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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * ntc_thermistor.c - NTC Thermistors
4 *
5 * Copyright (C) 2010 Samsung Electronics
6 * MyungJoo Ham <myungjoo.ham@samsung.com>
7 */
8
9#include <linux/slab.h>
10#include <linux/module.h>
11#include <linux/math64.h>
12#include <linux/mod_devicetable.h>
13#include <linux/platform_device.h>
14#include <linux/property.h>
15#include <linux/err.h>
16#include <linux/fixp-arith.h>
17#include <linux/iio/consumer.h>
18#include <linux/hwmon.h>
19
20enum ntc_thermistor_type {
21 TYPE_B57330V2103,
22 TYPE_B57891S0103,
23 TYPE_NCPXXWB473,
24 TYPE_NCPXXWF104,
25 TYPE_NCPXXWL333,
26 TYPE_NCPXXXH103,
27};
28
29struct ntc_compensation {
30 int temp_c;
31 unsigned int ohm;
32};
33
34/*
35 * Used as index in a zero-terminated array, holes not allowed so
36 * that NTC_LAST is the first empty array entry.
37 */
38enum {
39 NTC_B57330V2103,
40 NTC_B57891S0103,
41 NTC_NCP03WB473,
42 NTC_NCP03WF104,
43 NTC_NCP15WB473,
44 NTC_NCP15WL333,
45 NTC_NCP15XH103,
46 NTC_NCP18WB473,
47 NTC_NCP21WB473,
48 NTC_SSG1404001221,
49 NTC_LAST,
50};
51
52static const struct platform_device_id ntc_thermistor_id[] = {
53 [NTC_B57330V2103] = { "b57330v2103", TYPE_B57330V2103 },
54 [NTC_B57891S0103] = { "b57891s0103", TYPE_B57891S0103 },
55 [NTC_NCP03WB473] = { "ncp03wb473", TYPE_NCPXXWB473 },
56 [NTC_NCP03WF104] = { "ncp03wf104", TYPE_NCPXXWF104 },
57 [NTC_NCP15WB473] = { "ncp15wb473", TYPE_NCPXXWB473 },
58 [NTC_NCP15WL333] = { "ncp15wl333", TYPE_NCPXXWL333 },
59 [NTC_NCP15XH103] = { "ncp15xh103", TYPE_NCPXXXH103 },
60 [NTC_NCP18WB473] = { "ncp18wb473", TYPE_NCPXXWB473 },
61 [NTC_NCP21WB473] = { "ncp21wb473", TYPE_NCPXXWB473 },
62 [NTC_SSG1404001221] = { "ssg1404_001221", TYPE_NCPXXWB473 },
63 [NTC_LAST] = { },
64};
65
66/*
67 * A compensation table should be sorted by the values of .ohm
68 * in descending order.
69 * The following compensation tables are from the specification of Murata NTC
70 * Thermistors Datasheet
71 */
72static const struct ntc_compensation ncpXXwb473[] = {
73 { .temp_c = -40, .ohm = 1747920 },
74 { .temp_c = -35, .ohm = 1245428 },
75 { .temp_c = -30, .ohm = 898485 },
76 { .temp_c = -25, .ohm = 655802 },
77 { .temp_c = -20, .ohm = 483954 },
78 { .temp_c = -15, .ohm = 360850 },
79 { .temp_c = -10, .ohm = 271697 },
80 { .temp_c = -5, .ohm = 206463 },
81 { .temp_c = 0, .ohm = 158214 },
82 { .temp_c = 5, .ohm = 122259 },
83 { .temp_c = 10, .ohm = 95227 },
84 { .temp_c = 15, .ohm = 74730 },
85 { .temp_c = 20, .ohm = 59065 },
86 { .temp_c = 25, .ohm = 47000 },
87 { .temp_c = 30, .ohm = 37643 },
88 { .temp_c = 35, .ohm = 30334 },
89 { .temp_c = 40, .ohm = 24591 },
90 { .temp_c = 45, .ohm = 20048 },
91 { .temp_c = 50, .ohm = 16433 },
92 { .temp_c = 55, .ohm = 13539 },
