summaryrefslogtreecommitdiffstats
path: root/drivers/iio/accel/sca3000.c
blob: f33dadf7b2621b51aefd2b026815f6c959905137 (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
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
/*
 * sca3000_core.c -- support VTI sca3000 series accelerometers via SPI
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * Copyright (c) 2009 Jonathan Cameron <jic23@kernel.org>
 *
 * See industrialio/accels/sca3000.h for comments.
 */

#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/spi/spi.h>
#include <linux/sysfs.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/events.h>
#include <linux/iio/buffer.h>
#include <linux/iio/kfifo_buf.h>

#define SCA3000_WRITE_REG(a) (((a) << 2) | 0x02)
#define SCA3000_READ_REG(a) ((a) << 2)

#define SCA3000_REG_REVID_ADDR				0x00
#define   SCA3000_REG_REVID_MAJOR_MASK			GENMASK(8, 4)
#define   SCA3000_REG_REVID_MINOR_MASK			GENMASK(3, 0)

#define SCA3000_REG_STATUS_ADDR				0x02
#define   SCA3000_LOCKED				BIT(5)
#define   SCA3000_EEPROM_CS_ERROR			BIT(1)
#define   SCA3000_SPI_FRAME_ERROR			BIT(0)

/* All reads done using register decrement so no need to directly access LSBs */
#define SCA3000_REG_X_MSB_ADDR				0x05
#define SCA3000_REG_Y_MSB_ADDR				0x07
#define SCA3000_REG_Z_MSB_ADDR				0x09

#define SCA3000_REG_RING_OUT_ADDR			0x0f

/* Temp read untested - the e05 doesn't have the sensor */
#define SCA3000_REG_TEMP_MSB_ADDR			0x13

#define SCA3000_REG_MODE_ADDR				0x14
#define SCA3000_MODE_PROT_MASK				0x28
#define   SCA3000_REG_MODE_RING_BUF_ENABLE		BIT(7)
#define   SCA3000_REG_MODE_RING_BUF_8BIT		BIT(6)

/*
 * Free fall detection triggers an interrupt if the acceleration
 * is below a threshold for equivalent of 25cm drop
 */
#define   SCA3000_REG_MODE_FREE_FALL_DETECT		BIT(4)
#define   SCA3000_REG_MODE_MEAS_MODE_NORMAL		0x00
#define   SCA3000_REG_MODE_MEAS_MODE_OP_1		0x01
#define   SCA3000_REG_MODE_MEAS_MODE_OP_2		0x02

/*
 * In motion detection mode the accelerations are band pass filtered
 * (approx 1 - 25Hz) and then a programmable threshold used to trigger
 * and interrupt.
 */
#define   SCA3000_REG_MODE_MEAS_MODE_MOT_DET		0x03
#define   SCA3000_REG_MODE_MODE_MASK			0x03

#define SCA3000_REG_BUF_COUNT_ADDR			0x15

#define SCA3000_REG_INT_STATUS_ADDR			0x16
#define   SCA3000_REG_INT_STATUS_THREE_QUARTERS		BIT(7)
#define   SCA3000_REG_INT_STATUS_HALF			BIT(6)

#define SCA3000_INT_STATUS_FREE_FALL			BIT(3)
#define SCA3000_INT_STATUS_Y_TRIGGER			BIT(2)
#define SCA3000_INT_STATUS_X_TRIGGER			BIT(1)
#define SCA3000_INT_STATUS_Z_TRIGGER			BIT(0)

/* Used to allow access to multiplexed registers */
#define SCA3000_REG_CTRL_SEL_ADDR			0x18
/* Only available for SCA3000-D03 and SCA3000-D01 */
#define   SCA3000_REG_CTRL_SEL_I2C_DISABLE		0x01
#define   SCA3000_REG_CTRL_SEL_MD_CTRL			0x02
#define   SCA3000_REG_CTRL_SEL_MD_Y_TH			0x03
#define   SCA3000_REG_CTRL_SEL_MD_X_TH			0x04
#define   SCA3000_REG_CTRL_SEL_MD_Z_TH			0x05
/*
 * BE VERY CAREFUL WITH THIS, IF 3 BITS ARE NOT SET the device
 * will not function
 */
#define   SCA3000_REG_CTRL_SEL_OUT_CTRL			0x0B

#define     SCA3000_REG_OUT_CTRL_PROT_MASK		0xE0
#define     SCA3000_REG_OUT_CTRL_BUF_X_EN		0x10
#define     SCA3000_REG_OUT_CTRL_BUF_Y_EN		0x08
#define     SCA3000_REG_OUT_CTRL_BUF_Z_EN		0x04
#define     SCA3000_REG_OUT_CTRL_BUF_DIV_MASK		0x03
#define     SCA3000_REG_OUT_CTRL_BUF_DIV_4		0x02
#define     SCA3000_REG_OUT_CTRL_BUF_DIV_2		0x01


/*
 * Control which motion detector interrupts are on.
 * For now only OR combinations are supported.
 */
#define SCA3000_MD_CTRL_PROT_MASK			0xC0
#define SCA3000_MD_CTRL_OR_Y				BIT(0)
#define SCA3000_MD_CTRL_OR_X				BIT(1)
#define SCA3000_MD_CTRL_OR_Z				BIT(2)
/* Currently unsupported */
#define SCA3000_MD_CTRL_AND_Y				BIT(3)
#define SCA3000_MD_CTRL_AND_X				BIT(4)
#define SAC3000_MD_CTRL_AND_Z				BIT(5)

/*
 * Some control registers of complex access methods requiring this register to
 * be used to remove a lock.
 */
#define SCA3000_REG_UNLOCK_ADDR				0x1e

#define SCA3000_REG_INT_MASK_ADDR			0x21
#define   SCA3000_REG_INT_MASK_PROT_MASK		0x1C

#define   SCA3000_REG_INT_MASK_RING_THREE_QUARTER	BIT(7)
#define   SCA3000_REG_INT_MASK_RING_HALF		BIT(6)

#define SCA3000_REG_INT_MASK_ALL_INTS			0x02
#define SCA3000_REG_INT_MASK_ACTIVE_HIGH		0x01
#define SCA3000_REG_INT_MASK_ACTIVE_LOW			0x00
/* Values of multiplexed registers (write to ctrl_data after select) */
#define SCA3000_REG_CTRL_DATA_ADDR			0x22

