summaryrefslogtreecommitdiff
path: root/arch/x86/kernel/hpet.c
blob: efaf906daf93ff4dcca7385d26047c2db8691fbe (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
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/sysdev.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/hpet.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/pm.h>
#include <linux/io.h>

#include <asm/fixmap.h>
#include <asm/i8253.h>
#include <asm/hpet.h>

#define HPET_MASK			CLOCKSOURCE_MASK(32)

/* FSEC = 10^-15
   NSEC = 10^-9 */
#define FSEC_PER_NSEC			1000000L

#define HPET_DEV_USED_BIT		2
#define HPET_DEV_USED			(1 << HPET_DEV_USED_BIT)
#define HPET_DEV_VALID			0x8
#define HPET_DEV_FSB_CAP		0x1000
#define HPET_DEV_PERI_CAP		0x2000

#define EVT_TO_HPET_DEV(evt) container_of(evt, struct hpet_dev, evt)

/*
 * HPET address is set in acpi/boot.c, when an ACPI entry exists
 */
unsigned long				hpet_address;
u8					hpet_blockid; /* OS timer block num */
u8					hpet_msi_disable;

#ifdef CONFIG_PCI_MSI
static unsigned long			hpet_num_timers;
#endif
static void __iomem			*hpet_virt_address;

struct hpet_dev {
	struct clock_event_device	evt;
	unsigned int			num;
	int				cpu;
	unsigned int			irq;
	unsigned int			flags;
	char				name[10];
};

inline unsigned int hpet_readl(unsigned int a)
{
	return readl(hpet_virt_address + a);
}

static inline void hpet_writel(unsigned int d, unsigned int a)
{
	writel(d, hpet_virt_address + a);
}

#ifdef CONFIG_X86_64
#include <asm/pgtable.h>
#endif

static inline void hpet_set_mapping(void)
{
	hpet_virt_address = ioremap_nocache(hpet_address, HPET_MMAP_SIZE);
#ifdef CONFIG_X86_64
	__set_fixmap(VSYSCALL_HPET, hpet_address, PAGE_KERNEL_VSYSCALL_NOCACHE);
#endif
}

static inline void hpet_clear_mapping(void)
{
	iounmap(hpet_virt_address);
	hpet_virt_address = NULL;
}

/*
 * HPET command line enable / disable
 */
static int boot_hpet_disable;
int hpet_force_user;
static int hpet_verbose;

static int __init hpet_setup(char *str)
{
	if (str) {
		if (!strncmp("disable", str, 7))
			boot_hpet_disable = 1;
		if (!strncmp("force", str, 5))
			hpet_force_user = 1;
		if (!strncmp("verbose", str, 7))
			hpet_verbose = 1;
	}
	return 1;
}
__setup("hpet=", hpet_setup);

static int __init disable_hpet(char *str)
{
	boot_hpet_disable = 1;
	return 1;
}
__setup("nohpet", disable_hpet);

static inline int is_hpet_capable(void)
{
	return !boot_hpet_disable && hpet_address;
}

/*
 * HPET timer interrupt enable / disable
 */
static int hpet_legacy_int_enabled;

/**
 * is_hpet_enabled - check whether the hpet timer interrupt is enabled
 */
int is_hpet_enabled(void)
{
	return is_hpet_capable() && hpet_legacy_int_enabled;
}
EXPORT_SYMBOL_GPL(is_hpet_enabled);

static void _hpet_print_config(const char *function, int line)
{
	u32 i, timers, l, h;
	printk(KERN_INFO "hpet: %s(%d):\n", function, line);
	l = hpet_readl(HPET_ID);
	h = hpet_readl(HPET_PERIOD);
	timers = ((l & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT) + 1;
	printk(KERN_INFO "hpet: ID: 0x%x, PERIOD: 0x%x\n", l, h);
	l = hpet_readl(HPET_CFG);
	h = hpet_readl(HPET_STATUS);
	printk(KERN_INFO "hpet: CFG: 0x%x, STATUS: 0x%x\n", l, h);
	l = hpet_readl(HPET_COUNTER);
	h = hpet_readl(HPET_COUNTER+4);
	printk(KERN_INFO "hpet: COUNTER_l: 0x%x, COUNTER_h: 0x%x\n", l, h);

	for (i = 0; i < timers; i++) {
		l = hpet_readl(HPET_Tn_CFG(i));
		h = hpet_readl(HPET_Tn_CFG(i)+4);
		printk(KERN_INFO "hpet: T%d: CFG_l: 0x%x, CFG_h: 0x%x\n",
		       i, l, h);
		l = hpet_readl(HPET_Tn_CMP(i));
		h = hpet_readl(HPET_Tn_CMP(i)+4);
		printk(KERN_INFO "hpet: T%d: CMP_l: 0x%x, CMP_h: 0x%x\n",
		       i, l, h);
		l = hpet_readl(HPET_Tn_ROUTE(i));
		h = hpet_readl(HPET_Tn_ROUTE(i)+4);
		printk(KERN_INFO "hpet: T%d ROUTE_l: 0x%x, ROUTE_h: 0x%x\n",
		       i, l, h);
	}
}

