dccp: do not assume DCCP code is non preemptible
[linux/fpc-iii.git] / arch / ia64 / sn / kernel / sn2 / timer.c
blobabab8f99e9139a7822b22f166ffe3c6e03700863
1 /*
2 * linux/arch/ia64/sn/kernel/sn2/timer.c
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 */
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>
16 #include <asm/hw_irq.h>
17 #include <asm/timex.h>
19 #include <asm/sn/leds.h>
20 #include <asm/sn/shub_mmr.h>
21 #include <asm/sn/clksupport.h>
23 extern unsigned long sn_rtc_cycles_per_second;
25 static cycle_t read_sn2(struct clocksource *cs)
27 return (cycle_t)readq(RTC_COUNTER_ADDR);
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,
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.
43 static void
44 ia64_sn_udelay (unsigned long usecs)
46 unsigned long start = rtc_time();
47 unsigned long end = start +
48 usecs * sn_rtc_cycles_per_second / 1000000;
50 while (time_before((unsigned long)rtc_time(), end))
51 cpu_relax();
54 void __init sn_timer_init(void)
56 clocksource_sn2.archdata.fsys_mmio = RTC_COUNTER_ADDR;
57 clocksource_register_hz(&clocksource_sn2, sn_rtc_cycles_per_second);
59 ia64_udelay = &ia64_sn_udelay;