summaryrefslogtreecommitdiff
path: root/drivers/iio/temperature/ltc2983.c
blob: 55ff28a0f1c748f2c0194dfd61d005cc2d549f6c (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
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
// SPDX-License-Identifier: GPL-2.0
/*
 * Analog Devices LTC2983 Multi-Sensor Digital Temperature Measurement System
 * driver
 *
 * Copyright 2019 Analog Devices Inc.
 */
#include <linux/bitfield.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/iio/iio.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/of_gpio.h>
#include <linux/regmap.h>
#include <linux/spi/spi.h>

/* register map */
#define LTC2983_STATUS_REG			0x0000
#define LTC2983_TEMP_RES_START_REG		0x0010
#define LTC2983_TEMP_RES_END_REG		0x005F
#define LTC2983_GLOBAL_CONFIG_REG		0x00F0
#define LTC2983_MULT_CHANNEL_START_REG		0x00F4
#define LTC2983_MULT_CHANNEL_END_REG		0x00F7
#define LTC2983_MUX_CONFIG_REG			0x00FF
#define LTC2983_CHAN_ASSIGN_START_REG		0x0200
#define LTC2983_CHAN_ASSIGN_END_REG		0x024F
#define LTC2983_CUST_SENS_TBL_START_REG		0x0250
#define LTC2983_CUST_SENS_TBL_END_REG		0x03CF

#define LTC2983_DIFFERENTIAL_CHAN_MIN		2
#define LTC2983_MAX_CHANNELS_NR			20
#define LTC2983_MIN_CHANNELS_NR			1
#define LTC2983_SLEEP				0x97
#define LTC2983_CUSTOM_STEINHART_SIZE		24
#define LTC2983_CUSTOM_SENSOR_ENTRY_SZ		6
#define LTC2983_CUSTOM_STEINHART_ENTRY_SZ	4

#define LTC2983_CHAN_START_ADDR(chan) \
			(((chan - 1) * 4) + LTC2983_CHAN_ASSIGN_START_REG)
#define LTC2983_CHAN_RES_ADDR(chan) \
			(((chan - 1) * 4) + LTC2983_TEMP_RES_START_REG)
#define LTC2983_THERMOCOUPLE_DIFF_MASK		BIT(3)
#define LTC2983_THERMOCOUPLE_SGL(x) \
				FIELD_PREP(LTC2983_THERMOCOUPLE_DIFF_MASK, x)
#define LTC2983_THERMOCOUPLE_OC_CURR_MASK	GENMASK(1, 0)
#define LTC2983_THERMOCOUPLE_OC_CURR(x) \
				FIELD_PREP(LTC2983_THERMOCOUPLE_OC_CURR_MASK, x)
#define LTC2983_THERMOCOUPLE_OC_CHECK_MASK	BIT(2)
#define LTC2983_THERMOCOUPLE_OC_CHECK(x) \
			FIELD_PREP(LTC2983_THERMOCOUPLE_OC_CHECK_MASK, x)

#define LTC2983_THERMISTOR_DIFF_MASK		BIT(2)
#define LTC2983_THERMISTOR_SGL(x) \
				FIELD_PREP(LTC2983_THERMISTOR_DIFF_MASK, x)
#define LTC2983_THERMISTOR_R_SHARE_MASK		BIT(1)
#define LTC2983_THERMISTOR_R_SHARE(x) \
				FIELD_PREP(LTC2983_THERMISTOR_R_SHARE_MASK, x)
#define LTC2983_THERMISTOR_C_ROTATE_MASK	BIT(0)
#define LTC2983_THERMISTOR_C_ROTATE(x) \
				FIELD_PREP(LTC2983_THERMISTOR_C_ROTATE_MASK, x)

#define LTC2983_DIODE_DIFF_MASK			BIT(2)
#define LTC2983_DIODE_SGL(x) \
			FIELD_PREP(LTC2983_DIODE_DIFF_MASK, x)
#define LTC2983_DIODE_3_CONV_CYCLE_MASK		BIT(1)
#define LTC2983_DIODE_3_CONV_CYCLE(x) \
				FIELD_PREP(LTC2983_DIODE_3_CONV_CYCLE_MASK, x)
#define LTC2983_DIODE_AVERAGE_ON_MASK		BIT(0)
#define LTC2983_DIODE_AVERAGE_ON(x) \
				FIELD_PREP(LTC2983_DIODE_AVERAGE_ON_MASK, x)

#define LTC2983_RTD_4_WIRE_MASK			BIT(3)
#define LTC2983_RTD_ROTATION_MASK		BIT(1)
#define LTC2983_RTD_C_ROTATE(x) \
			FIELD_PREP(LTC2983_RTD_ROTATION_MASK, x)
#define LTC2983_RTD_KELVIN_R_SENSE_MASK		GENMASK(3, 2)
#define LTC2983_RTD_N_WIRES_MASK		GENMASK(3, 2)
#define LTC2983_RTD_N_WIRES(x) \
			FIELD_PREP(LTC2983_RTD_N_WIRES_MASK, x)
#define LTC2983_RTD_R_SHARE_MASK		BIT(0)
#define LTC2983_RTD_R_SHARE(x) \
			FIELD_PREP(LTC2983_RTD_R_SHARE_MASK, 1)

#define LTC2983_COMMON_HARD_FAULT_MASK	GENMASK(31, 30)
#define LTC2983_COMMON_SOFT_FAULT_MASK	GENMASK(27, 25)

#define	LTC2983_STATUS_START_MASK	BIT(7)
#define	LTC2983_STATUS_START(x)		FIELD_PREP(LTC2983_STATUS_START_MASK, x)

#define	LTC2983_STATUS_CHAN_SEL_MASK	GENMASK(4, 0)
#define	LTC2983_STATUS_CHAN_SEL(x) \
				FIELD_PREP(LTC2983_STATUS_CHAN_SEL_MASK, x)

#define LTC2983_TEMP_UNITS_MASK		BIT(2)
#define LTC2983_TEMP_UNITS(x)		FIELD_PREP(LTC2983_TEMP_UNITS_MASK, x)

#define LTC2983_NOTCH_FREQ_MASK		GENMASK(1, 0)
#define LTC2983_NOTCH_FREQ(x)		FIELD_PREP(LTC2983_NOTCH_FREQ_MASK, x)

#define LTC2983_RES_VALID_MASK		BIT(24)
#define LTC2983_DATA_MASK		GENMASK(23, 0)
#define LTC2983_DATA_SIGN_BIT		23

#define LTC2983_CHAN_TYPE_MASK		GENMASK(31, 27)
#define LTC2983_CHAN_TYPE(x)		FIELD_PREP(LTC2983_CHAN_TYPE_MASK, x)

/* cold junction for thermocouples and rsense for rtd's and thermistor's */
#define LTC2983_CHAN_ASSIGN_MASK	GENMASK(26, 22)
#define LTC2983_CHAN_ASSIGN(x)		FIELD_PREP(LTC2983_CHAN_ASSIGN_MASK, x)

