xref: /freebsd/sys/kern/subr_rtc.c (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
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
8  * All rights reserved.
9  *
10  * This code is derived from software contributed to Berkeley by
11  * the Systems Programming Group of the University of Utah Computer
12  * Science Department.
13  *
14  * Portions of this software were developed by Julien Ridoux at the University
15  * of Melbourne under sponsorship from the FreeBSD Foundation.
16  *
17  * Redistribution and use in source and binary forms, with or without
18  * modification, are permitted provided that the following conditions
19  * are met:
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.
28  *
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
39  * SUCH DAMAGE.
40  *
41  *	from: Utah $Hdr: clock.c 1.18 91/01/21$
42  *	from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp
43  *	and
44  *	from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
45  */
46 
47 /*
48  * Helpers for time-of-day clocks. This is useful for architectures that need
49  * support multiple models of such clocks, and generally serves to make the
50  * code more machine-independent.
51  * If the clock in question can also be used as a time counter, the driver
52  * needs to initiate this.
53  * This code is not yet used by all architectures.
54  */
55 
56 #include <sys/cdefs.h>
57 #include "opt_ffclock.h"
58 
59 #include <sys/param.h>
60 #include <sys/systm.h>
61 #include <sys/kernel.h>
62 #include <sys/bus.h>
63 #include <sys/clock.h>
64 #include <sys/lock.h>
65 #include <sys/malloc.h>
66 #include <sys/sx.h>
67 #include <sys/sysctl.h>
68 #include <sys/taskqueue.h>
69 #ifdef FFCLOCK
70 #include <sys/timeffc.h>
71 #endif
72 #include <sys/timetc.h>
73 
74 #include "clock_if.h"
75 
76 static int show_io;
77 SYSCTL_INT(_debug, OID_AUTO, clock_show_io, CTLFLAG_RWTUN, &show_io, 0,
78     "Enable debug printing of RTC clock I/O; 1=reads, 2=writes, 3=both.");
79 
80 static int sysctl_clock_do_io(SYSCTL_HANDLER_ARGS);
81 SYSCTL_PROC(_debug, OID_AUTO, clock_do_io,
82     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 0, sysctl_clock_do_io, "I",
83     "Trigger one-time IO on RTC clocks; 1=read (and discard), 2=write");
84 
85 /* XXX: should be kern. now, it's no longer machdep.  */
86 static int disable_rtc_set;
87 SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set, CTLFLAG_RW, &disable_rtc_set,
88     0, "Disallow adjusting time-of-day clock");
89 
90 /*
91  * An instance of a realtime clock.  A list of these tracks all the registered
92  * clocks in the system.
93  *
94  * The resadj member is used to apply a "resolution adjustment" equal to half
95  * the clock's resolution, which is useful mainly on clocks with a whole-second
96  * resolution.  Because the clock truncates the fractional part, adding half the
97  * resolution performs 4/5 rounding.  The same adjustment is applied to the
98  * times returned from clock_gettime(), because the fraction returned will
99  * always be zero, but on average the actual fraction at the time of the call
100  * should be about .5.
101  */
102 struct rtc_instance {
103 	device_t	clockdev;
104 	int		resolution;
105 	int		flags;
106 	u_int		schedns;
107 	struct timespec resadj;
108 	struct timeout_task
109 			stask;
110 	LIST_ENTRY(rtc_instance)
111 			rtc_entries;
112 };
113 
114 /*
115  * Clocks are updated using a task running on taskqueue_thread.
116  */
117 static void settime_task_func(void *arg, int pending);
118 
119 /*
120  * Registered clocks are kept in a list which is sorted by resolution; the more
121  * accurate clocks get the first shot at providing the time.
122  */
123 LIST_HEAD(rtc_listhead, rtc_instance);
124 static struct rtc_listhead rtc_list = LIST_HEAD_INITIALIZER(rtc_list);
125 static struct sx rtc_list_lock;
126 SX_SYSINIT(rtc_list_lock_init, &rtc_list_lock, "rtc list");
127 
128 /*
129  * On the task thread, invoke the clock_settime() method of the clock.  Do so
130  * holding no locks, so that clock drivers are free to do whatever kind of
131  * locking or sleeping they need to.
