summaryrefslogtreecommitdiffstats
path: root/drivers/iio/magnetometer/ak8975.c
blob: 43d08c089792c479042f7090a531be0f4d203e1b (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
/*
 * A sensor driver for the magnetometer AK8975.
 *
 * Magnetic compass sensor driver for monitoring magnetic flux information.
 *
 * Copyright (c) 2010, NVIDIA Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA	02110-1301, USA.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/acpi.h>
#include <linux/regulator/consumer.h>
#include <linux/pm_runtime.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>

#include <linux/iio/magnetometer/ak8975.h>

/*
 * Register definitions, as well as various shifts and masks to get at the
 * individual fields of the registers.
 */
#define AK8975_REG_WIA			0x00
#define AK8975_DEVICE_ID		0x48

#define AK8975_REG_INFO			0x01

#define AK8975_REG_ST1			0x02
#define AK8975_REG_ST1_DRDY_SHIFT	0
#define AK8975_REG_ST1_DRDY_MASK	(1 << AK8975_REG_ST1_DRDY_SHIFT)

#define AK8975_REG_HXL			0x03
#define AK8975_REG_HXH			0x04
#define AK8975_REG_HYL			0x05
#define AK8975_REG_HYH			0x06
#define AK8975_REG_HZL			0x07
#define AK8975_REG_HZH			0x08
#define AK8975_REG_ST2			0x09
#define AK8975_REG_ST2_DERR_SHIFT	2
#define AK8975_REG_ST2_DERR_MASK	(1 << AK8975_REG_ST2_DERR_SHIFT)

#define AK8975_REG_ST2_HOFL_SHIFT	3
#define AK8975_REG_ST2_HOFL_MASK	(1 << AK8975_REG_ST2_HOFL_SHIFT)

#define AK8975_REG_CNTL			0x0A
#define AK8975_REG_CNTL_MODE_SHIFT	0
#define AK8975_REG_CNTL_MODE_MASK	(0xF << AK8975_REG_CNTL_MODE_SHIFT)
#define AK8975_REG_CNTL_MODE_POWER_DOWN	0x00
#define AK8975_REG_CNTL_MODE_ONCE	0x01
#define AK8975_REG_CNTL_MODE_SELF_TEST	0x08
#define AK8975_REG_CNTL_MODE_FUSE_ROM	0x0F

#define AK8975_REG_RSVC			0x0B
#define AK8975_REG_ASTC			0x0C
#define AK8975_REG_TS1			0x0D
#define AK8975_REG_TS2			0x0E
#define AK8975_REG_I2CDIS		0x0F
#define AK8975_REG_ASAX			0x10
#define AK8975_REG_ASAY			0x11
#define AK8975_REG_ASAZ			0x12

#define AK8975_MAX_REGS			AK8975_REG_ASAZ

/*
 * AK09912 Register definitions
 */
#define AK09912_REG_WIA1		0x00
#define AK09912_REG_WIA2		0x01
#define AK09912_DEVICE_ID		0x04
#define AK09911_DEVICE_ID		0x05

#define AK09911_REG_INFO1		0x02
#define AK09911_REG_INFO2		0x03

#define AK09912_REG_ST1			0x10

#define AK09912_REG_ST1_DRDY_SHIFT	0
#define AK09912_REG_ST1_DRDY_MASK	(1 << AK09912_REG_ST1_DRDY_SHIFT)

#define AK09912_REG_HXL			0x11
#define AK09912_REG_HXH			0x12
#define AK09912_REG_HYL			0x13
#define AK09912_REG_HYH			0x14
#define AK09912_REG_HZL			0x15
#define AK09912_REG_HZH			0x16
#define AK09912_REG_TMPS		0x17

#define AK09912_REG_ST2			0x18
#define AK09912_REG_ST2_HOFL_SHIFT	3
#define AK09912_REG_ST2_HOFL_MASK	(1 << AK09912_REG_ST2_HOFL_SHIFT)

#define AK09912_REG_CNTL1		0x30

#define AK09912_REG_CNTL2		0x31
#define AK09912_REG_CNTL_MODE_POWER_DOWN	0x00
#define AK09912_REG_CNTL_MODE_ONCE	0x01
#define AK09912_REG_CNTL_MODE_SELF_TEST	0x10
#define AK09912_REG_CNTL_MODE_FUSE_ROM	0x1F
#define AK09912_REG_CNTL2_MODE_SHIFT	0
#define AK09912_REG_CNTL2_MODE_MASK	(0x1F << AK09912_REG_CNTL2_MODE_SHIFT)

