1 /*-
2 * Copyright (c) 1990 The Regents of the University of California.
3 * Copyright (c) 2008 The DragonFly Project.
4 * All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * William Jolitz and Don Ahn.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * from: @(#)clock.c 7.2 (Berkeley) 5/12/91
34 * $FreeBSD: src/sys/i386/isa/clock.c,v 1.149.2.6 2002/11/02 04:41:50 iwasaki Exp $
35 */
36
37 /*
38 * TSC cputimer.
39 */
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/kernel.h>
44 #include <sys/sysctl.h>
45 #include <sys/systimer.h>
46 #include <sys/globaldata.h>
47
48 #include <machine/clock.h>
49 #include <machine/cputypes.h>
50
51 static sysclock_t tsc_cputimer_count_mfence(void);
52 static sysclock_t tsc_cputimer_count_lfence(void);
53 static void tsc_cputimer_construct(struct cputimer *, sysclock_t);
54
55 static struct cputimer tsc_cputimer = {
56 .next = SLIST_ENTRY_INITIALIZER,
57 .name = "TSC",
58 .pri = CPUTIMER_PRI_TSC,
59 .type = CPUTIMER_TSC,
60 .count = NULL, /* determined later */
61 .fromhz = cputimer_default_fromhz,
62 .fromus = cputimer_default_fromus,
63 .construct = tsc_cputimer_construct,
64 .destruct = cputimer_default_destruct,
65 .freq = 0 /* determined later */
66 };
67
68 static struct cpucounter tsc_cpucounter = {
69 .freq = 0, /* determined later */
70 .count = NULL, /* determined later */
71 .flags = 0, /* adjusted later */
72 .prio = CPUCOUNTER_PRIO_TSC,
73 .type = CPUCOUNTER_TSC
74 };
75
76 static void
tsc_cputimer_construct(struct cputimer * timer,sysclock_t oldclock)77 tsc_cputimer_construct(struct cputimer *timer, sysclock_t oldclock)
78 {
79 timer->base = 0;
80 timer->base = oldclock - timer->count();
81 }
82
83 static __inline sysclock_t
tsc_cputimer_count(void)84 tsc_cputimer_count(void)
85 {
86 uint64_t tsc;
87
88 tsc = rdtsc();
89
90 return (tsc + tsc_cputimer.base);
91 }
92
93 static sysclock_t
tsc_cputimer_count_lfence(void)94 tsc_cputimer_count_lfence(void)
95 {
96 cpu_lfence();
97 return tsc_cputimer_count();
98 }
99
100 static sysclock_t
tsc_cputimer_count_mfence(void)101 tsc_cputimer_count_mfence(void)
102 {
103 cpu_mfence();
104 return tsc_cputimer_count();
105 }
106
107 static uint64_t
tsc_cpucounter_count_lfence(void)108 tsc_cpucounter_count_lfence(void)
109 {
110 cpu_lfence();
111 return (rdtsc());
112 }
113
114 static uint64_t
tsc_cpucounter_count_mfence(void)115 tsc_cpucounter_count_mfence(void)
116 {
117 cpu_mfence();
118 return (rdtsc());
119 }
120
121 static void
tsc_cputimer_register(void)122 tsc_cputimer_register(void)
123 {
124 uint64_t freq;
125 int enable = 1;
126
127 if (!tsc_mpsync) {
128 #ifndef _KERNEL_VIRTUAL
129 if (tsc_invariant) {
130 /* Per-cpu cpucounter still works. */
131 goto regcnt;
132 }
133 #endif
134 return;
135 }
136
137 TUNABLE_INT_FETCH("hw.tsc_cputimer_enable", &enable);
138 if (!enable)
139 return;
140
141 /*
142 * NOTE: We no longer shift the tsc to limit the reported
143 * frequency. We use the actual tsc frequency as-is.
144 */
145 freq = tsc_frequency;
146 tsc_cputimer.freq = freq;
147
148 kprintf("TSC: cputimer freq %ju\n", (uintmax_t)freq);
149
150 if (cpu_vendor_id == CPU_VENDOR_INTEL)
151 tsc_cputimer.count = tsc_cputimer_count_lfence;
152 else
153 tsc_cputimer.count = tsc_cputimer_count_mfence; /* safe bet */
154
155 cputimer_register(&tsc_cputimer);
156 cputimer_select(&tsc_cputimer, 0);
157
158 tsc_cpucounter.flags |= CPUCOUNTER_FLAG_MPSYNC;
159 #ifndef _KERNEL_VIRTUAL
160 regcnt:
161 #endif
162 tsc_cpucounter.freq = tsc_frequency;
163 if (cpu_vendor_id == CPU_VENDOR_INTEL) {
164 tsc_cpucounter.count =
165 tsc_cpucounter_count_lfence;
166 } else {
167 tsc_cpucounter.count =
168 tsc_cpucounter_count_mfence; /* safe bet */
169 }
170 cpucounter_register(&tsc_cpucounter);
171 }
172 SYSINIT(tsc_cputimer_reg, SI_BOOT2_POST_SMP, SI_ORDER_FIRST,
173 tsc_cputimer_register, NULL);
174