summaryrefslogtreecommitdiff
path: root/drivers/hwmon/ntc_thermistor.c
blob: e4f9f7ce92fabc7c5f10aebaf5d69d350da565d2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
/*
 * ntc_thermistor.c - NTC Thermistors
 *
 *  Copyright (C) 2010 Samsung Electronics
 *  MyungJoo Ham <myungjoo.ham@samsung.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include <linux/slab.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/math64.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/of_device.h>

#include <linux/platform_data/ntc_thermistor.h>

#include <linux/iio/iio.h>
#include <linux/iio/machine.h>
#include <linux/iio/driver.h>
#include <linux/iio/consumer.h>

#include <linux/hwmon.h>

struct ntc_compensation {
	int		temp_c;
	unsigned int	ohm;
};

/*
 * Used as index in a zero-terminated array, holes not allowed so
 * that NTC_LAST is the first empty array entry.
 */
enum {
	NTC_B57330V2103,
	NTC_B57891S0103,
	NTC_NCP03WB473,
	NTC_NCP03WF104,
	NTC_NCP15WB473,
	NTC_NCP15WL333,
	NTC_NCP15XH103,
	NTC_NCP18WB473,
	NTC_NCP21WB473,
	NTC_LAST,
};

static const struct platform_device_id ntc_thermistor_id[] = {
	[NTC_B57330V2103]     = { "b57330v2103",     TYPE_B57330V2103 },
	[NTC_B57891S0103]     = { "b57891s0103",     TYPE_B57891S0103 },
	[NTC_NCP03WB473]      = { "ncp03wb473",      TYPE_NCPXXWB473 },
	[NTC_NCP03WF104]      = { "ncp03wf104",      TYPE_NCPXXWF104 },
	[NTC_NCP15WB473]      = { "ncp15wb473",      TYPE_NCPXXWB473 },
	[NTC_NCP15WL333]      = { "ncp15wl333",      TYPE_NCPXXWL333 },
	[NTC_NCP15XH103]      = { "ncp15xh103",      TYPE_NCPXXXH103 },
	[NTC_NCP18WB473]      = { "ncp18wb473",      TYPE_NCPXXWB473 },
	[NTC_NCP21WB473]      = { "ncp21wb473",      TYPE_NCPXXWB473 },
	[NTC_LAST]            = { },
};

