summaryrefslogtreecommitdiff
path: root/drivers/hte/hte.c
blob: 23a6eeb8c506c29d74bc720f35b3eb273a3f6c26 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2021-2022 NVIDIA Corporation
 *
 * Author: Dipen Patel <dipenp@nvidia.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <linux/hte.h>
#include <linux/delay.h>
#include <linux/debugfs.h>
#include <linux/device.h>

/* Global list of the HTE devices */
static DEFINE_SPINLOCK(hte_lock);
static LIST_HEAD(hte_devices);

enum {
	HTE_TS_REGISTERED,
	HTE_TS_REQ,
	HTE_TS_DISABLE,
	HTE_TS_QUEUE_WK,
};

/**
 * struct hte_ts_info - Information related to requested timestamp.
 *
 * @xlated_id: Timestamp ID as understood between HTE subsys and HTE provider,
 * See xlate callback API.
 * @flags: Flags holding state information.
 * @hte_cb_flags: Callback related flags.
 * @seq: Timestamp sequence counter.
 * @line_name: HTE allocated line name.
 * @free_attr_name: If set, free the attr name.
 * @cb: A nonsleeping callback function provided by clients.
 * @tcb: A secondary sleeping callback function provided by clients.
 * @dropped_ts: Dropped timestamps.
 * @slock: Spin lock to synchronize between disable/enable,
 * request/release APIs.
 * @cb_work: callback workqueue, used when tcb is specified.
 * @req_mlock: Lock during timestamp request/release APIs.
 * @ts_dbg_root: Root for the debug fs.
 * @gdev: HTE abstract device that this timestamp information belongs to.
 * @cl_data: Client specific data.
 */
struct hte_ts_info {
	u32 xlated_id;
	unsigned long flags;
	unsigned long hte_cb_flags;
	u64 seq;
	char *line_name;
	bool free_attr_name;
	hte_ts_cb_t cb;
	hte_ts_sec_cb_t tcb;
	atomic_t dropped_ts;
	spinlock_t slock;
	struct work_struct cb_work;
	struct mutex req_mlock;
	struct dentry *ts_dbg_root;
	struct hte_device *gdev;
	void *cl_data;
};

/**
 * struct hte_device - HTE abstract device
 * @nlines: Number of entities this device supports.
 * @ts_req: Total number of entities requested.
 * @sdev: Device used at various debug prints.
 * @dbg_root: Root directory for debug fs.
 * @list: List node to store hte_device for each provider.
 * @chip: HTE chip providing this HTE device.
 * @owner: helps prevent removal of modules when in use.
 * @ei: Timestamp information.
 */
struct hte_device {
	u32 nlines;
	atomic_t ts_req;
	struct device *sdev;
	struct dentry *dbg_root;
	struct list_head list;
	struct hte_chip *chip;
	struct module *owner;
	struct hte_ts_info ei[] __counted_by(nlines);
};

#ifdef CONFIG_DEBUG_FS

static struct dentry *hte_root;

static int __init hte_subsys_dbgfs_init(void)
{
	/* creates /sys/kernel/debug/hte/ */
	hte_root = debugfs_create_dir("hte", NULL);

	return 0;
}
subsys_initcall(hte_subsys_dbgfs_init);

static void hte_chip_dbgfs_init(struct hte_device *gdev)
{
	const struct hte_chip *chip = gdev->chip;
	const char *name = chip->name ? chip->name : dev_name(chip->dev);

	gdev->dbg_root = debugfs_create_dir(name, hte_root);

	debugfs_create_atomic_t("ts_requested", 0444, gdev->dbg_root,
				&gdev->ts_req);
	debugfs_create_u32("total_ts", 0444, gdev->dbg_root,
			   &gdev->nlines);
}

static void hte_ts_dbgfs_init(const char *name, struct hte_ts_info *ei)
{
	if (!ei->gdev->dbg_root || !name)
		return;

	ei->ts_dbg_root = debugfs_create_dir(name, ei->gdev->dbg_root);

	debugfs_create_atomic_t("dropped_timestamps", 0444, ei->ts_dbg_root,
				&ei->dropped_ts);
}