93 { .temp_c = 60, .ohm = 11209 },
94 { .temp_c = 65, .ohm = 9328 },
95 { .temp_c = 70, .ohm = 7798 },
96 { .temp_c = 75, .ohm = 6544 },
97 { .temp_c = 80, .ohm = 5518 },
98 { .temp_c = 85, .ohm = 4674 },
99 { .temp_c = 90, .ohm = 3972 },
100 { .temp_c = 95, .ohm = 3388 },
101 { .temp_c = 100, .ohm = 2902 },
102 { .temp_c = 105, .ohm = 2494 },
103 { .temp_c = 110, .ohm = 2150 },
104 { .temp_c = 115, .ohm = 1860 },
105 { .temp_c = 120, .ohm = 1615 },
106 { .temp_c = 125, .ohm = 1406 },
107};
108static const struct ntc_compensation ncpXXwl333[] = {
109 { .temp_c = -40, .ohm = 1610154 },
110 { .temp_c = -35, .ohm = 1130850 },
111 { .temp_c = -30, .ohm = 802609 },
112 { .temp_c = -25, .ohm = 575385 },
113 { .temp_c = -20, .ohm = 416464 },
114 { .temp_c = -15, .ohm = 304219 },
115 { .temp_c = -10, .ohm = 224193 },
116 { .temp_c = -5, .ohm = 166623 },
117 { .temp_c = 0, .ohm = 124850 },
118 { .temp_c = 5, .ohm = 94287 },
119 { .temp_c = 10, .ohm = 71747 },
120 { .temp_c = 15, .ohm = 54996 },
121 { .temp_c = 20, .ohm = 42455 },
122 { .temp_c = 25, .ohm = 33000 },
123 { .temp_c = 30, .ohm = 25822 },
124 { .temp_c = 35, .ohm = 20335 },
125 { .temp_c = 40, .ohm = 16115 },
126 { .temp_c = 45, .ohm = 12849 },
127 { .temp_c = 50, .ohm = 10306 },
128 { .temp_c = 55, .ohm = 8314 },
129 { .temp_c = 60, .ohm = 6746 },
130 { .temp_c = 65, .ohm = 5503 },
131 { .temp_c = 70, .ohm = 4513 },
132 { .temp_c = 75, .ohm = 3721 },
133 { .temp_c = 80, .ohm = 3084 },
134 { .temp_c = 85, .ohm = 2569 },
135 { .temp_c = 90, .ohm = 2151 },
136 { .temp_c = 95, .ohm = 1809 },
137 { .temp_c = 100, .ohm = 1529 },
138 { .temp_c = 105, .ohm = 1299 },
139 { .temp_c = 110, .ohm = 1108 },
140 { .temp_c = 115, .ohm = 949 },
141 { .temp_c = 120, .ohm = 817 },
142 { .temp_c = 125, .ohm = 707 },
143};
144
145static const struct ntc_compensation ncpXXwf104[] = {
146 { .temp_c = -40, .ohm = 4397119 },
147 { .temp_c = -35, .ohm = 3088599 },
148 { .temp_c = -30, .ohm = 2197225 },
149 { .temp_c = -25, .ohm = 1581881 },
150 { .temp_c = -20, .ohm = 1151037 },
151 { .temp_c = -15, .ohm = 846579 },
152 { .temp_c = -10, .ohm = 628988 },
153 { .temp_c = -5, .ohm = 471632 },
154 { .temp_c = 0, .ohm = 357012 },
155 { .temp_c = 5, .ohm = 272500 },
156 { .temp_c = 10, .ohm = 209710 },
157 { .temp_c = 15, .ohm = 162651 },
158 { .temp_c = 20, .ohm = 127080 },
159 { .temp_c = 25, .ohm = 100000 },
160 { .temp_c = 30, .ohm = 79222 },
161 { .temp_c = 35, .ohm = 63167 },
162 { .temp_c = 40, .ohm = 50677 },
163 { .temp_c = 45, .ohm = 40904 },
164 { .temp_c = 50, .ohm = 33195 },
165 { .temp_c = 55, .ohm = 27091 },
166 { .temp_c = 60, .ohm = 22224 },
167 { .temp_c = 65, .ohm = 18323 },
168 { .temp_c = 70, .ohm = 15184 },
169 { .temp_c = 75, .ohm = 12635 },
170 { .temp_c = 80, .ohm = 10566 },
171 { .temp_c = 85, .ohm = 8873 },