/*
 * A compensation table should be sorted by the values of .ohm
 * in descending order.
 * The following compensation tables are from the specification of Murata NTC
 * Thermistors Datasheet
 */
static const struct ntc_compensation ncpXXwb473[] = {
	{ .temp_c	= -40, .ohm	= 1747920 },
	{ .temp_c	= -35, .ohm	= 1245428 },
	{ .temp_c	= -30, .ohm	= 898485 },
	{ .temp_c	= -25, .ohm	= 655802 },
	{ .temp_c	= -20, .ohm	= 483954 },
	{ .temp_c	= -15, .ohm	= 360850 },
	{ .temp_c	= -10, .ohm	= 271697 },
	{ .temp_c	= -5, .ohm	= 206463 },
	{ .temp_c	= 0, .ohm	= 158214 },
	{ .temp_c	= 5, .ohm	= 122259 },
	{ .temp_c	= 10, .ohm	= 95227 },
	{ .temp_c	= 15, .ohm	= 74730 },
	{ .temp_c	= 20, .ohm	= 59065 },
	{ .temp_c	= 25, .ohm	= 47000 },
	{ .temp_c	= 30, .ohm	= 37643 },
	{ .temp_c	= 35, .ohm	= 30334 },
	{ .temp_c	= 40, .ohm	= 24591 },
	{ .temp_c	= 45, .ohm	= 20048 },
	{ .temp_c	= 50, .ohm	= 16433 },
	{ .temp_c	= 55, .ohm	= 13539 },
	{ .temp_c	= 60, .ohm	= 11209 },
	{ .temp_c	= 65, .ohm	= 9328 },
	{ .temp_c	= 70, .ohm	= 7798 },
	{ .temp_c	= 75, .ohm	= 6544 },
	{ .temp_c	= 80, .ohm	= 5518 },
	{ .temp_c	= 85, .ohm	= 4674 },
	{ .temp_c	= 90, .ohm	= 3972 },
	{ .temp_c	= 95, .ohm	= 3388 },
	{ .temp_c	= 100, .ohm	= 2902 },
	{ .temp_c	= 105, .ohm	= 2494 },
	{ .temp_c	= 110, .ohm	= 2150 },
	{ .temp_c	= 115, .ohm	= 1860 },
	{ .temp_c	= 120, .ohm	= 1615 },
	{ .temp_c	= 125, .ohm	= 1406 },
};
static const struct ntc_compensation ncpXXwl333[] = {
	{ .temp_c	= -40, .ohm	= 1610154 },
	{ .temp_c	= -35, .ohm	= 1130850 },
	{ .temp_c	= -30, .ohm	= 802609 },
	{ .temp_c	= -25, .ohm	= 575385 },
	{ .temp_c	= -20, .ohm	= 416464 },
	{ .temp_c	= -15, .ohm	= 304219 },
	{ .temp_c	= -10, .ohm	= 224193 },
	{ .temp_c	= -5, .ohm	= 166623 },
	{ .temp_c	= 0, .ohm	= 124850 },
	{ .temp_c	= 5, .ohm	= 94287 },
	{ .temp_c	= 10, .ohm	= 71747 },
	{ .temp_c	= 15, .ohm	= 54996 },
	{ .temp_c	= 20, .ohm	= 42455 },
	{ .temp_c	= 25, .ohm	= 33000 },
	{ .temp_c	= 30, .ohm	= 25822 },
	{ .temp_c	= 35, .ohm	= 20335 },
	{ .temp_c	= 40, .ohm	= 16115 },
	{ .temp_c	= 45, .ohm	= 12849 },
	{ .temp_c	= 50, .ohm	= 10306 },
	{ .temp_c	= 55, .ohm	= 8314 },
	{ .temp_c	= 60, .ohm	= 6746 },
	{ .temp_c	= 65, .ohm	= 5503 },
	{ .temp_c	= 70, .ohm	= 4513 },
	{ .temp_c	= 75, .ohm	= 3721 },
	{ .temp_c	= 80, .ohm	= 3084 },
	{ .temp_c	= 85, .ohm	= 2569 },
	{ .temp_c	= 90, .ohm	= 2151 },
	{ .temp_c	= 95, .ohm	= 1809 },
	{ .temp_c	= 100, .ohm	= 1529 },
	{ .temp_c	= 105, .ohm	= 1299 },
	{ .temp_c	= 110, .ohm	= 1108 },
	{ .temp_c	= 115, .ohm	= 949 },
	{ .temp_c	= 120, .ohm	= 817 },
	{ .temp_c	= 125, .ohm	= 707 },
};

