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
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
/*
 *	Local APIC handling, local APIC timers
 *
 *	(c) 1999, 2000 Ingo Molnar <mingo@redhat.com>
 *
 *	Fixes
 *	Maciej W. Rozycki	:	Bits for genuine 82489DX APICs;
 *					thanks to Eric Gilmore
 *					and Rolf G. Tews
 *					for testing these extensively.
 *	Maciej W. Rozycki	:	Various updates and fixes.
 *	Mikael Pettersson	:	Power Management for UP-APIC.
 *	Pavel Machek and
 *	Mikael Pettersson	:	PM converted to driver model.
 */

#include <linux/init.h>

#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/bootmem.h>
#include <linux/smp_lock.h>
#include <linux/interrupt.h>
#include <linux/mc146818rtc.h>
#include <linux/kernel_stat.h>
#include <linux/sysdev.h>
#include <linux/cpu.h>
#include <linux/module.h>

#include <asm/atomic.h>
#include <asm/smp.h>
#include <asm/mtrr.h>
#include <asm/mpspec.h>
#include <asm/desc.h>
#include <asm/arch_hooks.h>
#include <asm/hpet.h>
#include <asm/i8253.h>
#include <asm/nmi.h>

#include <mach_apic.h>
#include <mach_apicdef.h>
#include <mach_ipi.h>

#include "io_ports.h"

/*
 * cpu_mask that denotes the CPUs that needs timer interrupt coming in as
 * IPIs in place of local APIC timers
 */
static cpumask_t timer_bcast_ipi;

/*
 * Knob to control our willingness to enable the local APIC.
 */
static int enable_local_apic __initdata = 0; /* -1=force-disable, +1=force-enable */

static inline void lapic_disable(void)
{
	enable_local_apic = -1;
	clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);
}

static inline void lapic_enable(void)
{
	enable_local_apic = 1;
}

/*
 * Debug level
 */
int apic_verbosity;


static void apic_pm_activate(void);

static int modern_apic(void)
{
	unsigned int lvr, version;
	/* AMD systems use old APIC versions, so check the CPU */
	if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
		boot_cpu_data.x86 >= 0xf)
		return 1;
	lvr = apic_read(APIC_LVR);
	version = GET_APIC_VERSION(lvr);
	return version >= 0x14;
}

/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves.
 */
void ack_bad_irq(unsigned int irq)
{
	printk("unexpected IRQ trap at vector %02x\n", irq);
	/*
	 * Currently unexpected vectors happen only on SMP and APIC.
	 * We _must_ ack these because every local APIC has only N
	 * irq slots per priority level, and a 'hanging, unacked' IRQ
	 * holds up an irq slot - in excessive cases (when multiple
	 * unexpected vectors occur) that might lock up the APIC
	 * completely.
	 * But only ack when the APIC is enabled -AK
	 */
	if (cpu_has_apic)
		ack_APIC_irq();
}

void __init apic_intr_init(void)
{
#ifdef CONFIG_SMP
	smp_intr_init();
#endif
	/* self generated IPI for local APIC timer */
	set_intr_gate(LOCAL_TIMER_VECTOR, apic_timer_interrupt);

	/* IPI vectors for APIC spurious and error interrupts */
	set_intr_gate(SPURIOUS_APIC_VECTOR, spurious_interrupt);
	set_intr_gate(ERROR_APIC_VECTOR, error_interrupt);

	/* thermal monitor LVT interrupt */
#ifdef CONFIG_X86_MCE_P4THERMAL
	set_intr_gate(THERMAL_APIC_VECTOR, thermal_interrupt);
#endif
}

/* Using APIC to generate smp_local_timer_interrupt? */
int using_apic_timer __read_mostly = 0;

static int enabled_via_apicbase;

void enable_NMI_through_LVT0 (void * dummy)
{
	unsigned int v, ver;

	ver = apic_read(APIC_LVR);
	ver = GET_APIC_VERSION(ver);
	v = APIC_DM_NMI;			/* unmask and set to NMI */
	if (!APIC_INTEGRATED(ver))		/* 82489DX */
		v |= APIC_LVT_LEVEL_TRIGGER;
	apic_write_around(APIC_LVT0, v);
}

int get_physical_broadcast(void)
{
	if (modern_apic())
		return 0xff;
	else
		return 0xf;
}

int get_maxlvt(void)
{
	unsigned int v, ver, maxlvt;

	v = apic_read(APIC_LVR);
	ver = GET_APIC_VERSION(v);
	/* 82489DXs do not report # of LVT entries. */
	maxlvt = APIC_INTEGRATED(ver) ? GET_APIC_MAXLVT(v) : 2;
	return maxlvt;
}

void clear_local_APIC(void)
{
	int maxlvt;
	unsigned long v;

	maxlvt = get_maxlvt();

	/*
	 * Masking an LVT entry can trigger a local APIC error
	 * if the vector is zero. Mask LVTERR first to prevent this.
	 */
	if (maxlvt >= 3) {
		v = ERROR_APIC_VECTOR; /* any non-zero vector will do */
		apic_write_around(APIC_LVTERR, v | APIC_LVT_MASKED);
	}
	/*
	 * Careful: we have to set masks only first to deassert
	 * any level-triggered sources.
	 */
	v = apic_read(APIC_LVTT);
	apic_write_around(APIC_LVTT, v | APIC_LVT_MASKED);
	v = apic_read(APIC_LVT0);
	apic_write_around(APIC_LVT0, v | APIC_LVT_MASKED);
	v = apic_read(APIC_LVT1);
	apic_write_around(APIC_LVT1, v | APIC_LVT_MASKED);
	if (maxlvt >= 4) {
		v = apic_read(APIC_LVTPC);
		apic_write_around(APIC_LVTPC, v | APIC_LVT_MASKED);
	}

