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/*
* linux/arch/arm/common/time-acorn.c
*
* Copyright (c) 1996-2000 Russell King.
*
* 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.
*
* Changelog:
* 24-Sep-1996 RMK Created
* 10-Oct-1996 RMK Brought up to date with arch-sa110eval
* 04-Dec-1997 RMK Updated for new arch/arm/time.c
* 13=Jun-2004 DS Moved to arch/arm/common b/c shared w/CLPS7500
*/
#include <linux/timex.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/hardware/ioc.h>
#include <asm/mach/time.h>
unsigned long ioc_timer_gettimeoffset(void)
{
unsigned int count1, count2, status;
long offset;
ioc_writeb (0, IOC_T0LATCH);
barrier ();
count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
barrier ();
status = ioc_readb(IOC_IRQREQA);
barrier ();
ioc_writeb (0, IOC_T0LATCH);
barrier ();
count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
offset = count2;
if (count2 < count1) {
/*
* We have not had an interrupt between reading count1
* and count2.
*/
if (status & (1 << 5))
offset -= LATCH;
} else if (count2 > count1) {
/*
* We have just had another interrupt between reading
* count1 and count2.
*/
offset -= LATCH;
}
offset = (LATCH - offset) * (tick_nsec / 1000);
return (offset + LATCH/2) / LATCH;
}
void __init ioctime_init(void)
{
ioc_writeb(LATCH & 255, IOC_T0LTCHL);
ioc_writeb(LATCH >> 8, IOC_T0LTCHH);
ioc_writeb(0, IOC_T0GO);
}
static irqreturn_t
ioc_timer_interrupt(int irq, void *dev_id)
{
write_seqlock(&xtime_lock);
timer_tick();
write_sequnlock(&xtime_lock);
return IRQ_HANDLED;
}
static struct irqaction ioc_timer_irq = {
.name = "timer",
.flags = IRQF_DISABLED,
.handler = ioc_timer_interrupt
};
/*
* Set up timer interrupt.
*/
static void __init ioc_timer_init(void)
{
ioctime_init();
setup_irq(IRQ_TIMER, &ioc_timer_irq);
}
struct sys_timer ioc_timer = {
.init = ioc_timer_init,
.offset = ioc_timer_gettimeoffset,
};
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