#define AK09912_REG_CNTL3		0x32

#define AK09912_REG_TS1			0x33
#define AK09912_REG_TS2			0x34
#define AK09912_REG_TS3			0x35
#define AK09912_REG_I2CDIS		0x36
#define AK09912_REG_TS4			0x37

#define AK09912_REG_ASAX		0x60
#define AK09912_REG_ASAY		0x61
#define AK09912_REG_ASAZ		0x62

#define AK09912_MAX_REGS		AK09912_REG_ASAZ

/*
 * Miscellaneous values.
 */
#define AK8975_MAX_CONVERSION_TIMEOUT	500
#define AK8975_CONVERSION_DONE_POLL_TIME 10
#define AK8975_DATA_READY_TIMEOUT	((100*HZ)/1000)

/*
 * Precalculate scale factor (in Gauss units) for each axis and
 * store in the device data.
 *
 * This scale factor is axis-dependent, and is derived from 3 calibration
 * factors ASA(x), ASA(y), and ASA(z).
 *
 * These ASA values are read from the sensor device at start of day, and
 * cached in the device context struct.
 *
 * Adjusting the flux value with the sensitivity adjustment value should be
 * done via the following formula:
 *
 * Hadj = H * ( ( ( (ASA-128)*0.5 ) / 128 ) + 1 )
 * where H is the raw value, ASA is the sensitivity adjustment, and Hadj
 * is the resultant adjusted value.
 *
 * We reduce the formula to:
 *
 * Hadj = H * (ASA + 128) / 256
 *
 * H is in the range of -4096 to 4095.  The magnetometer has a range of
 * +-1229uT.  To go from the raw value to uT is:
 *
 * HuT = H * 1229/4096, or roughly, 3/10.
 *
 * Since 1uT = 0.01 gauss, our final scale factor becomes:
 *
 * Hadj = H * ((ASA + 128) / 256) * 3/10 * 1/100
 * Hadj = H * ((ASA + 128) * 0.003) / 256
 *
 * Since ASA doesn't change, we cache the resultant scale factor into the
 * device context in ak8975_setup().
 *
 * Given we use IIO_VAL_INT_PLUS_MICRO bit when displaying the scale, we
 * multiply the stored scale value by 1e6.
 */
static long ak8975_raw_to_gauss(u16 data)
{
	return (((long)data + 128) * 3000) / 256;
}

/*
 * For AK8963 and AK09911, same calculation, but the device is less sensitive:
 *
 * H is in the range of +-8190.  The magnetometer has a range of
 * +-4912uT.  To go from the raw value to uT is:
 *
 * HuT = H * 4912/8190, or roughly, 6/10, instead of 3/10.
 */

static long ak8963_09911_raw_to_gauss(u16 data)
{
	return (((long)data + 128) * 6000) / 256;
}

/*
 * For AK09912, same calculation, except the device is more sensitive:
 *
 * H is in the range of -32752 to 32752.  The magnetometer has a range of
 * +-4912uT.  To go from the raw value to uT is:
 *
 * HuT = H * 4912/32752, or roughly, 3/20, instead of 3/10.
 */
static long ak09912_raw_to_gauss(u16 data)
{
	return (((long)data + 128) * 1500) / 256;
}

/* Compatible Asahi Kasei Compass parts */
enum asahi_compass_chipset {
	AK8975,
	AK8963,
	AK09911,
	AK09912,
	AK_MAX_TYPE
};

enum ak_ctrl_reg_addr {
	ST1,
	ST2,
	CNTL,
	ASA_BASE,
	MAX_REGS,
	REGS_END,
};

enum ak_ctrl_reg_mask {
	ST1_DRDY,
	ST2_HOFL,
	ST2_DERR,
	CNTL_MODE,
	MASK_END,
};

enum ak_ctrl_mode {
	POWER_DOWN,
	MODE_ONCE,
	SELF_TEST,
	FUSE_ROM,
	MODE_END,
};

struct ak_def {
	enum asahi_compass_chipset type;
	long (*raw_to_gauss)(u16 data);
	u16 range;
	u8 ctrl_regs[REGS_END];
	u8 ctrl_masks[MASK_END];
	u8 ctrl_modes[MODE_END];
	u8 data_regs[3];
};

