aboutsummaryrefslogtreecommitdiff
path: root/drivers/perf/arm_dmc620_pmu.c
blob: 66ad5b3ece1974b6b2fd296408b69d87fd0f8682 (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * ARM DMC-620 memory controller PMU driver
 *
 * Copyright (C) 2020 Ampere Computing LLC.
 */

#define DMC620_PMUNAME		"arm_dmc620"
#define DMC620_DRVNAME		DMC620_PMUNAME "_pmu"
#define pr_fmt(fmt)		DMC620_DRVNAME ": " fmt

#include <linux/acpi.h>
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/cpuhotplug.h>
#include <linux/cpumask.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/perf_event.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <linux/rculist.h>
#include <linux/refcount.h>

#define DMC620_PA_SHIFT					12
#define DMC620_CNT_INIT					0x80000000
#define DMC620_CNT_MAX_PERIOD				0xffffffff
#define DMC620_PMU_CLKDIV2_MAX_COUNTERS			8
#define DMC620_PMU_CLK_MAX_COUNTERS			2
#define DMC620_PMU_MAX_COUNTERS				\
	(DMC620_PMU_CLKDIV2_MAX_COUNTERS + DMC620_PMU_CLK_MAX_COUNTERS)

/*
 * The PMU registers start at 0xA00 in the DMC-620 memory map, and these
 * offsets are relative to that base.
 *
 * Each counter has a group of control/value registers, and the
 * DMC620_PMU_COUNTERn offsets are within a counter group.
 *
 * The counter registers groups start at 0xA10.
 */
#define DMC620_PMU_OVERFLOW_STATUS_CLKDIV2		0x8
#define  DMC620_PMU_OVERFLOW_STATUS_CLKDIV2_MASK	\
		(DMC620_PMU_CLKDIV2_MAX_COUNTERS - 1)
#define DMC620_PMU_OVERFLOW_STATUS_CLK			0xC
#define  DMC620_PMU_OVERFLOW_STATUS_CLK_MASK		\
		(DMC620_PMU_CLK_MAX_COUNTERS - 1)
#define DMC620_PMU_COUNTERS_BASE			0x10
#define DMC620_PMU_COUNTERn_MASK_31_00			0x0
#define DMC620_PMU_COUNTERn_MASK_63_32			0x4
#define DMC620_PMU_COUNTERn_MATCH_31_00			0x8
#define DMC620_PMU_COUNTERn_MATCH_63_32			0xC
#define DMC620_PMU_COUNTERn_CONTROL			0x10
#define  DMC620_PMU_COUNTERn_CONTROL_ENABLE		BIT(0)
#define  DMC620_PMU_COUNTERn_CONTROL_INVERT		BIT(1)
#define  DMC620_PMU_COUNTERn_CONTROL_EVENT_MUX		GENMASK(6, 2)
#define  DMC620_PMU_COUNTERn_CONTROL_INCR_MUX		GENMASK(8, 7)
#define DMC620_PMU_COUNTERn_VALUE			0x20
/* Offset of the registers for a given counter, relative to 0xA00 */
#define DMC620_PMU_COUNTERn_OFFSET(n) \
	(DMC620_PMU_COUNTERS_BASE + 0x28 * (n))

static LIST_HEAD(dmc620_pmu_irqs);
static DEFINE_MUTEX(dmc620_pmu_irqs_lock);

struct dmc620_pmu_irq {
	struct hlist_node node;
	struct list_head pmus_node;
	struct list_head irqs_node;
	refcount_t refcount;
	unsigned int irq_num;
	unsigned int cpu;
};

struct dmc620_pmu {
	struct pmu pmu;

	void __iomem *base;
	struct dmc620_pmu_irq *irq;
	struct list_head pmus_node;

	/*
	 * We put all clkdiv2 and clk counters to a same array.
	 * The first DMC620_PMU_CLKDIV2_MAX_COUNTERS bits belong to
	 * clkdiv2 counters, the last DMC620_PMU_CLK_MAX_COUNTERS
	 * belong to clk counters.
	 */
	DECLARE_BITMAP(used_mask, DMC620_PMU_MAX_COUNTERS);
	struct perf_event *events[DMC620_PMU_MAX_COUNTERS];
};

