mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-21 18:11:39 +00:00
d11d5794e0
The code that used to be in do_slow_gettimeoffset() that relied on the IRR bit of the master 8259A PIC for IRQ0 to check the state of the output timer 0 of the PIT is no longer there. As a result, there is no need to use the POLL command to acknowledge the timer interrupt in the "8259A Virtual Wire", except for the NMI watchdog when the i82489DX APIC is used (this is because this particular APIC treats NMIs as level-triggered and keeping the input asserted would keep motherboard NMI sources held off for too long). Remove the unneeded bits and adjust comments accordingly. Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>
137 lines
4.1 KiB
C
137 lines
4.1 KiB
C
/*
|
|
* Copyright (C) 1991, 1992, 1995 Linus Torvalds
|
|
*
|
|
* This file contains the PC-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
|
|
* 1995-03-26 Markus Kuhn
|
|
* fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
|
|
* precision CMOS clock update
|
|
* 1996-05-03 Ingo Molnar
|
|
* fixed time warps in do_[slow|fast]_gettimeoffset()
|
|
* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
|
|
* "A Kernel Model for Precision Timekeeping" by Dave Mills
|
|
* 1998-09-05 (Various)
|
|
* More robust do_fast_gettimeoffset() algorithm implemented
|
|
* (works with APM, Cyrix 6x86MX and Centaur C6),
|
|
* monotonic gettimeofday() with fast_get_timeoffset(),
|
|
* drift-proof precision TSC calibration on boot
|
|
* (C. Scott Ananian <cananian@alumni.princeton.edu>, Andrew D.
|
|
* Balsa <andrebalsa@altern.org>, Philip Gladstone <philip@raptor.com>;
|
|
* ported from 2.0.35 Jumbo-9 by Michael Krause <m.krause@tu-harburg.de>).
|
|
* 1998-12-16 Andrea Arcangeli
|
|
* Fixed Jumbo-9 code in 2.1.131: do_gettimeofday was missing 1 jiffy
|
|
* because was not accounting lost_ticks.
|
|
* 1998-12-24 Copyright (C) 1998 Andrea Arcangeli
|
|
* Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
|
|
* serialize accesses to xtime/lost_ticks).
|
|
*/
|
|
|
|
#include <linux/init.h>
|
|
#include <linux/interrupt.h>
|
|
#include <linux/time.h>
|
|
#include <linux/mca.h>
|
|
|
|
#include <asm/arch_hooks.h>
|
|
#include <asm/hpet.h>
|
|
#include <asm/time.h>
|
|
|
|
#include "do_timer.h"
|
|
|
|
unsigned int cpu_khz; /* Detected as we calibrate the TSC */
|
|
EXPORT_SYMBOL(cpu_khz);
|
|
|
|
int timer_ack;
|
|
|
|
unsigned long profile_pc(struct pt_regs *regs)
|
|
{
|
|
unsigned long pc = instruction_pointer(regs);
|
|
|
|
#ifdef CONFIG_SMP
|
|
if (!v8086_mode(regs) && SEGMENT_IS_KERNEL_CODE(regs->cs) &&
|
|
in_lock_functions(pc)) {
|
|
#ifdef CONFIG_FRAME_POINTER
|
|
return *(unsigned long *)(regs->bp + 4);
|
|
#else
|
|
unsigned long *sp = (unsigned long *)®s->sp;
|
|
|
|
/* Return address is either directly at stack pointer
|
|
or above a saved flags. Eflags has bits 22-31 zero,
|
|
kernel addresses don't. */
|
|
if (sp[0] >> 22)
|
|
return sp[0];
|
|
if (sp[1] >> 22)
|
|
return sp[1];
|
|
#endif
|
|
}
|
|
#endif
|
|
return pc;
|
|
}
|
|
EXPORT_SYMBOL(profile_pc);
|
|
|
|
/*
|
|
* This is the same as the above, except we _also_ save the current
|
|
* Time Stamp Counter value at the time of the timer interrupt, so that
|
|
* we later on can estimate the time of day more exactly.
|
|
*/
|
|
irqreturn_t timer_interrupt(int irq, void *dev_id)
|
|
{
|
|
/* Keep nmi watchdog up to date */
|
|
per_cpu(irq_stat, smp_processor_id()).irq0_irqs++;
|
|
|
|
#ifdef CONFIG_X86_IO_APIC
|
|
if (timer_ack) {
|
|
/*
|
|
* Subtle, when I/O APICs are used we have to ack timer IRQ
|
|
* manually to deassert NMI lines for the watchdog if run
|
|
* on an 82489DX-based system.
|
|
*/
|
|
spin_lock(&i8259A_lock);
|
|
outb(0x0c, PIC_MASTER_OCW3);
|
|
/* Ack the IRQ; AEOI will end it automatically. */
|
|
inb(PIC_MASTER_POLL);
|
|
spin_unlock(&i8259A_lock);
|
|
}
|
|
#endif
|
|
|
|
do_timer_interrupt_hook();
|
|
|
|
if (MCA_bus) {
|
|
/* The PS/2 uses level-triggered interrupts. You can't
|
|
turn them off, nor would you want to (any attempt to
|
|
enable edge-triggered interrupts usually gets intercepted by a
|
|
special hardware circuit). Hence we have to acknowledge
|
|
the timer interrupt. Through some incredibly stupid
|
|
design idea, the reset for IRQ 0 is done by setting the
|
|
high bit of the PPI port B (0x61). Note that some PS/2s,
|
|
notably the 55SX, work fine if this is removed. */
|
|
|
|
u8 irq_v = inb_p( 0x61 ); /* read the current state */
|
|
outb_p( irq_v|0x80, 0x61 ); /* reset the IRQ */
|
|
}
|
|
|
|
return IRQ_HANDLED;
|
|
}
|
|
|
|
/* Duplicate of time_init() below, with hpet_enable part added */
|
|
void __init hpet_time_init(void)
|
|
{
|
|
if (!hpet_enable())
|
|
setup_pit_timer();
|
|
time_init_hook();
|
|
}
|
|
|
|
/*
|
|
* This is called directly from init code; we must delay timer setup in the
|
|
* HPET case as we can't make the decision to turn on HPET this early in the
|
|
* boot process.
|
|
*
|
|
* The chosen time_init function will usually be hpet_time_init, above, but
|
|
* in the case of virtual hardware, an alternative function may be substituted.
|
|
*/
|
|
void __init time_init(void)
|
|
{
|
|
tsc_init();
|
|
late_time_init = choose_time_init();
|
|
}
|