#define hpet_print_config()					\
do {								\
	if (hpet_verbose)					\
		_hpet_print_config(__FUNCTION__, __LINE__);	\
} while (0)

/*
 * When the hpet driver (/dev/hpet) is enabled, we need to reserve
 * timer 0 and timer 1 in case of RTC emulation.
 */
#ifdef CONFIG_HPET

static void hpet_reserve_msi_timers(struct hpet_data *hd);

static void hpet_reserve_platform_timers(unsigned int id)
{
	struct hpet __iomem *hpet = hpet_virt_address;
	struct hpet_timer __iomem *timer = &hpet->hpet_timers[2];
	unsigned int nrtimers, i;
	struct hpet_data hd;

	nrtimers = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT) + 1;

	memset(&hd, 0, sizeof(hd));
	hd.hd_phys_address	= hpet_address;
	hd.hd_address		= hpet;
	hd.hd_nirqs		= nrtimers;
	hpet_reserve_timer(&hd, 0);

#ifdef CONFIG_HPET_EMULATE_RTC
	hpet_reserve_timer(&hd, 1);
#endif

	/*
	 * NOTE that hd_irq[] reflects IOAPIC input pins (LEGACY_8254
	 * is wrong for i8259!) not the output IRQ.  Many BIOS writers
	 * don't bother configuring *any* comparator interrupts.
	 */
	hd.hd_irq[0] = HPET_LEGACY_8254;
	hd.hd_irq[1] = HPET_LEGACY_RTC;

	for (i = 2; i < nrtimers; timer++, i++) {
		hd.hd_irq[i] = (readl(&timer->hpet_config) &
			Tn_INT_ROUTE_CNF_MASK) >> Tn_INT_ROUTE_CNF_SHIFT;
	}

	hpet_reserve_msi_timers(&hd);

	hpet_alloc(&hd);

}
#else
static void hpet_reserve_platform_timers(unsigned int id) { }
#endif

/*
 * Common hpet info
 */
static unsigned long hpet_period;

static void hpet_legacy_set_mode(enum clock_event_mode mode,
			  struct clock_event_device *evt);
static int hpet_legacy_next_event(unsigned long delta,
			   struct clock_event_device *evt);

/*
 * The hpet clock event device
 */
static struct clock_event_device hpet_clockevent = {
	.name		= "hpet",
	.features	= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
	.set_mode	= hpet_legacy_set_mode,
	.set_next_event = hpet_legacy_next_event,
	.shift		= 32,
	.irq		= 0,
	.rating		= 50,
};

static void hpet_stop_counter(void)
{
	unsigned long cfg = hpet_readl(HPET_CFG);
	cfg &= ~HPET_CFG_ENABLE;
	hpet_writel(cfg, HPET_CFG);
}

static void hpet_reset_counter(void)
{
	hpet_writel(0, HPET_COUNTER);
	hpet_writel(0, HPET_COUNTER + 4);
}

static void hpet_start_counter(void)
{
	unsigned int cfg = hpet_readl(HPET_CFG);
	cfg |= HPET_CFG_ENABLE;
	hpet_writel(cfg, HPET_CFG);
}

static void hpet_restart_counter(void)
{
	hpet_stop_counter();
	hpet_reset_counter();
	hpet_start_counter();
}

static void hpet_resume_device(void)
{
	force_hpet_resume();
}

static void hpet_resume_counter(struct clocksource *cs)
{
	hpet_resume_device();
	hpet_restart_counter();
}

static void hpet_enable_legacy_int(void)
{
	unsigned int cfg = hpet_readl(HPET_CFG);

	cfg |= HPET_CFG_LEGACY;
	hpet_writel(cfg, HPET_CFG);
	hpet_legacy_int_enabled = 1;
}

static void hpet_legacy_clockevent_register(void)
{
	/* Start HPET legacy interrupts */
	hpet_enable_legacy_int();

	/*
	 * The mult factor is defined as (include/linux/clockchips.h)
	 *  mult/2^shift = cyc/ns (in contrast to ns/cyc in clocksource.h)
	 * hpet_period is in units of femtoseconds (per cycle), so
	 *  mult/2^shift = cyc/ns = 10^6/hpet_period
	 *  mult = (10^6 * 2^shift)/hpet_period
	 *  mult = (FSEC_PER_NSEC << hpet_clockevent.shift)/hpet_period
	 */
	hpet_clockevent.mult = div_sc((unsigned long) FSEC_PER_NSEC,
				      hpet_period, hpet_clockevent.shift);
	/* Calculate the min / max delta */
	hpet_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFFFF,
							   &hpet_clockevent);
	/* 5 usec minimum reprogramming delta. */
	hpet_clockevent.min_delta_ns = 5000;

