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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/sched.h> /* just for sched_clock() - funny that */
#include <linux/timex.h>
#include <linux/clockchips.h>
#include <asm/mach/time.h>
#include <asm/sched_clock.h>
#include <mach/hardware.h>
/*
* This is the SA11x0 sched_clock implementation.
*/
static DEFINE_CLOCK_DATA(cd);
/*
* Constants generated by clocks_calc_mult_shift(m, s, 3.6864MHz,
* NSEC_PER_SEC, 60).
* This gives a resolution of about 271ns and a wrap period of about 19min.
*/
#define SC_MULT 2275555556u
#define SC_SHIFT 23
unsigned long long notrace sched_clock(void)
{
u32 cyc = OSCR;
return cyc_to_fixed_sched_clock(&cd, cyc, (u32)~0, SC_MULT, SC_SHIFT);
}
static void notrace sa1100_update_sched_clock(void)
{
u32 cyc = OSCR;
update_sched_clock(&cd, cyc, (u32)~0);
}
#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. */
OIER &= ~OIER_E0;
OSSR = OSSR_M0;
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;
OIER |= OIER_E0;
next = OSCR + delta;
OSMR0 = next;
oscr = 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:
OIER &= ~OIER_E0;
OSSR = OSSR_M0;
break;
case CLOCK_EVT_MODE_RESUME:
case CLOCK_EVT_MODE_PERIODIC:
break;
}
}
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,
};
static cycle_t sa1100_read_oscr(struct clocksource *s)
{
return OSCR;
}
static struct clocksource cksrc_sa1100_oscr = {
.name = "oscr",
.rating = 200,
.read = sa1100_read_oscr,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static struct irqaction sa1100_timer_irq = {
.name = "ost0",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = sa1100_ost0_interrupt,
.dev_id = &ckevt_sa1100_osmr0,
};
static void __init sa1100_timer_init(void)
{
OIER = 0;
OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3;
init_fixed_sched_clock(&cd, sa1100_update_sched_clock, 32,
3686400, SC_MULT, SC_SHIFT);
clockevents_calc_mult_shift(&ckevt_sa1100_osmr0, 3686400, 4);
ckevt_sa1100_osmr0.max_delta_ns =
clockevent_delta2ns(0x7fffffff, &ckevt_sa1100_osmr0);
ckevt_sa1100_osmr0.min_delta_ns =
clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_sa1100_osmr0) + 1;
ckevt_sa1100_osmr0.cpumask = cpumask_of(0);
setup_irq(IRQ_OST0, &sa1100_timer_irq);
clocksource_register_hz(&cksrc_sa1100_oscr, CLOCK_TICK_RATE);
clockevents_register_device(&ckevt_sa1100_osmr0);
}
#ifdef CONFIG_PM
unsigned long osmr[4], oier;
static void sa1100_timer_suspend(void)
{
osmr[0] = OSMR0;
osmr[1] = OSMR1;
osmr[2] = OSMR2;
osmr[3] = OSMR3;
oier = OIER;
}
static void sa1100_timer_resume(void)
{
OSSR = 0x0f;
OSMR0 = osmr[0];
OSMR1 = osmr[1];
OSMR2 = osmr[2];
OSMR3 = osmr[3];
OIER = oier;
/*
* OSMR0 is the system timer: make sure OSCR is sufficiently behind
*/
OSCR = OSMR0 - LATCH;
}
#else
#define sa1100_timer_suspend NULL
#define sa1100_timer_resume NULL
#endif
struct sys_timer sa1100_timer = {
.init = sa1100_timer_init,
.suspend = sa1100_timer_suspend,
.resume = sa1100_timer_resume,
};
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