132  */
133 static void
134 settime_task_func(void *arg, int pending)
135 {
136 	struct timespec ts;
137 	struct rtc_instance *rtc;
138 	int error;
139 
140 	rtc = arg;
141 	if (!(rtc->flags & CLOCKF_SETTIME_NO_TS)) {
142 		getnanotime(&ts);
143 		if (!(rtc->flags & CLOCKF_SETTIME_NO_ADJ)) {
144 			ts.tv_sec -= utc_offset();
145 			timespecadd(&ts, &rtc->resadj, &ts);
146 		}
147 	} else {
148 		ts.tv_sec  = 0;
149 		ts.tv_nsec = 0;
150 	}
151 	error = CLOCK_SETTIME(rtc->clockdev, &ts);
152 	if (error != 0 && bootverbose)
153 		device_printf(rtc->clockdev, "CLOCK_SETTIME error %d\n", error);
154 }
155 
156 static void
157 clock_dbgprint_hdr(device_t dev, int rw)
158 {
159 	struct timespec now;
160 
161 	getnanotime(&now);
162 	device_printf(dev, "%s at ", (rw & CLOCK_DBG_READ) ? "read " : "write");
163 	clock_print_ts(&now, 9);
164 	printf(": ");
165 }
166 
167 void
168 clock_dbgprint_bcd(device_t dev, int rw, const struct bcd_clocktime *bct)
169 {
170 
171 	if (show_io & rw) {
172 		clock_dbgprint_hdr(dev, rw);
173 		clock_print_bcd(bct, 9);
174 		printf("\n");
175 	}
176 }
177 
178 void
179 clock_dbgprint_ct(device_t dev, int rw, const struct clocktime *ct)
180 {
181 
182 	if (show_io & rw) {
183 		clock_dbgprint_hdr(dev, rw);
184 		clock_print_ct(ct, 9);
185 		printf("\n");
186 	}
187 }
188 
189 void
190 clock_dbgprint_err(device_t dev, int rw, int err)
191 {
192 
193 	if (show_io & rw) {
194 		clock_dbgprint_hdr(dev, rw);
195 		printf("error = %d\n", err);
196 	}
197 }
198 
199 void
200 clock_dbgprint_ts(device_t dev, int rw, const struct timespec *ts)
201 {
202 
203 	if (show_io & rw) {
204 		clock_dbgprint_hdr(dev, rw);
205 		clock_print_ts(ts, 9);
206 		printf("\n");
207 	}
208 }
209 
210 void
211 clock_register_flags(device_t clockdev, long resolution, int flags)
212 {
213 	struct rtc_instance *rtc, *newrtc;
214 
215 	newrtc = malloc(sizeof(*newrtc), M_DEVBUF, M_WAITOK);
216 	newrtc->clockdev = clockdev;
217 	newrtc->resolution = (int)resolution;
218 	newrtc->flags = flags;
219 	newrtc->schedns = 0;
220 	newrtc->resadj.tv_sec  = newrtc->resolution / 2 / 1000000;
221 	newrtc->resadj.tv_nsec = newrtc->resolution / 2 % 1000000 * 1000;
222 	TIMEOUT_TASK_INIT(taskqueue_thread, &newrtc->stask, 0,
223 		    settime_task_func, newrtc);
224 
225 	sx_xlock(&rtc_list_lock);
226 	if (LIST_EMPTY(&rtc_list)) {
227 		LIST_INSERT_HEAD(&rtc_list, newrtc, rtc_entries);
228 	} else {
229 		LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
230 			if (rtc->resolution > newrtc->resolution) {
231 				LIST_INSERT_BEFORE(rtc, newrtc, rtc_entries);
232 				break;
233 			} else if (LIST_NEXT(rtc, rtc_entries) == NULL) {
234 				LIST_INSERT_AFTER(rtc, newrtc, rtc_entries);
235 				break;
236 			}
237 		}
238 	}
239 	sx_xunlock(&rtc_list_lock);
240 
241 	device_printf(clockdev,
242 	    "registered as a time-of-day clock, resolution %d.%6.6ds\n",
243 	    newrtc->resolution / 1000000, newrtc->resolution % 1000000);
244 }
245 
246 void
247 clock_register(device_t dev, long res)
248 {
249 
250 	clock_register_flags(dev, res, 0);
251 }
252 
253 void
254 clock_unregister(device_t clockdev)
255 {
256 	struct rtc_instance *rtc, *tmp;
257 
258 	sx_xlock(&rtc_list_lock);
259 	LIST_FOREACH_SAFE(rtc, &rtc_list, rtc_entries, tmp) {
260 		if (rtc->clockdev == clockdev) {
261 			LIST_REMOVE(rtc, rtc_entries);
262 			break;
263 		}
264 	}
265 	sx_xunlock(&rtc_list_lock);
266 	if (rtc != NULL) {
267 		taskqueue_cancel_timeout(taskqueue_thread, &rtc->stask, NULL);
268 		taskqueue_drain_timeout(taskqueue_thread, &rtc->stask);
269 		free(rtc, M_DEVBUF);
270 	}
271 }
272 
273 void
274 clock_schedule(device_t clockdev, u_int offsetns)
275 {
276 	struct rtc_instance *rtc;
277 
278 	sx_xlock(&rtc_list_lock);
279 	LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
280 		if (rtc->clockdev == clockdev) {
281 			rtc->schedns = offsetns;
282 			break;
283 		}
284 	}
285 	sx_xunlock(&rtc_list_lock);
286 }
287 
288 static int
289 read_clocks(struct timespec *ts, bool debug_read)
290 {
291 	struct rtc_instance *rtc;
292 	int error;
293 
294 	error = ENXIO;
295 	sx_xlock(&rtc_list_lock);
296 	LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
297 		if ((error = CLOCK_GETTIME(rtc->clockdev, ts)) != 0)
298 			continue;
299 		if (ts->tv_sec < 0 || ts->tv_nsec < 0) {
300 			error = EINVAL;
301 			continue;
302 		}
303 		if (!(rtc->flags & CLOCKF_GETTIME_NO_ADJ)) {
304 			timespecadd(ts, &rtc->resadj, ts);
305 			ts->tv_sec += utc_offset();
306 		}
307 		if (!debug_read) {
308 			if (bootverbose)
309 				device_printf(rtc->clockdev,
310 				    "providing initial system time\n");
311 			break;
312 		}
313 	}
314 	sx_xunlock(&rtc_list_lock);
315 	return (error);
316 }
317 
318 /*
319  * Initialize the system time.  Must be called from a context which does not
320  * restrict any locking or sleeping that clock drivers may need to do.
