summaryrefslogtreecommitdiffstats
path: root/cpukit/score/src/kern_tc.c
blob: c22ce121a4de765e879d640a3dd26018a28a2b63 (plain) (blame)
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
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
/**
 * @file
 *
 * @ingroup RTEMSScoreTimecounter
 *
 * @brief This source file contains the definition of
 *  ::_Timecounter, ::_Timecounter_Time_second, and ::_Timecounter_Time_uptime
 *  and the implementation of _Timecounter_Set_NTP_update_second(),
 *  _Timecounter_Binuptime(), _Timecounter_Nanouptime(),
 *  _Timecounter_Microuptime(), _Timecounter_Bintime(),
 *  _Timecounter_Nanotime(), _Timecounter_Microtime(),
 *  _Timecounter_Getbinuptime(), _Timecounter_Getnanouptime(),
 *  _Timecounter_Getmicrouptime(), _Timecounter_Getbintime(),
 *  _Timecounter_Getnanotime(), _Timecounter_Getmicrotime(),
 *  _Timecounter_Getboottime(), _Timecounter_Getboottimebin(), and
 *  _Timecounter_Install().
 */

/*-
 * SPDX-License-Identifier: Beerware
 *
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <phk@FreeBSD.ORG> wrote this file.  As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
 * ----------------------------------------------------------------------------
 *
 * Copyright (c) 2011, 2015, 2016 The FreeBSD Foundation
 *
 * Portions of this software were developed by Julien Ridoux at the University
 * of Melbourne under sponsorship from the FreeBSD Foundation.
 *
 * Portions of this software were developed by Konstantin Belousov
 * under sponsorship from the FreeBSD Foundation.
 */

#ifdef __rtems__
#include <sys/lock.h>
#define	_KERNEL
#define	binuptime(_bt) _Timecounter_Binuptime(_bt)
#define	nanouptime(_tsp) _Timecounter_Nanouptime(_tsp)
#define	microuptime(_tvp) _Timecounter_Microuptime(_tvp)
#define	bintime(_bt) _Timecounter_Bintime(_bt)
#define	nanotime(_tsp) _Timecounter_Nanotime(_tsp)
#define	microtime(_tvp) _Timecounter_Microtime(_tvp)
#define	getbinuptime(_bt) _Timecounter_Getbinuptime(_bt)
#define	getnanouptime(_tsp) _Timecounter_Getnanouptime(_tsp)
#define	getmicrouptime(_tvp) _Timecounter_Getmicrouptime(_tvp)
#define	getbintime(_bt) _Timecounter_Getbintime(_bt)
#define	getnanotime(_tsp) _Timecounter_Getnanotime(_tsp)
#define	getmicrotime(_tvp) _Timecounter_Getmicrotime(_tvp)
#define	getboottime(_tvp) _Timecounter_Getboottime(_tvp)
#define	getboottimebin(_bt) _Timecounter_Getboottimebin(_bt)
#define	tc_init _Timecounter_Install
#define	timecounter _Timecounter
#define	time_second _Timecounter_Time_second
#define	time_uptime _Timecounter_Time_uptime
#include <rtems/score/timecounterimpl.h>
#include <rtems/score/atomic.h>
#include <rtems/score/smp.h>
#include <rtems/score/todimpl.h>
#include <rtems/score/watchdogimpl.h>
#include <rtems/rtems/clock.h>
#endif /* __rtems__ */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_ntp.h"
#include "opt_ffclock.h"

#include <sys/param.h>
#ifndef __rtems__
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sbuf.h>
#include <sys/sleepqueue.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/systm.h>
#endif /* __rtems__ */
#include <sys/timeffc.h>
#include <sys/timepps.h>
#include <sys/timetc.h>
#include <sys/timex.h>
#ifndef __rtems__
#include <sys/vdso.h>
#endif /* __rtems__ */
#ifdef __rtems__
#include <limits.h>
#include <string.h>
#include <rtems.h>
ISR_LOCK_DEFINE(, _Timecounter_Lock, "Timecounter")
#define _Timecounter_Release(lock_context) \
  _ISR_lock_Release_and_ISR_enable(&_Timecounter_Lock, lock_context)
#define hz rtems_clock_get_ticks_per_second()
#define printf(...)
#define log(...)

static inline void
atomic_thread_fence_acq(void)
{

	_Atomic_Fence(ATOMIC_ORDER_ACQUIRE);
}

static inline void
atomic_thread_fence_rel(void)
{

	_Atomic_Fence(ATOMIC_ORDER_RELEASE);
}

static inline u_int
atomic_load_int(Atomic_Uint *i)
{

	return (_Atomic_Load_uint(i, ATOMIC_ORDER_RELAXED));
}

static inline u_int
atomic_load_acq_int(Atomic_Uint *i)
{

	return (_Atomic_Load_uint(i, ATOMIC_ORDER_ACQUIRE));
}

static inline void
atomic_store_rel_int(Atomic_Uint *i, u_int val)
{

	_Atomic_Store_uint(i, val, ATOMIC_ORDER_RELEASE);
}

static inline void *
atomic_load_ptr(void *ptr)
{

	return ((void *)_Atomic_Load_uintptr(ptr, ATOMIC_ORDER_RELAXED));
}

static Timecounter_NTP_update_second _Timecounter_NTP_update_second_handler;

void
_Timecounter_Set_NTP_update_second(Timecounter_NTP_update_second handler)
{

	_Timecounter_NTP_update_second_handler = handler;
}

#define	ntp_update_second(a, b) (*ntp_update_second_handler)(a, b)
#endif /* __rtems__ */

/*
 * A large step happens on boot.  This constant detects such steps.
 * It is relatively small so that ntp_update_second gets called enough
 * in the typical 'missed a couple of seconds' case, but doesn't loop
 * forever when the time step is large.
 */
#define LARGE_STEP	200

/*
 * Implement a dummy timecounter which we can use until we get a real one
 * in the air.  This allows the console and other early stuff to use
 * time services.
 */

static uint32_t
dummy_get_timecount(struct timecounter *tc)
{
#ifndef __rtems__
	static uint32_t now;

	return (++now);
#else /* __rtems__ */
	return 0;
#endif /* __rtems__ */
}

static struct timecounter dummy_timecounter = {
#ifndef __rtems__
	dummy_get_timecount, 0, ~0u, 1000000, "dummy", -1000000
#else /* __rtems__ */
	dummy_get_timecount, ~(uint32_t)0, 1000000, "dummy", -1000000
#endif /* __rtems__ */
};

struct timehands {
	/* These fields must be initialized by the driver. */
	struct timecounter	*th_counter;
	int64_t			th_adjustment;
	uint64_t		th_scale;
	uint32_t		th_large_delta;
	uint32_t	 	th_offset_count;
	struct bintime		th_offset;
	struct bintime		th_bintime;
	struct timeval		th_microtime;
	struct timespec		th_nanotime;
	struct bintime		th_boottime;
	/* Fields not to be copied in tc_windup start with th_generation. */
#ifndef __rtems__
	u_int			th_generation;
#else /* __rtems__ */
	Atomic_Uint		th_generation;
#endif /* __rtems__ */
	struct timehands	*th_next;
};

#ifndef __rtems__
static struct timehands ths[16] = {
    [0] =  {
	.th_counter = &dummy_timecounter,
	.th_scale = (uint64_t)-1 / 1000000,
	.th_large_delta = 1000000,
	.th_offset = { .sec = 1 },
	.th_generation = 1,
    },
};

static struct timehands *volatile timehands = &ths[0];
struct timecounter *timecounter = &dummy_timecounter;
static struct timecounter *timecounters = &dummy_timecounter;

/* Mutex to protect the timecounter list. */
static struct mtx tc_lock;

int tc_min_ticktock_freq = 1;
#else /* __rtems__ */
/*
 * In FreeBSD, the timehands count is a tuning option from two to 16.  The
 * tuning option was added since it is inexpensive and some FreeBSD users asked
 * for it to play around.  The default value is two.  One system which did not
 * work with two timehands was a system with one processor and a specific PPS
 * device.
 *
 * For RTEMS, in uniprocessor configurations, just use one timehand since the
 * update is done with interrupt disabled.
 *
 * In SMP configurations, use a fixed set of two timehands until someone
 * reports an issue.
 */
#if defined(RTEMS_SMP)
static struct timehands th0;
static struct timehands th1 = {
	.th_next = &th0
};
#endif
static struct timehands th0 = {
	.th_counter = &dummy_timecounter,
	.th_scale = (uint64_t)-1 / 1000000,
	.th_offset = { .sec = 1 },
	.th_large_delta = 1000000,
	.th_generation = UINT_MAX,
#ifdef __rtems__
	.th_bintime = { .sec = TOD_SECONDS_1970_THROUGH_1988 },
	.th_microtime = { TOD_SECONDS_1970_THROUGH_1988, 0 },
	.th_nanotime = { TOD_SECONDS_1970_THROUGH_1988, 0 },
	.th_boottime = { .sec = TOD_SECONDS_1970_THROUGH_1988 - 1 },
#endif /* __rtems__ */
#if defined(RTEMS_SMP)
	.th_next = &th1
#else
	.th_next = &th0
#endif
};

static struct timehands *volatile timehands = &th0;
struct timecounter *timecounter = &dummy_timecounter;
#endif /* __rtems__ */

#ifndef __rtems__
volatile time_t time_second = 1;
volatile time_t time_uptime = 1;
#else /* __rtems__ */
volatile time_t time_second = TOD_SECONDS_1970_THROUGH_1988;
volatile int32_t time_uptime = 1;
#endif /* __rtems__ */

#ifndef __rtems__
/*
 * The system time is always computed by summing the estimated boot time and the
 * system uptime. The timehands track boot time, but it changes when the system
 * time is set by the user, stepped by ntpd or adjusted when resuming. It
 * is set to new_time - uptime.
 */
static int sysctl_kern_boottime(SYSCTL_HANDLER_ARGS);
SYSCTL_PROC(_kern, KERN_BOOTTIME, boottime,
    CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
    sysctl_kern_boottime, "S,timeval",
    "Estimated system boottime");

SYSCTL_NODE(_kern, OID_AUTO, timecounter, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "");
static SYSCTL_NODE(_kern_timecounter, OID_AUTO, tc,
    CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
    "");

static int timestepwarnings;
SYSCTL_INT(_kern_timecounter, OID_AUTO, stepwarnings, CTLFLAG_RWTUN,
    &timestepwarnings, 0, "Log time steps");

static int timehands_count = 2;
SYSCTL_INT(_kern_timecounter, OID_AUTO, timehands_count,
    CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
    &timehands_count, 0, "Count of timehands in rotation");

struct bintime bt_timethreshold;
struct bintime bt_tickthreshold;
sbintime_t sbt_timethreshold;
sbintime_t sbt_tickthreshold;
struct bintime tc_tick_bt;
sbintime_t tc_tick_sbt;
int tc_precexp;
int tc_timepercentage = TC_DEFAULTPERC;
static int sysctl_kern_timecounter_adjprecision(SYSCTL_HANDLER_ARGS);
SYSCTL_PROC(_kern_timecounter, OID_AUTO, alloweddeviation,
    CTLTYPE_INT | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, 0, 0,
    sysctl_kern_timecounter_adjprecision, "I",
    "Allowed time interval deviation in percents");

volatile int rtc_generation = 1;

static int tc_chosen;	/* Non-zero if a specific tc was chosen via sysctl. */
static char tc_from_tunable[16];
#endif /* __rtems__ */

static void tc_windup(struct bintime *new_boottimebin);
#ifndef __rtems__
static void cpu_tick_calibrate(int);
#else /* __rtems__ */
static void _Timecounter_Windup(struct bintime *new_boottimebin,
    ISR_lock_Context *lock_context);
#endif /* __rtems__ */

void dtrace_getnanotime(struct timespec *tsp);
void dtrace_getnanouptime(struct timespec *tsp);

