Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: ac5d945be88a8ea9eab02b85b23a0bb84e11b93e (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
// SPDX-License-Identifier: GPL-2.0
/*
 * nvmem framework core.
 *
 * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
 * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com>
 */

#include <linux/device.h>
#include <linux/export.h>
#include <linux/fs.h>
#include <linux/idr.h>
#include <linux/init.h>
#include <linux/kref.h>
#include <linux/module.h>
#include <linux/nvmem-consumer.h>
#include <linux/nvmem-provider.h>
#include <linux/of.h>
#include <linux/slab.h>
#include "nvmem.h"

struct nvmem_cell {
	const char		*name;
	int			offset;
	int			bytes;
	int			bit_offset;
	int			nbits;
	struct device_node	*np;
	struct nvmem_device	*nvmem;
	struct list_head	node;
};

static DEFINE_MUTEX(nvmem_mutex);
static DEFINE_IDA(nvmem_ida);

static DEFINE_MUTEX(nvmem_cell_mutex);
static LIST_HEAD(nvmem_cell_tables);

static DEFINE_MUTEX(nvmem_lookup_mutex);
static LIST_HEAD(nvmem_lookup_list);

static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);


static int nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
			  void *val, size_t bytes)
{
	if (nvmem->reg_read)
		return nvmem->reg_read(nvmem->priv, offset, val, bytes);

	return -EINVAL;
}

static int nvmem_reg_write(struct nvmem_device *nvmem, unsigned int offset,
			   void *val, size_t bytes)
{
	if (nvmem->reg_write)
		return nvmem->reg_write(nvmem->priv, offset, val, bytes);

	return -EINVAL;
}

static void nvmem_release(struct device *dev)
{
	struct nvmem_device *nvmem = to_nvmem_device(dev);

	ida_simple_remove(&nvmem_ida, nvmem->id);
	kfree(nvmem);
}

static const struct device_type nvmem_provider_type = {
	.release	= nvmem_release,
};

static struct bus_type nvmem_bus_type = {
	.name		= "nvmem",
};

static int of_nvmem_match(struct device *dev, const void *nvmem_np)
{
	return dev->of_node == nvmem_np;
}

static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np)
{
	struct device *d;

	if (!nvmem_np)
		return NULL;

	d = bus_find_device(&nvmem_bus_type, NULL, nvmem_np, of_nvmem_match);

	if (!d)
		return NULL;

	return to_nvmem_device(d);
}

static struct nvmem_device *nvmem_find(const char *name)
{
	struct device *d;

	d = bus_find_device_by_name(&nvmem_bus_type, NULL, name);

	if (!d)
		return NULL;

	return to_nvmem_device(d);
}

static void nvmem_cell_drop(struct nvmem_cell *cell)
{
	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_REMOVE, cell);
	mutex_lock(&nvmem_mutex);
	list_del(&cell->node);
	mutex_unlock(&nvmem_mutex);
	of_node_put(cell->np);
	kfree(cell->name);
	kfree(cell);
}

static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem)
{
	struct nvmem_cell *cell, *p;

	list_for_each_entry_safe(cell, p, &nvmem->cells, node)
		nvmem_cell_drop(cell);
}

static void nvmem_cell_add(struct nvmem_cell *cell)
{
	mutex_lock(&nvmem_mutex);
	list_add_tail(&cell->node, &cell->nvmem->cells);
	mutex_unlock(&nvmem_mutex);
	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_CELL_ADD, cell);
}

static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem,
				   const struct nvmem_cell_info *info,
				   struct nvmem_cell *cell)
{
	cell->nvmem = nvmem;
	cell->offset = info->offset;
	cell->bytes = info->bytes;
	cell->name = info->name;

	cell->bit_offset = info->bit_offset;
	cell->nbits = info->nbits;

	if (cell->nbits)
		cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset,
					   BITS_PER_BYTE);

	if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
		dev_err(&nvmem->dev,
			"cell %s unaligned to nvmem stride %d\n",
			cell->name, nvmem->stride);
		return -EINVAL;
	}

	return 0;
}

/**
 * nvmem_add_cells() - Add cell information to an nvmem device
 *
 * @nvmem: nvmem device to add cells to.
 * @info: nvmem cell info to add to the device
 * @ncells: number of cells in info
 *
 * Return: 0 or negative error code on failure.
 */
static int nvmem_add_cells(struct nvmem_device *nvmem,
		    const struct nvmem_cell_info *info,
		    int ncells)
{
	struct nvmem_cell **cells;
	int i, rval;

	cells = kcalloc(ncells, sizeof(*cells), GFP_KERNEL);
	if (!cells)
		return -ENOMEM;

	for (i = 0; i < ncells; i++) {
		cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL);
		if (!cells[i]) {
			rval = -ENOMEM;
			goto err;
		}

		rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]);
		if (rval) {
			kfree(cells[i]);
			goto err;
		}

		nvmem_cell_add(cells[i]);
	}

	/* remove tmp array */
	kfree(cells);

	return 0;
err:
	while (i--)
		nvmem_cell_drop(cells[i]);

	kfree(cells);

	return rval;
}

/**
 * nvmem_register_notifier() - Register a notifier block for nvmem events.
 *
 * @nb: notifier block to be called on nvmem events.
 *
 * Return: 0 on success, negative error number on failure.
 */
int nvmem_register_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_register(&nvmem_notifier, nb);
}
EXPORT_SYMBOL_GPL(nvmem_register_notifier);

