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// SPDX-License-Identifier: GPL-2.0
/*
* Precise Delay Loops for S390
*
* Copyright IBM Corp. 1999, 2008
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
* Heiko Carstens <heiko.carstens@de.ibm.com>,
*/
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/timex.h>
#include <linux/export.h>
#include <linux/irqflags.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <asm/vtimer.h>
#include <asm/div64.h>
#include <asm/idle.h>
void __delay(unsigned long loops)
{
/*
* To end the bloody studid and useless discussion about the
* BogoMips number I took the liberty to define the __delay
* function in a way that that resulting BogoMips number will
* yield the megahertz number of the cpu. The important function
* is udelay and that is done using the tod clock. -- martin.
*/
asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
}
EXPORT_SYMBOL(__delay);
static void __udelay_disabled(unsigned long long usecs)
{
unsigned long cr0, cr0_new, psw_mask, flags;
struct s390_idle_data idle;
u64 end;
end = get_tod_clock() + (usecs << 12);
__ctl_store(cr0, 0, 0);
cr0_new = cr0 & ~CR0_IRQ_SUBCLASS_MASK;
cr0_new |= (1UL << (63 - 52)); /* enable clock comparator irq */
__ctl_load(cr0_new, 0, 0);
psw_mask = __extract_psw() | PSW_MASK_EXT | PSW_MASK_WAIT;
set_clock_comparator(end);
set_cpu_flag(CIF_IGNORE_IRQ);
local_irq_save(flags);
psw_idle(&idle, psw_mask);
local_irq_restore(flags);
clear_cpu_flag(CIF_IGNORE_IRQ);
set_clock_comparator(S390_lowcore.clock_comparator);
__ctl_load(cr0, 0, 0);
}
static void __udelay_enabled(unsigned long long usecs)
{
u64 clock_saved, end;
end = get_tod_clock_fast() + (usecs << 12);
do {
clock_saved = 0;
if (tod_after(S390_lowcore.clock_comparator, end)) {
clock_saved = local_tick_disable();
set_clock_comparator(end);
}
enabled_wait();
if (clock_saved)
local_tick_enable(clock_saved);
} while (get_tod_clock_fast() < end);
}
/*
* Waits for 'usecs' microseconds using the TOD clock comparator.
*/
void __udelay(unsigned long long usecs)
{
unsigned long flags;
preempt_disable();
local_irq_save(flags);
if (in_irq()) {
__udelay_disabled(usecs);
goto out;
}
if (in_softirq()) {
if (raw_irqs_disabled_flags(flags))
__udelay_disabled(usecs);
else
__udelay_enabled(usecs);
goto out;
}
if (raw_irqs_disabled_flags(flags)) {
local_bh_disable();
__udelay_disabled(usecs);
_local_bh_enable();
goto out;
}
__udelay_enabled(usecs);
out:
local_irq_restore(flags);
preempt_enable();
}
EXPORT_SYMBOL(__udelay);
/*
* Simple udelay variant. To be used on startup and reboot
* when the interrupt handler isn't working.
*/
void udelay_simple(unsigned long long usecs)
{
u64 end;
end = get_tod_clock_fast() + (usecs << 12);
while (get_tod_clock_fast() < end)
cpu_relax();
}
void __ndelay(unsigned long long nsecs)
{
u64 end;
nsecs <<= 9;
do_div(nsecs, 125);
end = get_tod_clock_fast() + nsecs;
if (nsecs & ~0xfffUL)
__udelay(nsecs >> 12);
while (get_tod_clock_fast() < end)
barrier();
}
EXPORT_SYMBOL(__ndelay);
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