xref: /freebsd/sys/x86/x86/tsc.c (revision 10b9d77bf1ccf2f3affafa6261692cb92cf7e992)
1 /*-
2  * Copyright (c) 1998-2003 Poul-Henning Kamp
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
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.
13  *
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
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include "opt_clock.h"
31 
32 #include <sys/param.h>
33 #include <sys/bus.h>
34 #include <sys/cpu.h>
35 #include <sys/malloc.h>
36 #include <sys/systm.h>
37 #include <sys/sysctl.h>
38 #include <sys/time.h>
39 #include <sys/timetc.h>
40 #include <sys/kernel.h>
41 #include <sys/power.h>
42 #include <sys/smp.h>
43 #include <machine/clock.h>
44 #include <machine/cputypes.h>
45 #include <machine/md_var.h>
46 #include <machine/specialreg.h>
47 
48 #include "cpufreq_if.h"
49 
50 uint64_t	tsc_freq;
51 int		tsc_is_broken;
52 int		tsc_is_invariant;
53 int		tsc_present;
54 static eventhandler_tag tsc_levels_tag, tsc_pre_tag, tsc_post_tag;
55 
56 SYSCTL_INT(_kern_timecounter, OID_AUTO, invariant_tsc, CTLFLAG_RDTUN,
57     &tsc_is_invariant, 0, "Indicates whether the TSC is P-state invariant");
58 TUNABLE_INT("kern.timecounter.invariant_tsc", &tsc_is_invariant);
59 
60 #ifdef SMP
61 static int	smp_tsc;
62 SYSCTL_INT(_kern_timecounter, OID_AUTO, smp_tsc, CTLFLAG_RDTUN, &smp_tsc, 0,
63     "Indicates whether the TSC is safe to use in SMP mode");
64 TUNABLE_INT("kern.timecounter.smp_tsc", &smp_tsc);
65 #endif
66 
67 static void tsc_freq_changed(void *arg, const struct cf_level *level,
68     int status);
69 static void tsc_freq_changing(void *arg, const struct cf_level *level,
70     int *status);
71 static	unsigned tsc_get_timecount(struct timecounter *tc);
72 static void tsc_levels_changed(void *arg, int unit);
73 
74 static struct timecounter tsc_timecounter = {
75 	tsc_get_timecount,	/* get_timecount */
76 	0,			/* no poll_pps */
77 	~0u,			/* counter_mask */
78 	0,			/* frequency */
79 	"TSC",			/* name */
80 	800,			/* quality (adjusted in code) */
81 };
82 
83 void
84 init_TSC(void)
85 {
86 	u_int64_t tscval[2];
87 
88 	if (cpu_feature & CPUID_TSC)
89 		tsc_present = 1;
90 	else
91 		tsc_present = 0;
92 
93 	if (!tsc_present)
94 		return;
95 
96 	if (bootverbose)
97 	        printf("Calibrating TSC clock ... ");
98 
99 	tscval[0] = rdtsc();
100 	DELAY(1000000);
101 	tscval[1] = rdtsc();
102 
103 	tsc_freq = tscval[1] - tscval[0];
104 	if (bootverbose)
105 		printf("TSC clock: %ju Hz\n", (intmax_t)tsc_freq);
106 
107 	switch (cpu_vendor_id) {
108 	case CPU_VENDOR_AMD:
109 		if ((amd_pminfo & AMDPM_TSC_INVARIANT) ||
110 		    CPUID_TO_FAMILY(cpu_id) >= 0x10)
111 			tsc_is_invariant = 1;
112 		break;
113 	case CPU_VENDOR_INTEL:
114 		if ((amd_pminfo & AMDPM_TSC_INVARIANT) ||
115 		    (CPUID_TO_FAMILY(cpu_id) == 0x6 &&
116 		    CPUID_TO_MODEL(cpu_id) >= 0xe) ||
117 		    (CPUID_TO_FAMILY(cpu_id) == 0xf &&
118 		    CPUID_TO_MODEL(cpu_id) >= 0x3))
119 			tsc_is_invariant = 1;
120 		break;
121 	case CPU_VENDOR_CENTAUR:
122 		if (CPUID_TO_FAMILY(cpu_id) == 0x6 &&
123 		    CPUID_TO_MODEL(cpu_id) >= 0xf &&
124 		    (rdmsr(0x1203) & 0x100000000ULL) == 0)
125 			tsc_is_invariant = 1;
126 		break;
127 	}
128 
129 	/*
130 	 * Inform CPU accounting about our boot-time clock rate.  This will
131 	 * be updated if someone loads a cpufreq driver after boot that
132 	 * discovers a new max frequency.
