Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

   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
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Common time routines among all ppc machines.
 *
 * Written by Cort Dougan (cort@cs.nmt.edu) to merge
 * Paul Mackerras' version and mine for PReP and Pmac.
 * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
 * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
 *
 * First round of bugfixes by Gabriel Paubert (paubert@iram.es)
 * to make clock more stable (2.4.0-test5). The only thing
 * that this code assumes is that the timebases have been synchronized
 * by firmware on SMP and are never stopped (never do sleep
 * on SMP then, nap and doze are OK).
 * 
 * Speeded up do_gettimeofday by getting rid of references to
 * xtime (which required locks for consistency). (mikejc@us.ibm.com)
 *
 * TODO (not necessarily in this file):
 * - improve precision and reproducibility of timebase frequency
 * measurement at boot time.
 * - for astronomical applications: add a new function to get
 * non ambiguous timestamps even around leap seconds. This needs
 * a new timestamp format and a good name.
 *
 * 1997-09-10  Updated NTP code according to technical memorandum Jan '96
 *             "A Kernel Model for Precision Timekeeping" by Dave Mills
 */

#include <linux/errno.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/kernel_stat.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/cpu.h>
#include <linux/security.h>
#include <linux/percpu.h>
#include <linux/rtc.h>
#include <linux/jiffies.h>
#include <linux/posix-timers.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/irq_work.h>
#include <linux/clk-provider.h>
#include <linux/suspend.h>
#include <linux/sched/cputime.h>
#include <linux/processor.h>
#include <asm/trace.h>

#include <asm/io.h>
#include <asm/nvram.h>
#include <asm/cache.h>
#include <asm/machdep.h>
#include <linux/uaccess.h>
#include <asm/time.h>
#include <asm/prom.h>
#include <asm/irq.h>
#include <asm/div64.h>
#include <asm/smp.h>
#include <asm/vdso_datapage.h>
#include <asm/firmware.h>
#include <asm/asm-prototypes.h>

/* powerpc clocksource/clockevent code */

#include <linux/clockchips.h>
#include <linux/timekeeper_internal.h>

static u64 rtc_read(struct clocksource *);
static struct clocksource clocksource_rtc = {
	.name         = "rtc",
	.rating       = 400,
	.flags        = CLOCK_SOURCE_IS_CONTINUOUS,
	.mask         = CLOCKSOURCE_MASK(64),
	.read         = rtc_read,
};

static u64 timebase_read(struct clocksource *);
static struct clocksource clocksource_timebase = {
	.name         = "timebase",
	.rating       = 400,
	.flags        = CLOCK_SOURCE_IS_CONTINUOUS,
	.mask         = CLOCKSOURCE_MASK(64),
	.read         = timebase_read,
};

#define DECREMENTER_DEFAULT_MAX 0x7FFFFFFF
u64 decrementer_max = DECREMENTER_DEFAULT_MAX;

static int decrementer_set_next_event(unsigned long evt,
				      struct clock_event_device *dev);
static int decrementer_shutdown(struct clock_event_device *evt);

struct clock_event_device decrementer_clockevent = {
	.name			= "decrementer",
	.rating			= 200,
	.irq			= 0,
	.set_next_event		= decrementer_set_next_event,
	.set_state_oneshot_stopped = decrementer_shutdown,
	.set_state_shutdown	= decrementer_shutdown,
	.tick_resume		= decrementer_shutdown,
	.features		= CLOCK_EVT_FEAT_ONESHOT |
				  CLOCK_EVT_FEAT_C3STOP,
};
EXPORT_SYMBOL(decrementer_clockevent);

DEFINE_PER_CPU(u64, decrementers_next_tb);
static DEFINE_PER_CPU(struct clock_event_device, decrementers);

#define XSEC_PER_SEC (1024*1024)

#ifdef CONFIG_PPC64
#define SCALE_XSEC(xsec, max)	(((xsec) * max) / XSEC_PER_SEC)
#else
/* compute ((xsec << 12) * max) >> 32 */
#define SCALE_XSEC(xsec, max)	mulhwu((xsec) << 12, max)
#endif

unsigned long tb_ticks_per_jiffy;
unsigned long tb_ticks_per_usec = 100; /* sane default */
EXPORT_SYMBOL(tb_ticks_per_usec);
unsigned long tb_ticks_per_sec;
EXPORT_SYMBOL(tb_ticks_per_sec);	/* for cputime_t conversions */

DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL_GPL(rtc_lock);

static u64 tb_to_ns_scale __read_mostly;
static unsigned tb_to_ns_shift __read_mostly;
static u64 boot_tb __read_mostly;

extern struct timezone sys_tz;
static long timezone_offset;

unsigned long ppc_proc_freq;
EXPORT_SYMBOL_GPL(ppc_proc_freq);
unsigned long ppc_tb_freq;
EXPORT_SYMBOL_GPL(ppc_tb_freq);

bool tb_invalid;

