2 * Copyright (c) 1998-2003 Poul-Henning Kamp
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
30 #include "opt_clock.h"
32 #include <sys/param.h>
35 #include <sys/malloc.h>
36 #include <sys/systm.h>
37 #include <sys/sysctl.h>
39 #include <sys/timetc.h>
40 #include <sys/kernel.h>
41 #include <sys/power.h>
43 #include <machine/clock.h>
44 #include <machine/md_var.h>
45 #include <machine/specialreg.h>
47 #include "cpufreq_if.h"
53 static eventhandler_tag tsc_levels_tag, tsc_pre_tag, tsc_post_tag;
55 SYSCTL_INT(_kern_timecounter, OID_AUTO, invariant_tsc, CTLFLAG_RDTUN,
56 &tsc_is_invariant, 0, "Indicates whether the TSC is P-state invariant");
57 TUNABLE_INT("kern.timecounter.invariant_tsc", &tsc_is_invariant);
61 SYSCTL_INT(_kern_timecounter, OID_AUTO, smp_tsc, CTLFLAG_RDTUN, &smp_tsc, 0,
62 "Indicates whether the TSC is safe to use in SMP mode");
63 TUNABLE_INT("kern.timecounter.smp_tsc", &smp_tsc);
66 static void tsc_freq_changed(void *arg, const struct cf_level *level,
68 static void tsc_freq_changing(void *arg, const struct cf_level *level,
70 static unsigned tsc_get_timecount(struct timecounter *tc);
71 static void tsc_levels_changed(void *arg, int unit);
73 static struct timecounter tsc_timecounter = {
74 tsc_get_timecount, /* get_timecount */
76 ~0u, /* counter_mask */
79 800, /* quality (adjusted in code) */
87 if (cpu_feature & CPUID_TSC)
96 printf("Calibrating TSC clock ... ");
102 tsc_freq = tscval[1] - tscval[0];
104 printf("TSC clock: %ju Hz\n", (intmax_t)tsc_freq);
107 * Inform CPU accounting about our boot-time clock rate. Once the
108 * system is finished booting, we will get the real max clock rate
109 * via tsc_freq_max(). This also will be updated if someone loads
110 * a cpufreq driver after boot that discovers a new max frequency.
112 set_cputicker(rdtsc, tsc_freq, 1);
114 /* Register to find out about changes in CPU frequency. */
115 tsc_pre_tag = EVENTHANDLER_REGISTER(cpufreq_pre_change,
116 tsc_freq_changing, NULL, EVENTHANDLER_PRI_FIRST);
117 tsc_post_tag = EVENTHANDLER_REGISTER(cpufreq_post_change,
118 tsc_freq_changed, NULL, EVENTHANDLER_PRI_FIRST);
119 tsc_levels_tag = EVENTHANDLER_REGISTER(cpufreq_levels_changed,
120 tsc_levels_changed, NULL, EVENTHANDLER_PRI_ANY);
127 * We can not use the TSC if we support APM. Precise timekeeping
128 * on an APM'ed machine is at best a fools pursuit, since
129 * any and all of the time spent in various SMM code can't
130 * be reliably accounted for. Reading the RTC is your only
131 * source of reliable time info. The i8254 loses too, of course,
132 * but we need to have some kind of time...
133 * We don't know at this point whether APM is going to be used
134 * or not, nor when it might be activated. Play it safe.
136 if (power_pm_get_type() == POWER_PM_TYPE_APM) {
137 tsc_timecounter.tc_quality = -1000;
139 printf("TSC timecounter disabled: APM enabled.\n");
144 * We can not use the TSC in SMP mode unless the TSCs on all CPUs
145 * are somehow synchronized. Some hardware configurations do
146 * this, but we have no way of determining whether this is the
147 * case, so we do not use the TSC in multi-processor systems
148 * unless the user indicated (by setting kern.timecounter.smp_tsc
149 * to 1) that he believes that his TSCs are synchronized.
151 if (mp_ncpus > 1 && !smp_tsc)
152 tsc_timecounter.tc_quality = -100;
155 if (tsc_present && tsc_freq != 0 && !tsc_is_broken) {
156 tsc_timecounter.tc_frequency = tsc_freq;
157 tc_init(&tsc_timecounter);
162 * When cpufreq levels change, find out about the (new) max frequency. We
163 * use this to update CPU accounting in case it got a lower estimate at boot.
166 tsc_levels_changed(void *arg, int unit)
169 struct cf_level *levels;
173 if (tsc_is_invariant)
176 /* Only use values from the first CPU, assuming all are equal. */
180 /* Find the appropriate cpufreq device instance. */
181 cf_dev = devclass_get_device(devclass_find("cpufreq"), unit);
182 if (cf_dev == NULL) {
183 printf("tsc_levels_changed() called but no cpufreq device?\n");
187 /* Get settings from the device and find the max frequency. */
189 levels = malloc(count * sizeof(*levels), M_TEMP, M_NOWAIT);
192 error = CPUFREQ_LEVELS(cf_dev, levels, &count);
193 if (error == 0 && count != 0) {
194 max_freq = (uint64_t)levels[0].total_set.freq * 1000000;
195 set_cputicker(rdtsc, max_freq, 1);
197 printf("tsc_levels_changed: no max freq found\n");
198 free(levels, M_TEMP);
202 * If the TSC timecounter is in use, veto the pending change. It may be
203 * possible in the future to handle a dynamically-changing timecounter rate.
206 tsc_freq_changing(void *arg, const struct cf_level *level, int *status)
209 if (*status != 0 || timecounter != &tsc_timecounter ||
213 printf("timecounter TSC must not be in use when "
214 "changing frequencies; change denied\n");
218 /* Update TSC freq with the value indicated by the caller. */
220 tsc_freq_changed(void *arg, const struct cf_level *level, int status)
223 * If there was an error during the transition or
224 * TSC is P-state invariant, don't do anything.
226 if (status != 0 || tsc_is_invariant)
229 /* Total setting for this level gives the new frequency in MHz. */
230 tsc_freq = (uint64_t)level->total_set.freq * 1000000;
231 tsc_timecounter.tc_frequency = tsc_freq;
235 sysctl_machdep_tsc_freq(SYSCTL_HANDLER_ARGS)
240 if (tsc_timecounter.tc_frequency == 0)
243 error = sysctl_handle_quad(oidp, &freq, 0, req);
244 if (error == 0 && req->newptr != NULL) {
246 tsc_timecounter.tc_frequency = tsc_freq;
251 SYSCTL_PROC(_machdep, OID_AUTO, tsc_freq, CTLTYPE_QUAD | CTLFLAG_RW,
252 0, sizeof(u_int), sysctl_machdep_tsc_freq, "QU", "");
255 tsc_get_timecount(struct timecounter *tc)