#ifndef __rtems__
static int
sysctl_kern_boottime(SYSCTL_HANDLER_ARGS)
{
	struct timeval boottime;

	getboottime(&boottime);

/* i386 is the only arch which uses a 32bits time_t */
#ifdef __amd64__
#ifdef SCTL_MASK32
	int tv[2];

	if (req->flags & SCTL_MASK32) {
		tv[0] = boottime.tv_sec;
		tv[1] = boottime.tv_usec;
		return (SYSCTL_OUT(req, tv, sizeof(tv)));
	}
#endif
#endif
	return (SYSCTL_OUT(req, &boottime, sizeof(boottime)));
}

static int
sysctl_kern_timecounter_get(SYSCTL_HANDLER_ARGS)
{
	uint32_t ncount;
	struct timecounter *tc = arg1;

	ncount = tc->tc_get_timecount(tc);
	return (sysctl_handle_int(oidp, &ncount, 0, req));
}

static int
sysctl_kern_timecounter_freq(SYSCTL_HANDLER_ARGS)
{
	uint64_t freq;
	struct timecounter *tc = arg1;

	freq = tc->tc_frequency;
	return (sysctl_handle_64(oidp, &freq, 0, req));
}
#endif /* __rtems__ */

/*
 * Return the difference between the timehands' counter value now and what
 * was when we copied it to the timehands' offset_count.
 */
static __inline uint32_t
tc_delta(struct timehands *th)
{
	struct timecounter *tc;

	tc = th->th_counter;
	return ((tc->tc_get_timecount(tc) - th->th_offset_count) &
	    tc->tc_counter_mask);
}

static __inline void
bintime_add_tc_delta(struct bintime *bt, uint64_t scale,
    uint64_t large_delta, uint64_t delta)
{
	uint64_t x;

	if (__predict_false(delta >= large_delta)) {
		/* Avoid overflow for scale * delta. */
		x = (scale >> 32) * delta;
		bt->sec += x >> 32;
		bintime_addx(bt, x << 32);
		bintime_addx(bt, (scale & 0xffffffff) * delta);
	} else {
		bintime_addx(bt, scale * delta);
	}
}

/*
 * Functions for reading the time.  We have to loop until we are sure that
 * the timehands that we operated on was not updated under our feet.  See
 * the comment in <sys/time.h> for a description of these 12 functions.
 */

static __inline void
bintime_off(struct bintime *bt, u_int off)
{
	struct timehands *th;
	struct bintime *btp;
	uint64_t scale;
#ifndef __rtems__
	u_int delta, gen, large_delta;
#else /* __rtems__ */
	uint32_t delta, large_delta;
	u_int gen;
#endif /* __rtems__ */

	do {
		th = timehands;
		gen = atomic_load_acq_int(&th->th_generation);
		btp = (struct bintime *)((vm_offset_t)th + off);
		*bt = *btp;
		scale = th->th_scale;
		delta = tc_delta(th);
		large_delta = th->th_large_delta;
		atomic_thread_fence_acq();
#if defined(RTEMS_SMP)
	} while (gen == 0 || gen != th->th_generation);
#else
	} while (gen != th->th_generation);
#endif

	bintime_add_tc_delta(bt, scale, large_delta, delta);
}
#define	GETTHBINTIME(dst, member)					\
do {									\
	_Static_assert(_Generic(((struct timehands *)NULL)->member,	\
	    struct bintime: 1, default: 0) == 1,			\
	    "struct timehands member is not of struct bintime type");	\
	bintime_off(dst, __offsetof(struct timehands, member));		\
} while (0)

static __inline void
getthmember(void *out, size_t out_size, u_int off)
{
	struct timehands *th;
	u_int gen;

	do {
		th = timehands;
		gen = atomic_load_acq_int(&th->th_generation);
		memcpy(out, (char *)th + off, out_size);
		atomic_thread_fence_acq();
#if defined(RTEMS_SMP)
	} while (gen == 0 || gen != th->th_generation);
#else
	} while (gen != th->th_generation);
#endif
}
#define	GETTHMEMBER(dst, member)					\
do {									\
	_Static_assert(_Generic(*dst,					\
	    __typeof(((struct timehands *)NULL)->member): 1,		\
	    default: 0) == 1,						\
	    "*dst and struct timehands member have different types");	\
	getthmember(dst, sizeof(*dst), __offsetof(struct timehands,	\
	    member));							\
} while (0)

#ifdef FFCLOCK
void
fbclock_binuptime(struct bintime *bt)
{

	GETTHBINTIME(bt, th_offset);
}

void
fbclock_nanouptime(struct timespec *tsp)
{
	struct bintime bt;

	fbclock_binuptime(&bt);
	bintime2timespec(&bt, tsp);
}

void
fbclock_microuptime(struct timeval *tvp)
{
	struct bintime bt;

	fbclock_binuptime(&bt);
	bintime2timeval(&bt, tvp);
}

void
fbclock_bintime(struct bintime *bt)
{

	GETTHBINTIME(bt, th_bintime);
}

void
fbclock_nanotime(struct timespec *tsp)
{
	struct bintime bt;

	fbclock_bintime(&bt);
	bintime2timespec(&bt, tsp);
}

void
fbclock_microtime(struct timeval *tvp)
{
	struct bintime bt;

	fbclock_bintime(&bt);
	bintime2timeval(&bt, tvp);
}

void
fbclock_getbinuptime(struct bintime *bt)
{

	GETTHMEMBER(bt, th_offset);
}

void
fbclock_getnanouptime(struct timespec *tsp)
{
	struct bintime bt;

	GETTHMEMBER(&bt, th_offset);
	bintime2timespec(&bt, tsp);
}

void
fbclock_getmicrouptime(struct timeval *tvp)
{
	struct bintime bt;

	GETTHMEMBER(&bt, th_offset);
	bintime2timeval(&bt, tvp);
}

void
fbclock_getbintime(struct bintime *bt)
{

	GETTHMEMBER(bt, th_bintime);
}

void
fbclock_getnanotime(struct timespec *tsp)
{

	GETTHMEMBER(tsp, th_nanotime);
}

void
fbclock_getmicrotime(struct timeval *tvp)
{

	GETTHMEMBER(tvp, th_microtime);
}
#else /* !FFCLOCK */

void
binuptime(struct bintime *bt)
{

	GETTHBINTIME(bt, th_offset);
}
#ifdef __rtems__
sbintime_t
_Timecounter_Sbinuptime(void)
{
	struct timehands *th;
	sbintime_t sbt;
	uint64_t scale;
	uint32_t delta;
	uint32_t large_delta;
	u_int gen;

	do {
		th = timehands;
		gen = atomic_load_acq_int(&th->th_generation);
		sbt = bttosbt(th->th_offset);
		scale = th->th_scale;
		delta = tc_delta(th);
		large_delta = th->th_large_delta;
		atomic_thread_fence_acq();
#if defined(RTEMS_SMP)
	} while (gen == 0 || gen != th->th_generation);
#else
	} while (gen != th->th_generation);
#endif

	if (__predict_false(delta >= large_delta)) {
		/* Avoid overflow for scale * delta. */
		sbt += (scale >> 32) * delta;
		sbt += ((scale & 0xffffffff) * delta) >> 32;
	} else {
		sbt += (scale * delta) >> 32;
	}

	return (sbt);
}
#endif /* __rtems__ */

void
nanouptime(struct timespec *tsp)
{
	struct bintime bt;

	binuptime(&bt);
	bintime2timespec(&bt, tsp);
}

void
microuptime(struct timeval *tvp)
{
	struct bintime bt;

	binuptime(&bt);
	bintime2timeval(&bt, tvp);
}

void
bintime(struct bintime *bt)
{

	GETTHBINTIME(bt, th_bintime);
}

void
nanotime(struct timespec *tsp)
{
	struct bintime bt;

	bintime(&bt);
	bintime2timespec(&bt, tsp);
}

void
microtime(struct timeval *tvp)
{
	struct bintime bt;

	bintime(&bt);
	bintime2timeval(&bt, tvp);
}

void
getbinuptime(struct bintime *bt)
{

	GETTHMEMBER(bt, th_offset);
}

void
getnanouptime(struct timespec *tsp)
{
	struct bintime bt;

	GETTHMEMBER(&bt, th_offset);
	bintime2timespec(&bt, tsp);
}

void
getmicrouptime(struct timeval *tvp)
{
	struct bintime bt;

	GETTHMEMBER(&bt, th_offset);
	bintime2timeval(&bt, tvp);
}

void
getbintime(struct bintime *bt)
{

	GETTHMEMBER(bt, th_bintime);
}

void
getnanotime(struct timespec *tsp)
{

	GETTHMEMBER(tsp, th_nanotime);
}

void
getmicrotime(struct timeval *tvp)
{

	GETTHMEMBER(tvp, th_microtime);
}
#endif /* FFCLOCK */

#ifdef __rtems__
void
rtems_clock_get_boot_time(struct timespec *boottime)
{
	struct bintime boottimebin;

	getboottimebin(&boottimebin);
	bintime2timespec(&boottimebin, boottime);
}
#endif /* __rtems__ */
void
getboottime(struct timeval *boottime)
{
	struct bintime boottimebin;

	getboottimebin(&boottimebin);
	bintime2timeval(&boottimebin, boottime);
}

void
getboottimebin(struct bintime *boottimebin)
{

	GETTHMEMBER(boottimebin, th_boottime);
}

#ifdef FFCLOCK
/*
 * Support for feed-forward synchronization algorithms. This is heavily inspired
 * by the timehands mechanism but kept independent from it. *_windup() functions
 * have some connection to avoid accessing the timecounter hardware more than
 * necessary.
 */

/* Feed-forward clock estimates kept updated by the synchronization daemon. */
struct ffclock_estimate ffclock_estimate;
struct bintime ffclock_boottime;	/* Feed-forward boot time estimate. */
uint32_t ffclock_status;		/* Feed-forward clock status. */
int8_t ffclock_updated;			/* New estimates are available. */
struct mtx ffclock_mtx;			/* Mutex on ffclock_estimate. */

struct fftimehands {
	struct ffclock_estimate	cest;
	struct bintime		tick_time;
	struct bintime		tick_time_lerp;
	ffcounter		tick_ffcount;
	uint64_t		period_lerp;
	volatile uint8_t	gen;
	struct fftimehands	*next;
};