172 { .temp_c = 90, .ohm = 7481 },
173 { .temp_c = 95, .ohm = 6337 },
174 { .temp_c = 100, .ohm = 5384 },
175 { .temp_c = 105, .ohm = 4594 },
176 { .temp_c = 110, .ohm = 3934 },
177 { .temp_c = 115, .ohm = 3380 },
178 { .temp_c = 120, .ohm = 2916 },
179 { .temp_c = 125, .ohm = 2522 },
180};
181
182static const struct ntc_compensation ncpXXxh103[] = {
183 { .temp_c = -40, .ohm = 247565 },
184 { .temp_c = -35, .ohm = 181742 },
185 { .temp_c = -30, .ohm = 135128 },
186 { .temp_c = -25, .ohm = 101678 },
187 { .temp_c = -20, .ohm = 77373 },
188 { .temp_c = -15, .ohm = 59504 },
189 { .temp_c = -10, .ohm = 46222 },
190 { .temp_c = -5, .ohm = 36244 },
191 { .temp_c = 0, .ohm = 28674 },
192 { .temp_c = 5, .ohm = 22878 },
193 { .temp_c = 10, .ohm = 18399 },
194 { .temp_c = 15, .ohm = 14910 },
195 { .temp_c = 20, .ohm = 12169 },
196 { .temp_c = 25, .ohm = 10000 },
197 { .temp_c = 30, .ohm = 8271 },
198 { .temp_c = 35, .ohm = 6883 },
199 { .temp_c = 40, .ohm = 5762 },
200 { .temp_c = 45, .ohm = 4851 },
201 { .temp_c = 50, .ohm = 4105 },
202 { .temp_c = 55, .ohm = 3492 },
203 { .temp_c = 60, .ohm = 2985 },
204 { .temp_c = 65, .ohm = 2563 },
205 { .temp_c = 70, .ohm = 2211 },
206 { .temp_c = 75, .ohm = 1915 },
207 { .temp_c = 80, .ohm = 1666 },
208 { .temp_c = 85, .ohm = 1454 },
209 { .temp_c = 90, .ohm = 1275 },
210 { .temp_c = 95, .ohm = 1121 },
211 { .temp_c = 100, .ohm = 990 },
212 { .temp_c = 105, .ohm = 876 },
213 { .temp_c = 110, .ohm = 779 },
214 { .temp_c = 115, .ohm = 694 },
215 { .temp_c = 120, .ohm = 620 },
216 { .temp_c = 125, .ohm = 556 },
217};
218
219/*
220 * The following compensation tables are from the specifications in EPCOS NTC
221 * Thermistors Datasheets
222 */
223static const struct ntc_compensation b57330v2103[] = {
224 { .temp_c = -40, .ohm = 190030 },
225 { .temp_c = -35, .ohm = 145360 },
226 { .temp_c = -30, .ohm = 112060 },
227 { .temp_c = -25, .ohm = 87041 },
228 { .temp_c = -20, .ohm = 68104 },
229 { .temp_c = -15, .ohm = 53665 },
230 { .temp_c = -10, .ohm = 42576 },
231 { .temp_c = -5, .ohm = 34001 },
232 { .temp_c = 0, .ohm = 27326 },
233 { .temp_c = 5, .ohm = 22096 },
234 { .temp_c = 10, .ohm = 17973 },
235 { .temp_c = 15, .ohm = 14703 },
236 { .temp_c = 20, .ohm = 12090 },
237 { .temp_c = 25, .ohm = 10000 },
238 { .temp_c = 30, .ohm = 8311 },
239 { .temp_c = 35, .ohm = 6941 },
240 { .temp_c = 40, .ohm = 5825 },
241 { .temp_c = 45, .ohm = 4911 },
242 { .temp_c = 50, .ohm = 4158 },
243 { .temp_c = 55, .ohm = 3536 },
244 { .temp_c = 60, .ohm = 3019 },
245 { .temp_c = 65, .ohm = 2588 },
246 { .temp_c = 70, .ohm = 2227 },
247 { .temp_c = 75, .ohm = 1924 },
248 { .temp_c = 80, .ohm = 1668 },
249 { .temp_c = 85, .ohm = 1451 },
250 { .temp_c = 90, .ohm = 1266 },
251 { .temp_c = 95, .ohm = 1108 },
252 { .temp_c = 100, .ohm = 973 },