/* lets not touch this if we didn't frob it */
#ifdef CONFIG_X86_MCE_P4THERMAL
	if (maxlvt >= 5) {
		v = apic_read(APIC_LVTTHMR);
		apic_write_around(APIC_LVTTHMR, v | APIC_LVT_MASKED);
	}
#endif
	/*
	 * Clean APIC state for other OSs:
	 */
	apic_write_around(APIC_LVTT, APIC_LVT_MASKED);
	apic_write_around(APIC_LVT0, APIC_LVT_MASKED);
	apic_write_around(APIC_LVT1, APIC_LVT_MASKED);
	if (maxlvt >= 3)
		apic_write_around(APIC_LVTERR, APIC_LVT_MASKED);
	if (maxlvt >= 4)
		apic_write_around(APIC_LVTPC, APIC_LVT_MASKED);

#ifdef CONFIG_X86_MCE_P4THERMAL
	if (maxlvt >= 5)
		apic_write_around(APIC_LVTTHMR, APIC_LVT_MASKED);
#endif
	v = GET_APIC_VERSION(apic_read(APIC_LVR));
	if (APIC_INTEGRATED(v)) {	/* !82489DX */
		if (maxlvt > 3)		/* Due to Pentium errata 3AP and 11AP. */
			apic_write(APIC_ESR, 0);
		apic_read(APIC_ESR);
	}
}

void __init connect_bsp_APIC(void)
{
	if (pic_mode) {
		/*
		 * Do not trust the local APIC being empty at bootup.
		 */
		clear_local_APIC();
		/*
		 * PIC mode, enable APIC mode in the IMCR, i.e.
		 * connect BSP's local APIC to INT and NMI lines.
		 */
		apic_printk(APIC_VERBOSE, "leaving PIC mode, "
				"enabling APIC mode.\n");
		outb(0x70, 0x22);
		outb(0x01, 0x23);
	}
	enable_apic_mode();
}

void disconnect_bsp_APIC(int virt_wire_setup)
{
	if (pic_mode) {
		/*
		 * Put the board back into PIC mode (has an effect
		 * only on certain older boards).  Note that APIC
		 * interrupts, including IPIs, won't work beyond
		 * this point!  The only exception are INIT IPIs.
		 */
		apic_printk(APIC_VERBOSE, "disabling APIC mode, "
				"entering PIC mode.\n");
		outb(0x70, 0x22);
		outb(0x00, 0x23);
	}
	else {
		/* Go back to Virtual Wire compatibility mode */
		unsigned long value;

		/* For the spurious interrupt use vector F, and enable it */
		value = apic_read(APIC_SPIV);
		value &= ~APIC_VECTOR_MASK;
		value |= APIC_SPIV_APIC_ENABLED;
		value |= 0xf;
		apic_write_around(APIC_SPIV, value);

		if (!virt_wire_setup) {
			/* For LVT0 make it edge triggered, active high, external and enabled */
			value = apic_read(APIC_LVT0);
			value &= ~(APIC_MODE_MASK | APIC_SEND_PENDING |
				APIC_INPUT_POLARITY | APIC_LVT_REMOTE_IRR |
				APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED );
			value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
			value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_EXTINT);
			apic_write_around(APIC_LVT0, value);
		}
		else {
			/* Disable LVT0 */
			apic_write_around(APIC_LVT0, APIC_LVT_MASKED);
		}

		/* For LVT1 make it edge triggered, active high, nmi and enabled */
		value = apic_read(APIC_LVT1);
		value &= ~(
			APIC_MODE_MASK | APIC_SEND_PENDING |
			APIC_INPUT_POLARITY | APIC_LVT_REMOTE_IRR |
			APIC_LVT_LEVEL_TRIGGER | APIC_LVT_MASKED);
		value |= APIC_LVT_REMOTE_IRR | APIC_SEND_PENDING;
		value = SET_APIC_DELIVERY_MODE(value, APIC_MODE_NMI);
		apic_write_around(APIC_LVT1, value);
	}
}

void disable_local_APIC(void)
{
	unsigned long value;

	clear_local_APIC();

	/*
	 * Disable APIC (implies clearing of registers
	 * for 82489DX!).
	 */
	value = apic_read(APIC_SPIV);
	value &= ~APIC_SPIV_APIC_ENABLED;
	apic_write_around(APIC_SPIV, value);

	if (enabled_via_apicbase) {
		unsigned int l, h;
		rdmsr(MSR_IA32_APICBASE, l, h);
		l &= ~MSR_IA32_APICBASE_ENABLE;
		wrmsr(MSR_IA32_APICBASE, l, h);
	}
}

/*
 * This is to verify that we're looking at a real local APIC.
 * Check these against your board if the CPUs aren't getting
 * started for no apparent reason.
 */
int __init verify_local_APIC(void)
{
	unsigned int reg0, reg1;

	/*
	 * The version register is read-only in a real APIC.
	 */
	reg0 = apic_read(APIC_LVR);
	apic_printk(APIC_DEBUG, "Getting VERSION: %x\n", reg0);
	apic_write(APIC_LVR, reg0 ^ APIC_LVR_MASK);
	reg1 = apic_read(APIC_LVR);
	apic_printk(APIC_DEBUG, "Getting VERSION: %x\n", reg1);

	/*
	 * The two version reads above should print the same
	 * numbers.  If the second one is different, then we
	 * poke at a non-APIC.
	 */
	if (reg1 != reg0)
		return 0;

	/*
	 * Check if the version looks reasonably.
	 */
	reg1 = GET_APIC_VERSION(reg0);
	if (reg1 == 0x00 || reg1 == 0xff)
		return 0;
	reg1 = get_maxlvt();
	if (reg1 < 0x02 || reg1 == 0xff)
		return 0;

