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: @(#)clock.c 8.2 (Berkeley) 1/12/94 43 * from: NetBSD: clock_subr.c,v 1.6 2001/07/07 17:04:02 thorpej Exp 44 * and 45 * from: src/sys/i386/isa/clock.c,v 1.176 2001/09/04 46 */ 47 48 /* 49 * Helpers for time-of-day clocks. This is useful for architectures that need 50 * support multiple models of such clocks, and generally serves to make the 51 * code more machine-independent. 52 * If the clock in question can also be used as a time counter, the driver 53 * needs to initiate this. 54 * This code is not yet used by all architectures. 55 */ 56 57 #include <sys/cdefs.h> 58 __FBSDID("$FreeBSD$"); 59 60 #include "opt_ffclock.h" 61 62 #include <sys/param.h> 63 #include <sys/systm.h> 64 #include <sys/kernel.h> 65 #include <sys/bus.h> 66 #include <sys/clock.h> 67 #include <sys/lock.h> 68 #include <sys/malloc.h> 69 #include <sys/sx.h> 70 #include <sys/sysctl.h> 71 #include <sys/taskqueue.h> 72 #ifdef FFCLOCK 73 #include <sys/timeffc.h> 74 #endif 75 #include <sys/timetc.h> 76 77 #include "clock_if.h" 78 79 /* XXX: should be kern. now, it's no longer machdep. */ 80 static int disable_rtc_set; 81 SYSCTL_INT(_machdep, OID_AUTO, disable_rtc_set, CTLFLAG_RW, &disable_rtc_set, 82 0, "Disallow adjusting time-of-day clock"); 83 84 /* 85 * An instance of a realtime clock. A list of these tracks all the registered 86 * clocks in the system. 87 * 88 * The resadj member is used to apply a "resolution adjustment" equal to half 89 * the clock's resolution, which is useful mainly on clocks with a whole-second 90 * resolution. Because the clock truncates the fractional part, adding half the 91 * resolution performs 4/5 rounding. The same adjustment is applied to the 92 * times returned from clock_gettime(), because the fraction returned will 93 * always be zero, but on average the actual fraction at the time of the call 94 * should be about .5. 95 */ 96 struct rtc_instance { 97 device_t clockdev; 98 int resolution; 99 int flags; 100 u_int schedns; 101 struct timespec resadj; 102 struct timeout_task 103 stask; 104 LIST_ENTRY(rtc_instance) 105 rtc_entries; 106 }; 107 108 /* 109 * Clocks are updated using a task running on taskqueue_thread. 110 */ 111 static void settime_task_func(void *arg, int pending); 112 113 /* 114 * Registered clocks are kept in a list which is sorted by resolution; the more 115 * accurate clocks get the first shot at providing the time. 116 */ 117 LIST_HEAD(rtc_listhead, rtc_instance); 118 static struct rtc_listhead rtc_list = LIST_HEAD_INITIALIZER(rtc_list); 119 static struct sx rtc_list_lock; 120 SX_SYSINIT(rtc_list_lock_init, &rtc_list_lock, "rtc list"); 121 122 /* 123 * On the task thread, invoke the clock_settime() method of the clock. Do so 124 * holding no locks, so that clock drivers are free to do whatever kind of 125 * locking or sleeping they need to. 126 */ 127 static void 128 settime_task_func(void *arg, int pending) 129 { 130 struct timespec ts; 131 struct rtc_instance *rtc; 132 133 rtc = arg; 134 if (!(rtc->flags & CLOCKF_SETTIME_NO_TS)) { 135 getnanotime(&ts); 136 if (!(rtc->flags & CLOCKF_SETTIME_NO_ADJ)) { 137 ts.tv_sec -= utc_offset(); 138 timespecadd(&ts, &rtc->resadj); 139 } 140 } else { 141 ts.tv_sec = 0; 142 ts.tv_nsec = 0; 143 } 144 CLOCK_SETTIME(rtc->clockdev, &ts); 145 } 146 147 void 148 clock_register_flags(device_t clockdev, long resolution, int flags) 149 { 150 struct rtc_instance *rtc, *newrtc; 151 152 newrtc = malloc(sizeof(*newrtc), M_DEVBUF, M_WAITOK); 153 newrtc->clockdev = clockdev; 154 newrtc->resolution = (int)resolution; 155 newrtc->flags = flags; 156 newrtc->schedns = 0; 157 newrtc->resadj.tv_sec = newrtc->resolution / 2 / 1000000; 158 newrtc->resadj.tv_nsec = newrtc->resolution / 2 % 1000000 * 1000; 159 TIMEOUT_TASK_INIT(taskqueue_thread, &newrtc->stask, 0, 160 settime_task_func, newrtc); 161 162 sx_xlock(&rtc_list_lock); 163 if (LIST_EMPTY(&rtc_list)) { 164 LIST_INSERT_HEAD(&rtc_list, newrtc, rtc_entries); 165 } else { 166 LIST_FOREACH(rtc, &rtc_list, rtc_entries) { 167 if (rtc->resolution > newrtc->resolution) { 168 LIST_INSERT_BEFORE(rtc, newrtc, rtc_entries); 169 break; 170 } else if (LIST_NEXT(rtc, rtc_entries) == NULL) { 171 LIST_INSERT_AFTER(rtc, newrtc, rtc_entries); 172 break; 173 } 174 } 175 } 176 sx_xunlock(&rtc_list_lock); 177 178 device_printf(clockdev, 179 "registered as a time-of-day clock, resolution %d.