| 1 | /*␊ |
| 2 | * This file is part of the flashrom project.␊ |
| 3 | *␊ |
| 4 | * Copyright (C) 2000 Silicon Integrated System Corporation␊ |
| 5 | * Copyright (C) 2009,2010 Carl-Daniel Hailfinger␊ |
| 6 | *␊ |
| 7 | * This program is free software; you can redistribute it and/or modify␊ |
| 8 | * it under the terms of the GNU General Public License as published by␊ |
| 9 | * the Free Software Foundation; either version 2 of the License, or␊ |
| 10 | * (at your option) any later version.␊ |
| 11 | *␊ |
| 12 | * This program is distributed in the hope that it will be useful,␊ |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of␊ |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the␊ |
| 15 | * GNU General Public License for more details.␊ |
| 16 | *␊ |
| 17 | * You should have received a copy of the GNU General Public License␊ |
| 18 | * along with this program; if not, write to the Free Software␊ |
| 19 | * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA␊ |
| 20 | */␊ |
| 21 | ␊ |
| 22 | #ifndef __LIBPAYLOAD__␊ |
| 23 | ␊ |
| 24 | #include <unistd.h>␊ |
| 25 | #include <sys/time.h>␊ |
| 26 | #include <stdlib.h>␊ |
| 27 | #include <limits.h>␊ |
| 28 | #include "flash.h"␊ |
| 29 | ␊ |
| 30 | /* loops per microsecond */␊ |
| 31 | static unsigned long micro = 1;␊ |
| 32 | ␊ |
| 33 | __attribute__ ((noinline)) void myusec_delay(int usecs)␊ |
| 34 | {␊ |
| 35 | ␉unsigned long i;␊ |
| 36 | ␉for (i = 0; i < usecs * micro; i++) {␊ |
| 37 | ␉␉/* Make sure the compiler doesn't optimize the loop away. */␊ |
| 38 | ␉␉asm volatile ("" : : "rm" (i) );␊ |
| 39 | ␉}␊ |
| 40 | }␊ |
| 41 | ␊ |
| 42 | static unsigned long measure_os_delay_resolution(void)␊ |
| 43 | {␊ |
| 44 | ␉unsigned long timeusec;␊ |
| 45 | ␉struct timeval start, end;␊ |
| 46 | ␉unsigned long counter = 0;␊ |
| 47 | ␉␊ |
| 48 | ␉gettimeofday(&start, NULL);␊ |
| 49 | ␉timeusec = 0;␊ |
| 50 | ␉␊ |
| 51 | ␉while (!timeusec && (++counter < 1000000000)) {␊ |
| 52 | ␉␉gettimeofday(&end, NULL);␊ |
| 53 | ␉␉timeusec = 1000000 * (end.tv_sec - start.tv_sec) +␊ |
| 54 | ␉␉␉ (end.tv_usec - start.tv_usec);␊ |
| 55 | ␉␉/* Protect against time going forward too much. */␊ |
| 56 | ␉␉if ((end.tv_sec > start.tv_sec) &&␊ |
| 57 | ␉␉ ((end.tv_sec - start.tv_sec) >= LONG_MAX / 1000000 - 1))␊ |
| 58 | ␉␉␉timeusec = 0;␊ |
| 59 | ␉␉/* Protect against time going backwards during leap seconds. */␊ |
| 60 | ␉␉if ((end.tv_sec < start.tv_sec) || (timeusec > LONG_MAX))␊ |