#define LTC2983_CUSTOM_LEN_MASK		GENMASK(5, 0)
#define LTC2983_CUSTOM_LEN(x)		FIELD_PREP(LTC2983_CUSTOM_LEN_MASK, x)

#define LTC2983_CUSTOM_ADDR_MASK	GENMASK(11, 6)
#define LTC2983_CUSTOM_ADDR(x)		FIELD_PREP(LTC2983_CUSTOM_ADDR_MASK, x)

#define LTC2983_THERMOCOUPLE_CFG_MASK	GENMASK(21, 18)
#define LTC2983_THERMOCOUPLE_CFG(x) \
				FIELD_PREP(LTC2983_THERMOCOUPLE_CFG_MASK, x)
#define LTC2983_THERMOCOUPLE_HARD_FAULT_MASK	GENMASK(31, 29)
#define LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK	GENMASK(28, 25)

#define LTC2983_RTD_CFG_MASK		GENMASK(21, 18)
#define LTC2983_RTD_CFG(x)		FIELD_PREP(LTC2983_RTD_CFG_MASK, x)
#define LTC2983_RTD_EXC_CURRENT_MASK	GENMASK(17, 14)
#define LTC2983_RTD_EXC_CURRENT(x) \
				FIELD_PREP(LTC2983_RTD_EXC_CURRENT_MASK, x)
#define LTC2983_RTD_CURVE_MASK		GENMASK(13, 12)
#define LTC2983_RTD_CURVE(x)		FIELD_PREP(LTC2983_RTD_CURVE_MASK, x)

#define LTC2983_THERMISTOR_CFG_MASK	GENMASK(21, 19)
#define LTC2983_THERMISTOR_CFG(x) \
				FIELD_PREP(LTC2983_THERMISTOR_CFG_MASK, x)
#define LTC2983_THERMISTOR_EXC_CURRENT_MASK	GENMASK(18, 15)
#define LTC2983_THERMISTOR_EXC_CURRENT(x) \
			FIELD_PREP(LTC2983_THERMISTOR_EXC_CURRENT_MASK, x)

#define LTC2983_DIODE_CFG_MASK		GENMASK(26, 24)
#define LTC2983_DIODE_CFG(x)		FIELD_PREP(LTC2983_DIODE_CFG_MASK, x)
#define LTC2983_DIODE_EXC_CURRENT_MASK	GENMASK(23, 22)
#define LTC2983_DIODE_EXC_CURRENT(x) \
				FIELD_PREP(LTC2983_DIODE_EXC_CURRENT_MASK, x)
#define LTC2983_DIODE_IDEAL_FACTOR_MASK	GENMASK(21, 0)
#define LTC2983_DIODE_IDEAL_FACTOR(x) \
				FIELD_PREP(LTC2983_DIODE_IDEAL_FACTOR_MASK, x)

#define LTC2983_R_SENSE_VAL_MASK	GENMASK(26, 0)
#define LTC2983_R_SENSE_VAL(x)		FIELD_PREP(LTC2983_R_SENSE_VAL_MASK, x)

#define LTC2983_ADC_SINGLE_ENDED_MASK	BIT(26)
#define LTC2983_ADC_SINGLE_ENDED(x) \
				FIELD_PREP(LTC2983_ADC_SINGLE_ENDED_MASK, x)

enum {
	LTC2983_SENSOR_THERMOCOUPLE = 1,
	LTC2983_SENSOR_THERMOCOUPLE_CUSTOM = 9,
	LTC2983_SENSOR_RTD = 10,
	LTC2983_SENSOR_RTD_CUSTOM = 18,
	LTC2983_SENSOR_THERMISTOR = 19,
	LTC2983_SENSOR_THERMISTOR_STEINHART = 26,
	LTC2983_SENSOR_THERMISTOR_CUSTOM = 27,
	LTC2983_SENSOR_DIODE = 28,
	LTC2983_SENSOR_SENSE_RESISTOR = 29,
	LTC2983_SENSOR_DIRECT_ADC = 30,
};

#define to_thermocouple(_sensor) \
		container_of(_sensor, struct ltc2983_thermocouple, sensor)

#define to_rtd(_sensor) \
		container_of(_sensor, struct ltc2983_rtd, sensor)

#define to_thermistor(_sensor) \
		container_of(_sensor, struct ltc2983_thermistor, sensor)

#define to_diode(_sensor) \
		container_of(_sensor, struct ltc2983_diode, sensor)

#define to_rsense(_sensor) \
		container_of(_sensor, struct ltc2983_rsense, sensor)

#define to_adc(_sensor) \
		container_of(_sensor, struct ltc2983_adc, sensor)

struct ltc2983_data {
	struct regmap *regmap;
	struct spi_device *spi;
	struct mutex lock;
	struct completion completion;
	struct iio_chan_spec *iio_chan;
	struct ltc2983_sensor **sensors;
	u32 mux_delay_config;
	u32 filter_notch_freq;
	u16 custom_table_size;
	u8 num_channels;
	u8 iio_channels;
	/*
	 * DMA (thus cache coherency maintenance) requires the
	 * transfer buffers to live in their own cache lines.
	 * Holds the converted temperature
	 */
	__be32 temp ____cacheline_aligned;
};

struct ltc2983_sensor {
	int (*fault_handler)(const struct ltc2983_data *st, const u32 result);
	int (*assign_chan)(struct ltc2983_data *st,
			   const struct ltc2983_sensor *sensor);
	/* specifies the sensor channel */
	u32 chan;
	/* sensor type */
	u32 type;
};

struct ltc2983_custom_sensor {
	/* raw table sensor data */
	u8 *table;
	size_t size;
	/* address offset */
	s8 offset;
	bool is_steinhart;
};

struct ltc2983_thermocouple {
	struct ltc2983_sensor sensor;
	struct ltc2983_custom_sensor *custom;
	u32 sensor_config;
	u32 cold_junction_chan;
};

struct ltc2983_rtd {
	struct ltc2983_sensor sensor;
	struct ltc2983_custom_sensor *custom;
	u32 sensor_config;
	u32 r_sense_chan;
	u32 excitation_current;
	u32 rtd_curve;
};

struct ltc2983_thermistor {
	struct ltc2983_sensor sensor;
	struct ltc2983_custom_sensor *custom;
	u32 sensor_config;
	u32 r_sense_chan;
	u32 excitation_current;
};

struct ltc2983_diode {
	struct ltc2983_sensor sensor;
	u32 sensor_config;
	u32 excitation_current;
	u32 ideal_factor_value;
};

struct ltc2983_rsense {
	struct ltc2983_sensor sensor;
	u32 r_sense_val;
};

struct ltc2983_adc {
	struct ltc2983_sensor sensor;
	bool single_ended;
};

/*
 * Convert to Q format numbers. These number's are integers where
 * the number of integer and fractional bits are specified. The resolution
 * is given by 1/@resolution and tell us the number of fractional bits. For
 * instance a resolution of 2^-10 means we have 10 fractional bits.
 */
static u32 __convert_to_raw(const u64 val, const u32 resolution)
{
	u64 __res = val * resolution;