/*
 * Measurement modes available on some sca3000 series chips. Code assumes others
 * may become available in the future.
 *
 * Bypass - Bypass the low-pass filter in the signal channel so as to increase
 *          signal bandwidth.
 *
 * Narrow - Narrow low-pass filtering of the signal channel and half output
 *          data rate by decimation.
 *
 * Wide - Widen low-pass filtering of signal channel to increase bandwidth
 */
#define SCA3000_OP_MODE_BYPASS				0x01
#define SCA3000_OP_MODE_NARROW				0x02
#define SCA3000_OP_MODE_WIDE				0x04
#define SCA3000_MAX_TX 6
#define SCA3000_MAX_RX 2

/**
 * struct sca3000_state - device instance state information
 * @us:			the associated spi device
 * @info:			chip variant information
 * @last_timestamp:		the timestamp of the last event
 * @mo_det_use_count:		reference counter for the motion detection unit
 * @lock:			lock used to protect elements of sca3000_state
 *				and the underlying device state.
 * @tx:			dma-able transmit buffer
 * @rx:			dma-able receive buffer
 **/
struct sca3000_state {
	struct spi_device		*us;
	const struct sca3000_chip_info	*info;
	s64				last_timestamp;
	int				mo_det_use_count;
	struct mutex			lock;
	/* Can these share a cacheline ? */
	u8				rx[384] ____cacheline_aligned;
	u8				tx[6] ____cacheline_aligned;
};

/**
 * struct sca3000_chip_info - model dependent parameters
 * @scale:			scale * 10^-6
 * @temp_output:		some devices have temperature sensors.
 * @measurement_mode_freq:	normal mode sampling frequency
 * @measurement_mode_3db_freq:	3db cutoff frequency of the low pass filter for
 * the normal measurement mode.
 * @option_mode_1:		first optional mode. Not all models have one
 * @option_mode_1_freq:		option mode 1 sampling frequency
 * @option_mode_1_3db_freq:	3db cutoff frequency of the low pass filter for
 * the first option mode.
 * @option_mode_2:		second optional mode. Not all chips have one
 * @option_mode_2_freq:		option mode 2 sampling frequency
 * @option_mode_2_3db_freq:	3db cutoff frequency of the low pass filter for
 * the second option mode.
 * @mod_det_mult_xz:		Bit wise multipliers to calculate the threshold
 * for motion detection in the x and z axis.
 * @mod_det_mult_y:		Bit wise multipliers to calculate the threshold
 * for motion detection in the y axis.
 *
 * This structure is used to hold information about the functionality of a given
 * sca3000 variant.
 **/
struct sca3000_chip_info {
	unsigned int		scale;
	bool			temp_output;
	int			measurement_mode_freq;
	int			measurement_mode_3db_freq;
	int			option_mode_1;
	int			option_mode_1_freq;
	int			option_mode_1_3db_freq;
	int			option_mode_2;
	int			option_mode_2_freq;
	int			option_mode_2_3db_freq;
	int			mot_det_mult_xz[6];
	int			mot_det_mult_y[7];
};

enum sca3000_variant {
	d01,
	e02,
	e04,
	e05,
};

/*
 * Note where option modes are not defined, the chip simply does not
 * support any.
 * Other chips in the sca3000 series use i2c and are not included here.
 *
 * Some of these devices are only listed in the family data sheet and
 * do not actually appear to be available.
 */
static const struct sca3000_chip_info sca3000_spi_chip_info_tbl[] = {
	[d01] = {
		.scale = 7357,
		.temp_output = true,
		.measurement_mode_freq = 250,
		.measurement_mode_3db_freq = 45,
		.option_mode_1 = SCA3000_OP_MODE_BYPASS,
		.option_mode_1_freq = 250,
		.option_mode_1_3db_freq = 70,
		.mot_det_mult_xz = {50, 100, 200, 350, 650, 1300},
		.mot_det_mult_y = {50, 100, 150, 250, 450, 850, 1750},
	},
	[e02] = {
		.scale = 9810,
		.measurement_mode_freq = 125,
		.measurement_mode_3db_freq = 40,
		.option_mode_1 = SCA3000_OP_MODE_NARROW,
		.option_mode_1_freq = 63,
		.option_mode_1_3db_freq = 11,
		.mot_det_mult_xz = {100, 150, 300, 550, 1050, 2050},
		.mot_det_mult_y = {50, 100, 200, 350, 700, 1350, 2700},
	},
	[e04] = {
		.scale = 19620,
		.measurement_mode_freq = 100,
		.measurement_mode_3db_freq = 38,
		.option_mode_1 = SCA3000_OP_MODE_NARROW,
		.option_mode_1_freq = 50,
		.option_mode_1_3db_freq = 9,
		.option_mode_2 = SCA3000_OP_MODE_WIDE,
		.option_mode_2_freq = 400,
		.option_mode_2_3db_freq = 70,
		.mot_det_mult_xz = {200, 300, 600, 1100, 2100, 4100},
		.mot_det_mult_y = {100, 200, 400, 7000, 1400, 2700, 54000},
	},
	[e05] = {
		.scale = 61313,
		.measurement_mode_freq = 200,
		.measurement_mode_3db_freq = 60,
		.option_mode_1 = SCA3000_OP_MODE_NARROW,
		.option_mode_1_freq = 50,
		.option_mode_1_3db_freq = 9,
		.option_mode_2 = SCA3000_OP_MODE_WIDE,
		.option_mode_2_freq = 400,
		.option_mode_2_3db_freq = 75,
		.mot_det_mult_xz = {600, 900, 1700, 3200, 6100, 11900},
		.mot_det_mult_y = {300, 600, 1200, 2000, 4100, 7800, 15600},
	},
};

static int sca3000_write_reg(struct sca3000_state *st, u8 address, u8 val)
{
	st->tx[0] = SCA3000_WRITE_REG(address);
	st->tx[1] = val;
	return spi_write(st->us, st->tx, 2);
}

static int sca3000_read_data_short(struct sca3000_state *st,
				   u8 reg_address_high,
				   int len)
{
	struct spi_transfer xfer[2] = {
		{
			.len = 1,
			.tx_buf = st->tx,
		}, {
			.len = len,
			.rx_buf = st->rx,
		}
	};
	st->tx[0] = SCA3000_READ_REG(reg_address_high);

	return spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
}

/**
 * sca3000_reg_lock_on() - test if the ctrl register lock is on
 * @st: Driver specific device instance data.
 *
 * Lock must be held.
 **/
static int sca3000_reg_lock_on(struct sca3000_state *st)
{
	int ret;

	ret = sca3000_read_data_short(st, SCA3000_REG_STATUS_ADDR, 1);
	if (ret < 0)
		return ret;

