text: /*
   * 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 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;
  }
  