#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
/*
 * Factor for converting from cputime_t (timebase ticks) to
 * microseconds. This is stored as 0.64 fixed-point binary fraction.
 */
u64 __cputime_usec_factor;
EXPORT_SYMBOL(__cputime_usec_factor);

#ifdef CONFIG_PPC_SPLPAR
void (*dtl_consumer)(struct dtl_entry *, u64);
#endif

static void calc_cputime_factors(void)
{
	struct div_result res;

	div128_by_32(1000000, 0, tb_ticks_per_sec, &res);
	__cputime_usec_factor = res.result_low;
}

/*
 * Read the SPURR on systems that have it, otherwise the PURR,
 * or if that doesn't exist return the timebase value passed in.
 */
static inline unsigned long read_spurr(unsigned long tb)
{
	if (cpu_has_feature(CPU_FTR_SPURR))
		return mfspr(SPRN_SPURR);
	if (cpu_has_feature(CPU_FTR_PURR))
		return mfspr(SPRN_PURR);
	return tb;
}

#ifdef CONFIG_PPC_SPLPAR

/*
 * Scan the dispatch trace log and count up the stolen time.
 * Should be called with interrupts disabled.
 */
static u64 scan_dispatch_log(u64 stop_tb)
{
	u64 i = local_paca->dtl_ridx;
	struct dtl_entry *dtl = local_paca->dtl_curr;
	struct dtl_entry *dtl_end = local_paca->dispatch_log_end;
	struct lppaca *vpa = local_paca->lppaca_ptr;
	u64 tb_delta;
	u64 stolen = 0;
	u64 dtb;

	if (!dtl)
		return 0;

	if (i == be64_to_cpu(vpa->dtl_idx))
		return 0;
	while (i < be64_to_cpu(vpa->dtl_idx)) {
		dtb = be64_to_cpu(dtl->timebase);
		tb_delta = be32_to_cpu(dtl->enqueue_to_dispatch_time) +
			be32_to_cpu(dtl->ready_to_enqueue_time);
		barrier();
		if (i + N_DISPATCH_LOG < be64_to_cpu(vpa->dtl_idx)) {
			/* buffer has overflowed */
			i = be64_to_cpu(vpa->dtl_idx) - N_DISPATCH_LOG;
			dtl = local_paca->dispatch_log + (i % N_DISPATCH_LOG);
			continue;
		}
		if (dtb > stop_tb)
			break;
		if (dtl_consumer)
			dtl_consumer(dtl, i);
		stolen += tb_delta;
		++i;
		++dtl;
		if (dtl == dtl_end)
			dtl = local_paca->dispatch_log;
	}
	local_paca->dtl_ridx = i;
	local_paca->dtl_curr = dtl;
	return stolen;
}

/*
 * Accumulate stolen time by scanning the dispatch trace log.
 * Called on entry from user mode.
 */
void accumulate_stolen_time(void)
{
	u64 sst, ust;
	unsigned long save_irq_soft_mask = irq_soft_mask_return();
	struct cpu_accounting_data *acct = &local_paca->accounting;

	/* We are called early in the exception entry, before
	 * soft/hard_enabled are sync'ed to the expected state
	 * for the exception. We are hard disabled but the PACA
	 * needs to reflect that so various debug stuff doesn't
	 * complain
	 */
	irq_soft_mask_set(IRQS_DISABLED);

	sst = scan_dispatch_log(acct->starttime_user);
	ust = scan_dispatch_log(acct->starttime);
	acct->stime -= sst;
	acct->utime -= ust;
	acct->steal_time += ust + sst;

	irq_soft_mask_set(save_irq_soft_mask);
}

static inline u64 calculate_stolen_time(u64 stop_tb)
{
	if (!firmware_has_feature(FW_FEATURE_SPLPAR))
		return 0;

	if (get_paca()->dtl_ridx != be64_to_cpu(get_lppaca()->dtl_idx))
		return scan_dispatch_log(stop_tb);

	return 0;
}

#else /* CONFIG_PPC_SPLPAR */
static inline u64 calculate_stolen_time(u64 stop_tb)
{
	return 0;
}

#endif /* CONFIG_PPC_SPLPAR */

/*
 * Account time for a transition between system, hard irq
 * or soft irq state.
 */
static unsigned long vtime_delta_scaled(struct cpu_accounting_data *acct,
					unsigned long now, unsigned long stime)
{
	unsigned long stime_scaled = 0;
#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
	unsigned long nowscaled, deltascaled;
	unsigned long utime, utime_scaled;

	nowscaled = read_spurr(now);
	deltascaled = nowscaled - acct->startspurr;
	acct->startspurr = nowscaled;
	utime = acct->utime - acct->utime_sspurr;
	acct->utime_sspurr = acct->utime;