static const struct ntc_compensation ncpXXwf104[] = {
	{ .temp_c	= -40, .ohm	= 4397119 },
	{ .temp_c	= -35, .ohm	= 3088599 },
	{ .temp_c	= -30, .ohm	= 2197225 },
	{ .temp_c	= -25, .ohm	= 1581881 },
	{ .temp_c	= -20, .ohm	= 1151037 },
	{ .temp_c	= -15, .ohm	= 846579 },
	{ .temp_c	= -10, .ohm	= 628988 },
	{ .temp_c	= -5, .ohm	= 471632 },
	{ .temp_c	= 0, .ohm	= 357012 },
	{ .temp_c	= 5, .ohm	= 272500 },
	{ .temp_c	= 10, .ohm	= 209710 },
	{ .temp_c	= 15, .ohm	= 162651 },
	{ .temp_c	= 20, .ohm	= 127080 },
	{ .temp_c	= 25, .ohm	= 100000 },
	{ .temp_c	= 30, .ohm	= 79222 },
	{ .temp_c	= 35, .ohm	= 63167 },
	{ .temp_c	= 40, .ohm	= 50677 },
	{ .temp_c	= 45, .ohm	= 40904 },
	{ .temp_c	= 50, .ohm	= 33195 },
	{ .temp_c	= 55, .ohm	= 27091 },
	{ .temp_c	= 60, .ohm	= 22224 },
	{ .temp_c	= 65, .ohm	= 18323 },
	{ .temp_c	= 70, .ohm	= 15184 },
	{ .temp_c	= 75, .ohm	= 12635 },
	{ .temp_c	= 80, .ohm	= 10566 },
	{ .temp_c	= 85, .ohm	= 8873 },
	{ .temp_c	= 90, .ohm	= 7481 },
	{ .temp_c	= 95, .ohm	= 6337 },
	{ .temp_c	= 100, .ohm	= 5384 },
	{ .temp_c	= 105, .ohm	= 4594 },
	{ .temp_c	= 110, .ohm	= 3934 },
	{ .temp_c	= 115, .ohm	= 3380 },
	{ .temp_c	= 120, .ohm	= 2916 },
	{ .temp_c	= 125, .ohm	= 2522 },
};

static const struct ntc_compensation ncpXXxh103[] = {
	{ .temp_c	= -40, .ohm	= 247565 },
	{ .temp_c	= -35, .ohm	= 181742 },
	{ .temp_c	= -30, .ohm	= 135128 },
	{ .temp_c	= -25, .ohm	= 101678 },
	{ .temp_c	= -20, .ohm	= 77373 },
	{ .temp_c	= -15, .ohm	= 59504 },
	{ .temp_c	= -10, .ohm	= 46222 },
	{ .temp_c	= -5, .ohm	= 36244 },
	{ .temp_c	= 0, .ohm	= 28674 },
	{ .temp_c	= 5, .ohm	= 22878 },
	{ .temp_c	= 10, .ohm	= 18399 },
	{ .temp_c	= 15, .ohm	= 14910 },
	{ .temp_c	= 20, .ohm	= 12169 },
	{ .temp_c	= 25, .ohm	= 10000 },
	{ .temp_c	= 30, .ohm	= 8271 },
	{ .temp_c	= 35, .ohm	= 6883 },
	{ .temp_c	= 40, .ohm	= 5762 },
	{ .temp_c	= 45, .ohm	= 4851 },
	{ .temp_c	= 50, .ohm	= 4105 },
	{ .temp_c	= 55, .ohm	= 3492 },
	{ .temp_c	= 60, .ohm	= 2985 },
	{ .temp_c	= 65, .ohm	= 2563 },
	{ .temp_c	= 70, .ohm	= 2211 },
	{ .temp_c	= 75, .ohm	= 1915 },
	{ .temp_c	= 80, .ohm	= 1666 },
	{ .temp_c	= 85, .ohm	= 1454 },
	{ .temp_c	= 90, .ohm	= 1275 },
	{ .temp_c	= 95, .ohm	= 1121 },
	{ .temp_c	= 100, .ohm	= 990 },
	{ .temp_c	= 105, .ohm	= 876 },
	{ .temp_c	= 110, .ohm	= 779 },
	{ .temp_c	= 115, .ohm	= 694 },
	{ .temp_c	= 120, .ohm	= 620 },
	{ .temp_c	= 125, .ohm	= 556 },
};