| 61 | ␉␉␉timeusec = 0;␊ |
| 62 | ␉}␊ |
| 63 | ␉return timeusec;␊ |
| 64 | }␊ |
| 65 | ␊ |
| 66 | static unsigned long measure_delay(int usecs)␊ |
| 67 | {␊ |
| 68 | ␉unsigned long timeusec;␊ |
| 69 | ␉struct timeval start, end;␊ |
| 70 | ␉␊ |
| 71 | ␉gettimeofday(&start, NULL);␊ |
| 72 | ␉myusec_delay(usecs);␊ |
| 73 | ␉gettimeofday(&end, NULL);␊ |
| 74 | ␉timeusec = 1000000 * (end.tv_sec - start.tv_sec) +␊ |
| 75 | ␉␉ (end.tv_usec - start.tv_usec);␊ |
| 76 | ␉/* Protect against time going forward too much. */␊ |
| 77 | ␉if ((end.tv_sec > start.tv_sec) &&␊ |
| 78 | ␉ ((end.tv_sec - start.tv_sec) >= LONG_MAX / 1000000 - 1))␊ |
| 79 | ␉␉timeusec = LONG_MAX;␊ |
| 80 | ␉/* Protect against time going backwards during leap seconds. */␊ |
| 81 | ␉if ((end.tv_sec < start.tv_sec) || (timeusec > LONG_MAX))␊ |
| 82 | ␉␉timeusec = 1;␊ |
| 83 | ␊ |
| 84 | ␉return timeusec;␊ |
| 85 | }␊ |
| 86 | ␊ |
| 87 | void myusec_calibrate_delay(void)␊ |
| 88 | {␊ |
| 89 | ␉unsigned long count = 1000;␊ |
| 90 | ␉unsigned long timeusec, resolution;␊ |
| 91 | ␉int i, tries = 0;␊ |
| 92 | ␊ |
| 93 | ␉msg_pinfo("Calibrating delay loop... ");␊ |
| 94 | ␉resolution = measure_os_delay_resolution();␊ |
| 95 | ␉if (resolution) {␊ |
| 96 | ␉␉msg_pdbg("OS timer resolution is %lu usecs, ", resolution);␊ |
| 97 | ␉} else {␊ |
| 98 | ␉␉msg_pinfo("OS timer resolution is unusable. ");␊ |
| 99 | ␉}␊ |
| 100 | ␊ |
| 101 | recalibrate:␊ |
| 102 | ␉count = 1000;␊ |
| 103 | ␉while (1) {␊ |
| 104 | ␉␉timeusec = measure_delay(count);␊ |
| 105 | ␉␉if (timeusec > 1000000 / 4)␊ |
| 106 | ␉␉␉break;␊ |
| 107 | ␉␉if (count >= ULONG_MAX / 2) {␊ |
| 108 | ␉␉␉msg_pinfo("timer loop overflow, reduced precision. ");␊ |
| 109 | ␉␉␉break;␊ |
| 110 | ␉␉}␊ |
| 111 | ␉␉count *= 2;␊ |
| 112 | ␉}␊ |
| 113 | ␉tries ++;␊ |
| 114 | ␊ |
| 115 | ␉/* Avoid division by zero, but in that case the loop is shot anyway. */␊ |
| 116 | ␉if (!timeusec)␊ |
| 117 | ␉␉timeusec = 1;␊ |
| 118 | ␉␊ |
| 119 | ␉/* Compute rounded up number of loops per microsecond. */␊ |
| 120 | ␉micro = (count * micro) / timeusec + 1;␊ |
| 121 | ␉msg_pdbg("%luM loops per second, ", micro);␊ |
| 122 | ␊ |
| 123 | ␉/* Did we try to recalibrate less than 5 times? */␊ |
| 124 | ␉if (tries < 5) {␊ |
| 125 | ␉␉/* Recheck our timing to make sure we weren't just hitting␊ |
| 126 | ␉␉ * a scheduler delay or something similar.␊ |
| 127 | ␉␉ */␊ |
| 128 | ␉␉for (i = 0; i < 4; i++) {␊ |