	/*
	 * The ID register is read/write in a real APIC.
	 */
	reg0 = apic_read(APIC_ID);
	apic_printk(APIC_DEBUG, "Getting ID: %x\n", reg0);

	/*
	 * The next two are just to see if we have sane values.
	 * They're only really relevant if we're in Virtual Wire
	 * compatibility mode, but most boxes are anymore.
	 */
	reg0 = apic_read(APIC_LVT0);
	apic_printk(APIC_DEBUG, "Getting LVT0: %x\n", reg0);
	reg1 = apic_read(APIC_LVT1);
	apic_printk(APIC_DEBUG, "Getting LVT1: %x\n", reg1);

	return 1;
}

void __init sync_Arb_IDs(void)
{
	/* Unsupported on P4 - see Intel Dev. Manual Vol. 3, Ch. 8.6.1
	   And not needed on AMD */
	if (modern_apic())
		return;
	/*
	 * Wait for idle.
	 */
	apic_wait_icr_idle();

	apic_printk(APIC_DEBUG, "Synchronizing Arb IDs.\n");
	apic_write_around(APIC_ICR, APIC_DEST_ALLINC | APIC_INT_LEVELTRIG
				| APIC_DM_INIT);
}

extern void __error_in_apic_c (void);

/*
 * An initial setup of the virtual wire mode.
 */
void __init init_bsp_APIC(void)
{
	unsigned long value, ver;

	/*
	 * Don't do the setup now if we have a SMP BIOS as the
	 * through-I/O-APIC virtual wire mode might be active.
	 */
	if (smp_found_config || !cpu_has_apic)
		return;

	value = apic_read(APIC_LVR);
	ver = GET_APIC_VERSION(value);

	/*
	 * Do not trust the local APIC being empty at bootup.
	 */
	clear_local_APIC();

	/*
	 * Enable APIC.
	 */
	value = apic_read(APIC_SPIV);
	value &= ~APIC_VECTOR_MASK;
	value |= APIC_SPIV_APIC_ENABLED;
	
	/* This bit is reserved on P4/Xeon and should be cleared */
	if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) && (boot_cpu_data.x86 == 15))
		value &= ~APIC_SPIV_FOCUS_DISABLED;
	else
		value |= APIC_SPIV_FOCUS_DISABLED;
	value |= SPURIOUS_APIC_VECTOR;
	apic_write_around(APIC_SPIV, value);

	/*
	 * Set up the virtual wire mode.
	 */
	apic_write_around(APIC_LVT0, APIC_DM_EXTINT);
	value = APIC_DM_NMI;
	if (!APIC_INTEGRATED(ver))		/* 82489DX */
		value |= APIC_LVT_LEVEL_TRIGGER;
	apic_write_around(APIC_LVT1, value);
}

void __devinit setup_local_APIC(void)
{
	unsigned long oldvalue, value, ver, maxlvt;
	int i, j;

	/* Pound the ESR really hard over the head with a big hammer - mbligh */
	if (esr_disable) {
		apic_write(APIC_ESR, 0);
		apic_write(APIC_ESR, 0);
		apic_write(APIC_ESR, 0);
		apic_write(APIC_ESR, 0);
	}

	value = apic_read(APIC_LVR);
	ver = GET_APIC_VERSION(value);

	if ((SPURIOUS_APIC_VECTOR & 0x0f) != 0x0f)
		__error_in_apic_c();

	/*
	 * Double-check whether this APIC is really registered.
	 */
	if (!apic_id_registered())
		BUG();

	/*
	 * Intel recommends to set DFR, LDR and TPR before enabling
	 * an APIC.  See e.g. "AP-388 82489DX User's Manual" (Intel
	 * document number 292116).  So here it goes...
	 */
	init_apic_ldr();

	/*
	 * Set Task Priority to 'accept all'. We never change this
	 * later on.
	 */
	value = apic_read(APIC_TASKPRI);
	value &= ~APIC_TPRI_MASK;
	apic_write_around(APIC_TASKPRI, value);

	/*
	 * After a crash, we no longer service the interrupts and a pending
	 * interrupt from previous kernel might still have ISR bit set.
	 *
	 * Most probably by now CPU has serviced that pending interrupt and
	 * it might not have done the ack_APIC_irq() because it thought,
	 * interrupt came from i8259 as ExtInt. LAPIC did not get EOI so it
	 * does not clear the ISR bit and cpu thinks it has already serivced
	 * the interrupt. Hence a vector might get locked. It was noticed
	 * for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
	 */
	for (i = APIC_ISR_NR - 1; i >= 0; i--) {
		value = apic_read(APIC_ISR + i*0x10);
		for (j = 31; j >= 0; j--) {
			if (value & (1<<j))
				ack_APIC_irq();
		}
	}

	/*
	 * Now that we are all set up, enable the APIC
	 */
	value = apic_read(APIC_SPIV);
	value &= ~APIC_VECTOR_MASK;
	/*
	 * Enable APIC
	 */
	value |= APIC_SPIV_APIC_ENABLED;

