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/*
* linux/arch/ia64/sn/kernel/sn2/timer.c
*
* Copyright (C) 2003 Silicon Graphics, Inc.
* Copyright (C) 2003 Hewlett-Packard Co
* David Mosberger <davidm@hpl.hp.com>: updated for new timer-interpolation infrastructure
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/clocksource.h>
#include <asm/hw_irq.h>
#include <asm/system.h>
#include <asm/timex.h>
#include <asm/sn/leds.h>
#include <asm/sn/shub_mmr.h>
#include <asm/sn/clksupport.h>
extern unsigned long sn_rtc_cycles_per_second;
static void __iomem *sn2_mc;
static cycle_t read_sn2(void)
{
return (cycle_t)readq(sn2_mc);
}
static struct clocksource clocksource_sn2 = {
.name = "sn2_rtc",
.rating = 300,
.read = read_sn2,
.mask = (1LL << 55) - 1,
.mult = 0,
.shift = 10,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
/*
* sn udelay uses the RTC instead of the ITC because the ITC is not
* synchronized across all CPUs, and the thread may migrate to another CPU
* if preemption is enabled.
*/
static void
ia64_sn_udelay (unsigned long usecs)
{
unsigned long start = rtc_time();
unsigned long end = start +
usecs * sn_rtc_cycles_per_second / 1000000;
while (time_before((unsigned long)rtc_time(), end))
cpu_relax();
}
void __init sn_timer_init(void)
{
sn2_mc = RTC_COUNTER_ADDR;
clocksource_sn2.fsys_mmio = RTC_COUNTER_ADDR;
clocksource_sn2.mult = clocksource_hz2mult(sn_rtc_cycles_per_second,
clocksource_sn2.shift);
clocksource_register(&clocksource_sn2);
ia64_udelay = &ia64_sn_udelay;
}
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