static const struct ak_def ak_def_array[AK_MAX_TYPE] = {
	{
		.type = AK8975,
		.raw_to_gauss = ak8975_raw_to_gauss,
		.range = 4096,
		.ctrl_regs = {
			AK8975_REG_ST1,
			AK8975_REG_ST2,
			AK8975_REG_CNTL,
			AK8975_REG_ASAX,
			AK8975_MAX_REGS},
		.ctrl_masks = {
			AK8975_REG_ST1_DRDY_MASK,
			AK8975_REG_ST2_HOFL_MASK,
			AK8975_REG_ST2_DERR_MASK,
			AK8975_REG_CNTL_MODE_MASK},
		.ctrl_modes = {
			AK8975_REG_CNTL_MODE_POWER_DOWN,
			AK8975_REG_CNTL_MODE_ONCE,
			AK8975_REG_CNTL_MODE_SELF_TEST,
			AK8975_REG_CNTL_MODE_FUSE_ROM},
		.data_regs = {
			AK8975_REG_HXL,
			AK8975_REG_HYL,
			AK8975_REG_HZL},
	},
	{
		.type = AK8963,
		.raw_to_gauss = ak8963_09911_raw_to_gauss,
		.range = 8190,
		.ctrl_regs = {
			AK8975_REG_ST1,
			AK8975_REG_ST2,
			AK8975_REG_CNTL,
			AK8975_REG_ASAX,
			AK8975_MAX_REGS},
		.ctrl_masks = {
			AK8975_REG_ST1_DRDY_MASK,
			AK8975_REG_ST2_HOFL_MASK,
			0,
			AK8975_REG_CNTL_MODE_MASK},
		.ctrl_modes = {
			AK8975_REG_CNTL_MODE_POWER_DOWN,
			AK8975_REG_CNTL_MODE_ONCE,
			AK8975_REG_CNTL_MODE_SELF_TEST,
			AK8975_REG_CNTL_MODE_FUSE_ROM},
		.data_regs = {
			AK8975_REG_HXL,
			AK8975_REG_HYL,
			AK8975_REG_HZL},
	},
	{
		.type = AK09911,
		.raw_to_gauss = ak8963_09911_raw_to_gauss,
		.range = 8192,
		.ctrl_regs = {
			AK09912_REG_ST1,
			AK09912_REG_ST2,
			AK09912_REG_CNTL2,
			AK09912_REG_ASAX,
			AK09912_MAX_REGS},
		.ctrl_masks = {
			AK09912_REG_ST1_DRDY_MASK,
			AK09912_REG_ST2_HOFL_MASK,
			0,
			AK09912_REG_CNTL2_MODE_MASK},
		.ctrl_modes = {
			AK09912_REG_CNTL_MODE_POWER_DOWN,
			AK09912_REG_CNTL_MODE_ONCE,
			AK09912_REG_CNTL_MODE_SELF_TEST,
			AK09912_REG_CNTL_MODE_FUSE_ROM},
		.data_regs = {
			AK09912_REG_HXL,
			AK09912_REG_HYL,
			AK09912_REG_HZL},
	},
	{
		.type = AK09912,
		.raw_to_gauss = ak09912_raw_to_gauss,
		.range = 32752,
		.ctrl_regs = {
			AK09912_REG_ST1,
			AK09912_REG_ST2,
			AK09912_REG_CNTL2,
			AK09912_REG_ASAX,
			AK09912_MAX_REGS},
		.ctrl_masks = {
			AK09912_REG_ST1_DRDY_MASK,
			AK09912_REG_ST2_HOFL_MASK,
			0,
			AK09912_REG_CNTL2_MODE_MASK},
		.ctrl_modes = {
			AK09912_REG_CNTL_MODE_POWER_DOWN,
			AK09912_REG_CNTL_MODE_ONCE,
			AK09912_REG_CNTL_MODE_SELF_TEST,
			AK09912_REG_CNTL_MODE_FUSE_ROM},
		.data_regs = {
			AK09912_REG_HXL,
			AK09912_REG_HYL,
			AK09912_REG_HZL},
	}
};

/*
 * Per-instance context data for the device.
 */
struct ak8975_data {
	struct i2c_client	*client;
	const struct ak_def	*def;
	struct mutex		lock;
	u8			asa[3];
	long			raw_to_gauss[3];
	int			eoc_gpio;
	int			eoc_irq;
	wait_queue_head_t	data_ready_queue;
	unsigned long		flags;
	u8			cntl_cache;
	struct iio_mount_matrix orientation;
	struct regulator	*vdd;
	struct regulator	*vid;
};

