1/* $NetBSD: acpi_timer.c,v 1.22 2013/12/27 18:51:44 christos Exp $ */
2
3/*-
4 * Copyright (c) 2006 Matthias Drochner <drochner@NetBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__KERNEL_RCSID(0, "$NetBSD: acpi_timer.c,v 1.22 2013/12/27 18:51:44 christos Exp $");
31
32#include <sys/types.h>
33#include <sys/systm.h>
34#include <sys/time.h>
35#include <sys/timetc.h>
36
37#include <dev/acpi/acpivar.h>
38#include <dev/acpi/acpi_timer.h>
39
40#include <machine/acpi_machdep.h>
41
42static int acpitimer_test(void);
43
44static struct timecounter acpi_timecounter = {
45 acpitimer_read_safe,
46 0,
47 0x00ffffff,
48 ACPI_PM_TIMER_FREQUENCY,
49 "ACPI-Safe",
50 900,
51 NULL,
52 NULL,
53};
54
55int
56acpitimer_init(struct acpi_softc *sc)
57{
58 ACPI_STATUS rv;
59 uint32_t bits;
60 int i, j;
61
62 rv = AcpiGetTimerResolution(&bits);
63
64 if (ACPI_FAILURE(rv))
65 return -1;
66
67 if (bits == 32)
68 acpi_timecounter.tc_counter_mask = 0xffffffff;
69
70 for (i = j = 0; i < 10; i++)
71 j += acpitimer_test();
72
73 if (j >= 10) {
74 acpi_timecounter.tc_name = "ACPI-Fast";
75 acpi_timecounter.tc_get_timecount = acpitimer_read_fast;
76 acpi_timecounter.tc_quality = 1000;
77 }
78
79 tc_init(&acpi_timecounter);
80
81 aprint_debug_dev(sc->sc_dev, "%s %d-bit timer\n",
82 acpi_timecounter.tc_name, bits);
83
84 return 0;
85}
86
87int
88acpitimer_detach(void)
89{
90
91 return tc_detach(&acpi_timecounter);
92}
93
94u_int
95acpitimer_read_fast(struct timecounter *tc)
96{
97 uint32_t t;
98
99 (void)AcpiGetTimer(&t);
100
101 return t;
102}
103
104/*
105 * Some chipsets (PIIX4 variants) do not latch correctly;
106 * there is a chance that a transition is hit.
107 */
108u_int
109acpitimer_read_safe(struct timecounter *tc)
110{
111 uint32_t t1, t2, t3;
112
113 (void)AcpiGetTimer(&t2);
114 (void)AcpiGetTimer(&t3);
115
116 do {
117 t1 = t2;
118 t2 = t3;
119
120 (void)AcpiGetTimer(&t3);
121
122 } while ((t1 > t2) || (t2 > t3));
123
124 return t2;
125}
126
127uint32_t
128acpitimer_delta(uint32_t end, uint32_t start)
129{
130 const u_int mask = acpi_timecounter.tc_counter_mask;
131 uint32_t delta;
132
133 if (end >= start)
134 delta = end - start;
135 else
136 delta = ((mask - start) + end + 1) & mask;
137
138 return delta;
139}
140
141#define N 2000
142
143static int
144acpitimer_test(void)
145{
146 uint32_t last, this, delta;
147 int minl, maxl, n;
148
149 minl = 10000000;
150 maxl = 0;
151
152 acpi_md_OsDisableInterrupt();
153
154 (void)AcpiGetTimer(&last);
155
156 for (n = 0; n < N; n++) {
157
158 (void)AcpiGetTimer(&this);
159
160 delta = acpitimer_delta(this, last);
161
162 if (delta > maxl)
163 maxl = delta;
164 else if (delta < minl)
165 minl = delta;
166
167 last = this;
168 }
169
170 acpi_md_OsEnableInterrupt();
171
172 if (maxl - minl > 2 )
173 n = 0;
174 else if (minl < 0 || maxl == 0)
175 n = 0;
176 else
177 n = 1;
178
179 return n;
180}
181