2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1990 The Regents of the University of California.
5 * Copyright (c) 2010 Alexander Motin <mav@FreeBSD.org>
8 * This code is derived from software contributed to Berkeley by
9 * William Jolitz and Don Ahn.
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * from: @(#)clock.c 7.2 (Berkeley) 5/12/91
38 #include <sys/cdefs.h>
39 __FBSDID("$FreeBSD$");
41 /* Generic x86 routines to handle delay */
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/timetc.h>
47 #include <sys/kernel.h>
48 #include <sys/sched.h>
50 #include <machine/clock.h>
51 #include <machine/cpu.h>
55 get_tsc(__unused struct timecounter *tc)
64 struct timecounter *tc;
65 timecounter_get_t *func;
66 uint64_t end, freq, now;
70 freq = atomic_load_acq_64(&tsc_freq);
71 if (tsc_is_invariant && freq != 0) {
75 if (tc->tc_quality <= 0)
77 func = tc->tc_get_timecount;
78 mask = tc->tc_counter_mask;
79 freq = tc->tc_frequency;
82 end = freq * n / 1000000;
85 last = func(tc) & mask;
90 now += mask - last + u + 1;
107 init_ops.early_delay(n);