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freebsd/sys/kern/subr_rtc.c
Lawrence Stewart b0fdc83713 Core structure and functions to support a feed-forward clock within the kernel.
Implement ffcounter, a monotonically increasing cumulative counter on top of the
active timecounter. Provide low-level functions to read the ffcounter and
convert it to absolute time or a time interval in seconds using the current
ffclock estimates, which track the drift of the oscillator. Add a ring of
fftimehands to track passing of time on each kernel tick and pick up updates of
ffclock estimates.

Committed on behalf of Julien Ridoux and Darryl Veitch from the University of
Melbourne, Australia, as part of the FreeBSD Foundation funded "Feed-Forward
Clock Synchronization Algorithms" project.

For more information, see http://www.synclab.org/radclock/

Submitted by:	Julien Ridoux (jridoux at unimelb edu au)
2011-11-19 14:10:16 +00:00

179 lines
5.5 KiB
C

/*-
* Copyright (c) 1988 University of Utah.
* Copyright (c) 1982, 1990, 1993
* The Regents of the University of California.
* Copyright (c) 2011 The FreeBSD Foundation
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* Portions of this software were developed by Julien Ridoux at the University
* of Melbourne under sponsorship from the FreeBSD Foundation.
*
* 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.
* 4. 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: Utah $Hdr: clock.c 1.18 91/01/21$
* from: @(#)clock.c 8.2 (Berkeley) 1/12/94
* from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
* and
* from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
*/
/*
* Helpers for time-of-day clocks. This is useful for architectures that need
* support multiple models of such clocks, and generally serves to make the
* code more machine-independent.
* If the clock in question can also be used as a time counter, the driver
* needs to initiate this.
* This code is not yet used by all architectures.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ffclock.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/clock.h>
#include <sys/sysctl.h>
#ifdef FFCLOCK
#include <sys/timeffc.h>
#endif
#include <sys/timetc.h>
#include "clock_if.h"
static device_t clock_dev = NULL;
static long clock_res;
static struct timespec clock_adj;
/* XXX: should be kern. now, it's no longer machdep. */
static int disable_rtc_set;
SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set, CTLFLAG_RW, &disable_rtc_set,
0, "Disallow adjusting time-of-day clock");
void
clock_register(device_t dev, long res) /* res has units of microseconds */
{
if (clock_dev != NULL) {
if (clock_res > res) {
if (bootverbose)
device_printf(dev, "not installed as "
"time-of-day clock: clock %s has higher "
"resolution\n", device_get_name(clock_dev));
return;
}
if (bootverbose)
device_printf(clock_dev, "removed as "
"time-of-day clock: clock %s has higher "
"resolution\n", device_get_name(dev));
}
clock_dev = dev;
clock_res = res;
clock_adj.tv_sec = res / 2 / 1000000;
clock_adj.tv_nsec = res / 2 % 1000000 * 1000;
if (bootverbose)
device_printf(dev, "registered as a time-of-day clock "
"(resolution %ldus, adjustment %jd.%09jds)\n", res,
(intmax_t)clock_adj.tv_sec, (intmax_t)clock_adj.tv_nsec);
}
/*
* inittodr and settodr derived from the i386 versions written
* by Christoph Robitschko <chmr@edvz.tu-graz.ac.at>, reintroduced and
* updated by Chris Stenton <chris@gnome.co.uk> 8/10/94
*/
/*
* Initialize the time of day register, based on the time base which is, e.g.
* from a filesystem.
*/
void
inittodr(time_t base)
{
struct timespec ts;
int error;
if (clock_dev == NULL) {
printf("warning: no time-of-day clock registered, system time "
"will not be set accurately\n");
goto wrong_time;
}
/* XXX: We should poll all registered RTCs in case of failure */
error = CLOCK_GETTIME(clock_dev, &ts);
if (error != 0 && error != EINVAL) {
printf("warning: clock_gettime failed (%d), the system time "
"will not be set accurately\n", error);
goto wrong_time;
}
if (error == EINVAL || ts.tv_sec < 0) {
printf("Invalid time in real time clock.\n"
"Check and reset the date immediately!\n");
goto wrong_time;
}
ts.tv_sec += utc_offset();
timespecadd(&ts, &clock_adj);
tc_setclock(&ts);
#ifdef FFCLOCK
ffclock_reset_clock(&ts);
#endif
return;
wrong_time:
if (base > 0) {
ts.tv_sec = base;
ts.tv_nsec = 0;
tc_setclock(&ts);
}
}
/*
* Write system time back to RTC
*/
void
resettodr(void)
{
struct timespec ts;
int error;
if (disable_rtc_set || clock_dev == NULL)
return;
getnanotime(&ts);
timespecadd(&ts, &clock_adj);
ts.tv_sec -= utc_offset();
/* XXX: We should really set all registered RTCs */
if ((error = CLOCK_SETTIME(clock_dev, &ts)) != 0)
printf("warning: clock_settime failed (%d), time-of-day clock "
"not adjusted to system time\n", error);
}