	/* all values are multiplied by 1000000 to remove the fraction */
	do_div(__res, 1000000);

	return __res;
}

static u32 __convert_to_raw_sign(const u64 val, const u32 resolution)
{
	s64 __res = -(s32)val;

	__res = __convert_to_raw(__res, resolution);

	return (u32)-__res;
}

static int __ltc2983_fault_handler(const struct ltc2983_data *st,
				   const u32 result, const u32 hard_mask,
				   const u32 soft_mask)
{
	const struct device *dev = &st->spi->dev;

	if (result & hard_mask) {
		dev_err(dev, "Invalid conversion: Sensor HARD fault\n");
		return -EIO;
	} else if (result & soft_mask) {
		/* just print a warning */
		dev_warn(dev, "Suspicious conversion: Sensor SOFT fault\n");
	}

	return 0;
}

static int __ltc2983_chan_assign_common(const struct ltc2983_data *st,
					const struct ltc2983_sensor *sensor,
					u32 chan_val)
{
	u32 reg = LTC2983_CHAN_START_ADDR(sensor->chan);
	__be32 __chan_val;

	chan_val |= LTC2983_CHAN_TYPE(sensor->type);
	dev_dbg(&st->spi->dev, "Assign reg:0x%04X, val:0x%08X\n", reg,
		chan_val);
	__chan_val = cpu_to_be32(chan_val);
	return regmap_bulk_write(st->regmap, reg, &__chan_val,
				 sizeof(__chan_val));
}

static int __ltc2983_chan_custom_sensor_assign(struct ltc2983_data *st,
					  struct ltc2983_custom_sensor *custom,
					  u32 *chan_val)
{
	u32 reg;
	u8 mult = custom->is_steinhart ? LTC2983_CUSTOM_STEINHART_ENTRY_SZ :
		LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
	const struct device *dev = &st->spi->dev;
	/*
	 * custom->size holds the raw size of the table. However, when
	 * configuring the sensor channel, we must write the number of
	 * entries of the table minus 1. For steinhart sensors 0 is written
	 * since the size is constant!
	 */
	const u8 len = custom->is_steinhart ? 0 :
		(custom->size / LTC2983_CUSTOM_SENSOR_ENTRY_SZ) - 1;
	/*
	 * Check if the offset was assigned already. It should be for steinhart
	 * sensors. When coming from sleep, it should be assigned for all.
	 */
	if (custom->offset < 0) {
		/*
		 * This needs to be done again here because, from the moment
		 * when this test was done (successfully) for this custom
		 * sensor, a steinhart sensor might have been added changing
		 * custom_table_size...
		 */
		if (st->custom_table_size + custom->size >
		    (LTC2983_CUST_SENS_TBL_END_REG -
		     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
			dev_err(dev,
				"Not space left(%d) for new custom sensor(%zu)",
				st->custom_table_size,
				custom->size);
			return -EINVAL;
		}

		custom->offset = st->custom_table_size /
					LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
		st->custom_table_size += custom->size;
	}

	reg = (custom->offset * mult) + LTC2983_CUST_SENS_TBL_START_REG;

	*chan_val |= LTC2983_CUSTOM_LEN(len);
	*chan_val |= LTC2983_CUSTOM_ADDR(custom->offset);
	dev_dbg(dev, "Assign custom sensor, reg:0x%04X, off:%d, sz:%zu",
		reg, custom->offset,
		custom->size);
	/* write custom sensor table */
	return regmap_bulk_write(st->regmap, reg, custom->table, custom->size);
}

static struct ltc2983_custom_sensor *__ltc2983_custom_sensor_new(
						struct ltc2983_data *st,
						const struct device_node *np,
						const char *propname,
						const bool is_steinhart,
						const u32 resolution,
						const bool has_signed)
{
	struct ltc2983_custom_sensor *new_custom;
	u8 index, n_entries, tbl = 0;
	struct device *dev = &st->spi->dev;
	/*
	 * For custom steinhart, the full u32 is taken. For all the others
	 * the MSB is discarded.
	 */
	const u8 n_size = is_steinhart ? 4 : 3;
	const u8 e_size = is_steinhart ? sizeof(u32) : sizeof(u64);

	n_entries = of_property_count_elems_of_size(np, propname, e_size);
	/* n_entries must be an even number */
	if (!n_entries || (n_entries % 2) != 0) {
		dev_err(dev, "Number of entries either 0 or not even\n");
		return ERR_PTR(-EINVAL);
	}

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

	new_custom->size = n_entries * n_size;
	/* check Steinhart size */
	if (is_steinhart && new_custom->size != LTC2983_CUSTOM_STEINHART_SIZE) {
		dev_err(dev, "Steinhart sensors size(%zu) must be 24",
							new_custom->size);
		return ERR_PTR(-EINVAL);
	}
	/* Check space on the table. */
	if (st->custom_table_size + new_custom->size >
	    (LTC2983_CUST_SENS_TBL_END_REG -
	     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
		dev_err(dev, "No space left(%d) for new custom sensor(%zu)",
				st->custom_table_size, new_custom->size);
		return ERR_PTR(-EINVAL);
	}

	/* allocate the table */
	new_custom->table = devm_kzalloc(dev, new_custom->size, GFP_KERNEL);
	if (!new_custom->table)
		return ERR_PTR(-ENOMEM);

	for (index = 0; index < n_entries; index++) {
		u64 temp = 0, j;
		/*
		 * Steinhart sensors are configured with raw values in the
		 * devicetree. For the other sensors we must convert the
		 * value to raw. The odd index's correspond to temperarures
		 * and always have 1/1024 of resolution. Temperatures also
		 * come in kelvin, so signed values is not possible
		 */
		if (!is_steinhart) {
			of_property_read_u64_index(np, propname, index, &temp);

			if ((index % 2) != 0)
				temp = __convert_to_raw(temp, 1024);
			else if (has_signed && (s64)temp < 0)
				temp = __convert_to_raw_sign(temp, resolution);
			else
				temp = __convert_to_raw(temp, resolution);
		} else {
			u32 t32;

			of_property_read_u32_index(np, propname, index, &t32);
			temp = t32;
		}

		for (j = 0; j < n_size; j++)
			new_custom->table[tbl++] =
				temp >> (8 * (n_size - j - 1));
	}

	new_custom->is_steinhart = is_steinhart;
	/*
	 * This is done to first add all the steinhart sensors to the table,
	 * in order to maximize the table usage. If we mix adding steinhart
	 * with the other sensors, we might have to do some roundup to make
	 * sure that sensor_addr - 0x250(start address) is a multiple of 4
	 * (for steinhart), and a multiple of 6 for all the other sensors.
	 * Since we have const 24 bytes for steinhart sensors and 24 is
	 * also a multiple of 6, we guarantee that the first non-steinhart
	 * sensor will sit in a correct address without the need of filling
	 * addresses.
	 */
	if (is_steinhart) {
		new_custom->offset = st->custom_table_size /
					LTC2983_CUSTOM_STEINHART_ENTRY_SZ;
		st->custom_table_size += new_custom->size;
	} else {
		/* mark as unset. This is checked later on the assign phase */
		new_custom->offset = -1;
	}