253 { .temp_c = 105, .ohm = 857 },
254 { .temp_c = 110, .ohm = 757 },
255 { .temp_c = 115, .ohm = 671 },
256 { .temp_c = 120, .ohm = 596 },
257 { .temp_c = 125, .ohm = 531 },
258};
259
260static const struct ntc_compensation b57891s0103[] = {
261 { .temp_c = -55.0, .ohm = 878900 },
262 { .temp_c = -50.0, .ohm = 617590 },
263 { .temp_c = -45.0, .ohm = 439340 },
264 { .temp_c = -40.0, .ohm = 316180 },
265 { .temp_c = -35.0, .ohm = 230060 },
266 { .temp_c = -30.0, .ohm = 169150 },
267 { .temp_c = -25.0, .ohm = 125550 },
268 { .temp_c = -20.0, .ohm = 94143 },
269 { .temp_c = -15.0, .ohm = 71172 },
270 { .temp_c = -10.0, .ohm = 54308 },
271 { .temp_c = -5.0, .ohm = 41505 },
272 { .temp_c = 0.0, .ohm = 32014 },
273 { .temp_c = 5.0, .ohm = 25011 },
274 { .temp_c = 10.0, .ohm = 19691 },
275 { .temp_c = 15.0, .ohm = 15618 },
276 { .temp_c = 20.0, .ohm = 12474 },
277 { .temp_c = 25.0, .ohm = 10000 },
278 { .temp_c = 30.0, .ohm = 8080 },
279 { .temp_c = 35.0, .ohm = 6569 },
280 { .temp_c = 40.0, .ohm = 5372 },
281 { .temp_c = 45.0, .ohm = 4424 },
282 { .temp_c = 50.0, .ohm = 3661 },
283 { .temp_c = 55.0, .ohm = 3039 },
284 { .temp_c = 60.0, .ohm = 2536 },
285 { .temp_c = 65.0, .ohm = 2128 },
286 { .temp_c = 70.0, .ohm = 1794 },
287 { .temp_c = 75.0, .ohm = 1518 },
288 { .temp_c = 80.0, .ohm = 1290 },
289 { .temp_c = 85.0, .ohm = 1100 },
290 { .temp_c = 90.0, .ohm = 942 },
291 { .temp_c = 95.0, .ohm = 809 },
292 { .temp_c = 100.0, .ohm = 697 },
293 { .temp_c = 105.0, .ohm = 604 },
294 { .temp_c = 110.0, .ohm = 525 },
295 { .temp_c = 115.0, .ohm = 457 },
296 { .temp_c = 120.0, .ohm = 400 },
297 { .temp_c = 125.0, .ohm = 351 },
298 { .temp_c = 130.0, .ohm = 308 },
299 { .temp_c = 135.0, .ohm = 272 },
300 { .temp_c = 140.0, .ohm = 240 },
301 { .temp_c = 145.0, .ohm = 213 },
302 { .temp_c = 150.0, .ohm = 189 },
303 { .temp_c = 155.0, .ohm = 168 },
304};
305
306struct ntc_type {
307 const struct ntc_compensation *comp;
308 int n_comp;
309};
310
311#define NTC_TYPE(ntc, compensation) \
312[(ntc)] = { .comp = (compensation), .n_comp = ARRAY_SIZE(compensation) }
313
314static const struct ntc_type ntc_type[] = {
315 NTC_TYPE(TYPE_B57330V2103, b57330v2103),
316 NTC_TYPE(TYPE_B57891S0103, b57891s0103),
317 NTC_TYPE(TYPE_NCPXXWB473, ncpXXwb473),
318 NTC_TYPE(TYPE_NCPXXWF104, ncpXXwf104),
319 NTC_TYPE(TYPE_NCPXXWL333, ncpXXwl333),
320 NTC_TYPE(TYPE_NCPXXXH103, ncpXXxh103),
321};
322
323/*
324 * pullup_uV, pullup_ohm, pulldown_ohm, and connect are required.
325 *
326 * How to setup pullup_ohm, pulldown_ohm, and connect is
327 * described at Documentation/hwmon/ntc_thermistor.rst
328 *
329 * pullup/down_ohm: 0 for infinite / not-connected
330 *
331 * chan: iio_channel pointer to communicate with the ADC which the
332 * thermistor is using for conversion of the analog values.