	return !(st->rx[0] & SCA3000_LOCKED);
}

/**
 * __sca3000_unlock_reg_lock() - unlock the control registers
 * @st: Driver specific device instance data.
 *
 * Note the device does not appear to support doing this in a single transfer.
 * This should only ever be used as part of ctrl reg read.
 * Lock must be held before calling this
 */
static int __sca3000_unlock_reg_lock(struct sca3000_state *st)
{
	struct spi_transfer xfer[3] = {
		{
			.len = 2,
			.cs_change = 1,
			.tx_buf = st->tx,
		}, {
			.len = 2,
			.cs_change = 1,
			.tx_buf = st->tx + 2,
		}, {
			.len = 2,
			.tx_buf = st->tx + 4,
		},
	};
	st->tx[0] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
	st->tx[1] = 0x00;
	st->tx[2] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
	st->tx[3] = 0x50;
	st->tx[4] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
	st->tx[5] = 0xA0;

	return spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
}

/**
 * sca3000_write_ctrl_reg() write to a lock protect ctrl register
 * @st: Driver specific device instance data.
 * @sel: selects which registers we wish to write to
 * @val: the value to be written
 *
 * Certain control registers are protected against overwriting by the lock
 * register and use a shared write address. This function allows writing of
 * these registers.
 * Lock must be held.
 */
static int sca3000_write_ctrl_reg(struct sca3000_state *st,
				  u8 sel,
				  uint8_t val)
{
	int ret;

	ret = sca3000_reg_lock_on(st);
	if (ret < 0)
		goto error_ret;
	if (ret) {
		ret = __sca3000_unlock_reg_lock(st);
		if (ret)
			goto error_ret;
	}

	/* Set the control select register */
	ret = sca3000_write_reg(st, SCA3000_REG_CTRL_SEL_ADDR, sel);
	if (ret)
		goto error_ret;

	/* Write the actual value into the register */
	ret = sca3000_write_reg(st, SCA3000_REG_CTRL_DATA_ADDR, val);

error_ret:
	return ret;
}

/**
 * sca3000_read_ctrl_reg() read from lock protected control register.
 * @st: Driver specific device instance data.
 * @ctrl_reg: Which ctrl register do we want to read.
 *
 * Lock must be held.
 */
static int sca3000_read_ctrl_reg(struct sca3000_state *st,
				 u8 ctrl_reg)
{
	int ret;

	ret = sca3000_reg_lock_on(st);
	if (ret < 0)
		goto error_ret;
	if (ret) {
		ret = __sca3000_unlock_reg_lock(st);
		if (ret)
			goto error_ret;
	}
	/* Set the control select register */
	ret = sca3000_write_reg(st, SCA3000_REG_CTRL_SEL_ADDR, ctrl_reg);
	if (ret)
		goto error_ret;
	ret = sca3000_read_data_short(st, SCA3000_REG_CTRL_DATA_ADDR, 1);
	if (ret)
		goto error_ret;
	return st->rx[0];
error_ret:
	return ret;
}

/**
 * sca3000_show_rev() - sysfs interface to read the chip revision number
 * @indio_dev: Device instance specific generic IIO data.
 * Driver specific device instance data can be obtained via
 * via iio_priv(indio_dev)
 */
static int sca3000_print_rev(struct iio_dev *indio_dev)
{
	int ret;
	struct sca3000_state *st = iio_priv(indio_dev);

	mutex_lock(&st->lock);
	ret = sca3000_read_data_short(st, SCA3000_REG_REVID_ADDR, 1);
	if (ret < 0)
		goto error_ret;
	dev_info(&indio_dev->dev,
		 "sca3000 revision major=%lu, minor=%lu\n",
		 st->rx[0] & SCA3000_REG_REVID_MAJOR_MASK,
		 st->rx[0] & SCA3000_REG_REVID_MINOR_MASK);
error_ret:
	mutex_unlock(&st->lock);

	return ret;
}

static ssize_t
sca3000_show_available_3db_freqs(struct device *dev,
				 struct device_attribute *attr,
				 char *buf)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct sca3000_state *st = iio_priv(indio_dev);
	int len;

	len = sprintf(buf, "%d", st->info->measurement_mode_3db_freq);
	if (st->info->option_mode_1)
		len += sprintf(buf + len, " %d",
			       st->info->option_mode_1_3db_freq);
	if (st->info->option_mode_2)
		len += sprintf(buf + len, " %d",
			       st->info->option_mode_2_3db_freq);
	len += sprintf(buf + len, "\n");

	return len;
}

static IIO_DEVICE_ATTR(in_accel_filter_low_pass_3db_frequency_available,
		       S_IRUGO, sca3000_show_available_3db_freqs,
		       NULL, 0);

static const struct iio_event_spec sca3000_event = {
	.type = IIO_EV_TYPE_MAG,
	.dir = IIO_EV_DIR_RISING,
	.mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
};

/*
 * Note the hack in the number of bits to pretend we have 2 more than
 * we do in the fifo.
 */
#define SCA3000_CHAN(index, mod)				\
	{							\
		.type = IIO_ACCEL,				\
		.modified = 1,					\
		.channel2 = mod,				\
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |\
			BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY),\
		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
		.address = index,				\
		.scan_index = index,				\
		.scan_type = {					\
			.sign = 's',				\
			.realbits = 13,				\
			.storagebits = 16,			\
			.shift = 3,				\
			.endianness = IIO_BE,			\
		},						\
		.event_spec = &sca3000_event,			\
		.num_event_specs = 1,				\
	}

static const struct iio_event_spec sca3000_freefall_event_spec = {
	.type = IIO_EV_TYPE_MAG,
	.dir = IIO_EV_DIR_FALLING,
	.mask_separate = BIT(IIO_EV_INFO_ENABLE) |
		BIT(IIO_EV_INFO_PERIOD),
};

static const struct iio_chan_spec sca3000_channels[] = {
	SCA3000_CHAN(0, IIO_MOD_X),
	SCA3000_CHAN(1, IIO_MOD_Y),
	SCA3000_CHAN(2, IIO_MOD_Z),
	{
		.type = IIO_ACCEL,
		.modified = 1,
		.channel2 = IIO_MOD_X_AND_Y_AND_Z,
		.scan_index = -1, /* Fake channel */
		.event_spec = &sca3000_freefall_event_spec,
		.num_event_specs = 1,
	},
};

