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/*
* arch/arm/mach-pxa/time.c
*
* Author: Nicolas Pitre
* Created: Jun 15, 2001
* Copyright: MontaVista Software Inc.
*
* 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/delay.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/clocksource.h>
#include <asm/system.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/leds.h>
#include <asm/irq.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
#include <asm/arch/pxa-regs.h>
static int pxa_set_rtc(void)
{
unsigned long current_time = xtime.tv_sec;
if (RTSR & RTSR_ALE) {
/* make sure not to forward the clock over an alarm */
unsigned long alarm = RTAR;
if (current_time >= alarm && alarm >= RCNR)
return -ERESTARTSYS;
}
RCNR = current_time;
return 0;
}
#ifdef CONFIG_NO_IDLE_HZ
static unsigned long initial_match;
static int match_posponed;
#endif
static irqreturn_t
pxa_timer_interrupt(int irq, void *dev_id)
{
int next_match;
write_seqlock(&xtime_lock);
#ifdef CONFIG_NO_IDLE_HZ
if (match_posponed) {
match_posponed = 0;
OSMR0 = initial_match;
}
#endif
/* Loop until we get ahead of the free running timer.
* This ensures an exact clock tick count and time accuracy.
* Since IRQs are disabled at this point, coherence between
* lost_ticks(updated in do_timer()) and the match reg value is
* ensured, hence we can use do_gettimeofday() from interrupt
* handlers.
*
* HACK ALERT: it seems that the PXA timer regs aren't updated right
* away in all cases when a write occurs. We therefore compare with
* 8 instead of 0 in the while() condition below to avoid missing a
* match if OSCR has already reached the next OSMR value.
* Experience has shown that up to 6 ticks are needed to work around
* this problem, but let's use 8 to be conservative. Note that this
* affect things only when the timer IRQ has been delayed by nearly
* exactly one tick period which should be a pretty rare event.
*/
do {
timer_tick();
OSSR = OSSR_M0; /* Clear match on timer 0 */
next_match = (OSMR0 += LATCH);
} while( (signed long)(next_match - OSCR) <= 8 );
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static struct irqaction pxa_timer_irq = {
.name = "PXA Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = pxa_timer_interrupt,
};
static cycle_t pxa_get_cycles(void)
{
return OSCR;
}
static struct clocksource clocksource_pxa = {
.name = "pxa_timer",
.rating = 200,
.read = pxa_get_cycles,
.mask = CLOCKSOURCE_MASK(32),
.shift = 20,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static void __init pxa_timer_init(void)
{
struct timespec tv;
unsigned long flags;
set_rtc = pxa_set_rtc;
OIER = 0; /* disable any timer interrupts */
OSSR = 0xf; /* clear status on all timers */
setup_irq(IRQ_OST0, &pxa_timer_irq);
local_irq_save(flags);
OIER = OIER_E0; /* enable match on timer 0 to cause interrupts */
OSMR0 = OSCR + LATCH; /* set initial match */
local_irq_restore(flags);
/*
* OSCR runs continuously on PXA and is not written to,
* so we can use it as clock source directly.
*/
clocksource_pxa.mult =
clocksource_hz2mult(CLOCK_TICK_RATE, clocksource_pxa.shift);
clocksource_register(&clocksource_pxa);
}
#ifdef CONFIG_NO_IDLE_HZ
static int pxa_dyn_tick_enable_disable(void)
{
/* nothing to do */
return 0;
}
static void pxa_dyn_tick_reprogram(unsigned long ticks)
{
if (ticks > 1) {
initial_match = OSMR0;
OSMR0 = initial_match + ticks * LATCH;
match_posponed = 1;
}
}
static irqreturn_t
pxa_dyn_tick_handler(int irq, void *dev_id)
{
if (match_posponed) {
match_posponed = 0;
OSMR0 = initial_match;
if ( (signed long)(initial_match - OSCR) <= 8 )
return pxa_timer_interrupt(irq, dev_id);
}
return IRQ_NONE;
}
static struct dyn_tick_timer pxa_dyn_tick = {
.enable = pxa_dyn_tick_enable_disable,
.disable = pxa_dyn_tick_enable_disable,
.reprogram = pxa_dyn_tick_reprogram,
.handler = pxa_dyn_tick_handler,
};
#endif
#ifdef CONFIG_PM
static unsigned long osmr[4], oier;
static void pxa_timer_suspend(void)
{
osmr[0] = OSMR0;
osmr[1] = OSMR1;
osmr[2] = OSMR2;
osmr[3] = OSMR3;
oier = OIER;
}
static void pxa_timer_resume(void)
{
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 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,
#ifdef CONFIG_NO_IDLE_HZ
.dyn_tick = &pxa_dyn_tick,
#endif
};
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