1/*
2 * linux/arch/ia64/sn/kernel/sn2/timer.c
3 *
4 * Copyright (C) 2003 Silicon Graphics, Inc.
5 * Copyright (C) 2003 Hewlett-Packard Co
6 *	David Mosberger <davidm@hpl.hp.com>: updated for new timer-interpolation infrastructure
7 */
8
9#include <linux/init.h>
10#include <linux/kernel.h>
11#include <linux/sched.h>
12#include <linux/time.h>
13#include <linux/interrupt.h>
14
15#include <asm/hw_irq.h>
16#include <asm/system.h>
17#include <asm/timex.h>
18
19#include <asm/sn/leds.h>
20#include <asm/sn/shub_mmr.h>
21#include <asm/sn/clksupport.h>
22
23extern unsigned long sn_rtc_cycles_per_second;
24
25static struct time_interpolator sn2_interpolator = {
26	.drift = -1,
27	.shift = 10,
28	.mask = (1LL << 55) - 1,
29	.source = TIME_SOURCE_MMIO64
30};
31
32/*
33 * sn udelay uses the RTC instead of the ITC because the ITC is not
34 * synchronized across all CPUs, and the thread may migrate to another CPU
35 * if preemption is enabled.
36 */
37static void
38ia64_sn_udelay (unsigned long usecs)
39{
40	unsigned long start = rtc_time();
41	unsigned long end = start +
42			usecs * sn_rtc_cycles_per_second / 1000000;
43
44	while (time_before((unsigned long)rtc_time(), end))
45		cpu_relax();
46}
47
48void __init sn_timer_init(void)
49{
50	sn2_interpolator.frequency = sn_rtc_cycles_per_second;
51	sn2_interpolator.addr = RTC_COUNTER_ADDR;
52	register_time_interpolator(&sn2_interpolator);
53
54	ia64_udelay = &ia64_sn_udelay;
55}
56