	/*
	 * Because we don't read the SPURR on every kernel entry/exit,
	 * deltascaled includes both user and system SPURR ticks.
	 * Apportion these ticks to system SPURR ticks and user
	 * SPURR ticks in the same ratio as the system time (delta)
	 * and user time (udelta) values obtained from the timebase
	 * over the same interval.  The system ticks get accounted here;
	 * the user ticks get saved up in paca->user_time_scaled to be
	 * used by account_process_tick.
	 */
	stime_scaled = stime;
	utime_scaled = utime;
	if (deltascaled != stime + utime) {
		if (utime) {
			stime_scaled = deltascaled * stime / (stime + utime);
			utime_scaled = deltascaled - stime_scaled;
		} else {
			stime_scaled = deltascaled;
		}
	}
	acct->utime_scaled += utime_scaled;
#endif

	return stime_scaled;
}

static unsigned long vtime_delta(struct task_struct *tsk,
				 unsigned long *stime_scaled,
				 unsigned long *steal_time)
{
	unsigned long now, stime;
	struct cpu_accounting_data *acct = get_accounting(tsk);

	WARN_ON_ONCE(!irqs_disabled());

	now = mftb();
	stime = now - acct->starttime;
	acct->starttime = now;

	*stime_scaled = vtime_delta_scaled(acct, now, stime);

	*steal_time = calculate_stolen_time(now);

	return stime;
}

void vtime_account_system(struct task_struct *tsk)
{
	unsigned long stime, stime_scaled, steal_time;
	struct cpu_accounting_data *acct = get_accounting(tsk);

	stime = vtime_delta(tsk, &stime_scaled, &steal_time);

	stime -= min(stime, steal_time);
	acct->steal_time += steal_time;

	if ((tsk->flags & PF_VCPU) && !irq_count()) {
		acct->gtime += stime;
#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
		acct->utime_scaled += stime_scaled;
#endif
	} else {
		if (hardirq_count())
			acct->hardirq_time += stime;
		else if (in_serving_softirq())
			acct->softirq_time += stime;
		else
			acct->stime += stime;

#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
		acct->stime_scaled += stime_scaled;
#endif
	}
}
EXPORT_SYMBOL_GPL(vtime_account_system);

void vtime_account_idle(struct task_struct *tsk)
{
	unsigned long stime, stime_scaled, steal_time;
	struct cpu_accounting_data *acct = get_accounting(tsk);

	stime = vtime_delta(tsk, &stime_scaled, &steal_time);
	acct->idle_time += stime + steal_time;
}

static void vtime_flush_scaled(struct task_struct *tsk,
			       struct cpu_accounting_data *acct)
{
#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
	if (acct->utime_scaled)
		tsk->utimescaled += cputime_to_nsecs(acct->utime_scaled);
	if (acct->stime_scaled)
		tsk->stimescaled += cputime_to_nsecs(acct->stime_scaled);

	acct->utime_scaled = 0;
	acct->utime_sspurr = 0;
	acct->stime_scaled = 0;
#endif
}

/*
 * Account the whole cputime accumulated in the paca
 * Must be called with interrupts disabled.
 * Assumes that vtime_account_system/idle() has been called
 * recently (i.e. since the last entry from usermode) so that
 * get_paca()->user_time_scaled is up to date.
 */
void vtime_flush(struct task_struct *tsk)
{
	struct cpu_accounting_data *acct = get_accounting(tsk);

	if (acct->utime)
		account_user_time(tsk, cputime_to_nsecs(acct->utime));

	if (acct->gtime)
		account_guest_time(tsk, cputime_to_nsecs(acct->gtime));

	if (IS_ENABLED(CONFIG_PPC_SPLPAR) && acct->steal_time) {
		account_steal_time(cputime_to_nsecs(acct->steal_time));
		acct->steal_time = 0;
	}

	if (acct->idle_time)
		account_idle_time(cputime_to_nsecs(acct->idle_time));

	if (acct->stime)
		account_system_index_time(tsk, cputime_to_nsecs(acct->stime),
					  CPUTIME_SYSTEM);

	if (acct->hardirq_time)
		account_system_index_time(tsk, cputime_to_nsecs(acct->hardirq_time),
					  CPUTIME_IRQ);
	if (acct->softirq_time)
		account_system_index_time(tsk, cputime_to_nsecs(acct->softirq_time),
					  CPUTIME_SOFTIRQ);

	vtime_flush_scaled(tsk, acct);

	acct->utime = 0;
	acct->gtime = 0;
	acct->idle_time = 0;
	acct->stime = 0;
	acct->hardirq_time = 0;
	acct->softirq_time = 0;
}

