time.c

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/*
 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <linux/clockchips.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/threads.h>
#include <asm/irq.h>
#include <asm/param.h>
#include <kern_util.h>
#include <os.h>

void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
{
    unsigned long flags;

    local_irq_save(flags);
    do_IRQ(TIMER_IRQ, regs);
    local_irq_restore(flags);
}

static void itimer_set_mode(enum clock_event_mode mode,
                struct clock_event_device *evt)
{
    switch (mode) {
    case CLOCK_EVT_MODE_PERIODIC:
        set_interval();
        break;

    case CLOCK_EVT_MODE_SHUTDOWN:
    case CLOCK_EVT_MODE_UNUSED:
    case CLOCK_EVT_MODE_ONESHOT:
        disable_timer();
        break;

    case CLOCK_EVT_MODE_RESUME:
        break;
    }
}

static int itimer_next_event(unsigned long delta,
                 struct clock_event_device *evt)
{
    return timer_one_shot(delta + 1);
}

static struct clock_event_device itimer_clockevent = {
    .name       = "itimer",
    .rating     = 250,
    .cpumask    = cpu_all_mask,
    .features   = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
    .set_mode   = itimer_set_mode,
    .set_next_event = itimer_next_event,
    .shift      = 32,
    .irq        = 0,
};

static irqreturn_t um_timer(int irq, void *dev)
{
    (*itimer_clockevent.event_handler)(&itimer_clockevent);

    return IRQ_HANDLED;
}

static cycle_t itimer_read(struct clocksource *cs)
{
    return os_nsecs() / 1000;
}

static struct clocksource itimer_clocksource = {
    .name       = "itimer",
    .rating     = 300,
    .read       = itimer_read,
    .mask       = CLOCKSOURCE_MASK(64),
    .flags      = CLOCK_SOURCE_IS_CONTINUOUS,
};

static void __init setup_itimer(void)
{
    int err;

    err = request_irq(TIMER_IRQ, um_timer, 0, "timer", NULL);
    if (err != 0)
        printk(KERN_ERR "register_timer : request_irq failed - "
               "errno = %d\n", -err);

    itimer_clockevent.mult = div_sc(HZ, NSEC_PER_SEC, 32);
    itimer_clockevent.max_delta_ns =
        clockevent_delta2ns(60 * HZ, &itimer_clockevent);
    itimer_clockevent.min_delta_ns =
        clockevent_delta2ns(1, &itimer_clockevent);
    err = clocksource_register_hz(&itimer_clocksource, USEC_PER_SEC);
    if (err) {
        printk(KERN_ERR "clocksource_register_hz returned %d\n", err);
        return;
    }
    clockevents_register_device(&itimer_clockevent);
}

void read_persistent_clock(struct timespec *ts)
{
    long long nsecs = os_nsecs();

    set_normalized_timespec(ts, nsecs / NSEC_PER_SEC,
                nsecs % NSEC_PER_SEC);
}

void __init time_init(void)
{
    timer_init();
    late_time_init = setup_itimer;
}