u-boot/arch/arm/cpu/armv8/generic_timer.c
York Sun 060ef09460 armv8/fsl-lsch3: Implement workaround for erratum A008585
Generic Timer may contain an erroneous value. The workaround is to
read it twice until getting the same value.

Signed-off-by: York Sun <yorksun@freescale.com>
2015-04-23 08:55:54 -07:00

42 lines
930 B
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>
/*
* 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;
}