/**
 * nvmem_unregister_notifier() - Unregister a notifier block for nvmem events.
 *
 * @nb: notifier block to be unregistered.
 *
 * Return: 0 on success, negative error number on failure.
 */
int nvmem_unregister_notifier(struct notifier_block *nb)
{
	return blocking_notifier_chain_unregister(&nvmem_notifier, nb);
}
EXPORT_SYMBOL_GPL(nvmem_unregister_notifier);

static int nvmem_add_cells_from_table(struct nvmem_device *nvmem)
{
	const struct nvmem_cell_info *info;
	struct nvmem_cell_table *table;
	struct nvmem_cell *cell;
	int rval = 0, i;

	mutex_lock(&nvmem_cell_mutex);
	list_for_each_entry(table, &nvmem_cell_tables, node) {
		if (strcmp(nvmem_dev_name(nvmem), table->nvmem_name) == 0) {
			for (i = 0; i < table->ncells; i++) {
				info = &table->cells[i];

				cell = kzalloc(sizeof(*cell), GFP_KERNEL);
				if (!cell) {
					rval = -ENOMEM;
					goto out;
				}

				rval = nvmem_cell_info_to_nvmem_cell(nvmem,
								     info,
								     cell);
				if (rval) {
					kfree(cell);
					goto out;
				}

				nvmem_cell_add(cell);
			}
		}
	}

out:
	mutex_unlock(&nvmem_cell_mutex);
	return rval;
}

static struct nvmem_cell *
nvmem_find_cell_by_name(struct nvmem_device *nvmem, const char *cell_id)
{
	struct nvmem_cell *iter, *cell = NULL;

	mutex_lock(&nvmem_mutex);
	list_for_each_entry(iter, &nvmem->cells, node) {
		if (strcmp(cell_id, iter->name) == 0) {
			cell = iter;
			break;
		}
	}
	mutex_unlock(&nvmem_mutex);

	return cell;
}

static int nvmem_add_cells_from_of(struct nvmem_device *nvmem)
{
	struct device_node *parent, *child;
	struct device *dev = &nvmem->dev;
	struct nvmem_cell *cell;
	const __be32 *addr;
	int len;

	parent = dev->of_node;

	for_each_child_of_node(parent, child) {
		addr = of_get_property(child, "reg", &len);
		if (!addr || (len < 2 * sizeof(u32))) {
			dev_err(dev, "nvmem: invalid reg on %pOF\n", child);
			return -EINVAL;
		}

		cell = kzalloc(sizeof(*cell), GFP_KERNEL);
		if (!cell)
			return -ENOMEM;

		cell->nvmem = nvmem;
		cell->np = of_node_get(child);
		cell->offset = be32_to_cpup(addr++);
		cell->bytes = be32_to_cpup(addr);
		cell->name = kasprintf(GFP_KERNEL, "%pOFn", child);

		addr = of_get_property(child, "bits", &len);
		if (addr && len == (2 * sizeof(u32))) {
			cell->bit_offset = be32_to_cpup(addr++);
			cell->nbits = be32_to_cpup(addr);
		}

		if (cell->nbits)
			cell->bytes = DIV_ROUND_UP(
					cell->nbits + cell->bit_offset,
					BITS_PER_BYTE);

		if (!IS_ALIGNED(cell->offset, nvmem->stride)) {
			dev_err(dev, "cell %s unaligned to nvmem stride %d\n",
				cell->name, nvmem->stride);
			/* Cells already added will be freed later. */
			kfree(cell->name);
			kfree(cell);
			return -EINVAL;
		}

		nvmem_cell_add(cell);
	}

	return 0;
}

/**
 * nvmem_register() - Register a nvmem device for given nvmem_config.
 * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 *
 * @config: nvmem device configuration with which nvmem device is created.
 *
 * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 * on success.
 */

struct nvmem_device *nvmem_register(const struct nvmem_config *config)
{
	struct nvmem_device *nvmem;
	int rval;

	if (!config->dev)
		return ERR_PTR(-EINVAL);

	nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL);
	if (!nvmem)
		return ERR_PTR(-ENOMEM);

	rval  = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL);
	if (rval < 0) {
		kfree(nvmem);
		return ERR_PTR(rval);
	}

	kref_init(&nvmem->refcnt);
	INIT_LIST_HEAD(&nvmem->cells);