	/*
	 * Some unknown Intel IO/APIC (or APIC) errata is biting us with
	 * certain networking cards. If high frequency interrupts are
	 * happening on a particular IOAPIC pin, plus the IOAPIC routing
	 * entry is masked/unmasked at a high rate as well then sooner or
	 * later IOAPIC line gets 'stuck', no more interrupts are received
	 * from the device. If focus CPU is disabled then the hang goes
	 * away, oh well :-(
	 *
	 * [ This bug can be reproduced easily with a level-triggered
	 *   PCI Ne2000 networking cards and PII/PIII processors, dual
	 *   BX chipset. ]
	 */
	/*
	 * Actually disabling the focus CPU check just makes the hang less
	 * frequent as it makes the interrupt distributon model be more
	 * like LRU than MRU (the short-term load is more even across CPUs).
	 * See also the comment in end_level_ioapic_irq().  --macro
	 */
#if 1
	/* Enable focus processor (bit==0) */
	value &= ~APIC_SPIV_FOCUS_DISABLED;
#else
	/* Disable focus processor (bit==1) */
	value |= APIC_SPIV_FOCUS_DISABLED;
#endif
	/*
	 * Set spurious IRQ vector
	 */
	value |= SPURIOUS_APIC_VECTOR;
	apic_write_around(APIC_SPIV, value);

	/*
	 * Set up LVT0, LVT1:
	 *
	 * set up through-local-APIC on the BP's LINT0. This is not
	 * strictly necessery in pure symmetric-IO mode, but sometimes
	 * we delegate interrupts to the 8259A.
	 */
	/*
	 * TODO: set up through-local-APIC from through-I/O-APIC? --macro
	 */
	value = apic_read(APIC_LVT0) & APIC_LVT_MASKED;
	if (!smp_processor_id() && (pic_mode || !value)) {
		value = APIC_DM_EXTINT;
		apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n",
				smp_processor_id());
	} else {
		value = APIC_DM_EXTINT | APIC_LVT_MASKED;
		apic_printk(APIC_VERBOSE, "masked ExtINT on CPU#%d\n",
				smp_processor_id());
	}
	apic_write_around(APIC_LVT0, value);

	/*
	 * only the BP should see the LINT1 NMI signal, obviously.
	 */
	if (!smp_processor_id())
		value = APIC_DM_NMI;
	else
		value = APIC_DM_NMI | APIC_LVT_MASKED;
	if (!APIC_INTEGRATED(ver))		/* 82489DX */
		value |= APIC_LVT_LEVEL_TRIGGER;
	apic_write_around(APIC_LVT1, value);

	if (APIC_INTEGRATED(ver) && !esr_disable) {		/* !82489DX */
		maxlvt = get_maxlvt();
		if (maxlvt > 3)		/* Due to the Pentium erratum 3AP. */
			apic_write(APIC_ESR, 0);
		oldvalue = apic_read(APIC_ESR);

		value = ERROR_APIC_VECTOR;      // enables sending errors
		apic_write_around(APIC_LVTERR, value);
		/*
		 * spec says clear errors after enabling vector.
		 */
		if (maxlvt > 3)
			apic_write(APIC_ESR, 0);
		value = apic_read(APIC_ESR);
		if (value != oldvalue)
			apic_printk(APIC_VERBOSE, "ESR value before enabling "
				"vector: 0x%08lx  after: 0x%08lx\n",
				oldvalue, value);
	} else {
		if (esr_disable)	
			/* 
			 * Something untraceble is creating bad interrupts on 
			 * secondary quads ... for the moment, just leave the
			 * ESR disabled - we can't do anything useful with the
			 * errors anyway - mbligh
			 */
			printk("Leaving ESR disabled.\n");
		else 
			printk("No ESR for 82489DX.\n");
	}

	setup_apic_nmi_watchdog(NULL);
	apic_pm_activate();
}

/*
 * If Linux enabled the LAPIC against the BIOS default
 * disable it down before re-entering the BIOS on shutdown.
 * Otherwise the BIOS may get confused and not power-off.
 * Additionally clear all LVT entries before disable_local_APIC
 * for the case where Linux didn't enable the LAPIC.
 */
void lapic_shutdown(void)
{
	unsigned long flags;

	if (!cpu_has_apic)
		return;

	local_irq_save(flags);
	clear_local_APIC();

	if (enabled_via_apicbase)
		disable_local_APIC();

	local_irq_restore(flags);
}

#ifdef CONFIG_PM

static struct {
	int active;
	/* r/w apic fields */
	unsigned int apic_id;
	unsigned int apic_taskpri;
	unsigned int apic_ldr;
	unsigned int apic_dfr;
	unsigned int apic_spiv;
	unsigned int apic_lvtt;
	unsigned int apic_lvtpc;
	unsigned int apic_lvt0;
	unsigned int apic_lvt1;
	unsigned int apic_lvterr;
	unsigned int apic_tmict;
	unsigned int apic_tdcr;
	unsigned int apic_thmr;
} apic_pm_state;

static int lapic_suspend(struct sys_device *dev, pm_message_t state)
{
	unsigned long flags;
	int maxlvt;

	if (!apic_pm_state.active)
		return 0;

	maxlvt = get_maxlvt();

	apic_pm_state.apic_id = apic_read(APIC_ID);
	apic_pm_state.apic_taskpri = apic_read(APIC_TASKPRI);
	apic_pm_state.apic_ldr = apic_read(APIC_LDR);
	apic_pm_state.apic_dfr = apic_read(APIC_DFR);
	apic_pm_state.apic_spiv = apic_read(APIC_SPIV);
	apic_pm_state.apic_lvtt = apic_read(APIC_LVTT);
	if (maxlvt >= 4)
		apic_pm_state.apic_lvtpc = apic_read(APIC_LVTPC);
	apic_pm_state.apic_lvt0 = apic_read(APIC_LVT0);
	apic_pm_state.apic_lvt1 = apic_read(APIC_LVT1);
	apic_pm_state.apic_lvterr = apic_read(APIC_LVTERR);
	apic_pm_state.apic_tmict = apic_read(APIC_TMICT);
	apic_pm_state.apic_tdcr = apic_read(APIC_TDCR);
#ifdef CONFIG_X86_MCE_P4THERMAL
	if (maxlvt >= 5)
		apic_pm_state.apic_thmr = apic_read(APIC_LVTTHMR);
#endif
	
	local_irq_save(flags);
	disable_local_APIC();
	local_irq_restore(flags);
	return 0;
}

static int lapic_resume(struct sys_device *dev)
{
	unsigned int l, h;
	unsigned long flags;
	int maxlvt;

	if (!apic_pm_state.active)
		return 0;

	maxlvt = get_maxlvt();

	local_irq_save(flags);