#else

static void hte_chip_dbgfs_init(struct hte_device *gdev)
{
}

static void hte_ts_dbgfs_init(const char *name, struct hte_ts_info *ei)
{
}

#endif

/**
 * hte_ts_put() - Release and disable timestamp for the given desc.
 *
 * @desc: timestamp descriptor.
 *
 * Context: debugfs_remove_recursive() function call may use sleeping locks,
 *	    not suitable from atomic context.
 * Returns: 0 on success or a negative error code on failure.
 */
int hte_ts_put(struct hte_ts_desc *desc)
{
	int ret = 0;
	unsigned long flag;
	struct hte_device *gdev;
	struct hte_ts_info *ei;

	if (!desc)
		return -EINVAL;

	ei = desc->hte_data;

	if (!ei || !ei->gdev)
		return -EINVAL;

	gdev = ei->gdev;

	mutex_lock(&ei->req_mlock);

	if (unlikely(!test_bit(HTE_TS_REQ, &ei->flags) &&
	    !test_bit(HTE_TS_REGISTERED, &ei->flags))) {
		dev_info(gdev->sdev, "id:%d is not requested\n",
			 desc->attr.line_id);
		ret = -EINVAL;
		goto unlock;
	}

	if (unlikely(!test_bit(HTE_TS_REQ, &ei->flags) &&
	    test_bit(HTE_TS_REGISTERED, &ei->flags))) {
		dev_info(gdev->sdev, "id:%d is registered but not requested\n",
			 desc->attr.line_id);
		ret = -EINVAL;
		goto unlock;
	}

	if (test_bit(HTE_TS_REQ, &ei->flags) &&
	    !test_bit(HTE_TS_REGISTERED, &ei->flags)) {
		clear_bit(HTE_TS_REQ, &ei->flags);
		desc->hte_data = NULL;
		ret = 0;
		goto mod_put;
	}

	ret = gdev->chip->ops->release(gdev->chip, desc, ei->xlated_id);
	if (ret) {
		dev_err(gdev->sdev, "id: %d free failed\n",
			desc->attr.line_id);
		goto unlock;
	}

	kfree(ei->line_name);
	if (ei->free_attr_name)
		kfree_const(desc->attr.name);

	debugfs_remove_recursive(ei->ts_dbg_root);

	spin_lock_irqsave(&ei->slock, flag);

	if (test_bit(HTE_TS_QUEUE_WK, &ei->flags)) {
		spin_unlock_irqrestore(&ei->slock, flag);
		flush_work(&ei->cb_work);
		spin_lock_irqsave(&ei->slock, flag);
	}

	atomic_dec(&gdev->ts_req);
	atomic_set(&ei->dropped_ts, 0);

	ei->seq = 1;
	ei->flags = 0;
	desc->hte_data = NULL;

	spin_unlock_irqrestore(&ei->slock, flag);

	ei->cb = NULL;
	ei->tcb = NULL;
	ei->cl_data = NULL;

mod_put:
	module_put(gdev->owner);
unlock:
	mutex_unlock(&ei->req_mlock);
	dev_dbg(gdev->sdev, "release id: %d\n", desc->attr.line_id);

	return ret;
}
EXPORT_SYMBOL_GPL(hte_ts_put);

static int hte_ts_dis_en_common(struct hte_ts_desc *desc, bool en)
{
	u32 ts_id;
	struct hte_device *gdev;
	struct hte_ts_info *ei;
	int ret;
	unsigned long flag;

	if (!desc)
		return -EINVAL;

	ei = desc->hte_data;

	if (!ei || !ei->gdev)
		return -EINVAL;

	gdev = ei->gdev;
	ts_id = desc->attr.line_id;

	mutex_lock(&ei->req_mlock);

	if (!test_bit(HTE_TS_REGISTERED, &ei->flags)) {
		dev_dbg(gdev->sdev, "id:%d is not registered", ts_id);
		ret = -EUSERS;
		goto out;
	}