	nvmem->id = rval;
	nvmem->owner = config->owner;
	if (!nvmem->owner && config->dev->driver)
		nvmem->owner = config->dev->driver->owner;
	nvmem->stride = config->stride ?: 1;
	nvmem->word_size = config->word_size ?: 1;
	nvmem->size = config->size;
	nvmem->dev.type = &nvmem_provider_type;
	nvmem->dev.bus = &nvmem_bus_type;
	nvmem->dev.parent = config->dev;
	nvmem->priv = config->priv;
	nvmem->type = config->type;
	nvmem->reg_read = config->reg_read;
	nvmem->reg_write = config->reg_write;
	if (!config->no_of_node)
		nvmem->dev.of_node = config->dev->of_node;

	if (config->id == -1 && config->name) {
		dev_set_name(&nvmem->dev, "%s", config->name);
	} else {
		dev_set_name(&nvmem->dev, "%s%d",
			     config->name ? : "nvmem",
			     config->name ? config->id : nvmem->id);
	}

	nvmem->read_only = device_property_present(config->dev, "read-only") ||
			   config->read_only || !nvmem->reg_write;

	nvmem->dev.groups = nvmem_sysfs_get_groups(nvmem, config);

	device_initialize(&nvmem->dev);

	dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);

	rval = device_add(&nvmem->dev);
	if (rval)
		goto err_put_device;

	if (config->compat) {
		rval = nvmem_sysfs_setup_compat(nvmem, config);
		if (rval)
			goto err_device_del;
	}

	if (config->cells) {
		rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
		if (rval)
			goto err_teardown_compat;
	}

	rval = nvmem_add_cells_from_table(nvmem);
	if (rval)
		goto err_remove_cells;

	rval = nvmem_add_cells_from_of(nvmem);
	if (rval)
		goto err_remove_cells;

	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);

	return nvmem;

err_remove_cells:
	nvmem_device_remove_all_cells(nvmem);
err_teardown_compat:
	if (config->compat)
		nvmem_sysfs_remove_compat(nvmem, config);
err_device_del:
	device_del(&nvmem->dev);
err_put_device:
	put_device(&nvmem->dev);

	return ERR_PTR(rval);
}
EXPORT_SYMBOL_GPL(nvmem_register);

static void nvmem_device_release(struct kref *kref)
{
	struct nvmem_device *nvmem;

	nvmem = container_of(kref, struct nvmem_device, refcnt);

	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_REMOVE, nvmem);

	if (nvmem->flags & FLAG_COMPAT)
		device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);

	nvmem_device_remove_all_cells(nvmem);
	device_del(&nvmem->dev);
	put_device(&nvmem->dev);
}

/**
 * nvmem_unregister() - Unregister previously registered nvmem device
 *
 * @nvmem: Pointer to previously registered nvmem device.
 */
void nvmem_unregister(struct nvmem_device *nvmem)
{
	kref_put(&nvmem->refcnt, nvmem_device_release);
}
EXPORT_SYMBOL_GPL(nvmem_unregister);

static void devm_nvmem_release(struct device *dev, void *res)
{
	nvmem_unregister(*(struct nvmem_device **)res);
}

/**
 * devm_nvmem_register() - Register a managed nvmem device for given
 * nvmem_config.
 * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem
 *
 * @dev: Device that uses the nvmem device.
 * @config: nvmem device configuration with which nvmem device is created.
 *
 * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device
 * on success.
 */
struct nvmem_device *devm_nvmem_register(struct device *dev,
					 const struct nvmem_config *config)
{
	struct nvmem_device **ptr, *nvmem;

	ptr = devres_alloc(devm_nvmem_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return ERR_PTR(-ENOMEM);

	nvmem = nvmem_register(config);

	if (!IS_ERR(nvmem)) {
		*ptr = nvmem;
		devres_add(dev, ptr);
	} else {
		devres_free(ptr);
	}

	return nvmem;
}
EXPORT_SYMBOL_GPL(devm_nvmem_register);

static int devm_nvmem_match(struct device *dev, void *res, void *data)
{
	struct nvmem_device **r = res;

	return *r == data;
}

/**
 * devm_nvmem_unregister() - Unregister previously registered managed nvmem
 * device.
 *
 * @dev: Device that uses the nvmem device.
 * @nvmem: Pointer to previously registered nvmem device.
 *
 * Return: Will be an negative on error or a zero on success.
 */
int devm_nvmem_unregister(struct device *dev, struct nvmem_device *nvmem)
{
	return devres_release(dev, devm_nvmem_release, devm_nvmem_match, nvmem);
}
EXPORT_SYMBOL(devm_nvmem_unregister);

static struct nvmem_device *__nvmem_device_get(struct device_node *np,
					       const char *nvmem_name)
{
	struct nvmem_device *nvmem = NULL;

	mutex_lock(&nvmem_mutex);
	nvmem = np ? of_nvmem_find(np) : nvmem_find(nvmem_name);
	mutex_unlock(&nvmem_mutex);
	if (!nvmem)
		return ERR_PTR(-EPROBE_DEFER);

	if (!try_module_get(nvmem->owner)) {
		dev_err(&nvmem->dev,
			"could not increase module refcount for cell %s\n",
			nvmem_dev_name(nvmem));

		put_device(&nvmem->dev);
		return ERR_PTR(-EINVAL);
	}

	kref_get(&nvmem->refcnt);

	return nvmem;
}

static void __nvmem_device_put(struct nvmem_device *nvmem)
{
	put_device(&nvmem->dev);
	module_put(nvmem->owner);
	kref_put(&nvmem->refcnt, nvmem_device_release);
}

