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
settime_task_func(void * arg,int pending)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
clock_dbgprint_hdr(device_t dev,int rw)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
clock_dbgprint_bcd(device_t dev,int rw,const struct bcd_clocktime * bct)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
clock_dbgprint_ct(device_t dev,int rw,const struct clocktime * ct)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
clock_dbgprint_err(device_t dev,int rw,int err)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
clock_dbgprint_ts(device_t dev,int rw,const struct timespec * ts)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
clock_register_flags(device_t clockdev,long resolution,int flags)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
clock_register(device_t dev,long res)247 clock_register(device_t dev, long res)
248 {
249
250 clock_register_flags(dev, res, 0);
251 }
252
253 void
clock_unregister(device_t clockdev)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
clock_schedule(device_t clockdev,u_int offsetns)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
read_clocks(struct timespec * ts,bool debug_read)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
inittodr(time_t base)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
resettodr(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
sysctl_clock_do_io(SYSCTL_HANDLER_ARGS)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