/*
 * The following compensation tables are from the specifications in EPCOS NTC
 * Thermistors Datasheets
 */
static const struct ntc_compensation b57330v2103[] = {
	{ .temp_c	= -40, .ohm	= 190030 },
	{ .temp_c	= -35, .ohm	= 145360 },
	{ .temp_c	= -30, .ohm	= 112060 },
	{ .temp_c	= -25, .ohm	= 87041 },
	{ .temp_c	= -20, .ohm	= 68104 },
	{ .temp_c	= -15, .ohm	= 53665 },
	{ .temp_c	= -10, .ohm	= 42576 },
	{ .temp_c	= -5, .ohm	= 34001 },
	{ .temp_c	= 0, .ohm	= 27326 },
	{ .temp_c	= 5, .ohm	= 22096 },
	{ .temp_c	= 10, .ohm	= 17973 },
	{ .temp_c	= 15, .ohm	= 14703 },
	{ .temp_c	= 20, .ohm	= 12090 },
	{ .temp_c	= 25, .ohm	= 10000 },
	{ .temp_c	= 30, .ohm	= 8311 },
	{ .temp_c	= 35, .ohm	= 6941 },
	{ .temp_c	= 40, .ohm	= 5825 },
	{ .temp_c	= 45, .ohm	= 4911 },
	{ .temp_c	= 50, .ohm	= 4158 },
	{ .temp_c	= 55, .ohm	= 3536 },
	{ .temp_c	= 60, .ohm	= 3019 },
	{ .temp_c	= 65, .ohm	= 2588 },
	{ .temp_c	= 70, .ohm	= 2227 },
	{ .temp_c	= 75, .ohm	= 1924 },
	{ .temp_c	= 80, .ohm	= 1668 },
	{ .temp_c	= 85, .ohm	= 1451 },
	{ .temp_c	= 90, .ohm	= 1266 },
	{ .temp_c	= 95, .ohm	= 1108 },
	{ .temp_c	= 100, .ohm	= 973 },
	{ .temp_c	= 105, .ohm	= 857 },
	{ .temp_c	= 110, .ohm	= 757 },
	{ .temp_c	= 115, .ohm	= 671 },
	{ .temp_c	= 120, .ohm	= 596 },
	{ .temp_c	= 125, .ohm	= 531 },
};

static const struct ntc_compensation b57891s0103[] = {
	{ .temp_c	= -55.0, .ohm	= 878900 },
	{ .temp_c	= -50.0, .ohm	= 617590 },
	{ .temp_c	= -45.0, .ohm	= 439340 },
	{ .temp_c	= -40.0, .ohm	= 316180 },
	{ .temp_c	= -35.0, .ohm	= 230060 },
	{ .temp_c	= -30.0, .ohm	= 169150 },
	{ .temp_c	= -25.0, .ohm	= 125550 },
	{ .temp_c	= -20.0, .ohm	= 94143 },
	{ .temp_c	= -15.0, .ohm	= 71172 },
	{ .temp_c	= -10.0, .ohm	= 54308 },
	{ .temp_c	= -5.0, .ohm	= 41505 },
	{ .temp_c	= 0.0, .ohm	= 32014 },
	{ .temp_c	= 5.0, .ohm	= 25011 },
	{ .temp_c	= 10.0, .ohm	= 19691 },
	{ .temp_c	= 15.0, .ohm	= 15618 },
	{ .temp_c	= 20.0, .ohm	= 12474 },
	{ .temp_c	= 25.0, .ohm	= 10000 },
	{ .temp_c	= 30.0, .ohm	= 8080 },
	{ .temp_c	= 35.0, .ohm	= 6569 },
	{ .temp_c	= 40.0, .ohm	= 5372 },
	{ .temp_c	= 45.0, .ohm	= 4424 },
	{ .temp_c	= 50.0, .ohm	= 3661 },
	{ .temp_c	= 55.0, .ohm	= 3039 },
	{ .temp_c	= 60.0, .ohm	= 2536 },
	{ .temp_c	= 65.0, .ohm	= 2128 },
	{ .temp_c	= 70.0, .ohm	= 1794 },
	{ .temp_c	= 75.0, .ohm	= 1518 },
	{ .temp_c	= 80.0, .ohm	= 1290 },
	{ .temp_c	= 85.0, .ohm	= 1100 },
	{ .temp_c	= 90.0, .ohm	= 942 },
	{ .temp_c	= 95.0, .ohm	= 809 },
	{ .temp_c	= 100.0, .ohm	= 697 },
	{ .temp_c	= 105.0, .ohm	= 604 },
	{ .temp_c	= 110.0, .ohm	= 525 },
	{ .temp_c	= 115.0, .ohm	= 457 },
	{ .temp_c	= 120.0, .ohm	= 400 },
	{ .temp_c	= 125.0, .ohm	= 351 },
	{ .temp_c	= 130.0, .ohm	= 308 },
	{ .temp_c	= 135.0, .ohm	= 272 },
	{ .temp_c	= 140.0, .ohm	= 240 },
	{ .temp_c	= 145.0, .ohm	= 213 },
	{ .temp_c	= 150.0, .ohm	= 189 },
	{ .temp_c	= 155.0, .ohm	= 168 },
};

