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("$FreeBSD$");
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 int error;
140
141 rtc = arg;
142 if (!(rtc->flags & CLOCKF_SETTIME_NO_TS)) {
143 getnanotime(&ts);
144 if (!(rtc->flags & CLOCKF_SETTIME_NO_ADJ)) {
145 ts.tv_sec -= utc_offset();
146 timespecadd(&ts, &rtc->resadj);
147 }
148 } else {
149 ts.tv_sec = 0;
150 ts.tv_nsec = 0;
151 }
152 error = CLOCK_SETTIME(rtc->clockdev, &ts);
153 if (error != 0 && bootverbose)
154 device_printf(rtc->clockdev, "CLOCK_SETTIME error %d\n", error);
155 }
156
157 static void
158 clock_dbgprint_hdr(device_t dev, int rw)
159 {
160 struct timespec now;
161
162 getnanotime(&now);
163 device_printf(dev, "%s at ", (rw & CLOCK_DBG_READ) ? "read " : "write");
164 clock_print_ts(&now, 9);
165 printf(": ");
166 }
167
168 void
169 clock_dbgprint_bcd(device_t dev, int rw, const struct bcd_clocktime *bct)
170 {
171
172 if (show_io & rw) {
173 clock_dbgprint_hdr(dev, rw);
174 clock_print_bcd(bct, 9);
175 printf("\n");
176 }
177 }
178
179 void
180 clock_dbgprint_ct(device_t dev, int rw, const struct clocktime *ct)
181 {
182
183 if (show_io & rw) {
184 clock_dbgprint_hdr(dev, rw);
185 clock_print_ct(ct, 9);
186 printf("\n");
187 }
188 }
189
190 void
191 clock_dbgprint_err(device_t dev, int rw, int err)
192 {
193
194 if (show_io & rw) {
195 clock_dbgprint_hdr(dev, rw);
196 printf("error = %d\n", err);
197 }
198 }
199
200 void
201 clock_dbgprint_ts(device_t dev, int rw, const struct timespec *ts)
202 {
203
204 if (show_io & rw) {
205 clock_dbgprint_hdr(dev, rw);
206 clock_print_ts(ts, 9);
207 printf("\n");
208 }
209 }
210
211 void
212 clock_register_flags(device_t clockdev, long resolution, int flags)
213 {
214 struct rtc_instance *rtc, *newrtc;
215
216 newrtc = malloc(sizeof(*newrtc), M_DEVBUF, M_WAITOK);
217 newrtc->clockdev = clockdev;
218 newrtc->resolution = (int)resolution;
219 newrtc->flags = flags;
220 newrtc->schedns = 0;
221 newrtc->resadj.tv_sec = newrtc->resolution / 2 / 1000000;
222 newrtc->resadj.tv_nsec = newrtc->resolution / 2 % 1000000 * 1000;
223 TIMEOUT_TASK_INIT(taskqueue_thread, &newrtc->stask, 0,
224 settime_task_func, newrtc);
225
226 sx_xlock(&rtc_list_lock);
227 if (LIST_EMPTY(&rtc_list)) {
228 LIST_INSERT_HEAD(&rtc_list, newrtc, rtc_entries);
229 } else {
230 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
231 if (rtc->resolution > newrtc->resolution) {
232 LIST_INSERT_BEFORE(rtc, newrtc, rtc_entries);
233 break;
234 } else if (LIST_NEXT(rtc, rtc_entries) == NULL) {
235 LIST_INSERT_AFTER(rtc, newrtc, rtc_entries);
236 break;
237 }
238 }
239 }
240 sx_xunlock(&rtc_list_lock);
241
242 device_printf(clockdev,
243 "registered as a time-of-day clock, resolution %d.%6.6ds\n",
244 newrtc->resolution / 1000000, newrtc->resolution % 1000000);
245 }
246
247 void
248 clock_register(device_t dev, long res)
249 {
250
251 clock_register_flags(dev, res, 0);
252 }
253
254 void
255 clock_unregister(device_t clockdev)
256 {
257 struct rtc_instance *rtc, *tmp;
258
259 sx_xlock(&rtc_list_lock);
260 LIST_FOREACH_SAFE(rtc, &rtc_list, rtc_entries, tmp) {
261 if (rtc->clockdev == clockdev) {
262 LIST_REMOVE(rtc, rtc_entries);
263 break;
264 }
265 }
266 sx_xunlock(&rtc_list_lock);
267 if (rtc != NULL) {
268 taskqueue_cancel_timeout(taskqueue_thread, &rtc->stask, NULL);
269 taskqueue_drain_timeout(taskqueue_thread, &rtc->stask);
270 free(rtc, M_DEVBUF);
271 }
272 }
273
274 void
275 clock_schedule(device_t clockdev, u_int offsetns)
276 {
277 struct rtc_instance *rtc;
278
279 sx_xlock(&rtc_list_lock);
280 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
281 if (rtc->clockdev == clockdev) {
282 rtc->schedns = offsetns;
283 break;
284 }
285 }
