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/*
* linux/arch/arm/mach-at91/at91sam926x_time.c
*
* Copyright (C) 2005-2006 M. Amine SAYA, ATMEL Rousset, France
* Revision 2005 M. Nicolas Diremdjian, ATMEL Rousset, France
*
* 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/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/mach/time.h>
#include <asm/arch/at91_pit.h>
#define PIT_CPIV(x) ((x) & AT91_PIT_CPIV)
#define PIT_PICNT(x) (((x) & AT91_PIT_PICNT) >> 20)
/*
* Returns number of microseconds since last timer interrupt. Note that interrupts
* will have been disabled by do_gettimeofday()
* 'LATCH' is hwclock ticks (see CLOCK_TICK_RATE in timex.h) per jiffy.
*/
static unsigned long at91sam926x_gettimeoffset(void)
{
unsigned long elapsed;
unsigned long t = at91_sys_read(AT91_PIT_PIIR);
elapsed = (PIT_PICNT(t) * LATCH) + PIT_CPIV(t); /* hardware clock cycles */
return (unsigned long)(elapsed * jiffies_to_usecs(1)) / LATCH;
}
/*
* IRQ handler for the timer.
*/
static irqreturn_t at91sam926x_timer_interrupt(int irq, void *dev_id)
{
volatile long nr_ticks;
if (at91_sys_read(AT91_PIT_SR) & AT91_PIT_PITS) { /* This is a shared interrupt */
write_seqlock(&xtime_lock);
/* Get number to ticks performed before interrupt and clear PIT interrupt */
nr_ticks = PIT_PICNT(at91_sys_read(AT91_PIT_PIVR));
do {
timer_tick();
nr_ticks--;
} while (nr_ticks);
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
} else
return IRQ_NONE; /* not handled */
}
static struct irqaction at91sam926x_timer_irq = {
.name = "at91_tick",
.flags = IRQF_SHARED | IRQF_DISABLED | IRQF_TIMER,
.handler = at91sam926x_timer_interrupt
};
void at91sam926x_timer_reset(void)
{
/* Disable timer */
at91_sys_write(AT91_PIT_MR, 0);
/* Clear any pending interrupts */
(void) at91_sys_read(AT91_PIT_PIVR);
/* Set Period Interval timer and enable its interrupt */
at91_sys_write(AT91_PIT_MR, (LATCH & AT91_PIT_PIV) | AT91_PIT_PITIEN | AT91_PIT_PITEN);
}
/*
* Set up timer interrupt.
*/
void __init at91sam926x_timer_init(void)
{
/* Initialize and enable the timer */
at91sam926x_timer_reset();
/* Make IRQs happen for the system timer. */
setup_irq(AT91_ID_SYS, &at91sam926x_timer_irq);
}
#ifdef CONFIG_PM
static void at91sam926x_timer_suspend(void)
{
/* Disable timer */
at91_sys_write(AT91_PIT_MR, 0);
}
#else
#define at91sam926x_timer_suspend NULL
#endif
struct sys_timer at91sam926x_timer = {
.init = at91sam926x_timer_init,
.offset = at91sam926x_gettimeoffset,
.suspend = at91sam926x_timer_suspend,
.resume = at91sam926x_timer_reset,
};
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