	/*
	 * Start hpet with the boot cpu mask and make it
	 * global after the IO_APIC has been initialized.
	 */
	hpet_clockevent.cpumask = cpumask_of(smp_processor_id());
	clockevents_register_device(&hpet_clockevent);
	global_clock_event = &hpet_clockevent;
	printk(KERN_DEBUG "hpet clockevent registered\n");
}

static int hpet_setup_msi_irq(unsigned int irq);

static void hpet_set_mode(enum clock_event_mode mode,
			  struct clock_event_device *evt, int timer)
{
	unsigned int cfg, cmp, now;
	uint64_t delta;

	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
		hpet_stop_counter();
		delta = ((uint64_t)(NSEC_PER_SEC/HZ)) * evt->mult;
		delta >>= evt->shift;
		now = hpet_readl(HPET_COUNTER);
		cmp = now + (unsigned int) delta;
		cfg = hpet_readl(HPET_Tn_CFG(timer));
		/* Make sure we use edge triggered interrupts */
		cfg &= ~HPET_TN_LEVEL;
		cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC |
		       HPET_TN_SETVAL | HPET_TN_32BIT;
		hpet_writel(cfg, HPET_Tn_CFG(timer));
		hpet_writel(cmp, HPET_Tn_CMP(timer));
		udelay(1);
		/*
		 * HPET on AMD 81xx needs a second write (with HPET_TN_SETVAL
		 * cleared) to T0_CMP to set the period. The HPET_TN_SETVAL
		 * bit is automatically cleared after the first write.
		 * (See AMD-8111 HyperTransport I/O Hub Data Sheet,
		 * Publication # 24674)
		 */
		hpet_writel((unsigned int) delta, HPET_Tn_CMP(timer));
		hpet_start_counter();
		hpet_print_config();
		break;

	case CLOCK_EVT_MODE_ONESHOT:
		cfg = hpet_readl(HPET_Tn_CFG(timer));
		cfg &= ~HPET_TN_PERIODIC;
		cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
		hpet_writel(cfg, HPET_Tn_CFG(timer));
		break;

	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
		cfg = hpet_readl(HPET_Tn_CFG(timer));
		cfg &= ~HPET_TN_ENABLE;
		hpet_writel(cfg, HPET_Tn_CFG(timer));
		break;

	case CLOCK_EVT_MODE_RESUME:
		if (timer == 0) {
			hpet_enable_legacy_int();
		} else {
			struct hpet_dev *hdev = EVT_TO_HPET_DEV(evt);
			hpet_setup_msi_irq(hdev->irq);
			disable_irq(hdev->irq);
			irq_set_affinity(hdev->irq, cpumask_of(hdev->cpu));
			enable_irq(hdev->irq);
		}
		hpet_print_config();
		break;
	}
}

static int hpet_next_event(unsigned long delta,
			   struct clock_event_device *evt, int timer)
{
	u32 cnt;

	cnt = hpet_readl(HPET_COUNTER);
	cnt += (u32) delta;
	hpet_writel(cnt, HPET_Tn_CMP(timer));

	/*
	 * We need to read back the CMP register on certain HPET
	 * implementations (ATI chipsets) which seem to delay the
	 * transfer of the compare register into the internal compare
	 * logic. With small deltas this might actually be too late as
	 * the counter could already be higher than the compare value
	 * at that point and we would wait for the next hpet interrupt
	 * forever. We found out that reading the CMP register back
	 * forces the transfer so we can rely on the comparison with
	 * the counter register below. If the read back from the
	 * compare register does not match the value we programmed
	 * then we might have a real hardware problem. We can not do
	 * much about it here, but at least alert the user/admin with
	 * a prominent warning.
	 *
	 * An erratum on some chipsets (ICH9,..), results in
	 * comparator read immediately following a write returning old
	 * value. Workaround for this is to read this value second
	 * time, when first read returns old value.
	 *
	 * In fact the write to the comparator register is delayed up
	 * to two HPET cycles so the workaround we tried to restrict
	 * the readback to those known to be borked ATI chipsets
	 * failed miserably. So we give up on optimizations forever
	 * and penalize all HPET incarnations unconditionally.
	 */
	if (unlikely((u32)hpet_readl(HPET_Tn_CMP(timer)) != cnt)) {
		if (hpet_readl(HPET_Tn_CMP(timer)) != cnt)
			printk_once(KERN_WARNING
				"hpet: compare register read back failed.\n");
	}

	return (s32)(hpet_readl(HPET_COUNTER) - cnt) >= 0 ? -ETIME : 0;
}

static void hpet_legacy_set_mode(enum clock_event_mode mode,
			struct clock_event_device *evt)
{
	hpet_set_mode(mode, evt, 0);
}

static int hpet_legacy_next_event(unsigned long delta,
			struct clock_event_device *evt)
{
	return hpet_next_event(delta, evt, 0);
}

/*
 * HPET MSI Support
 */
#ifdef CONFIG_PCI_MSI

static DEFINE_PER_CPU(struct hpet_dev *, cpu_hpet_dev);
static struct hpet_dev	*hpet_devs;

void hpet_msi_unmask(struct irq_data *data)
{
	struct hpet_dev *hdev = data->handler_data;
	unsigned int cfg;

