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