static const struct iio_chan_spec sca3000_channels_with_temp[] = {
	SCA3000_CHAN(0, IIO_MOD_X),
	SCA3000_CHAN(1, IIO_MOD_Y),
	SCA3000_CHAN(2, IIO_MOD_Z),
	{
		.type = IIO_TEMP,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
			BIT(IIO_CHAN_INFO_OFFSET),
		/* No buffer support */
		.scan_index = -1,
	},
	{
		.type = IIO_ACCEL,
		.modified = 1,
		.channel2 = IIO_MOD_X_AND_Y_AND_Z,
		.scan_index = -1, /* Fake channel */
		.event_spec = &sca3000_freefall_event_spec,
		.num_event_specs = 1,
	},
};

static u8 sca3000_addresses[3][3] = {
	[0] = {SCA3000_REG_X_MSB_ADDR, SCA3000_REG_CTRL_SEL_MD_X_TH,
	       SCA3000_MD_CTRL_OR_X},
	[1] = {SCA3000_REG_Y_MSB_ADDR, SCA3000_REG_CTRL_SEL_MD_Y_TH,
	       SCA3000_MD_CTRL_OR_Y},
	[2] = {SCA3000_REG_Z_MSB_ADDR, SCA3000_REG_CTRL_SEL_MD_Z_TH,
	       SCA3000_MD_CTRL_OR_Z},
};

/**
 * __sca3000_get_base_freq() - obtain mode specific base frequency
 * @st: Private driver specific device instance specific state.
 * @info: chip type specific information.
 * @base_freq: Base frequency for the current measurement mode.
 *
 * lock must be held
 */
static inline int __sca3000_get_base_freq(struct sca3000_state *st,
					  const struct sca3000_chip_info *info,
					  int *base_freq)
{
	int ret;

	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
	if (ret)
		goto error_ret;
	switch (SCA3000_REG_MODE_MODE_MASK & st->rx[0]) {
	case SCA3000_REG_MODE_MEAS_MODE_NORMAL:
		*base_freq = info->measurement_mode_freq;
		break;
	case SCA3000_REG_MODE_MEAS_MODE_OP_1:
		*base_freq = info->option_mode_1_freq;
		break;
	case SCA3000_REG_MODE_MEAS_MODE_OP_2:
		*base_freq = info->option_mode_2_freq;
		break;
	default:
		ret = -EINVAL;
	}
error_ret:
	return ret;
}

/**
 * sca3000_read_raw_samp_freq() - read_raw handler for IIO_CHAN_INFO_SAMP_FREQ
 * @st: Private driver specific device instance specific state.
 * @val: The frequency read back.
 *
 * lock must be held
 **/
static int sca3000_read_raw_samp_freq(struct sca3000_state *st, int *val)
{
	int ret;

	ret = __sca3000_get_base_freq(st, st->info, val);
	if (ret)
		return ret;

	ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL);
	if (ret < 0)
		return ret;

	if (*val > 0) {
		ret &= SCA3000_REG_OUT_CTRL_BUF_DIV_MASK;
		switch (ret) {
		case SCA3000_REG_OUT_CTRL_BUF_DIV_2:
			*val /= 2;
			break;
		case SCA3000_REG_OUT_CTRL_BUF_DIV_4:
			*val /= 4;
			break;
		}
	}

	return 0;
}

/**
 * sca3000_write_raw_samp_freq() - write_raw handler for IIO_CHAN_INFO_SAMP_FREQ
 * @st: Private driver specific device instance specific state.
 * @val: The frequency desired.
 *
 * lock must be held
 */
static int sca3000_write_raw_samp_freq(struct sca3000_state *st, int val)
{
	int ret, base_freq, ctrlval;

	ret = __sca3000_get_base_freq(st, st->info, &base_freq);
	if (ret)
		return ret;

	ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL);
	if (ret < 0)
		return ret;

	ctrlval = ret & ~SCA3000_REG_OUT_CTRL_BUF_DIV_MASK;

	if (val == base_freq / 2)
		ctrlval |= SCA3000_REG_OUT_CTRL_BUF_DIV_2;
	if (val == base_freq / 4)
		ctrlval |= SCA3000_REG_OUT_CTRL_BUF_DIV_4;
	else if (val != base_freq)
		return -EINVAL;

	return sca3000_write_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL,
				     ctrlval);
}

static int sca3000_read_3db_freq(struct sca3000_state *st, int *val)
{
	int ret;

	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
	if (ret)
		return ret;

	/* mask bottom 2 bits - only ones that are relevant */
	st->rx[0] &= SCA3000_REG_MODE_MODE_MASK;
	switch (st->rx[0]) {
	case SCA3000_REG_MODE_MEAS_MODE_NORMAL:
		*val = st->info->measurement_mode_3db_freq;
		return IIO_VAL_INT;
	case SCA3000_REG_MODE_MEAS_MODE_MOT_DET:
		return -EBUSY;
	case SCA3000_REG_MODE_MEAS_MODE_OP_1:
		*val = st->info->option_mode_1_3db_freq;
		return IIO_VAL_INT;
	case SCA3000_REG_MODE_MEAS_MODE_OP_2:
		*val = st->info->option_mode_2_3db_freq;
		return IIO_VAL_INT;
	default:
		return -EINVAL;
	}
}

static int sca3000_write_3db_freq(struct sca3000_state *st, int val)
{
	int ret;
	int mode;

	if (val == st->info->measurement_mode_3db_freq)
		mode = SCA3000_REG_MODE_MEAS_MODE_NORMAL;
	else if (st->info->option_mode_1 &&
		 (val == st->info->option_mode_1_3db_freq))
		mode = SCA3000_REG_MODE_MEAS_MODE_OP_1;
	else if (st->info->option_mode_2 &&
		 (val == st->info->option_mode_2_3db_freq))
		mode = SCA3000_REG_MODE_MEAS_MODE_OP_2;
	else
		return -EINVAL;
	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
	if (ret)
		return ret;

	st->rx[0] &= ~SCA3000_REG_MODE_MODE_MASK;
	st->rx[0] |= (mode & SCA3000_REG_MODE_MODE_MASK);

