2 * Copyright (c) 1988 University of Utah.
3 * Copyright (c) 1982, 1990, 1993
4 * The Regents of the University of California.
5 * Copyright (c) 2011 The FreeBSD Foundation
8 * This code is derived from software contributed to Berkeley by
9 * the Systems Programming Group of the University of Utah Computer
12 * Portions of this software were developed by Julien Ridoux at the University
13 * of Melbourne under sponsorship from the FreeBSD Foundation.
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 * 3. Neither the name of the University nor the names of its contributors
24 * may be used to endorse or promote products derived from this software
25 * without specific prior written permission.
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * from: Utah $Hdr: clock.c 1.18 91/01/21$
40 * from: @(#)clock.c 8.2 (Berkeley) 1/12/94
41 * from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
43 * from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
47 * Helpers for time-of-day clocks. This is useful for architectures that need
48 * support multiple models of such clocks, and generally serves to make the
49 * code more machine-independent.
50 * If the clock in question can also be used as a time counter, the driver
51 * needs to initiate this.
52 * This code is not yet used by all architectures.
55 #include <sys/cdefs.h>
56 __FBSDID("$FreeBSD$");
58 #include "opt_ffclock.h"
60 #include <sys/param.h>
61 #include <sys/systm.h>
62 #include <sys/kernel.h>
64 #include <sys/clock.h>
66 #include <sys/malloc.h>
68 #include <sys/sysctl.h>
69 #include <sys/taskqueue.h>
71 #include <sys/timeffc.h>
73 #include <sys/timetc.h>
77 /* XXX: should be kern. now, it's no longer machdep. */
78 static int disable_rtc_set;
79 SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set, CTLFLAG_RW, &disable_rtc_set,
80 0, "Disallow adjusting time-of-day clock");
83 * An instance of a realtime clock. A list of these tracks all the registered
84 * clocks in the system.
86 * The resadj member is used to apply a "resolution adjustment" equal to half
87 * the clock's resolution, which is useful mainly on clocks with a whole-second
88 * resolution. Because the clock truncates the fractional part, adding half the
89 * resolution performs 4/5 rounding. The same adjustment is applied to the
90 * times returned from clock_gettime(), because the fraction returned will
91 * always be zero, but on average the actual fraction at the time of the call
98 struct timespec resadj;
99 LIST_ENTRY(rtc_instance)
104 * Clocks are updated using a task running on taskqueue_thread.
106 static void settime_task_func(void *arg, int pending);
107 static struct task settime_task = TASK_INITIALIZER(0, settime_task_func, NULL);
110 * Registered clocks are kept in a list which is sorted by resolution; the more
111 * accurate clocks get the first shot at providing the time.
113 LIST_HEAD(rtc_listhead, rtc_instance);
114 static struct rtc_listhead rtc_list = LIST_HEAD_INITIALIZER(rtc_list);
115 static struct sx rtc_list_lock;
116 SX_SYSINIT(rtc_list_lock_init, &rtc_list_lock, "rtc list");
119 * On the task thread, invoke the clock_settime() method of each registered
120 * clock. Do so holding only an sxlock, so that clock drivers are free to do
121 * whatever kind of locking or sleeping they need to.
124 settime_task_func(void *arg, int pending)
127 struct rtc_instance *rtc;
129 sx_xlock(&rtc_list_lock);
130 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
131 if (!(rtc->flags & CLOCKF_SETTIME_NO_TS)) {
133 if (!(rtc->flags & CLOCKF_SETTIME_NO_ADJ)) {
134 ts.tv_sec -= utc_offset();
135 timespecadd(&ts, &rtc->resadj);
141 CLOCK_SETTIME(rtc->clockdev, &ts);
143 sx_xunlock(&rtc_list_lock);
147 clock_register_flags(device_t clockdev, long resolution, int flags)
149 struct rtc_instance *rtc, *newrtc;
151 newrtc = malloc(sizeof(*newrtc), M_DEVBUF, M_WAITOK);
152 newrtc->clockdev = clockdev;
153 newrtc->resolution = (int)resolution;
154 newrtc->flags = flags;
155 newrtc->resadj.tv_sec = newrtc->resolution / 2 / 1000000;
156 newrtc->resadj.tv_nsec = newrtc->resolution / 2 % 1000000 * 1000;
158 sx_xlock(&rtc_list_lock);
159 if (LIST_EMPTY(&rtc_list)) {
160 LIST_INSERT_HEAD(&rtc_list, newrtc, rtc_entries);
162 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
163 if (rtc->resolution > newrtc->resolution) {
164 LIST_INSERT_BEFORE(rtc, newrtc, rtc_entries);
166 } else if (LIST_NEXT(rtc, rtc_entries) == NULL) {
167 LIST_INSERT_AFTER(rtc, newrtc, rtc_entries);
172 sx_xunlock(&rtc_list_lock);
174 device_printf(clockdev,
175 "registered as a time-of-day clock, resolution %d.%6.6ds\n",
176 newrtc->resolution / 1000000, newrtc->resolution % 1000000);
180 clock_register(device_t dev, long res)
183 clock_register_flags(dev, res, 0);
187 clock_unregister(device_t clockdev)
189 struct rtc_instance *rtc, *tmp;
191 sx_xlock(&rtc_list_lock);
192 LIST_FOREACH_SAFE(rtc, &rtc_list, rtc_entries, tmp) {
193 if (rtc->clockdev == clockdev) {
194 LIST_REMOVE(rtc, rtc_entries);
198 sx_xunlock(&rtc_list_lock);
202 * Initialize the system time. Must be called from a context which does not
203 * restrict any locking or sleeping that clock drivers may need to do.
205 * First attempt to get the time from a registered realtime clock. The clocks
206 * are queried in order of resolution until one provides the time. If no clock
207 * can provide the current time, use the 'base' time provided by the caller, if
208 * non-zero. The 'base' time is potentially highly inaccurate, such as the last
209 * known good value of the system clock, or even a filesystem last-updated
210 * timestamp. It is used to prevent system time from appearing to move
214 inittodr(time_t base)
217 struct rtc_instance *rtc;
221 sx_xlock(&rtc_list_lock);
222 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
223 if ((error = CLOCK_GETTIME(rtc->clockdev, &ts)) != 0)
225 if (ts.tv_sec < 0 || ts.tv_nsec < 0) {
229 if (!(rtc->flags & CLOCKF_GETTIME_NO_ADJ)) {
230 timespecadd(&ts, &rtc->resadj);
231 ts.tv_sec += utc_offset();
234 device_printf(rtc->clockdev,
235 "providing initial system time\n");
238 sx_xunlock(&rtc_list_lock);
241 * Do not report errors from each clock; it is expected that some clocks
242 * cannot provide results in some situations. Only report problems when
243 * no clocks could provide the time.
248 printf("Warning: no time-of-day clock registered, ");
251 printf("Warning: bad time from time-of-day clock, ");
254 printf("Error reading time-of-day clock (%d), ", error);
257 printf("system time will not be set accurately\n");
258 ts.tv_sec = (base > 0) ? base : -1;
262 if (ts.tv_sec >= 0) {
265 ffclock_reset_clock(&ts);
271 * Write system time back to all registered clocks, unless disabled by admin.
272 * This can be called from a context that restricts locking and/or sleeping; the
273 * actual updating is done asynchronously on a task thread.
282 taskqueue_enqueue(taskqueue_thread, &settime_task);