FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_rtc.c
1 /*-
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
6 * All rights reserved.
7 *
8 * This code is derived from software contributed to Berkeley by
9 * the Systems Programming Group of the University of Utah Computer
10 * Science Department.
11 *
12 * Portions of this software were developed by Julien Ridoux at the University
13 * of Melbourne under sponsorship from the FreeBSD Foundation.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
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 * 4. 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.
26 *
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
37 * SUCH DAMAGE.
38 *
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
42 * and
43 * from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04
44 */
45
46 /*
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.
53 */
54
55 #include <sys/cdefs.h>
56 __FBSDID("$FreeBSD: releng/11.2/sys/kern/subr_rtc.c 331722 2018-03-29 02:50:57Z eadler $");
57
58 #include "opt_ffclock.h"
59
60 #include <sys/param.h>
61 #include <sys/systm.h>
62 #include <sys/kernel.h>
63 #include <sys/bus.h>
64 #include <sys/clock.h>
65 #include <sys/lock.h>
66 #include <sys/malloc.h>
67 #include <sys/sx.h>
68 #include <sys/sysctl.h>
69 #include <sys/taskqueue.h>
70 #ifdef FFCLOCK
71 #include <sys/timeffc.h>
72 #endif
73 #include <sys/timetc.h>
74
75 #include "clock_if.h"
76
77 static int show_io;
78 SYSCTL_INT(_debug, OID_AUTO, clock_show_io, CTLFLAG_RWTUN, &show_io, 0,
79 "Enable debug printing of RTC clock I/O; 1=reads, 2=writes, 3=both.");
80
81 static int sysctl_clock_do_io(SYSCTL_HANDLER_ARGS);
82 SYSCTL_PROC(_debug, OID_AUTO, clock_do_io, CTLTYPE_INT | CTLFLAG_RW,
83 0, 0, sysctl_clock_do_io, "I",
84 "Trigger one-time IO on RTC clocks; 1=read (and discard), 2=write");
85
86 /* XXX: should be kern. now, it's no longer machdep. */
87 static int disable_rtc_set;
88 SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set, CTLFLAG_RW, &disable_rtc_set,
89 0, "Disallow adjusting time-of-day clock");
90
91 /*
92 * An instance of a realtime clock. A list of these tracks all the registered
93 * clocks in the system.
94 *
95 * The resadj member is used to apply a "resolution adjustment" equal to half
96 * the clock's resolution, which is useful mainly on clocks with a whole-second
97 * resolution. Because the clock truncates the fractional part, adding half the
98 * resolution performs 4/5 rounding. The same adjustment is applied to the
99 * times returned from clock_gettime(), because the fraction returned will
100 * always be zero, but on average the actual fraction at the time of the call
101 * should be about .5.
102 */
103 struct rtc_instance {
104 device_t clockdev;
105 int resolution;
106 int flags;
107 u_int schedns;
108 struct timespec resadj;
109 struct timeout_task
110 stask;
111 LIST_ENTRY(rtc_instance)
112 rtc_entries;
113 };
114
115 /*
116 * Clocks are updated using a task running on taskqueue_thread.
117 */
118 static void settime_task_func(void *arg, int pending);
119
120 /*
121 * Registered clocks are kept in a list which is sorted by resolution; the more
122 * accurate clocks get the first shot at providing the time.
123 */
124 LIST_HEAD(rtc_listhead, rtc_instance);
125 static struct rtc_listhead rtc_list = LIST_HEAD_INITIALIZER(rtc_list);
126 static struct sx rtc_list_lock;
127 SX_SYSINIT(rtc_list_lock_init, &rtc_list_lock, "rtc list");
128
129 /*
130 * On the task thread, invoke the clock_settime() method of the clock. Do so
131 * holding no locks, so that clock drivers are free to do whatever kind of
132 * locking or sleeping they need to.