	return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR, st->rx[0]);
}

static int sca3000_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val,
			    int *val2,
			    long mask)
{
	struct sca3000_state *st = iio_priv(indio_dev);
	int ret;
	u8 address;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		mutex_lock(&st->lock);
		if (chan->type == IIO_ACCEL) {
			if (st->mo_det_use_count) {
				mutex_unlock(&st->lock);
				return -EBUSY;
			}
			address = sca3000_addresses[chan->address][0];
			ret = sca3000_read_data_short(st, address, 2);
			if (ret < 0) {
				mutex_unlock(&st->lock);
				return ret;
			}
			*val = (be16_to_cpup((__be16 *)st->rx) >> 3) & 0x1FFF;
			*val = ((*val) << (sizeof(*val) * 8 - 13)) >>
				(sizeof(*val) * 8 - 13);
		} else {
			/* get the temperature when available */
			ret = sca3000_read_data_short(st,
						      SCA3000_REG_TEMP_MSB_ADDR,
						      2);
			if (ret < 0) {
				mutex_unlock(&st->lock);
				return ret;
			}
			*val = ((st->rx[0] & 0x3F) << 3) |
			       ((st->rx[1] & 0xE0) >> 5);
		}
		mutex_unlock(&st->lock);
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		*val = 0;
		if (chan->type == IIO_ACCEL)
			*val2 = st->info->scale;
		else /* temperature */
			*val2 = 555556;
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_OFFSET:
		*val = -214;
		*val2 = 600000;
		return IIO_VAL_INT_PLUS_MICRO;
	case IIO_CHAN_INFO_SAMP_FREQ:
		mutex_lock(&st->lock);
		ret = sca3000_read_raw_samp_freq(st, val);
		mutex_unlock(&st->lock);
		return ret ? ret : IIO_VAL_INT;
	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
		mutex_lock(&st->lock);
		ret = sca3000_read_3db_freq(st, val);
		mutex_unlock(&st->lock);
		return ret;
	default:
		return -EINVAL;
	}
}

static int sca3000_write_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     int val, int val2, long mask)
{
	struct sca3000_state *st = iio_priv(indio_dev);
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_SAMP_FREQ:
		if (val2)
			return -EINVAL;
		mutex_lock(&st->lock);
		ret = sca3000_write_raw_samp_freq(st, val);
		mutex_unlock(&st->lock);
		return ret;
	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
		if (val2)
			return -EINVAL;
		mutex_lock(&st->lock);
		ret = sca3000_write_3db_freq(st, val);
		mutex_unlock(&st->lock);
	default:
		return -EINVAL;
	}

	return ret;
}

/**
 * sca3000_read_av_freq() - sysfs function to get available frequencies
 * @dev: Device structure for this device.
 * @attr: Description of the attribute.
 * @buf: Incoming string
 *
 * The later modes are only relevant to the ring buffer - and depend on current
 * mode. Note that data sheet gives rather wide tolerances for these so integer
 * division will give good enough answer and not all chips have them specified
 * at all.
 **/
static ssize_t sca3000_read_av_freq(struct device *dev,
				    struct device_attribute *attr,
				    char *buf)
{
	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
	struct sca3000_state *st = iio_priv(indio_dev);
	int len = 0, ret, val;

	mutex_lock(&st->lock);
	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
	val = st->rx[0];
	mutex_unlock(&st->lock);
	if (ret)
		goto error_ret;

	switch (val & SCA3000_REG_MODE_MODE_MASK) {
	case SCA3000_REG_MODE_MEAS_MODE_NORMAL:
		len += sprintf(buf + len, "%d %d %d\n",
			       st->info->measurement_mode_freq,
			       st->info->measurement_mode_freq / 2,
			       st->info->measurement_mode_freq / 4);
		break;
	case SCA3000_REG_MODE_MEAS_MODE_OP_1:
		len += sprintf(buf + len, "%d %d %d\n",
			       st->info->option_mode_1_freq,
			       st->info->option_mode_1_freq / 2,
			       st->info->option_mode_1_freq / 4);
		break;
	case SCA3000_REG_MODE_MEAS_MODE_OP_2:
		len += sprintf(buf + len, "%d %d %d\n",
			       st->info->option_mode_2_freq,
			       st->info->option_mode_2_freq / 2,
			       st->info->option_mode_2_freq / 4);
		break;
	}
	return len;
error_ret:
	return ret;
}

/*
 * Should only really be registered if ring buffer support is compiled in.
 * Does no harm however and doing it right would add a fair bit of complexity
 */
static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(sca3000_read_av_freq);

/**
 * sca3000_read_event_value() - query of a threshold or period
 **/
static int sca3000_read_event_value(struct iio_dev *indio_dev,
				    const struct iio_chan_spec *chan,
				    enum iio_event_type type,
				    enum iio_event_direction dir,
				    enum iio_event_info info,
				    int *val, int *val2)
{
	int ret, i;
	struct sca3000_state *st = iio_priv(indio_dev);

	switch (info) {
	case IIO_EV_INFO_VALUE:
		mutex_lock(&st->lock);
		ret = sca3000_read_ctrl_reg(st,
					    sca3000_addresses[chan->address][1]);
		mutex_unlock(&st->lock);
		if (ret < 0)
			return ret;
		*val = 0;
		if (chan->channel2 == IIO_MOD_Y)
			for_each_set_bit(i, (unsigned long *)&ret,
					 ARRAY_SIZE(st->info->mot_det_mult_y))
				*val += st->info->mot_det_mult_y[i];
		else
			for_each_set_bit(i, (unsigned long *)&ret,
					 ARRAY_SIZE(st->info->mot_det_mult_xz))
				*val += st->info->mot_det_mult_xz[i];

		return IIO_VAL_INT;
	case IIO_EV_INFO_PERIOD:
		*val = 0;
		*val2 = 226000;
		return IIO_VAL_INT_PLUS_MICRO;
	default:
		return -EINVAL;
	}
}

/**
 * sca3000_write_value() - control of threshold and period
 * @indio_dev: Device instance specific IIO information.
 * @chan: Description of the channel for which the event is being
 * configured.
 * @type: The type of event being configured, here magnitude rising
 * as everything else is read only.
 * @dir: Direction of the event (here rising)
 * @info: What information about the event are we configuring.
 * Here the threshold only.
 * @val: Integer part of the value being written..
 * @val2: Non integer part of the value being written. Here always 0.
 */
static int sca3000_write_event_value(struct iio_dev *indio_dev,
				     const struct iio_chan_spec *chan,
				     enum iio_event_type type,
				     enum iio_event_direction dir,
				     enum iio_event_info info,
				     int val, int val2)
{
	struct sca3000_state *st = iio_priv(indio_dev);
	int ret;
	int i;
	u8 nonlinear = 0;

	if (chan->channel2 == IIO_MOD_Y) {
		i = ARRAY_SIZE(st->info->mot_det_mult_y);
		while (i > 0)
			if (val >= st->info->mot_det_mult_y[--i]) {
				nonlinear |= (1 << i);
				val -= st->info->mot_det_mult_y[i];
			}
	} else {
		i = ARRAY_SIZE(st->info->mot_det_mult_xz);
		while (i > 0)
			if (val >= st->info->mot_det_mult_xz[--i]) {
				nonlinear |= (1 << i);
				val -= st->info->mot_det_mult_xz[i];
			}
	}