#else /* ! CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
#define calc_cputime_factors()
#endif

void __delay(unsigned long loops)
{
	unsigned long start;
	int diff;

	spin_begin();
	if (__USE_RTC()) {
		start = get_rtcl();
		do {
			/* the RTCL register wraps at 1000000000 */
			diff = get_rtcl() - start;
			if (diff < 0)
				diff += 1000000000;
			spin_cpu_relax();
		} while (diff < loops);
	} else if (tb_invalid) {
		/*
		 * TB is in error state and isn't ticking anymore.
		 * HMI handler was unable to recover from TB error.
		 * Return immediately, so that kernel won't get stuck here.
		 */
		spin_cpu_relax();
	} else {
		start = get_tbl();
		while (get_tbl() - start < loops)
			spin_cpu_relax();
	}
	spin_end();
}
EXPORT_SYMBOL(__delay);

void udelay(unsigned long usecs)
{
	__delay(tb_ticks_per_usec * usecs);
}
EXPORT_SYMBOL(udelay);

#ifdef CONFIG_SMP
unsigned long profile_pc(struct pt_regs *regs)
{
	unsigned long pc = instruction_pointer(regs);

	if (in_lock_functions(pc))
		return regs->link;

	return pc;
}
EXPORT_SYMBOL(profile_pc);
#endif

#ifdef CONFIG_IRQ_WORK

/*
 * 64-bit uses a byte in the PACA, 32-bit uses a per-cpu variable...
 */
#ifdef CONFIG_PPC64
static inline unsigned long test_irq_work_pending(void)
{
	unsigned long x;

	asm volatile("lbz %0,%1(13)"
		: "=r" (x)
		: "i" (offsetof(struct paca_struct, irq_work_pending)));
	return x;
}

static inline void set_irq_work_pending_flag(void)
{
	asm volatile("stb %0,%1(13)" : :
		"r" (1),
		"i" (offsetof(struct paca_struct, irq_work_pending)));
}

static inline void clear_irq_work_pending(void)
{
	asm volatile("stb %0,%1(13)" : :
		"r" (0),
		"i" (offsetof(struct paca_struct, irq_work_pending)));
}

void arch_irq_work_raise(void)
{
	preempt_disable();
	set_irq_work_pending_flag();
	/*
	 * Non-nmi code running with interrupts disabled will replay
	 * irq_happened before it re-enables interrupts, so setthe
	 * decrementer there instead of causing a hardware exception
	 * which would immediately hit the masked interrupt handler
	 * and have the net effect of setting the decrementer in
	 * irq_happened.
	 *
	 * NMI interrupts can not check this when they return, so the
	 * decrementer hardware exception is raised, which will fire
	 * when interrupts are next enabled.
	 *
	 * BookE does not support this yet, it must audit all NMI
	 * interrupt handlers to ensure they call nmi_enter() so this
	 * check would be correct.
	 */
	if (IS_ENABLED(CONFIG_BOOKE) || !irqs_disabled() || in_nmi()) {
		set_dec(1);
	} else {
		hard_irq_disable();
		local_paca->irq_happened |= PACA_IRQ_DEC;
	}
	preempt_enable();
}

#else /* 32-bit */

DEFINE_PER_CPU(u8, irq_work_pending);

#define set_irq_work_pending_flag()	__this_cpu_write(irq_work_pending, 1)
#define test_irq_work_pending()		__this_cpu_read(irq_work_pending)
#define clear_irq_work_pending()	__this_cpu_write(irq_work_pending, 0)

void arch_irq_work_raise(void)
{
	preempt_disable();
	set_irq_work_pending_flag();
	set_dec(1);
	preempt_enable();
}

#endif /* 32 vs 64 bit */

#else  /* CONFIG_IRQ_WORK */

#define test_irq_work_pending()	0
#define clear_irq_work_pending()

#endif /* CONFIG_IRQ_WORK */

/*
 * timer_interrupt - gets called when the decrementer overflows,
 * with interrupts disabled.
 */
void timer_interrupt(struct pt_regs *regs)
{
	struct clock_event_device *evt = this_cpu_ptr(&decrementers);
	u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
	struct pt_regs *old_regs;
	u64 now;

	/* Some implementations of hotplug will get timer interrupts while
	 * offline, just ignore these and we also need to set
	 * decrementers_next_tb as MAX to make sure __check_irq_replay
	 * don't replay timer interrupt when return, otherwise we'll trap
	 * here infinitely :(
	 */
	if (unlikely(!cpu_online(smp_processor_id()))) {
		*next_tb = ~(u64)0;
		set_dec(decrementer_max);
		return;
	}