	/*
	 * Make sure the APICBASE points to the right address
	 *
	 * FIXME! This will be wrong if we ever support suspend on
	 * SMP! We'll need to do this as part of the CPU restore!
	 */
	rdmsr(MSR_IA32_APICBASE, l, h);
	l &= ~MSR_IA32_APICBASE_BASE;
	l |= MSR_IA32_APICBASE_ENABLE | mp_lapic_addr;
	wrmsr(MSR_IA32_APICBASE, l, h);

	apic_write(APIC_LVTERR, ERROR_APIC_VECTOR | APIC_LVT_MASKED);
	apic_write(APIC_ID, apic_pm_state.apic_id);
	apic_write(APIC_DFR, apic_pm_state.apic_dfr);
	apic_write(APIC_LDR, apic_pm_state.apic_ldr);
	apic_write(APIC_TASKPRI, apic_pm_state.apic_taskpri);
	apic_write(APIC_SPIV, apic_pm_state.apic_spiv);
	apic_write(APIC_LVT0, apic_pm_state.apic_lvt0);
	apic_write(APIC_LVT1, apic_pm_state.apic_lvt1);
#ifdef CONFIG_X86_MCE_P4THERMAL
	if (maxlvt >= 5)
		apic_write(APIC_LVTTHMR, apic_pm_state.apic_thmr);
#endif
	if (maxlvt >= 4)
		apic_write(APIC_LVTPC, apic_pm_state.apic_lvtpc);
	apic_write(APIC_LVTT, apic_pm_state.apic_lvtt);
	apic_write(APIC_TDCR, apic_pm_state.apic_tdcr);
	apic_write(APIC_TMICT, apic_pm_state.apic_tmict);
	apic_write(APIC_ESR, 0);
	apic_read(APIC_ESR);
	apic_write(APIC_LVTERR, apic_pm_state.apic_lvterr);
	apic_write(APIC_ESR, 0);
	apic_read(APIC_ESR);
	local_irq_restore(flags);
	return 0;
}

/*
 * This device has no shutdown method - fully functioning local APICs
 * are needed on every CPU up until machine_halt/restart/poweroff.
 */

static struct sysdev_class lapic_sysclass = {
	set_kset_name("lapic"),
	.resume		= lapic_resume,
	.suspend	= lapic_suspend,
};

static struct sys_device device_lapic = {
	.id	= 0,
	.cls	= &lapic_sysclass,
};

static void __devinit apic_pm_activate(void)
{
	apic_pm_state.active = 1;
}

static int __init init_lapic_sysfs(void)
{
	int error;

	if (!cpu_has_apic)
		return 0;
	/* XXX: remove suspend/resume procs if !apic_pm_state.active? */

	error = sysdev_class_register(&lapic_sysclass);
	if (!error)
		error = sysdev_register(&device_lapic);
	return error;
}
device_initcall(init_lapic_sysfs);

#else	/* CONFIG_PM */

static void apic_pm_activate(void) { }

#endif	/* CONFIG_PM */

/*
 * Detect and enable local APICs on non-SMP boards.
 * Original code written by Keir Fraser.
 */

static int __init apic_set_verbosity(char *str)
{
	if (strcmp("debug", str) == 0)
		apic_verbosity = APIC_DEBUG;
	else if (strcmp("verbose", str) == 0)
		apic_verbosity = APIC_VERBOSE;
	return 1;
}

__setup("apic=", apic_set_verbosity);

static int __init detect_init_APIC (void)
{
	u32 h, l, features;

	/* Disabled by kernel option? */
	if (enable_local_apic < 0)
		return -1;

	switch (boot_cpu_data.x86_vendor) {
	case X86_VENDOR_AMD:
		if ((boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model > 1) ||
		    (boot_cpu_data.x86 == 15))	    
			break;
		goto no_apic;
	case X86_VENDOR_INTEL:
		if (boot_cpu_data.x86 == 6 || boot_cpu_data.x86 == 15 ||
		    (boot_cpu_data.x86 == 5 && cpu_has_apic))
			break;
		goto no_apic;
	default:
		goto no_apic;
	}

	if (!cpu_has_apic) {
		/*
		 * Over-ride BIOS and try to enable the local
		 * APIC only if "lapic" specified.
		 */
		if (enable_local_apic <= 0) {
			printk("Local APIC disabled by BIOS -- "
			       "you can enable it with \"lapic\"\n");
			return -1;
		}
		/*
		 * Some BIOSes disable the local APIC in the
		 * APIC_BASE MSR. This can only be done in
		 * software for Intel P6 or later and AMD K7
		 * (Model > 1) or later.
		 */
		rdmsr(MSR_IA32_APICBASE, l, h);
		if (!(l & MSR_IA32_APICBASE_ENABLE)) {
			printk("Local APIC disabled by BIOS -- reenabling.\n");
			l &= ~MSR_IA32_APICBASE_BASE;
			l |= MSR_IA32_APICBASE_ENABLE | APIC_DEFAULT_PHYS_BASE;
			wrmsr(MSR_IA32_APICBASE, l, h);
			enabled_via_apicbase = 1;
		}
	}
	/*
	 * The APIC feature bit should now be enabled
	 * in `cpuid'
	 */
	features = cpuid_edx(1);
	if (!(features & (1 << X86_FEATURE_APIC))) {
		printk("Could not enable APIC!\n");
		return -1;
	}
	set_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);
	mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;