struct ntc_type {
	const struct ntc_compensation *comp;
	int n_comp;
};

#define NTC_TYPE(ntc, compensation) \
[(ntc)] = { .comp = (compensation), .n_comp = ARRAY_SIZE(compensation) }

static const struct ntc_type ntc_type[] = {
	NTC_TYPE(TYPE_B57330V2103, b57330v2103),
	NTC_TYPE(TYPE_B57891S0103, b57891s0103),
	NTC_TYPE(TYPE_NCPXXWB473,  ncpXXwb473),
	NTC_TYPE(TYPE_NCPXXWF104,  ncpXXwf104),
	NTC_TYPE(TYPE_NCPXXWL333,  ncpXXwl333),
	NTC_TYPE(TYPE_NCPXXXH103,  ncpXXxh103),
};

struct ntc_data {
	struct ntc_thermistor_platform_data *pdata;
	const struct ntc_compensation *comp;
	int n_comp;
};

#if defined(CONFIG_OF) && IS_ENABLED(CONFIG_IIO)
static int ntc_adc_iio_read(struct ntc_thermistor_platform_data *pdata)
{
	struct iio_channel *channel = pdata->chan;
	int raw, uv, ret;

	ret = iio_read_channel_raw(channel, &raw);
	if (ret < 0) {
		pr_err("read channel() error: %d\n", ret);
		return ret;
	}

	ret = iio_convert_raw_to_processed(channel, raw, &uv, 1000);
	if (ret < 0) {
		/* Assume 12 bit ADC with vref at pullup_uv */
		uv = (pdata->pullup_uv * (s64)raw) >> 12;
	}

	return uv;
}

static const struct of_device_id ntc_match[] = {
	{ .compatible = "epcos,b57330v2103",
		.data = &ntc_thermistor_id[NTC_B57330V2103]},
	{ .compatible = "epcos,b57891s0103",
		.data = &ntc_thermistor_id[NTC_B57891S0103] },
	{ .compatible = "murata,ncp03wb473",
		.data = &ntc_thermistor_id[NTC_NCP03WB473] },
	{ .compatible = "murata,ncp03wf104",
		.data = &ntc_thermistor_id[NTC_NCP03WF104] },
	{ .compatible = "murata,ncp15wb473",
		.data = &ntc_thermistor_id[NTC_NCP15WB473] },
	{ .compatible = "murata,ncp15wl333",
		.data = &ntc_thermistor_id[NTC_NCP15WL333] },
	{ .compatible = "murata,ncp15xh103",
		.data = &ntc_thermistor_id[NTC_NCP15XH103] },
	{ .compatible = "murata,ncp18wb473",
		.data = &ntc_thermistor_id[NTC_NCP18WB473] },
	{ .compatible = "murata,ncp21wb473",
		.data = &ntc_thermistor_id[NTC_NCP21WB473] },