/* Enable attached power regulator if any. */
static int ak8975_power_on(const struct ak8975_data *data)
{
	int ret;

	ret = regulator_enable(data->vdd);
	if (ret) {
		dev_warn(&data->client->dev,
			 "Failed to enable specified Vdd supply\n");
		return ret;
	}
	ret = regulator_enable(data->vid);
	if (ret) {
		dev_warn(&data->client->dev,
			 "Failed to enable specified Vid supply\n");
		return ret;
	}
	/*
	 * According to the datasheet the power supply rise time i 200us
	 * and the minimum wait time before mode setting is 100us, in
	 * total 300 us. Add some margin and say minimum 500us here.
	 */
	usleep_range(500, 1000);
	return 0;
}

/* Disable attached power regulator if any. */
static void ak8975_power_off(const struct ak8975_data *data)
{
	regulator_disable(data->vid);
	regulator_disable(data->vdd);
}

/*
 * Return 0 if the i2c device is the one we expect.
 * return a negative error number otherwise
 */
static int ak8975_who_i_am(struct i2c_client *client,
			   enum asahi_compass_chipset type)
{
	u8 wia_val[2];
	int ret;

	/*
	 * Signature for each device:
	 * Device   |  WIA1      |  WIA2
	 * AK09912  |  DEVICE_ID |  AK09912_DEVICE_ID
	 * AK09911  |  DEVICE_ID |  AK09911_DEVICE_ID
	 * AK8975   |  DEVICE_ID |  NA
	 * AK8963   |  DEVICE_ID |  NA
	 */
	ret = i2c_smbus_read_i2c_block_data_or_emulated(
			client, AK09912_REG_WIA1, 2, wia_val);
	if (ret < 0) {
		dev_err(&client->dev, "Error reading WIA\n");
		return ret;
	}

	if (wia_val[0] != AK8975_DEVICE_ID)
		return -ENODEV;

	switch (type) {
	case AK8975:
	case AK8963:
		return 0;
	case AK09911:
		if (wia_val[1] == AK09911_DEVICE_ID)
			return 0;
		break;
	case AK09912:
		if (wia_val[1] == AK09912_DEVICE_ID)
			return 0;
		break;
	default:
		dev_err(&client->dev, "Type %d unknown\n", type);
	}
	return -ENODEV;
}

/*
 * Helper function to write to CNTL register.
 */
static int ak8975_set_mode(struct ak8975_data *data, enum ak_ctrl_mode mode)
{
	u8 regval;
	int ret;

	regval = (data->cntl_cache & ~data->def->ctrl_masks[CNTL_MODE]) |
		 data->def->ctrl_modes[mode];
	ret = i2c_smbus_write_byte_data(data->client,
					data->def->ctrl_regs[CNTL], regval);
	if (ret < 0) {
		return ret;
	}
	data->cntl_cache = regval;
	/* After mode change wait atleast 100us */
	usleep_range(100, 500);

	return 0;
}

/*
 * Handle data ready irq
 */
static irqreturn_t ak8975_irq_handler(int irq, void *data)
{
	struct ak8975_data *ak8975 = data;

	set_bit(0, &ak8975->flags);
	wake_up(&ak8975->data_ready_queue);

	return IRQ_HANDLED;
}

/*
 * Install data ready interrupt handler
 */
static int ak8975_setup_irq(struct ak8975_data *data)
{
	struct i2c_client *client = data->client;
	int rc;
	int irq;

	init_waitqueue_head(&data->data_ready_queue);
	clear_bit(0, &data->flags);
	if (client->irq)
		irq = client->irq;
	else
		irq = gpio_to_irq(data->eoc_gpio);

	rc = devm_request_irq(&client->dev, irq, ak8975_irq_handler,
			      IRQF_TRIGGER_RISING | IRQF_ONESHOT,
			      dev_name(&client->dev), data);
	if (rc < 0) {
		dev_err(&client->dev,
			"irq %d request failed, (gpio %d): %d\n",
			irq, data->eoc_gpio, rc);
		return rc;
	}

	data->eoc_irq = irq;

	return rc;
}


/*
 * Perform some start-of-day setup, including reading the asa calibration
 * values and caching them.
 */
static int ak8975_setup(struct i2c_client *client)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct ak8975_data *data = iio_priv(indio_dev);
	int ret;

	/* Write the fused rom access mode. */
	ret = ak8975_set_mode(data, FUSE_ROM);
	if (ret < 0) {
		dev_err(&client->dev, "Error in setting fuse access mode\n");
		return ret;
	}