#if IS_ENABLED(CONFIG_OF)
/**
 * of_nvmem_device_get() - Get nvmem device from a given id
 *
 * @np: Device tree node that uses the nvmem device.
 * @id: nvmem name from nvmem-names property.
 *
 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 * on success.
 */
struct nvmem_device *of_nvmem_device_get(struct device_node *np, const char *id)
{

	struct device_node *nvmem_np;
	int index = 0;

	if (id)
		index = of_property_match_string(np, "nvmem-names", id);

	nvmem_np = of_parse_phandle(np, "nvmem", index);
	if (!nvmem_np)
		return ERR_PTR(-ENOENT);

	return __nvmem_device_get(nvmem_np, NULL);
}
EXPORT_SYMBOL_GPL(of_nvmem_device_get);
#endif

/**
 * nvmem_device_get() - Get nvmem device from a given id
 *
 * @dev: Device that uses the nvmem device.
 * @dev_name: name of the requested nvmem device.
 *
 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_device
 * on success.
 */
struct nvmem_device *nvmem_device_get(struct device *dev, const char *dev_name)
{
	if (dev->of_node) { /* try dt first */
		struct nvmem_device *nvmem;

		nvmem = of_nvmem_device_get(dev->of_node, dev_name);

		if (!IS_ERR(nvmem) || PTR_ERR(nvmem) == -EPROBE_DEFER)
			return nvmem;

	}

	return __nvmem_device_get(NULL, dev_name);
}
EXPORT_SYMBOL_GPL(nvmem_device_get);

static int devm_nvmem_device_match(struct device *dev, void *res, void *data)
{
	struct nvmem_device **nvmem = res;

	if (WARN_ON(!nvmem || !*nvmem))
		return 0;

	return *nvmem == data;
}

static void devm_nvmem_device_release(struct device *dev, void *res)
{
	nvmem_device_put(*(struct nvmem_device **)res);
}

/**
 * devm_nvmem_device_put() - put alredy got nvmem device
 *
 * @dev: Device that uses the nvmem device.
 * @nvmem: pointer to nvmem device allocated by devm_nvmem_cell_get(),
 * that needs to be released.
 */
void devm_nvmem_device_put(struct device *dev, struct nvmem_device *nvmem)
{
	int ret;

	ret = devres_release(dev, devm_nvmem_device_release,
			     devm_nvmem_device_match, nvmem);

	WARN_ON(ret);
}
EXPORT_SYMBOL_GPL(devm_nvmem_device_put);

/**
 * nvmem_device_put() - put alredy got nvmem device
 *
 * @nvmem: pointer to nvmem device that needs to be released.
 */
void nvmem_device_put(struct nvmem_device *nvmem)
{
	__nvmem_device_put(nvmem);
}
EXPORT_SYMBOL_GPL(nvmem_device_put);

/**
 * devm_nvmem_device_get() - Get nvmem cell of device form a given id
 *
 * @dev: Device that requests the nvmem device.
 * @id: name id for the requested nvmem device.
 *
 * Return: ERR_PTR() on error or a valid pointer to a struct nvmem_cell
 * on success.  The nvmem_cell will be freed by the automatically once the
 * device is freed.
 */
struct nvmem_device *devm_nvmem_device_get(struct device *dev, const char *id)
{
	struct nvmem_device **ptr, *nvmem;

	ptr = devres_alloc(devm_nvmem_device_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return ERR_PTR(-ENOMEM);

	nvmem = nvmem_device_get(dev, id);
	if (!IS_ERR(nvmem)) {
		*ptr = nvmem;
		devres_add(dev, ptr);
	} else {
		devres_free(ptr);
	}

	return nvmem;
}
EXPORT_SYMBOL_GPL(devm_nvmem_device_get);

static struct nvmem_cell *
nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
{
	struct nvmem_cell *cell = ERR_PTR(-ENOENT);
	struct nvmem_cell_lookup *lookup;
	struct nvmem_device *nvmem;
	const char *dev_id;

	if (!dev)
		return ERR_PTR(-EINVAL);

	dev_id = dev_name(dev);

	mutex_lock(&nvmem_lookup_mutex);