	/* Usage of vendor name "ntc" is deprecated */
	{ .compatible = "ntc,ncp03wb473",
		.data = &ntc_thermistor_id[NTC_NCP03WB473] },
	{ .compatible = "ntc,ncp15wb473",
		.data = &ntc_thermistor_id[NTC_NCP15WB473] },
	{ .compatible = "ntc,ncp15wl333",
		.data = &ntc_thermistor_id[NTC_NCP15WL333] },
	{ .compatible = "ntc,ncp18wb473",
		.data = &ntc_thermistor_id[NTC_NCP18WB473] },
	{ .compatible = "ntc,ncp21wb473",
		.data = &ntc_thermistor_id[NTC_NCP21WB473] },
	{ },
};
MODULE_DEVICE_TABLE(of, ntc_match);

static struct ntc_thermistor_platform_data *
ntc_thermistor_parse_dt(struct device *dev)
{
	struct iio_channel *chan;
	enum iio_chan_type type;
	struct device_node *np = dev->of_node;
	struct ntc_thermistor_platform_data *pdata;
	int ret;

	if (!np)
		return NULL;

	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
	if (!pdata)
		return ERR_PTR(-ENOMEM);

	chan = devm_iio_channel_get(dev, NULL);
	if (IS_ERR(chan))
		return ERR_CAST(chan);

	ret = iio_get_channel_type(chan, &type);
	if (ret < 0)
		return ERR_PTR(ret);

	if (type != IIO_VOLTAGE)
		return ERR_PTR(-EINVAL);

	if (of_property_read_u32(np, "pullup-uv", &pdata->pullup_uv))
		return ERR_PTR(-ENODEV);
	if (of_property_read_u32(np, "pullup-ohm", &pdata->pullup_ohm))
		return ERR_PTR(-ENODEV);
	if (of_property_read_u32(np, "pulldown-ohm", &pdata->pulldown_ohm))
		return ERR_PTR(-ENODEV);

	if (of_find_property(np, "connected-positive", NULL))
		pdata->connect = NTC_CONNECTED_POSITIVE;
	else /* status change should be possible if not always on. */
		pdata->connect = NTC_CONNECTED_GROUND;

	pdata->chan = chan;
	pdata->read_uv = ntc_adc_iio_read;

	return pdata;
}
#else
static struct ntc_thermistor_platform_data *
ntc_thermistor_parse_dt(struct device *dev)
{
	return NULL;
}

#define ntc_match	NULL

#endif

static inline u64 div64_u64_safe(u64 dividend, u64 divisor)
{
	if (divisor == 0 && dividend == 0)
		return 0;
	if (divisor == 0)
		return UINT_MAX;
	return div64_u64(dividend, divisor);
}

static int get_ohm_of_thermistor(struct ntc_data *data, unsigned int uv)
{
	struct ntc_thermistor_platform_data *pdata = data->pdata;
	u32 puv = pdata->pullup_uv;
	u64 n, puo, pdo;
	puo = pdata->pullup_ohm;
	pdo = pdata->pulldown_ohm;

	if (uv == 0)
		return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
			INT_MAX : 0;
	if (uv >= puv)
		return (pdata->connect == NTC_CONNECTED_POSITIVE) ?
			0 : INT_MAX;

	if (pdata->connect == NTC_CONNECTED_POSITIVE && puo == 0)
		n = div_u64(pdo * (puv - uv), uv);
	else if (pdata->connect == NTC_CONNECTED_GROUND && pdo == 0)
		n = div_u64(puo * uv, puv - uv);
	else if (pdata->connect == NTC_CONNECTED_POSITIVE)
		n = div64_u64_safe(pdo * puo * (puv - uv),
				puo * uv - pdo * (puv - uv));
	else
		n = div64_u64_safe(pdo * puo * uv, pdo * (puv - uv) - puo * uv);

	if (n > INT_MAX)
		n = INT_MAX;
	return n;
}

static void lookup_comp(struct ntc_data *data, unsigned int ohm,
			int *i_low, int *i_high)
{
	int start, end, mid;