#define	NUM_ELEMENTS(x) (sizeof(x) / sizeof(*x))

static struct fftimehands ffth[10];
static struct fftimehands *volatile fftimehands = ffth;

static void
ffclock_init(void)
{
	struct fftimehands *cur;
	struct fftimehands *last;

	memset(ffth, 0, sizeof(ffth));

	last = ffth + NUM_ELEMENTS(ffth) - 1;
	for (cur = ffth; cur < last; cur++)
		cur->next = cur + 1;
	last->next = ffth;

	ffclock_updated = 0;
	ffclock_status = FFCLOCK_STA_UNSYNC;
	mtx_init(&ffclock_mtx, "ffclock lock", NULL, MTX_DEF);
}

/*
 * Reset the feed-forward clock estimates. Called from inittodr() to get things
 * kick started and uses the timecounter nominal frequency as a first period
 * estimate. Note: this function may be called several time just after boot.
 * Note: this is the only function that sets the value of boot time for the
 * monotonic (i.e. uptime) version of the feed-forward clock.
 */
void
ffclock_reset_clock(struct timespec *ts)
{
	struct timecounter *tc;
	struct ffclock_estimate cest;

	tc = timehands->th_counter;
	memset(&cest, 0, sizeof(struct ffclock_estimate));

	timespec2bintime(ts, &ffclock_boottime);
	timespec2bintime(ts, &(cest.update_time));
	ffclock_read_counter(&cest.update_ffcount);
	cest.leapsec_next = 0;
	cest.period = ((1ULL << 63) / tc->tc_frequency) << 1;
	cest.errb_abs = 0;
	cest.errb_rate = 0;
	cest.status = FFCLOCK_STA_UNSYNC;
	cest.leapsec_total = 0;
	cest.leapsec = 0;

	mtx_lock(&ffclock_mtx);
	bcopy(&cest, &ffclock_estimate, sizeof(struct ffclock_estimate));
	ffclock_updated = INT8_MAX;
	mtx_unlock(&ffclock_mtx);

	printf("ffclock reset: %s (%llu Hz), time = %ld.%09lu\n", tc->tc_name,
	    (unsigned long long)tc->tc_frequency, (long)ts->tv_sec,
	    (unsigned long)ts->tv_nsec);
}

/*
 * Sub-routine to convert a time interval measured in RAW counter units to time
 * in seconds stored in bintime format.
 * NOTE: bintime_mul requires u_int, but the value of the ffcounter may be
 * larger than the max value of u_int (on 32 bit architecture). Loop to consume
 * extra cycles.
 */
static void
ffclock_convert_delta(ffcounter ffdelta, uint64_t period, struct bintime *bt)
{
	struct bintime bt2;
	ffcounter delta, delta_max;

	delta_max = (1ULL << (8 * sizeof(unsigned int))) - 1;
	bintime_clear(bt);
	do {
		if (ffdelta > delta_max)
			delta = delta_max;
		else
			delta = ffdelta;
		bt2.sec = 0;
		bt2.frac = period;
		bintime_mul(&bt2, (unsigned int)delta);
		bintime_add(bt, &bt2);
		ffdelta -= delta;
	} while (ffdelta > 0);
}

/*
 * Update the fftimehands.
 * Push the tick ffcount and time(s) forward based on current clock estimate.
 * The conversion from ffcounter to bintime relies on the difference clock
 * principle, whose accuracy relies on computing small time intervals. If a new
 * clock estimate has been passed by the synchronisation daemon, make it
 * current, and compute the linear interpolation for monotonic time if needed.
 */
static void
ffclock_windup(unsigned int delta)
{
	struct ffclock_estimate *cest;
	struct fftimehands *ffth;
	struct bintime bt, gap_lerp;
	ffcounter ffdelta;
	uint64_t frac;
	unsigned int polling;
	uint8_t forward_jump, ogen;

	/*
	 * Pick the next timehand, copy current ffclock estimates and move tick
	 * times and counter forward.
	 */
	forward_jump = 0;
	ffth = fftimehands->next;
	ogen = ffth->gen;
	ffth->gen = 0;
	cest = &ffth->cest;
	bcopy(&fftimehands->cest, cest, sizeof(struct ffclock_estimate));
	ffdelta = (ffcounter)delta;
	ffth->period_lerp = fftimehands->period_lerp;

	ffth->tick_time = fftimehands->tick_time;
	ffclock_convert_delta(ffdelta, cest->period, &bt);
	bintime_add(&ffth->tick_time, &bt);

	ffth->tick_time_lerp = fftimehands->tick_time_lerp;
	ffclock_convert_delta(ffdelta, ffth->period_lerp, &bt);
	bintime_add(&ffth->tick_time_lerp, &bt);

	ffth->tick_ffcount = fftimehands->tick_ffcount + ffdelta;

	/*
	 * Assess the status of the clock, if the last update is too old, it is
	 * likely the synchronisation daemon is dead and the clock is free
	 * running.
	 */
	if (ffclock_updated == 0) {
		ffdelta = ffth->tick_ffcount - cest->update_ffcount;
		ffclock_convert_delta(ffdelta, cest->period, &bt);
		if (bt.sec > 2 * FFCLOCK_SKM_SCALE)
			ffclock_status |= FFCLOCK_STA_UNSYNC;
	}

	/*
	 * If available, grab updated clock estimates and make them current.
	 * Recompute time at this tick using the updated estimates. The clock
	 * estimates passed the feed-forward synchronisation daemon may result
	 * in time conversion that is not monotonically increasing (just after
	 * the update). time_lerp is a particular linear interpolation over the
	 * synchronisation algo polling period that ensures monotonicity for the
	 * clock ids requesting it.
	 */
	if (ffclock_updated > 0) {
		bcopy(&ffclock_estimate, cest, sizeof(struct ffclock_estimate));
		ffdelta = ffth->tick_ffcount - cest->update_ffcount;
		ffth->tick_time = cest->update_time;
		ffclock_convert_delta(ffdelta, cest->period, &bt);
		bintime_add(&ffth->tick_time, &bt);

		/* ffclock_reset sets ffclock_updated to INT8_MAX */
		if (ffclock_updated == INT8_MAX)
			ffth->tick_time_lerp = ffth->tick_time;

		if (bintime_cmp(&ffth->tick_time, &ffth->tick_time_lerp, >))
			forward_jump = 1;
		else
			forward_jump = 0;

		bintime_clear(&gap_lerp);
		if (forward_jump) {
			gap_lerp = ffth->tick_time;
			bintime_sub(&gap_lerp, &ffth->tick_time_lerp);
		} else {
			gap_lerp = ffth->tick_time_lerp;
			bintime_sub(&gap_lerp, &ffth->tick_time);
		}

		/*
		 * The reset from the RTC clock may be far from accurate, and
		 * reducing the gap between real time and interpolated time
		 * could take a very long time if the interpolated clock insists
		 * on strict monotonicity. The clock is reset under very strict
		 * conditions (kernel time is known to be wrong and
		 * synchronization daemon has been restarted recently.
		 * ffclock_boottime absorbs the jump to ensure boot time is
		 * correct and uptime functions stay consistent.
		 */
		if (((ffclock_status & FFCLOCK_STA_UNSYNC) == FFCLOCK_STA_UNSYNC) &&
		    ((cest->status & FFCLOCK_STA_UNSYNC) == 0) &&
		    ((cest->status & FFCLOCK_STA_WARMUP) == FFCLOCK_STA_WARMUP)) {
			if (forward_jump)
				bintime_add(&ffclock_boottime, &gap_lerp);
			else
				bintime_sub(&ffclock_boottime, &gap_lerp);
			ffth->tick_time_lerp = ffth->tick_time;
			bintime_clear(&gap_lerp);
		}

		ffclock_status = cest->status;
		ffth->period_lerp = cest->period;

		/*
		 * Compute corrected period used for the linear interpolation of
		 * time. The rate of linear interpolation is capped to 5000PPM
		 * (5ms/s).
		 */
		if (bintime_isset(&gap_lerp)) {
			ffdelta = cest->update_ffcount;
			ffdelta -= fftimehands->cest.update_ffcount;
			ffclock_convert_delta(ffdelta, cest->period, &bt);
			polling = bt.sec;
			bt.sec = 0;
			bt.frac = 5000000 * (uint64_t)18446744073LL;
			bintime_mul(&bt, polling);
			if (bintime_cmp(&gap_lerp, &bt, >))
				gap_lerp = bt;

			/* Approximate 1 sec by 1-(1/2^64) to ease arithmetic */
			frac = 0;
			if (gap_lerp.sec > 0) {
				frac -= 1;
				frac /= ffdelta / gap_lerp.sec;
			}
			frac += gap_lerp.frac / ffdelta;

			if (forward_jump)
				ffth->period_lerp += frac;
			else
				ffth->period_lerp -= frac;
		}

		ffclock_updated = 0;
	}
	if (++ogen == 0)
		ogen = 1;
	ffth->gen = ogen;
	fftimehands = ffth;
}

/*
 * Adjust the fftimehands when the timecounter is changed. Stating the obvious,
 * the old and new hardware counter cannot be read simultaneously. tc_windup()
 * does read the two counters 'back to back', but a few cycles are effectively
 * lost, and not accumulated in tick_ffcount. This is a fairly radical
 * operation for a feed-forward synchronization daemon, and it is its job to not
 * pushing irrelevant data to the kernel. Because there is no locking here,
 * simply force to ignore pending or next update to give daemon a chance to
 * realize the counter has changed.
 */
static void
ffclock_change_tc(struct timehands *th)
{
	struct fftimehands *ffth;
	struct ffclock_estimate *cest;
	struct timecounter *tc;
	uint8_t ogen;

	tc = th->th_counter;
	ffth = fftimehands->next;
	ogen = ffth->gen;
	ffth->gen = 0;

	cest = &ffth->cest;
	bcopy(&(fftimehands->cest), cest, sizeof(struct ffclock_estimate));
	cest->period = ((1ULL << 63) / tc->tc_frequency ) << 1;
	cest->errb_abs = 0;
	cest->errb_rate = 0;
	cest->status |= FFCLOCK_STA_UNSYNC;

	ffth->tick_ffcount = fftimehands->tick_ffcount;
	ffth->tick_time_lerp = fftimehands->tick_time_lerp;
	ffth->tick_time = fftimehands->tick_time;
	ffth->period_lerp = cest->period;

	/* Do not lock but ignore next update from synchronization daemon. */
	ffclock_updated--;

	if (++ogen == 0)
		ogen = 1;
	ffth->gen = ogen;
	fftimehands = ffth;
}

/*
 * Retrieve feed-forward counter and time of last kernel tick.
 */
void
ffclock_last_tick(ffcounter *ffcount, struct bintime *bt, uint32_t flags)
{
	struct fftimehands *ffth;
	uint8_t gen;

	/*
	 * No locking but check generation has not changed. Also need to make
	 * sure ffdelta is positive, i.e. ffcount > tick_ffcount.
	 */
	do {
		ffth = fftimehands;
		gen = ffth->gen;
		if ((flags & FFCLOCK_LERP) == FFCLOCK_LERP)
			*bt = ffth->tick_time_lerp;
		else
			*bt = ffth->tick_time;
		*ffcount = ffth->tick_ffcount;
	} while (gen == 0 || gen != ffth->gen);
}