333 */
334struct ntc_data {
335 const struct ntc_compensation *comp;
336 int n_comp;
337 unsigned int pullup_uv;
338 unsigned int pullup_ohm;
339 unsigned int pulldown_ohm;
340 enum { NTC_CONNECTED_POSITIVE, NTC_CONNECTED_GROUND } connect;
341 struct iio_channel *chan;
342};
343
344static int ntc_adc_iio_read(struct ntc_data *data)
345{
346 struct iio_channel *channel = data->chan;
347 int uv, ret;
348
349 ret = iio_read_channel_processed_scale(channel, &uv, 1000);
350 if (ret < 0) {
351 int raw;
352
353 /*
354 * This fallback uses a raw read and then
355 * assumes the ADC is 12 bits, scaling with
356 * a factor 1000 to get to microvolts.
357 */
358 ret = iio_read_channel_raw(channel, &raw);
359 if (ret < 0) {
360 pr_err("read channel() error: %d\n", ret);
361 return ret;
362 }
363 ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000);
364 if (ret < 0) {
365 /* Assume 12 bit ADC with vref at pullup_uv */
366 uv = (data->pullup_uv * (s64)raw) >> 12;
367 }
368 }
369
370 return uv;
371}
372
373static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
374{
375 if (divisor == 0 && dividend == 0)
376 return 0;
377 if (divisor == 0)
378 return UINT_MAX;
379 return div64_u64(dividend, divisor);
380}
381
382static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv)
383{
384 u32 puv = data->pullup_uv;
385 u64 n, puo, pdo;
386 puo = data->pullup_ohm;
387 pdo = data->pulldown_ohm;
388
389 if (uv == 0)
390 return (data->connect == NTC_CONNECTED_POSITIVE) ?
391 INT_MAX : 0;
392 if (uv >= puv)
393 return (data->connect == NTC_CONNECTED_POSITIVE) ?
394 0 : INT_MAX;
395
396 if (data->connect == NTC_CONNECTED_POSITIVE && puo == 0)
397 n = div_u64(pdo * (puv - uv), uv);
398 else if (data->connect == NTC_CONNECTED_GROUND && pdo == 0)
399 n = div_u64(puo * uv, puv - uv);
400 else if (data->connect == NTC_CONNECTED_POSITIVE)
401 n = div64_u64_safe(pdo * puo * (puv - uv),
402 puo * uv - pdo * (puv - uv));
403 else
404 n = div64_u64_safe(pdo * puo * uv, pdo * (puv - uv) - puo * uv);
405
406 if (n > INT_MAX)
407 n = INT_MAX;
408 return n;
409}
410
411static void lookup_comp(struct ntc_data *data, unsigned int ohm,
412 int *i_low, int *i_high)
413{
414 int start, end, mid;
415
416 /*
417 * Handle special cases: Resistance is higher than or equal to
418 * resistance in first table entry, or resistance is lower or equal
419 * to resistance in last table entry.
420 * In these cases, return i_low == i_high, either pointing to the
421 * beginning or to the end of the table depending on the condition.
422 */
423 if (ohm >= data->comp[0].ohm) {
424 *i_low = 0;
425 *i_high = 0;
426 return;
427 }
428 if (ohm <= data->comp[data->n_comp - 1].ohm) {
429 *i_low = data->n_comp - 1;
430 *i_high = data->n_comp - 1;
431 return;
432 }
433
434 /* Do a binary search on compensation table */
435 start = 0;
436 end = data->n_comp;
437 while (start < end) {
438 mid = start + (end - start) / 2;
439 /*
440 * start <= mid < end
441 * data->comp[start].ohm > ohm >= data->comp[end].ohm
442 *
443 * We could check for "ohm == data->comp[mid].ohm" here, but
444 * that is a quite unlikely condition, and we would have to
445 * check again after updating start. Check it at the end instead
446 * for simplicity.
447 */
448 if (ohm >= data->comp[mid].ohm) {
449 end = mid;
450 } else {
451 start = mid + 1;
452 /*
453 * ohm >= data->comp[start].ohm might be true here,
454 * since we set start to mid + 1. In that case, we are
455 * done. We could keep going, but the condition is quite
456 * likely to occur, so it is worth checking for it.
