aboutsummaryrefslogtreecommitdiff
path: root/sys/kern/subr_rtc.c
blob: 82c276f210a2271ad4ff4db28ff6102e2a7e3e9a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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.
 * 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: 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/lock.h>
#include <sys/malloc.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/taskqueue.h>
#ifdef FFCLOCK
#include <sys/timeffc.h>
#endif
#include <sys/timetc.h>

#include "clock_if.h"

static int show_io;
SYSCTL_INT(_debug, OID_AUTO, clock_show_io, CTLFLAG_RWTUN, &show_io, 0,
    "Enable debug printing of RTC clock I/O; 1=reads, 2=writes, 3=both.");

static int sysctl_clock_do_io(SYSCTL_HANDLER_ARGS);
SYSCTL_PROC(_debug, OID_AUTO, clock_do_io, CTLTYPE_INT | CTLFLAG_RW,
    0, 0, sysctl_clock_do_io, "I",
    "Trigger one-time IO on RTC clocks; 1=read (and discard), 2=write");

/* 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");

/*
 * An instance of a realtime clock.  A list of these tracks all the registered
 * clocks in the system.
 *
 * The resadj member is used to apply a "resolution adjustment" equal to half
 * the clock's resolution, which is useful mainly on clocks with a whole-second
 * resolution.  Because the clock truncates the fractional part, adding half the
 * resolution performs 4/5 rounding.  The same adjustment is applied to the
 * times returned from clock_gettime(), because the fraction returned will
 * always be zero, but on average the actual fraction at the time of the call
 * should be about .5.
 */
struct rtc_instance {
	device_t	clockdev;
	int		resolution;
	int		flags;
	u_int		schedns;
	struct timespec resadj;
	struct timeout_task
			stask;
	LIST_ENTRY(rtc_instance)
			rtc_entries;
};

/*
 * Clocks are updated using a task running on taskqueue_thread.
 */
static void settime_task_func(void *arg, int pending);

/*
 * Registered clocks are kept in a list which is sorted by resolution; the more
 * accurate clocks get the first shot at providing the time.
 */
LIST_HEAD(rtc_listhead, rtc_instance);
static struct rtc_listhead rtc_list = LIST_HEAD_INITIALIZER(rtc_list);
static struct sx rtc_list_lock;
SX_SYSINIT(rtc_list_lock_init, &rtc_list_lock, "rtc list");

/*
 * On the task thread, invoke the clock_settime() method of the clock.  Do so
 * holding no locks, so that clock drivers are free to do whatever kind of
 * locking or sleeping they need to.
 */
static void
settime_task_func(void *arg, int pending)
{
	struct timespec ts;
	struct rtc_instance *rtc;

	rtc = arg;
	if (!(rtc->flags & CLOCKF_SETTIME_NO_TS)) {
		getnanotime(&ts);
		if (!(rtc->flags & CLOCKF_SETTIME_NO_ADJ)) {
			ts.tv_sec -= utc_offset();
			timespecadd(&ts, &rtc->resadj, &ts);
		}
	} else {
		ts.tv_sec  = 0;
		ts.tv_nsec = 0;
	}
	CLOCK_SETTIME(rtc->clockdev, &ts);
}

static void
clock_dbgprint_hdr(device_t dev, int rw)
{
	struct timespec now;

	getnanotime(&now);
	device_printf(dev, "%s at ", (rw & CLOCK_DBG_READ) ? "read " : "write");
	clock_print_ts(&now, 9);
	printf(": "); 
}

void
clock_dbgprint_bcd(device_t dev, int rw, const struct bcd_clocktime *bct)
{

	if (show_io & rw) {
		clock_dbgprint_hdr(dev, rw);
		clock_print_bcd(bct, 9);
		printf("\n");
	}
}

void
clock_dbgprint_ct(device_t dev, int rw, const struct clocktime *ct)
{

	if (show_io & rw) {
		clock_dbgprint_hdr(dev, rw);
		clock_print_ct(ct, 9);
		printf("\n");
	}
}

void
clock_dbgprint_err(device_t dev, int rw, int err)
{

	if (show_io & rw) {
		clock_dbgprint_hdr(dev, rw);
		printf("error = %d\n", err);
	}
}

void
clock_dbgprint_ts(device_t dev, int rw, const struct timespec *ts)
{

	if (show_io & rw) {
		clock_dbgprint_hdr(dev, rw);
		clock_print_ts(ts, 9);
		printf("\n");
	}
}

void
clock_register_flags(device_t clockdev, long resolution, int flags)
{
	struct rtc_instance *rtc, *newrtc;

	newrtc = malloc(sizeof(*newrtc), M_DEVBUF, M_WAITOK);
	newrtc->clockdev = clockdev;
	newrtc->resolution = (int)resolution;
	newrtc->flags = flags;
	newrtc->schedns = 0;
	newrtc->resadj.tv_sec  = newrtc->resolution / 2 / 1000000;
	newrtc->resadj.tv_nsec = newrtc->resolution / 2 % 1000000 * 1000;
	TIMEOUT_TASK_INIT(taskqueue_thread, &newrtc->stask, 0,
		    settime_task_func, newrtc);

