u-boot/arch/arm/cpu/armv8/generic_timer.c

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/*
* (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>
/*
* 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 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;
}