	/* Get asa data and store in the device data. */
	ret = i2c_smbus_read_i2c_block_data_or_emulated(
			client, data->def->ctrl_regs[ASA_BASE],
			3, data->asa);
	if (ret < 0) {
		dev_err(&client->dev, "Not able to read asa data\n");
		return ret;
	}

	/* After reading fuse ROM data set power-down mode */
	ret = ak8975_set_mode(data, POWER_DOWN);
	if (ret < 0) {
		dev_err(&client->dev, "Error in setting power-down mode\n");
		return ret;
	}

	if (data->eoc_gpio > 0 || client->irq > 0) {
		ret = ak8975_setup_irq(data);
		if (ret < 0) {
			dev_err(&client->dev,
				"Error setting data ready interrupt\n");
			return ret;
		}
	}

	data->raw_to_gauss[0] = data->def->raw_to_gauss(data->asa[0]);
	data->raw_to_gauss[1] = data->def->raw_to_gauss(data->asa[1]);
	data->raw_to_gauss[2] = data->def->raw_to_gauss(data->asa[2]);

	return 0;
}

static int wait_conversion_complete_gpio(struct ak8975_data *data)
{
	struct i2c_client *client = data->client;
	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
	int ret;

	/* Wait for the conversion to complete. */
	while (timeout_ms) {
		msleep(AK8975_CONVERSION_DONE_POLL_TIME);
		if (gpio_get_value(data->eoc_gpio))
			break;
		timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
	}
	if (!timeout_ms) {
		dev_err(&client->dev, "Conversion timeout happened\n");
		return -EINVAL;
	}

	ret = i2c_smbus_read_byte_data(client, data->def->ctrl_regs[ST1]);
	if (ret < 0)
		dev_err(&client->dev, "Error in reading ST1\n");

	return ret;
}

static int wait_conversion_complete_polled(struct ak8975_data *data)
{
	struct i2c_client *client = data->client;
	u8 read_status;
	u32 timeout_ms = AK8975_MAX_CONVERSION_TIMEOUT;
	int ret;

	/* Wait for the conversion to complete. */
	while (timeout_ms) {
		msleep(AK8975_CONVERSION_DONE_POLL_TIME);
		ret = i2c_smbus_read_byte_data(client,
					       data->def->ctrl_regs[ST1]);
		if (ret < 0) {
			dev_err(&client->dev, "Error in reading ST1\n");
			return ret;
		}
		read_status = ret;
		if (read_status)
			break;
		timeout_ms -= AK8975_CONVERSION_DONE_POLL_TIME;
	}
	if (!timeout_ms) {
		dev_err(&client->dev, "Conversion timeout happened\n");
		return -EINVAL;
	}

	return read_status;
}

/* Returns 0 if the end of conversion interrupt occured or -ETIME otherwise */
static int wait_conversion_complete_interrupt(struct ak8975_data *data)
{
	int ret;

	ret = wait_event_timeout(data->data_ready_queue,
				 test_bit(0, &data->flags),
				 AK8975_DATA_READY_TIMEOUT);
	clear_bit(0, &data->flags);

	return ret > 0 ? 0 : -ETIME;
}

static int ak8975_start_read_axis(struct ak8975_data *data,
				  const struct i2c_client *client)
{
	/* Set up the device for taking a sample. */
	int ret = ak8975_set_mode(data, MODE_ONCE);

	if (ret < 0) {
		dev_err(&client->dev, "Error in setting operating mode\n");
		return ret;
	}

	/* Wait for the conversion to complete. */
	if (data->eoc_irq)
		ret = wait_conversion_complete_interrupt(data);
	else if (gpio_is_valid(data->eoc_gpio))
		ret = wait_conversion_complete_gpio(data);
	else
		ret = wait_conversion_complete_polled(data);
	if (ret < 0)
		return ret;

