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/*
* arch/s390/lib/delay.c
* Precise Delay Loops for S390
*
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
*
* Derived from "arch/i386/lib/delay.c"
* Copyright (C) 1993 Linus Torvalds
* Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
*/
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/timex.h>
#include <linux/irqflags.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));
}
/*
* Waits for 'usecs' microseconds using the TOD clock comparator.
*/
void __udelay(unsigned long usecs)
{
u64 end, time, jiffy_timer = 0;
unsigned long flags, cr0, mask, dummy;
local_irq_save(flags);
if (raw_irqs_disabled_flags(flags)) {
jiffy_timer = S390_lowcore.jiffy_timer;
S390_lowcore.jiffy_timer = -1ULL - (4096 << 12);
__ctl_store(cr0, 0, 0);
dummy = (cr0 & 0xffff00e0) | 0x00000800;
__ctl_load(dummy , 0, 0);
mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
} else
mask = psw_kernel_bits | PSW_MASK_WAIT |
PSW_MASK_EXT | PSW_MASK_IO;
end = get_clock() + ((u64) usecs << 12);
do {
time = end < S390_lowcore.jiffy_timer ?
end : S390_lowcore.jiffy_timer;
set_clock_comparator(time);
trace_hardirqs_on();
__load_psw_mask(mask);
local_irq_disable();
} while (get_clock() < end);
if (raw_irqs_disabled_flags(flags)) {
__ctl_load(cr0, 0, 0);
S390_lowcore.jiffy_timer = jiffy_timer;
}
set_clock_comparator(S390_lowcore.jiffy_timer);
local_irq_restore(flags);
}
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