	/*
	 * Handle special cases: Resistance is higher than or equal to
	 * resistance in first table entry, or resistance is lower or equal
	 * to resistance in last table entry.
	 * In these cases, return i_low == i_high, either pointing to the
	 * beginning or to the end of the table depending on the condition.
	 */
	if (ohm >= data->comp[0].ohm) {
		*i_low = 0;
		*i_high = 0;
		return;
	}
	if (ohm <= data->comp[data->n_comp - 1].ohm) {
		*i_low = data->n_comp - 1;
		*i_high = data->n_comp - 1;
		return;
	}

	/* Do a binary search on compensation table */
	start = 0;
	end = data->n_comp;
	while (start < end) {
		mid = start + (end - start) / 2;
		/*
		 * start <= mid < end
		 * data->comp[start].ohm > ohm >= data->comp[end].ohm
		 *
		 * We could check for "ohm == data->comp[mid].ohm" here, but
		 * that is a quite unlikely condition, and we would have to
		 * check again after updating start. Check it at the end instead
		 * for simplicity.
		 */
		if (ohm >= data->comp[mid].ohm) {
			end = mid;
		} else {
			start = mid + 1;
			/*
			 * ohm >= data->comp[start].ohm might be true here,
			 * since we set start to mid + 1. In that case, we are
			 * done. We could keep going, but the condition is quite
			 * likely to occur, so it is worth checking for it.
			 */
			if (ohm >= data->comp[start].ohm)
				end = start;
		}
		/*
		 * start <= end
		 * data->comp[start].ohm >= ohm >= data->comp[end].ohm
		 */
	}
	/*
	 * start == end
	 * ohm >= data->comp[end].ohm
	 */
	*i_low = end;
	if (ohm == data->comp[end].ohm)
		*i_high = end;
	else
		*i_high = end - 1;
}

static int get_temp_mc(struct ntc_data *data, unsigned int ohm)
{
	int low, high;
	int temp;

	lookup_comp(data, ohm, &low, &high);
	if (low == high) {
		/* Unable to use linear approximation */
		temp = data->comp[low].temp_c * 1000;
	} else {
		temp = data->comp[low].temp_c * 1000 +
			((data->comp[high].temp_c - data->comp[low].temp_c) *
			 1000 * ((int)ohm - (int)data->comp[low].ohm)) /
			((int)data->comp[high].ohm - (int)data->comp[low].ohm);
	}
	return temp;
}

static int ntc_thermistor_get_ohm(struct ntc_data *data)
{
	int read_uv;

	if (data->pdata->read_ohm)
		return data->pdata->read_ohm();

	if (data->pdata->read_uv) {
		read_uv = data->pdata->read_uv(data->pdata);
		if (read_uv < 0)
			return read_uv;
		return get_ohm_of_thermistor(data, read_uv);
	}
	return -EINVAL;
}

static int ntc_read(struct device *dev, enum hwmon_sensor_types type,
		    u32 attr, int channel, long *val)
{
	struct ntc_data *data = dev_get_drvdata(dev);
	int ohm;

	switch (type) {
	case hwmon_temp:
		switch (attr) {
		case hwmon_temp_input:
			ohm = ntc_thermistor_get_ohm(data);
			if (ohm < 0)
				return ohm;
			*val = get_temp_mc(data, ohm);
			return 0;
		case hwmon_temp_type:
			*val = 4;
			return 0;
		default:
			break;
		}
		break;
	default:
		break;
	}
	return -EINVAL;
}

static umode_t ntc_is_visible(const void *data, enum hwmon_sensor_types type,
			      u32 attr, int channel)
{
	if (type == hwmon_temp) {
		switch (attr) {
		case hwmon_temp_input:
		case hwmon_temp_type:
			return 0444;
		default:
			break;
		}
	}
	return 0;
}

static const u32 ntc_chip_config[] = {
	HWMON_C_REGISTER_TZ,
	0
};

