/*
   * linux/kernel/time/clockevents.c
   *
   * This file contains functions which manage clock event devices.
   *
   * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
   * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
   * Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
   *
   * This code is licenced under the GPL version 2. For details see
   * kernel-base/COPYING.
   */
  
  #include <linux/clockchips.h>
  #include <linux/hrtimer.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/notifier.h>
  #include <linux/smp.h>
  #include <linux/sysdev.h>

  #include <linux/tick.h>

  #include "tick-internal.h"

  /* The registered clock event devices */
  static LIST_HEAD(clockevent_devices);
  static LIST_HEAD(clockevents_released);
  
  /* Notification for clock events */
  static RAW_NOTIFIER_HEAD(clockevents_chain);
  
  /* Protection for the above */

  static DEFINE_RAW_SPINLOCK(clockevents_lock);

  
  /**
   * clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds
   * @latch:	value to convert
   * @evt:	pointer to clock event device descriptor
   *
   * Math helper, returns latch value converted to nanoseconds (bound checked)
   */

  u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)

  {

  	u64 clc = (u64) latch << evt->shift;

  	if (unlikely(!evt->mult)) {
  		evt->mult = 1;
  		WARN_ON(1);
  	}

  	do_div(clc, evt->mult);
  	if (clc < 1000)
  		clc = 1000;

  	if (clc > KTIME_MAX)
  		clc = KTIME_MAX;

  	return clc;

  }

  EXPORT_SYMBOL_GPL(clockevent_delta2ns);

  
  /**
   * clockevents_set_mode - set the operating mode of a clock event device
   * @dev:	device to modify
   * @mode:	new mode
   *
   * Must be called with interrupts disabled !
   */
  void clockevents_set_mode(struct clock_event_device *dev,
  				 enum clock_event_mode mode)
  {
  	if (dev->mode != mode) {
  		dev->set_mode(mode, dev);
  		dev->mode = mode;

  
  		/*
  		 * A nsec2cyc multiplicator of 0 is invalid and we'd crash
  		 * on it, so fix it up and emit a warning:
  		 */
  		if (mode == CLOCK_EVT_MODE_ONESHOT) {
  			if (unlikely(!dev->mult)) {
  				dev->mult = 1;
  				WARN_ON(1);
  			}
  		}

  	}
  }
  
  /**

   * clockevents_shutdown - shutdown the device and clear next_event
   * @dev:	device to shutdown
   */
  void clockevents_shutdown(struct clock_event_device *dev)
  {
  	clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
  	dev->next_event.tv64 = KTIME_MAX;
  }
  
  /**

   * clockevents_program_event - Reprogram the clock event device.
   * @expires:	absolute expiry time (monotonic clock)
   *
   * Returns 0 on success, -ETIME when the event is in the past.
   */
  int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
  			      ktime_t now)
  {
  	unsigned long long clc;
  	int64_t delta;

  	if (unlikely(expires.tv64 < 0)) {
  		WARN_ON_ONCE(1);
  		return -ETIME;
  	}

  	delta = ktime_to_ns(ktime_sub(expires, now));
  
  	if (delta <= 0)
  		return -ETIME;
  
  	dev->next_event = expires;
  
  	if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
  		return 0;
  
  	if (delta > dev->max_delta_ns)
  		delta = dev->max_delta_ns;
  	if (delta < dev->min_delta_ns)
  		delta = dev->min_delta_ns;
  
  	clc = delta * dev->mult;
  	clc >>= dev->shift;
  
  	return dev->set_next_event((unsigned long) clc, dev);
  }
  
  /**
   * clockevents_register_notifier - register a clock events change listener
   */
  int clockevents_register_notifier(struct notifier_block *nb)
  {

  	unsigned long flags;

  	int ret;

  	raw_spin_lock_irqsave(&clockevents_lock, flags);

  	ret = raw_notifier_chain_register(&clockevents_chain, nb);

  	raw_spin_unlock_irqrestore(&clockevents_lock, flags);

  
  	return ret;
  }

  /*
   * Notify about a clock event change. Called with clockevents_lock
   * held.
   */
  static void clockevents_do_notify(unsigned long reason, void *dev)
  {
  	raw_notifier_call_chain(&clockevents_chain, reason, dev);
  }
  
  /*

   * Called after a notify add to make devices available which were

   * released from the notifier call.
   */
  static void clockevents_notify_released(void)
  {
  	struct clock_event_device *dev;
  
  	while (!list_empty(&clockevents_released)) {
  		dev = list_entry(clockevents_released.next,
  				 struct clock_event_device, list);
  		list_del(&dev->list);
  		list_add(&dev->list, &clockevent_devices);
  		clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
  	}
  }
  
  /**
   * clockevents_register_device - register a clock event device
   * @dev:	device to register
   */
  void clockevents_register_device(struct clock_event_device *dev)
  {

  	unsigned long flags;

  	BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);

  	BUG_ON(!dev->cpumask);

  	raw_spin_lock_irqsave(&clockevents_lock, flags);

  
  	list_add(&dev->list, &clockevent_devices);
  	clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
  	clockevents_notify_released();

  	raw_spin_unlock_irqrestore(&clockevents_lock, flags);

  }

  EXPORT_SYMBOL_GPL(clockevents_register_device);

  
  /*
   * Noop handler when we shut down an event device
   */

  void clockevents_handle_noop(struct clock_event_device *dev)

  {
  }
  
  /**
   * clockevents_exchange_device - release and request clock devices
   * @old:	device to release (can be NULL)
   * @new:	device to request (can be NULL)
   *
   * Called from the notifier chain. clockevents_lock is held already
   */
  void clockevents_exchange_device(struct clock_event_device *old,
  				 struct clock_event_device *new)
  {
  	unsigned long flags;
  
  	local_irq_save(flags);
  	/*
  	 * Caller releases a clock event device. We queue it into the
  	 * released list and do a notify add later.
  	 */
  	if (old) {

  		clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
  		list_del(&old->list);
  		list_add(&old->list, &clockevents_released);
  	}
  
  	if (new) {
  		BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED);

  		clockevents_shutdown(new);

  	}
  	local_irq_restore(flags);
  }

  #ifdef CONFIG_GENERIC_CLOCKEVENTS

  /**

   * clockevents_notify - notification about relevant events
   */
  void clockevents_notify(unsigned long reason, void *arg)
  {

  	struct clock_event_device *dev, *tmp;

  	unsigned long flags;

  	int cpu;

  	raw_spin_lock_irqsave(&clockevents_lock, flags);

  	clockevents_do_notify(reason, arg);
  
  	switch (reason) {
  	case CLOCK_EVT_NOTIFY_CPU_DEAD:
  		/*
  		 * Unregister the clock event devices which were
  		 * released from the users in the notify chain.
  		 */

  		list_for_each_entry_safe(dev, tmp, &clockevents_released, list)
  			list_del(&dev->list);
  		/*
  		 * Now check whether the CPU has left unused per cpu devices
  		 */
  		cpu = *((int *)arg);
  		list_for_each_entry_safe(dev, tmp, &clockevent_devices, list) {
  			if (cpumask_test_cpu(cpu, dev->cpumask) &&

  			    cpumask_weight(dev->cpumask) == 1 &&
  			    !tick_is_broadcast_device(dev)) {

  				BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
  				list_del(&dev->list);
  			}
  		}

  		break;
  	default:
  		break;
  	}

  	raw_spin_unlock_irqrestore(&clockevents_lock, flags);

  }
  EXPORT_SYMBOL_GPL(clockevents_notify);

  #endif