = ntc_thermistor_remove, 423 .id_table = ntc_thermistor_id, 424 }; 425 426 module_platform_driver(ntc_thermistor_driver); 427 428 MODULE_DESCRIPTION("NTC Thermistor Driver"); 429 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 430 MODULE_LICENSE("GPL"); 431 MODULE_ALIAS("platform:ntc-thermistor"); 432