/*
|
* 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 <linux/io.h>
|
|
#include <mach/hardware.h>
|
#include <asm/hardware/ioc.h>
|
|
#include <asm/mach/time.h>
|
|
#define RPC_CLOCK_FREQ 2000000
|
#define RPC_LATCH DIV_ROUND_CLOSEST(RPC_CLOCK_FREQ, HZ)
|
|
static u32 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 -= RPC_LATCH;
|
} else if (count2 > count1) {
|
/*
|
* We have just had another interrupt between reading
|
* count1 and count2.
|
*/
|
offset -= RPC_LATCH;
|
}
|
|
offset = (RPC_LATCH - offset) * (tick_nsec / 1000);
|
return DIV_ROUND_CLOSEST(offset, RPC_LATCH) * 1000;
|
}
|
|
void __init ioctime_init(void)
|
{
|
ioc_writeb(RPC_LATCH & 255, IOC_T0LTCHL);
|
ioc_writeb(RPC_LATCH >> 8, IOC_T0LTCHH);
|
ioc_writeb(0, IOC_T0GO);
|
}
|
|
static irqreturn_t
|
ioc_timer_interrupt(int irq, void *dev_id)
|
{
|
timer_tick();
|
return IRQ_HANDLED;
|
}
|
|
static struct irqaction ioc_timer_irq = {
|
.name = "timer",
|
.handler = ioc_timer_interrupt
|
};
|
|
/*
|
* Set up timer interrupt.
|
*/
|
void __init ioc_timer_init(void)
|
{
|
arch_gettimeoffset = ioc_timer_gettimeoffset;
|
ioctime_init();
|
setup_irq(IRQ_TIMER0, &ioc_timer_irq);
|
}
|