#define to_dmc620_pmu(p) (container_of(p, struct dmc620_pmu, pmu))

static int cpuhp_state_num;

struct dmc620_pmu_event_attr {
	struct device_attribute attr;
	u8 clkdiv2;
	u8 eventid;
};

static ssize_t
dmc620_pmu_event_show(struct device *dev,
			   struct device_attribute *attr, char *page)
{
	struct dmc620_pmu_event_attr *eattr;

	eattr = container_of(attr, typeof(*eattr), attr);

	return sprintf(page, "event=0x%x,clkdiv2=0x%x\n", eattr->eventid, eattr->clkdiv2);
}

#define DMC620_PMU_EVENT_ATTR(_name, _eventid, _clkdiv2)		\
	(&((struct dmc620_pmu_event_attr[]) {{				\
		.attr = __ATTR(_name, 0444, dmc620_pmu_event_show, NULL),	\
		.clkdiv2 = _clkdiv2,						\
		.eventid = _eventid,					\
	}})[0].attr.attr)

static struct attribute *dmc620_pmu_events_attrs[] = {
	/* clkdiv2 events list */
	DMC620_PMU_EVENT_ATTR(clkdiv2_cycle_count, 0x0, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_allocate, 0x1, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_queue_depth, 0x2, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_waiting_for_wr_data, 0x3, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_read_backlog, 0x4, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_waiting_for_mi, 0x5, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_hazard_resolution, 0x6, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_enqueue, 0x7, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_arbitrate, 0x8, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_lrank_turnaround_activate, 0x9, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_prank_turnaround_activate, 0xa, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_read_depth, 0xb, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_write_depth, 0xc, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_highigh_qos_depth, 0xd, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_high_qos_depth, 0xe, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_medium_qos_depth, 0xf, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_low_qos_depth, 0x10, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_activate, 0x11, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_rdwr, 0x12, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_refresh, 0x13, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_training_request, 0x14, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_t_mac_tracker, 0x15, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_bk_fsm_tracker, 0x16, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_bk_open_tracker, 0x17, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_ranks_in_pwr_down, 0x18, 1),
	DMC620_PMU_EVENT_ATTR(clkdiv2_ranks_in_sref, 0x19, 1),

	/* clk events list */
	DMC620_PMU_EVENT_ATTR(clk_cycle_count, 0x0, 0),
	DMC620_PMU_EVENT_ATTR(clk_request, 0x1, 0),
	DMC620_PMU_EVENT_ATTR(clk_upload_stall, 0x2, 0),
	NULL,
};

static const struct attribute_group dmc620_pmu_events_attr_group = {
	.name = "events",
	.attrs = dmc620_pmu_events_attrs,
};

/* User ABI */
#define ATTR_CFG_FLD_mask_CFG		config
#define ATTR_CFG_FLD_mask_LO		0
#define ATTR_CFG_FLD_mask_HI		44
#define ATTR_CFG_FLD_match_CFG		config1
#define ATTR_CFG_FLD_match_LO		0
#define ATTR_CFG_FLD_match_HI		44
#define ATTR_CFG_FLD_invert_CFG		config2
#define ATTR_CFG_FLD_invert_LO		0
#define ATTR_CFG_FLD_invert_HI		0
#define ATTR_CFG_FLD_incr_CFG		config2
#define ATTR_CFG_FLD_incr_LO		1
#define ATTR_CFG_FLD_incr_HI		2
#define ATTR_CFG_FLD_event_CFG		config2
#define ATTR_CFG_FLD_event_LO		3
#define ATTR_CFG_FLD_event_HI		8
#define ATTR_CFG_FLD_clkdiv2_CFG	config2
#define ATTR_CFG_FLD_clkdiv2_LO		9
#define ATTR_CFG_FLD_clkdiv2_HI		9