133 */
134 static void
135 settime_task_func(void *arg, int pending)
136 {
137 struct timespec ts;
138 struct rtc_instance *rtc;
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);
146 }
147 } else {
148 ts.tv_sec = 0;
149 ts.tv_nsec = 0;
150 }
151 CLOCK_SETTIME(rtc->clockdev, &ts);
152 }
153
154 static void
155 clock_dbgprint_hdr(device_t dev, int rw)
156 {
157 struct timespec now;
158
159 getnanotime(&now);
160 device_printf(dev, "%s at ", (rw & CLOCK_DBG_READ) ? "read " : "write");
161 clock_print_ts(&now, 9);
162 printf(": ");
163 }
164
165 void
166 clock_dbgprint_bcd(device_t dev, int rw, const struct bcd_clocktime *bct)
167 {
168
169 if (show_io & rw) {
170 clock_dbgprint_hdr(dev, rw);
171 clock_print_bcd(bct, 9);
172 printf("\n");
173 }
174 }
175
176 void
177 clock_dbgprint_ct(device_t dev, int rw, const struct clocktime *ct)
178 {
179
180 if (show_io & rw) {
181 clock_dbgprint_hdr(dev, rw);
182 clock_print_ct(ct, 9);
183 printf("\n");
184 }
185 }
186
187 void
188 clock_dbgprint_err(device_t dev, int rw, int err)
189 {
190
191 if (show_io & rw) {
192 clock_dbgprint_hdr(dev, rw);
193 printf("error = %d\n", err);
194 }
195 }
196
197 void
198 clock_dbgprint_ts(device_t dev, int rw, const struct timespec *ts)
199 {
200
201 if (show_io & rw) {
202 clock_dbgprint_hdr(dev, rw);
203 clock_print_ts(ts, 9);
204 printf("\n");
205 }
206 }
207
208 void
209 clock_register_flags(device_t clockdev, long resolution, int flags)
210 {
211 struct rtc_instance *rtc, *newrtc;
212
213 newrtc = malloc(sizeof(*newrtc), M_DEVBUF, M_WAITOK);
214 newrtc->clockdev = clockdev;
215 newrtc->resolution = (int)resolution;
216 newrtc->flags = flags;
217 newrtc->schedns = 0;
218 newrtc->resadj.tv_sec = newrtc->resolution / 2 / 1000000;
219 newrtc->resadj.tv_nsec = newrtc->resolution / 2 % 1000000 * 1000;
220 TIMEOUT_TASK_INIT(taskqueue_thread, &newrtc->stask, 0,
221 settime_task_func, newrtc);
222
223 sx_xlock(&rtc_list_lock);
224 if (LIST_EMPTY(&rtc_list)) {
225 LIST_INSERT_HEAD(&rtc_list, newrtc, rtc_entries);
226 } else {
227 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
228 if (rtc->resolution > newrtc->resolution) {
229 LIST_INSERT_BEFORE(rtc, newrtc, rtc_entries);
230 break;
231 } else if (LIST_NEXT(rtc, rtc_entries) == NULL) {
232 LIST_INSERT_AFTER(rtc, newrtc, rtc_entries);
233 break;
234 }
235 }
236 }
237 sx_xunlock(&rtc_list_lock);
238
239 device_printf(clockdev,
240 "registered as a time-of-day clock, resolution %d.%6.6ds\n",
241 newrtc->resolution / 1000000, newrtc->resolution % 1000000);
242 }
243
244 void
245 clock_register(device_t dev, long res)
246 {
247
248 clock_register_flags(dev, res, 0);
249 }
250
251 void
252 clock_unregister(device_t clockdev)
253 {
254 struct rtc_instance *rtc, *tmp;
255
256 sx_xlock(&rtc_list_lock);
257 LIST_FOREACH_SAFE(rtc, &rtc_list, rtc_entries, tmp) {
258 if (rtc->clockdev == clockdev) {
259 LIST_REMOVE(rtc, rtc_entries);
260 break;
261 }
262 }
263 sx_xunlock(&rtc_list_lock);
264 if (rtc != NULL) {
265 taskqueue_cancel_timeout(taskqueue_thread, &rtc->stask, NULL);
266 taskqueue_drain_timeout(taskqueue_thread, &rtc->stask);
267 free(rtc, M_DEVBUF);
268 }
269 }
270
271 void
272 clock_schedule(device_t clockdev, u_int offsetns)
273 {
274 struct rtc_instance *rtc;
275
276 sx_xlock(&rtc_list_lock);
277 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
278 if (rtc->clockdev == clockdev) {
279 rtc->schedns = offsetns;
280 break;
281 }
282 }
283 sx_xunlock(&rtc_list_lock);
284 }
285
286 static int
287 read_clocks(struct timespec *ts, bool debug_read)
288 {
289 struct rtc_instance *rtc;
290 int error;
291
292 error = ENXIO;
293 sx_xlock(&rtc_list_lock);
294 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
295 if ((error = CLOCK_GETTIME(rtc->clockdev, ts)) != 0)
296 continue;
297 if (ts->tv_sec < 0 || ts->tv_nsec < 0) {
298 error = EINVAL;
299 continue;
300 }
301 if (!(rtc->flags & CLOCKF_GETTIME_NO_ADJ)) {
302 timespecadd(ts, &rtc->resadj);
303 ts->tv_sec += utc_offset();
304 }
305 if (!debug_read) {
306 if (bootverbose)
307 device_printf(rtc->clockdev,
308 "providing initial system time\n");
309 break;
310 }
311 }
312 sx_xunlock(&rtc_list_lock);
313 return (error);
314 }
315
316 /*
317 * Initialize the system time. Must be called from a context which does not
318 * restrict any locking or sleeping that clock drivers may need to do.
