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