subr_rtc.c revision 331722
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: stable/11/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 77static int show_io; 78SYSCTL_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 81static int sysctl_clock_do_io(SYSCTL_HANDLER_ARGS); 82SYSCTL_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. */ 87static int disable_rtc_set; 88SYSCTL_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 */ 103struct 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 */ 118static 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 */ 124LIST_HEAD(rtc_listhead, rtc_instance); 125static struct rtc_listhead rtc_list = LIST_HEAD_INITIALIZER(rtc_list); 126static struct sx rtc_list_lock; 127SX_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 */ 134static void 135settime_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 154static void 155clock_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 165void 166clock_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 176void 177clock_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 187void 188clock_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 197void 198clock_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 208void 209clock_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 244void 245clock_register(device_t dev, long res) 246{ 247 248 clock_register_flags(dev, res, 0); 249} 250 251void 252clock_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 271void 272clock_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 286static int 287read_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 */ 328void 329inittodr(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 */ 371void 372resettodr(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 398static int 399sysctl_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} 423