	list_for_each_entry(lookup, &nvmem_lookup_list, node) {
		if ((strcmp(lookup->dev_id, dev_id) == 0) &&
		    (strcmp(lookup->con_id, con_id) == 0)) {
			/* This is the right entry. */
			nvmem = __nvmem_device_get(NULL, lookup->nvmem_name);
			if (IS_ERR(nvmem)) {
				/* Provider may not be registered yet. */
				cell = ERR_CAST(nvmem);
				break;
			}

			cell = nvmem_find_cell_by_name(nvmem,
						       lookup->cell_name);
			if (!cell) {
				__nvmem_device_put(nvmem);
				cell = ERR_PTR(-ENOENT);
			}
			break;
		}
	}

	mutex_unlock(&nvmem_lookup_mutex);
	return cell;
}

#if IS_ENABLED(CONFIG_OF)
static struct nvmem_cell *
nvmem_find_cell_by_node(struct nvmem_device *nvmem, struct device_node *np)
{
	struct nvmem_cell *iter, *cell = NULL;

	mutex_lock(&nvmem_mutex);
	list_for_each_entry(iter, &nvmem->cells, node) {
		if (np == iter->np) {
			cell = iter;
			break;
		}
	}
	mutex_unlock(&nvmem_mutex);

	return cell;
}

/**
 * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
 *
 * @np: Device tree node that uses the nvmem cell.
 * @id: nvmem cell name from nvmem-cell-names property, or NULL
 *      for the cell at index 0 (the lone cell with no accompanying
 *      nvmem-cell-names property).
 *
 * Return: Will be an ERR_PTR() on error or a valid pointer
 * to a struct nvmem_cell.  The nvmem_cell will be freed by the
 * nvmem_cell_put().
 */
struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
{
	struct device_node *cell_np, *nvmem_np;
	struct nvmem_device *nvmem;
	struct nvmem_cell *cell;
	int index = 0;

	/* if cell name exists, find index to the name */
	if (id)
		index = of_property_match_string(np, "nvmem-cell-names", id);

	cell_np = of_parse_phandle(np, "nvmem-cells", index);
	if (!cell_np)
		return ERR_PTR(-ENOENT);

	nvmem_np = of_get_next_parent(cell_np);
	if (!nvmem_np)
		return ERR_PTR(-EINVAL);

	nvmem = __nvmem_device_get(nvmem_np, NULL);
	of_node_put(nvmem_np);
	if (IS_ERR(nvmem))
		return ERR_CAST(nvmem);

	cell = nvmem_find_cell_by_node(nvmem, cell_np);
	if (!cell) {
		__nvmem_device_put(nvmem);
		return ERR_PTR(-ENOENT);
	}

	return cell;
}
EXPORT_SYMBOL_GPL(of_nvmem_cell_get);
#endif

/**
 * nvmem_cell_get() - Get nvmem cell of device form a given cell name
 *
 * @dev: Device that requests the nvmem cell.
 * @id: nvmem cell name to get (this corresponds with the name from the
 *      nvmem-cell-names property for DT systems and with the con_id from
 *      the lookup entry for non-DT systems).
 *
 * Return: Will be an ERR_PTR() on error or a valid pointer
 * to a struct nvmem_cell.  The nvmem_cell will be freed by the
 * nvmem_cell_put().
 */
struct nvmem_cell *nvmem_cell_get(struct device *dev, const char *id)
{
	struct nvmem_cell *cell;

	if (dev->of_node) { /* try dt first */
		cell = of_nvmem_cell_get(dev->of_node, id);
		if (!IS_ERR(cell) || PTR_ERR(cell) == -EPROBE_DEFER)
			return cell;
	}

	/* NULL cell id only allowed for device tree; invalid otherwise */
	if (!id)
		return ERR_PTR(-EINVAL);

	return nvmem_cell_get_from_lookup(dev, id);
}
EXPORT_SYMBOL_GPL(nvmem_cell_get);

static void devm_nvmem_cell_release(struct device *dev, void *res)
{
	nvmem_cell_put(*(struct nvmem_cell **)res);
}

/**
 * devm_nvmem_cell_get() - Get nvmem cell of device form a given id
 *
 * @dev: Device that requests the nvmem cell.
 * @id: nvmem cell name id to get.
 *
 * Return: Will be an ERR_PTR() on error or a valid pointer
 * to a struct nvmem_cell.  The nvmem_cell will be freed by the
 * automatically once the device is freed.
 */
struct nvmem_cell *devm_nvmem_cell_get(struct device *dev, const char *id)
{
	struct nvmem_cell **ptr, *cell;

	ptr = devres_alloc(devm_nvmem_cell_release, sizeof(*ptr), GFP_KERNEL);
	if (!ptr)
		return ERR_PTR(-ENOMEM);

	cell = nvmem_cell_get(dev, id);
	if (!IS_ERR(cell)) {
		*ptr = cell;
		devres_add(dev, ptr);
	} else {
		devres_free(ptr);
	}