#define __GEN_PMU_FORMAT_ATTR(cfg, lo, hi)			\
	(lo) == (hi) ? #cfg ":" #lo "\n" : #cfg ":" #lo "-" #hi

#define _GEN_PMU_FORMAT_ATTR(cfg, lo, hi)			\
	__GEN_PMU_FORMAT_ATTR(cfg, lo, hi)

#define GEN_PMU_FORMAT_ATTR(name)				\
	PMU_FORMAT_ATTR(name,					\
	_GEN_PMU_FORMAT_ATTR(ATTR_CFG_FLD_##name##_CFG,		\
			     ATTR_CFG_FLD_##name##_LO,		\
			     ATTR_CFG_FLD_##name##_HI))

#define _ATTR_CFG_GET_FLD(attr, cfg, lo, hi)			\
	((((attr)->cfg) >> lo) & GENMASK_ULL(hi - lo, 0))

#define ATTR_CFG_GET_FLD(attr, name)				\
	_ATTR_CFG_GET_FLD(attr,					\
			  ATTR_CFG_FLD_##name##_CFG,		\
			  ATTR_CFG_FLD_##name##_LO,		\
			  ATTR_CFG_FLD_##name##_HI)

GEN_PMU_FORMAT_ATTR(mask);
GEN_PMU_FORMAT_ATTR(match);
GEN_PMU_FORMAT_ATTR(invert);
GEN_PMU_FORMAT_ATTR(incr);
GEN_PMU_FORMAT_ATTR(event);
GEN_PMU_FORMAT_ATTR(clkdiv2);

static struct attribute *dmc620_pmu_formats_attrs[] = {
	&format_attr_mask.attr,
	&format_attr_match.attr,
	&format_attr_invert.attr,
	&format_attr_incr.attr,
	&format_attr_event.attr,
	&format_attr_clkdiv2.attr,
	NULL,
};

static const struct attribute_group dmc620_pmu_format_attr_group = {
	.name	= "format",
	.attrs	= dmc620_pmu_formats_attrs,
};

static const struct attribute_group *dmc620_pmu_attr_groups[] = {
	&dmc620_pmu_events_attr_group,
	&dmc620_pmu_format_attr_group,
	NULL,
};

static inline
u32 dmc620_pmu_creg_read(struct dmc620_pmu *dmc620_pmu,
			unsigned int idx, unsigned int reg)
{
	return readl(dmc620_pmu->base + DMC620_PMU_COUNTERn_OFFSET(idx) + reg);
}

static inline
void dmc620_pmu_creg_write(struct dmc620_pmu *dmc620_pmu,
			unsigned int idx, unsigned int reg, u32 val)
{
	writel(val, dmc620_pmu->base + DMC620_PMU_COUNTERn_OFFSET(idx) + reg);
}

static
unsigned int dmc620_event_to_counter_control(struct perf_event *event)
{
	struct perf_event_attr *attr = &event->attr;
	unsigned int reg = 0;

	reg |= FIELD_PREP(DMC620_PMU_COUNTERn_CONTROL_INVERT,
			ATTR_CFG_GET_FLD(attr, invert));
	reg |= FIELD_PREP(DMC620_PMU_COUNTERn_CONTROL_EVENT_MUX,
			ATTR_CFG_GET_FLD(attr, event));
	reg |= FIELD_PREP(DMC620_PMU_COUNTERn_CONTROL_INCR_MUX,
			ATTR_CFG_GET_FLD(attr, incr));

	return reg;
}

static int dmc620_get_event_idx(struct perf_event *event)
{
	struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
	int idx, start_idx, end_idx;

	if (ATTR_CFG_GET_FLD(&event->attr, clkdiv2)) {
		start_idx = 0;
		end_idx = DMC620_PMU_CLKDIV2_MAX_COUNTERS;
	} else {
		start_idx = DMC620_PMU_CLKDIV2_MAX_COUNTERS;
		end_idx = DMC620_PMU_MAX_COUNTERS;
	}

	for (idx = start_idx; idx < end_idx; ++idx) {
		if (!test_and_set_bit(idx, dmc620_pmu->used_mask))
			return idx;
	}