	mutex_lock(&st->lock);
	ret = sca3000_write_ctrl_reg(st,
				     sca3000_addresses[chan->address][1],
				     nonlinear);
	mutex_unlock(&st->lock);

	return ret;
}

static struct attribute *sca3000_attributes[] = {
	&iio_dev_attr_in_accel_filter_low_pass_3db_frequency_available.dev_attr.attr,
	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
	NULL,
};

static const struct attribute_group sca3000_attribute_group = {
	.attrs = sca3000_attributes,
};

static int sca3000_read_data(struct sca3000_state *st,
			     u8 reg_address_high,
			     u8 *rx,
			     int len)
{
	int ret;
	struct spi_transfer xfer[2] = {
		{
			.len = 1,
			.tx_buf = st->tx,
		}, {
			.len = len,
			.rx_buf = rx,
		}
	};

	st->tx[0] = SCA3000_READ_REG(reg_address_high);
	ret = spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
	if (ret) {
		dev_err(get_device(&st->us->dev), "problem reading register");
		return ret;
	}

	return 0;
}

/**
 * sca3000_ring_int_process() - ring specific interrupt handling.
 * @val: Value of the interrupt status register.
 * @indio_dev: Device instance specific IIO device structure.
 */
static void sca3000_ring_int_process(u8 val, struct iio_dev *indio_dev)
{
	struct sca3000_state *st = iio_priv(indio_dev);
	int ret, i, num_available;

	mutex_lock(&st->lock);

	if (val & SCA3000_REG_INT_STATUS_HALF) {
		ret = sca3000_read_data_short(st, SCA3000_REG_BUF_COUNT_ADDR,
					      1);
		if (ret)
			goto error_ret;
		num_available = st->rx[0];
		/*
		 * num_available is the total number of samples available
		 * i.e. number of time points * number of channels.
		 */
		ret = sca3000_read_data(st, SCA3000_REG_RING_OUT_ADDR, st->rx,
					num_available * 2);
		if (ret)
			goto error_ret;
		for (i = 0; i < num_available / 3; i++) {
			/*
			 * Dirty hack to cover for 11 bit in fifo, 13 bit
			 * direct reading.
			 *
			 * In theory the bottom two bits are undefined.
			 * In reality they appear to always be 0.
			 */
			iio_push_to_buffers(indio_dev, st->rx + i * 3 * 2);
		}
	}
error_ret:
	mutex_unlock(&st->lock);
}

/**
 * sca3000_event_handler() - handling ring and non ring events
 * @irq: The irq being handled.
 * @private: struct iio_device pointer for the device.
 *
 * Ring related interrupt handler. Depending on event, push to
 * the ring buffer event chrdev or the event one.
 *
 * This function is complicated by the fact that the devices can signify ring
 * and non ring events via the same interrupt line and they can only
 * be distinguished via a read of the relevant status register.
 */
static irqreturn_t sca3000_event_handler(int irq, void *private)
{
	struct iio_dev *indio_dev = private;
	struct sca3000_state *st = iio_priv(indio_dev);
	int ret, val;
	s64 last_timestamp = iio_get_time_ns(indio_dev);

	/*
	 * Could lead if badly timed to an extra read of status reg,
	 * but ensures no interrupt is missed.
	 */
	mutex_lock(&st->lock);
	ret = sca3000_read_data_short(st, SCA3000_REG_INT_STATUS_ADDR, 1);
	val = st->rx[0];
	mutex_unlock(&st->lock);
	if (ret)
		goto done;

	sca3000_ring_int_process(val, indio_dev);

	if (val & SCA3000_INT_STATUS_FREE_FALL)
		iio_push_event(indio_dev,
			       IIO_MOD_EVENT_CODE(IIO_ACCEL,
						  0,
						  IIO_MOD_X_AND_Y_AND_Z,
						  IIO_EV_TYPE_MAG,
						  IIO_EV_DIR_FALLING),
			       last_timestamp);

	if (val & SCA3000_INT_STATUS_Y_TRIGGER)
		iio_push_event(indio_dev,
			       IIO_MOD_EVENT_CODE(IIO_ACCEL,
						  0,
						  IIO_MOD_Y,
						  IIO_EV_TYPE_MAG,
						  IIO_EV_DIR_RISING),
			       last_timestamp);

	if (val & SCA3000_INT_STATUS_X_TRIGGER)
		iio_push_event(indio_dev,
			       IIO_MOD_EVENT_CODE(IIO_ACCEL,
						  0,
						  IIO_MOD_X,
						  IIO_EV_TYPE_MAG,
						  IIO_EV_DIR_RISING),
			       last_timestamp);

	if (val & SCA3000_INT_STATUS_Z_TRIGGER)
		iio_push_event(indio_dev,
			       IIO_MOD_EVENT_CODE(IIO_ACCEL,
						  0,
						  IIO_MOD_Z,
						  IIO_EV_TYPE_MAG,
						  IIO_EV_DIR_RISING),
			       last_timestamp);

done:
	return IRQ_HANDLED;
}

/**
 * sca3000_read_event_config() what events are enabled
 **/
static int sca3000_read_event_config(struct iio_dev *indio_dev,
				     const struct iio_chan_spec *chan,
				     enum iio_event_type type,
				     enum iio_event_direction dir)
{
	struct sca3000_state *st = iio_priv(indio_dev);
	int ret;
	/* read current value of mode register */
	mutex_lock(&st->lock);

	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
	if (ret)
		goto error_ret;

	switch (chan->channel2) {
	case IIO_MOD_X_AND_Y_AND_Z:
		ret = !!(st->rx[0] & SCA3000_REG_MODE_FREE_FALL_DETECT);
		break;
	case IIO_MOD_X:
	case IIO_MOD_Y:
	case IIO_MOD_Z:
		/*
		 * Motion detection mode cannot run at the same time as
		 * acceleration data being read.
		 */
		if ((st->rx[0] & SCA3000_REG_MODE_MODE_MASK)
		    != SCA3000_REG_MODE_MEAS_MODE_MOT_DET) {
			ret = 0;
		} else {
			ret = sca3000_read_ctrl_reg(st,
						SCA3000_REG_CTRL_SEL_MD_CTRL);
			if (ret < 0)
				goto error_ret;
			/* only supporting logical or's for now */
			ret = !!(ret & sca3000_addresses[chan->address][2]);
		}
		break;
	default:
		ret = -EINVAL;
	}

error_ret:
	mutex_unlock(&st->lock);

	return ret;
}

static int sca3000_freefall_set_state(struct iio_dev *indio_dev, int state)
{
	struct sca3000_state *st = iio_priv(indio_dev);
	int ret;