/*
 * Absolute clock conversion. Low level function to convert ffcounter to
 * bintime. The ffcounter is converted using the current ffclock period estimate
 * or the "interpolated period" to ensure monotonicity.
 * NOTE: this conversion may have been deferred, and the clock updated since the
 * hardware counter has been read.
 */
void
ffclock_convert_abs(ffcounter ffcount, struct bintime *bt, uint32_t flags)
{
	struct fftimehands *ffth;
	struct bintime bt2;
	ffcounter ffdelta;
	uint8_t gen;

	/*
	 * No locking but check generation has not changed. Also need to make
	 * sure ffdelta is positive, i.e. ffcount > tick_ffcount.
	 */
	do {
		ffth = fftimehands;
		gen = ffth->gen;
		if (ffcount > ffth->tick_ffcount)
			ffdelta = ffcount - ffth->tick_ffcount;
		else
			ffdelta = ffth->tick_ffcount - ffcount;

		if ((flags & FFCLOCK_LERP) == FFCLOCK_LERP) {
			*bt = ffth->tick_time_lerp;
			ffclock_convert_delta(ffdelta, ffth->period_lerp, &bt2);
		} else {
			*bt = ffth->tick_time;
			ffclock_convert_delta(ffdelta, ffth->cest.period, &bt2);
		}

		if (ffcount > ffth->tick_ffcount)
			bintime_add(bt, &bt2);
		else
			bintime_sub(bt, &bt2);
	} while (gen == 0 || gen != ffth->gen);
}

/*
 * Difference clock conversion.
 * Low level function to Convert a time interval measured in RAW counter units
 * into bintime. The difference clock allows measuring small intervals much more
 * reliably than the absolute clock.
 */
void
ffclock_convert_diff(ffcounter ffdelta, struct bintime *bt)
{
	struct fftimehands *ffth;
	uint8_t gen;

	/* No locking but check generation has not changed. */
	do {
		ffth = fftimehands;
		gen = ffth->gen;
		ffclock_convert_delta(ffdelta, ffth->cest.period, bt);
	} while (gen == 0 || gen != ffth->gen);
}

/*
 * Access to current ffcounter value.
 */
void
ffclock_read_counter(ffcounter *ffcount)
{
	struct timehands *th;
	struct fftimehands *ffth;
	unsigned int gen, delta;

	/*
	 * ffclock_windup() called from tc_windup(), safe to rely on
	 * th->th_generation only, for correct delta and ffcounter.
	 */
	do {
		th = timehands;
		gen = atomic_load_acq_int(&th->th_generation);
		ffth = fftimehands;
		delta = tc_delta(th);
		*ffcount = ffth->tick_ffcount;
		atomic_thread_fence_acq();
	} while (gen == 0 || gen != th->th_generation);

	*ffcount += delta;
}

void
binuptime(struct bintime *bt)
{

	binuptime_fromclock(bt, sysclock_active);
}

void
nanouptime(struct timespec *tsp)
{

	nanouptime_fromclock(tsp, sysclock_active);
}

void
microuptime(struct timeval *tvp)
{

	microuptime_fromclock(tvp, sysclock_active);
}

void
bintime(struct bintime *bt)
{

	bintime_fromclock(bt, sysclock_active);
}

void
nanotime(struct timespec *tsp)
{

	nanotime_fromclock(tsp, sysclock_active);
}

void
microtime(struct timeval *tvp)
{

	microtime_fromclock(tvp, sysclock_active);
}

void
getbinuptime(struct bintime *bt)
{

	getbinuptime_fromclock(bt, sysclock_active);
}

void
getnanouptime(struct timespec *tsp)
{

	getnanouptime_fromclock(tsp, sysclock_active);
}

void
getmicrouptime(struct timeval *tvp)
{

	getmicrouptime_fromclock(tvp, sysclock_active);
}

void
getbintime(struct bintime *bt)
{

	getbintime_fromclock(bt, sysclock_active);
}

void
getnanotime(struct timespec *tsp)
{

	getnanotime_fromclock(tsp, sysclock_active);
}

void
getmicrotime(struct timeval *tvp)
{

	getmicrouptime_fromclock(tvp, sysclock_active);
}

#endif /* FFCLOCK */

#ifndef __rtems__
/*
 * This is a clone of getnanotime and used for walltimestamps.
 * The dtrace_ prefix prevents fbt from creating probes for
 * it so walltimestamp can be safely used in all fbt probes.
 */
void
dtrace_getnanotime(struct timespec *tsp)
{

	GETTHMEMBER(tsp, th_nanotime);
}

/*
 * This is a clone of getnanouptime used for time since boot.
 * The dtrace_ prefix prevents fbt from creating probes for
 * it so an uptime that can be safely used in all fbt probes.
 */
void
dtrace_getnanouptime(struct timespec *tsp)
{
	struct bintime bt;

	GETTHMEMBER(&bt, th_offset);
	bintime2timespec(&bt, tsp);
}
#endif /* __rtems__ */

#ifdef FFCLOCK
/*
 * System clock currently providing time to the system. Modifiable via sysctl
 * when the FFCLOCK option is defined.
 */
int sysclock_active = SYSCLOCK_FBCK;
#endif

/* Internal NTP status and error estimates. */
extern int time_status;
extern long time_esterror;

#ifndef __rtems__
/*
 * Take a snapshot of sysclock data which can be used to compare system clocks
 * and generate timestamps after the fact.
 */
void
sysclock_getsnapshot(struct sysclock_snap *clock_snap, int fast)
{
	struct fbclock_info *fbi;
	struct timehands *th;
	struct bintime bt;
	unsigned int delta, gen;
#ifdef FFCLOCK
	ffcounter ffcount;
	struct fftimehands *ffth;
	struct ffclock_info *ffi;
	struct ffclock_estimate cest;

	ffi = &clock_snap->ff_info;
#endif

	fbi = &clock_snap->fb_info;
	delta = 0;

	do {
		th = timehands;
		gen = atomic_load_acq_int(&th->th_generation);
		fbi->th_scale = th->th_scale;
		fbi->tick_time = th->th_offset;
#ifdef FFCLOCK
		ffth = fftimehands;
		ffi->tick_time = ffth->tick_time_lerp;
		ffi->tick_time_lerp = ffth->tick_time_lerp;
		ffi->period = ffth->cest.period;
		ffi->period_lerp = ffth->period_lerp;
		clock_snap->ffcount = ffth->tick_ffcount;
		cest = ffth->cest;
#endif
		if (!fast)
			delta = tc_delta(th);
		atomic_thread_fence_acq();
	} while (gen == 0 || gen != th->th_generation);

	clock_snap->delta = delta;
#ifdef FFCLOCK
	clock_snap->sysclock_active = sysclock_active;
#endif

	/* Record feedback clock status and error. */
	clock_snap->fb_info.status = time_status;
	/* XXX: Very crude estimate of feedback clock error. */
	bt.sec = time_esterror / 1000000;
	bt.frac = ((time_esterror - bt.sec) * 1000000) *
	    (uint64_t)18446744073709ULL;
	clock_snap->fb_info.error = bt;

#ifdef FFCLOCK
	if (!fast)
		clock_snap->ffcount += delta;

	/* Record feed-forward clock leap second adjustment. */
	ffi->leapsec_adjustment = cest.leapsec_total;
	if (clock_snap->ffcount > cest.leapsec_next)
		ffi->leapsec_adjustment -= cest.leapsec;

	/* Record feed-forward clock status and error. */
	clock_snap->ff_info.status = cest.status;
	ffcount = clock_snap->ffcount - cest.update_ffcount;
	ffclock_convert_delta(ffcount, cest.period, &bt);
	/* 18446744073709 = int(2^64/1e12), err_bound_rate in [ps/s]. */
	bintime_mul(&bt, cest.errb_rate * (uint64_t)18446744073709ULL);
	/* 18446744073 = int(2^64 / 1e9), since err_abs in [ns]. */
	bintime_addx(&bt, cest.errb_abs * (uint64_t)18446744073ULL);
	clock_snap->ff_info.error = bt;
#endif
}

/*
 * Convert a sysclock snapshot into a struct bintime based on the specified
 * clock source and flags.
 */
int
sysclock_snap2bintime(struct sysclock_snap *cs, struct bintime *bt,
    int whichclock, uint32_t flags)
{
	struct bintime boottimebin;
#ifdef FFCLOCK
	struct bintime bt2;
	uint64_t period;
#endif

	switch (whichclock) {
	case SYSCLOCK_FBCK:
		*bt = cs->fb_info.tick_time;

		/* If snapshot was created with !fast, delta will be >0. */
		if (cs->delta > 0)
			bintime_addx(bt, cs->fb_info.th_scale * cs->delta);

		if ((flags & FBCLOCK_UPTIME) == 0) {
			getboottimebin(&boottimebin);
			bintime_add(bt, &boottimebin);
		}
		break;
#ifdef FFCLOCK
	case SYSCLOCK_FFWD:
		if (flags & FFCLOCK_LERP) {
			*bt = cs->ff_info.tick_time_lerp;
			period = cs->ff_info.period_lerp;
		} else {
			*bt = cs->ff_info.tick_time;
			period = cs->ff_info.period;
		}

		/* If snapshot was created with !fast, delta will be >0. */
		if (cs->delta > 0) {
			ffclock_convert_delta(cs->delta, period, &bt2);
			bintime_add(bt, &bt2);
		}

		/* Leap second adjustment. */
		if (flags & FFCLOCK_LEAPSEC)
			bt->sec -= cs->ff_info.leapsec_adjustment;

		/* Boot time adjustment, for uptime/monotonic clocks. */
		if (flags & FFCLOCK_UPTIME)
			bintime_sub(bt, &ffclock_boottime);
		break;
#endif
	default:
		return (EINVAL);
		break;
	}

	return (0);
}
#endif /* __rtems__ */

/*
 * Initialize a new timecounter and possibly use it.
 */
void
tc_init(struct timecounter *tc)
{
#ifndef __rtems__
	uint32_t u;
	struct sysctl_oid *tc_root;

	u = tc->tc_frequency / tc->tc_counter_mask;
	/* XXX: We need some margin here, 10% is a guess */
	u *= 11;
	u /= 10;
	if (u > hz && tc->tc_quality >= 0) {
		tc->tc_quality = -2000;
		if (bootverbose) {
			printf("Timecounter \"%s\" frequency %ju Hz",
			    tc->tc_name, (uintmax_t)tc->tc_frequency);
			printf(" -- Insufficient hz, needs at least %u\n", u);
		}
	} else if (tc->tc_quality >= 0 || bootverbose) {
		printf("Timecounter \"%s\" frequency %ju Hz quality %d\n",
		    tc->tc_name, (uintmax_t)tc->tc_frequency,
		    tc->tc_quality);
	}

