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/*
* 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/irqflags.h>
#include <linux/interrupt.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));
}
static void __udelay_disabled(unsigned long usecs)
{
unsigned long mask, cr0, cr0_saved;
u64 clock_saved;
clock_saved = local_tick_disable();
set_clock_comparator(get_clock() + ((u64) usecs << 12));
__ctl_store(cr0_saved, 0, 0);
cr0 = (cr0_saved & 0xffff00e0) | 0x00000800;
__ctl_load(cr0 , 0, 0);
mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
trace_hardirqs_on();
__load_psw_mask(mask);
local_irq_disable();
__ctl_load(cr0_saved, 0, 0);
local_tick_enable(clock_saved);
set_clock_comparator(S390_lowcore.clock_comparator);
}
static void __udelay_enabled(unsigned long usecs)
{
unsigned long mask;
u64 end, time;
mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT | PSW_MASK_IO;
end = get_clock() + ((u64) usecs << 12);
do {
time = end < S390_lowcore.clock_comparator ?
end : S390_lowcore.clock_comparator;
set_clock_comparator(time);
trace_hardirqs_on();
__load_psw_mask(mask);
local_irq_disable();
} while (get_clock() < end);
set_clock_comparator(S390_lowcore.clock_comparator);
}
/*
* Waits for 'usecs' microseconds using the TOD clock comparator.
*/
void __udelay(unsigned 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();
}
/*
* Simple udelay variant. To be used on startup and reboot
* when the interrupt handler isn't working.
*/
void udelay_simple(unsigned long usecs)
{
u64 end;
end = get_clock() + ((u64) usecs << 12);
while (get_clock() < end)
cpu_relax();
}
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