	spin_lock_irqsave(&ei->slock, flag);

	if (en) {
		if (!test_bit(HTE_TS_DISABLE, &ei->flags)) {
			ret = 0;
			goto out_unlock;
		}

		spin_unlock_irqrestore(&ei->slock, flag);
		ret = gdev->chip->ops->enable(gdev->chip, ei->xlated_id);
		if (ret) {
			dev_warn(gdev->sdev, "id: %d enable failed\n",
				 ts_id);
			goto out;
		}

		spin_lock_irqsave(&ei->slock, flag);
		clear_bit(HTE_TS_DISABLE, &ei->flags);
	} else {
		if (test_bit(HTE_TS_DISABLE, &ei->flags)) {
			ret = 0;
			goto out_unlock;
		}

		spin_unlock_irqrestore(&ei->slock, flag);
		ret = gdev->chip->ops->disable(gdev->chip, ei->xlated_id);
		if (ret) {
			dev_warn(gdev->sdev, "id: %d disable failed\n",
				 ts_id);
			goto out;
		}

		spin_lock_irqsave(&ei->slock, flag);
		set_bit(HTE_TS_DISABLE, &ei->flags);
	}

out_unlock:
	spin_unlock_irqrestore(&ei->slock, flag);
out:
	mutex_unlock(&ei->req_mlock);
	return ret;
}

/**
 * hte_disable_ts() - Disable timestamp on given descriptor.
 *
 * The API does not release any resources associated with desc.
 *
 * @desc: ts descriptor, this is the same as returned by the request API.
 *
 * Context: Holds mutex lock, not suitable from atomic context.
 * Returns: 0 on success or a negative error code on failure.
 */
int hte_disable_ts(struct hte_ts_desc *desc)
{
	return hte_ts_dis_en_common(desc, false);
}
EXPORT_SYMBOL_GPL(hte_disable_ts);

/**
 * hte_enable_ts() - Enable timestamp on given descriptor.
 *
 * @desc: ts descriptor, this is the same as returned by the request API.
 *
 * Context: Holds mutex lock, not suitable from atomic context.
 * Returns: 0 on success or a negative error code on failure.
 */
int hte_enable_ts(struct hte_ts_desc *desc)
{
	return hte_ts_dis_en_common(desc, true);
}
EXPORT_SYMBOL_GPL(hte_enable_ts);

static void hte_do_cb_work(struct work_struct *w)
{
	unsigned long flag;
	struct hte_ts_info *ei = container_of(w, struct hte_ts_info, cb_work);

	if (unlikely(!ei->tcb))
		return;

	ei->tcb(ei->cl_data);

	spin_lock_irqsave(&ei->slock, flag);
	clear_bit(HTE_TS_QUEUE_WK, &ei->flags);
	spin_unlock_irqrestore(&ei->slock, flag);
}

static int __hte_req_ts(struct hte_ts_desc *desc, hte_ts_cb_t cb,
			hte_ts_sec_cb_t tcb, void *data)
{
	int ret;
	struct hte_device *gdev;
	struct hte_ts_info *ei = desc->hte_data;

	gdev = ei->gdev;
	/*
	 * There is a chance that multiple consumers requesting same entity,
	 * lock here.
	 */
	mutex_lock(&ei->req_mlock);

	if (test_bit(HTE_TS_REGISTERED, &ei->flags) ||
	    !test_bit(HTE_TS_REQ, &ei->flags)) {
		dev_dbg(gdev->chip->dev, "id:%u req failed\n",
			desc->attr.line_id);
		ret = -EUSERS;
		goto unlock;
	}

	ei->cb = cb;
	ei->tcb = tcb;
	if (tcb)
		INIT_WORK(&ei->cb_work, hte_do_cb_work);

	ret = gdev->chip->ops->request(gdev->chip, desc, ei->xlated_id);
	if (ret < 0) {
		dev_err(gdev->chip->dev, "ts request failed\n");
		goto unlock;
	}

	ei->cl_data = data;
	ei->seq = 1;

	atomic_inc(&gdev->ts_req);