	return cell;
}
EXPORT_SYMBOL_GPL(devm_nvmem_cell_get);

static int devm_nvmem_cell_match(struct device *dev, void *res, void *data)
{
	struct nvmem_cell **c = res;

	if (WARN_ON(!c || !*c))
		return 0;

	return *c == data;
}

/**
 * devm_nvmem_cell_put() - Release previously allocated nvmem cell
 * from devm_nvmem_cell_get.
 *
 * @dev: Device that requests the nvmem cell.
 * @cell: Previously allocated nvmem cell by devm_nvmem_cell_get().
 */
void devm_nvmem_cell_put(struct device *dev, struct nvmem_cell *cell)
{
	int ret;

	ret = devres_release(dev, devm_nvmem_cell_release,
				devm_nvmem_cell_match, cell);

	WARN_ON(ret);
}
EXPORT_SYMBOL(devm_nvmem_cell_put);

/**
 * nvmem_cell_put() - Release previously allocated nvmem cell.
 *
 * @cell: Previously allocated nvmem cell by nvmem_cell_get().
 */
void nvmem_cell_put(struct nvmem_cell *cell)
{
	struct nvmem_device *nvmem = cell->nvmem;

	__nvmem_device_put(nvmem);
}
EXPORT_SYMBOL_GPL(nvmem_cell_put);

static void nvmem_shift_read_buffer_in_place(struct nvmem_cell *cell, void *buf)
{
	u8 *p, *b;
	int i, extra, bit_offset = cell->bit_offset;

	p = b = buf;
	if (bit_offset) {
		/* First shift */
		*b++ >>= bit_offset;

		/* setup rest of the bytes if any */
		for (i = 1; i < cell->bytes; i++) {
			/* Get bits from next byte and shift them towards msb */
			*p |= *b << (BITS_PER_BYTE - bit_offset);

			p = b;
			*b++ >>= bit_offset;
		}
	} else {
		/* point to the msb */
		p += cell->bytes - 1;
	}

	/* result fits in less bytes */
	extra = cell->bytes - DIV_ROUND_UP(cell->nbits, BITS_PER_BYTE);
	while (--extra >= 0)
		*p-- = 0;

	/* clear msb bits if any leftover in the last byte */
	*p &= GENMASK((cell->nbits%BITS_PER_BYTE) - 1, 0);
}

static int __nvmem_cell_read(struct nvmem_device *nvmem,
		      struct nvmem_cell *cell,
		      void *buf, size_t *len)
{
	int rc;

	rc = nvmem_reg_read(nvmem, cell->offset, buf, cell->bytes);

	if (rc)
		return rc;

	/* shift bits in-place */
	if (cell->bit_offset || cell->nbits)
		nvmem_shift_read_buffer_in_place(cell, buf);

	if (len)
		*len = cell->bytes;

	return 0;
}

/**
 * nvmem_cell_read() - Read a given nvmem cell
 *
 * @cell: nvmem cell to be read.
 * @len: pointer to length of cell which will be populated on successful read;
 *	 can be NULL.
 *
 * Return: ERR_PTR() on error or a valid pointer to a buffer on success. The
 * buffer should be freed by the consumer with a kfree().
 */
void *nvmem_cell_read(struct nvmem_cell *cell, size_t *len)
{
	struct nvmem_device *nvmem = cell->nvmem;
	u8 *buf;
	int rc;

	if (!nvmem)
		return ERR_PTR(-EINVAL);

	buf = kzalloc(cell->bytes, GFP_KERNEL);
	if (!buf)
		return ERR_PTR(-ENOMEM);

	rc = __nvmem_cell_read(nvmem, cell, buf, len);
	if (rc) {
		kfree(buf);
		return ERR_PTR(rc);
	}

	return buf;
}
EXPORT_SYMBOL_GPL(nvmem_cell_read);

static void *nvmem_cell_prepare_write_buffer(struct nvmem_cell *cell,
					     u8 *_buf, int len)
{
	struct nvmem_device *nvmem = cell->nvmem;
	int i, rc, nbits, bit_offset = cell->bit_offset;
	u8 v, *p, *buf, *b, pbyte, pbits;

	nbits = cell->nbits;
	buf = kzalloc(cell->bytes, GFP_KERNEL);
	if (!buf)
		return ERR_PTR(-ENOMEM);

	memcpy(buf, _buf, len);
	p = b = buf;

	if (bit_offset) {
		pbyte = *b;
		*b <<= bit_offset;

		/* setup the first byte with lsb bits from nvmem */
		rc = nvmem_reg_read(nvmem, cell->offset, &v, 1);
		if (rc)
			goto err;
		*b++ |= GENMASK(bit_offset - 1, 0) & v;

		/* setup rest of the byte if any */
		for (i = 1; i < cell->bytes; i++) {
			/* Get last byte bits and shift them towards lsb */
			pbits = pbyte >> (BITS_PER_BYTE - 1 - bit_offset);
			pbyte = *b;
			p = b;
			*b <<= bit_offset;
			*b++ |= pbits;
		}
	}

