blob: f6fd103ca0d6e7a7b2a035b562927f93ea86f888 [file] [log] [blame]
/*
* This file is part of the flashrom project.
*
* Copyright (C) 2000 Silicon Integrated System Corporation
* Copyright (C) 2009,2010 Carl-Daniel Hailfinger
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#ifndef __LIBPAYLOAD__
#include <stdbool.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <sys/time.h>
#include <stdlib.h>
#include <limits.h>
#include "flash.h"
static bool use_clock_gettime = false;
#if HAVE_CLOCK_GETTIME == 1
#ifdef _POSIX_MONOTONIC_CLOCK
static clockid_t clock_id = CLOCK_MONOTONIC;
#else
static clockid_t clock_id = CLOCK_REALTIME;
#endif
static void clock_usec_delay(int usecs)
{
struct timespec now;
clock_gettime(clock_id, &now);
const long end_nsec = now.tv_nsec + usecs * 1000L;
const struct timespec end = {
end_nsec / (1000 * 1000 * 1000) + now.tv_sec,
end_nsec % (1000 * 1000 * 1000)
};
do {
clock_gettime(clock_id, &now);
} while (now.tv_sec < end.tv_sec || (now.tv_sec == end.tv_sec && now.tv_nsec < end.tv_nsec));
}
static int clock_check_res(void)
{
struct timespec res;
if (!clock_getres(clock_id, &res)) {
if (res.tv_sec == 0 && res.tv_nsec <= 100) {
msg_pinfo("Using clock_gettime for delay loops (clk_id: %d, resolution: %ldns).\n",
(int)clock_id, res.tv_nsec);
use_clock_gettime = true;
return 1;
}
} else if (clock_id != CLOCK_REALTIME && errno == EINVAL) {
/* Try again with CLOCK_REALTIME. */
clock_id = CLOCK_REALTIME;
return clock_check_res();
}
return 0;
}
#else
static inline void clock_usec_delay(int usecs) {}
static inline int clock_check_res(void) { return 0; }
#endif /* HAVE_CLOCK_GETTIME == 1 */
/* loops per microsecond */
static unsigned long micro = 1;
__attribute__ ((noinline)) void myusec_delay(unsigned int usecs)
{
unsigned long i;
for (i = 0; i < usecs * micro; i++) {
/* Make sure the compiler doesn't optimize the loop away. */
__asm__ volatile ("" : : "rm" (i) );
}
}
static unsigned long measure_os_delay_resolution(void)
{
unsigned long timeusec;
struct timeval start, end;
unsigned long counter = 0;
gettimeofday(&start, NULL);
timeusec = 0;
while (!timeusec && (++counter < 1000000000)) {
gettimeofday(&end, NULL);
timeusec = 1000000 * (end.tv_sec - start.tv_sec) +
(end.tv_usec - start.tv_usec);
/* Protect against time going forward too much. */
if ((end.tv_sec > start.tv_sec) &&
((end.tv_sec - start.tv_sec) >= LONG_MAX / 1000000 - 1))
timeusec = 0;
/* Protect against time going backwards during leap seconds. */
if ((end.tv_sec < start.tv_sec) || (timeusec > LONG_MAX))
timeusec = 0;
}
return timeusec;
}
static unsigned long measure_delay(unsigned int usecs)
{
unsigned long timeusec;
struct timeval start, end;
gettimeofday(&start, NULL);
myusec_delay(usecs);
gettimeofday(&end, NULL);
timeusec = 1000000 * (end.tv_sec - start.tv_sec) +
(end.tv_usec - start.tv_usec);
/* Protect against time going forward too much. */
if ((end.tv_sec > start.tv_sec) &&
((end.tv_sec - start.tv_sec) >= LONG_MAX / 1000000 - 1))
timeusec = LONG_MAX;
/* Protect against time going backwards during leap seconds. */
if ((end.tv_sec < start.tv_sec) || (timeusec > LONG_MAX))
timeusec = 1;
return timeusec;
}
void myusec_calibrate_delay(void)
{
if (clock_check_res())
return;
unsigned long count = 1000;
unsigned long timeusec, resolution;
int i, tries = 0;
msg_pinfo("Calibrating delay loop... ");
resolution = measure_os_delay_resolution();
if (resolution) {
msg_pdbg("OS timer resolution is %lu usecs, ", resolution);
} else {
msg_pinfo("OS timer resolution is unusable. ");
}
recalibrate:
count = 1000;
while (1) {
timeusec = measure_delay(count);
if (timeusec > 1000000 / 4)
break;
if (count >= ULONG_MAX / 2) {
msg_pinfo("timer loop overflow, reduced precision. ");
break;
}
count *= 2;
}
tries ++;
/* Avoid division by zero, but in that case the loop is shot anyway. */
if (!timeusec)
timeusec = 1;
/* Compute rounded up number of loops per microsecond. */
micro = (count * micro) / timeusec + 1;
msg_pdbg("%luM loops per second, ", micro);
/* Did we try to recalibrate less than 5 times? */
if (tries < 5) {
/* Recheck our timing to make sure we weren't just hitting
* a scheduler delay or something similar.
*/
for (i = 0; i < 4; i++) {
if (resolution && (resolution < 10)) {
timeusec = measure_delay(100);
} else if (resolution &&
(resolution < ULONG_MAX / 200)) {
timeusec = measure_delay(resolution * 10) *
100 / (resolution * 10);
} else {
/* This workaround should be active for broken
* OS and maybe libpayload. The criterion
* here is horrible or non-measurable OS timer
* resolution which will result in
* measure_delay(100)=0 whereas a longer delay
* (1000 ms) may be sufficient
* to get a nonzero time measurement.
*/
timeusec = measure_delay(1000000) / 10000;
}
if (timeusec < 90) {
msg_pdbg("delay more than 10%% too short (got "
"%lu%% of expected delay), "
"recalculating... ", timeusec);
goto recalibrate;
}
}
} else {
msg_perr("delay loop is unreliable, trying to continue ");
}
/* We're interested in the actual precision. */
timeusec = measure_delay(10);
msg_pdbg("10 myus = %ld us, ", timeusec);
timeusec = measure_delay(100);
msg_pdbg("100 myus = %ld us, ", timeusec);
timeusec = measure_delay(1000);
msg_pdbg("1000 myus = %ld us, ", timeusec);
timeusec = measure_delay(10000);
msg_pdbg("10000 myus = %ld us, ", timeusec);
timeusec = measure_delay(resolution * 4);
msg_pdbg("%ld myus = %ld us, ", resolution * 4, timeusec);
msg_pinfo("OK.\n");
}
/* Not very precise sleep. */
void internal_sleep(unsigned int usecs)
{
#if IS_WINDOWS
Sleep((usecs + 999) / 1000);
#elif defined(__DJGPP__)
sleep(usecs / 1000000);
usleep(usecs % 1000000);
#else
nanosleep(&(struct timespec){usecs / 1000000, (usecs * 1000) % 1000000000UL}, NULL);
#endif
}
/* Precise delay. */
void internal_delay(unsigned int usecs)
{
/* If the delay is >1 s, use internal_sleep because timing does not need to be so precise. */
if (usecs > 1000000) {
internal_sleep(usecs);
} else if (use_clock_gettime) {
clock_usec_delay(usecs);
} else {
myusec_delay(usecs);
}
}
#else
#include <libpayload.h>
void myusec_calibrate_delay(void)
{
get_cpu_speed();
}
void internal_delay(unsigned int usecs)
{
udelay(usecs);
}
#endif