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