	return new_custom;
}

static int ltc2983_thermocouple_fault_handler(const struct ltc2983_data *st,
					      const u32 result)
{
	return __ltc2983_fault_handler(st, result,
				       LTC2983_THERMOCOUPLE_HARD_FAULT_MASK,
				       LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK);
}

static int ltc2983_common_fault_handler(const struct ltc2983_data *st,
					const u32 result)
{
	return __ltc2983_fault_handler(st, result,
				       LTC2983_COMMON_HARD_FAULT_MASK,
				       LTC2983_COMMON_SOFT_FAULT_MASK);
}

static int ltc2983_thermocouple_assign_chan(struct ltc2983_data *st,
				const struct ltc2983_sensor *sensor)
{
	struct ltc2983_thermocouple *thermo = to_thermocouple(sensor);
	u32 chan_val;

	chan_val = LTC2983_CHAN_ASSIGN(thermo->cold_junction_chan);
	chan_val |= LTC2983_THERMOCOUPLE_CFG(thermo->sensor_config);

	if (thermo->custom) {
		int ret;

		ret = __ltc2983_chan_custom_sensor_assign(st, thermo->custom,
							  &chan_val);
		if (ret)
			return ret;
	}
	return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static int ltc2983_rtd_assign_chan(struct ltc2983_data *st,
				   const struct ltc2983_sensor *sensor)
{
	struct ltc2983_rtd *rtd = to_rtd(sensor);
	u32 chan_val;

	chan_val = LTC2983_CHAN_ASSIGN(rtd->r_sense_chan);
	chan_val |= LTC2983_RTD_CFG(rtd->sensor_config);
	chan_val |= LTC2983_RTD_EXC_CURRENT(rtd->excitation_current);
	chan_val |= LTC2983_RTD_CURVE(rtd->rtd_curve);

	if (rtd->custom) {
		int ret;

		ret = __ltc2983_chan_custom_sensor_assign(st, rtd->custom,
							  &chan_val);
		if (ret)
			return ret;
	}
	return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static int ltc2983_thermistor_assign_chan(struct ltc2983_data *st,
					  const struct ltc2983_sensor *sensor)
{
	struct ltc2983_thermistor *thermistor = to_thermistor(sensor);
	u32 chan_val;

	chan_val = LTC2983_CHAN_ASSIGN(thermistor->r_sense_chan);
	chan_val |= LTC2983_THERMISTOR_CFG(thermistor->sensor_config);
	chan_val |=
		LTC2983_THERMISTOR_EXC_CURRENT(thermistor->excitation_current);

	if (thermistor->custom) {
		int ret;

		ret = __ltc2983_chan_custom_sensor_assign(st,
							  thermistor->custom,
							  &chan_val);
		if (ret)
			return ret;
	}
	return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static int ltc2983_diode_assign_chan(struct ltc2983_data *st,
				     const struct ltc2983_sensor *sensor)
{
	struct ltc2983_diode *diode = to_diode(sensor);
	u32 chan_val;

	chan_val = LTC2983_DIODE_CFG(diode->sensor_config);
	chan_val |= LTC2983_DIODE_EXC_CURRENT(diode->excitation_current);
	chan_val |= LTC2983_DIODE_IDEAL_FACTOR(diode->ideal_factor_value);

	return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static int ltc2983_r_sense_assign_chan(struct ltc2983_data *st,
				       const struct ltc2983_sensor *sensor)
{
	struct ltc2983_rsense *rsense = to_rsense(sensor);
	u32 chan_val;

	chan_val = LTC2983_R_SENSE_VAL(rsense->r_sense_val);

	return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static int ltc2983_adc_assign_chan(struct ltc2983_data *st,
				   const struct ltc2983_sensor *sensor)
{
	struct ltc2983_adc *adc = to_adc(sensor);
	u32 chan_val;

	chan_val = LTC2983_ADC_SINGLE_ENDED(adc->single_ended);

	return __ltc2983_chan_assign_common(st, sensor, chan_val);
}

static struct ltc2983_sensor *ltc2983_thermocouple_new(
					const struct device_node *child,
					struct ltc2983_data *st,
					const struct ltc2983_sensor *sensor)
{
	struct ltc2983_thermocouple *thermo;
	struct device_node *phandle;
	u32 oc_current;
	int ret;

	thermo = devm_kzalloc(&st->spi->dev, sizeof(*thermo), GFP_KERNEL);
	if (!thermo)
		return ERR_PTR(-ENOMEM);

	if (of_property_read_bool(child, "adi,single-ended"))
		thermo->sensor_config = LTC2983_THERMOCOUPLE_SGL(1);

	ret = of_property_read_u32(child, "adi,sensor-oc-current-microamp",
				   &oc_current);
	if (!ret) {
		switch (oc_current) {
		case 10:
			thermo->sensor_config |=
					LTC2983_THERMOCOUPLE_OC_CURR(0);
			break;
		case 100:
			thermo->sensor_config |=
					LTC2983_THERMOCOUPLE_OC_CURR(1);
			break;
		case 500:
			thermo->sensor_config |=
					LTC2983_THERMOCOUPLE_OC_CURR(2);
			break;
		case 1000:
			thermo->sensor_config |=
					LTC2983_THERMOCOUPLE_OC_CURR(3);
			break;
		default:
			dev_err(&st->spi->dev,
				"Invalid open circuit current:%u", oc_current);
			return ERR_PTR(-EINVAL);
		}

		thermo->sensor_config |= LTC2983_THERMOCOUPLE_OC_CHECK(1);
	}
	/* validate channel index */
	if (!(thermo->sensor_config & LTC2983_THERMOCOUPLE_DIFF_MASK) &&
	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
		dev_err(&st->spi->dev,
			"Invalid chann:%d for differential thermocouple",
			sensor->chan);
		return ERR_PTR(-EINVAL);
	}

	phandle = of_parse_phandle(child, "adi,cold-junction-handle", 0);
	if (phandle) {
		int ret;

		ret = of_property_read_u32(phandle, "reg",
					   &thermo->cold_junction_chan);
		if (ret) {
			/*
			 * This would be catched later but we can just return
			 * the error right away.
			 */
			dev_err(&st->spi->dev, "Property reg must be given\n");
			of_node_put(phandle);
			return ERR_PTR(-EINVAL);
		}
	}

	/* check custom sensor */
	if (sensor->type == LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
		const char *propname = "adi,custom-thermocouple";

		thermo->custom = __ltc2983_custom_sensor_new(st, child,
							     propname, false,
							     16384, true);
		if (IS_ERR(thermo->custom)) {
			of_node_put(phandle);
			return ERR_CAST(thermo->custom);
		}
	}