	/* Ensure a positive value is written to the decrementer, or else
	 * some CPUs will continue to take decrementer exceptions. When the
	 * PPC_WATCHDOG (decrementer based) is configured, keep this at most
	 * 31 bits, which is about 4 seconds on most systems, which gives
	 * the watchdog a chance of catching timer interrupt hard lockups.
	 */
	if (IS_ENABLED(CONFIG_PPC_WATCHDOG))
		set_dec(0x7fffffff);
	else
		set_dec(decrementer_max);

	/* Conditionally hard-enable interrupts now that the DEC has been
	 * bumped to its maximum value
	 */
	may_hard_irq_enable();


#if defined(CONFIG_PPC32) && defined(CONFIG_PPC_PMAC)
	if (atomic_read(&ppc_n_lost_interrupts) != 0)
		do_IRQ(regs);
#endif

	old_regs = set_irq_regs(regs);
	irq_enter();
	trace_timer_interrupt_entry(regs);

	if (test_irq_work_pending()) {
		clear_irq_work_pending();
		irq_work_run();
	}

	now = get_tb_or_rtc();
	if (now >= *next_tb) {
		*next_tb = ~(u64)0;
		if (evt->event_handler)
			evt->event_handler(evt);
		__this_cpu_inc(irq_stat.timer_irqs_event);
	} else {
		now = *next_tb - now;
		if (now <= decrementer_max)
			set_dec(now);
		/* We may have raced with new irq work */
		if (test_irq_work_pending())
			set_dec(1);
		__this_cpu_inc(irq_stat.timer_irqs_others);
	}

	trace_timer_interrupt_exit(regs);
	irq_exit();
	set_irq_regs(old_regs);
}
EXPORT_SYMBOL(timer_interrupt);

#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
void timer_broadcast_interrupt(void)
{
	u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);

	*next_tb = ~(u64)0;
	tick_receive_broadcast();
	__this_cpu_inc(irq_stat.broadcast_irqs_event);
}
#endif

/*
 * Hypervisor decrementer interrupts shouldn't occur but are sometimes
 * left pending on exit from a KVM guest.  We don't need to do anything
 * to clear them, as they are edge-triggered.
 */
void hdec_interrupt(struct pt_regs *regs)
{
}

#ifdef CONFIG_SUSPEND
static void generic_suspend_disable_irqs(void)
{
	/* Disable the decrementer, so that it doesn't interfere
	 * with suspending.
	 */

	set_dec(decrementer_max);
	local_irq_disable();
	set_dec(decrementer_max);
}

static void generic_suspend_enable_irqs(void)
{
	local_irq_enable();
}

/* Overrides the weak version in kernel/power/main.c */
void arch_suspend_disable_irqs(void)
{
	if (ppc_md.suspend_disable_irqs)
		ppc_md.suspend_disable_irqs();
	generic_suspend_disable_irqs();
}

/* Overrides the weak version in kernel/power/main.c */
void arch_suspend_enable_irqs(void)
{
	generic_suspend_enable_irqs();
	if (ppc_md.suspend_enable_irqs)
		ppc_md.suspend_enable_irqs();
}
#endif

unsigned long long tb_to_ns(unsigned long long ticks)
{
	return mulhdu(ticks, tb_to_ns_scale) << tb_to_ns_shift;
}
EXPORT_SYMBOL_GPL(tb_to_ns);

/*
 * Scheduler clock - returns current time in nanosec units.
 *
 * Note: mulhdu(a, b) (multiply high double unsigned) returns
 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
 * are 64-bit unsigned numbers.
 */
notrace unsigned long long sched_clock(void)
{
	if (__USE_RTC())
		return get_rtc();
	return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
}


#ifdef CONFIG_PPC_PSERIES

/*
 * Running clock - attempts to give a view of time passing for a virtualised
 * kernels.
 * Uses the VTB register if available otherwise a next best guess.
 */
unsigned long long running_clock(void)
{
	/*
	 * Don't read the VTB as a host since KVM does not switch in host
	 * timebase into the VTB when it takes a guest off the CPU, reading the
	 * VTB would result in reading 'last switched out' guest VTB.
	 *
	 * Host kernels are often compiled with CONFIG_PPC_PSERIES checked, it
	 * would be unsafe to rely only on the #ifdef above.
	 */
	if (firmware_has_feature(FW_FEATURE_LPAR) &&
	    cpu_has_feature(CPU_FTR_ARCH_207S))
		return mulhdu(get_vtb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;

	/*
	 * This is a next best approximation without a VTB.
	 * On a host which is running bare metal there should never be any stolen
	 * time and on a host which doesn't do any virtualisation TB *should* equal
	 * VTB so it makes no difference anyway.
	 */
	return local_clock() - kcpustat_this_cpu->cpustat[CPUTIME_STEAL];
}
#endif

static int __init get_freq(char *name, int cells, unsigned long *val)
{
	struct device_node *cpu;
	const __be32 *fp;
	int found = 0;