	if (desc->attr.name)
		ei->line_name = NULL;
	else
		ei->line_name = kasprintf(GFP_KERNEL, "ts_%u", desc->attr.line_id);

	hte_ts_dbgfs_init(desc->attr.name == NULL ?
			  ei->line_name : desc->attr.name, ei);
	set_bit(HTE_TS_REGISTERED, &ei->flags);

	dev_dbg(gdev->chip->dev, "id: %u, xlated id:%u",
		desc->attr.line_id, ei->xlated_id);

	ret = 0;

unlock:
	mutex_unlock(&ei->req_mlock);

	return ret;
}

static int hte_bind_ts_info_locked(struct hte_ts_info *ei,
				   struct hte_ts_desc *desc, u32 x_id)
{
	int ret = 0;

	mutex_lock(&ei->req_mlock);

	if (test_bit(HTE_TS_REQ, &ei->flags)) {
		dev_dbg(ei->gdev->chip->dev, "id:%u is already requested\n",
			desc->attr.line_id);
		ret = -EUSERS;
		goto out;
	}

	set_bit(HTE_TS_REQ, &ei->flags);
	desc->hte_data = ei;
	ei->xlated_id = x_id;

out:
	mutex_unlock(&ei->req_mlock);

	return ret;
}

static struct hte_device *of_node_to_htedevice(struct device_node *np)
{
	struct hte_device *gdev;

	spin_lock(&hte_lock);

	list_for_each_entry(gdev, &hte_devices, list)
		if (gdev->chip && gdev->chip->dev &&
		    device_match_of_node(gdev->chip->dev, np)) {
			spin_unlock(&hte_lock);
			return gdev;
		}

	spin_unlock(&hte_lock);

	return ERR_PTR(-ENODEV);
}

static struct hte_device *hte_find_dev_from_linedata(struct hte_ts_desc *desc)
{
	struct hte_device *gdev;

	spin_lock(&hte_lock);

	list_for_each_entry(gdev, &hte_devices, list)
		if (gdev->chip && gdev->chip->match_from_linedata) {
			if (!gdev->chip->match_from_linedata(gdev->chip, desc))
				continue;
			spin_unlock(&hte_lock);
			return gdev;
		}

	spin_unlock(&hte_lock);

	return ERR_PTR(-ENODEV);
}

/**
 * of_hte_req_count - Return the number of entities to timestamp.
 *
 * The function returns the total count of the requested entities to timestamp
 * by parsing device tree.
 *
 * @dev: The HTE consumer.
 *
 * Returns: Positive number on success, -ENOENT if no entries,
 * -EINVAL for other errors.
 */
int of_hte_req_count(struct device *dev)
{
	int count;

	if (!dev || !dev->of_node)
		return -EINVAL;

	count = of_count_phandle_with_args(dev->of_node, "timestamps",
					   "#timestamp-cells");

	return count ? count : -ENOENT;
}
EXPORT_SYMBOL_GPL(of_hte_req_count);

static inline struct hte_device *hte_get_dev(struct hte_ts_desc *desc)
{
	return hte_find_dev_from_linedata(desc);
}

static struct hte_device *hte_of_get_dev(struct device *dev,
					 struct hte_ts_desc *desc,
					 int index,
					 struct of_phandle_args *args,
					 bool *free_name)
{
	int ret;
	struct device_node *np;
	char *temp;

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

	np = dev->of_node;

	if (!of_property_present(np, "timestamp-names")) {
		/* Let hte core construct it during request time */
		desc->attr.name = NULL;
	} else {
		ret = of_property_read_string_index(np, "timestamp-names",
						    index, &desc->attr.name);
		if (ret) {
			pr_err("can't parse \"timestamp-names\" property\n");
			return ERR_PTR(ret);
		}
		*free_name = false;
		if (desc->attr.name) {
			temp = skip_spaces(desc->attr.name);
			if (!*temp)
				desc->attr.name = NULL;
		}
	}