	/* set common parameters */
	thermo->sensor.fault_handler = ltc2983_thermocouple_fault_handler;
	thermo->sensor.assign_chan = ltc2983_thermocouple_assign_chan;

	of_node_put(phandle);
	return &thermo->sensor;
}

static struct ltc2983_sensor *ltc2983_rtd_new(const struct device_node *child,
					  struct ltc2983_data *st,
					  const struct ltc2983_sensor *sensor)
{
	struct ltc2983_rtd *rtd;
	int ret = 0;
	struct device *dev = &st->spi->dev;
	struct device_node *phandle;
	u32 excitation_current = 0, n_wires = 0;

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

	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
	if (!phandle) {
		dev_err(dev, "Property adi,rsense-handle missing or invalid");
		return ERR_PTR(-EINVAL);
	}

	ret = of_property_read_u32(phandle, "reg", &rtd->r_sense_chan);
	if (ret) {
		dev_err(dev, "Property reg must be given\n");
		goto fail;
	}

	ret = of_property_read_u32(child, "adi,number-of-wires", &n_wires);
	if (!ret) {
		switch (n_wires) {
		case 2:
			rtd->sensor_config = LTC2983_RTD_N_WIRES(0);
			break;
		case 3:
			rtd->sensor_config = LTC2983_RTD_N_WIRES(1);
			break;
		case 4:
			rtd->sensor_config = LTC2983_RTD_N_WIRES(2);
			break;
		case 5:
			/* 4 wires, Kelvin Rsense */
			rtd->sensor_config = LTC2983_RTD_N_WIRES(3);
			break;
		default:
			dev_err(dev, "Invalid number of wires:%u\n", n_wires);
			ret = -EINVAL;
			goto fail;
		}
	}

	if (of_property_read_bool(child, "adi,rsense-share")) {
		/* Current rotation is only available with rsense sharing */
		if (of_property_read_bool(child, "adi,current-rotate")) {
			if (n_wires == 2 || n_wires == 3) {
				dev_err(dev,
					"Rotation not allowed for 2/3 Wire RTDs");
				ret = -EINVAL;
				goto fail;
			}
			rtd->sensor_config |= LTC2983_RTD_C_ROTATE(1);
		} else {
			rtd->sensor_config |= LTC2983_RTD_R_SHARE(1);
		}
	}
	/*
	 * rtd channel indexes are a bit more complicated to validate.
	 * For 4wire RTD with rotation, the channel selection cannot be
	 * >=19 since the chann + 1 is used in this configuration.
	 * For 4wire RTDs with kelvin rsense, the rsense channel cannot be
	 * <=1 since chanel - 1 and channel - 2 are used.
	 */
	if (rtd->sensor_config & LTC2983_RTD_4_WIRE_MASK) {
		/* 4-wire */
		u8 min = LTC2983_DIFFERENTIAL_CHAN_MIN,
			max = LTC2983_MAX_CHANNELS_NR;

		if (rtd->sensor_config & LTC2983_RTD_ROTATION_MASK)
			max = LTC2983_MAX_CHANNELS_NR - 1;

		if (((rtd->sensor_config & LTC2983_RTD_KELVIN_R_SENSE_MASK)
		     == LTC2983_RTD_KELVIN_R_SENSE_MASK) &&
		    (rtd->r_sense_chan <=  min)) {
			/* kelvin rsense*/
			dev_err(dev,
				"Invalid rsense chann:%d to use in kelvin rsense",
				rtd->r_sense_chan);

			ret = -EINVAL;
			goto fail;
		}

		if (sensor->chan < min || sensor->chan > max) {
			dev_err(dev, "Invalid chann:%d for the rtd config",
				sensor->chan);

			ret = -EINVAL;
			goto fail;
		}
	} else {
		/* same as differential case */
		if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
			dev_err(&st->spi->dev,
				"Invalid chann:%d for RTD", sensor->chan);

			ret = -EINVAL;
			goto fail;
		}
	}

	/* check custom sensor */
	if (sensor->type == LTC2983_SENSOR_RTD_CUSTOM) {
		rtd->custom = __ltc2983_custom_sensor_new(st, child,
							  "adi,custom-rtd",
							  false, 2048, false);
		if (IS_ERR(rtd->custom)) {
			of_node_put(phandle);
			return ERR_CAST(rtd->custom);
		}
	}

	/* set common parameters */
	rtd->sensor.fault_handler = ltc2983_common_fault_handler;
	rtd->sensor.assign_chan = ltc2983_rtd_assign_chan;

	ret = of_property_read_u32(child, "adi,excitation-current-microamp",
				   &excitation_current);
	if (ret) {
		/* default to 5uA */
		rtd->excitation_current = 1;
	} else {
		switch (excitation_current) {
		case 5:
			rtd->excitation_current = 0x01;
			break;
		case 10:
			rtd->excitation_current = 0x02;
			break;
		case 25:
			rtd->excitation_current = 0x03;
			break;
		case 50:
			rtd->excitation_current = 0x04;
			break;
		case 100:
			rtd->excitation_current = 0x05;
			break;
		case 250:
			rtd->excitation_current = 0x06;
			break;
		case 500:
			rtd->excitation_current = 0x07;
			break;
		case 1000:
			rtd->excitation_current = 0x08;
			break;
		default:
			dev_err(&st->spi->dev,
				"Invalid value for excitation current(%u)",
				excitation_current);
			ret = -EINVAL;
			goto fail;
		}
	}

	of_property_read_u32(child, "adi,rtd-curve", &rtd->rtd_curve);

	of_node_put(phandle);
	return &rtd->sensor;
fail:
	of_node_put(phandle);
	return ERR_PTR(ret);
}

static struct ltc2983_sensor *ltc2983_thermistor_new(
					const struct device_node *child,
					struct ltc2983_data *st,
					const struct ltc2983_sensor *sensor)
{
	struct ltc2983_thermistor *thermistor;
	struct device *dev = &st->spi->dev;
	struct device_node *phandle;
	u32 excitation_current = 0;
	int ret = 0;

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

	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
	if (!phandle) {
		dev_err(dev, "Property adi,rsense-handle missing or invalid");
		return ERR_PTR(-EINVAL);
	}

	ret = of_property_read_u32(phandle, "reg", &thermistor->r_sense_chan);
	if (ret) {
		dev_err(dev, "rsense channel must be configured...\n");
		goto fail;
	}

	if (of_property_read_bool(child, "adi,single-ended")) {
		thermistor->sensor_config = LTC2983_THERMISTOR_SGL(1);
	} else if (of_property_read_bool(child, "adi,rsense-share")) {
		/* rotation is only possible if sharing rsense */
		if (of_property_read_bool(child, "adi,current-rotate"))
			thermistor->sensor_config =
						LTC2983_THERMISTOR_C_ROTATE(1);
		else
			thermistor->sensor_config =
						LTC2983_THERMISTOR_R_SHARE(1);
	}
	/* validate channel index */
	if (!(thermistor->sensor_config & LTC2983_THERMISTOR_DIFF_MASK) &&
	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
		dev_err(&st->spi->dev,
			"Invalid chann:%d for differential thermistor",
			sensor->chan);
		ret = -EINVAL;
		goto fail;
	}

