130 lines
3.0 KiB
C
130 lines
3.0 KiB
C
|
// 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;
|
||
|
|
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);
|
||
|
|
psw_idle(&idle, psw_mask);
|
||
|
|
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);
|