	/*
	 * Set up sysctl tree for this counter.
	 */
	tc_root = SYSCTL_ADD_NODE_WITH_LABEL(NULL,
	    SYSCTL_STATIC_CHILDREN(_kern_timecounter_tc), OID_AUTO, tc->tc_name,
	    CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
	    "timecounter description", "timecounter");
	SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
	    "mask", CTLFLAG_RD, &(tc->tc_counter_mask), 0,
	    "mask for implemented bits");
	SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
	    "counter", CTLTYPE_UINT | CTLFLAG_RD | CTLFLAG_MPSAFE, tc,
	    sizeof(*tc), sysctl_kern_timecounter_get, "IU",
	    "current timecounter value");
	SYSCTL_ADD_PROC(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
	    "frequency", CTLTYPE_U64 | CTLFLAG_RD | CTLFLAG_MPSAFE, tc,
	    sizeof(*tc), sysctl_kern_timecounter_freq, "QU",
	    "timecounter frequency");
	SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(tc_root), OID_AUTO,
	    "quality", CTLFLAG_RD, &(tc->tc_quality), 0,
	    "goodness of time counter");

	mtx_lock(&tc_lock);
	tc->tc_next = timecounters;
	timecounters = tc;

	/*
	 * Do not automatically switch if the current tc was specifically
	 * chosen.  Never automatically use a timecounter with negative quality.
	 * Even though we run on the dummy counter, switching here may be
	 * worse since this timecounter may not be monotonic.
	 */
	if (tc_chosen)
		goto unlock;
	if (tc->tc_quality < 0)
		goto unlock;
	if (tc_from_tunable[0] != '\0' &&
	    strcmp(tc->tc_name, tc_from_tunable) == 0) {
		tc_chosen = 1;
		tc_from_tunable[0] = '\0';
	} else {
		if (tc->tc_quality < timecounter->tc_quality)
			goto unlock;
		if (tc->tc_quality == timecounter->tc_quality &&
		    tc->tc_frequency < timecounter->tc_frequency)
			goto unlock;
	}
	(void)tc->tc_get_timecount(tc);
	timecounter = tc;
unlock:
	mtx_unlock(&tc_lock);
#else /* __rtems__ */
	if (tc->tc_quality < timecounter->tc_quality)
		return;
	if (tc->tc_quality == timecounter->tc_quality &&
	    tc->tc_frequency < timecounter->tc_frequency)
		return;
	timecounter = tc;
	tc_windup(NULL);
#endif /* __rtems__ */
}

#ifndef __rtems__
/* Report the frequency of the current timecounter. */
uint64_t
tc_getfrequency(void)
{

	return (timehands->th_counter->tc_frequency);
}

static bool
sleeping_on_old_rtc(struct thread *td)
{

	/*
	 * td_rtcgen is modified by curthread when it is running,
	 * and by other threads in this function.  By finding the thread
	 * on a sleepqueue and holding the lock on the sleepqueue
	 * chain, we guarantee that the thread is not running and that
	 * modifying td_rtcgen is safe.  Setting td_rtcgen to zero informs
	 * the thread that it was woken due to a real-time clock adjustment.
	 * (The declaration of td_rtcgen refers to this comment.)
	 */
	if (td->td_rtcgen != 0 && td->td_rtcgen != rtc_generation) {
		td->td_rtcgen = 0;
		return (true);
	}
	return (false);
}

static struct mtx tc_setclock_mtx;
MTX_SYSINIT(tc_setclock_init, &tc_setclock_mtx, "tcsetc", MTX_SPIN);
#endif /* __rtems__ */

/*
 * Step our concept of UTC.  This is done by modifying our estimate of
 * when we booted.
 */
void
#ifndef __rtems__
tc_setclock(struct timespec *ts)
#else /* __rtems__ */
_Timecounter_Set_clock(const struct bintime *_bt,
    ISR_lock_Context *lock_context)
#endif /* __rtems__ */
{
#ifndef __rtems__
	struct timespec tbef, taft;
#endif /* __rtems__ */
	struct bintime bt, bt2;

#ifndef __rtems__
	timespec2bintime(ts, &bt);
	nanotime(&tbef);
	mtx_lock_spin(&tc_setclock_mtx);
	cpu_tick_calibrate(1);
#else /* __rtems__ */
	bt = *_bt;
#endif /* __rtems__ */
	binuptime(&bt2);
	bintime_sub(&bt, &bt2);

	/* XXX fiddle all the little crinkly bits around the fiords... */
#ifndef __rtems__
	tc_windup(&bt);
	mtx_unlock_spin(&tc_setclock_mtx);

	/* Avoid rtc_generation == 0, since td_rtcgen == 0 is special. */
	atomic_add_rel_int(&rtc_generation, 2);
	sleepq_chains_remove_matching(sleeping_on_old_rtc);
	if (timestepwarnings) {
		nanotime(&taft);
		log(LOG_INFO,
		    "Time stepped from %jd.%09ld to %jd.%09ld (%jd.%09ld)\n",
		    (intmax_t)tbef.tv_sec, tbef.tv_nsec,
		    (intmax_t)taft.tv_sec, taft.tv_nsec,
		    (intmax_t)ts->tv_sec, ts->tv_nsec);
	}
#else /* __rtems__ */
	_Timecounter_Windup(&bt, lock_context);
#endif /* __rtems__ */
}

/*
 * Recalculate the scaling factor.  We want the number of 1/2^64
 * fractions of a second per period of the hardware counter, taking
 * into account the th_adjustment factor which the NTP PLL/adjtime(2)
 * processing provides us with.
 *
 * The th_adjustment is nanoseconds per second with 32 bit binary
 * fraction and we want 64 bit binary fraction of second:
 *
 *	 x = a * 2^32 / 10^9 = a * 4.294967296
 *
 * The range of th_adjustment is +/- 5000PPM so inside a 64bit int
 * we can only multiply by about 850 without overflowing, that
 * leaves no suitably precise fractions for multiply before divide.
 *
 * Divide before multiply with a fraction of 2199/512 results in a
 * systematic undercompensation of 10PPM of th_adjustment.  On a
 * 5000PPM adjustment this is a 0.05PPM error.  This is acceptable.
 *
 * We happily sacrifice the lowest of the 64 bits of our result
 * to the goddess of code clarity.
 */
static void
recalculate_scaling_factor_and_large_delta(struct timehands *th)
{
	uint64_t scale;

	scale = (uint64_t)1 << 63;
	scale += (th->th_adjustment / 1024) * 2199;
	scale /= th->th_counter->tc_frequency;
	th->th_scale = scale * 2;
	th->th_large_delta = MIN(((uint64_t)1 << 63) / scale, UINT_MAX);
}

/*
 * Initialize the next struct timehands in the ring and make
 * it the active timehands.  Along the way we might switch to a different
 * timecounter and/or do seconds processing in NTP.  Slightly magic.
 */
static void
tc_windup(struct bintime *new_boottimebin)
#ifdef __rtems__
{
        ISR_lock_Context lock_context;

        _Timecounter_Acquire(&lock_context);
        _Timecounter_Windup(new_boottimebin, &lock_context);
}

static void
_Timecounter_Windup(struct bintime *new_boottimebin,
    ISR_lock_Context *lock_context)
#endif /* __rtems__ */
{
	struct bintime bt;
	struct timecounter *tc;
	struct timehands *th, *tho;
	uint32_t delta, ncount;
#if defined(RTEMS_SMP)
	u_int ogen;
#endif
	int i;
	time_t t;
#ifdef __rtems__
	Timecounter_NTP_update_second ntp_update_second_handler;
#endif

	/*
	 * Make the next timehands a copy of the current one, but do
	 * not overwrite the generation or next pointer.  While we
	 * update the contents, the generation must be zero.  We need
	 * to ensure that the zero generation is visible before the
	 * data updates become visible, which requires release fence.
	 * For similar reasons, re-reading of the generation after the
	 * data is read should use acquire fence.
	 */
	tho = timehands;
#if defined(RTEMS_SMP)
	th = tho->th_next;
	ogen = th->th_generation;
	th->th_generation = 0;
	atomic_thread_fence_rel();
	memcpy(th, tho, offsetof(struct timehands, th_generation));
#else
	th = tho;
#endif
	if (new_boottimebin != NULL)
		th->th_boottime = *new_boottimebin;

	/*
	 * Capture a timecounter delta on the current timecounter and if
	 * changing timecounters, a counter value from the new timecounter.
	 * Update the offset fields accordingly.
	 */
	tc = atomic_load_ptr(&timecounter);
	delta = tc_delta(th);
	if (th->th_counter != tc)
		ncount = tc->tc_get_timecount(tc);
	else
		ncount = 0;
#ifdef FFCLOCK
	ffclock_windup(delta);
#endif
	th->th_offset_count += delta;
	th->th_offset_count &= th->th_counter->tc_counter_mask;
	bintime_add_tc_delta(&th->th_offset, th->th_scale,
	    th->th_large_delta, delta);

#ifndef __rtems__
	/*
	 * Hardware latching timecounters may not generate interrupts on
	 * PPS events, so instead we poll them.  There is a finite risk that
	 * the hardware might capture a count which is later than the one we
	 * got above, and therefore possibly in the next NTP second which might
	 * have a different rate than the current NTP second.  It doesn't
	 * matter in practice.
	 */
	if (tho->th_counter->tc_poll_pps)
		tho->th_counter->tc_poll_pps(tho->th_counter);
#endif /* __rtems__ */

	/*
	 * Deal with NTP second processing.  The loop normally
	 * iterates at most once, but in extreme situations it might
	 * keep NTP sane if timeouts are not run for several seconds.
	 * At boot, the time step can be large when the TOD hardware
	 * has been read, so on really large steps, we call
	 * ntp_update_second only twice.  We need to call it twice in
	 * case we missed a leap second.
	 */
	bt = th->th_offset;
	bintime_add(&bt, &th->th_boottime);
#ifdef __rtems__
	ntp_update_second_handler = _Timecounter_NTP_update_second_handler;
	if (ntp_update_second_handler != NULL) {
#endif /* __rtems__ */
	i = bt.sec - tho->th_microtime.tv_sec;
	if (i > 0) {
		if (i > LARGE_STEP)
			i = 2;

		do {
			t = bt.sec;
			ntp_update_second(&th->th_adjustment, &bt.sec);
			if (bt.sec != t)
				th->th_boottime.sec += bt.sec - t;
			--i;
		} while (i > 0);

		recalculate_scaling_factor_and_large_delta(th);
	}
#ifdef __rtems__
	}
#endif /* __rtems__ */

	/* Update the UTC timestamps used by the get*() functions. */
	th->th_bintime = bt;
	bintime2timeval(&bt, &th->th_microtime);
	bintime2timespec(&bt, &th->th_nanotime);

	/* Now is a good time to change timecounters. */
	if (th->th_counter != tc) {
#ifndef __rtems__
#ifndef __arm__
		if ((tc->tc_flags & TC_FLAGS_C2STOP) != 0)
			cpu_disable_c2_sleep++;
		if ((th->th_counter->tc_flags & TC_FLAGS_C2STOP) != 0)
			cpu_disable_c2_sleep--;
#endif
#endif /* __rtems__ */
		th->th_counter = tc;
		th->th_offset_count = ncount;
#ifndef __rtems__
		tc_min_ticktock_freq = max(1, tc->tc_frequency /
		    (((uint64_t)tc->tc_counter_mask + 1) / 3));
#endif /* __rtems__ */
		recalculate_scaling_factor_and_large_delta(th);
#ifdef FFCLOCK
		ffclock_change_tc(th);
#endif
	}