	ret = of_parse_phandle_with_args(np, "timestamps", "#timestamp-cells",
					 index, args);
	if (ret) {
		pr_err("%s(): can't parse \"timestamps\" property\n",
		       __func__);
		return ERR_PTR(ret);
	}

	of_node_put(args->np);

	return of_node_to_htedevice(args->np);
}

/**
 * hte_ts_get() - The function to initialize and obtain HTE desc.
 *
 * The function initializes the consumer provided HTE descriptor. If consumer
 * has device tree node, index is used to parse the line id and other details.
 * The function needs to be called before using any request APIs.
 *
 * @dev: HTE consumer/client device, used in case of parsing device tree node.
 * @desc: Pre-allocated timestamp descriptor.
 * @index: The index will be used as an index to parse line_id from the
 * device tree node if node is present.
 *
 * Context: Holds mutex lock.
 * Returns: Returns 0 on success or negative error code on failure.
 */
int hte_ts_get(struct device *dev, struct hte_ts_desc *desc, int index)
{
	struct hte_device *gdev;
	struct hte_ts_info *ei;
	const struct fwnode_handle *fwnode;
	struct of_phandle_args args;
	u32 xlated_id;
	int ret;
	bool free_name = false;

	if (!desc)
		return -EINVAL;

	fwnode = dev ? dev_fwnode(dev) : NULL;

	if (is_of_node(fwnode))
		gdev = hte_of_get_dev(dev, desc, index, &args, &free_name);
	else
		gdev = hte_get_dev(desc);

	if (IS_ERR(gdev)) {
		pr_err("%s() no hte dev found\n", __func__);
		return PTR_ERR(gdev);
	}

	if (!try_module_get(gdev->owner))
		return -ENODEV;

	if (!gdev->chip) {
		pr_err("%s(): requested id does not have provider\n",
		       __func__);
		ret = -ENODEV;
		goto put;
	}

	if (is_of_node(fwnode)) {
		if (!gdev->chip->xlate_of)
			ret = -EINVAL;
		else
			ret = gdev->chip->xlate_of(gdev->chip, &args,
						   desc, &xlated_id);
	} else {
		if (!gdev->chip->xlate_plat)
			ret = -EINVAL;
		else
			ret = gdev->chip->xlate_plat(gdev->chip, desc,
						     &xlated_id);
	}

	if (ret < 0)
		goto put;

	ei = &gdev->ei[xlated_id];

	ret = hte_bind_ts_info_locked(ei, desc, xlated_id);
	if (ret)
		goto put;

	ei->free_attr_name = free_name;

	return 0;

put:
	module_put(gdev->owner);
	return ret;
}
EXPORT_SYMBOL_GPL(hte_ts_get);

static void __devm_hte_release_ts(void *res)
{
	hte_ts_put(res);
}

/**
 * hte_request_ts_ns() - The API to request and enable hardware timestamp in
 * nanoseconds.
 *
 * The entity is provider specific for example, GPIO lines, signals, buses
 * etc...The API allocates necessary resources and enables the timestamp.
 *
 * @desc: Pre-allocated and initialized timestamp descriptor.
 * @cb: Callback to push the timestamp data to consumer.
 * @tcb: Optional callback. If its provided, subsystem initializes
 * workqueue. It is called when cb returns HTE_RUN_SECOND_CB.
 * @data: Client data, used during cb and tcb callbacks.
 *
 * Context: Holds mutex lock.
 * Returns: Returns 0 on success or negative error code on failure.
 */
int hte_request_ts_ns(struct hte_ts_desc *desc, hte_ts_cb_t cb,
		      hte_ts_sec_cb_t tcb, void *data)
{
	int ret;
	struct hte_ts_info *ei;

	if (!desc || !desc->hte_data || !cb)
		return -EINVAL;

	ei = desc->hte_data;
	if (!ei || !ei->gdev)
		return -EINVAL;

	ret = __hte_req_ts(desc, cb, tcb, data);
	if (ret < 0) {
		dev_err(ei->gdev->chip->dev,
			"failed to request id: %d\n", desc->attr.line_id);
		return ret;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(hte_request_ts_ns);