133 	 */
134 	set_cputicker(rdtsc, tsc_freq, 1);
135 
136 	if (tsc_is_invariant)
137 		return;
138 
139 	/* Register to find out about changes in CPU frequency. */
140 	tsc_pre_tag = EVENTHANDLER_REGISTER(cpufreq_pre_change,
141 	    tsc_freq_changing, NULL, EVENTHANDLER_PRI_FIRST);
142 	tsc_post_tag = EVENTHANDLER_REGISTER(cpufreq_post_change,
143 	    tsc_freq_changed, NULL, EVENTHANDLER_PRI_FIRST);
144 	tsc_levels_tag = EVENTHANDLER_REGISTER(cpufreq_levels_changed,
145 	    tsc_levels_changed, NULL, EVENTHANDLER_PRI_ANY);
146 }
147 
148 void
149 init_TSC_tc(void)
150 {
151 
152 	if (!tsc_present)
153 		return;
154 
155 	/*
156 	 * We can not use the TSC if we support APM.  Precise timekeeping
157 	 * on an APM'ed machine is at best a fools pursuit, since
158 	 * any and all of the time spent in various SMM code can't
159 	 * be reliably accounted for.  Reading the RTC is your only
160 	 * source of reliable time info.  The i8254 loses too, of course,
161 	 * but we need to have some kind of time...
162 	 * We don't know at this point whether APM is going to be used
163 	 * or not, nor when it might be activated.  Play it safe.
164 	 */
165 	if (power_pm_get_type() == POWER_PM_TYPE_APM) {
166 		tsc_timecounter.tc_quality = -1000;
167 		if (bootverbose)
168 			printf("TSC timecounter disabled: APM enabled.\n");
169 	}
170 
171 #ifdef SMP
172 	/*
173 	 * We can not use the TSC in SMP mode unless the TSCs on all CPUs
174 	 * are somehow synchronized.  Some hardware configurations do
175 	 * this, but we have no way of determining whether this is the
176 	 * case, so we do not use the TSC in multi-processor systems
177 	 * unless the user indicated (by setting kern.timecounter.smp_tsc
178 	 * to 1) that he believes that his TSCs are synchronized.
179 	 */
180 	if (mp_ncpus > 1 && !smp_tsc)
181 		tsc_timecounter.tc_quality = -100;
182 #endif
183 
184 	if (tsc_freq != 0 && !tsc_is_broken) {
185 		tsc_timecounter.tc_frequency = tsc_freq;
186 		tc_init(&tsc_timecounter);
187 	}
188 }
189 
190 /*
191  * When cpufreq levels change, find out about the (new) max frequency.  We
192  * use this to update CPU accounting in case it got a lower estimate at boot.
193  */
194 static void
195 tsc_levels_changed(void *arg, int unit)
196 {
197 	device_t cf_dev;
198 	struct cf_level *levels;
199 	int count, error;
200 	uint64_t max_freq;
201 
202 	/* Only use values from the first CPU, assuming all are equal. */
203 	if (unit != 0)
204 		return;
205 
206 	/* Find the appropriate cpufreq device instance. */
207 	cf_dev = devclass_get_device(devclass_find("cpufreq"), unit);
208 	if (cf_dev == NULL) {
209 		printf("tsc_levels_changed() called but no cpufreq device?\n");
210 		return;
211 	}
212 
213 	/* Get settings from the device and find the max frequency. */
214 	count = 64;
215 	levels = malloc(count * sizeof(*levels), M_TEMP, M_NOWAIT);
216 	if (levels == NULL)
217 		return;
218 	error = CPUFREQ_LEVELS(cf_dev, levels, &count);
219 	if (error == 0 && count != 0) {
220 		max_freq = (uint64_t)levels[0].total_set.freq * 1000000;
221 		set_cputicker(rdtsc, max_freq, 1);
222 	} else
223 		printf("tsc_levels_changed: no max freq found\n");
224 	free(levels, M_TEMP);
225 }
226 
227 /*
228  * If the TSC timecounter is in use, veto the pending change.  It may be
229  * possible in the future to handle a dynamically-changing timecounter rate.
230  */
231 static void
232 tsc_freq_changing(void *arg, const struct cf_level *level, int *status)
233 {
234 
235 	if (*status != 0 || timecounter != &tsc_timecounter)
236 		return;
237 
238 	printf("timecounter TSC must not be in use when "
239 	    "changing frequencies; change denied\n");
240 	*status = EBUSY;
241 }
242 
243 /* Update TSC freq with the value indicated by the caller. */
244 static void
245 tsc_freq_changed(void *arg, const struct cf_level *level, int status)
246 {
247 
248 	/* If there was an error during the transition, don't do anything. */
249 	if (status != 0)
250 		return;
251 
252 	/* Total setting for this level gives the new frequency in MHz. */
253 	tsc_freq = (uint64_t)level->total_set.freq * 1000000;
254 	tsc_timecounter.tc_frequency = tsc_freq;
255 }
256 
257 static int
258 sysctl_machdep_tsc_freq(SYSCTL_HANDLER_ARGS)
259 {
260 	int error;
261 	uint64_t freq;
262 
263 	if (tsc_timecounter.tc_frequency == 0)
264 		return (EOPNOTSUPP);
265 	freq = tsc_freq;
266 	error = sysctl_handle_64(oidp, &freq, 0, req);
267 	if (error == 0 && req->newptr != NULL) {
268 		tsc_freq = freq;
269 		tsc_timecounter.tc_frequency = tsc_freq;
270 	}
271 	return (error);
272 }
273 
274 SYSCTL_PROC(_machdep, OID_AUTO, tsc_freq, CTLTYPE_U64 | CTLFLAG_RW,
275     0, 0, sysctl_machdep_tsc_freq, "QU", "");
276 
277 static unsigned
278 tsc_get_timecount(struct timecounter *tc)
279 {
280 	return (rdtsc());
281 }
282