#if defined(RTEMS_SMP)
	/*
	 * Now that the struct timehands is again consistent, set the new
	 * generation number, making sure to not make it zero.
	 */
	if (++ogen == 0)
		ogen = 1;
	atomic_store_rel_int(&th->th_generation, ogen);
#else
	atomic_store_rel_int(&th->th_generation, th->th_generation + 1);
#endif

	/* Go live with the new struct timehands. */
#ifdef FFCLOCK
	switch (sysclock_active) {
	case SYSCLOCK_FBCK:
#endif
		time_second = th->th_microtime.tv_sec;
		time_uptime = th->th_offset.sec;
#ifdef FFCLOCK
		break;
	case SYSCLOCK_FFWD:
		time_second = fftimehands->tick_time_lerp.sec;
		time_uptime = fftimehands->tick_time_lerp.sec - ffclock_boottime.sec;
		break;
	}
#endif

#if defined(RTEMS_SMP)
	timehands = th;
#endif
#ifndef __rtems__
	timekeep_push_vdso();
#endif /* __rtems__ */
#ifdef __rtems__
	_Timecounter_Release(lock_context);
#endif /* __rtems__ */
}

#ifndef __rtems__
/* Report or change the active timecounter hardware. */
static int
sysctl_kern_timecounter_hardware(SYSCTL_HANDLER_ARGS)
{
	char newname[32];
	struct timecounter *newtc, *tc;
	int error;

	mtx_lock(&tc_lock);
	tc = timecounter;
	strlcpy(newname, tc->tc_name, sizeof(newname));
	mtx_unlock(&tc_lock);

	error = sysctl_handle_string(oidp, &newname[0], sizeof(newname), req);
	if (error != 0 || req->newptr == NULL)
		return (error);

	mtx_lock(&tc_lock);
	/* Record that the tc in use now was specifically chosen. */
	tc_chosen = 1;
	if (strcmp(newname, tc->tc_name) == 0) {
		mtx_unlock(&tc_lock);
		return (0);
	}
	for (newtc = timecounters; newtc != NULL; newtc = newtc->tc_next) {
		if (strcmp(newname, newtc->tc_name) != 0)
			continue;

		/* Warm up new timecounter. */
		(void)newtc->tc_get_timecount(newtc);

		timecounter = newtc;

		/*
		 * The vdso timehands update is deferred until the next
		 * 'tc_windup()'.
		 *
		 * This is prudent given that 'timekeep_push_vdso()' does not
		 * use any locking and that it can be called in hard interrupt
		 * context via 'tc_windup()'.
		 */
		break;
	}
	mtx_unlock(&tc_lock);
	return (newtc != NULL ? 0 : EINVAL);
}
SYSCTL_PROC(_kern_timecounter, OID_AUTO, hardware,
    CTLTYPE_STRING | CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, 0, 0,
    sysctl_kern_timecounter_hardware, "A",
    "Timecounter hardware selected");

/* Report the available timecounter hardware. */
static int
sysctl_kern_timecounter_choice(SYSCTL_HANDLER_ARGS)
{
	struct sbuf sb;
	struct timecounter *tc;
	int error;

	error = sysctl_wire_old_buffer(req, 0);
	if (error != 0)
		return (error);
	sbuf_new_for_sysctl(&sb, NULL, 0, req);
	mtx_lock(&tc_lock);
	for (tc = timecounters; tc != NULL; tc = tc->tc_next) {
		if (tc != timecounters)
			sbuf_putc(&sb, ' ');
		sbuf_printf(&sb, "%s(%d)", tc->tc_name, tc->tc_quality);
	}
	mtx_unlock(&tc_lock);
	error = sbuf_finish(&sb);
	sbuf_delete(&sb);
	return (error);
}

SYSCTL_PROC(_kern_timecounter, OID_AUTO, choice,
    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, 0, 0,
    sysctl_kern_timecounter_choice, "A",
    "Timecounter hardware detected");
#endif /* __rtems__ */

#ifndef __rtems__
/*
 * RFC 2783 PPS-API implementation.
 */

/*
 *  Return true if the driver is aware of the abi version extensions in the
 *  pps_state structure, and it supports at least the given abi version number.
 */
static inline int
abi_aware(struct pps_state *pps, int vers)
{

	return ((pps->kcmode & KCMODE_ABIFLAG) && pps->driver_abi >= vers);
}

static int
pps_fetch(struct pps_fetch_args *fapi, struct pps_state *pps)
{
#ifndef __rtems__
	int err, timo;
#else /* __rtems__ */
	int err;
#endif /* __rtems__ */
	pps_seq_t aseq, cseq;
#ifndef __rtems__
	struct timeval tv;
#endif /* __rtems__ */

	if (fapi->tsformat && fapi->tsformat != PPS_TSFMT_TSPEC)
		return (EINVAL);

	/*
	 * If no timeout is requested, immediately return whatever values were
	 * most recently captured.  If timeout seconds is -1, that's a request
	 * to block without a timeout.  WITNESS won't let us sleep forever
	 * without a lock (we really don't need a lock), so just repeatedly
	 * sleep a long time.
	 */
	if (fapi->timeout.tv_sec || fapi->timeout.tv_nsec) {
#ifndef __rtems__
		if (fapi->timeout.tv_sec == -1)
			timo = 0x7fffffff;
		else {
			tv.tv_sec = fapi->timeout.tv_sec;
			tv.tv_usec = fapi->timeout.tv_nsec / 1000;
			timo = tvtohz(&tv);
		}
#endif /* __rtems__ */
		aseq = atomic_load_int(&pps->ppsinfo.assert_sequence);
		cseq = atomic_load_int(&pps->ppsinfo.clear_sequence);
		while (aseq == atomic_load_int(&pps->ppsinfo.assert_sequence) &&
		    cseq == atomic_load_int(&pps->ppsinfo.clear_sequence)) {
#ifndef __rtems__
			if (abi_aware(pps, 1) && pps->driver_mtx != NULL) {
				if (pps->flags & PPSFLAG_MTX_SPIN) {
					err = msleep_spin(pps, pps->driver_mtx,
					    "ppsfch", timo);
				} else {
					err = msleep(pps, pps->driver_mtx, PCATCH,
					    "ppsfch", timo);
				}
			} else {
				err = tsleep(pps, PCATCH, "ppsfch", timo);
			}
			if (err == EWOULDBLOCK) {
				if (fapi->timeout.tv_sec == -1) {
					continue;
				} else {
					return (ETIMEDOUT);
				}
			} else if (err != 0) {
				return (err);
			}
#else /* __rtems__ */
			_Assert(pps->wait != NULL);
			err = (*pps->wait)(pps, fapi->timeout);
			return (err);
#endif /* __rtems__ */
		}
	}

	pps->ppsinfo.current_mode = pps->ppsparam.mode;
	fapi->pps_info_buf = pps->ppsinfo;

	return (0);
}

int
pps_ioctl(u_long cmd, caddr_t data, struct pps_state *pps)
{
	pps_params_t *app;
	struct pps_fetch_args *fapi;
#ifdef FFCLOCK
	struct pps_fetch_ffc_args *fapi_ffc;
#endif
#ifdef PPS_SYNC
	struct pps_kcbind_args *kapi;
#endif

	KASSERT(pps != NULL, ("NULL pps pointer in pps_ioctl"));
	switch (cmd) {
	case PPS_IOC_CREATE:
		return (0);
	case PPS_IOC_DESTROY:
		return (0);
	case PPS_IOC_SETPARAMS:
		app = (pps_params_t *)data;
		if (app->mode & ~pps->ppscap)
			return (EINVAL);
#ifdef FFCLOCK
		/* Ensure only a single clock is selected for ffc timestamp. */
		if ((app->mode & PPS_TSCLK_MASK) == PPS_TSCLK_MASK)
			return (EINVAL);
#endif
		pps->ppsparam = *app;
		return (0);
	case PPS_IOC_GETPARAMS:
		app = (pps_params_t *)data;
		*app = pps->ppsparam;
		app->api_version = PPS_API_VERS_1;
		return (0);
	case PPS_IOC_GETCAP:
		*(int*)data = pps->ppscap;
		return (0);
	case PPS_IOC_FETCH:
		fapi = (struct pps_fetch_args *)data;
		return (pps_fetch(fapi, pps));
#ifdef FFCLOCK
	case PPS_IOC_FETCH_FFCOUNTER:
		fapi_ffc = (struct pps_fetch_ffc_args *)data;
		if (fapi_ffc->tsformat && fapi_ffc->tsformat !=
		    PPS_TSFMT_TSPEC)
			return (EINVAL);
		if (fapi_ffc->timeout.tv_sec || fapi_ffc->timeout.tv_nsec)
			return (EOPNOTSUPP);
		pps->ppsinfo_ffc.current_mode = pps->ppsparam.mode;
		fapi_ffc->pps_info_buf_ffc = pps->ppsinfo_ffc;
		/* Overwrite timestamps if feedback clock selected. */
		switch (pps->ppsparam.mode & PPS_TSCLK_MASK) {
		case PPS_TSCLK_FBCK:
			fapi_ffc->pps_info_buf_ffc.assert_timestamp =
			    pps->ppsinfo.assert_timestamp;
			fapi_ffc->pps_info_buf_ffc.clear_timestamp =
			    pps->ppsinfo.clear_timestamp;
			break;
		case PPS_TSCLK_FFWD:
			break;
		default:
			break;
		}
		return (0);
#endif /* FFCLOCK */
	case PPS_IOC_KCBIND:
#ifdef PPS_SYNC
		kapi = (struct pps_kcbind_args *)data;
		/* XXX Only root should be able to do this */
		if (kapi->tsformat && kapi->tsformat != PPS_TSFMT_TSPEC)
			return (EINVAL);
		if (kapi->kernel_consumer != PPS_KC_HARDPPS)
			return (EINVAL);
		if (kapi->edge & ~pps->ppscap)
			return (EINVAL);
		pps->kcmode = (kapi->edge & KCMODE_EDGEMASK) |
		    (pps->kcmode & KCMODE_ABIFLAG);
		return (0);
#else
		return (EOPNOTSUPP);
#endif
	default:
		return (ENOIOCTL);
	}
}

#ifdef __rtems__
static int
default_wait(struct pps_state *pps, struct timespec timeout)
{

	(void)pps;
	(void)timeout;

	return (ETIMEDOUT);
}

static void
default_wakeup(struct pps_state *pps)
{

	(void)pps;
}
#endif /* __rtems__ */
void
pps_init(struct pps_state *pps)
{
#ifdef __rtems__
	pps->wait = default_wait;
	pps->wakeup = default_wakeup;
#endif /* __rtems__ */
	pps->ppscap |= PPS_TSFMT_TSPEC | PPS_CANWAIT;
	if (pps->ppscap & PPS_CAPTUREASSERT)
		pps->ppscap |= PPS_OFFSETASSERT;
	if (pps->ppscap & PPS_CAPTURECLEAR)
		pps->ppscap |= PPS_OFFSETCLEAR;
#ifdef FFCLOCK
	pps->ppscap |= PPS_TSCLK_MASK;
#endif
	pps->kcmode &= ~KCMODE_ABIFLAG;
}

void
pps_init_abi(struct pps_state *pps)
{

	pps_init(pps);
	if (pps->driver_abi > 0) {
		pps->kcmode |= KCMODE_ABIFLAG;
		pps->kernel_abi = PPS_ABI_VERSION;
	}
}

void
pps_capture(struct pps_state *pps)
{
	struct timehands *th;

