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/*
* linux/arch/arm/kernel/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
*/
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/hardware/ioc.h>
extern unsigned long (*gettimeoffset)(void);
static unsigned long ioctime_gettimeoffset(void)
{
unsigned int count1, count2, status1, status2;
unsigned long offset = 0;
status1 = ioc_readb(IOC_IRQREQA);
barrier ();
ioc_writeb (0, IOC_T0LATCH);
barrier ();
count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
barrier ();
status2 = ioc_readb(IOC_IRQREQA);
barrier ();
ioc_writeb (0, IOC_T0LATCH);
barrier ();
count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
if (count2 < count1) {
/*
* This means that we haven't just had an interrupt
* while reading into status2.
*/
if (status2 & (1 << 5))
offset = tick;
count1 = count2;
} else if (count2 > count1) {
/*
* We have just had another interrupt while reading
* status2.
*/
offset += tick;
count1 = count2;
}
count1 = LATCH - count1;
/*
* count1 = number of clock ticks since last interrupt
*/
offset += count1 * tick / LATCH;
return offset;
}
void __init ioctime_init(void)
{
ioc_writeb(LATCH & 255, IOC_T0LTCHL);
ioc_writeb(LATCH >> 8, IOC_T0LTCHH);
ioc_writeb(0, IOC_T0GO);
gettimeoffset = ioctime_gettimeoffset;
}
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