1 /* $NetBSD: acpi_timer.c,v 1.27 2021/07/25 01:43:08 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 1.27 2021/07/25 01:43:08 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 #if (!ACPI_REDUCED_HARDWARE) 43 static int acpitimer_test(void); 44 45 static struct timecounter acpi_timecounter = { 46 .tc_get_timecount = acpitimer_read_safe, 47 .tc_counter_mask = 0x00ffffff, 48 .tc_frequency = ACPI_PM_TIMER_FREQUENCY, 49 .tc_name = "ACPI-Safe", 50 .tc_quality = 900, 51 }; 52 53 static bool 54 acpitimer_supported(void) 55 { 56 return AcpiGbl_FADT.PmTimerLength != 0; 57 } 58 #endif 59 60 int 61 acpitimer_init(struct acpi_softc *sc) 62 { 63 #if (!ACPI_REDUCED_HARDWARE) 64 ACPI_TABLE_WAET *waet; 65 ACPI_STATUS rv; 66 uint32_t bits; 67 int i, j; 68 69 if (!acpitimer_supported()) 70 return -1; 71 72 rv = AcpiGetTimerResolution(&bits); 73 74 if (ACPI_FAILURE(rv)) 75 return -1; 76 77 if (bits == 32) 78 acpi_timecounter.tc_counter_mask = 0xffffffff; 79 80 for (i = j = 0; i < 10; i++) 81 j += acpitimer_test(); 82 83 rv = AcpiGetTable(ACPI_SIG_WAET, 0, (ACPI_TABLE_HEADER **)&waet); 84 if (ACPI_SUCCESS(rv)) { 85 /* 86 * Windows ACPI Emulated Devices Table (WAET) has a hint 87 * to let the OS know that a single read of the PM timer 88 * provides a reliable value. 89 */ 90 if ((waet->Flags & ACPI_WAET_TIMER_ONE_READ) != 0) { 91 j += 10; 92 } 93 } 94 95 if (j >= 10) { 96 acpi_timecounter.tc_name = "ACPI-Fast"; 97 acpi_timecounter.tc_get_timecount = acpitimer_read_fast; 98 acpi_timecounter.tc_quality = 1000; 99 } 100 101 tc_init(&acpi_timecounter); 102 103 aprint_debug_dev(sc->sc_dev, "%s %d-bit timer\n", 104 acpi_timecounter.tc_name, bits); 105 106 return 0; 107 #else 108 return -1; 109 #endif 110 } 111 112 int 113 acpitimer_detach(void) 114 { 115 #if (!ACPI_REDUCED_HARDWARE) 116 if (!acpitimer_supported()) 117 return -1; 118 119 return tc_detach(&acpi_timecounter); 120 #else 121 return -1; 122 #endif 123 } 124 125 #if (!ACPI_REDUCED_HARDWARE) 126 u_int 127 acpitimer_read_fast(struct timecounter *tc) 128 { 129 uint32_t t; 130 131 (void)AcpiGetTimer(&t); 132 133 return t; 134 } 135 136 /* 137 * Some chipsets (PIIX4 variants) do not latch correctly; 138 * there is a chance that a transition is hit. 139 */ 140 u_int 141 acpitimer_read_safe(struct timecounter *tc) 142 { 143 uint32_t t1, t2, t3; 144 145 (void)AcpiGetTimer(&t2); 146 (void)AcpiGetTimer(&t3); 147 148 do { 149 t1 = t2; 150 t2 = t3; 151 152 (void)AcpiGetTimer(&t3); 153 154 } while ((t1 > t2) || (t2 > t3)); 155 156 return t2; 157 } 158 159 uint32_t 160 acpitimer_delta(uint32_t end, uint32_t start) 161 { 162 const u_int mask = acpi_timecounter.tc_counter_mask; 163 uint32_t delta; 164 165 if (end >= start) 166 delta = end - start; 167 else 168 delta = ((mask - start) + end + 1) & mask; 169 170 return delta; 171 } 172 173 #define N 2000 174 175 static int 176 acpitimer_test(void) 177 { 178 uint32_t last, this, delta; 179 int minl, maxl, n; 180 181 minl = 10000000; 182 maxl = 0; 183 184 acpi_md_OsDisableInterrupt(); 185 186 (void)AcpiGetTimer(&last); 187 188 for (n = 0; n < N; n++) { 189 190 (void)AcpiGetTimer(&this); 191 192 delta = acpitimer_delta(this, last); 193 194 if (delta > maxl) 195 maxl = delta; 196 else if (delta < minl) 197 minl = delta; 198 199 last = this; 200 } 201 202 acpi_md_OsEnableInterrupt(); 203 204 if (maxl - minl > 2 ) 205 n = 0; 206 else if (minl < 0 || maxl == 0) 207 n = 0; 208 else 209 n = 1; 210 211 return n; 212 } 213 #endif 214