	/* unmask it */
	cfg = hpet_readl(HPET_Tn_CFG(hdev->num));
	cfg |= HPET_TN_FSB;
	hpet_writel(cfg, HPET_Tn_CFG(hdev->num));
}

void hpet_msi_mask(struct irq_data *data)
{
	struct hpet_dev *hdev = data->handler_data;
	unsigned int cfg;

	/* mask it */
	cfg = hpet_readl(HPET_Tn_CFG(hdev->num));
	cfg &= ~HPET_TN_FSB;
	hpet_writel(cfg, HPET_Tn_CFG(hdev->num));
}

void hpet_msi_write(struct hpet_dev *hdev, struct msi_msg *msg)
{
	hpet_writel(msg->data, HPET_Tn_ROUTE(hdev->num));
	hpet_writel(msg->address_lo, HPET_Tn_ROUTE(hdev->num) + 4);
}

void hpet_msi_read(struct hpet_dev *hdev, struct msi_msg *msg)
{
	msg->data = hpet_readl(HPET_Tn_ROUTE(hdev->num));
	msg->address_lo = hpet_readl(HPET_Tn_ROUTE(hdev->num) + 4);
	msg->address_hi = 0;
}

static void hpet_msi_set_mode(enum clock_event_mode mode,
				struct clock_event_device *evt)
{
	struct hpet_dev *hdev = EVT_TO_HPET_DEV(evt);
	hpet_set_mode(mode, evt, hdev->num);
}

static int hpet_msi_next_event(unsigned long delta,
				struct clock_event_device *evt)
{
	struct hpet_dev *hdev = EVT_TO_HPET_DEV(evt);
	return hpet_next_event(delta, evt, hdev->num);
}

static int hpet_setup_msi_irq(unsigned int irq)
{
	if (arch_setup_hpet_msi(irq, hpet_blockid)) {
		destroy_irq(irq);
		return -EINVAL;
	}
	return 0;
}

static int hpet_assign_irq(struct hpet_dev *dev)
{
	unsigned int irq;

	irq = create_irq_nr(0, -1);
	if (!irq)
		return -EINVAL;

	set_irq_data(irq, dev);

	if (hpet_setup_msi_irq(irq))
		return -EINVAL;

	dev->irq = irq;
	return 0;
}

static irqreturn_t hpet_interrupt_handler(int irq, void *data)
{
	struct hpet_dev *dev = (struct hpet_dev *)data;
	struct clock_event_device *hevt = &dev->evt;

	if (!hevt->event_handler) {
		printk(KERN_INFO "Spurious HPET timer interrupt on HPET timer %d\n",
				dev->num);
		return IRQ_HANDLED;
	}

	hevt->event_handler(hevt);
	return IRQ_HANDLED;
}

static int hpet_setup_irq(struct hpet_dev *dev)
{

	if (request_irq(dev->irq, hpet_interrupt_handler,
			IRQF_TIMER | IRQF_DISABLED | IRQF_NOBALANCING,
			dev->name, dev))
		return -1;

	disable_irq(dev->irq);
	irq_set_affinity(dev->irq, cpumask_of(dev->cpu));
	enable_irq(dev->irq);

	printk(KERN_DEBUG "hpet: %s irq %d for MSI\n",
			 dev->name, dev->irq);

	return 0;
}

/* This should be called in specific @cpu */
static void init_one_hpet_msi_clockevent(struct hpet_dev *hdev, int cpu)
{
	struct clock_event_device *evt = &hdev->evt;
	uint64_t hpet_freq;

	WARN_ON(cpu != smp_processor_id());
	if (!(hdev->flags & HPET_DEV_VALID))
		return;

	if (hpet_setup_msi_irq(hdev->irq))
		return;

	hdev->cpu = cpu;
	per_cpu(cpu_hpet_dev, cpu) = hdev;
	evt->name = hdev->name;
	hpet_setup_irq(hdev);
	evt->irq = hdev->irq;

	evt->rating = 110;
	evt->features = CLOCK_EVT_FEAT_ONESHOT;
	if (hdev->flags & HPET_DEV_PERI_CAP)
		evt->features |= CLOCK_EVT_FEAT_PERIODIC;

	evt->set_mode = hpet_msi_set_mode;
	evt->set_next_event = hpet_msi_next_event;
	evt->shift = 32;