/**
 * devm_hte_request_ts_ns() - Resource managed API to request and enable
 * hardware timestamp in nanoseconds.
 *
 * The entity is provider specific for example, GPIO lines, signals, buses
 * etc...The API allocates necessary resources and enables the timestamp. It
 * deallocates and disables automatically when the consumer exits.
 *
 * @dev: HTE consumer/client device.
 * @desc: Pre-allocated and initialized timestamp descriptor.
 * @cb: Callback to push the timestamp data to consumer.
 * @tcb: Optional callback. If its provided, subsystem initializes
 * workqueue. It is called when cb returns HTE_RUN_SECOND_CB.
 * @data: Client data, used during cb and tcb callbacks.
 *
 * Context: Holds mutex lock.
 * Returns: Returns 0 on success or negative error code on failure.
 */
int devm_hte_request_ts_ns(struct device *dev, struct hte_ts_desc *desc,
			   hte_ts_cb_t cb, hte_ts_sec_cb_t tcb,
			   void *data)
{
	int err;

	if (!dev)
		return -EINVAL;

	err = hte_request_ts_ns(desc, cb, tcb, data);
	if (err)
		return err;

	err = devm_add_action_or_reset(dev, __devm_hte_release_ts, desc);
	if (err)
		return err;

	return 0;
}
EXPORT_SYMBOL_GPL(devm_hte_request_ts_ns);

/**
 * hte_init_line_attr() - Initialize line attributes.
 *
 * Zeroes out line attributes and initializes with provided arguments.
 * The function needs to be called before calling any consumer facing
 * functions.
 *
 * @desc: Pre-allocated timestamp descriptor.
 * @line_id: line id.
 * @edge_flags: edge flags related to line_id.
 * @name: name of the line.
 * @data: line data related to line_id.
 *
 * Context: Any.
 * Returns: 0 on success or negative error code for the failure.
 */
int hte_init_line_attr(struct hte_ts_desc *desc, u32 line_id,
		       unsigned long edge_flags, const char *name, void *data)
{
	if (!desc)
		return -EINVAL;

	memset(&desc->attr, 0, sizeof(desc->attr));

	desc->attr.edge_flags = edge_flags;
	desc->attr.line_id = line_id;
	desc->attr.line_data = data;
	if (name) {
		name =  kstrdup_const(name, GFP_KERNEL);
		if (!name)
			return -ENOMEM;
	}

	desc->attr.name = name;

	return 0;
}
EXPORT_SYMBOL_GPL(hte_init_line_attr);

/**
 * hte_get_clk_src_info() - Get the clock source information for a ts
 * descriptor.
 *
 * @desc: ts descriptor, same as returned from request API.
 * @ci: The API fills this structure with the clock information data.
 *
 * Context: Any context.
 * Returns: 0 on success else negative error code on failure.
 */
int hte_get_clk_src_info(const struct hte_ts_desc *desc,
			 struct hte_clk_info *ci)
{
	struct hte_chip *chip;
	struct hte_ts_info *ei;

	if (!desc || !desc->hte_data || !ci) {
		pr_debug("%s:%d\n", __func__, __LINE__);
		return -EINVAL;
	}

	ei = desc->hte_data;
	if (!ei->gdev || !ei->gdev->chip)
		return -EINVAL;

	chip = ei->gdev->chip;
	if (!chip->ops->get_clk_src_info)
		return -EOPNOTSUPP;

	return chip->ops->get_clk_src_info(chip, ci);
}
EXPORT_SYMBOL_GPL(hte_get_clk_src_info);

/**
 * hte_push_ts_ns() - Push timestamp data in nanoseconds.
 *
 * It is used by the provider to push timestamp data.
 *
 * @chip: The HTE chip, used during the registration.
 * @xlated_id: entity id understood by both subsystem and provider, this is
 * obtained from xlate callback during request API.
 * @data: timestamp data.
 *
 * Returns: 0 on success or a negative error code on failure.
 */
int hte_push_ts_ns(const struct hte_chip *chip, u32 xlated_id,
		   struct hte_ts_data *data)
{
	enum hte_return ret;
	int st = 0;
	struct hte_ts_info *ei;
	unsigned long flag;

	if (!chip || !data || !chip->gdev)
		return -EINVAL;

	if (xlated_id >= chip->nlines)
		return -EINVAL;

	ei = &chip->gdev->ei[xlated_id];

	spin_lock_irqsave(&ei->slock, flag);