	/* The BIOS may have set up the APIC at some other address */
	rdmsr(MSR_IA32_APICBASE, l, h);
	if (l & MSR_IA32_APICBASE_ENABLE)
		mp_lapic_addr = l & MSR_IA32_APICBASE_BASE;

	if (nmi_watchdog != NMI_NONE)
		nmi_watchdog = NMI_LOCAL_APIC;

	printk("Found and enabled local APIC!\n");

	apic_pm_activate();

	return 0;

no_apic:
	printk("No local APIC present or hardware disabled\n");
	return -1;
}

void __init init_apic_mappings(void)
{
	unsigned long apic_phys;

	/*
	 * If no local APIC can be found then set up a fake all
	 * zeroes page to simulate the local APIC and another
	 * one for the IO-APIC.
	 */
	if (!smp_found_config && detect_init_APIC()) {
		apic_phys = (unsigned long) alloc_bootmem_pages(PAGE_SIZE);
		apic_phys = __pa(apic_phys);
	} else
		apic_phys = mp_lapic_addr;

	set_fixmap_nocache(FIX_APIC_BASE, apic_phys);
	printk(KERN_DEBUG "mapped APIC to %08lx (%08lx)\n", APIC_BASE,
	       apic_phys);

	/*
	 * Fetch the APIC ID of the BSP in case we have a
	 * default configuration (or the MP table is broken).
	 */
	if (boot_cpu_physical_apicid == -1U)
		boot_cpu_physical_apicid = GET_APIC_ID(apic_read(APIC_ID));

#ifdef CONFIG_X86_IO_APIC
	{
		unsigned long ioapic_phys, idx = FIX_IO_APIC_BASE_0;
		int i;

		for (i = 0; i < nr_ioapics; i++) {
			if (smp_found_config) {
				ioapic_phys = mp_ioapics[i].mpc_apicaddr;
				if (!ioapic_phys) {
					printk(KERN_ERR
					       "WARNING: bogus zero IO-APIC "
					       "address found in MPTABLE, "
					       "disabling IO/APIC support!\n");
					smp_found_config = 0;
					skip_ioapic_setup = 1;
					goto fake_ioapic_page;
				}
			} else {
fake_ioapic_page:
				ioapic_phys = (unsigned long)
					      alloc_bootmem_pages(PAGE_SIZE);
				ioapic_phys = __pa(ioapic_phys);
			}
			set_fixmap_nocache(idx, ioapic_phys);
			printk(KERN_DEBUG "mapped IOAPIC to %08lx (%08lx)\n",
			       __fix_to_virt(idx), ioapic_phys);
			idx++;
		}
	}
#endif
}

/*
 * This part sets up the APIC 32 bit clock in LVTT1, with HZ interrupts
 * per second. We assume that the caller has already set up the local
 * APIC.
 *
 * The APIC timer is not exactly sync with the external timer chip, it
 * closely follows bus clocks.
 */

/*
 * The timer chip is already set up at HZ interrupts per second here,
 * but we do not accept timer interrupts yet. We only allow the BP
 * to calibrate.
 */
static unsigned int __devinit get_8254_timer_count(void)
{
	unsigned long flags;

	unsigned int count;

	spin_lock_irqsave(&i8253_lock, flags);

	outb_p(0x00, PIT_MODE);
	count = inb_p(PIT_CH0);
	count |= inb_p(PIT_CH0) << 8;

	spin_unlock_irqrestore(&i8253_lock, flags);

	return count;
}

/* next tick in 8254 can be caught by catching timer wraparound */
static void __devinit wait_8254_wraparound(void)
{
	unsigned int curr_count, prev_count;

	curr_count = get_8254_timer_count();
	do {
		prev_count = curr_count;
		curr_count = get_8254_timer_count();

		/* workaround for broken Mercury/Neptune */
		if (prev_count >= curr_count + 0x100)
			curr_count = get_8254_timer_count();

	} while (prev_count >= curr_count);
}

/*
 * Default initialization for 8254 timers. If we use other timers like HPET,
 * we override this later
 */
void (*wait_timer_tick)(void) __devinitdata = wait_8254_wraparound;

/*
 * This function sets up the local APIC timer, with a timeout of
 * 'clocks' APIC bus clock. During calibration we actually call
 * this function twice on the boot CPU, once with a bogus timeout
 * value, second time for real. The other (noncalibrating) CPUs
 * call this function only once, with the real, calibrated value.
 *
 * We do reads before writes even if unnecessary, to get around the
 * P5 APIC double write bug.
 */

#define APIC_DIVISOR 16

static void __setup_APIC_LVTT(unsigned int clocks)
{
	unsigned int lvtt_value, tmp_value, ver;
	int cpu = smp_processor_id();

	ver = GET_APIC_VERSION(apic_read(APIC_LVR));
	lvtt_value = APIC_LVT_TIMER_PERIODIC | LOCAL_TIMER_VECTOR;
	if (!APIC_INTEGRATED(ver))
		lvtt_value |= SET_APIC_TIMER_BASE(APIC_TIMER_BASE_DIV);

	if (cpu_isset(cpu, timer_bcast_ipi))
		lvtt_value |= APIC_LVT_MASKED;

	apic_write_around(APIC_LVTT, lvtt_value);

	/*
	 * Divide PICLK by 16
	 */
	tmp_value = apic_read(APIC_TDCR);
	apic_write_around(APIC_TDCR, (tmp_value
				& ~(APIC_TDR_DIV_1 | APIC_TDR_DIV_TMBASE))
				| APIC_TDR_DIV_16);

	apic_write_around(APIC_TMICT, clocks/APIC_DIVISOR);
}

static void __devinit setup_APIC_timer(unsigned int clocks)
{
	unsigned long flags;

	local_irq_save(flags);

