subr_rtc.c revision 188055 
1/*-
2 * Copyright (c) 1988 University of Utah.
3 * Copyright (c) 1982, 1990, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * the Systems Programming Group of the University of Utah Computer
8 * Science Department.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 *	from: Utah $Hdr: clock.c 1.18 91/01/21$
35 *	from: @(#)clock.c	8.2 (Berkeley) 1/12/94
36 *	from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
37 *	and
38 *	from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
39 */
40
41/*
42 * Helpers for time-of-day clocks. This is useful for architectures that need
43 * support multiple models of such clocks, and generally serves to make the
44 * code more machine-independent.
45 * If the clock in question can also be used as a time counter, the driver
46 * needs to initiate this.
47 * This code is not yet used by all architectures.
48 */
49
50#include <sys/cdefs.h>
51__FBSDID("$FreeBSD: head/sys/kern/subr_rtc.c 188055 2009-02-03 07:50:01Z imp $");
52
53#include <sys/param.h>
54#include <sys/systm.h>
55#include <sys/kernel.h>
56#include <sys/bus.h>
57#include <sys/clock.h>
58#include <sys/sysctl.h>
59#include <sys/timetc.h>
60
61#include "clock_if.h"
62
63static device_t clock_dev = NULL;
64static long clock_res;
65
66/* XXX: should be kern. now, it's no longer machdep.  */
67static int disable_rtc_set;
68SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set,
69	CTLFLAG_RW, &disable_rtc_set, 0, "");
70
71void
72clock_register(device_t dev, long res)	/* res has units of microseconds */
73{
74
75	if (clock_dev != NULL) {
76		if (clock_res > res) {
77			if (bootverbose) {
78				device_printf(dev, "not installed as "
79				    "time-of-day clock: clock %s has higher "
80				    "resolution\n", device_get_name(clock_dev));
81			}
82			return;
83		} else {
84			if (bootverbose) {
85				device_printf(clock_dev, "removed as "
86				    "time-of-day clock: clock %s has higher "
87				    "resolution\n", device_get_name(dev));
88			}
89		}
90	}
91	clock_dev = dev;
92	clock_res = res;
93	if (bootverbose) {
94		device_printf(dev, "registered as a time-of-day clock "
95		    "(resolution %ldus)\n", res);
96	}
97}
98
99/*
100 * inittodr and settodr derived from the i386 versions written
101 * by Christoph Robitschko <chmr@edvz.tu-graz.ac.at>,  reintroduced and
102 * updated by Chris Stenton <chris@gnome.co.uk> 8/10/94
103 */
104
105/*
106 * Initialize the time of day register, based on the time base which is, e.g.
107 * from a filesystem.
108 */
109void
110inittodr(time_t base)
111{
112	struct timespec diff, ref, ts;
113	int error;
114
115	if (base) {
116		ref.tv_sec = base;
117		ref.tv_nsec = 0;
118		tc_setclock(&ref);
119	}
120
121	if (clock_dev == NULL) {
122		printf("warning: no time-of-day clock registered, system time "
123		    "will not be set accurately\n");
124		return;
125	}
126	/* XXX: We should poll all registered RTCs in case of failure */
127	error = CLOCK_GETTIME(clock_dev, &ts);
128	if (error != 0 && error != EINVAL) {
129		printf("warning: clock_gettime failed (%d), the system time "
130		    "will not be set accurately\n", error);
131		return;
132	}
133	if (error == EINVAL || ts.tv_sec < 0) {
134		printf("Invalid time in real time clock.\n");
135		printf("Check and reset the date immediately!\n");
136	}
137
138	ts.tv_sec += utc_offset();
139
140	if (timespeccmp(&ref, &ts, >)) {
141		diff = ref;
142		timespecsub(&ref, &ts);
143	} else {
144		diff = ts;
145		timespecsub(&diff, &ref);
146	}
147	if (ts.tv_sec >= 2) {
148		/* badly off, adjust it */
149		tc_setclock(&ts);
150	}
151}
152
153/*
154 * Write system time back to RTC
155 */
156void
157resettodr(void)
158{
159	struct timespec ts;
160	int error;
161
162	if (disable_rtc_set || clock_dev == NULL)
163		return;
164
165	getnanotime(&ts);
166	ts.tv_sec -= utc_offset();
167	/* XXX: We should really set all registered RTCs */
168	if ((error = CLOCK_SETTIME(clock_dev, &ts)) != 0) {
169		printf("warning: clock_settime failed (%d), time-of-day clock "
170		    "not adjusted to system time\n", error);
171		return;
172	}
173}
174