	/* The cpu node should have timebase and clock frequency properties */
	cpu = of_find_node_by_type(NULL, "cpu");

	if (cpu) {
		fp = of_get_property(cpu, name, NULL);
		if (fp) {
			found = 1;
			*val = of_read_ulong(fp, cells);
		}

		of_node_put(cpu);
	}

	return found;
}

static void start_cpu_decrementer(void)
{
#if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
	unsigned int tcr;

	/* Clear any pending timer interrupts */
	mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);

	tcr = mfspr(SPRN_TCR);
	/*
	 * The watchdog may have already been enabled by u-boot. So leave
	 * TRC[WP] (Watchdog Period) alone.
	 */
	tcr &= TCR_WP_MASK;	/* Clear all bits except for TCR[WP] */
	tcr |= TCR_DIE;		/* Enable decrementer */
	mtspr(SPRN_TCR, tcr);
#endif
}

void __init generic_calibrate_decr(void)
{
	ppc_tb_freq = DEFAULT_TB_FREQ;		/* hardcoded default */

	if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
	    !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {

		printk(KERN_ERR "WARNING: Estimating decrementer frequency "
				"(not found)\n");
	}

	ppc_proc_freq = DEFAULT_PROC_FREQ;	/* hardcoded default */

	if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
	    !get_freq("clock-frequency", 1, &ppc_proc_freq)) {

		printk(KERN_ERR "WARNING: Estimating processor frequency "
				"(not found)\n");
	}
}

int update_persistent_clock64(struct timespec64 now)
{
	struct rtc_time tm;

	if (!ppc_md.set_rtc_time)
		return -ENODEV;

	rtc_time64_to_tm(now.tv_sec + 1 + timezone_offset, &tm);

	return ppc_md.set_rtc_time(&tm);
}

static void __read_persistent_clock(struct timespec64 *ts)
{
	struct rtc_time tm;
	static int first = 1;

	ts->tv_nsec = 0;
	/* XXX this is a litle fragile but will work okay in the short term */
	if (first) {
		first = 0;
		if (ppc_md.time_init)
			timezone_offset = ppc_md.time_init();

		/* get_boot_time() isn't guaranteed to be safe to call late */
		if (ppc_md.get_boot_time) {
			ts->tv_sec = ppc_md.get_boot_time() - timezone_offset;
			return;
		}
	}
	if (!ppc_md.get_rtc_time) {
		ts->tv_sec = 0;
		return;
	}
	ppc_md.get_rtc_time(&tm);

	ts->tv_sec = rtc_tm_to_time64(&tm);
}

void read_persistent_clock64(struct timespec64 *ts)
{
	__read_persistent_clock(ts);

	/* Sanitize it in case real time clock is set below EPOCH */
	if (ts->tv_sec < 0) {
		ts->tv_sec = 0;
		ts->tv_nsec = 0;
	}
		
}

/* clocksource code */
static notrace u64 rtc_read(struct clocksource *cs)
{
	return (u64)get_rtc();
}

static notrace u64 timebase_read(struct clocksource *cs)
{
	return (u64)get_tb();
}


void update_vsyscall(struct timekeeper *tk)
{
	struct timespec xt;
	struct clocksource *clock = tk->tkr_mono.clock;
	u32 mult = tk->tkr_mono.mult;
	u32 shift = tk->tkr_mono.shift;
	u64 cycle_last = tk->tkr_mono.cycle_last;
	u64 new_tb_to_xs, new_stamp_xsec;
	u64 frac_sec;

	if (clock != &clocksource_timebase)
		return;

	xt.tv_sec = tk->xtime_sec;
	xt.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);

	/* Make userspace gettimeofday spin until we're done. */
	++vdso_data->tb_update_count;
	smp_mb();

	/*
	 * This computes ((2^20 / 1e9) * mult) >> shift as a
	 * 0.64 fixed-point fraction.
	 * The computation in the else clause below won't overflow
	 * (as long as the timebase frequency is >= 1.049 MHz)
	 * but loses precision because we lose the low bits of the constant
	 * in the shift.  Note that 19342813113834067 ~= 2^(20+64) / 1e9.
	 * For a shift of 24 the error is about 0.5e-9, or about 0.5ns
	 * over a second.  (Shift values are usually 22, 23 or 24.)
	 * For high frequency clocks such as the 512MHz timebase clock
	 * on POWER[6789], the mult value is small (e.g. 32768000)
	 * and so we can shift the constant by 16 initially
	 * (295147905179 ~= 2^(20+64-16) / 1e9) and then do the
	 * remaining shifts after the multiplication, which gives a
	 * more accurate result (e.g. with mult = 32768000, shift = 24,
	 * the error is only about 1.2e-12, or 0.7ns over 10 minutes).
	 */
	if (mult <= 62500000 && clock->shift >= 16)
		new_tb_to_xs = ((u64) mult * 295147905179ULL) >> (clock->shift - 16);
	else
		new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift);

