aboutsummaryrefslogtreecommitdiff
path: root/arch/ia64/sn/kernel/sn2/timer.c
blob: 19e25d2b64fcabdd003c7e239cf8938cc8200383 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
/*
 * linux/arch/ia64/sn/kernel/sn2/timer.c
 *
 * Copyright (C) 2003 Silicon Graphics, Inc.
 * Copyright (C) 2003 Hewlett-Packard Co
 *	David Mosberger <davidm@hpl.hp.com>: updated for new timer-interpolation infrastructure
 */

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/clocksource.h>

#include <asm/hw_irq.h>
#include <asm/system.h>
#include <asm/timex.h>

#include <asm/sn/leds.h>
#include <asm/sn/shub_mmr.h>
#include <asm/sn/clksupport.h>

extern unsigned long sn_rtc_cycles_per_second;

static void __iomem *sn2_mc;

static cycle_t read_sn2(void)
{
	return (cycle_t)readq(sn2_mc);
}

static struct clocksource clocksource_sn2 = {
        .name           = "sn2_rtc",
        .rating         = 300,
        .read           = read_sn2,
        .mask           = (1LL << 55) - 1,
        .mult           = 0,
        .shift          = 10,
        .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
};

/*
 * sn udelay uses the RTC instead of the ITC because the ITC is not
 * synchronized across all CPUs, and the thread may migrate to another CPU
 * if preemption is enabled.
 */
static void
ia64_sn_udelay (unsigned long usecs)
{
	unsigned long start = rtc_time();
	unsigned long end = start +
			usecs * sn_rtc_cycles_per_second / 1000000;

	while (time_before((unsigned long)rtc_time(), end))
		cpu_relax();
}

void __init sn_timer_init(void)
{
	sn2_mc = RTC_COUNTER_ADDR;
	clocksource_sn2.fsys_mmio = RTC_COUNTER_ADDR;
	clocksource_sn2.mult = clocksource_hz2mult(sn_rtc_cycles_per_second,
							clocksource_sn2.shift);
	clocksource_register(&clocksource_sn2);

	ia64_udelay = &ia64_sn_udelay;
}