	/* The counters are all in use. */
	return -EAGAIN;
}

static inline
u64 dmc620_pmu_read_counter(struct perf_event *event)
{
	struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);

	return dmc620_pmu_creg_read(dmc620_pmu,
				    event->hw.idx, DMC620_PMU_COUNTERn_VALUE);
}

static void dmc620_pmu_event_update(struct perf_event *event)
{
	struct hw_perf_event *hwc = &event->hw;
	u64 delta, prev_count, new_count;

	do {
		/* We may also be called from the irq handler */
		prev_count = local64_read(&hwc->prev_count);
		new_count = dmc620_pmu_read_counter(event);
	} while (local64_cmpxchg(&hwc->prev_count,
			prev_count, new_count) != prev_count);
	delta = (new_count - prev_count) & DMC620_CNT_MAX_PERIOD;
	local64_add(delta, &event->count);
}

static void dmc620_pmu_event_set_period(struct perf_event *event)
{
	struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);

	local64_set(&event->hw.prev_count, DMC620_CNT_INIT);
	dmc620_pmu_creg_write(dmc620_pmu,
			      event->hw.idx, DMC620_PMU_COUNTERn_VALUE, DMC620_CNT_INIT);
}

static void dmc620_pmu_enable_counter(struct perf_event *event)
{
	struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
	u32 reg;

	reg = dmc620_event_to_counter_control(event) | DMC620_PMU_COUNTERn_CONTROL_ENABLE;
	dmc620_pmu_creg_write(dmc620_pmu,
			      event->hw.idx, DMC620_PMU_COUNTERn_CONTROL, reg);
}

static void dmc620_pmu_disable_counter(struct perf_event *event)
{
	struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);

	dmc620_pmu_creg_write(dmc620_pmu,
			      event->hw.idx, DMC620_PMU_COUNTERn_CONTROL, 0);
}

static irqreturn_t dmc620_pmu_handle_irq(int irq_num, void *data)
{
	struct dmc620_pmu_irq *irq = data;
	struct dmc620_pmu *dmc620_pmu;
	irqreturn_t ret = IRQ_NONE;

	rcu_read_lock();
	list_for_each_entry_rcu(dmc620_pmu, &irq->pmus_node, pmus_node) {
		unsigned long status;
		struct perf_event *event;
		unsigned int idx;

		/*
		 * HW doesn't provide a control to atomically disable all counters.
		 * To prevent race condition (overflow happens while clearing status register),
		 * disable all events before continuing
		 */
		for (idx = 0; idx < DMC620_PMU_MAX_COUNTERS; idx++) {
			event = dmc620_pmu->events[idx];
			if (!event)
				continue;
			dmc620_pmu_disable_counter(event);
		}

		status = readl(dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLKDIV2);
		status |= (readl(dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLK) <<
				DMC620_PMU_CLKDIV2_MAX_COUNTERS);
		if (status) {
			for_each_set_bit(idx, &status,
					DMC620_PMU_MAX_COUNTERS) {
				event = dmc620_pmu->events[idx];
				if (WARN_ON_ONCE(!event))
					continue;
				dmc620_pmu_event_update(event);
				dmc620_pmu_event_set_period(event);
			}

			if (status & DMC620_PMU_OVERFLOW_STATUS_CLKDIV2_MASK)
				writel(0, dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLKDIV2);

			if ((status >> DMC620_PMU_CLKDIV2_MAX_COUNTERS) &
				DMC620_PMU_OVERFLOW_STATUS_CLK_MASK)
				writel(0, dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLK);
		}

		for (idx = 0; idx < DMC620_PMU_MAX_COUNTERS; idx++) {
			event = dmc620_pmu->events[idx];
			if (!event)
				continue;
			if (!(event->hw.state & PERF_HES_STOPPED))
				dmc620_pmu_enable_counter(event);
		}

		ret = IRQ_HANDLED;
	}
	rcu_read_unlock();

	return ret;
}

static struct dmc620_pmu_irq *__dmc620_pmu_get_irq(int irq_num)
{
	struct dmc620_pmu_irq *irq;
	int ret;

	list_for_each_entry(irq, &dmc620_pmu_irqs, irqs_node)
		if (irq->irq_num == irq_num && refcount_inc_not_zero(&irq->refcount))
			return irq;

