u-boot-brain/lib/time.c
Sean Anderson 4b2be78ab6 time: Fix get_ticks being non-monotonic
get_ticks does not always succeed. Sometimes it can be called before the
timer has been initialized. If it does, it returns a negative errno.
This causes the timer to appear non-monotonic, because the value will
become much smaller after the timer is initialized.

No users of get_ticks which I checked handle errors of this kind. Further,
functions like tick_to_time mangle the result of get_ticks, making it very
unlikely that one could check for an error without suggesting a patch such
as this one.

This patch panics if we ever get an error. There are two cases in which
this can occur. The first is if we couldn't find/probe the timer for some
reason. One reason for this is if the timer is not available so early. This
likely indicates misconfiguration. Another reason is that the timer has an
invalid/missing device tree binding. In this case, panicing is also
correct. The second case covers errors calling get_count. This can only
occur if the timer is missing a get_count function (or on RISC-V, but that
should be fixed soon).

Fixes: c8a7ba9e6a
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2020-10-14 11:16:34 -04:00

196 lines
3.5 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* (C) Copyright 2000-2009
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*/
#include <common.h>
#include <bootstage.h>
#include <dm.h>
#include <errno.h>
#include <init.h>
#include <time.h>
#include <timer.h>
#include <watchdog.h>
#include <div64.h>
#include <asm/io.h>
#include <linux/delay.h>
#ifndef CONFIG_WD_PERIOD
# define CONFIG_WD_PERIOD (10 * 1000 * 1000) /* 10 seconds default */
#endif
DECLARE_GLOBAL_DATA_PTR;
#ifdef CONFIG_SYS_TIMER_RATE
/* Returns tick rate in ticks per second */
ulong notrace get_tbclk(void)
{
return CONFIG_SYS_TIMER_RATE;
}
#endif
#ifdef CONFIG_SYS_TIMER_COUNTER
unsigned long notrace timer_read_counter(void)
{
#ifdef CONFIG_SYS_TIMER_COUNTS_DOWN
return ~readl(CONFIG_SYS_TIMER_COUNTER);
#else
return readl(CONFIG_SYS_TIMER_COUNTER);
#endif
}
ulong timer_get_boot_us(void)
{
ulong count = timer_read_counter();
#if CONFIG_SYS_TIMER_RATE == 1000000
return count;
#elif CONFIG_SYS_TIMER_RATE > 1000000
return lldiv(count, CONFIG_SYS_TIMER_RATE / 1000000);
#elif defined(CONFIG_SYS_TIMER_RATE)
return (unsigned long long)count * 1000000 / CONFIG_SYS_TIMER_RATE;
#else
/* Assume the counter is in microseconds */
return count;
#endif
}
#else
extern unsigned long __weak timer_read_counter(void);
#endif
#if CONFIG_IS_ENABLED(TIMER)
ulong notrace get_tbclk(void)
{
if (!gd->timer) {
#ifdef CONFIG_TIMER_EARLY
return timer_early_get_rate();
#else
int ret;
ret = dm_timer_init();
if (ret)
return ret;
#endif
}
return timer_get_rate(gd->timer);
}
uint64_t notrace get_ticks(void)
{
u64 count;
int ret;
if (!gd->timer) {
#ifdef CONFIG_TIMER_EARLY
return timer_early_get_count();
#else
int ret;
ret = dm_timer_init();
if (ret)
panic("Could not initialize timer (err %d)\n", ret);
#endif
}
ret = timer_get_count(gd->timer, &count);
if (ret)
panic("Could not read count from timer (err %d)\n", ret);
return count;
}
#else /* !CONFIG_TIMER */
uint64_t __weak notrace get_ticks(void)
{
unsigned long now = timer_read_counter();
/* increment tbu if tbl has rolled over */
if (now < gd->timebase_l)
gd->timebase_h++;
gd->timebase_l = now;
return ((uint64_t)gd->timebase_h << 32) | gd->timebase_l;
}
#endif /* CONFIG_TIMER */
/* Returns time in milliseconds */
static uint64_t notrace tick_to_time(uint64_t tick)
{
ulong div = get_tbclk();
tick *= CONFIG_SYS_HZ;
do_div(tick, div);
return tick;
}
int __weak timer_init(void)
{
return 0;
}
/* Returns time in milliseconds */
ulong __weak get_timer(ulong base)
{
return tick_to_time(get_ticks()) - base;
}
static uint64_t notrace tick_to_time_us(uint64_t tick)
{
ulong div = get_tbclk() / 1000;
tick *= CONFIG_SYS_HZ;
do_div(tick, div);
return tick;
}
uint64_t __weak get_timer_us(uint64_t base)
{
return tick_to_time_us(get_ticks()) - base;
}
unsigned long __weak get_timer_us_long(unsigned long base)
{
return timer_get_us() - base;
}
unsigned long __weak notrace timer_get_us(void)
{
return tick_to_time(get_ticks() * 1000);
}
uint64_t usec_to_tick(unsigned long usec)
{
uint64_t tick = usec;
tick *= get_tbclk();
do_div(tick, 1000000);
return tick;
}
void __weak __udelay(unsigned long usec)
{
uint64_t tmp;
tmp = get_ticks() + usec_to_tick(usec); /* get current timestamp */
while (get_ticks() < tmp+1) /* loop till event */
/*NOP*/;
}
/* ------------------------------------------------------------------------- */
void udelay(unsigned long usec)
{
ulong kv;
do {
WATCHDOG_RESET();
kv = usec > CONFIG_WD_PERIOD ? CONFIG_WD_PERIOD : usec;
__udelay(kv);
usec -= kv;
} while(usec);
}