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/*
* linux/arch/arm/mach-imx/time.c
*
* Copyright (C) 2000-2001 Deep Blue Solutions
* Copyright (C) 2002 Shane Nay (shane@minirl.com)
*
* 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/sched.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/time.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/leds.h>
#include <asm/irq.h>
#include <asm/mach/time.h>
/* Use timer 1 as system timer */
#define TIMER_BASE IMX_TIM1_BASE
/*
* Returns number of us since last clock interrupt. Note that interrupts
* will have been disabled by do_gettimeoffset()
*/
static unsigned long imx_gettimeoffset(void)
{
unsigned long ticks;
/*
* Get the current number of ticks. Note that there is a race
* condition between us reading the timer and checking for
* an interrupt. We get around this by ensuring that the
* counter has not reloaded between our two reads.
*/
ticks = IMX_TCN(TIMER_BASE);
/*
* Interrupt pending? If so, we've reloaded once already.
*/
if (IMX_TSTAT(TIMER_BASE) & TSTAT_COMP)
ticks += LATCH;
/*
* Convert the ticks to usecs
*/
return (1000000 / CLK32) * ticks;
}
/*
* IRQ handler for the timer
*/
static irqreturn_t
imx_timer_interrupt(int irq, void *dev_id)
{
write_seqlock(&xtime_lock);
/* clear the interrupt */
if (IMX_TSTAT(TIMER_BASE))
IMX_TSTAT(TIMER_BASE) = 0;
timer_tick();
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static struct irqaction imx_timer_irq = {
.name = "i.MX Timer Tick",
.flags = IRQF_DISABLED | IRQF_TIMER,
.handler = imx_timer_interrupt,
};
/*
* Set up timer interrupt, and return the current time in seconds.
*/
static void __init imx_timer_init(void)
{
/*
* Initialise to a known state (all timers off, and timing reset)
*/
IMX_TCTL(TIMER_BASE) = 0;
IMX_TPRER(TIMER_BASE) = 0;
IMX_TCMP(TIMER_BASE) = LATCH - 1;
IMX_TCTL(TIMER_BASE) = TCTL_CLK_32 | TCTL_IRQEN | TCTL_TEN;
/*
* Make irqs happen for the system timer
*/
setup_irq(TIM1_INT, &imx_timer_irq);
}
struct sys_timer imx_timer = {
.init = imx_timer_init,
.offset = imx_gettimeoffset,
};
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