	/* if it's not end on byte boundary */
	if ((nbits + bit_offset) % BITS_PER_BYTE) {
		/* setup the last byte with msb bits from nvmem */
		rc = nvmem_reg_read(nvmem,
				    cell->offset + cell->bytes - 1, &v, 1);
		if (rc)
			goto err;
		*p |= GENMASK(7, (nbits + bit_offset) % BITS_PER_BYTE) & v;

	}

	return buf;
err:
	kfree(buf);
	return ERR_PTR(rc);
}

/**
 * nvmem_cell_write() - Write to a given nvmem cell
 *
 * @cell: nvmem cell to be written.
 * @buf: Buffer to be written.
 * @len: length of buffer to be written to nvmem cell.
 *
 * Return: length of bytes written or negative on failure.
 */
int nvmem_cell_write(struct nvmem_cell *cell, void *buf, size_t len)
{
	struct nvmem_device *nvmem = cell->nvmem;
	int rc;

	if (!nvmem || nvmem->read_only ||
	    (cell->bit_offset == 0 && len != cell->bytes))
		return -EINVAL;

	if (cell->bit_offset || cell->nbits) {
		buf = nvmem_cell_prepare_write_buffer(cell, buf, len);
		if (IS_ERR(buf))
			return PTR_ERR(buf);
	}

	rc = nvmem_reg_write(nvmem, cell->offset, buf, cell->bytes);

	/* free the tmp buffer */
	if (cell->bit_offset || cell->nbits)
		kfree(buf);

	if (rc)
		return rc;

	return len;
}
EXPORT_SYMBOL_GPL(nvmem_cell_write);

/**
 * nvmem_cell_read_u16() - Read a cell value as an u16
 *
 * @dev: Device that requests the nvmem cell.
 * @cell_id: Name of nvmem cell to read.
 * @val: pointer to output value.
 *
 * Return: 0 on success or negative errno.
 */
int nvmem_cell_read_u16(struct device *dev, const char *cell_id, u16 *val)
{
	struct nvmem_cell *cell;
	void *buf;
	size_t len;

	cell = nvmem_cell_get(dev, cell_id);
	if (IS_ERR(cell))
		return PTR_ERR(cell);

	buf = nvmem_cell_read(cell, &len);
	if (IS_ERR(buf)) {
		nvmem_cell_put(cell);
		return PTR_ERR(buf);
	}
	if (len != sizeof(*val)) {
		kfree(buf);
		nvmem_cell_put(cell);
		return -EINVAL;
	}
	memcpy(val, buf, sizeof(*val));
	kfree(buf);
	nvmem_cell_put(cell);

	return 0;
}
EXPORT_SYMBOL_GPL(nvmem_cell_read_u16);

/**
 * nvmem_cell_read_u32() - Read a cell value as an u32
 *
 * @dev: Device that requests the nvmem cell.
 * @cell_id: Name of nvmem cell to read.
 * @val: pointer to output value.
 *
 * Return: 0 on success or negative errno.
 */
int nvmem_cell_read_u32(struct device *dev, const char *cell_id, u32 *val)
{
	struct nvmem_cell *cell;
	void *buf;
	size_t len;

	cell = nvmem_cell_get(dev, cell_id);
	if (IS_ERR(cell))
		return PTR_ERR(cell);

	buf = nvmem_cell_read(cell, &len);
	if (IS_ERR(buf)) {
		nvmem_cell_put(cell);
		return PTR_ERR(buf);
	}
	if (len != sizeof(*val)) {
		kfree(buf);
		nvmem_cell_put(cell);
		return -EINVAL;
	}
	memcpy(val, buf, sizeof(*val));

	kfree(buf);
	nvmem_cell_put(cell);
	return 0;
}
EXPORT_SYMBOL_GPL(nvmem_cell_read_u32);

/**
 * nvmem_device_cell_read() - Read a given nvmem device and cell
 *
 * @nvmem: nvmem device to read from.
 * @info: nvmem cell info to be read.
 * @buf: buffer pointer which will be populated on successful read.
 *
 * Return: length of successful bytes read on success and negative
 * error code on error.
 */
ssize_t nvmem_device_cell_read(struct nvmem_device *nvmem,
			   struct nvmem_cell_info *info, void *buf)
{
	struct nvmem_cell cell;
	int rc;
	ssize_t len;

	if (!nvmem)
		return -EINVAL;

	rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
	if (rc)
		return rc;

	rc = __nvmem_cell_read(nvmem, &cell, buf, &len);
	if (rc)
		return rc;

	return len;
}
EXPORT_SYMBOL_GPL(nvmem_device_cell_read);

