2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1988 University of Utah.
5 * Copyright (c) 1982, 1990, 1993
6 * The Regents of the University of California.
7 * Copyright (c) 2011 The FreeBSD Foundation
10 * This code is derived from software contributed to Berkeley by
11 * the Systems Programming Group of the University of Utah Computer
14 * Portions of this software were developed by Julien Ridoux at the University
15 * of Melbourne under sponsorship from the FreeBSD Foundation.
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
20 * 1. Redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution.
25 * 3. Neither the name of the University nor the names of its contributors
26 * may be used to endorse or promote products derived from this software
27 * without specific prior written permission.
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
41 * from: Utah $Hdr: clock.c 1.18 91/01/21$
42 * from: @(#)clock.c 8.2 (Berkeley) 1/12/94
43 * from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
45 * from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
49 * Helpers for time-of-day clocks. This is useful for architectures that need
50 * support multiple models of such clocks, and generally serves to make the
51 * code more machine-independent.
52 * If the clock in question can also be used as a time counter, the driver
53 * needs to initiate this.
54 * This code is not yet used by all architectures.
57 #include <sys/cdefs.h>
58 __FBSDID("$FreeBSD$");
60 #include "opt_ffclock.h"
62 #include <sys/param.h>
63 #include <sys/systm.h>
64 #include <sys/kernel.h>
66 #include <sys/clock.h>
68 #include <sys/malloc.h>
70 #include <sys/sysctl.h>
71 #include <sys/taskqueue.h>
73 #include <sys/timeffc.h>
75 #include <sys/timetc.h>
79 /* XXX: should be kern. now, it's no longer machdep. */
80 static int disable_rtc_set;
81 SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set, CTLFLAG_RW, &disable_rtc_set,
82 0, "Disallow adjusting time-of-day clock");
85 * An instance of a realtime clock. A list of these tracks all the registered
86 * clocks in the system.
88 * The resadj member is used to apply a "resolution adjustment" equal to half
89 * the clock's resolution, which is useful mainly on clocks with a whole-second
90 * resolution. Because the clock truncates the fractional part, adding half the
91 * resolution performs 4/5 rounding. The same adjustment is applied to the
92 * times returned from clock_gettime(), because the fraction returned will
93 * always be zero, but on average the actual fraction at the time of the call
101 struct timespec resadj;
104 LIST_ENTRY(rtc_instance)
109 * Clocks are updated using a task running on taskqueue_thread.
111 static void settime_task_func(void *arg, int pending);
114 * Registered clocks are kept in a list which is sorted by resolution; the more
115 * accurate clocks get the first shot at providing the time.
117 LIST_HEAD(rtc_listhead, rtc_instance);
118 static struct rtc_listhead rtc_list = LIST_HEAD_INITIALIZER(rtc_list);
119 static struct sx rtc_list_lock;
120 SX_SYSINIT(rtc_list_lock_init, &rtc_list_lock, "rtc list");
123 * On the task thread, invoke the clock_settime() method of the clock. Do so
124 * holding no locks, so that clock drivers are free to do whatever kind of
125 * locking or sleeping they need to.