319 *
320 * First attempt to get the time from a registered realtime clock. The clocks
321 * are queried in order of resolution until one provides the time. If no clock
322 * can provide the current time, use the 'base' time provided by the caller, if
323 * non-zero. The 'base' time is potentially highly inaccurate, such as the last
324 * known good value of the system clock, or even a filesystem last-updated
325 * timestamp. It is used to prevent system time from appearing to move
326 * backwards in logs.
327 */
328 void
329 inittodr(time_t base)
330 {
331 struct timespec ts;
332 int error;
333
334 error = read_clocks(&ts, false);
335
336 /*
337 * Do not report errors from each clock; it is expected that some clocks
338 * cannot provide results in some situations. Only report problems when
339 * no clocks could provide the time.
340 */
341 if (error != 0) {
342 switch (error) {
343 case ENXIO:
344 printf("Warning: no time-of-day clock registered, ");
345 break;
346 case EINVAL:
347 printf("Warning: bad time from time-of-day clock, ");
348 break;
349 default:
350 printf("Error reading time-of-day clock (%d), ", error);
351 break;
352 }
353 printf("system time will not be set accurately\n");
354 ts.tv_sec = (base > 0) ? base : -1;
355 ts.tv_nsec = 0;
356 }
357
358 if (ts.tv_sec >= 0) {
359 tc_setclock(&ts);
360 #ifdef FFCLOCK
361 ffclock_reset_clock(&ts);
362 #endif
363 }
364 }
365
366 /*
367 * Write system time back to all registered clocks, unless disabled by admin.
368 * This can be called from a context that restricts locking and/or sleeping; the
369 * actual updating is done asynchronously on a task thread.
370 */
371 void
372 resettodr(void)
373 {
374 struct timespec now;
375 struct rtc_instance *rtc;
376 sbintime_t sbt;
377 long waitns;
378
379 if (disable_rtc_set)
380 return;
381
382 sx_xlock(&rtc_list_lock);
383 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
384 if (rtc->schedns != 0) {
385 getnanotime(&now);
386 waitns = rtc->schedns - now.tv_nsec;
387 if (waitns < 0)
388 waitns += 1000000000;
389 sbt = nstosbt(waitns);
390 } else
391 sbt = 0;
392 taskqueue_enqueue_timeout_sbt(taskqueue_thread,
393 &rtc->stask, -sbt, 0, C_PREL(31));
394 }
395 sx_xunlock(&rtc_list_lock);
396 }
397
398 static int
399 sysctl_clock_do_io(SYSCTL_HANDLER_ARGS)
400 {
401 struct timespec ts_discard;
402 int error, value;
403
404 value = 0;
405 error = sysctl_handle_int(oidp, &value, 0, req);
406 if (error != 0 || req->newptr == NULL)
407 return (error);
408
409 switch (value) {
410 case CLOCK_DBG_READ:
411 if (read_clocks(&ts_discard, true) == ENXIO)
412 printf("No registered RTC clocks\n");
413 break;
414 case CLOCK_DBG_WRITE:
415 resettodr();
416 break;
417 default:
418 return (EINVAL);
419 }
420
421 return (0);
422 }
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