	/*
	 * Compute the fractional second in units of 2^-32 seconds.
	 * The fractional second is tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift
	 * in nanoseconds, so multiplying that by 2^32 / 1e9 gives
	 * it in units of 2^-32 seconds.
	 * We assume shift <= 32 because clocks_calc_mult_shift()
	 * generates shift values in the range 0 - 32.
	 */
	frac_sec = tk->tkr_mono.xtime_nsec << (32 - shift);
	do_div(frac_sec, NSEC_PER_SEC);

	/*
	 * Work out new stamp_xsec value for any legacy users of systemcfg.
	 * stamp_xsec is in units of 2^-20 seconds.
	 */
	new_stamp_xsec = frac_sec >> 12;
	new_stamp_xsec += tk->xtime_sec * XSEC_PER_SEC;

	/*
	 * tb_update_count is used to allow the userspace gettimeofday code
	 * to assure itself that it sees a consistent view of the tb_to_xs and
	 * stamp_xsec variables.  It reads the tb_update_count, then reads
	 * tb_to_xs and stamp_xsec and then reads tb_update_count again.  If
	 * the two values of tb_update_count match and are even then the
	 * tb_to_xs and stamp_xsec values are consistent.  If not, then it
	 * loops back and reads them again until this criteria is met.
	 */
	vdso_data->tb_orig_stamp = cycle_last;
	vdso_data->stamp_xsec = new_stamp_xsec;
	vdso_data->tb_to_xs = new_tb_to_xs;
	vdso_data->wtom_clock_sec = tk->wall_to_monotonic.tv_sec;
	vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec;
	vdso_data->stamp_xtime = xt;
	vdso_data->stamp_sec_fraction = frac_sec;
	smp_wmb();
	++(vdso_data->tb_update_count);
}

void update_vsyscall_tz(void)
{
	vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
	vdso_data->tz_dsttime = sys_tz.tz_dsttime;
}

static void __init clocksource_init(void)
{
	struct clocksource *clock;

	if (__USE_RTC())
		clock = &clocksource_rtc;
	else
		clock = &clocksource_timebase;

	if (clocksource_register_hz(clock, tb_ticks_per_sec)) {
		printk(KERN_ERR "clocksource: %s is already registered\n",
		       clock->name);
		return;
	}

	printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
	       clock->name, clock->mult, clock->shift);
}

static int decrementer_set_next_event(unsigned long evt,
				      struct clock_event_device *dev)
{
	__this_cpu_write(decrementers_next_tb, get_tb_or_rtc() + evt);
	set_dec(evt);

	/* We may have raced with new irq work */
	if (test_irq_work_pending())
		set_dec(1);

	return 0;
}

static int decrementer_shutdown(struct clock_event_device *dev)
{
	decrementer_set_next_event(decrementer_max, dev);
	return 0;
}

static void register_decrementer_clockevent(int cpu)
{
	struct clock_event_device *dec = &per_cpu(decrementers, cpu);

	*dec = decrementer_clockevent;
	dec->cpumask = cpumask_of(cpu);

	clockevents_config_and_register(dec, ppc_tb_freq, 2, decrementer_max);

	printk_once(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
		    dec->name, dec->mult, dec->shift, cpu);

	/* Set values for KVM, see kvm_emulate_dec() */
	decrementer_clockevent.mult = dec->mult;
	decrementer_clockevent.shift = dec->shift;
}

static void enable_large_decrementer(void)
{
	if (!cpu_has_feature(CPU_FTR_ARCH_300))
		return;

	if (decrementer_max <= DECREMENTER_DEFAULT_MAX)
		return;

	/*
	 * If we're running as the hypervisor we need to enable the LD manually
	 * otherwise firmware should have done it for us.
	 */
	if (cpu_has_feature(CPU_FTR_HVMODE))
		mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) | LPCR_LD);
}

static void __init set_decrementer_max(void)
{
	struct device_node *cpu;
	u32 bits = 32;

	/* Prior to ISAv3 the decrementer is always 32 bit */
	if (!cpu_has_feature(CPU_FTR_ARCH_300))
		return;

	cpu = of_find_node_by_type(NULL, "cpu");

	if (of_property_read_u32(cpu, "ibm,dec-bits", &bits) == 0) {
		if (bits > 64 || bits < 32) {
			pr_warn("time_init: firmware supplied invalid ibm,dec-bits");
			bits = 32;
		}