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

	INIT_LIST_HEAD(&irq->pmus_node);

	/* Pick one CPU to be the preferred one to use */
	irq->cpu = raw_smp_processor_id();
	refcount_set(&irq->refcount, 1);

	ret = request_irq(irq_num, dmc620_pmu_handle_irq,
			  IRQF_NOBALANCING | IRQF_NO_THREAD,
			  "dmc620-pmu", irq);
	if (ret)
		goto out_free_aff;

	ret = irq_set_affinity_hint(irq_num, cpumask_of(irq->cpu));
	if (ret)
		goto out_free_irq;

	ret = cpuhp_state_add_instance_nocalls(cpuhp_state_num, &irq->node);
	if (ret)
		goto out_free_irq;

	irq->irq_num = irq_num;
	list_add(&irq->irqs_node, &dmc620_pmu_irqs);

	return irq;

out_free_irq:
	free_irq(irq_num, irq);
out_free_aff:
	kfree(irq);
	return ERR_PTR(ret);
}

static int dmc620_pmu_get_irq(struct dmc620_pmu *dmc620_pmu, int irq_num)
{
	struct dmc620_pmu_irq *irq;

	mutex_lock(&dmc620_pmu_irqs_lock);
	irq = __dmc620_pmu_get_irq(irq_num);
	mutex_unlock(&dmc620_pmu_irqs_lock);

	if (IS_ERR(irq))
		return PTR_ERR(irq);

	dmc620_pmu->irq = irq;
	mutex_lock(&dmc620_pmu_irqs_lock);
	list_add_rcu(&dmc620_pmu->pmus_node, &irq->pmus_node);
	mutex_unlock(&dmc620_pmu_irqs_lock);

	return 0;
}

static void dmc620_pmu_put_irq(struct dmc620_pmu *dmc620_pmu)
{
	struct dmc620_pmu_irq *irq = dmc620_pmu->irq;

	mutex_lock(&dmc620_pmu_irqs_lock);
	list_del_rcu(&dmc620_pmu->pmus_node);

	if (!refcount_dec_and_test(&irq->refcount)) {
		mutex_unlock(&dmc620_pmu_irqs_lock);
		return;
	}

	list_del(&irq->irqs_node);
	mutex_unlock(&dmc620_pmu_irqs_lock);

	WARN_ON(irq_set_affinity_hint(irq->irq_num, NULL));
	free_irq(irq->irq_num, irq);
	cpuhp_state_remove_instance_nocalls(cpuhp_state_num, &irq->node);
	kfree(irq);
}

static int dmc620_pmu_event_init(struct perf_event *event)
{
	struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
	struct hw_perf_event *hwc = &event->hw;
	struct perf_event *sibling;

	if (event->attr.type != event->pmu->type)
		return -ENOENT;

	/*
	 * DMC 620 PMUs are shared across all cpus and cannot
	 * support task bound and sampling events.
	 */
	if (is_sampling_event(event) ||
		event->attach_state & PERF_ATTACH_TASK) {
		dev_dbg(dmc620_pmu->pmu.dev,
			"Can't support per-task counters\n");
		return -EOPNOTSUPP;
	}

	/*
	 * Many perf core operations (eg. events rotation) operate on a
	 * single CPU context. This is obvious for CPU PMUs, where one
	 * expects the same sets of events being observed on all CPUs,
	 * but can lead to issues for off-core PMUs, where each
	 * event could be theoretically assigned to a different CPU. To
	 * mitigate this, we enforce CPU assignment to one, selected
	 * processor.
	 */
	event->cpu = dmc620_pmu->irq->cpu;
	if (event->cpu < 0)
		return -EINVAL;