	/*
	 * The period is a femto seconds value. We need to calculate the
	 * scaled math multiplication factor for nanosecond to hpet tick
	 * conversion.
	 */
	hpet_freq = FSEC_PER_SEC;
	do_div(hpet_freq, hpet_period);
	evt->mult = div_sc((unsigned long) hpet_freq,
				      NSEC_PER_SEC, evt->shift);
	/* Calculate the max delta */
	evt->max_delta_ns = clockevent_delta2ns(0x7FFFFFFF, evt);
	/* 5 usec minimum reprogramming delta. */
	evt->min_delta_ns = 5000;

	evt->cpumask = cpumask_of(hdev->cpu);
	clockevents_register_device(evt);
}

#ifdef CONFIG_HPET
/* Reserve at least one timer for userspace (/dev/hpet) */
#define RESERVE_TIMERS 1
#else
#define RESERVE_TIMERS 0
#endif

static void hpet_msi_capability_lookup(unsigned int start_timer)
{
	unsigned int id;
	unsigned int num_timers;
	unsigned int num_timers_used = 0;
	int i;

	if (hpet_msi_disable)
		return;

	if (boot_cpu_has(X86_FEATURE_ARAT))
		return;
	id = hpet_readl(HPET_ID);

	num_timers = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT);
	num_timers++; /* Value read out starts from 0 */
	hpet_print_config();

	hpet_devs = kzalloc(sizeof(struct hpet_dev) * num_timers, GFP_KERNEL);
	if (!hpet_devs)
		return;

	hpet_num_timers = num_timers;

	for (i = start_timer; i < num_timers - RESERVE_TIMERS; i++) {
		struct hpet_dev *hdev = &hpet_devs[num_timers_used];
		unsigned int cfg = hpet_readl(HPET_Tn_CFG(i));

		/* Only consider HPET timer with MSI support */
		if (!(cfg & HPET_TN_FSB_CAP))
			continue;

		hdev->flags = 0;
		if (cfg & HPET_TN_PERIODIC_CAP)
			hdev->flags |= HPET_DEV_PERI_CAP;
		hdev->num = i;

		sprintf(hdev->name, "hpet%d", i);
		if (hpet_assign_irq(hdev))
			continue;

		hdev->flags |= HPET_DEV_FSB_CAP;
		hdev->flags |= HPET_DEV_VALID;
		num_timers_used++;
		if (num_timers_used == num_possible_cpus())
			break;
	}

	printk(KERN_INFO "HPET: %d timers in total, %d timers will be used for per-cpu timer\n",
		num_timers, num_timers_used);
}

#ifdef CONFIG_HPET
static void hpet_reserve_msi_timers(struct hpet_data *hd)
{
	int i;

	if (!hpet_devs)
		return;

	for (i = 0; i < hpet_num_timers; i++) {
		struct hpet_dev *hdev = &hpet_devs[i];

		if (!(hdev->flags & HPET_DEV_VALID))
			continue;

		hd->hd_irq[hdev->num] = hdev->irq;
		hpet_reserve_timer(hd, hdev->num);
	}
}
#endif

static struct hpet_dev *hpet_get_unused_timer(void)
{
	int i;

	if (!hpet_devs)
		return NULL;

	for (i = 0; i < hpet_num_timers; i++) {
		struct hpet_dev *hdev = &hpet_devs[i];

		if (!(hdev->flags & HPET_DEV_VALID))
			continue;
		if (test_and_set_bit(HPET_DEV_USED_BIT,
			(unsigned long *)&hdev->flags))
			continue;
		return hdev;
	}
	return NULL;
}

struct hpet_work_struct {
	struct delayed_work work;
	struct completion complete;
};

static void hpet_work(struct work_struct *w)
{
	struct hpet_dev *hdev;
	int cpu = smp_processor_id();
	struct hpet_work_struct *hpet_work;

	hpet_work = container_of(w, struct hpet_work_struct, work.work);

	hdev = hpet_get_unused_timer();
	if (hdev)
		init_one_hpet_msi_clockevent(hdev, cpu);

	complete(&hpet_work->complete);
}

static int hpet_cpuhp_notify(struct notifier_block *n,
		unsigned long action, void *hcpu)
{
	unsigned long cpu = (unsigned long)hcpu;
	struct hpet_work_struct work;
	struct hpet_dev *hdev = per_cpu(cpu_hpet_dev, cpu);

	switch (action & 0xf) {
	case CPU_ONLINE:
		INIT_DELAYED_WORK_ON_STACK(&work.work, hpet_work);
		init_completion(&work.complete);
		/* FIXME: add schedule_work_on() */
		schedule_delayed_work_on(cpu, &work.work, 0);
		wait_for_completion(&work.complete);
		destroy_timer_on_stack(&work.work.timer);
		break;
	case CPU_DEAD:
		if (hdev) {
			free_irq(hdev->irq, hdev);
			hdev->flags &= ~HPET_DEV_USED;
			per_cpu(cpu_hpet_dev, cpu) = NULL;
		}
		break;
	}
	return NOTIFY_OK;
}
#else

static int hpet_setup_msi_irq(unsigned int irq)
{
	return 0;
}
static void hpet_msi_capability_lookup(unsigned int start_timer)
{
	return;
}

#ifdef CONFIG_HPET
static void hpet_reserve_msi_timers(struct hpet_data *hd)
{
	return;
}
#endif

static int hpet_cpuhp_notify(struct notifier_block *n,
		unsigned long action, void *hcpu)
{
	return NOTIFY_OK;
}

