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#include <linux/clocksource.h> 15 16#include <asm/hw_irq.h> 17#include <asm/system.h> 18#include <asm/timex.h> 19 20#include <asm/sn/leds.h> 21#include <asm/sn/shub_mmr.h> 22#include <asm/sn/clksupport.h> 23 24extern unsigned long sn_rtc_cycles_per_second; 25 26static cycle_t read_sn2(struct clocksource *cs) 27{ 28 return (cycle_t)readq(RTC_COUNTER_ADDR); 29} 30 31static struct clocksource clocksource_sn2 = { 32 .name = "sn2_rtc", 33 .rating = 450, 34 .read = read_sn2, 35 .mask = (1LL << 55) - 1, 36 .mult = 0, 37 .shift = 10, 38 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 39}; 40 41/* 42 * sn udelay uses the RTC instead of the ITC because the ITC is not 43 * synchronized across all CPUs, and the thread may migrate to another CPU 44 * if preemption is enabled. 45 */ 46static void 47ia64_sn_udelay (unsigned long usecs) 48{ 49 unsigned long start = rtc_time(); 50 unsigned long end = start + 51 usecs * sn_rtc_cycles_per_second / 1000000; 52 53 while (time_before((unsigned long)rtc_time(), end)) 54 cpu_relax(); 55} 56 57void __init sn_timer_init(void) 58{ 59 clocksource_sn2.fsys_mmio = RTC_COUNTER_ADDR; 60 clocksource_sn2.mult = clocksource_hz2mult(sn_rtc_cycles_per_second, 61 clocksource_sn2.shift); 62 clocksource_register(&clocksource_sn2); 63 64 ia64_udelay = &ia64_sn_udelay; 65} 66