128 settime_task_func(void *arg, int pending)
131 struct rtc_instance *rtc;
134 if (!(rtc->flags & CLOCKF_SETTIME_NO_TS)) {
136 if (!(rtc->flags & CLOCKF_SETTIME_NO_ADJ)) {
137 ts.tv_sec -= utc_offset();
138 timespecadd(&ts, &rtc->resadj);
144 CLOCK_SETTIME(rtc->clockdev, &ts);
148 clock_register_flags(device_t clockdev, long resolution, int flags)
150 struct rtc_instance *rtc, *newrtc;
152 newrtc = malloc(sizeof(*newrtc), M_DEVBUF, M_WAITOK);
153 newrtc->clockdev = clockdev;
154 newrtc->resolution = (int)resolution;
155 newrtc->flags = flags;
157 newrtc->resadj.tv_sec = newrtc->resolution / 2 / 1000000;
158 newrtc->resadj.tv_nsec = newrtc->resolution / 2 % 1000000 * 1000;
159 TIMEOUT_TASK_INIT(taskqueue_thread, &newrtc->stask, 0,
160 settime_task_func, newrtc);
162 sx_xlock(&rtc_list_lock);
163 if (LIST_EMPTY(&rtc_list)) {
164 LIST_INSERT_HEAD(&rtc_list, newrtc, rtc_entries);
166 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
167 if (rtc->resolution > newrtc->resolution) {
168 LIST_INSERT_BEFORE(rtc, newrtc, rtc_entries);
170 } else if (LIST_NEXT(rtc, rtc_entries) == NULL) {
171 LIST_INSERT_AFTER(rtc, newrtc, rtc_entries);
176 sx_xunlock(&rtc_list_lock);
178 device_printf(clockdev,
179 "registered as a time-of-day clock, resolution %d.%6.6ds\n",
180 newrtc->resolution / 1000000, newrtc->resolution % 1000000);
184 clock_register(device_t dev, long res)
187 clock_register_flags(dev, res, 0);
191 clock_unregister(device_t clockdev)
193 struct rtc_instance *rtc, *tmp;
195 sx_xlock(&rtc_list_lock);
196 LIST_FOREACH_SAFE(rtc, &rtc_list, rtc_entries, tmp) {
197 if (rtc->clockdev == clockdev) {
198 LIST_REMOVE(rtc, rtc_entries);
202 sx_xunlock(&rtc_list_lock);
204 taskqueue_cancel_timeout(taskqueue_thread, &rtc->stask, NULL);
205 taskqueue_drain_timeout(taskqueue_thread, &rtc->stask);
211 clock_schedule(device_t clockdev, u_int offsetns)
213 struct rtc_instance *rtc;
215 sx_xlock(&rtc_list_lock);
216 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
217 if (rtc->clockdev == clockdev) {
218 rtc->schedns = offsetns;
222 sx_xunlock(&rtc_list_lock);
226 * Initialize the system time. Must be called from a context which does not
227 * restrict any locking or sleeping that clock drivers may need to do.
229 * First attempt to get the time from a registered realtime clock. The clocks
230 * are queried in order of resolution until one provides the time. If no clock
231 * can provide the current time, use the 'base' time provided by the caller, if
232 * non-zero. The 'base' time is potentially highly inaccurate, such as the last
233 * known good value of the system clock, or even a filesystem last-updated
234 * timestamp. It is used to prevent system time from appearing to move
238 inittodr(time_t base)
241 struct rtc_instance *rtc;
245 sx_xlock(&rtc_list_lock);
246 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
247 if ((error = CLOCK_GETTIME(rtc->clockdev, &ts)) != 0)
249 if (ts.tv_sec < 0 || ts.tv_nsec < 0) {
253 if (!(rtc->flags & CLOCKF_GETTIME_NO_ADJ)) {
254 timespecadd(&ts, &rtc->resadj);
255 ts.tv_sec += utc_offset();
258 device_printf(rtc->clockdev,
259 "providing initial system time\n");
262 sx_xunlock(&rtc_list_lock);
265 * Do not report errors from each clock; it is expected that some clocks
266 * cannot provide results in some situations. Only report problems when
267 * no clocks could provide the time.
272 printf("Warning: no time-of-day clock registered, ");
275 printf("Warning: bad time from time-of-day clock, ");
278 printf("Error reading time-of-day clock (%d), ", error);
281 printf("system time will not be set accurately\n");
282 ts.tv_sec = (base > 0) ? base : -1;
286 if (ts.tv_sec >= 0) {
289 ffclock_reset_clock(&ts);
295 * Write system time back to all registered clocks, unless disabled by admin.
296 * This can be called from a context that restricts locking and/or sleeping; the
297 * actual updating is done asynchronously on a task thread.
303 struct rtc_instance *rtc;
310 sx_xlock(&rtc_list_lock);
311 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
312 if (rtc->schedns != 0) {
314 waitns = rtc->schedns - now.tv_nsec;
316 waitns += 1000000000;
317 sbt = nstosbt(waitns);
320 taskqueue_enqueue_timeout_sbt(taskqueue_thread,
321 &rtc->stask, -sbt, 0, C_PREL(31));
323 sx_xunlock(&rtc_list_lock);