	KASSERT(pps != NULL, ("NULL pps pointer in pps_capture"));
	th = timehands;
	pps->capgen = atomic_load_acq_int(&th->th_generation);
	pps->capth = th;
#ifdef FFCLOCK
	pps->capffth = fftimehands;
#endif
	pps->capcount = th->th_counter->tc_get_timecount(th->th_counter);
	atomic_thread_fence_acq();
	if (pps->capgen != th->th_generation)
		pps->capgen = 0;
}

void
pps_event(struct pps_state *pps, int event)
{
	struct bintime bt;
	struct timespec ts, *tsp, *osp;
	uint32_t tcount, *pcount;
	int foff;
	pps_seq_t *pseq;
#ifdef FFCLOCK
	struct timespec *tsp_ffc;
	pps_seq_t *pseq_ffc;
	ffcounter *ffcount;
#endif
#ifdef PPS_SYNC
	int fhard;
#endif

	KASSERT(pps != NULL, ("NULL pps pointer in pps_event"));
	/* Nothing to do if not currently set to capture this event type. */
	if ((event & pps->ppsparam.mode) == 0)
		return;
	/* If the timecounter was wound up underneath us, bail out. */
	if (pps->capgen == 0 || pps->capgen !=
	    atomic_load_acq_int(&pps->capth->th_generation))
		return;

	/* Things would be easier with arrays. */
	if (event == PPS_CAPTUREASSERT) {
		tsp = &pps->ppsinfo.assert_timestamp;
		osp = &pps->ppsparam.assert_offset;
		foff = pps->ppsparam.mode & PPS_OFFSETASSERT;
#ifdef PPS_SYNC
		fhard = pps->kcmode & PPS_CAPTUREASSERT;
#endif
		pcount = &pps->ppscount[0];
		pseq = &pps->ppsinfo.assert_sequence;
#ifdef FFCLOCK
		ffcount = &pps->ppsinfo_ffc.assert_ffcount;
		tsp_ffc = &pps->ppsinfo_ffc.assert_timestamp;
		pseq_ffc = &pps->ppsinfo_ffc.assert_sequence;
#endif
	} else {
		tsp = &pps->ppsinfo.clear_timestamp;
		osp = &pps->ppsparam.clear_offset;
		foff = pps->ppsparam.mode & PPS_OFFSETCLEAR;
#ifdef PPS_SYNC
		fhard = pps->kcmode & PPS_CAPTURECLEAR;
#endif
		pcount = &pps->ppscount[1];
		pseq = &pps->ppsinfo.clear_sequence;
#ifdef FFCLOCK
		ffcount = &pps->ppsinfo_ffc.clear_ffcount;
		tsp_ffc = &pps->ppsinfo_ffc.clear_timestamp;
		pseq_ffc = &pps->ppsinfo_ffc.clear_sequence;
#endif
	}

	/*
	 * If the timecounter changed, we cannot compare the count values, so
	 * we have to drop the rest of the PPS-stuff until the next event.
	 */
	if (pps->ppstc != pps->capth->th_counter) {
		pps->ppstc = pps->capth->th_counter;
		*pcount = pps->capcount;
		pps->ppscount[2] = pps->capcount;
		return;
	}

	/* Convert the count to a timespec. */
	tcount = pps->capcount - pps->capth->th_offset_count;
	tcount &= pps->capth->th_counter->tc_counter_mask;
	bt = pps->capth->th_bintime;
	bintime_addx(&bt, pps->capth->th_scale * tcount);
	bintime2timespec(&bt, &ts);

	/* If the timecounter was wound up underneath us, bail out. */
	atomic_thread_fence_acq();
	if (pps->capgen != pps->capth->th_generation)
		return;

	*pcount = pps->capcount;
	(*pseq)++;
	*tsp = ts;

	if (foff) {
		timespecadd(tsp, osp, tsp);
		if (tsp->tv_nsec < 0) {
			tsp->tv_nsec += 1000000000;
			tsp->tv_sec -= 1;
		}
	}

#ifdef FFCLOCK
	*ffcount = pps->capffth->tick_ffcount + tcount;
	bt = pps->capffth->tick_time;
	ffclock_convert_delta(tcount, pps->capffth->cest.period, &bt);
	bintime_add(&bt, &pps->capffth->tick_time);
	bintime2timespec(&bt, &ts);
	(*pseq_ffc)++;
	*tsp_ffc = ts;
#endif

#ifdef PPS_SYNC
	if (fhard) {
		uint64_t scale;

		/*
		 * Feed the NTP PLL/FLL.
		 * The FLL wants to know how many (hardware) nanoseconds
		 * elapsed since the previous event.
		 */
		tcount = pps->capcount - pps->ppscount[2];
		pps->ppscount[2] = pps->capcount;
		tcount &= pps->capth->th_counter->tc_counter_mask;
		scale = (uint64_t)1 << 63;
		scale /= pps->capth->th_counter->tc_frequency;
		scale *= 2;
		bt.sec = 0;
		bt.frac = 0;
		bintime_addx(&bt, scale * tcount);
		bintime2timespec(&bt, &ts);
		hardpps(tsp, ts.tv_nsec + 1000000000 * ts.tv_sec);
	}
#endif

	/* Wakeup anyone sleeping in pps_fetch().  */
#ifndef __rtems__
	wakeup(pps);
#else /* __rtems__ */
	_Assert(pps->wakeup != NULL);
	(*pps->wakeup)(pps);
#endif /* __rtems__ */
}
#else /* __rtems__ */
/* FIXME: https://devel.rtems.org/ticket/2349 */
#endif /* __rtems__ */

/*
 * Timecounters need to be updated every so often to prevent the hardware
 * counter from overflowing.  Updating also recalculates the cached values
 * used by the get*() family of functions, so their precision depends on
 * the update frequency.
 */

#ifndef __rtems__
static int tc_tick;
SYSCTL_INT(_kern_timecounter, OID_AUTO, tick, CTLFLAG_RD, &tc_tick, 0,
    "Approximate number of hardclock ticks in a millisecond");
#endif /* __rtems__ */

#ifndef __rtems__
void
tc_ticktock(int cnt)
{
	static int count;

	if (mtx_trylock_spin(&tc_setclock_mtx)) {
		count += cnt;
		if (count >= tc_tick) {
			count = 0;
			tc_windup(NULL);
		}
		mtx_unlock_spin(&tc_setclock_mtx);
	}
}
#else /* __rtems__ */
void
_Timecounter_Tick(void)
{
	Per_CPU_Control *cpu_self = _Per_CPU_Get();

	if (_Per_CPU_Is_boot_processor(cpu_self)) {
                tc_windup(NULL);
	}

	_Watchdog_Tick(cpu_self);
}

void
_Timecounter_Tick_simple(uint32_t delta, uint32_t offset,
    ISR_lock_Context *lock_context)
{
	struct bintime bt;
	struct timehands *th;
#if defined(RTEMS_SMP)
	u_int ogen;
#endif

	th = timehands;
#if defined(RTEMS_SMP)
	ogen = th->th_generation;
	th->th_generation = 0;
	atomic_thread_fence_rel();
#endif

	th->th_offset_count = offset;
	bintime_addx(&th->th_offset, th->th_scale * delta);
	bt = th->th_offset;
	bintime_add(&bt, &th->th_boottime);

	/* Update the UTC timestamps used by the get*() functions. */
	th->th_bintime = bt;
	bintime2timeval(&bt, &th->th_microtime);
	bintime2timespec(&bt, &th->th_nanotime);

#if defined(RTEMS_SMP)
	/*
	 * Now that the struct timehands is again consistent, set the new
	 * generation number, making sure to not make it zero.
	 */
	if (++ogen == 0)
		ogen = 1;
	atomic_store_rel_int(&th->th_generation, ogen);
#else
	atomic_store_rel_int(&th->th_generation, th->th_generation + 1);
#endif

	/* Go live with the new struct timehands. */
	time_second = th->th_microtime.tv_sec;
	time_uptime = th->th_offset.sec;

	_Timecounter_Release(lock_context);

	_Watchdog_Tick(_Per_CPU_Get_snapshot());
}
#endif /* __rtems__ */

#ifndef __rtems__
static void __inline
tc_adjprecision(void)
{
	int t;

	if (tc_timepercentage > 0) {
		t = (99 + tc_timepercentage) / tc_timepercentage;
		tc_precexp = fls(t + (t >> 1)) - 1;
		FREQ2BT(hz / tc_tick, &bt_timethreshold);
		FREQ2BT(hz, &bt_tickthreshold);
		bintime_shift(&bt_timethreshold, tc_precexp);
		bintime_shift(&bt_tickthreshold, tc_precexp);
	} else {
		tc_precexp = 31;
		bt_timethreshold.sec = INT_MAX;
		bt_timethreshold.frac = ~(uint64_t)0;
		bt_tickthreshold = bt_timethreshold;
	}
	sbt_timethreshold = bttosbt(bt_timethreshold);
	sbt_tickthreshold = bttosbt(bt_tickthreshold);
}
#endif /* __rtems__ */

#ifndef __rtems__
static int
sysctl_kern_timecounter_adjprecision(SYSCTL_HANDLER_ARGS)
{
	int error, val;

	val = tc_timepercentage;
	error = sysctl_handle_int(oidp, &val, 0, req);
	if (error != 0 || req->newptr == NULL)
		return (error);
	tc_timepercentage = val;
	if (cold)
		goto done;
	tc_adjprecision();
done:
	return (0);
}

/* Set up the requested number of timehands. */
static void
inittimehands(void *dummy)
{
	struct timehands *thp;
	int i;

	TUNABLE_INT_FETCH("kern.timecounter.timehands_count",
	    &timehands_count);
	if (timehands_count < 1)
		timehands_count = 1;
	if (timehands_count > nitems(ths))
		timehands_count = nitems(ths);
	for (i = 1, thp = &ths[0]; i < timehands_count;  thp = &ths[i++])
		thp->th_next = &ths[i];
	thp->th_next = &ths[0];

	TUNABLE_STR_FETCH("kern.timecounter.hardware", tc_from_tunable,
	    sizeof(tc_from_tunable));

	mtx_init(&tc_lock, "tc", NULL, MTX_DEF);
}
SYSINIT(timehands, SI_SUB_TUNABLES, SI_ORDER_ANY, inittimehands, NULL);

static void
inittimecounter(void *dummy)
{
	u_int p;
	int tick_rate;