457 */
458 if (ohm >= data->comp[start].ohm)
459 end = start;
460 }
461 /*
462 * start <= end
463 * data->comp[start].ohm >= ohm >= data->comp[end].ohm
464 */
465 }
466 /*
467 * start == end
468 * ohm >= data->comp[end].ohm
469 */
470 *i_low = end;
471 if (ohm == data->comp[end].ohm)
472 *i_high = end;
473 else
474 *i_high = end - 1;
475}
476
477static int get_temp_mc(struct ntc_data *data, unsigned int ohm)
478{
479 int low, high;
480 int temp;
481
482 lookup_comp(data, ohm, &low, &high);
483 /*
484 * First multiplying the table temperatures with 1000 to get to
485 * millicentigrades (which is what we want) and then interpolating
486 * will give the best precision.
487 */
488 temp = fixp_linear_interpolate(data->comp[low].ohm,
489 data->comp[low].temp_c * 1000,
490 data->comp[high].ohm,
491 data->comp[high].temp_c * 1000,
492 ohm);
493 return temp;
494}
495
496static int ntc_thermistor_get_ohm(struct ntc_data *data)
497{
498 int read_uv;
499
500 read_uv = ntc_adc_iio_read(data);
501 if (read_uv < 0)
502 return read_uv;
503 return get_ohm_of_thermistor(data, read_uv);
504}
505
506static int ntc_read(struct device *dev, enum hwmon_sensor_types type,
507 u32 attr, int channel, long *val)
508{
509 struct ntc_data *data = dev_get_drvdata(dev);
510 int ohm;
511
512 switch (type) {
513 case hwmon_temp:
514 switch (attr) {
515 case hwmon_temp_input:
516 ohm = ntc_thermistor_get_ohm(data);
517 if (ohm < 0)
518 return ohm;
519 *val = get_temp_mc(data, ohm);
520 return 0;
521 case hwmon_temp_type:
522 *val = 4;
523 return 0;
524 default:
525 break;
526 }
527 break;
528 default:
529 break;
530 }
531 return -EINVAL;
532}
533
534static umode_t ntc_is_visible(const void *data, enum hwmon_sensor_types type,
535 u32 attr, int channel)
536{
537 if (type == hwmon_temp) {
538 switch (attr) {
539 case hwmon_temp_input:
540 case hwmon_temp_type:
541 return 0444;
542 default:
543 break;
544 }
545 }
546 return 0;
547}
548
549static const struct hwmon_channel_info * const ntc_info[] = {
550 HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
551 HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_TYPE),
552 NULL
553};
554
555static const struct hwmon_ops ntc_hwmon_ops = {
556 .is_visible = ntc_is_visible,
557 .read = ntc_read,
558};
559
560static const struct hwmon_chip_info ntc_chip_info = {
561 .ops = &ntc_hwmon_ops,
562 .info = ntc_info,
563};
564
565static int ntc_thermistor_parse_props(struct device *dev,
566 struct ntc_data *data)
567{
568 struct iio_channel *chan;
569 enum iio_chan_type type;
570 int ret;
571
572 chan = devm_iio_channel_get(dev, NULL);
573 if (IS_ERR(chan))
574 return PTR_ERR(chan);
575
576 ret = iio_get_channel_type(chan, &type);
577 if (ret < 0)
578 return ret;
579
580 if (type != IIO_VOLTAGE)
581 return -EINVAL;
582
583 ret = device_property_read_u32(dev, "pullup-uv", &data->pullup_uv);
584 if (ret)
585 return dev_err_probe(dev, ret, "pullup-uv not specified\n");
586
587 ret = device_property_read_u32(dev, "pullup-ohm", &data->pullup_ohm);
588 if (ret)
589 return dev_err_probe(dev, ret, "pullup-ohm not specified\n");
590
591 ret = device_property_read_u32(dev, "pulldown-ohm", &data->pulldown_ohm);
592 if (ret)
593 return dev_err_probe(dev, ret, "pulldown-ohm not specified\n");
594
595 if (device_property_read_bool(dev, "connected-positive"))
596 data->connect = NTC_CONNECTED_POSITIVE;
597 else /* status change should be possible if not always on. */
598 data->connect = NTC_CONNECTED_GROUND;
599
600 data->chan = chan;
601