	/* read current value of mode register */
	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
	if (ret)
		return ret;

	/* if off and should be on */
	if (state && !(st->rx[0] & SCA3000_REG_MODE_FREE_FALL_DETECT))
		return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
					 st->rx[0] | SCA3000_REG_MODE_FREE_FALL_DETECT);
	/* if on and should be off */
	else if (!state && (st->rx[0] & SCA3000_REG_MODE_FREE_FALL_DETECT))
		return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
					 st->rx[0] & ~SCA3000_REG_MODE_FREE_FALL_DETECT);
	else
		return 0;
}

static int sca3000_motion_detect_set_state(struct iio_dev *indio_dev, int axis,
					   int state)
{
	struct sca3000_state *st = iio_priv(indio_dev);
	int ret, ctrlval;

	/*
	 * First read the motion detector config to find out if
	 * this axis is on
	 */
	ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_MD_CTRL);
	if (ret < 0)
		return ret;
	ctrlval = ret;
	/* if off and should be on */
	if (state && !(ctrlval & sca3000_addresses[axis][2])) {
		ret = sca3000_write_ctrl_reg(st,
					     SCA3000_REG_CTRL_SEL_MD_CTRL,
					     ctrlval |
					     sca3000_addresses[axis][2]);
		if (ret)
			return ret;
		st->mo_det_use_count++;
	} else if (!state && (ctrlval & sca3000_addresses[axis][2])) {
		ret = sca3000_write_ctrl_reg(st,
					     SCA3000_REG_CTRL_SEL_MD_CTRL,
					     ctrlval &
					     ~(sca3000_addresses[axis][2]));
		if (ret)
			return ret;
		st->mo_det_use_count--;
	}

	/* read current value of mode register */
	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
	if (ret)
		return ret;
	/* if off and should be on */
	if ((st->mo_det_use_count) &&
	    ((st->rx[0] & SCA3000_REG_MODE_MODE_MASK)
	     != SCA3000_REG_MODE_MEAS_MODE_MOT_DET))
		return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
			(st->rx[0] & ~SCA3000_REG_MODE_MODE_MASK)
			| SCA3000_REG_MODE_MEAS_MODE_MOT_DET);
	/* if on and should be off */
	else if (!(st->mo_det_use_count) &&
		 ((st->rx[0] & SCA3000_REG_MODE_MODE_MASK)
		  == SCA3000_REG_MODE_MEAS_MODE_MOT_DET))
		return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
			st->rx[0] & SCA3000_REG_MODE_MODE_MASK);
	else
		return 0;
}

/**
 * sca3000_write_event_config() - simple on off control for motion detector
 * @indio_dev: IIO device instance specific structure. Data specific to this
 * particular driver may be accessed via iio_priv(indio_dev).
 * @chan: Description of the channel whose event we are configuring.
 * @type: The type of event.
 * @dir: The direction of the event.
 * @state: Desired state of event being configured.
 *
 * This is a per axis control, but enabling any will result in the
 * motion detector unit being enabled.
 * N.B. enabling motion detector stops normal data acquisition.
 * There is a complexity in knowing which mode to return to when
 * this mode is disabled.  Currently normal mode is assumed.
 **/
static int sca3000_write_event_config(struct iio_dev *indio_dev,
				      const struct iio_chan_spec *chan,
				      enum iio_event_type type,
				      enum iio_event_direction dir,
				      int state)
{
	struct sca3000_state *st = iio_priv(indio_dev);
	int ret;

	mutex_lock(&st->lock);
	switch (chan->channel2) {
	case IIO_MOD_X_AND_Y_AND_Z:
		ret = sca3000_freefall_set_state(indio_dev, state);
		break;

	case IIO_MOD_X:
	case IIO_MOD_Y:
	case IIO_MOD_Z:
		ret = sca3000_motion_detect_set_state(indio_dev,
						      chan->address,
						      state);
		break;
	default:
		ret = -EINVAL;
		break;
	}
	mutex_unlock(&st->lock);

	return ret;
}

static int sca3000_configure_ring(struct iio_dev *indio_dev)
{
	struct iio_buffer *buffer;

	buffer = iio_kfifo_allocate();
	if (!buffer)
		return -ENOMEM;

	iio_device_attach_buffer(indio_dev, buffer);
	indio_dev->modes |= INDIO_BUFFER_SOFTWARE;

	return 0;
}

static void sca3000_unconfigure_ring(struct iio_dev *indio_dev)
{
	iio_kfifo_free(indio_dev->buffer);
}

static inline
int __sca3000_hw_ring_state_set(struct iio_dev *indio_dev, bool state)
{
	struct sca3000_state *st = iio_priv(indio_dev);
	int ret;

	mutex_lock(&st->lock);
	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
	if (ret)
		goto error_ret;
	if (state) {
		dev_info(&indio_dev->dev, "supposedly enabling ring buffer\n");
		ret = sca3000_write_reg(st,
			SCA3000_REG_MODE_ADDR,
			(st->rx[0] | SCA3000_REG_MODE_RING_BUF_ENABLE));
	} else
		ret = sca3000_write_reg(st,
			SCA3000_REG_MODE_ADDR,
			(st->rx[0] & ~SCA3000_REG_MODE_RING_BUF_ENABLE));
error_ret:
	mutex_unlock(&st->lock);

	return ret;
}

/**
 * sca3000_hw_ring_preenable() - hw ring buffer preenable function
 * @indio_dev: structure representing the IIO device. Device instance
 * specific state can be accessed via iio_priv(indio_dev).
 *
 * Very simple enable function as the chip will allows normal reads
 * during ring buffer operation so as long as it is indeed running
 * before we notify the core, the precise ordering does not matter.
 */
static int sca3000_hw_ring_preenable(struct iio_dev *indio_dev)
{
	int ret;
	struct sca3000_state *st = iio_priv(indio_dev);

	mutex_lock(&st->lock);

	/* Enable the 50% full interrupt */
	ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
	if (ret)
		goto error_unlock;
	ret = sca3000_write_reg(st,
				SCA3000_REG_INT_MASK_ADDR,
				st->rx[0] | SCA3000_REG_INT_MASK_RING_HALF);
	if (ret)
		goto error_unlock;

	mutex_unlock(&st->lock);

	return __sca3000_hw_ring_state_set(indio_dev, 1);

error_unlock:
	mutex_unlock(&st->lock);

	return ret;
}

static int sca3000_hw_ring_postdisable(struct iio_dev *indio_dev)
{
	int ret;
	struct sca3000_state *st = iio_priv(indio_dev);

	ret = __sca3000_hw_ring_state_set(indio_dev, 0);
	if (ret)
		return ret;