	/* This will be executed only for non-interrupt based waiting case */
	if (ret & data->def->ctrl_masks[ST1_DRDY]) {
		ret = i2c_smbus_read_byte_data(client,
					       data->def->ctrl_regs[ST2]);
		if (ret < 0) {
			dev_err(&client->dev, "Error in reading ST2\n");
			return ret;
		}
		if (ret & (data->def->ctrl_masks[ST2_DERR] |
			   data->def->ctrl_masks[ST2_HOFL])) {
			dev_err(&client->dev, "ST2 status error 0x%x\n", ret);
			return -EINVAL;
		}
	}

	return 0;
}

/* Retrieve raw flux value for one of the x, y, or z axis.  */
static int ak8975_read_axis(struct iio_dev *indio_dev, int index, int *val)
{
	struct ak8975_data *data = iio_priv(indio_dev);
	const struct i2c_client *client = data->client;
	const struct ak_def *def = data->def;
	__le16 rval;
	u16 buff;
	int ret;

	pm_runtime_get_sync(&data->client->dev);

	mutex_lock(&data->lock);

	ret = ak8975_start_read_axis(data, client);
	if (ret)
		goto exit;

	ret = i2c_smbus_read_i2c_block_data_or_emulated(
			client, def->data_regs[index],
			sizeof(rval), (u8*)&rval);
	if (ret < 0)
		goto exit;

	mutex_unlock(&data->lock);

	pm_runtime_mark_last_busy(&data->client->dev);
	pm_runtime_put_autosuspend(&data->client->dev);

	/* Swap bytes and convert to valid range. */
	buff = le16_to_cpu(rval);
	*val = clamp_t(s16, buff, -def->range, def->range);
	return IIO_VAL_INT;

exit:
	mutex_unlock(&data->lock);
	dev_err(&client->dev, "Error in reading axis\n");
	return ret;
}

static int ak8975_read_raw(struct iio_dev *indio_dev,
			   struct iio_chan_spec const *chan,
			   int *val, int *val2,
			   long mask)
{
	struct ak8975_data *data = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		return ak8975_read_axis(indio_dev, chan->address, val);
	case IIO_CHAN_INFO_SCALE:
		*val = 0;
		*val2 = data->raw_to_gauss[chan->address];
		return IIO_VAL_INT_PLUS_MICRO;
	}
	return -EINVAL;
}

static const struct iio_mount_matrix *
ak8975_get_mount_matrix(const struct iio_dev *indio_dev,
			const struct iio_chan_spec *chan)
{
	struct ak8975_data *data = iio_priv(indio_dev);

	return &data->orientation;
}

static const struct iio_chan_spec_ext_info ak8975_ext_info[] = {
	IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, ak8975_get_mount_matrix),
	{ }
};

#define AK8975_CHANNEL(axis, index)					\
	{								\
		.type = IIO_MAGN,					\
		.modified = 1,						\
		.channel2 = IIO_MOD_##axis,				\
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
			     BIT(IIO_CHAN_INFO_SCALE),			\
		.address = index,					\
		.scan_index = index,					\
		.scan_type = {						\
			.sign = 's',					\
			.realbits = 16,					\
			.storagebits = 16,				\
			.endianness = IIO_CPU				\
		},							\
		.ext_info = ak8975_ext_info,				\
	}

static const struct iio_chan_spec ak8975_channels[] = {
	AK8975_CHANNEL(X, 0), AK8975_CHANNEL(Y, 1), AK8975_CHANNEL(Z, 2),
	IIO_CHAN_SOFT_TIMESTAMP(3),
};

static const unsigned long ak8975_scan_masks[] = { 0x7, 0 };

static const struct iio_info ak8975_info = {
	.read_raw = &ak8975_read_raw,
};

#ifdef CONFIG_ACPI
static const struct acpi_device_id ak_acpi_match[] = {
	{"AK8975", AK8975},
	{"AK8963", AK8963},
	{"INVN6500", AK8963},
	{"AK009911", AK09911},
	{"AK09911", AK09911},
	{"AKM9911", AK09911},
	{"AK09912", AK09912},
	{ }
};
MODULE_DEVICE_TABLE(acpi, ak_acpi_match);
#endif

static const char *ak8975_match_acpi_device(struct device *dev,
					    enum asahi_compass_chipset *chipset)
{
	const struct acpi_device_id *id;

	id = acpi_match_device(dev->driver->acpi_match_table, dev);
	if (!id)
		return NULL;
	*chipset = (int)id->driver_data;

	return dev_name(dev);
}

static void ak8975_fill_buffer(struct iio_dev *indio_dev)
{
	struct ak8975_data *data = iio_priv(indio_dev);
	const struct i2c_client *client = data->client;
	const struct ak_def *def = data->def;
	int ret;
	s16 buff[8]; /* 3 x 16 bits axis values + 1 aligned 64 bits timestamp */
	__le16 fval[3];

	mutex_lock(&data->lock);

	ret = ak8975_start_read_axis(data, client);
	if (ret)
		goto unlock;