	/* check custom sensor */
	if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART) {
		bool steinhart = false;
		const char *propname;

		if (sensor->type == LTC2983_SENSOR_THERMISTOR_STEINHART) {
			steinhart = true;
			propname = "adi,custom-steinhart";
		} else {
			propname = "adi,custom-thermistor";
		}

		thermistor->custom = __ltc2983_custom_sensor_new(st, child,
								 propname,
								 steinhart,
								 64, false);
		if (IS_ERR(thermistor->custom)) {
			of_node_put(phandle);
			return ERR_CAST(thermistor->custom);
		}
	}
	/* set common parameters */
	thermistor->sensor.fault_handler = ltc2983_common_fault_handler;
	thermistor->sensor.assign_chan = ltc2983_thermistor_assign_chan;

	ret = of_property_read_u32(child, "adi,excitation-current-nanoamp",
				   &excitation_current);
	if (ret) {
		/* Auto range is not allowed for custom sensors */
		if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART)
			/* default to 1uA */
			thermistor->excitation_current = 0x03;
		else
			/* default to auto-range */
			thermistor->excitation_current = 0x0c;
	} else {
		switch (excitation_current) {
		case 0:
			/* auto range */
			if (sensor->type >=
			    LTC2983_SENSOR_THERMISTOR_STEINHART) {
				dev_err(&st->spi->dev,
					"Auto Range not allowed for custom sensors\n");
				ret = -EINVAL;
				goto fail;
			}
			thermistor->excitation_current = 0x0c;
			break;
		case 250:
			thermistor->excitation_current = 0x01;
			break;
		case 500:
			thermistor->excitation_current = 0x02;
			break;
		case 1000:
			thermistor->excitation_current = 0x03;
			break;
		case 5000:
			thermistor->excitation_current = 0x04;
			break;
		case 10000:
			thermistor->excitation_current = 0x05;
			break;
		case 25000:
			thermistor->excitation_current = 0x06;
			break;
		case 50000:
			thermistor->excitation_current = 0x07;
			break;
		case 100000:
			thermistor->excitation_current = 0x08;
			break;
		case 250000:
			thermistor->excitation_current = 0x09;
			break;
		case 500000:
			thermistor->excitation_current = 0x0a;
			break;
		case 1000000:
			thermistor->excitation_current = 0x0b;
			break;
		default:
			dev_err(&st->spi->dev,
				"Invalid value for excitation current(%u)",
				excitation_current);
			ret = -EINVAL;
			goto fail;
		}
	}

	of_node_put(phandle);
	return &thermistor->sensor;
fail:
	of_node_put(phandle);
	return ERR_PTR(ret);
}

static struct ltc2983_sensor *ltc2983_diode_new(
					const struct device_node *child,
					const struct ltc2983_data *st,
					const struct ltc2983_sensor *sensor)
{
	struct ltc2983_diode *diode;
	u32 temp = 0, excitation_current = 0;
	int ret;

	diode = devm_kzalloc(&st->spi->dev, sizeof(*diode), GFP_KERNEL);
	if (!diode)
		return ERR_PTR(-ENOMEM);

	if (of_property_read_bool(child, "adi,single-ended"))
		diode->sensor_config = LTC2983_DIODE_SGL(1);

	if (of_property_read_bool(child, "adi,three-conversion-cycles"))
		diode->sensor_config |= LTC2983_DIODE_3_CONV_CYCLE(1);

	if (of_property_read_bool(child, "adi,average-on"))
		diode->sensor_config |= LTC2983_DIODE_AVERAGE_ON(1);

	/* validate channel index */
	if (!(diode->sensor_config & LTC2983_DIODE_DIFF_MASK) &&
	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
		dev_err(&st->spi->dev,
			"Invalid chann:%d for differential thermistor",
			sensor->chan);
		return ERR_PTR(-EINVAL);
	}
	/* set common parameters */
	diode->sensor.fault_handler = ltc2983_common_fault_handler;
	diode->sensor.assign_chan = ltc2983_diode_assign_chan;

	ret = of_property_read_u32(child, "adi,excitation-current-microamp",
				   &excitation_current);
	if (!ret) {
		switch (excitation_current) {
		case 10:
			diode->excitation_current = 0x00;
			break;
		case 20:
			diode->excitation_current = 0x01;
			break;
		case 40:
			diode->excitation_current = 0x02;
			break;
		case 80:
			diode->excitation_current = 0x03;
			break;
		default:
			dev_err(&st->spi->dev,
				"Invalid value for excitation current(%u)",
				excitation_current);
			return ERR_PTR(-EINVAL);
		}
	}

	of_property_read_u32(child, "adi,ideal-factor-value", &temp);

	/* 2^20 resolution */
	diode->ideal_factor_value = __convert_to_raw(temp, 1048576);

	return &diode->sensor;
}

static struct ltc2983_sensor *ltc2983_r_sense_new(struct device_node *child,
					struct ltc2983_data *st,
					const struct ltc2983_sensor *sensor)
{
	struct ltc2983_rsense *rsense;
	int ret;
	u32 temp;

	rsense = devm_kzalloc(&st->spi->dev, sizeof(*rsense), GFP_KERNEL);
	if (!rsense)
		return ERR_PTR(-ENOMEM);

	/* validate channel index */
	if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
		dev_err(&st->spi->dev, "Invalid chann:%d for r_sense",
			sensor->chan);
		return ERR_PTR(-EINVAL);
	}

	ret = of_property_read_u32(child, "adi,rsense-val-milli-ohms", &temp);
	if (ret) {
		dev_err(&st->spi->dev, "Property adi,rsense-val-milli-ohms missing\n");
		return ERR_PTR(-EINVAL);
	}
	/*
	 * Times 1000 because we have milli-ohms and __convert_to_raw
	 * expects scales of 1000000 which are used for all other
	 * properties.
	 * 2^10 resolution
	 */
	rsense->r_sense_val = __convert_to_raw((u64)temp * 1000, 1024);

	/* set common parameters */
	rsense->sensor.assign_chan = ltc2983_r_sense_assign_chan;

	return &rsense->sensor;
}

static struct ltc2983_sensor *ltc2983_adc_new(struct device_node *child,
					 struct ltc2983_data *st,
					 const struct ltc2983_sensor *sensor)
{
	struct ltc2983_adc *adc;

	adc = devm_kzalloc(&st->spi->dev, sizeof(*adc), GFP_KERNEL);
	if (!adc)
		return ERR_PTR(-ENOMEM);

	if (of_property_read_bool(child, "adi,single-ended"))
		adc->single_ended = true;

	if (!adc->single_ended &&
	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
		dev_err(&st->spi->dev, "Invalid chan:%d for differential adc\n",
			sensor->chan);
		return ERR_PTR(-EINVAL);
	}
	/* set common parameters */
	adc->sensor.assign_chan = ltc2983_adc_assign_chan;
	adc->sensor.fault_handler = ltc2983_common_fault_handler;

	return &adc->sensor;
}

static int ltc2983_chan_read(struct ltc2983_data *st,
			const struct ltc2983_sensor *sensor, int *val)
{
	u32 start_conversion = 0;
	int ret;
	unsigned long time;

	start_conversion = LTC2983_STATUS_START(true);
	start_conversion |= LTC2983_STATUS_CHAN_SEL(sensor->chan);
	dev_dbg(&st->spi->dev, "Start conversion on chan:%d, status:%02X\n",
		sensor->chan, start_conversion);
	/* start conversion */
	ret = regmap_write(st->regmap, LTC2983_STATUS_REG, start_conversion);
	if (ret)
		return ret;

	reinit_completion(&st->completion);
	/*
	 * wait for conversion to complete.
	 * 300 ms should be more than enough to complete the conversion.
	 * Depending on the sensor configuration, there are 2/3 conversions
	 * cycles of 82ms.
	 */
	time = wait_for_completion_timeout(&st->completion,
					   msecs_to_jiffies(300));
	if (!time) {
		dev_warn(&st->spi->dev, "Conversion timed out\n");
		return -ETIMEDOUT;
	}