| 129 | ␉␉␉if (resolution && (resolution < 10)) {␊ |
| 130 | ␉␉␉␉timeusec = measure_delay(100);␊ |
| 131 | ␉␉␉} else if (resolution && ␊ |
| 132 | ␉␉␉␉ (resolution < ULONG_MAX / 200)) {␊ |
| 133 | ␉␉␉␉timeusec = measure_delay(resolution * 10) *␊ |
| 134 | ␉␉␉␉␉ 100 / (resolution * 10);␊ |
| 135 | ␉␉␉} else {␊ |
| 136 | ␉␉␉␉/* This workaround should be active for broken␊ |
| 137 | ␉␉␉␉ * OS and maybe libpayload. The criterion␊ |
| 138 | ␉␉␉␉ * here is horrible or non-measurable OS timer␊ |
| 139 | ␉␉␉␉ * resolution which will result in␊ |
| 140 | ␉␉␉␉ * measure_delay(100)=0 whereas a longer delay␊ |
| 141 | ␉␉␉␉ * (1000 ms) may be sufficient␊ |
| 142 | ␉␉␉␉ * to get a nonzero time measurement.␊ |
| 143 | ␉␉␉␉ */␊ |
| 144 | ␉␉␉␉timeusec = measure_delay(1000000) / 10000;␊ |
| 145 | ␉␉␉}␊ |
| 146 | ␉␉␉if (timeusec < 90) {␊ |
| 147 | ␉␉␉␉msg_pdbg("delay more than 10%% too short (got "␊ |
| 148 | ␉␉␉␉␉ "%lu%% of expected delay), "␊ |
| 149 | ␉␉␉␉␉ "recalculating... ", timeusec);␊ |
| 150 | ␉␉␉␉goto recalibrate;␊ |
| 151 | ␉␉␉}␊ |
| 152 | ␉␉}␊ |
| 153 | ␉} else {␊ |
| 154 | ␉␉msg_perr("delay loop is unreliable, trying to continue ");␊ |
| 155 | ␉}␊ |
| 156 | ␊ |
| 157 | ␉/* We're interested in the actual precision. */␊ |
| 158 | ␉timeusec = measure_delay(10);␊ |
| 159 | ␉msg_pdbg("10 myus = %ld us, ", timeusec);␊ |
| 160 | ␉timeusec = measure_delay(100);␊ |
| 161 | ␉msg_pdbg("100 myus = %ld us, ", timeusec);␊ |
| 162 | ␉timeusec = measure_delay(1000);␊ |
| 163 | ␉msg_pdbg("1000 myus = %ld us, ", timeusec);␊ |
| 164 | ␉timeusec = measure_delay(10000);␊ |
| 165 | ␉msg_pdbg("10000 myus = %ld us, ", timeusec);␊ |
| 166 | ␉timeusec = measure_delay(resolution * 4);␊ |
| 167 | ␉msg_pdbg("%ld myus = %ld us, ", resolution * 4, timeusec);␊ |
| 168 | ␊ |
| 169 | ␉msg_pinfo("OK.\n");␊ |
| 170 | }␊ |
| 171 | ␊ |
| 172 | void internal_delay(int usecs)␊ |
| 173 | {␊ |
| 174 | ␉/* If the delay is >1 s, use usleep because timing does not need to␊ |
| 175 | ␉ * be so precise.␊ |
| 176 | ␉ */␊ |
| 177 | ␉if (usecs > 1000000) {␊ |
| 178 | ␉␉usleep(usecs);␊ |
| 179 | ␉} else {␊ |
| 180 | ␉␉myusec_delay(usecs);␊ |
| 181 | ␉}␊ |
| 182 | }␊ |
| 183 | ␊ |
| 184 | #else ␊ |
| 185 | #include <libpayload.h>␊ |
| 186 | ␊ |
| 187 | void myusec_calibrate_delay(void)␊ |
| 188 | {␊ |
| 189 | ␉get_cpu_speed();␊ |
| 190 | }␊ |
| 191 | ␊ |
| 192 | void internal_delay(int usecs)␊ |
| 193 | {␊ |
| 194 | ␉udelay(usecs);␊ |
| 195 | }␊ |
| 196 | #endif␊ |
| 197 | |