%6.6ds\n", 180 newrtc->resolution / 1000000, newrtc->resolution % 1000000); 181 } 182 183 void 184 clock_register(device_t dev, long res) 185 { 186 187 clock_register_flags(dev, res, 0); 188 } 189 190 void 191 clock_unregister(device_t clockdev) 192 { 193 struct rtc_instance *rtc, *tmp; 194 195 sx_xlock(&rtc_list_lock); 196 LIST_FOREACH_SAFE(rtc, &rtc_list, rtc_entries, tmp) { 197 if (rtc->clockdev == clockdev) { 198 LIST_REMOVE(rtc, rtc_entries); 199 break; 200 } 201 } 202 sx_xunlock(&rtc_list_lock); 203 if (rtc != NULL) { 204 taskqueue_cancel_timeout(taskqueue_thread, &rtc->stask, NULL); 205 taskqueue_drain_timeout(taskqueue_thread, &rtc->stask); 206 free(rtc, M_DEVBUF); 207 } 208 } 209 210 void 211 clock_schedule(device_t clockdev, u_int offsetns) 212 { 213 struct rtc_instance *rtc; 214 215 sx_xlock(&rtc_list_lock); 216 LIST_FOREACH(rtc, &rtc_list, rtc_entries) { 217 if (rtc->clockdev == clockdev) { 218 rtc->schedns = offsetns; 219 break; 220 } 221 } 222 sx_xunlock(&rtc_list_lock); 223 } 224 225 /* 226 * Initialize the system time. Must be called from a context which does not 227 * restrict any locking or sleeping that clock drivers may need to do. 228 * 229 * First attempt to get the time from a registered realtime clock. The clocks 230 * are queried in order of resolution until one provides the time. If no clock 231 * can provide the current time, use the 'base' time provided by the caller, if 232 * non-zero. The 'base' time is potentially highly inaccurate, such as the last 233 * known good value of the system clock, or even a filesystem last-updated 234 * timestamp. It is used to prevent system time from appearing to move 235 * backwards in logs. 236 */ 237 void 238 inittodr(time_t base) 239 { 240 struct timespec ts; 241 struct rtc_instance *rtc; 242 int error; 243 244 error = ENXIO; 245 sx_xlock(&rtc_list_lock); 246 LIST_FOREACH(rtc, &rtc_list, rtc_entries) { 247 if ((error = CLOCK_GETTIME(rtc->clockdev, &ts)) != 0) 248 continue; 249 if (ts.tv_sec < 0 || ts.tv_nsec < 0) { 250 error = EINVAL; 251 continue; 252 } 253 if (!(rtc->flags & CLOCKF_GETTIME_NO_ADJ)) { 254 timespecadd(&ts, &rtc->resadj); 255 ts.tv_sec += utc_offset(); 256 } 257 if (bootverbose) 258 device_printf(rtc->clockdev, 259 "providing initial system time\n"); 260 break; 261 } 262 sx_xunlock(&rtc_list_lock); 263 264 /* 265 * Do not report errors from each clock; it is expected that some clocks 266 * cannot provide results in some situations. Only report problems when 267 * no clocks could provide the time. 268 */ 269 if (error != 0) { 270 switch (error) { 271 case ENXIO: 272 printf("Warning: no time-of-day clock registered, "); 273 break; 274 case EINVAL: 275 printf("Warning: bad time from time-of-day clock, "); 276 break; 277 default: 278 printf("Error reading time-of-day clock (%d), ", error); 279 break; 280 } 281 printf("system time will not be set accurately\n"); 282 ts.tv_sec = (base > 0) ? base : -1; 283 ts.tv_nsec = 0; 284 } 285 286 if (ts.tv_sec >= 0) { 287 tc_setclock(&ts); 288 #ifdef FFCLOCK 289 ffclock_reset_clock(&ts); 290 #endif 291 } 292 } 293 294 /* 295 * Write system time back to all registered clocks, unless disabled by admin. 296 * This can be called from a context that restricts locking and/or sleeping; the 297 * actual updating is done asynchronously on a task thread. 298 */ 299 void 300 resettodr(void) 301 { 302 struct timespec now; 303 struct rtc_instance *rtc; 304 sbintime_t sbt; 305 long waitns; 306 307 if (disable_rtc_set) 308 return; 309 310 sx_xlock(&rtc_list_lock); 311 LIST_FOREACH(rtc, &rtc_list, rtc_entries) { 312 if (rtc->schedns != 0) { 313 getnanotime(&now); 314 waitns = rtc->schedns - now.tv_nsec; 315 if (waitns < 0) 316 waitns += 1000000000; 317 sbt = nstosbt(waitns); 318 } else 319 sbt = 0; 320 taskqueue_enqueue_timeout_sbt(taskqueue_thread, 321 &rtc->stask, -sbt, 0, C_PREL(31)); 322 } 323 sx_xunlock(&rtc_list_lock); 324 } 325