	/* read the converted data */
	ret = regmap_bulk_read(st->regmap, LTC2983_CHAN_RES_ADDR(sensor->chan),
			       &st->temp, sizeof(st->temp));
	if (ret)
		return ret;

	*val = __be32_to_cpu(st->temp);

	if (!(LTC2983_RES_VALID_MASK & *val)) {
		dev_err(&st->spi->dev, "Invalid conversion detected\n");
		return -EIO;
	}

	ret = sensor->fault_handler(st, *val);
	if (ret)
		return ret;

	*val = sign_extend32((*val) & LTC2983_DATA_MASK, LTC2983_DATA_SIGN_BIT);
	return 0;
}

static int ltc2983_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val, int *val2, long mask)
{
	struct ltc2983_data *st = iio_priv(indio_dev);
	int ret;

	/* sanity check */
	if (chan->address >= st->num_channels) {
		dev_err(&st->spi->dev, "Invalid chan address:%ld",
			chan->address);
		return -EINVAL;
	}

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		mutex_lock(&st->lock);
		ret = ltc2983_chan_read(st, st->sensors[chan->address], val);
		mutex_unlock(&st->lock);
		return ret ?: IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		switch (chan->type) {
		case IIO_TEMP:
			/* value in milli degrees */
			*val = 1000;
			/* 2^10 */
			*val2 = 1024;
			return IIO_VAL_FRACTIONAL;
		case IIO_VOLTAGE:
			/* value in millivolt */
			*val = 1000;
			/* 2^21 */
			*val2 = 2097152;
			return IIO_VAL_FRACTIONAL;
		default:
			return -EINVAL;
		}
	}

	return -EINVAL;
}

static int ltc2983_reg_access(struct iio_dev *indio_dev,
			      unsigned int reg,
			      unsigned int writeval,
			      unsigned int *readval)
{
	struct ltc2983_data *st = iio_priv(indio_dev);

	if (readval)
		return regmap_read(st->regmap, reg, readval);
	else
		return regmap_write(st->regmap, reg, writeval);
}

static irqreturn_t ltc2983_irq_handler(int irq, void *data)
{
	struct ltc2983_data *st = data;

	complete(&st->completion);
	return IRQ_HANDLED;
}

#define LTC2983_CHAN(__type, index, __address) ({ \
	struct iio_chan_spec __chan = { \
		.type = __type, \
		.indexed = 1, \
		.channel = index, \
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
		.address = __address, \
	}; \
	__chan; \
})

static int ltc2983_parse_dt(struct ltc2983_data *st)
{
	struct device_node *child;
	struct device *dev = &st->spi->dev;
	int ret = 0, chan = 0, channel_avail_mask = 0;

	of_property_read_u32(dev->of_node, "adi,mux-delay-config-us",
			     &st->mux_delay_config);

	of_property_read_u32(dev->of_node, "adi,filter-notch-freq",
			     &st->filter_notch_freq);

	st->num_channels = of_get_available_child_count(dev->of_node);
	st->sensors = devm_kcalloc(dev, st->num_channels, sizeof(*st->sensors),
				   GFP_KERNEL);
	if (!st->sensors)
		return -ENOMEM;

	st->iio_channels = st->num_channels;
	for_each_available_child_of_node(dev->of_node, child) {
		struct ltc2983_sensor sensor;

		ret = of_property_read_u32(child, "reg", &sensor.chan);
		if (ret) {
			dev_err(dev, "reg property must given for child nodes\n");
			return ret;
		}

		/* check if we have a valid channel */
		if (sensor.chan < LTC2983_MIN_CHANNELS_NR ||
		    sensor.chan > LTC2983_MAX_CHANNELS_NR) {
			dev_err(dev,
				"chan:%d must be from 1 to 20\n", sensor.chan);
			return -EINVAL;
		} else if (channel_avail_mask & BIT(sensor.chan)) {
			dev_err(dev, "chan:%d already in use\n", sensor.chan);
			return -EINVAL;
		}

		ret = of_property_read_u32(child, "adi,sensor-type",
					       &sensor.type);
		if (ret) {
			dev_err(dev,
				"adi,sensor-type property must given for child nodes\n");
			return ret;
		}

		dev_dbg(dev, "Create new sensor, type %u, chann %u",
								sensor.type,
								sensor.chan);

		if (sensor.type >= LTC2983_SENSOR_THERMOCOUPLE &&
		    sensor.type <= LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
			st->sensors[chan] = ltc2983_thermocouple_new(child, st,
								     &sensor);
		} else if (sensor.type >= LTC2983_SENSOR_RTD &&
			   sensor.type <= LTC2983_SENSOR_RTD_CUSTOM) {
			st->sensors[chan] = ltc2983_rtd_new(child, st, &sensor);
		} else if (sensor.type >= LTC2983_SENSOR_THERMISTOR &&
			   sensor.type <= LTC2983_SENSOR_THERMISTOR_CUSTOM) {
			st->sensors[chan] = ltc2983_thermistor_new(child, st,
								   &sensor);
		} else if (sensor.type == LTC2983_SENSOR_DIODE) {
			st->sensors[chan] = ltc2983_diode_new(child, st,
							      &sensor);
		} else if (sensor.type == LTC2983_SENSOR_SENSE_RESISTOR) {
			st->sensors[chan] = ltc2983_r_sense_new(child, st,
								&sensor);
			/* don't add rsense to iio */
			st->iio_channels--;
		} else if (sensor.type == LTC2983_SENSOR_DIRECT_ADC) {
			st->sensors[chan] = ltc2983_adc_new(child, st, &sensor);
		} else {
			dev_err(dev, "Unknown sensor type %d\n", sensor.type);
			return -EINVAL;
		}

		if (IS_ERR(st->sensors[chan])) {
			dev_err(dev, "Failed to create sensor %ld",
				PTR_ERR(st->sensors[chan]));
			return PTR_ERR(st->sensors[chan]);
		}
		/* set generic sensor parameters */
		st->sensors[chan]->chan = sensor.chan;
		st->sensors[chan]->type = sensor.type;

		channel_avail_mask |= BIT(sensor.chan);
		chan++;
	}

	return 0;
}

static int ltc2983_setup(struct ltc2983_data *st, bool assign_iio)
{
	u32 iio_chan_t = 0, iio_chan_v = 0, chan, iio_idx = 0;
	int ret;
	unsigned long time;

