1 /* $NetBSD: acpi_timer.c,v 1.26 2020/05/29 12:30:41 rin 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 1.26 2020/05/29 12:30:41 rin 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_STATUS rv; 65 uint32_t bits; 66 int i, j; 67 68 if (!acpitimer_supported()) 69 return -1; 70 71 rv = AcpiGetTimerResolution(&bits); 72 73 if (ACPI_FAILURE(rv)) 74 return -1; 75 76 if (bits == 32) 77 acpi_timecounter.tc_counter_mask = 0xffffffff; 78 79 for (i = j = 0; i < 10; i++) 80 j += acpitimer_test(); 81 82 if (j >= 10) { 83 acpi_timecounter.tc_name = "ACPI-Fast"; 84 acpi_timecounter.tc_get_timecount = acpitimer_read_fast; 85 acpi_timecounter.tc_quality = 1000; 86 } 87 88 tc_init(&acpi_timecounter); 89 90 aprint_debug_dev(sc->sc_dev, "%s %d-bit timer\n", 91 acpi_timecounter.tc_name, bits); 92 93 return 0; 94 #else 95 return -1; 96 #endif 97 } 98 99 int 100 acpitimer_detach(void) 101 { 102 #if (!ACPI_REDUCED_HARDWARE) 103 if (!acpitimer_supported()) 104 return -1; 105 106 return tc_detach(&acpi_timecounter); 107 #else 108 return -1; 109 #endif 110 } 111 112 #if (!ACPI_REDUCED_HARDWARE) 113 u_int 114 acpitimer_read_fast(struct timecounter *tc) 115 { 116 uint32_t t; 117 118 (void)AcpiGetTimer(&t); 119 120 return t; 121 } 122 123 /* 124 * Some chipsets (PIIX4 variants) do not latch correctly; 125 * there is a chance that a transition is hit. 126 */ 127 u_int 128 acpitimer_read_safe(struct timecounter *tc) 129 { 130 uint32_t t1, t2, t3; 131 132 (void)AcpiGetTimer(&t2); 133 (void)AcpiGetTimer(&t3); 134 135 do { 136 t1 = t2; 137 t2 = t3; 138 139 (void)AcpiGetTimer(&t3); 140 141 } while ((t1 > t2) || (t2 > t3)); 142 143 return t2; 144 } 145 146 uint32_t 147 acpitimer_delta(uint32_t end, uint32_t start) 148 { 149 const u_int mask = acpi_timecounter.tc_counter_mask; 150 uint32_t delta; 151 152 if (end >= start) 153 delta = end - start; 154 else 155 delta = ((mask - start) + end + 1) & mask; 156 157 return delta; 158 } 159 160 #define N 2000 161 162 static int 163 acpitimer_test(void) 164 { 165 uint32_t last, this, delta; 166 int minl, maxl, n; 167 168 minl = 10000000; 169 maxl = 0; 170 171 acpi_md_OsDisableInterrupt(); 172 173 (void)AcpiGetTimer(&last); 174 175 for (n = 0; n < N; n++) { 176 177 (void)AcpiGetTimer(&this); 178 179 delta = acpitimer_delta(this, last); 180 181 if (delta > maxl) 182 maxl = delta; 183 else if (delta < minl) 184 minl = delta; 185 186 last = this; 187 } 188 189 acpi_md_OsEnableInterrupt(); 190 191 if (maxl - minl > 2 ) 192 n = 0; 193 else if (minl < 0 || maxl == 0) 194 n = 0; 195 else 196 n = 1; 197 198 return n; 199 } 200 #endif 201