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/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1990 The Regents of the University of California.
* Copyright (c) 2010 Alexander Motin <mav@FreeBSD.org>
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz and Don Ahn.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from: @(#)clock.c 7.2 (Berkeley) 5/12/91
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
/* Generic x86 routines to handle delay */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/timetc.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/sched.h>
#include <machine/clock.h>
#include <machine/cpu.h>
#include <x86/init.h>
static u_int
get_tsc(__unused struct timecounter *tc)
{
return (rdtsc32());
}
static int
delay_tc(int n)
{
struct timecounter *tc;
timecounter_get_t *func;
uint64_t end, freq, now;
u_int last, mask, u;
tc = timecounter;
freq = atomic_load_acq_64(&tsc_freq);
if (tsc_is_invariant && freq != 0) {
func = get_tsc;
mask = ~0u;
} else {
if (tc->tc_quality <= 0)
return (0);
func = tc->tc_get_timecount;
mask = tc->tc_counter_mask;
freq = tc->tc_frequency;
}
now = 0;
end = freq * n / 1000000;
if (func == get_tsc)
sched_pin();
last = func(tc) & mask;
do {
cpu_spinwait();
u = func(tc) & mask;
if (u < last)
now += mask - last + u + 1;
else
now += u - last;
last = u;
} while (now < end);
if (func == get_tsc)
sched_unpin();
return (1);
}
void
DELAY(int n)
{
if (delay_tc(n))
return;
init_ops.early_delay(n);
}
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