time.c
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/*
* linux/arch/arm/mach-sa1100/time.c
*
* Copyright (C) 1998 Deborah Wallach.
* Twiddles (C) 1999 Hugo Fiennes <hugo@empeg.com>
*
* 2000/03/29 (C) Nicolas Pitre <nico@fluxnic.net>
* Rewritten: big cleanup, much simpler, better HZ accuracy.
*
*/
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/timex.h>
#include <linux/clockchips.h>
#include <linux/sched_clock.h>
#include <asm/mach/time.h>
#include <mach/hardware.h>
#include <mach/irqs.h>
static u64 notrace sa1100_read_sched_clock(void)
{
return readl_relaxed(OSCR);
}
#define MIN_OSCR_DELTA 2
static irqreturn_t sa1100_ost0_interrupt(int irq, void *dev_id)
{
struct clock_event_device *c = dev_id;
/* Disarm the compare/match, signal the event. */
writel_relaxed(readl_relaxed(OIER) & ~OIER_E0, OIER);
writel_relaxed(OSSR_M0, OSSR);
c->event_handler(c);
return IRQ_HANDLED;
}
static int
sa1100_osmr0_set_next_event(unsigned long delta, struct clock_event_device *c)
{
unsigned long next, oscr;
writel_relaxed(readl_relaxed(OIER) | OIER_E0, OIER);
next = readl_relaxed(OSCR) + delta;
writel_relaxed(next, OSMR0);
oscr = readl_relaxed(OSCR);
return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
}
static void
sa1100_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *c)
{
switch (mode) {
case CLOCK_EVT_MODE_ONESHOT:
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
writel_relaxed(readl_relaxed(OIER) & ~OIER_E0, OIER);
writel_relaxed(OSSR_M0, OSSR);
break;
case CLOCK_EVT_MODE_RESUME:
case CLOCK_EVT_MODE_PERIODIC:
break;
}
}
#ifdef CONFIG_PM
unsigned long osmr[4], oier;
static void sa1100_timer_suspend(struct clock_event_device *cedev)
{
osmr[0] = readl_relaxed(OSMR0);
osmr[1] = readl_relaxed(OSMR1);
osmr[2] = readl_relaxed(OSMR2);
osmr[3] = readl_relaxed(OSMR3);
oier = readl_relaxed(OIER);
}
static void sa1100_timer_resume(struct clock_event_device *cedev)
{
writel_relaxed(0x0f, OSSR);
writel_relaxed(osmr[0], OSMR0);
writel_relaxed(osmr[1], OSMR1);
writel_relaxed(osmr[2], OSMR2);
writel_relaxed(osmr[3], OSMR3);
writel_relaxed(oier, OIER);
/*
* OSMR0 is the system timer: make sure OSCR is sufficiently behind
*/
writel_relaxed(OSMR0 - LATCH, OSCR);
}
#else
#define sa1100_timer_suspend NULL
#define sa1100_timer_resume NULL
#endif
static struct clock_event_device ckevt_sa1100_osmr0 = {
.name = "osmr0",
.features = CLOCK_EVT_FEAT_ONESHOT,
.rating = 200,
.set_next_event = sa1100_osmr0_set_next_event,
.set_mode = sa1100_osmr0_set_mode,
.suspend = sa1100_timer_suspend,
.resume = sa1100_timer_resume,
};
static struct irqaction sa1100_timer_irq = {
.name = "ost0",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = sa1100_ost0_interrupt,
.dev_id = &ckevt_sa1100_osmr0,
};
void __init sa1100_timer_init(void)
{
writel_relaxed(0, OIER);
writel_relaxed(OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3, OSSR);
sched_clock_register(sa1100_read_sched_clock, 32, 3686400);
ckevt_sa1100_osmr0.cpumask = cpumask_of(0);
setup_irq(IRQ_OST0, &sa1100_timer_irq);
clocksource_mmio_init(OSCR, "oscr", CLOCK_TICK_RATE, 200, 32,
clocksource_mmio_readl_up);
clockevents_config_and_register(&ckevt_sa1100_osmr0, 3686400,
MIN_OSCR_DELTA * 2, 0x7fffffff);
}