#endif

/*
 * Clock source related code
 */
static cycle_t read_hpet(struct clocksource *cs)
{
	return (cycle_t)hpet_readl(HPET_COUNTER);
}

#ifdef CONFIG_X86_64
static cycle_t __vsyscall_fn vread_hpet(void)
{
	return readl((const void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0);
}
#endif

static struct clocksource clocksource_hpet = {
	.name		= "hpet",
	.rating		= 250,
	.read		= read_hpet,
	.mask		= HPET_MASK,
	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
	.resume		= hpet_resume_counter,
#ifdef CONFIG_X86_64
	.vread		= vread_hpet,
#endif
};

static int hpet_clocksource_register(void)
{
	u64 start, now;
	u64 hpet_freq;
	cycle_t t1;

	/* Start the counter */
	hpet_restart_counter();

	/* Verify whether hpet counter works */
	t1 = hpet_readl(HPET_COUNTER);
	rdtscll(start);

	/*
	 * We don't know the TSC frequency yet, but waiting for
	 * 200000 TSC cycles is safe:
	 * 4 GHz == 50us
	 * 1 GHz == 200us
	 */
	do {
		rep_nop();
		rdtscll(now);
	} while ((now - start) < 200000UL);

	if (t1 == hpet_readl(HPET_COUNTER)) {
		printk(KERN_WARNING
		       "HPET counter not counting. HPET disabled\n");
		return -ENODEV;
	}

	/*
	 * The definition of mult is (include/linux/clocksource.h)
	 * mult/2^shift = ns/cyc and hpet_period is in units of fsec/cyc
	 * so we first need to convert hpet_period to ns/cyc units:
	 *  mult/2^shift = ns/cyc = hpet_period/10^6
	 *  mult = (hpet_period * 2^shift)/10^6
	 *  mult = (hpet_period << shift)/FSEC_PER_NSEC
	 */

	/* Need to convert hpet_period (fsec/cyc) to cyc/sec:
	 *
	 * cyc/sec = FSEC_PER_SEC/hpet_period(fsec/cyc)
	 * cyc/sec = (FSEC_PER_NSEC * NSEC_PER_SEC)/hpet_period
	 */
	hpet_freq = FSEC_PER_SEC;
	do_div(hpet_freq, hpet_period);
	clocksource_register_hz(&clocksource_hpet, (u32)hpet_freq);

	return 0;
}

/**
 * hpet_enable - Try to setup the HPET timer. Returns 1 on success.
 */
int __init hpet_enable(void)
{
	unsigned int id;
	int i;

	if (!is_hpet_capable())
		return 0;

	hpet_set_mapping();

	/*
	 * Read the period and check for a sane value:
	 */
	hpet_period = hpet_readl(HPET_PERIOD);

	/*
	 * AMD SB700 based systems with spread spectrum enabled use a
	 * SMM based HPET emulation to provide proper frequency
	 * setting. The SMM code is initialized with the first HPET
	 * register access and takes some time to complete. During
	 * this time the config register reads 0xffffffff. We check
	 * for max. 1000 loops whether the config register reads a non
	 * 0xffffffff value to make sure that HPET is up and running
	 * before we go further. A counting loop is safe, as the HPET
	 * access takes thousands of CPU cycles. On non SB700 based
	 * machines this check is only done once and has no side
	 * effects.
	 */
	for (i = 0; hpet_readl(HPET_CFG) == 0xFFFFFFFF; i++) {
		if (i == 1000) {
			printk(KERN_WARNING
			       "HPET config register value = 0xFFFFFFFF. "
			       "Disabling HPET\n");
			goto out_nohpet;
		}
	}

	if (hpet_period < HPET_MIN_PERIOD || hpet_period > HPET_MAX_PERIOD)
		goto out_nohpet;

	/*
	 * Read the HPET ID register to retrieve the IRQ routing
	 * information and the number of channels
	 */
	id = hpet_readl(HPET_ID);
	hpet_print_config();

#ifdef CONFIG_HPET_EMULATE_RTC
	/*
	 * The legacy routing mode needs at least two channels, tick timer
	 * and the rtc emulation channel.
	 */
	if (!(id & HPET_ID_NUMBER))
		goto out_nohpet;
#endif

	if (hpet_clocksource_register())
		goto out_nohpet;

	if (id & HPET_ID_LEGSUP) {
		hpet_legacy_clockevent_register();
		return 1;
	}
	return 0;

out_nohpet:
	hpet_clear_mapping();
	hpet_address = 0;
	return 0;
}

/*
 * Needs to be late, as the reserve_timer code calls kalloc !
 *
 * Not a problem on i386 as hpet_enable is called from late_time_init,
 * but on x86_64 it is necessary !
 */
static __init int hpet_late_init(void)
{
	int cpu;

	if (boot_hpet_disable)
		return -ENODEV;

	if (!hpet_address) {
		if (!force_hpet_address)
			return -ENODEV;

		hpet_address = force_hpet_address;
		hpet_enable();
	}

	if (!hpet_virt_address)
		return -ENODEV;

	if (hpet_readl(HPET_ID) & HPET_ID_LEGSUP)
		hpet_msi_capability_lookup(2);
	else
		hpet_msi_capability_lookup(0);

	hpet_reserve_platform_timers(hpet_readl(HPET_ID));
	hpet_print_config();

	if (hpet_msi_disable)
		return 0;

	if (boot_cpu_has(X86_FEATURE_ARAT))
		return 0;

	for_each_online_cpu(cpu) {
		hpet_cpuhp_notify(NULL, CPU_ONLINE, (void *)(long)cpu);
	}