	/*
	 * For each axis, read the flux value from the appropriate register
	 * (the register is specified in the iio device attributes).
	 */
	ret = i2c_smbus_read_i2c_block_data_or_emulated(client,
							def->data_regs[0],
							3 * sizeof(fval[0]),
							(u8 *)fval);
	if (ret < 0)
		goto unlock;

	mutex_unlock(&data->lock);

	/* Clamp to valid range. */
	buff[0] = clamp_t(s16, le16_to_cpu(fval[0]), -def->range, def->range);
	buff[1] = clamp_t(s16, le16_to_cpu(fval[1]), -def->range, def->range);
	buff[2] = clamp_t(s16, le16_to_cpu(fval[2]), -def->range, def->range);

	iio_push_to_buffers_with_timestamp(indio_dev, buff,
					   iio_get_time_ns(indio_dev));
	return;

unlock:
	mutex_unlock(&data->lock);
	dev_err(&client->dev, "Error in reading axes block\n");
}

static irqreturn_t ak8975_handle_trigger(int irq, void *p)
{
	const struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;

	ak8975_fill_buffer(indio_dev);
	iio_trigger_notify_done(indio_dev->trig);
	return IRQ_HANDLED;
}

static int ak8975_probe(struct i2c_client *client,
			const struct i2c_device_id *id)
{
	struct ak8975_data *data;
	struct iio_dev *indio_dev;
	int eoc_gpio;
	int err;
	const char *name = NULL;
	enum asahi_compass_chipset chipset = AK_MAX_TYPE;
	const struct ak8975_platform_data *pdata =
		dev_get_platdata(&client->dev);

	/* Grab and set up the supplied GPIO. */
	if (pdata)
		eoc_gpio = pdata->eoc_gpio;
	else if (client->dev.of_node)
		eoc_gpio = of_get_gpio(client->dev.of_node, 0);
	else
		eoc_gpio = -1;

	if (eoc_gpio == -EPROBE_DEFER)
		return -EPROBE_DEFER;

	/* We may not have a GPIO based IRQ to scan, that is fine, we will
	   poll if so */
	if (gpio_is_valid(eoc_gpio)) {
		err = devm_gpio_request_one(&client->dev, eoc_gpio,
							GPIOF_IN, "ak_8975");
		if (err < 0) {
			dev_err(&client->dev,
				"failed to request GPIO %d, error %d\n",
							eoc_gpio, err);
			return err;
		}
	}

	/* Register with IIO */
	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
	if (indio_dev == NULL)
		return -ENOMEM;

	data = iio_priv(indio_dev);
	i2c_set_clientdata(client, indio_dev);

	data->client = client;
	data->eoc_gpio = eoc_gpio;
	data->eoc_irq = 0;

	if (!pdata) {
		err = iio_read_mount_matrix(&client->dev, "mount-matrix",
					    &data->orientation);
		if (err)
			return err;
	} else
		data->orientation = pdata->orientation;

	/* id will be NULL when enumerated via ACPI */
	if (id) {
		chipset = (enum asahi_compass_chipset)(id->driver_data);
		name = id->name;
	} else if (ACPI_HANDLE(&client->dev)) {
		name = ak8975_match_acpi_device(&client->dev, &chipset);
		if (!name)
			return -ENODEV;
	} else
		return -ENOSYS;

	if (chipset >= AK_MAX_TYPE) {
		dev_err(&client->dev, "AKM device type unsupported: %d\n",
			chipset);
		return -ENODEV;
	}

	data->def = &ak_def_array[chipset];

	/* Fetch the regulators */
	data->vdd = devm_regulator_get(&client->dev, "vdd");
	if (IS_ERR(data->vdd))
		return PTR_ERR(data->vdd);
	data->vid = devm_regulator_get(&client->dev, "vid");
	if (IS_ERR(data->vid))
		return PTR_ERR(data->vid);

	err = ak8975_power_on(data);
	if (err)
		return err;

	err = ak8975_who_i_am(client, data->def->type);
	if (err < 0) {
		dev_err(&client->dev, "Unexpected device\n");
		goto power_off;
	}
	dev_dbg(&client->dev, "Asahi compass chip %s\n", name);