	/*
	 * We can't atomically disable all HW counters so only one event allowed,
	 * although software events are acceptable.
	 */
	if (event->group_leader != event &&
			!is_software_event(event->group_leader))
		return -EINVAL;

	for_each_sibling_event(sibling, event->group_leader) {
		if (sibling != event &&
				!is_software_event(sibling))
			return -EINVAL;
	}

	hwc->idx = -1;
	return 0;
}

static void dmc620_pmu_read(struct perf_event *event)
{
	dmc620_pmu_event_update(event);
}

static void dmc620_pmu_start(struct perf_event *event, int flags)
{
	event->hw.state = 0;
	dmc620_pmu_event_set_period(event);
	dmc620_pmu_enable_counter(event);
}

static void dmc620_pmu_stop(struct perf_event *event, int flags)
{
	if (event->hw.state & PERF_HES_STOPPED)
		return;

	dmc620_pmu_disable_counter(event);
	dmc620_pmu_event_update(event);
	event->hw.state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
}

static int dmc620_pmu_add(struct perf_event *event, int flags)
{
	struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
	struct perf_event_attr *attr = &event->attr;
	struct hw_perf_event *hwc = &event->hw;
	int idx;
	u64 reg;

	idx = dmc620_get_event_idx(event);
	if (idx < 0)
		return idx;

	hwc->idx = idx;
	dmc620_pmu->events[idx] = event;
	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;

	reg = ATTR_CFG_GET_FLD(attr, mask);
	dmc620_pmu_creg_write(dmc620_pmu,
			      idx, DMC620_PMU_COUNTERn_MASK_31_00, lower_32_bits(reg));
	dmc620_pmu_creg_write(dmc620_pmu,
			      idx, DMC620_PMU_COUNTERn_MASK_63_32, upper_32_bits(reg));

	reg = ATTR_CFG_GET_FLD(attr, match);
	dmc620_pmu_creg_write(dmc620_pmu,
			      idx, DMC620_PMU_COUNTERn_MATCH_31_00, lower_32_bits(reg));
	dmc620_pmu_creg_write(dmc620_pmu,
			      idx, DMC620_PMU_COUNTERn_MATCH_63_32, upper_32_bits(reg));

	if (flags & PERF_EF_START)
		dmc620_pmu_start(event, PERF_EF_RELOAD);

	perf_event_update_userpage(event);
	return 0;
}

static void dmc620_pmu_del(struct perf_event *event, int flags)
{
	struct dmc620_pmu *dmc620_pmu = to_dmc620_pmu(event->pmu);
	struct hw_perf_event *hwc = &event->hw;
	int idx = hwc->idx;

	dmc620_pmu_stop(event, PERF_EF_UPDATE);
	dmc620_pmu->events[idx] = NULL;
	clear_bit(idx, dmc620_pmu->used_mask);
	perf_event_update_userpage(event);
}

static int dmc620_pmu_cpu_teardown(unsigned int cpu,
				   struct hlist_node *node)
{
	struct dmc620_pmu_irq *irq;
	struct dmc620_pmu *dmc620_pmu;
	unsigned int target;

	irq = hlist_entry_safe(node, struct dmc620_pmu_irq, node);
	if (cpu != irq->cpu)
		return 0;

	target = cpumask_any_but(cpu_online_mask, cpu);
	if (target >= nr_cpu_ids)
		return 0;

	/* We're only reading, but this isn't the place to be involving RCU */
	mutex_lock(&dmc620_pmu_irqs_lock);
	list_for_each_entry(dmc620_pmu, &irq->pmus_node, pmus_node)
		perf_pmu_migrate_context(&dmc620_pmu->pmu, irq->cpu, target);
	mutex_unlock(&dmc620_pmu_irqs_lock);

