![Alexey Dobriyan](/assets/img/avatar_default.png)
Use attribute(weak). Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
211 lines
5.1 KiB
C
211 lines
5.1 KiB
C
/*
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* linux/arch/arm26/kernel/time.c
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*
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* Copyright (C) 1991, 1992, 1995 Linus Torvalds
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* Modifications for ARM (C) 1994-2001 Russell King
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* Mods for ARM26 (C) 2003 Ian Molton
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This file contains the ARM-specific time handling details:
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* reading the RTC at bootup, etc...
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*
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* 1994-07-02 Alan Modra
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* fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
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* 1998-12-20 Updated NTP code according to technical memorandum Jan '96
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* "A Kernel Model for Precision Timekeeping" by Dave Mills
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/interrupt.h>
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#include <linux/time.h>
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#include <linux/init.h>
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#include <linux/smp.h>
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#include <linux/timex.h>
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#include <linux/errno.h>
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#include <linux/profile.h>
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#include <asm/hardware.h>
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#include <asm/io.h>
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#include <asm/irq.h>
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#include <asm/ioc.h>
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/* this needs a better home */
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DEFINE_SPINLOCK(rtc_lock);
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/* change this if you have some constant time drift */
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#define USECS_PER_JIFFY (1000000/HZ)
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static int dummy_set_rtc(void)
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{
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return 0;
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}
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/*
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* hook for setting the RTC's idea of the current time.
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*/
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int (*set_rtc)(void) = dummy_set_rtc;
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/*
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* Get time offset based on IOCs timer.
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* FIXME - if this is called with interrutps off, why the shennanigans
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* below ?
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*/
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static unsigned long gettimeoffset(void)
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{
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unsigned int count1, count2, status;
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long offset;
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ioc_writeb (0, IOC_T0LATCH);
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barrier ();
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count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
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barrier ();
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status = ioc_readb(IOC_IRQREQA);
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barrier ();
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ioc_writeb (0, IOC_T0LATCH);
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barrier ();
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count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
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offset = count2;
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if (count2 < count1) {
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/*
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* We have not had an interrupt between reading count1
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* and count2.
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*/
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if (status & (1 << 5))
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offset -= LATCH;
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} else if (count2 > count1) {
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/*
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* We have just had another interrupt between reading
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* count1 and count2.
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*/
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offset -= LATCH;
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}
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offset = (LATCH - offset) * (tick_nsec / 1000);
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return (offset + LATCH/2) / LATCH;
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}
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static unsigned long next_rtc_update;
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/*
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* If we have an externally synchronized linux clock, then update
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* CMOS clock accordingly every ~11 minutes. set_rtc() has to be
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* called as close as possible to 500 ms before the new second
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* starts.
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*/
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static inline void do_set_rtc(void)
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{
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if (!ntp_synced() || set_rtc == NULL)
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return;
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//FIXME - timespec.tv_sec is a time_t not unsigned long
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if (next_rtc_update &&
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time_before((unsigned long)xtime.tv_sec, next_rtc_update))
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return;
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if (xtime.tv_nsec < 500000000 - ((unsigned) tick_nsec >> 1) &&
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xtime.tv_nsec >= 500000000 + ((unsigned) tick_nsec >> 1))
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return;
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if (set_rtc())
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/*
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* rtc update failed. Try again in 60s
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*/
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next_rtc_update = xtime.tv_sec + 60;
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else
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next_rtc_update = xtime.tv_sec + 660;
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}
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#define do_leds()
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void do_gettimeofday(struct timeval *tv)
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{
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unsigned long flags;
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unsigned long seq;
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unsigned long usec, sec;
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do {
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seq = read_seqbegin_irqsave(&xtime_lock, flags);
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usec = gettimeoffset();
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sec = xtime.tv_sec;
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usec += xtime.tv_nsec / 1000;
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} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
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/* usec may have gone up a lot: be safe */
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while (usec >= 1000000) {
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usec -= 1000000;
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sec++;
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}
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tv->tv_sec = sec;
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tv->tv_usec = usec;
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}
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EXPORT_SYMBOL(do_gettimeofday);
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int do_settimeofday(struct timespec *tv)
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{
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if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
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return -EINVAL;
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write_seqlock_irq(&xtime_lock);
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/*
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* This is revolting. We need to set "xtime" correctly. However, the
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* value in this location is the value at the most recent update of
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* wall time. Discover what correction gettimeofday() would have
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* done, and then undo it!
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*/
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tv->tv_nsec -= 1000 * gettimeoffset();
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while (tv->tv_nsec < 0) {
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tv->tv_nsec += NSEC_PER_SEC;
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tv->tv_sec--;
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}
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xtime.tv_sec = tv->tv_sec;
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xtime.tv_nsec = tv->tv_nsec;
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ntp_clear();
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write_sequnlock_irq(&xtime_lock);
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clock_was_set();
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return 0;
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}
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EXPORT_SYMBOL(do_settimeofday);
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static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
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{
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do_timer(1);
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#ifndef CONFIG_SMP
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update_process_times(user_mode(regs));
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#endif
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do_set_rtc(); //FIME - EVERY timer IRQ?
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profile_tick(CPU_PROFILING, regs);
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return IRQ_HANDLED; //FIXME - is this right?
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}
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static struct irqaction timer_irq = {
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.name = "timer",
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.flags = IRQF_DISABLED,
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.handler = timer_interrupt,
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};
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extern void ioctime_init(void);
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/*
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* Set up timer interrupt.
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*/
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void __init time_init(void)
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{
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ioc_writeb(LATCH & 255, IOC_T0LTCHL);
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ioc_writeb(LATCH >> 8, IOC_T0LTCHH);
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ioc_writeb(0, IOC_T0GO);
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setup_irq(IRQ_TIMER, &timer_irq);
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}
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