	/*
	 * Set the initial timeout to
	 * max(1, <approx. number of hardclock ticks in a millisecond>).
	 * People should probably not use the sysctl to set the timeout
	 * to smaller than its initial value, since that value is the
	 * smallest reasonable one.  If they want better timestamps they
	 * should use the non-"get"* functions.
	 */
	if (hz > 1000)
		tc_tick = (hz + 500) / 1000;
	else
		tc_tick = 1;
	tc_adjprecision();
	FREQ2BT(hz, &tick_bt);
	tick_sbt = bttosbt(tick_bt);
	tick_rate = hz / tc_tick;
	FREQ2BT(tick_rate, &tc_tick_bt);
	tc_tick_sbt = bttosbt(tc_tick_bt);
	p = (tc_tick * 1000000) / hz;
	printf("Timecounters tick every %d.%03u msec\n", p / 1000, p % 1000);

#ifdef FFCLOCK
	ffclock_init();
#endif

	/* warm up new timecounter (again) and get rolling. */
	(void)timecounter->tc_get_timecount(timecounter);
	mtx_lock_spin(&tc_setclock_mtx);
	tc_windup(NULL);
	mtx_unlock_spin(&tc_setclock_mtx);
}

SYSINIT(timecounter, SI_SUB_CLOCKS, SI_ORDER_SECOND, inittimecounter, NULL);

/* Cpu tick handling -------------------------------------------------*/

static int cpu_tick_variable;
static uint64_t	cpu_tick_frequency;

DPCPU_DEFINE_STATIC(uint64_t, tc_cpu_ticks_base);
DPCPU_DEFINE_STATIC(unsigned, tc_cpu_ticks_last);

static uint64_t
tc_cpu_ticks(void)
{
	struct timecounter *tc;
	uint64_t res, *base;
	unsigned u, *last;

	critical_enter();
	base = DPCPU_PTR(tc_cpu_ticks_base);
	last = DPCPU_PTR(tc_cpu_ticks_last);
	tc = timehands->th_counter;
	u = tc->tc_get_timecount(tc) & tc->tc_counter_mask;
	if (u < *last)
		*base += (uint64_t)tc->tc_counter_mask + 1;
	*last = u;
	res = u + *base;
	critical_exit();
	return (res);
}

void
cpu_tick_calibration(void)
{
	static time_t last_calib;

	if (time_uptime != last_calib && !(time_uptime & 0xf)) {
		cpu_tick_calibrate(0);
		last_calib = time_uptime;
	}
}

/*
 * This function gets called every 16 seconds on only one designated
 * CPU in the system from hardclock() via cpu_tick_calibration()().
 *
 * Whenever the real time clock is stepped we get called with reset=1
 * to make sure we handle suspend/resume and similar events correctly.
 */

static void
cpu_tick_calibrate(int reset)
{
	static uint64_t c_last;
	uint64_t c_this, c_delta;
	static struct bintime  t_last;
	struct bintime t_this, t_delta;
	uint32_t divi;

	if (reset) {
		/* The clock was stepped, abort & reset */
		t_last.sec = 0;
		return;
	}

	/* we don't calibrate fixed rate cputicks */
	if (!cpu_tick_variable)
		return;

	getbinuptime(&t_this);
	c_this = cpu_ticks();
	if (t_last.sec != 0) {
		c_delta = c_this - c_last;
		t_delta = t_this;
		bintime_sub(&t_delta, &t_last);
		/*
		 * Headroom:
		 * 	2^(64-20) / 16[s] =
		 * 	2^(44) / 16[s] =
		 * 	17.592.186.044.416 / 16 =
		 * 	1.099.511.627.776 [Hz]
		 */
		divi = t_delta.sec << 20;
		divi |= t_delta.frac >> (64 - 20);
		c_delta <<= 20;
		c_delta /= divi;
		if (c_delta > cpu_tick_frequency) {
			if (0 && bootverbose)
				printf("cpu_tick increased to %ju Hz\n",
				    c_delta);
			cpu_tick_frequency = c_delta;
		}
	}
	c_last = c_this;
	t_last = t_this;
}

void
set_cputicker(cpu_tick_f *func, uint64_t freq, unsigned var)
{

	if (func == NULL) {
		cpu_ticks = tc_cpu_ticks;
	} else {
		cpu_tick_frequency = freq;
		cpu_tick_variable = var;
		cpu_ticks = func;
	}
}

uint64_t
cpu_tickrate(void)
{

	if (cpu_ticks == tc_cpu_ticks) 
		return (tc_getfrequency());
	return (cpu_tick_frequency);
}

/*
 * We need to be slightly careful converting cputicks to microseconds.
 * There is plenty of margin in 64 bits of microseconds (half a million
 * years) and in 64 bits at 4 GHz (146 years), but if we do a multiply
 * before divide conversion (to retain precision) we find that the
 * margin shrinks to 1.5 hours (one millionth of 146y).
 * With a three prong approach we never lose significant bits, no
 * matter what the cputick rate and length of timeinterval is.
 */

uint64_t
cputick2usec(uint64_t tick)
{

	if (tick > 18446744073709551LL)		/* floor(2^64 / 1000) */
		return (tick / (cpu_tickrate() / 1000000LL));
	else if (tick > 18446744073709LL)	/* floor(2^64 / 1000000) */
		return ((tick * 1000LL) / (cpu_tickrate() / 1000LL));
	else
		return ((tick * 1000000LL) / cpu_tickrate());
}

cpu_tick_f	*cpu_ticks = tc_cpu_ticks;
#endif /* __rtems__ */

#ifndef __rtems__
static int vdso_th_enable = 1;
static int
sysctl_fast_gettime(SYSCTL_HANDLER_ARGS)
{
	int old_vdso_th_enable, error;

	old_vdso_th_enable = vdso_th_enable;
	error = sysctl_handle_int(oidp, &old_vdso_th_enable, 0, req);
	if (error != 0)
		return (error);
	vdso_th_enable = old_vdso_th_enable;
	return (0);
}
SYSCTL_PROC(_kern_timecounter, OID_AUTO, fast_gettime,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
    NULL, 0, sysctl_fast_gettime, "I", "Enable fast time of day");

uint32_t
tc_fill_vdso_timehands(struct vdso_timehands *vdso_th)
{
	struct timehands *th;
	uint32_t enabled;

	th = timehands;
	vdso_th->th_scale = th->th_scale;
	vdso_th->th_offset_count = th->th_offset_count;
	vdso_th->th_counter_mask = th->th_counter->tc_counter_mask;
	vdso_th->th_offset = th->th_offset;
	vdso_th->th_boottime = th->th_boottime;
	if (th->th_counter->tc_fill_vdso_timehands != NULL) {
		enabled = th->th_counter->tc_fill_vdso_timehands(vdso_th,
		    th->th_counter);
	} else
		enabled = 0;
	if (!vdso_th_enable)
		enabled = 0;
	return (enabled);
}

#ifdef COMPAT_FREEBSD32
uint32_t
tc_fill_vdso_timehands32(struct vdso_timehands32 *vdso_th32)
{
	struct timehands *th;
	uint32_t enabled;

	th = timehands;
	*(uint64_t *)&vdso_th32->th_scale[0] = th->th_scale;
	vdso_th32->th_offset_count = th->th_offset_count;
	vdso_th32->th_counter_mask = th->th_counter->tc_counter_mask;
	vdso_th32->th_offset.sec = th->th_offset.sec;
	*(uint64_t *)&vdso_th32->th_offset.frac[0] = th->th_offset.frac;
	vdso_th32->th_boottime.sec = th->th_boottime.sec;
	*(uint64_t *)&vdso_th32->th_boottime.frac[0] = th->th_boottime.frac;
	if (th->th_counter->tc_fill_vdso_timehands32 != NULL) {
		enabled = th->th_counter->tc_fill_vdso_timehands32(vdso_th32,
		    th->th_counter);
	} else
		enabled = 0;
	if (!vdso_th_enable)
		enabled = 0;
	return (enabled);
}
#endif

#include "opt_ddb.h"
#ifdef DDB
#include <ddb/ddb.h>

DB_SHOW_COMMAND(timecounter, db_show_timecounter)
{
	struct timehands *th;
	struct timecounter *tc;
	u_int val1, val2;

	th = timehands;
	tc = th->th_counter;
	val1 = tc->tc_get_timecount(tc);
	__compiler_membar();
	val2 = tc->tc_get_timecount(tc);

	db_printf("timecounter %p %s\n", tc, tc->tc_name);
	db_printf("  mask %#x freq %ju qual %d flags %#x priv %p\n",
	    tc->tc_counter_mask, (uintmax_t)tc->tc_frequency, tc->tc_quality,
	    tc->tc_flags, tc->tc_priv);
	db_printf("  val %#x %#x\n", val1, val2);
	db_printf("timehands adj %#jx scale %#jx ldelta %d off_cnt %d gen %d\n",
	    (uintmax_t)th->th_adjustment, (uintmax_t)th->th_scale,
	    th->th_large_delta, th->th_offset_count, th->th_generation);
	db_printf("  offset %jd %jd boottime %jd %jd\n",
	    (intmax_t)th->th_offset.sec, (uintmax_t)th->th_offset.frac,
	    (intmax_t)th->th_boottime.sec, (uintmax_t)th->th_boottime.frac);
}
#endif
#else /* __rtems__ */
RTEMS_ALIAS(_Timecounter_Nanotime)
void rtems_clock_get_realtime(struct timespec *);

RTEMS_ALIAS(_Timecounter_Bintime)
void rtems_clock_get_realtime_bintime(struct bintime *);

RTEMS_ALIAS(_Timecounter_Microtime)
void rtems_clock_get_realtime_timeval(struct timeval *);

RTEMS_ALIAS(_Timecounter_Getnanotime)
void rtems_clock_get_realtime_coarse(struct timespec *);

RTEMS_ALIAS(_Timecounter_Getbintime)
void rtems_clock_get_realtime_coarse_bintime(struct bintime *);

RTEMS_ALIAS(_Timecounter_Getmicrotime)
void rtems_clock_get_realtime_coarse_timeval(struct timeval *);

RTEMS_ALIAS(_Timecounter_Nanouptime)
void rtems_clock_get_monotonic(struct timespec *);

RTEMS_ALIAS(_Timecounter_Binuptime)
void rtems_clock_get_monotonic_bintime(struct bintime *);

RTEMS_ALIAS(_Timecounter_Sbinuptime)
sbintime_t rtems_clock_get_monotonic_sbintime(void);

RTEMS_ALIAS(_Timecounter_Microuptime)
void rtems_clock_get_monotonic_timeval(struct timeval *);

RTEMS_ALIAS(_Timecounter_Getnanouptime)
void rtems_clock_get_monotonic_coarse(struct timespec *);

RTEMS_ALIAS(_Timecounter_Getbinuptime)
void rtems_clock_get_monotonic_coarse_bintime(struct bintime *);

RTEMS_ALIAS(_Timecounter_Getmicrouptime)
void rtems_clock_get_monotonic_coarse_timeval(struct timeval *);

RTEMS_ALIAS(_Timecounter_Getboottimebin)
void rtems_clock_get_boot_time_bintime(struct bintime *);

RTEMS_ALIAS(_Timecounter_Getboottime)
void rtems_clock_get_boot_time_timeval(struct timeval *);
#endif /* __rtems__ */