	/*
	 * Wait for IRQ0's slice:
	 */
	wait_timer_tick();

	__setup_APIC_LVTT(clocks);

	local_irq_restore(flags);
}

/*
 * In this function we calibrate APIC bus clocks to the external
 * timer. Unfortunately we cannot use jiffies and the timer irq
 * to calibrate, since some later bootup code depends on getting
 * the first irq? Ugh.
 *
 * We want to do the calibration only once since we
 * want to have local timer irqs syncron. CPUs connected
 * by the same APIC bus have the very same bus frequency.
 * And we want to have irqs off anyways, no accidental
 * APIC irq that way.
 */

static int __init calibrate_APIC_clock(void)
{
	unsigned long long t1 = 0, t2 = 0;
	long tt1, tt2;
	long result;
	int i;
	const int LOOPS = HZ/10;

	apic_printk(APIC_VERBOSE, "calibrating APIC timer ...\n");

	/*
	 * Put whatever arbitrary (but long enough) timeout
	 * value into the APIC clock, we just want to get the
	 * counter running for calibration.
	 */
	__setup_APIC_LVTT(1000000000);

	/*
	 * The timer chip counts down to zero. Let's wait
	 * for a wraparound to start exact measurement:
	 * (the current tick might have been already half done)
	 */

	wait_timer_tick();

	/*
	 * We wrapped around just now. Let's start:
	 */
	if (cpu_has_tsc)
		rdtscll(t1);
	tt1 = apic_read(APIC_TMCCT);

	/*
	 * Let's wait LOOPS wraprounds:
	 */
	for (i = 0; i < LOOPS; i++)
		wait_timer_tick();

	tt2 = apic_read(APIC_TMCCT);
	if (cpu_has_tsc)
		rdtscll(t2);

	/*
	 * The APIC bus clock counter is 32 bits only, it
	 * might have overflown, but note that we use signed
	 * longs, thus no extra care needed.
	 *
	 * underflown to be exact, as the timer counts down ;)
	 */

	result = (tt1-tt2)*APIC_DIVISOR/LOOPS;

	if (cpu_has_tsc)
		apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
			"%ld.%04ld MHz.\n",
			((long)(t2-t1)/LOOPS)/(1000000/HZ),
			((long)(t2-t1)/LOOPS)%(1000000/HZ));

	apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
		"%ld.%04ld MHz.\n",
		result/(1000000/HZ),
		result%(1000000/HZ));

	return result;
}

static unsigned int calibration_result;

void __init setup_boot_APIC_clock(void)
{
	unsigned long flags;
	apic_printk(APIC_VERBOSE, "Using local APIC timer interrupts.\n");
	using_apic_timer = 1;

	local_irq_save(flags);

	calibration_result = calibrate_APIC_clock();
	/*
	 * Now set up the timer for real.
	 */
	setup_APIC_timer(calibration_result);

	local_irq_restore(flags);
}

void __devinit setup_secondary_APIC_clock(void)
{
	setup_APIC_timer(calibration_result);
}

void disable_APIC_timer(void)
{
	if (using_apic_timer) {
		unsigned long v;

		v = apic_read(APIC_LVTT);
		/*
		 * When an illegal vector value (0-15) is written to an LVT
		 * entry and delivery mode is Fixed, the APIC may signal an
		 * illegal vector error, with out regard to whether the mask
		 * bit is set or whether an interrupt is actually seen on input.
		 *
		 * Boot sequence might call this function when the LVTT has
		 * '0' vector value. So make sure vector field is set to
		 * valid value.
		 */
		v |= (APIC_LVT_MASKED | LOCAL_TIMER_VECTOR);
		apic_write_around(APIC_LVTT, v);
	}
}

void enable_APIC_timer(void)
{
	int cpu = smp_processor_id();

	if (using_apic_timer &&
	    !cpu_isset(cpu, timer_bcast_ipi)) {
		unsigned long v;

		v = apic_read(APIC_LVTT);
		apic_write_around(APIC_LVTT, v & ~APIC_LVT_MASKED);
	}
}

void switch_APIC_timer_to_ipi(void *cpumask)
{
	cpumask_t mask = *(cpumask_t *)cpumask;
	int cpu = smp_processor_id();

	if (cpu_isset(cpu, mask) &&
	    !cpu_isset(cpu, timer_bcast_ipi)) {
		disable_APIC_timer();
		cpu_set(cpu, timer_bcast_ipi);
	}
}
EXPORT_SYMBOL(switch_APIC_timer_to_ipi);

void switch_ipi_to_APIC_timer(void *cpumask)
{
	cpumask_t mask = *(cpumask_t *)cpumask;
	int cpu = smp_processor_id();

	if (cpu_isset(cpu, mask) &&
	    cpu_isset(cpu, timer_bcast_ipi)) {
		cpu_clear(cpu, timer_bcast_ipi);
		enable_APIC_timer();
	}
}
EXPORT_SYMBOL(switch_ipi_to_APIC_timer);

#undef APIC_DIVISOR

/*
 * Local timer interrupt handler. It does both profiling and
 * process statistics/rescheduling.
 *
 * We do profiling in every local tick, statistics/rescheduling
 * happen only every 'profiling multiplier' ticks. The default
 * multiplier is 1 and it can be changed by writing the new multiplier
 * value into /proc/profile.
 */

inline void smp_local_timer_interrupt(void)
{
	profile_tick(CPU_PROFILING);
#ifdef CONFIG_SMP
	update_process_times(user_mode_vm(get_irq_regs()));
#endif

