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/*
* arch/arm/mach-pxa/time.c
*
* PXA clocksource, clockevents, and OST interrupt handlers.
* Copyright (c) 2007 by Bill Gatliff <bgat@billgatliff.com>.
*
* Derived from Nicolas Pitre's PXA timer handler Copyright (c) 2001
* by MontaVista Software, Inc. (Nico, your code rocks!)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/clockchips.h>
#include <linux/sched.h>
#include <linux/cnt32_to_63.h>
#include <asm/div64.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
#include <mach/regs-ost.h>
/*
* This is PXA's sched_clock implementation. This has a resolution
* of at least 308 ns and a maximum value of 208 days.
*
* The return value is guaranteed to be monotonic in that range as
* long as there is always less than 582 seconds between successive
* calls to sched_clock() which should always be the case in practice.
*/
#define OSCR2NS_SCALE_FACTOR 10
static unsigned long oscr2ns_scale;
static void __init set_oscr2ns_scale(unsigned long oscr_rate)
{
unsigned long long v = 1000000000ULL << OSCR2NS_SCALE_FACTOR;
do_div(v, oscr_rate);
oscr2ns_scale = v;
/*
* We want an even value to automatically clear the top bit
* returned by cnt32_to_63() without an additional run time
* instruction. So if the LSB is 1 then round it up.
*/
if (oscr2ns_scale & 1)
oscr2ns_scale++;
}
unsigned long long sched_clock(void)
{
unsigned long long v = cnt32_to_63(OSCR);
return (v * oscr2ns_scale) >> OSCR2NS_SCALE_FACTOR;
}
#define MIN_OSCR_DELTA 16
static irqreturn_t
pxa_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
pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev)
{
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
pxa_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *dev)
{
switch (mode) {
case CLOCK_EVT_MODE_ONESHOT:
OIER &= ~OIER_E0;
OSSR = OSSR_M0;
break;
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
/* initializing, released, or preparing for suspend */
OIER &= ~OIER_E0;
OSSR = OSSR_M0;
break;
case CLOCK_EVT_MODE_RESUME:
case CLOCK_EVT_MODE_PERIODIC:
break;
}
}
static struct clock_event_device ckevt_pxa_osmr0 = {
.name = "osmr0",
.features = CLOCK_EVT_FEAT_ONESHOT,
.shift = 32,
.rating = 200,
.set_next_event = pxa_osmr0_set_next_event,
.set_mode = pxa_osmr0_set_mode,
};
static cycle_t pxa_read_oscr(struct clocksource *cs)
{
return OSCR;
}
static struct clocksource cksrc_pxa_oscr0 = {
.name = "oscr0",
.rating = 200,
.read = pxa_read_oscr,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static struct irqaction pxa_ost0_irq = {
.name = "ost0",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = pxa_ost0_interrupt,
.dev_id = &ckevt_pxa_osmr0,
};
static void __init pxa_timer_init(void)
{
unsigned long clock_tick_rate = get_clock_tick_rate();
OIER = 0;
OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3;
set_oscr2ns_scale(clock_tick_rate);
ckevt_pxa_osmr0.mult =
div_sc(clock_tick_rate, NSEC_PER_SEC, ckevt_pxa_osmr0.shift);
ckevt_pxa_osmr0.max_delta_ns =
clockevent_delta2ns(0x7fffffff, &ckevt_pxa_osmr0);
ckevt_pxa_osmr0.min_delta_ns =
clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_pxa_osmr0) + 1;
ckevt_pxa_osmr0.cpumask = cpumask_of(0);
setup_irq(IRQ_OST0, &pxa_ost0_irq);
clocksource_register_hz(&cksrc_pxa_oscr0, clock_tick_rate);
clockevents_register_device(&ckevt_pxa_osmr0);
}
#ifdef CONFIG_PM
static unsigned long osmr[4], oier, oscr;
static void pxa_timer_suspend(void)
{
osmr[0] = OSMR0;
osmr[1] = OSMR1;
osmr[2] = OSMR2;
osmr[3] = OSMR3;
oier = OIER;
oscr = OSCR;
}
static void pxa_timer_resume(void)
{
/*
* Ensure that we have at least MIN_OSCR_DELTA between match
* register 0 and the OSCR, to guarantee that we will receive
* the one-shot timer interrupt. We adjust OSMR0 in preference
* to OSCR to guarantee that OSCR is monotonically incrementing.
*/
if (osmr[0] - oscr < MIN_OSCR_DELTA)
osmr[0] += MIN_OSCR_DELTA;
OSMR0 = osmr[0];
OSMR1 = osmr[1];
OSMR2 = osmr[2];
OSMR3 = osmr[3];
OIER = oier;
OSCR = oscr;
}
#else
#define pxa_timer_suspend NULL
#define pxa_timer_resume NULL
#endif
struct sys_timer pxa_timer = {
.init = pxa_timer_init,
.suspend = pxa_timer_suspend,
.resume = pxa_timer_resume,
};
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