	/* make sure the device is up */
	time = wait_for_completion_timeout(&st->completion,
					    msecs_to_jiffies(250));

	if (!time) {
		dev_err(&st->spi->dev, "Device startup timed out\n");
		return -ETIMEDOUT;
	}

	st->iio_chan = devm_kzalloc(&st->spi->dev,
				    st->iio_channels * sizeof(*st->iio_chan),
				    GFP_KERNEL);

	if (!st->iio_chan)
		return -ENOMEM;

	ret = regmap_update_bits(st->regmap, LTC2983_GLOBAL_CONFIG_REG,
				 LTC2983_NOTCH_FREQ_MASK,
				 LTC2983_NOTCH_FREQ(st->filter_notch_freq));
	if (ret)
		return ret;

	ret = regmap_write(st->regmap, LTC2983_MUX_CONFIG_REG,
			   st->mux_delay_config);
	if (ret)
		return ret;

	for (chan = 0; chan < st->num_channels; chan++) {
		u32 chan_type = 0, *iio_chan;

		ret = st->sensors[chan]->assign_chan(st, st->sensors[chan]);
		if (ret)
			return ret;
		/*
		 * The assign_iio flag is necessary for when the device is
		 * coming out of sleep. In that case, we just need to
		 * re-configure the device channels.
		 * We also don't assign iio channels for rsense.
		 */
		if (st->sensors[chan]->type == LTC2983_SENSOR_SENSE_RESISTOR ||
		    !assign_iio)
			continue;

		/* assign iio channel */
		if (st->sensors[chan]->type != LTC2983_SENSOR_DIRECT_ADC) {
			chan_type = IIO_TEMP;
			iio_chan = &iio_chan_t;
		} else {
			chan_type = IIO_VOLTAGE;
			iio_chan = &iio_chan_v;
		}

		/*
		 * add chan as the iio .address so that, we can directly
		 * reference the sensor given the iio_chan_spec
		 */
		st->iio_chan[iio_idx++] = LTC2983_CHAN(chan_type, (*iio_chan)++,
						       chan);
	}

	return 0;
}

static const struct regmap_range ltc2983_reg_ranges[] = {
	regmap_reg_range(LTC2983_STATUS_REG, LTC2983_STATUS_REG),
	regmap_reg_range(LTC2983_TEMP_RES_START_REG, LTC2983_TEMP_RES_END_REG),
	regmap_reg_range(LTC2983_GLOBAL_CONFIG_REG, LTC2983_GLOBAL_CONFIG_REG),
	regmap_reg_range(LTC2983_MULT_CHANNEL_START_REG,
			 LTC2983_MULT_CHANNEL_END_REG),
	regmap_reg_range(LTC2983_MUX_CONFIG_REG, LTC2983_MUX_CONFIG_REG),
	regmap_reg_range(LTC2983_CHAN_ASSIGN_START_REG,
			 LTC2983_CHAN_ASSIGN_END_REG),
	regmap_reg_range(LTC2983_CUST_SENS_TBL_START_REG,
			 LTC2983_CUST_SENS_TBL_END_REG),
};

static const struct regmap_access_table ltc2983_reg_table = {
	.yes_ranges = ltc2983_reg_ranges,
	.n_yes_ranges = ARRAY_SIZE(ltc2983_reg_ranges),
};

/*
 *  The reg_bits are actually 12 but the device needs the first *complete*
 *  byte for the command (R/W).
 */
static const struct regmap_config ltc2983_regmap_config = {
	.reg_bits = 24,
	.val_bits = 8,
	.wr_table = &ltc2983_reg_table,
	.rd_table = &ltc2983_reg_table,
	.read_flag_mask = GENMASK(1, 0),
	.write_flag_mask = BIT(1),
};

static const struct  iio_info ltc2983_iio_info = {
	.read_raw = ltc2983_read_raw,
	.debugfs_reg_access = ltc2983_reg_access,
};

static int ltc2983_probe(struct spi_device *spi)
{
	struct ltc2983_data *st;
	struct iio_dev *indio_dev;
	const char *name = spi_get_device_id(spi)->name;
	int ret;

	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
	if (!indio_dev)
		return -ENOMEM;

	st = iio_priv(indio_dev);

	st->regmap = devm_regmap_init_spi(spi, &ltc2983_regmap_config);
	if (IS_ERR(st->regmap)) {
		dev_err(&spi->dev, "Failed to initialize regmap\n");
		return PTR_ERR(st->regmap);
	}

	mutex_init(&st->lock);
	init_completion(&st->completion);
	st->spi = spi;
	spi_set_drvdata(spi, st);

	ret = ltc2983_parse_dt(st);
	if (ret)
		return ret;
	/*
	 * let's request the irq now so it is used to sync the device
	 * startup in ltc2983_setup()
	 */
	ret = devm_request_irq(&spi->dev, spi->irq, ltc2983_irq_handler,
			       IRQF_TRIGGER_RISING, name, st);
	if (ret) {
		dev_err(&spi->dev, "failed to request an irq, %d", ret);
		return ret;
	}

	ret = ltc2983_setup(st, true);
	if (ret)
		return ret;

	indio_dev->name = name;
	indio_dev->num_channels = st->iio_channels;
	indio_dev->channels = st->iio_chan;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->info = &ltc2983_iio_info;

	return devm_iio_device_register(&spi->dev, indio_dev);
}

static int __maybe_unused ltc2983_resume(struct device *dev)
{
	struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));
	int dummy;

	/* dummy read to bring the device out of sleep */
	regmap_read(st->regmap, LTC2983_STATUS_REG, &dummy);
	/* we need to re-assign the channels */
	return ltc2983_setup(st, false);
}

static int __maybe_unused ltc2983_suspend(struct device *dev)
{
	struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));

	return regmap_write(st->regmap, LTC2983_STATUS_REG, LTC2983_SLEEP);
}

static SIMPLE_DEV_PM_OPS(ltc2983_pm_ops, ltc2983_suspend, ltc2983_resume);

static const struct spi_device_id ltc2983_id_table[] = {
	{ "ltc2983" },
	{},
};
MODULE_DEVICE_TABLE(spi, ltc2983_id_table);

static const struct of_device_id ltc2983_of_match[] = {
	{ .compatible = "adi,ltc2983" },
	{},
};
MODULE_DEVICE_TABLE(of, ltc2983_of_match);

static struct spi_driver ltc2983_driver = {
	.driver = {
		.name = "ltc2983",
		.of_match_table = ltc2983_of_match,
		.pm = &ltc2983_pm_ops,
	},
	.probe = ltc2983_probe,
	.id_table = ltc2983_id_table,
};

module_spi_driver(ltc2983_driver);

MODULE_AUTHOR("Nuno Sa <nuno.sa@analog.com>");
MODULE_DESCRIPTION("Analog Devices LTC2983 SPI Temperature sensors");
MODULE_LICENSE("GPL");