static const struct hwmon_channel_info ntc_chip = {
	.type = hwmon_chip,
	.config = ntc_chip_config,
};

static const u32 ntc_temp_config[] = {
	HWMON_T_INPUT, HWMON_T_TYPE,
	0
};

static const struct hwmon_channel_info ntc_temp = {
	.type = hwmon_temp,
	.config = ntc_temp_config,
};

static const struct hwmon_channel_info *ntc_info[] = {
	&ntc_chip,
	&ntc_temp,
	NULL
};

static const struct hwmon_ops ntc_hwmon_ops = {
	.is_visible = ntc_is_visible,
	.read = ntc_read,
};

static const struct hwmon_chip_info ntc_chip_info = {
	.ops = &ntc_hwmon_ops,
	.info = ntc_info,
};

static int ntc_thermistor_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	const struct of_device_id *of_id =
			of_match_device(of_match_ptr(ntc_match), dev);
	const struct platform_device_id *pdev_id;
	struct ntc_thermistor_platform_data *pdata;
	struct device *hwmon_dev;
	struct ntc_data *data;

	pdata = ntc_thermistor_parse_dt(dev);
	if (IS_ERR(pdata))
		return PTR_ERR(pdata);
	else if (pdata == NULL)
		pdata = dev_get_platdata(dev);

	if (!pdata) {
		dev_err(dev, "No platform init data supplied.\n");
		return -ENODEV;
	}

	/* Either one of the two is required. */
	if (!pdata->read_uv && !pdata->read_ohm) {
		dev_err(dev,
			"Both read_uv and read_ohm missing. Need either one of the two.\n");
		return -EINVAL;
	}

	if (pdata->read_uv && pdata->read_ohm) {
		dev_warn(dev,
			 "Only one of read_uv and read_ohm is needed; ignoring read_uv.\n");
		pdata->read_uv = NULL;
	}

	if (pdata->read_uv && (pdata->pullup_uv == 0 ||
				(pdata->pullup_ohm == 0 && pdata->connect ==
				 NTC_CONNECTED_GROUND) ||
				(pdata->pulldown_ohm == 0 && pdata->connect ==
				 NTC_CONNECTED_POSITIVE) ||
				(pdata->connect != NTC_CONNECTED_POSITIVE &&
				 pdata->connect != NTC_CONNECTED_GROUND))) {
		dev_err(dev, "Required data to use read_uv not supplied.\n");
		return -EINVAL;
	}

	data = devm_kzalloc(dev, sizeof(struct ntc_data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	pdev_id = of_id ? of_id->data : platform_get_device_id(pdev);

	data->pdata = pdata;

	if (pdev_id->driver_data >= ARRAY_SIZE(ntc_type)) {
		dev_err(dev, "Unknown device type: %lu(%s)\n",
				pdev_id->driver_data, pdev_id->name);
		return -EINVAL;
	}

	data->comp   = ntc_type[pdev_id->driver_data].comp;
	data->n_comp = ntc_type[pdev_id->driver_data].n_comp;

	hwmon_dev = devm_hwmon_device_register_with_info(dev, pdev_id->name,
							 data, &ntc_chip_info,
							 NULL);
	if (IS_ERR(hwmon_dev)) {
		dev_err(dev, "unable to register as hwmon device.\n");
		return PTR_ERR(hwmon_dev);
	}

	dev_info(dev, "Thermistor type: %s successfully probed.\n",
		 pdev_id->name);

	return 0;
}

static struct platform_driver ntc_thermistor_driver = {
	.driver = {
		.name = "ntc-thermistor",
		.of_match_table = of_match_ptr(ntc_match),
	},
	.probe = ntc_thermistor_probe,
	.id_table = ntc_thermistor_id,
};

module_platform_driver(ntc_thermistor_driver);

MODULE_DESCRIPTION("NTC Thermistor Driver");
MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ntc-thermistor");