	/* Perform some basic start-of-day setup of the device. */
	err = ak8975_setup(client);
	if (err < 0) {
		dev_err(&client->dev, "%s initialization fails\n", name);
		goto power_off;
	}

	mutex_init(&data->lock);
	indio_dev->dev.parent = &client->dev;
	indio_dev->channels = ak8975_channels;
	indio_dev->num_channels = ARRAY_SIZE(ak8975_channels);
	indio_dev->info = &ak8975_info;
	indio_dev->available_scan_masks = ak8975_scan_masks;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->name = name;

	err = iio_triggered_buffer_setup(indio_dev, NULL, ak8975_handle_trigger,
					 NULL);
	if (err) {
		dev_err(&client->dev, "triggered buffer setup failed\n");
		goto power_off;
	}

	err = iio_device_register(indio_dev);
	if (err) {
		dev_err(&client->dev, "device register failed\n");
		goto cleanup_buffer;
	}

	/* Enable runtime PM */
	pm_runtime_get_noresume(&client->dev);
	pm_runtime_set_active(&client->dev);
	pm_runtime_enable(&client->dev);
	/*
	 * The device comes online in 500us, so add two orders of magnitude
	 * of delay before autosuspending: 50 ms.
	 */
	pm_runtime_set_autosuspend_delay(&client->dev, 50);
	pm_runtime_use_autosuspend(&client->dev);
	pm_runtime_put(&client->dev);

	return 0;

cleanup_buffer:
	iio_triggered_buffer_cleanup(indio_dev);
power_off:
	ak8975_power_off(data);
	return err;
}

static int ak8975_remove(struct i2c_client *client)
{
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct ak8975_data *data = iio_priv(indio_dev);

	pm_runtime_get_sync(&client->dev);
	pm_runtime_put_noidle(&client->dev);
	pm_runtime_disable(&client->dev);
	iio_device_unregister(indio_dev);
	iio_triggered_buffer_cleanup(indio_dev);
	ak8975_set_mode(data, POWER_DOWN);
	ak8975_power_off(data);

	return 0;
}

#ifdef CONFIG_PM
static int ak8975_runtime_suspend(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct ak8975_data *data = iio_priv(indio_dev);
	int ret;

	/* Set the device in power down if it wasn't already */
	ret = ak8975_set_mode(data, POWER_DOWN);
	if (ret < 0) {
		dev_err(&client->dev, "Error in setting power-down mode\n");
		return ret;
	}
	/* Next cut the regulators */
	ak8975_power_off(data);

	return 0;
}

static int ak8975_runtime_resume(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct iio_dev *indio_dev = i2c_get_clientdata(client);
	struct ak8975_data *data = iio_priv(indio_dev);
	int ret;

	/* Take up the regulators */
	ak8975_power_on(data);
	/*
	 * We come up in powered down mode, the reading routines will
	 * put us in the mode to read values later.
	 */
	ret = ak8975_set_mode(data, POWER_DOWN);
	if (ret < 0) {
		dev_err(&client->dev, "Error in setting power-down mode\n");
		return ret;
	}

	return 0;
}
#endif /* CONFIG_PM */

static const struct dev_pm_ops ak8975_dev_pm_ops = {
	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
				pm_runtime_force_resume)
	SET_RUNTIME_PM_OPS(ak8975_runtime_suspend,
			   ak8975_runtime_resume, NULL)
};

static const struct i2c_device_id ak8975_id[] = {
	{"ak8975", AK8975},
	{"ak8963", AK8963},
	{"AK8963", AK8963},
	{"ak09911", AK09911},
	{"ak09912", AK09912},
	{}
};

MODULE_DEVICE_TABLE(i2c, ak8975_id);

static const struct of_device_id ak8975_of_match[] = {
	{ .compatible = "asahi-kasei,ak8975", },
	{ .compatible = "ak8975", },
	{ .compatible = "asahi-kasei,ak8963", },
	{ .compatible = "ak8963", },
	{ .compatible = "asahi-kasei,ak09911", },
	{ .compatible = "ak09911", },
	{ .compatible = "asahi-kasei,ak09912", },
	{ .compatible = "ak09912", },
	{}
};
MODULE_DEVICE_TABLE(of, ak8975_of_match);

static struct i2c_driver ak8975_driver = {
	.driver = {
		.name	= "ak8975",
		.pm = &ak8975_dev_pm_ops,
		.of_match_table = of_match_ptr(ak8975_of_match),
		.acpi_match_table = ACPI_PTR(ak_acpi_match),
	},
	.probe		= ak8975_probe,
	.remove		= ak8975_remove,
	.id_table	= ak8975_id,
};
module_i2c_driver(ak8975_driver);

MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_DESCRIPTION("AK8975 magnetometer driver");
MODULE_LICENSE("GPL");