286 sx_xunlock(&rtc_list_lock);
287 }
288
289 static int
290 read_clocks(struct timespec *ts, bool debug_read)
291 {
292 struct rtc_instance *rtc;
293 int error;
294
295 error = ENXIO;
296 sx_xlock(&rtc_list_lock);
297 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
298 if ((error = CLOCK_GETTIME(rtc->clockdev, ts)) != 0)
299 continue;
300 if (ts->tv_sec < 0 || ts->tv_nsec < 0) {
301 error = EINVAL;
302 continue;
303 }
304 if (!(rtc->flags & CLOCKF_GETTIME_NO_ADJ)) {
305 timespecadd(ts, &rtc->resadj);
306 ts->tv_sec += utc_offset();
307 }
308 if (!debug_read) {
309 if (bootverbose)
310 device_printf(rtc->clockdev,
311 "providing initial system time\n");
312 break;
313 }
314 }
315 sx_xunlock(&rtc_list_lock);
316 return (error);
317 }
318
319 /*
320 * Initialize the system time. Must be called from a context which does not
321 * restrict any locking or sleeping that clock drivers may need to do.
322 *
323 * First attempt to get the time from a registered realtime clock. The clocks
324 * are queried in order of resolution until one provides the time. If no clock
325 * can provide the current time, use the 'base' time provided by the caller, if
326 * non-zero. The 'base' time is potentially highly inaccurate, such as the last
327 * known good value of the system clock, or even a filesystem last-updated
328 * timestamp. It is used to prevent system time from appearing to move
329 * backwards in logs.
330 */
331 void
332 inittodr(time_t base)
333 {
334 struct timespec ts;
335 int error;
336
337 error = read_clocks(&ts, false);
338
339 /*
340 * Do not report errors from each clock; it is expected that some clocks
341 * cannot provide results in some situations. Only report problems when
342 * no clocks could provide the time.
343 */
344 if (error != 0) {
345 switch (error) {
346 case ENXIO:
347 printf("Warning: no time-of-day clock registered, ");
348 break;
349 case EINVAL:
350 printf("Warning: bad time from time-of-day clock, ");
351 break;
352 default:
353 printf("Error reading time-of-day clock (%d), ", error);
354 break;
355 }
356 printf("system time will not be set accurately\n");
357 ts.tv_sec = (base > 0) ? base : -1;
358 ts.tv_nsec = 0;
359 }
360
361 if (ts.tv_sec >= 0) {
362 tc_setclock(&ts);
363 #ifdef FFCLOCK
364 ffclock_reset_clock(&ts);
365 #endif
366 }
367 }
368
369 /*
370 * Write system time back to all registered clocks, unless disabled by admin.
371 * This can be called from a context that restricts locking and/or sleeping; the
372 * actual updating is done asynchronously on a task thread.
373 */
374 void
375 resettodr(void)
376 {
377 struct timespec now;
378 struct rtc_instance *rtc;
379 sbintime_t sbt;
380 long waitns;
381
382 if (disable_rtc_set)
383 return;
384
385 sx_xlock(&rtc_list_lock);
386 LIST_FOREACH(rtc, &rtc_list, rtc_entries) {
387 if (rtc->schedns != 0) {
388 getnanotime(&now);
389 waitns = rtc->schedns - now.tv_nsec;
390 if (waitns < 0)
391 waitns += 1000000000;
392 sbt = nstosbt(waitns);
393 } else
394 sbt = 0;
395 taskqueue_enqueue_timeout_sbt(taskqueue_thread,
396 &rtc->stask, -sbt, 0, C_PREL(31));
397 }
398 sx_xunlock(&rtc_list_lock);
399 }
400
401 static int
402 sysctl_clock_do_io(SYSCTL_HANDLER_ARGS)
403 {
404 struct timespec ts_discard;
405 int error, value;
406
407 value = 0;
408 error = sysctl_handle_int(oidp, &value, 0, req);
409 if (error != 0 || req->newptr == NULL)
410 return (error);
411
412 switch (value) {
413 case CLOCK_DBG_READ:
414 if (read_clocks(&ts_discard, true) == ENXIO)
415 printf("No registered RTC clocks\n");
416 break;
417 case CLOCK_DBG_WRITE:
418 resettodr();
419 break;
420 default:
421 return (EINVAL);
422 }
423
424 return (0);
425 }
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