/**
 * nvmem_device_cell_write() - Write cell to a given nvmem device
 *
 * @nvmem: nvmem device to be written to.
 * @info: nvmem cell info to be written.
 * @buf: buffer to be written to cell.
 *
 * Return: length of bytes written or negative error code on failure.
 */
int nvmem_device_cell_write(struct nvmem_device *nvmem,
			    struct nvmem_cell_info *info, void *buf)
{
	struct nvmem_cell cell;
	int rc;

	if (!nvmem)
		return -EINVAL;

	rc = nvmem_cell_info_to_nvmem_cell(nvmem, info, &cell);
	if (rc)
		return rc;

	return nvmem_cell_write(&cell, buf, cell.bytes);
}
EXPORT_SYMBOL_GPL(nvmem_device_cell_write);

/**
 * nvmem_device_read() - Read from a given nvmem device
 *
 * @nvmem: nvmem device to read from.
 * @offset: offset in nvmem device.
 * @bytes: number of bytes to read.
 * @buf: buffer pointer which will be populated on successful read.
 *
 * Return: length of successful bytes read on success and negative
 * error code on error.
 */
int nvmem_device_read(struct nvmem_device *nvmem,
		      unsigned int offset,
		      size_t bytes, void *buf)
{
	int rc;

	if (!nvmem)
		return -EINVAL;

	rc = nvmem_reg_read(nvmem, offset, buf, bytes);

	if (rc)
		return rc;

	return bytes;
}
EXPORT_SYMBOL_GPL(nvmem_device_read);

/**
 * nvmem_device_write() - Write cell to a given nvmem device
 *
 * @nvmem: nvmem device to be written to.
 * @offset: offset in nvmem device.
 * @bytes: number of bytes to write.
 * @buf: buffer to be written.
 *
 * Return: length of bytes written or negative error code on failure.
 */
int nvmem_device_write(struct nvmem_device *nvmem,
		       unsigned int offset,
		       size_t bytes, void *buf)
{
	int rc;

	if (!nvmem)
		return -EINVAL;

	rc = nvmem_reg_write(nvmem, offset, buf, bytes);

	if (rc)
		return rc;


	return bytes;
}
EXPORT_SYMBOL_GPL(nvmem_device_write);

/**
 * nvmem_add_cell_table() - register a table of cell info entries
 *
 * @table: table of cell info entries
 */
void nvmem_add_cell_table(struct nvmem_cell_table *table)
{
	mutex_lock(&nvmem_cell_mutex);
	list_add_tail(&table->node, &nvmem_cell_tables);
	mutex_unlock(&nvmem_cell_mutex);
}
EXPORT_SYMBOL_GPL(nvmem_add_cell_table);

/**
 * nvmem_del_cell_table() - remove a previously registered cell info table
 *
 * @table: table of cell info entries
 */
void nvmem_del_cell_table(struct nvmem_cell_table *table)
{
	mutex_lock(&nvmem_cell_mutex);
	list_del(&table->node);
	mutex_unlock(&nvmem_cell_mutex);
}
EXPORT_SYMBOL_GPL(nvmem_del_cell_table);

/**
 * nvmem_add_cell_lookups() - register a list of cell lookup entries
 *
 * @entries: array of cell lookup entries
 * @nentries: number of cell lookup entries in the array
 */
void nvmem_add_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
{
	int i;

	mutex_lock(&nvmem_lookup_mutex);
	for (i = 0; i < nentries; i++)
		list_add_tail(&entries[i].node, &nvmem_lookup_list);
	mutex_unlock(&nvmem_lookup_mutex);
}
EXPORT_SYMBOL_GPL(nvmem_add_cell_lookups);

/**
 * nvmem_del_cell_lookups() - remove a list of previously added cell lookup
 *                            entries
 *
 * @entries: array of cell lookup entries
 * @nentries: number of cell lookup entries in the array
 */
void nvmem_del_cell_lookups(struct nvmem_cell_lookup *entries, size_t nentries)
{
	int i;

	mutex_lock(&nvmem_lookup_mutex);
	for (i = 0; i < nentries; i++)
		list_del(&entries[i].node);
	mutex_unlock(&nvmem_lookup_mutex);
}
EXPORT_SYMBOL_GPL(nvmem_del_cell_lookups);

/**
 * nvmem_dev_name() - Get the name of a given nvmem device.
 *
 * @nvmem: nvmem device.
 *
 * Return: name of the nvmem device.
 */
const char *nvmem_dev_name(struct nvmem_device *nvmem)
{
	return dev_name(&nvmem->dev);
}
EXPORT_SYMBOL_GPL(nvmem_dev_name);

static int __init nvmem_init(void)
{
	return bus_register(&nvmem_bus_type);
}

static void __exit nvmem_exit(void)
{
	bus_unregister(&nvmem_bus_type);
}

subsys_initcall(nvmem_init);
module_exit(nvmem_exit);

MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org");
MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com");
MODULE_DESCRIPTION("nvmem Driver Core");
MODULE_LICENSE("GPL v2");