	/* This notifier should be called after workqueue is ready */
	hotcpu_notifier(hpet_cpuhp_notify, -20);

	return 0;
}
fs_initcall(hpet_late_init);

void hpet_disable(void)
{
	if (is_hpet_capable() && hpet_virt_address) {
		unsigned int cfg = hpet_readl(HPET_CFG);

		if (hpet_legacy_int_enabled) {
			cfg &= ~HPET_CFG_LEGACY;
			hpet_legacy_int_enabled = 0;
		}
		cfg &= ~HPET_CFG_ENABLE;
		hpet_writel(cfg, HPET_CFG);
	}
}

#ifdef CONFIG_HPET_EMULATE_RTC

/* HPET in LegacyReplacement Mode eats up RTC interrupt line. When, HPET
 * is enabled, we support RTC interrupt functionality in software.
 * RTC has 3 kinds of interrupts:
 * 1) Update Interrupt - generate an interrupt, every sec, when RTC clock
 *    is updated
 * 2) Alarm Interrupt - generate an interrupt at a specific time of day
 * 3) Periodic Interrupt - generate periodic interrupt, with frequencies
 *    2Hz-8192Hz (2Hz-64Hz for non-root user) (all freqs in powers of 2)
 * (1) and (2) above are implemented using polling at a frequency of
 * 64 Hz. The exact frequency is a tradeoff between accuracy and interrupt
 * overhead. (DEFAULT_RTC_INT_FREQ)
 * For (3), we use interrupts at 64Hz or user specified periodic
 * frequency, whichever is higher.
 */
#include <linux/mc146818rtc.h>
#include <linux/rtc.h>
#include <asm/rtc.h>

#define DEFAULT_RTC_INT_FREQ	64
#define DEFAULT_RTC_SHIFT	6
#define RTC_NUM_INTS		1

static unsigned long hpet_rtc_flags;
static int hpet_prev_update_sec;
static struct rtc_time hpet_alarm_time;
static unsigned long hpet_pie_count;
static u32 hpet_t1_cmp;
static u32 hpet_default_delta;
static u32 hpet_pie_delta;
static unsigned long hpet_pie_limit;

static rtc_irq_handler irq_handler;

/*
 * Check that the hpet counter c1 is ahead of the c2
 */
static inline int hpet_cnt_ahead(u32 c1, u32 c2)
{
	return (s32)(c2 - c1) < 0;
}

/*
 * Registers a IRQ handler.
 */
int hpet_register_irq_handler(rtc_irq_handler handler)
{
	if (!is_hpet_enabled())
		return -ENODEV;
	if (irq_handler)
		return -EBUSY;

	irq_handler = handler;

	return 0;
}
EXPORT_SYMBOL_GPL(hpet_register_irq_handler);

/*
 * Deregisters the IRQ handler registered with hpet_register_irq_handler()
 * and does cleanup.
 */
void hpet_unregister_irq_handler(rtc_irq_handler handler)
{
	if (!is_hpet_enabled())
		return;

	irq_handler = NULL;
	hpet_rtc_flags = 0;
}
EXPORT_SYMBOL_GPL(hpet_unregister_irq_handler);

/*
 * Timer 1 for RTC emulation. We use one shot mode, as periodic mode
 * is not supported by all HPET implementations for timer 1.
 *
 * hpet_rtc_timer_init() is called when the rtc is initialized.
 */
int hpet_rtc_timer_init(void)
{
	unsigned int cfg, cnt, delta;
	unsigned long flags;

	if (!is_hpet_enabled())
		return 0;

	if (!hpet_default_delta) {
		uint64_t clc;

		clc = (uint64_t) hpet_clockevent.mult * NSEC_PER_SEC;
		clc >>= hpet_clockevent.shift + DEFAULT_RTC_SHIFT;
		hpet_default_delta = clc;
	}

	if (!(hpet_rtc_flags & RTC_PIE) || hpet_pie_limit)
		delta = hpet_default_delta;
	else
		delta = hpet_pie_delta;

	local_irq_save(flags);

	cnt = delta + hpet_readl(HPET_COUNTER);
	hpet_writel(cnt, HPET_T1_CMP);
	hpet_t1_cmp = cnt;

	cfg = hpet_readl(HPET_T1_CFG);
	cfg &= ~HPET_TN_PERIODIC;
	cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
	hpet_writel(cfg, HPET_T1_CFG);

	local_irq_restore(flags);

	return 1;
}
EXPORT_SYMBOL_GPL(hpet_rtc_timer_init);

