117 lines
2.8 KiB
C
117 lines
2.8 KiB
C
|
/*
|
||
|
|
* 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/module.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 long usecs)
|
||
|
|
{
|
||
|
|
unsigned long mask, cr0, cr0_saved;
|
||
|
|
u64 clock_saved;
|
||
|
|
|
||
|
|
clock_saved = local_tick_disable();
|
||
|
|
set_clock_comparator(get_clock() + (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;
|
||
|
|
lockdep_off();
|
||
|
|
trace_hardirqs_on();
|
||
|
|
__load_psw_mask(mask);
|
||
|
|
local_irq_disable();
|
||
|
|
lockdep_on();
|
||
|
|
__ctl_load(cr0_saved, 0, 0);
|
||
|
|
local_tick_enable(clock_saved);
|
||
|
|
set_clock_comparator(S390_lowcore.clock_comparator);
|
||
|
|
}
|
||
|
|
|
||
|
|
static void __udelay_enabled(unsigned long long usecs)
|
||
|
|
{
|
||
|
|
unsigned long mask;
|
||
|
|
u64 clock_saved;
|
||
|
|
u64 end;
|
||
|
|
|
||
|
|
mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT | PSW_MASK_IO;
|
||
|
|
end = get_clock() + (usecs << 12);
|
||
|
|
do {
|
||
|
|
clock_saved = 0;
|
||
|
|
if (end < S390_lowcore.clock_comparator) {
|
||
|
|
clock_saved = local_tick_disable();
|
||
|
|
set_clock_comparator(end);
|
||
|
|
}
|
||
|
|
trace_hardirqs_on();
|
||
|
|
__load_psw_mask(mask);
|
||
|
|
local_irq_disable();
|
||
|
|
if (clock_saved)
|
||
|
|
local_tick_enable(clock_saved);
|
||
|
|
} while (get_clock() < end);
|
||
|
|
set_clock_comparator(S390_lowcore.clock_comparator);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 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_clock() + (usecs << 12);
|
||
|
|
while (get_clock() < end)
|
||
|
|
cpu_relax();
|
||
|
|
}
|