u-boot/arch/arm/cpu/armv8/generic_timer.c
Andre Przywara 68fd5c136c armv8: define get_ticks() for the ARMv8 Generic Timer
For 64-bit ARM systems we provide just a timer_read_counter()
implementation and rely on the generic non-uclass get_ticks() function
in lib/time.c to call the former.
However this function is actually not 64-bit safe, as it assumes a
"long" to be 32-bit. Beside the fact that the resulting uint64_t
isn't bigger than "long" on 64-bit architectures and thus combining two
counters makes no sense, we get all kind of weird results when we try
to OR in the high value shifted by _32_ bits.
So let's avoid that function at all and provide a straight forward
get_ticks() implementation for ARMv8, which also is in line with ARMv7.

This fixes occasional immediate time-out expiration issues I see on the
Pine64 board. The root cause of this needs to be investigated, but this
fix looks like the right thing anyway.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
2016-11-05 07:27:45 -04:00

64 lines
1.3 KiB
C

/*
* (C) Copyright 2013
* David Feng <fenghua@phytium.com.cn>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <command.h>
#include <asm/system.h>
DECLARE_GLOBAL_DATA_PTR;
/*
* Generic timer implementation of get_tbclk()
*/
unsigned long get_tbclk(void)
{
unsigned long cntfrq;
asm volatile("mrs %0, cntfrq_el0" : "=r" (cntfrq));
return cntfrq;
}
/*
* Generic timer implementation of timer_read_counter()
*/
unsigned long timer_read_counter(void)
{
unsigned long cntpct;
#ifdef CONFIG_SYS_FSL_ERRATUM_A008585
/* This erratum number needs to be confirmed to match ARM document */
unsigned long temp;
#endif
isb();
asm volatile("mrs %0, cntpct_el0" : "=r" (cntpct));
#ifdef CONFIG_SYS_FSL_ERRATUM_A008585
asm volatile("mrs %0, cntpct_el0" : "=r" (temp));
while (temp != cntpct) {
asm volatile("mrs %0, cntpct_el0" : "=r" (cntpct));
asm volatile("mrs %0, cntpct_el0" : "=r" (temp));
}
#endif
return cntpct;
}
unsigned long long get_ticks(void)
{
unsigned long ticks = timer_read_counter();
gd->arch.tbl = ticks;
return ticks;
}
unsigned long usec2ticks(unsigned long usec)
{
ulong ticks;
if (usec < 1000)
ticks = ((usec * (get_tbclk()/1000)) + 500) / 1000;
else
ticks = ((usec / 10) * (get_tbclk() / 100000));
return ticks;
}