321  *
322  * First attempt to get the time from a registered realtime clock.  The clocks
323  * are queried in order of resolution until one provides the time.  If no clock
324  * can provide the current time, use the 'base' time provided by the caller, if
325  * non-zero.  The 'base' time is potentially highly inaccurate, such as the last
326  * known good value of the system clock, or even a filesystem last-updated
327  * timestamp.  It is used to prevent system time from appearing to move
328  * backwards in logs.
329  */
330 void
331 inittodr(time_t base)
332 {
333 	struct timespec ts;
334 	int error;
335 
336 	error = read_clocks(&ts, false);
337 
338 	/*
339 	 * Do not report errors from each clock; it is expected that some clocks
340 	 * cannot provide results in some situations.  Only report problems when
341 	 * no clocks could provide the time.
342 	 */
343 	if (error != 0) {
344 		switch (error) {
345 		case ENXIO:
346 			printf("Warning: no time-of-day clock registered, ");
347 			break;
348 		case EINVAL:
349 			printf("Warning: bad time from time-of-day clock, ");
350 			break;
351 		default:
352 			printf("Error reading time-of-day clock (%d), ", error);
353 			break;
354 		}
355 		printf("system time will not be set accurately\n");
356 		ts.tv_sec  = (base > 0) ? base : -1;
357 		ts.tv_nsec = 0;
358 	}
359 
360 	if (ts.tv_sec >= 0) {
361 		tc_setclock(&ts);
362 #ifdef FFCLOCK
363 		ffclock_reset_clock(&ts);
364 #endif
365 	}
366 }
367 
368 /*
369  * Write system time back to all registered clocks, unless disabled by admin.
370  * This can be called from a context that restricts locking and/or sleeping; the
371  * actual updating is done asynchronously on a task thread.
372  */
373 void
374 resettodr(void)
375 {
376 	struct timespec now;
377 	struct rtc_instance *rtc;
378 	sbintime_t sbt;
379 	long waitns;
380 
381 	if (disable_rtc_set)
382 		return;
383 
384 	sx_xlock(&rtc_list_lock);
385 	LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
386 		if (rtc->schedns != 0) {
387 			getnanotime(&now);
388 			waitns = rtc->schedns - now.tv_nsec;
389 			if (waitns < 0)
390 				waitns += 1000000000;
391 			sbt = nstosbt(waitns);
392 		} else
393 			sbt = 0;
394 		taskqueue_enqueue_timeout_sbt(taskqueue_thread,
395 		    &rtc->stask, -sbt, 0, C_PREL(31));
396 	}
397 	sx_xunlock(&rtc_list_lock);
398 }
399 
400 static int
401 sysctl_clock_do_io(SYSCTL_HANDLER_ARGS)
402 {
403 	struct timespec ts_discard;
404 	int error, value;
405 
406 	value = 0;
407 	error = sysctl_handle_int(oidp, &value, 0, req);
408 	if (error != 0 || req->newptr == NULL)
409 		return (error);
410 
411 	switch (value) {
412 	case CLOCK_DBG_READ:
413 		if (read_clocks(&ts_discard, true) == ENXIO)
414 			printf("No registered RTC clocks\n");
415 		break;
416 	case CLOCK_DBG_WRITE:
417 		resettodr();
418 		break;
419 	default:
420                 return (EINVAL);
421 	}
422 
423 	return (0);
424 }
425