602 return 0;
603}
604
605static int ntc_thermistor_probe(struct platform_device *pdev)
606{
607 struct device *dev = &pdev->dev;
608 const struct platform_device_id *pdev_id;
609 struct device *hwmon_dev;
610 struct ntc_data *data;
611 int ret;
612
613 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
614 if (!data)
615 return -ENOMEM;
616
617 ret = ntc_thermistor_parse_props(dev, data);
618 if (ret)
619 return ret;
620
621 if (data->pullup_uv == 0 ||
622 (data->pullup_ohm == 0 && data->connect ==
623 NTC_CONNECTED_GROUND) ||
624 (data->pulldown_ohm == 0 && data->connect ==
625 NTC_CONNECTED_POSITIVE) ||
626 (data->connect != NTC_CONNECTED_POSITIVE &&
627 data->connect != NTC_CONNECTED_GROUND)) {
628 dev_err(dev, "Required data to use NTC driver not supplied.\n");
629 return -EINVAL;
630 }
631
632 pdev_id = device_get_match_data(dev);
633
634 if (pdev_id->driver_data >= ARRAY_SIZE(ntc_type)) {
635 dev_err(dev, "Unknown device type: %lu(%s)\n",
636 pdev_id->driver_data, pdev_id->name);
637 return -EINVAL;
638 }
639
640 data->comp = ntc_type[pdev_id->driver_data].comp;
641 data->n_comp = ntc_type[pdev_id->driver_data].n_comp;
642
643 hwmon_dev = devm_hwmon_device_register_with_info(dev, pdev_id->name,
644 data, &ntc_chip_info,
645 NULL);
646 if (IS_ERR(hwmon_dev)) {
647 dev_err(dev, "unable to register as hwmon device.\n");
648 return PTR_ERR(hwmon_dev);
649 }
650
651 dev_info(dev, "Thermistor type: %s successfully probed.\n",
652 pdev_id->name);
653
654 return 0;
655}
656
657static const struct of_device_id ntc_match[] = {
658 { .compatible = "epcos,b57330v2103",
659 .data = &ntc_thermistor_id[NTC_B57330V2103]},
660 { .compatible = "epcos,b57891s0103",
661 .data = &ntc_thermistor_id[NTC_B57891S0103] },
662 { .compatible = "murata,ncp03wb473",
663 .data = &ntc_thermistor_id[NTC_NCP03WB473] },
664 { .compatible = "murata,ncp03wf104",
665 .data = &ntc_thermistor_id[NTC_NCP03WF104] },
666 { .compatible = "murata,ncp15wb473",
667 .data = &ntc_thermistor_id[NTC_NCP15WB473] },
668 { .compatible = "murata,ncp15wl333",
669 .data = &ntc_thermistor_id[NTC_NCP15WL333] },
670 { .compatible = "murata,ncp15xh103",
671 .data = &ntc_thermistor_id[NTC_NCP15XH103] },
672 { .compatible = "murata,ncp18wb473",
673 .data = &ntc_thermistor_id[NTC_NCP18WB473] },
674 { .compatible = "murata,ncp21wb473",
675 .data = &ntc_thermistor_id[NTC_NCP21WB473] },
676 { .compatible = "samsung,1404-001221",
677 .data = &ntc_thermistor_id[NTC_SSG1404001221] },
678
679 /* Usage of vendor name "ntc" is deprecated */
680 { .compatible = "ntc,ncp03wb473",
681 .data = &ntc_thermistor_id[NTC_NCP03WB473] },
682 { .compatible = "ntc,ncp15wb473",
683 .data = &ntc_thermistor_id[NTC_NCP15WB473] },
684 { .compatible = "ntc,ncp15wl333",
685 .data = &ntc_thermistor_id[NTC_NCP15WL333] },
686 { .compatible = "ntc,ncp18wb473",
687 .data = &ntc_thermistor_id[NTC_NCP18WB473] },
688 { .compatible = "ntc,ncp21wb473",
689 .data = &ntc_thermistor_id[NTC_NCP21WB473] },
690 { },
691};
692MODULE_DEVICE_TABLE(of, ntc_match);
693
694static struct platform_driver ntc_thermistor_driver = {
695 .driver = {
696 .name = "ntc-thermistor",
697 .of_match_table = ntc_match,
698 },
699 .probe = ntc_thermistor_probe,
700 .id_table = ntc_thermistor_id,
701};
702
703module_platform_driver(ntc_thermistor_driver);
704
705MODULE_DESCRIPTION("NTC Thermistor Driver");
706MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
707MODULE_LICENSE("GPL");
708MODULE_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");