	sx_xlock(&rtc_list_lock);
	if (LIST_EMPTY(&rtc_list)) {
		LIST_INSERT_HEAD(&rtc_list, newrtc, rtc_entries);
	} else {
		LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
			if (rtc->resolution > newrtc->resolution) {
				LIST_INSERT_BEFORE(rtc, newrtc, rtc_entries);
				break;
			} else if (LIST_NEXT(rtc, rtc_entries) == NULL) {
				LIST_INSERT_AFTER(rtc, newrtc, rtc_entries);
				break;
			}
		}
	}
	sx_xunlock(&rtc_list_lock);

	device_printf(clockdev, 
	    "registered as a time-of-day clock, resolution %d.%6.6ds\n",
	    newrtc->resolution / 1000000, newrtc->resolution % 1000000);
}

void
clock_register(device_t dev, long res)
{

	clock_register_flags(dev, res, 0);
}

void
clock_unregister(device_t clockdev)
{
	struct rtc_instance *rtc, *tmp;

	sx_xlock(&rtc_list_lock);
	LIST_FOREACH_SAFE(rtc, &rtc_list, rtc_entries, tmp) {
		if (rtc->clockdev == clockdev) {
			LIST_REMOVE(rtc, rtc_entries);
			break;
		}
	}
	sx_xunlock(&rtc_list_lock);
	if (rtc != NULL) {
		taskqueue_cancel_timeout(taskqueue_thread, &rtc->stask, NULL);
		taskqueue_drain_timeout(taskqueue_thread, &rtc->stask);
		free(rtc, M_DEVBUF);
	}
}

void
clock_schedule(device_t clockdev, u_int offsetns)
{
	struct rtc_instance *rtc;

	sx_xlock(&rtc_list_lock);
	LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
		if (rtc->clockdev == clockdev) {
			rtc->schedns = offsetns;
			break;
		}
	}
	sx_xunlock(&rtc_list_lock);
}

static int
read_clocks(struct timespec *ts, bool debug_read)
{
	struct rtc_instance *rtc;
	int error;

	error = ENXIO;
	sx_xlock(&rtc_list_lock);
	LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
		if ((error = CLOCK_GETTIME(rtc->clockdev, ts)) != 0)
			continue;
		if (ts->tv_sec < 0 || ts->tv_nsec < 0) {
			error = EINVAL;
			continue;
		}
		if (!(rtc->flags & CLOCKF_GETTIME_NO_ADJ)) {
			timespecadd(ts, &rtc->resadj, ts);
			ts->tv_sec += utc_offset();
		}
		if (!debug_read) {
			if (bootverbose)
				device_printf(rtc->clockdev,
				    "providing initial system time\n");
			break;
		}
	}
	sx_xunlock(&rtc_list_lock);
	return (error);
}

/*
 * Initialize the system time.  Must be called from a context which does not
 * restrict any locking or sleeping that clock drivers may need to do.
 *
 * First attempt to get the time from a registered realtime clock.  The clocks
 * are queried in order of resolution until one provides the time.  If no clock
 * can provide the current time, use the 'base' time provided by the caller, if
 * non-zero.  The 'base' time is potentially highly inaccurate, such as the last
 * known good value of the system clock, or even a filesystem last-updated
 * timestamp.  It is used to prevent system time from appearing to move
 * backwards in logs.
 */
void
inittodr(time_t base)
{
	struct timespec ts;
	int error;

	error = read_clocks(&ts, false);

	/*
	 * Do not report errors from each clock; it is expected that some clocks
	 * cannot provide results in some situations.  Only report problems when
	 * no clocks could provide the time.
	 */
	if (error != 0) {
		switch (error) {
		case ENXIO:
			printf("Warning: no time-of-day clock registered, ");
			break;
		case EINVAL:
			printf("Warning: bad time from time-of-day clock, ");
			break;
		default:
			printf("Error reading time-of-day clock (%d), ", error);
			break;
		}
		printf("system time will not be set accurately\n");
		ts.tv_sec  = (base > 0) ? base : -1;
		ts.tv_nsec = 0;
	}

	if (ts.tv_sec >= 0) {
		tc_setclock(&ts);
#ifdef FFCLOCK
		ffclock_reset_clock(&ts);
#endif
	}
}

/*
 * Write system time back to all registered clocks, unless disabled by admin.
 * This can be called from a context that restricts locking and/or sleeping; the
 * actual updating is done asynchronously on a task thread.
 */
void
resettodr(void)
{
	struct timespec now;
	struct rtc_instance *rtc;
	sbintime_t sbt;
	long waitns;

	if (disable_rtc_set)
		return;

	sx_xlock(&rtc_list_lock);
	LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
		if (rtc->schedns != 0) {
			getnanotime(&now);
			waitns = rtc->schedns - now.tv_nsec;
			if (waitns < 0)
				waitns += 1000000000;
			sbt = nstosbt(waitns);
		} else
			sbt = 0;
		taskqueue_enqueue_timeout_sbt(taskqueue_thread,
		    &rtc->stask, -sbt, 0, C_PREL(31));
	}
	sx_xunlock(&rtc_list_lock);
}

static int
sysctl_clock_do_io(SYSCTL_HANDLER_ARGS)
{
	struct timespec ts_discard;
	int error, value;

	value = 0;
	error = sysctl_handle_int(oidp, &value, 0, req);
	if (error != 0 || req->newptr == NULL)
		return (error);

	switch (value) {
	case CLOCK_DBG_READ:
		if (read_clocks(&ts_discard, true) == ENXIO)
			printf("No registered RTC clocks\n");
		break;
	case CLOCK_DBG_WRITE:
		resettodr();
		break;
	default:
                return (EINVAL);
	}

	return (0);
}