2 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * WARNING! THE SYSTIMER MODULE DOES NOT OPERATE OR DISPATCH WITH THE
37 * MP LOCK HELD. ALL CODE USING THIS MODULE MUST BE MP-SAFE.
39 * This code implements a fine-grained per-cpu system timer which is
40 * ultimately based on a hardware timer. The hardware timer abstraction
41 * is sufficiently disconnected from this code to support both per-cpu
42 * hardware timers or a single system-wide hardware timer.
44 * WARNING! During early boot if a new system timer is selected, existing
45 * timeouts will not be effected and will thus occur slower or faster.
46 * periodic timers will be adjusted at the next periodic load.
48 * Notes on machine-dependant code (in arch/arch/systimer.c)
50 * cputimer_intr_reload() Reload the one-shot (per-cpu basis)
53 #include <sys/param.h>
54 #include <sys/kernel.h>
55 #include <sys/systm.h>
56 #include <sys/thread.h>
57 #include <sys/globaldata.h>
58 #include <sys/systimer.h>
59 #include <sys/thread2.h>
62 * Execute ready systimers. Called directly from the platform-specific
63 * one-shot timer clock interrupt (e.g. clkintr()) or via an IPI. May
64 * be called simultaniously on multiple cpus and always operations on
65 * the current cpu's queue. Systimer functions are responsible for calling
66 * hardclock, statclock, and other finely-timed routines.
69 systimer_intr(sysclock_t *timep, int in_ipi, struct intrframe *frame)
71 globaldata_t gd = mycpu;
72 sysclock_t time = *timep;
80 while ((info = TAILQ_FIRST(&gd->gd_systimerq)) != NULL) {
82 * If we haven't reached the requested time, tell the cputimer
83 * how much is left and break out.
85 if ((int)(info->time - time) > 0) {
86 cputimer_intr_reload(info->time - time);
91 * Dequeue and execute, detect a loss of the systimer. Note
92 * that the in-progress systimer pointer can only be used to
93 * detect a loss of the systimer, it is only useful within
94 * this code sequence and becomes stale otherwise.
96 info->flags &= ~SYSTF_ONQUEUE;
97 TAILQ_REMOVE(info->queue, info, node);
98 gd->gd_systimer_inprog = info;
100 info->func(info, in_ipi, frame);
104 * The caller may deleted or even re-queue the systimer itself
105 * with a delete/add sequence. If the caller does not mess with
106 * the systimer we will requeue the periodic interval automatically.
108 * If this is a non-queued periodic interrupt, do not allow multiple
109 * events to build up (used for things like the callout timer to
110 * prevent premature timeouts due to long interrupt disablements,
111 * BIOS 8254 glitching, and so forth). However, we still want to
112 * keep things synchronized between cpus for efficient handling of
113 * the timer interrupt so jump in multiples of the periodic rate.
115 if (gd->gd_systimer_inprog == info && info->periodic) {
116 if (info->which != sys_cputimer) {
117 info->periodic = sys_cputimer->fromhz(info->freq);
118 info->which = sys_cputimer;
120 info->time += info->periodic;
121 if ((info->flags & SYSTF_NONQUEUED) &&
122 (int)(info->time - time) <= 0
124 info->time += ((time - info->time + info->periodic - 1) /
125 info->periodic) * info->periodic;
129 gd->gd_systimer_inprog = NULL;
136 systimer_intr_enable(void)
138 cputimer_intr_enable();
145 systimer_add(systimer_t info)
147 struct globaldata *gd = mycpu;
149 KKASSERT((info->flags & SYSTF_ONQUEUE) == 0);
151 if (info->gd == gd) {
154 scan1 = TAILQ_FIRST(&gd->gd_systimerq);
155 if (scan1 == NULL || (int)(scan1->time - info->time) > 0) {
156 cputimer_intr_reload(info->time - sys_cputimer->count());
157 TAILQ_INSERT_HEAD(&gd->gd_systimerq, info, node);
159 scan2 = TAILQ_LAST(&gd->gd_systimerq, systimerq);
162 TAILQ_INSERT_TAIL(&gd->gd_systimerq, info, node);
165 if ((int)(scan1->time - info->time) > 0) {
166 TAILQ_INSERT_BEFORE(scan1, info, node);
169 if ((int)(scan2->time - info->time) <= 0) {
170 TAILQ_INSERT_AFTER(&gd->gd_systimerq, scan2, info, node);
173 scan1 = TAILQ_NEXT(scan1, node);
174 scan2 = TAILQ_PREV(scan2, systimerq, node);
177 info->flags = (info->flags | SYSTF_ONQUEUE) & ~SYSTF_IPIRUNNING;
178 info->queue = &gd->gd_systimerq;
180 KKASSERT((info->flags & SYSTF_IPIRUNNING) == 0);
181 info->flags |= SYSTF_IPIRUNNING;
182 lwkt_send_ipiq(info->gd, (ipifunc1_t)systimer_add, info);
190 * Delete a system timer. Only the owning cpu can delete a timer.
195 systimer_del(systimer_t info)
197 struct globaldata *gd = info->gd;
199 KKASSERT(gd == mycpu && (info->flags & SYSTF_IPIRUNNING) == 0);
203 if (info->flags & SYSTF_ONQUEUE) {
204 TAILQ_REMOVE(info->queue, info, node);
205 info->flags &= ~SYSTF_ONQUEUE;
209 * Deal with dispatch races by clearing the in-progress systimer
210 * pointer. Only a direct pointer comparison can be used, the
211 * actual contents of the structure gd_systimer_inprog points to,
212 * if not equal to info, may be stale.
214 if (gd->gd_systimer_inprog == info)
215 gd->gd_systimer_inprog = NULL;
221 * systimer_init_periodic()
223 * Initialize a periodic timer at the specified frequency and add
224 * it to the system. The frequency is uncompensated and approximate.
226 * Try to synchronize multi registrations of the same or similar
227 * frequencies so the hardware interrupt is able to dispatch several
228 * at together by adjusting the phase of the initial interrupt. This
229 * helps SMP. Note that we are not attempting to synchronize to
230 * the realtime clock.
233 systimer_init_periodic(systimer_t info, systimer_func_t func, void *data,
236 sysclock_t base_count;
238 bzero(info, sizeof(struct systimer));
239 info->periodic = sys_cputimer->fromhz(hz);
240 base_count = sys_cputimer->count();
241 base_count = base_count - (base_count % info->periodic);
242 info->time = base_count + info->periodic;
246 info->which = sys_cputimer;
252 systimer_init_periodic_nq(systimer_t info, systimer_func_t func, void *data,
255 sysclock_t base_count;
257 bzero(info, sizeof(struct systimer));
258 info->periodic = sys_cputimer->fromhz(hz);
259 base_count = sys_cputimer->count();
260 base_count = base_count - (base_count % info->periodic);
261 info->time = base_count + info->periodic;
265 info->which = sys_cputimer;
267 info->flags |= SYSTF_NONQUEUED;
272 * Adjust the periodic interval for a periodic timer which is already
273 * running. The current timeout is not effected.
276 systimer_adjust_periodic(systimer_t info, int hz)
279 info->periodic = sys_cputimer->fromhz(hz);
281 info->which = sys_cputimer;
286 * systimer_init_oneshot()
288 * Initialize a periodic timer at the specified frequency and add
289 * it to the system. The frequency is uncompensated and approximate.
292 systimer_init_oneshot(systimer_t info, systimer_func_t func, void *data, int us)
294 bzero(info, sizeof(struct systimer));
295 info->time = sys_cputimer->count() + sys_cputimer->fromus(us);
298 info->which = sys_cputimer;