1 /* $NetBSD: acpi_timer.c,v 1.21 2011/08/08 11:27:44 jmcneill 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 1.21 2011/08/08 11:27:44 jmcneill 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 42 static int acpitimer_test(void); 43 44 static struct timecounter acpi_timecounter = { 45 acpitimer_read_safe, 46 0, 47 0x00ffffff, 48 PM_TIMER_FREQUENCY, 49 "ACPI-Safe", 50 900, 51 NULL, 52 NULL, 53 }; 54 55 int 56 acpitimer_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 87 int 88 acpitimer_detach(void) 89 { 90 91 return tc_detach(&acpi_timecounter); 92 } 93 94 u_int 95 acpitimer_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 */ 108 u_int 109 acpitimer_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 } 126 127 uint32_t 128 acpitimer_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 142 143 static int 144 acpitimer_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