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s390/udelay: make it work for the early code 

Currently udelay relies on working EXT interrupts handler, which is not
the case during early startup. In such cases udelay_simple() has to be
used instead.

To avoid mistakes of calling udelay too early, which could happen from
the common code as well - make udelay work for the early code by
introducing static branch and redirecting all udelay calls to
udelay_simple until EXT interrupts handler is fully initialized and
async stack is allocated.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2020-10-13 22:35:27 +02:00 committed by Heiko Carstens
parent 13b5bd8af4
commit 85cde0192a
3 changed files with 15 additions and 0 deletions
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1
arch/s390/include/asm/delay.h
View File

@ -13,6 +13,7 @@
#ifndef _S390_DELAY_H
#define _S390_DELAY_H
void udelay_enable(void);
void __ndelay(unsigned long long nsecs);
void __udelay(unsigned long long usecs);
void udelay_simple(unsigned long long usecs);

1
arch/s390/kernel/setup.c
View File

@ -336,6 +336,7 @@ int __init arch_early_irq_init(void)
if (!stack)
panic("Couldn't allocate async stack");
S390_lowcore.async_stack = stack + STACK_INIT_OFFSET;
udelay_enable();
return 0;
}

13
arch/s390/lib/delay.c
View File

@ -13,11 +13,19 @@
#include <linux/export.h>
#include <linux/irqflags.h>
#include <linux/interrupt.h>
#include <linux/jump_label.h>
#include <linux/irq.h>
#include <asm/vtimer.h>
#include <asm/div64.h>
#include <asm/idle.h>
static DEFINE_STATIC_KEY_FALSE(udelay_ready);
void __init udelay_enable(void)
{
static_branch_enable(&udelay_ready);
}
void __delay(unsigned long loops)
{
/*
@ -77,6 +85,11 @@ void __udelay(unsigned long long usecs)
{
unsigned long flags;
if (!static_branch_likely(&udelay_ready)) {
udelay_simple(usecs);
return;
}
preempt_disable();
local_irq_save(flags);
if (in_irq()) {