	/* timestamp sequence counter */
	data->seq = ei->seq++;

	if (!test_bit(HTE_TS_REGISTERED, &ei->flags) ||
	    test_bit(HTE_TS_DISABLE, &ei->flags)) {
		dev_dbg(chip->dev, "Unknown timestamp push\n");
		atomic_inc(&ei->dropped_ts);
		st = -EINVAL;
		goto unlock;
	}

	ret = ei->cb(data, ei->cl_data);
	if (ret == HTE_RUN_SECOND_CB && ei->tcb) {
		queue_work(system_unbound_wq, &ei->cb_work);
		set_bit(HTE_TS_QUEUE_WK, &ei->flags);
	}

unlock:
	spin_unlock_irqrestore(&ei->slock, flag);

	return st;
}
EXPORT_SYMBOL_GPL(hte_push_ts_ns);

static int hte_register_chip(struct hte_chip *chip)
{
	struct hte_device *gdev;
	u32 i;

	if (!chip || !chip->dev || !chip->dev->of_node)
		return -EINVAL;

	if (!chip->ops || !chip->ops->request || !chip->ops->release) {
		dev_err(chip->dev, "Driver needs to provide ops\n");
		return -EINVAL;
	}

	gdev = kzalloc(struct_size(gdev, ei, chip->nlines), GFP_KERNEL);
	if (!gdev)
		return -ENOMEM;

	gdev->chip = chip;
	chip->gdev = gdev;
	gdev->nlines = chip->nlines;
	gdev->sdev = chip->dev;

	for (i = 0; i < chip->nlines; i++) {
		gdev->ei[i].gdev = gdev;
		mutex_init(&gdev->ei[i].req_mlock);
		spin_lock_init(&gdev->ei[i].slock);
	}

	if (chip->dev->driver)
		gdev->owner = chip->dev->driver->owner;
	else
		gdev->owner = THIS_MODULE;

	of_node_get(chip->dev->of_node);

	INIT_LIST_HEAD(&gdev->list);

	spin_lock(&hte_lock);
	list_add_tail(&gdev->list, &hte_devices);
	spin_unlock(&hte_lock);

	hte_chip_dbgfs_init(gdev);

	dev_dbg(chip->dev, "Added hte chip\n");

	return 0;
}

static int hte_unregister_chip(struct hte_chip *chip)
{
	struct hte_device *gdev;

	if (!chip)
		return -EINVAL;

	gdev = chip->gdev;

	spin_lock(&hte_lock);
	list_del(&gdev->list);
	spin_unlock(&hte_lock);

	gdev->chip = NULL;

	of_node_put(chip->dev->of_node);
	debugfs_remove_recursive(gdev->dbg_root);
	kfree(gdev);

	dev_dbg(chip->dev, "Removed hte chip\n");

	return 0;
}

static void _hte_devm_unregister_chip(void *chip)
{
	hte_unregister_chip(chip);
}

/**
 * devm_hte_register_chip() - Resource managed API to register HTE chip.
 *
 * It is used by the provider to register itself with the HTE subsystem.
 * The unregistration is done automatically when the provider exits.
 *
 * @chip: the HTE chip to add to subsystem.
 *
 * Returns: 0 on success or a negative error code on failure.
 */
int devm_hte_register_chip(struct hte_chip *chip)
{
	int err;

	err = hte_register_chip(chip);
	if (err)
		return err;

	err = devm_add_action_or_reset(chip->dev, _hte_devm_unregister_chip,
				       chip);
	if (err)
		return err;

	return 0;
}
EXPORT_SYMBOL_GPL(devm_hte_register_chip);