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/*
* linux/arch/arm26/kernel/time.c
*
* Copyright (C) 1991, 1992, 1995 Linus Torvalds
* Modifications for ARM (C) 1994-2001 Russell King
* Mods for ARM26 (C) 2003 Ian Molton
*
* 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.
*
* This file contains the ARM-specific time handling details:
* reading the RTC at bootup, etc...
*
* 1994-07-02 Alan Modra
* fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
* 1998-12-20 Updated NTP code according to technical memorandum Jan '96
* "A Kernel Model for Precision Timekeeping" by Dave Mills
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/time.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/timex.h>
#include <linux/errno.h>
#include <linux/profile.h>
#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/ioc.h>
extern unsigned long wall_jiffies;
/* this needs a better home */
DEFINE_SPINLOCK(rtc_lock);
/* change this if you have some constant time drift */
#define USECS_PER_JIFFY (1000000/HZ)
static int dummy_set_rtc(void)
{
return 0;
}
/*
* hook for setting the RTC's idea of the current time.
*/
int (*set_rtc)(void) = dummy_set_rtc;
/*
* Get time offset based on IOCs timer.
* FIXME - if this is called with interrutps off, why the shennanigans
* below ?
*/
static unsigned long 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;
}
/*
* Scheduler clock - returns current time in nanosec units.
*/
unsigned long long sched_clock(void)
{
return (unsigned long long)jiffies * (1000000000 / HZ);
}
static unsigned long next_rtc_update;
/*
* If we have an externally synchronized linux clock, then update
* CMOS clock accordingly every ~11 minutes. set_rtc() has to be
* called as close as possible to 500 ms before the new second
* starts.
*/
static inline void do_set_rtc(void)
{
if (!ntp_synced() || set_rtc == NULL)
return;
//FIXME - timespec.tv_sec is a time_t not unsigned long
if (next_rtc_update &&
time_before((unsigned long)xtime.tv_sec, next_rtc_update))
return;
if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) &&
xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1))
return;
if (set_rtc())
/*
* rtc update failed. Try again in 60s
*/
next_rtc_update = xtime.tv_sec + 60;
else
next_rtc_update = xtime.tv_sec + 660;
}
#define do_leds()
void do_gettimeofday(struct timeval *tv)
{
unsigned long flags;
unsigned long seq;
unsigned long usec, sec, lost;
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
usec = gettimeoffset();
lost = jiffies - wall_jiffies;
if (lost)
usec += lost * USECS_PER_JIFFY;
sec = xtime.tv_sec;
usec += xtime.tv_nsec / 1000;
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
/* usec may have gone up a lot: be safe */
while (usec >= 1000000) {
usec -= 1000000;
sec++;
}
tv->tv_sec = sec;
tv->tv_usec = usec;
}
EXPORT_SYMBOL(do_gettimeofday);
int do_settimeofday(struct timespec *tv)
{
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
write_seqlock_irq(&xtime_lock);
/*
* This is revolting. We need to set "xtime" correctly. However, the
* value in this location is the value at the most recent update of
* wall time. Discover what correction gettimeofday() would have
* done, and then undo it!
*/
tv->tv_nsec -= 1000 * (gettimeoffset() +
(jiffies - wall_jiffies) * USECS_PER_JIFFY);
while (tv->tv_nsec < 0) {
tv->tv_nsec += NSEC_PER_SEC;
tv->tv_sec--;
}
xtime.tv_sec = tv->tv_sec;
xtime.tv_nsec = tv->tv_nsec;
ntp_clear();
write_sequnlock_irq(&xtime_lock);
clock_was_set();
return 0;
}
EXPORT_SYMBOL(do_settimeofday);
static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
do_timer(regs);
#ifndef CONFIG_SMP
update_process_times(user_mode(regs));
#endif
do_set_rtc(); //FIME - EVERY timer IRQ?
profile_tick(CPU_PROFILING, regs);
return IRQ_HANDLED; //FIXME - is this right?
}
static struct irqaction timer_irq = {
.name = "timer",
.flags = SA_INTERRUPT,
.handler = timer_interrupt,
};
extern void ioctime_init(void);
/*
* Set up timer interrupt.
*/
void __init time_init(void)
{
ioc_writeb(LATCH & 255, IOC_T0LTCHL);
ioc_writeb(LATCH >> 8, IOC_T0LTCHH);
ioc_writeb(0, IOC_T0GO);
setup_irq(IRQ_TIMER, &timer_irq);
}
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