	WARN_ON(irq_set_affinity_hint(irq->irq_num, cpumask_of(target)));
	irq->cpu = target;

	return 0;
}

static int dmc620_pmu_device_probe(struct platform_device *pdev)
{
	struct dmc620_pmu *dmc620_pmu;
	struct resource *res;
	char *name;
	int irq_num;
	int i, ret;

	dmc620_pmu = devm_kzalloc(&pdev->dev,
			sizeof(struct dmc620_pmu), GFP_KERNEL);
	if (!dmc620_pmu)
		return -ENOMEM;

	platform_set_drvdata(pdev, dmc620_pmu);

	dmc620_pmu->pmu = (struct pmu) {
		.module = THIS_MODULE,
		.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
		.task_ctx_nr	= perf_invalid_context,
		.event_init	= dmc620_pmu_event_init,
		.add		= dmc620_pmu_add,
		.del		= dmc620_pmu_del,
		.start		= dmc620_pmu_start,
		.stop		= dmc620_pmu_stop,
		.read		= dmc620_pmu_read,
		.attr_groups	= dmc620_pmu_attr_groups,
	};

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	dmc620_pmu->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(dmc620_pmu->base))
		return PTR_ERR(dmc620_pmu->base);

	/* Make sure device is reset before enabling interrupt */
	for (i = 0; i < DMC620_PMU_MAX_COUNTERS; i++)
		dmc620_pmu_creg_write(dmc620_pmu, i, DMC620_PMU_COUNTERn_CONTROL, 0);
	writel(0, dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLKDIV2);
	writel(0, dmc620_pmu->base + DMC620_PMU_OVERFLOW_STATUS_CLK);

	irq_num = platform_get_irq(pdev, 0);
	if (irq_num < 0)
		return irq_num;

	ret = dmc620_pmu_get_irq(dmc620_pmu, irq_num);
	if (ret)
		return ret;

	name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
				  "%s_%llx", DMC620_PMUNAME,
				  (u64)(res->start >> DMC620_PA_SHIFT));
	if (!name) {
		dev_err(&pdev->dev,
			  "Create name failed, PMU @%pa\n", &res->start);
		goto out_teardown_dev;
	}

	ret = perf_pmu_register(&dmc620_pmu->pmu, name, -1);
	if (ret)
		goto out_teardown_dev;

	return 0;

out_teardown_dev:
	dmc620_pmu_put_irq(dmc620_pmu);
	synchronize_rcu();
	return ret;
}

static int dmc620_pmu_device_remove(struct platform_device *pdev)
{
	struct dmc620_pmu *dmc620_pmu = platform_get_drvdata(pdev);

	dmc620_pmu_put_irq(dmc620_pmu);

	/* perf will synchronise RCU before devres can free dmc620_pmu */
	perf_pmu_unregister(&dmc620_pmu->pmu);

	return 0;
}

static const struct acpi_device_id dmc620_acpi_match[] = {
	{ "ARMHD620", 0},
	{},
};
MODULE_DEVICE_TABLE(acpi, dmc620_acpi_match);
static struct platform_driver dmc620_pmu_driver = {
	.driver	= {
		.name		= DMC620_DRVNAME,
		.acpi_match_table = dmc620_acpi_match,
		.suppress_bind_attrs = true,
	},
	.probe	= dmc620_pmu_device_probe,
	.remove	= dmc620_pmu_device_remove,
};

static int __init dmc620_pmu_init(void)
{
	cpuhp_state_num = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
				      DMC620_DRVNAME,
				      NULL,
				      dmc620_pmu_cpu_teardown);
	if (cpuhp_state_num < 0)
		return cpuhp_state_num;

	return platform_driver_register(&dmc620_pmu_driver);
}

static void __exit dmc620_pmu_exit(void)
{
	platform_driver_unregister(&dmc620_pmu_driver);
	cpuhp_remove_multi_state(cpuhp_state_num);
}

module_init(dmc620_pmu_init);
module_exit(dmc620_pmu_exit);

MODULE_DESCRIPTION("Perf driver for the ARM DMC-620 memory controller");
MODULE_AUTHOR("Tuan Phan <tuanphan@os.amperecomputing.com");
MODULE_LICENSE("GPL v2");