	/*
	 * We take the 'long' return path, and there every subsystem
	 * grabs the apropriate locks (kernel lock/ irq lock).
	 *
	 * we might want to decouple profiling from the 'long path',
	 * and do the profiling totally in assembly.
	 *
	 * Currently this isn't too much of an issue (performance wise),
	 * we can take more than 100K local irqs per second on a 100 MHz P5.
	 */
}

/*
 * Local APIC timer interrupt. This is the most natural way for doing
 * local interrupts, but local timer interrupts can be emulated by
 * broadcast interrupts too. [in case the hw doesn't support APIC timers]
 *
 * [ if a single-CPU system runs an SMP kernel then we call the local
 *   interrupt as well. Thus we cannot inline the local irq ... ]
 */

fastcall void smp_apic_timer_interrupt(struct pt_regs *regs)
{
	struct pt_regs *old_regs = set_irq_regs(regs);
	int cpu = smp_processor_id();

	/*
	 * the NMI deadlock-detector uses this.
	 */
	per_cpu(irq_stat, cpu).apic_timer_irqs++;

	/*
	 * NOTE! We'd better ACK the irq immediately,
	 * because timer handling can be slow.
	 */
	ack_APIC_irq();
	/*
	 * update_process_times() expects us to have done irq_enter().
	 * Besides, if we don't timer interrupts ignore the global
	 * interrupt lock, which is the WrongThing (tm) to do.
	 */
	irq_enter();
	smp_local_timer_interrupt();
	irq_exit();
	set_irq_regs(old_regs);
}

#ifndef CONFIG_SMP
static void up_apic_timer_interrupt_call(void)
{
	int cpu = smp_processor_id();

	/*
	 * the NMI deadlock-detector uses this.
	 */
	per_cpu(irq_stat, cpu).apic_timer_irqs++;

	smp_local_timer_interrupt();
}
#endif

void smp_send_timer_broadcast_ipi(void)
{
	cpumask_t mask;

	cpus_and(mask, cpu_online_map, timer_bcast_ipi);
	if (!cpus_empty(mask)) {
#ifdef CONFIG_SMP
		send_IPI_mask(mask, LOCAL_TIMER_VECTOR);
#else
		/*
		 * We can directly call the apic timer interrupt handler
		 * in UP case. Minus all irq related functions
		 */
		up_apic_timer_interrupt_call();
#endif
	}
}

int setup_profiling_timer(unsigned int multiplier)
{
	return -EINVAL;
}

/*
 * This interrupt should _never_ happen with our APIC/SMP architecture
 */
fastcall void smp_spurious_interrupt(struct pt_regs *regs)
{
	unsigned long v;

	irq_enter();
	/*
	 * Check if this really is a spurious interrupt and ACK it
	 * if it is a vectored one.  Just in case...
	 * Spurious interrupts should not be ACKed.
	 */
	v = apic_read(APIC_ISR + ((SPURIOUS_APIC_VECTOR & ~0x1f) >> 1));
	if (v & (1 << (SPURIOUS_APIC_VECTOR & 0x1f)))
		ack_APIC_irq();

	/* see sw-dev-man vol 3, chapter 7.4.13.5 */
	printk(KERN_INFO "spurious APIC interrupt on CPU#%d, should never happen.\n",
			smp_processor_id());
	irq_exit();
}

/*
 * This interrupt should never happen with our APIC/SMP architecture
 */

fastcall void smp_error_interrupt(struct pt_regs *regs)
{
	unsigned long v, v1;

	irq_enter();
	/* First tickle the hardware, only then report what went on. -- REW */
	v = apic_read(APIC_ESR);
	apic_write(APIC_ESR, 0);
	v1 = apic_read(APIC_ESR);
	ack_APIC_irq();
	atomic_inc(&irq_err_count);

	/* Here is what the APIC error bits mean:
	   0: Send CS error
	   1: Receive CS error
	   2: Send accept error
	   3: Receive accept error
	   4: Reserved
	   5: Send illegal vector
	   6: Received illegal vector
	   7: Illegal register address
	*/
	printk (KERN_DEBUG "APIC error on CPU%d: %02lx(%02lx)\n",
	        smp_processor_id(), v , v1);
	irq_exit();
}

/*
 * This initializes the IO-APIC and APIC hardware if this is
 * a UP kernel.
 */
int __init APIC_init_uniprocessor (void)
{
	if (enable_local_apic < 0)
		clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);

	if (!smp_found_config && !cpu_has_apic)
		return -1;

	/*
	 * Complain if the BIOS pretends there is one.
	 */
	if (!cpu_has_apic && APIC_INTEGRATED(apic_version[boot_cpu_physical_apicid])) {
		printk(KERN_ERR "BIOS bug, local APIC #%d not detected!...\n",
			boot_cpu_physical_apicid);
		clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);
		return -1;
	}

	verify_local_APIC();

	connect_bsp_APIC();

	/*
	 * Hack: In case of kdump, after a crash, kernel might be booting
	 * on a cpu with non-zero lapic id. But boot_cpu_physical_apicid
	 * might be zero if read from MP tables. Get it from LAPIC.
	 */
#ifdef CONFIG_CRASH_DUMP
	boot_cpu_physical_apicid = GET_APIC_ID(apic_read(APIC_ID));
#endif
	phys_cpu_present_map = physid_mask_of_physid(boot_cpu_physical_apicid);

	setup_local_APIC();

#ifdef CONFIG_X86_IO_APIC
	if (smp_found_config)
		if (!skip_ioapic_setup && nr_ioapics)
			setup_IO_APIC();
#endif
	setup_boot_APIC_clock();

	return 0;
}

static int __init parse_lapic(char *arg)
{
	lapic_enable();
	return 0;
}
early_param("lapic", parse_lapic);

static int __init parse_nolapic(char *arg)
{
	lapic_disable();
	return 0;
}
early_param("nolapic", parse_nolapic);