		/* calculate the signed maximum given this many bits */
		decrementer_max = (1ul << (bits - 1)) - 1;
	}

	of_node_put(cpu);

	pr_info("time_init: %u bit decrementer (max: %llx)\n",
		bits, decrementer_max);
}

static void __init init_decrementer_clockevent(void)
{
	register_decrementer_clockevent(smp_processor_id());
}

void secondary_cpu_time_init(void)
{
	/* Enable and test the large decrementer for this cpu */
	enable_large_decrementer();

	/* Start the decrementer on CPUs that have manual control
	 * such as BookE
	 */
	start_cpu_decrementer();

	/* FIME: Should make unrelatred change to move snapshot_timebase
	 * call here ! */
	register_decrementer_clockevent(smp_processor_id());
}

/* This function is only called on the boot processor */
void __init time_init(void)
{
	struct div_result res;
	u64 scale;
	unsigned shift;

	if (__USE_RTC()) {
		/* 601 processor: dec counts down by 128 every 128ns */
		ppc_tb_freq = 1000000000;
	} else {
		/* Normal PowerPC with timebase register */
		ppc_md.calibrate_decr();
		printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
		       ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
		printk(KERN_DEBUG "time_init: processor frequency   = %lu.%.6lu MHz\n",
		       ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
	}

	tb_ticks_per_jiffy = ppc_tb_freq / HZ;
	tb_ticks_per_sec = ppc_tb_freq;
	tb_ticks_per_usec = ppc_tb_freq / 1000000;
	calc_cputime_factors();

	/*
	 * Compute scale factor for sched_clock.
	 * The calibrate_decr() function has set tb_ticks_per_sec,
	 * which is the timebase frequency.
	 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
	 * the 128-bit result as a 64.64 fixed-point number.
	 * We then shift that number right until it is less than 1.0,
	 * giving us the scale factor and shift count to use in
	 * sched_clock().
	 */
	div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
	scale = res.result_low;
	for (shift = 0; res.result_high != 0; ++shift) {
		scale = (scale >> 1) | (res.result_high << 63);
		res.result_high >>= 1;
	}
	tb_to_ns_scale = scale;
	tb_to_ns_shift = shift;
	/* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
	boot_tb = get_tb_or_rtc();

	/* If platform provided a timezone (pmac), we correct the time */
	if (timezone_offset) {
		sys_tz.tz_minuteswest = -timezone_offset / 60;
		sys_tz.tz_dsttime = 0;
	}

	vdso_data->tb_update_count = 0;
	vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;

	/* initialise and enable the large decrementer (if we have one) */
	set_decrementer_max();
	enable_large_decrementer();

	/* Start the decrementer on CPUs that have manual control
	 * such as BookE
	 */
	start_cpu_decrementer();

	/* Register the clocksource */
	clocksource_init();

	init_decrementer_clockevent();
	tick_setup_hrtimer_broadcast();

#ifdef CONFIG_COMMON_CLK
	of_clk_init(NULL);
#endif
}

/*
 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
 * result.
 */
void div128_by_32(u64 dividend_high, u64 dividend_low,
		  unsigned divisor, struct div_result *dr)
{
	unsigned long a, b, c, d;
	unsigned long w, x, y, z;
	u64 ra, rb, rc;

	a = dividend_high >> 32;
	b = dividend_high & 0xffffffff;
	c = dividend_low >> 32;
	d = dividend_low & 0xffffffff;

	w = a / divisor;
	ra = ((u64)(a - (w * divisor)) << 32) + b;

	rb = ((u64) do_div(ra, divisor) << 32) + c;
	x = ra;

	rc = ((u64) do_div(rb, divisor) << 32) + d;
	y = rb;

	do_div(rc, divisor);
	z = rc;

	dr->result_high = ((u64)w << 32) + x;
	dr->result_low  = ((u64)y << 32) + z;

}

/* We don't need to calibrate delay, we use the CPU timebase for that */
void calibrate_delay(void)
{
	/* Some generic code (such as spinlock debug) use loops_per_jiffy
	 * as the number of __delay(1) in a jiffy, so make it so
	 */
	loops_per_jiffy = tb_ticks_per_jiffy;
}

#if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
{
	ppc_md.get_rtc_time(tm);
	return 0;
}

static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
{
	if (!ppc_md.set_rtc_time)
		return -EOPNOTSUPP;

	if (ppc_md.set_rtc_time(tm) < 0)
		return -EOPNOTSUPP;

	return 0;
}

static const struct rtc_class_ops rtc_generic_ops = {
	.read_time = rtc_generic_get_time,
	.set_time = rtc_generic_set_time,
};

static int __init rtc_init(void)
{
	struct platform_device *pdev;

	if (!ppc_md.get_rtc_time)
		return -ENODEV;

	pdev = platform_device_register_data(NULL, "rtc-generic", -1,
					     &rtc_generic_ops,
					     sizeof(rtc_generic_ops));

	return PTR_ERR_OR_ZERO(pdev);
}

device_initcall(rtc_init);
#endif