	/* Disable the 50% full interrupt */
	mutex_lock(&st->lock);

	ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
	if (ret)
		goto unlock;
	ret = sca3000_write_reg(st,
				SCA3000_REG_INT_MASK_ADDR,
				st->rx[0] & ~SCA3000_REG_INT_MASK_RING_HALF);
unlock:
	mutex_unlock(&st->lock);
	return ret;
}

static const struct iio_buffer_setup_ops sca3000_ring_setup_ops = {
	.preenable = &sca3000_hw_ring_preenable,
	.postdisable = &sca3000_hw_ring_postdisable,
};

/**
 * sca3000_clean_setup() - get the device into a predictable state
 * @st: Device instance specific private data structure
 *
 * Devices use flash memory to store many of the register values
 * and hence can come up in somewhat unpredictable states.
 * Hence reset everything on driver load.
 */
static int sca3000_clean_setup(struct sca3000_state *st)
{
	int ret;

	mutex_lock(&st->lock);
	/* Ensure all interrupts have been acknowledged */
	ret = sca3000_read_data_short(st, SCA3000_REG_INT_STATUS_ADDR, 1);
	if (ret)
		goto error_ret;

	/* Turn off all motion detection channels */
	ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_MD_CTRL);
	if (ret < 0)
		goto error_ret;
	ret = sca3000_write_ctrl_reg(st, SCA3000_REG_CTRL_SEL_MD_CTRL,
				     ret & SCA3000_MD_CTRL_PROT_MASK);
	if (ret)
		goto error_ret;

	/* Disable ring buffer */
	ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL);
	if (ret < 0)
		goto error_ret;
	ret = sca3000_write_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL,
				     (ret & SCA3000_REG_OUT_CTRL_PROT_MASK)
				     | SCA3000_REG_OUT_CTRL_BUF_X_EN
				     | SCA3000_REG_OUT_CTRL_BUF_Y_EN
				     | SCA3000_REG_OUT_CTRL_BUF_Z_EN
				     | SCA3000_REG_OUT_CTRL_BUF_DIV_4);
	if (ret)
		goto error_ret;
	/* Enable interrupts, relevant to mode and set up as active low */
	ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
	if (ret)
		goto error_ret;
	ret = sca3000_write_reg(st,
				SCA3000_REG_INT_MASK_ADDR,
				(ret & SCA3000_REG_INT_MASK_PROT_MASK)
				| SCA3000_REG_INT_MASK_ACTIVE_LOW);
	if (ret)
		goto error_ret;
	/*
	 * Select normal measurement mode, free fall off, ring off
	 * Ring in 12 bit mode - it is fine to overwrite reserved bits 3,5
	 * as that occurs in one of the example on the datasheet
	 */
	ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
	if (ret)
		goto error_ret;
	ret = sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
				(st->rx[0] & SCA3000_MODE_PROT_MASK));

error_ret:
	mutex_unlock(&st->lock);
	return ret;
}

static const struct iio_info sca3000_info = {
	.attrs = &sca3000_attribute_group,
	.read_raw = &sca3000_read_raw,
	.write_raw = &sca3000_write_raw,
	.read_event_value = &sca3000_read_event_value,
	.write_event_value = &sca3000_write_event_value,
	.read_event_config = &sca3000_read_event_config,
	.write_event_config = &sca3000_write_event_config,
};

static int sca3000_probe(struct spi_device *spi)
{
	int ret;
	struct sca3000_state *st;
	struct iio_dev *indio_dev;

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

	st = iio_priv(indio_dev);
	spi_set_drvdata(spi, indio_dev);
	st->us = spi;
	mutex_init(&st->lock);
	st->info = &sca3000_spi_chip_info_tbl[spi_get_device_id(spi)
					      ->driver_data];

	indio_dev->dev.parent = &spi->dev;
	indio_dev->name = spi_get_device_id(spi)->name;
	indio_dev->info = &sca3000_info;
	if (st->info->temp_output) {
		indio_dev->channels = sca3000_channels_with_temp;
		indio_dev->num_channels =
			ARRAY_SIZE(sca3000_channels_with_temp);
	} else {
		indio_dev->channels = sca3000_channels;
		indio_dev->num_channels = ARRAY_SIZE(sca3000_channels);
	}
	indio_dev->modes = INDIO_DIRECT_MODE;

	sca3000_configure_ring(indio_dev);

	if (spi->irq) {
		ret = request_threaded_irq(spi->irq,
					   NULL,
					   &sca3000_event_handler,
					   IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
					   "sca3000",
					   indio_dev);
		if (ret)
			return ret;
	}
	indio_dev->setup_ops = &sca3000_ring_setup_ops;
	ret = sca3000_clean_setup(st);
	if (ret)
		goto error_free_irq;

	ret = sca3000_print_rev(indio_dev);
	if (ret)
		goto error_free_irq;

	return iio_device_register(indio_dev);

error_free_irq:
	if (spi->irq)
		free_irq(spi->irq, indio_dev);

	return ret;
}

static int sca3000_stop_all_interrupts(struct sca3000_state *st)
{
	int ret;

	mutex_lock(&st->lock);
	ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
	if (ret)
		goto error_ret;
	ret = sca3000_write_reg(st, SCA3000_REG_INT_MASK_ADDR,
				(st->rx[0] &
				 ~(SCA3000_REG_INT_MASK_RING_THREE_QUARTER |
				   SCA3000_REG_INT_MASK_RING_HALF |
				   SCA3000_REG_INT_MASK_ALL_INTS)));
error_ret:
	mutex_unlock(&st->lock);
	return ret;
}

static int sca3000_remove(struct spi_device *spi)
{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);
	struct sca3000_state *st = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);

	/* Must ensure no interrupts can be generated after this! */
	sca3000_stop_all_interrupts(st);
	if (spi->irq)
		free_irq(spi->irq, indio_dev);

	sca3000_unconfigure_ring(indio_dev);

	return 0;
}

static const struct spi_device_id sca3000_id[] = {
	{"sca3000_d01", d01},
	{"sca3000_e02", e02},
	{"sca3000_e04", e04},
	{"sca3000_e05", e05},
	{}
};
MODULE_DEVICE_TABLE(spi, sca3000_id);

static struct spi_driver sca3000_driver = {
	.driver = {
		.name = "sca3000",
	},
	.probe = sca3000_probe,
	.remove = sca3000_remove,
	.id_table = sca3000_id,
};
module_spi_driver(sca3000_driver);

MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
MODULE_DESCRIPTION("VTI SCA3000 Series Accelerometers SPI driver");
MODULE_LICENSE("GPL v2");