time.c

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/*
 *  Copyright (c) 1991,1992,1995  Linus Torvalds
 *  Copyright (c) 1994  Alan Modra
 *  Copyright (c) 1995  Markus Kuhn
 *  Copyright (c) 1996  Ingo Molnar
 *  Copyright (c) 1998  Andrea Arcangeli
 *  Copyright (c) 2002,2006  Vojtech Pavlik
 *  Copyright (c) 2003  Andi Kleen
 *
 */

#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/i8253.h>
#include <linux/time.h>
#include <linux/export.h>

#include <asm/vsyscall.h>
#include <asm/x86_init.h>
#include <asm/i8259.h>
#include <asm/timer.h>
#include <asm/hpet.h>
#include <asm/time.h>

#ifdef CONFIG_X86_64
DEFINE_VVAR(volatile unsigned long, jiffies) = INITIAL_JIFFIES;
#endif

unsigned long profile_pc(struct pt_regs *regs)
{
    unsigned long pc = instruction_pointer(regs);

    if (!user_mode_vm(regs) && in_lock_functions(pc)) {
#ifdef CONFIG_FRAME_POINTER
        return *(unsigned long *)(regs->bp + sizeof(long));
#else
        unsigned long *sp =
            (unsigned long *)kernel_stack_pointer(regs);
        /*
         * 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
    }
    return pc;
}
EXPORT_SYMBOL(profile_pc);

/*
 * Default timer interrupt handler for PIT/HPET
 */
static irqreturn_t timer_interrupt(int irq, void *dev_id)
{
    global_clock_event->event_handler(global_clock_event);
    return IRQ_HANDLED;
}

static struct irqaction irq0  = {
    .handler = timer_interrupt,
    .flags = IRQF_DISABLED | IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER,
    .name = "timer"
};

void __init setup_default_timer_irq(void)
{
    setup_irq(0, &irq0);
}

/* Default timer init function */
void __init hpet_time_init(void)
{
    if (!hpet_enable())
        setup_pit_timer();
    setup_default_timer_irq();
}

static __init void x86_late_time_init(void)
{
    x86_init.timers.timer_init();
    tsc_init();
}

/*
 * Initialize TSC and delay the periodic timer init to
 * late x86_late_time_init() so ioremap works.
 */
void __init time_init(void)
{
    late_time_init = x86_late_time_init;
}