/*
 * The functions below are called from rtc driver.
 * Return 0 if HPET is not being used.
 * Otherwise do the necessary changes and return 1.
 */
int hpet_mask_rtc_irq_bit(unsigned long bit_mask)
{
	if (!is_hpet_enabled())
		return 0;

	hpet_rtc_flags &= ~bit_mask;
	return 1;
}
EXPORT_SYMBOL_GPL(hpet_mask_rtc_irq_bit);

int hpet_set_rtc_irq_bit(unsigned long bit_mask)
{
	unsigned long oldbits = hpet_rtc_flags;

	if (!is_hpet_enabled())
		return 0;

	hpet_rtc_flags |= bit_mask;

	if ((bit_mask & RTC_UIE) && !(oldbits & RTC_UIE))
		hpet_prev_update_sec = -1;

	if (!oldbits)
		hpet_rtc_timer_init();

	return 1;
}
EXPORT_SYMBOL_GPL(hpet_set_rtc_irq_bit);

int hpet_set_alarm_time(unsigned char hrs, unsigned char min,
			unsigned char sec)
{
	if (!is_hpet_enabled())
		return 0;

	hpet_alarm_time.tm_hour = hrs;
	hpet_alarm_time.tm_min = min;
	hpet_alarm_time.tm_sec = sec;

	return 1;
}
EXPORT_SYMBOL_GPL(hpet_set_alarm_time);

int hpet_set_periodic_freq(unsigned long freq)
{
	uint64_t clc;

	if (!is_hpet_enabled())
		return 0;

	if (freq <= DEFAULT_RTC_INT_FREQ)
		hpet_pie_limit = DEFAULT_RTC_INT_FREQ / freq;
	else {
		clc = (uint64_t) hpet_clockevent.mult * NSEC_PER_SEC;
		do_div(clc, freq);
		clc >>= hpet_clockevent.shift;
		hpet_pie_delta = clc;
		hpet_pie_limit = 0;
	}
	return 1;
}
EXPORT_SYMBOL_GPL(hpet_set_periodic_freq);

int hpet_rtc_dropped_irq(void)
{
	return is_hpet_enabled();
}
EXPORT_SYMBOL_GPL(hpet_rtc_dropped_irq);

static void hpet_rtc_timer_reinit(void)
{
	unsigned int cfg, delta;
	int lost_ints = -1;

	if (unlikely(!hpet_rtc_flags)) {
		cfg = hpet_readl(HPET_T1_CFG);
		cfg &= ~HPET_TN_ENABLE;
		hpet_writel(cfg, HPET_T1_CFG);
		return;
	}

	if (!(hpet_rtc_flags & RTC_PIE) || hpet_pie_limit)
		delta = hpet_default_delta;
	else
		delta = hpet_pie_delta;

	/*
	 * Increment the comparator value until we are ahead of the
	 * current count.
	 */
	do {
		hpet_t1_cmp += delta;
		hpet_writel(hpet_t1_cmp, HPET_T1_CMP);
		lost_ints++;
	} while (!hpet_cnt_ahead(hpet_t1_cmp, hpet_readl(HPET_COUNTER)));

	if (lost_ints) {
		if (hpet_rtc_flags & RTC_PIE)
			hpet_pie_count += lost_ints;
		if (printk_ratelimit())
			printk(KERN_WARNING "hpet1: lost %d rtc interrupts\n",
				lost_ints);
	}
}

irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
{
	struct rtc_time curr_time;
	unsigned long rtc_int_flag = 0;

	hpet_rtc_timer_reinit();
	memset(&curr_time, 0, sizeof(struct rtc_time));

	if (hpet_rtc_flags & (RTC_UIE | RTC_AIE))
		get_rtc_time(&curr_time);

	if (hpet_rtc_flags & RTC_UIE &&
	    curr_time.tm_sec != hpet_prev_update_sec) {
		if (hpet_prev_update_sec >= 0)
			rtc_int_flag = RTC_UF;
		hpet_prev_update_sec = curr_time.tm_sec;
	}

	if (hpet_rtc_flags & RTC_PIE &&
	    ++hpet_pie_count >= hpet_pie_limit) {
		rtc_int_flag |= RTC_PF;
		hpet_pie_count = 0;
	}

	if (hpet_rtc_flags & RTC_AIE &&
	    (curr_time.tm_sec == hpet_alarm_time.tm_sec) &&
	    (curr_time.tm_min == hpet_alarm_time.tm_min) &&
	    (curr_time.tm_hour == hpet_alarm_time.tm_hour))
			rtc_int_flag |= RTC_AF;

	if (rtc_int_flag) {
		rtc_int_flag |= (RTC_IRQF | (RTC_NUM_INTS << 8));
		if (irq_handler)
			irq_handler(rtc_int_flag, dev_id);
	}
	return IRQ_HANDLED;
}
EXPORT_SYMBOL_GPL(hpet_rtc_interrupt);
#endif