/*
   * linux/kernel/time/tick-broadcast.c
   *
   * This file contains functions which emulate a local clock-event
   * device via a broadcast event source.
   *
   * 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/cpu.h>
  #include <linux/err.h>
  #include <linux/hrtimer.h>

  #include <linux/interrupt.h>

  #include <linux/percpu.h>
  #include <linux/profile.h>
  #include <linux/sched.h>

  
  #include "tick-internal.h"
  
  /*
   * Broadcast support for broken x86 hardware, where the local apic
   * timer stops in C3 state.
   */

  static struct tick_device tick_broadcast_device;

  /* FIXME: Use cpumask_var_t. */
  static DECLARE_BITMAP(tick_broadcast_mask, NR_CPUS);
  static DECLARE_BITMAP(tmpmask, NR_CPUS);

  static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);

  static int tick_broadcast_force;

  #ifdef CONFIG_TICK_ONESHOT
  static void tick_broadcast_clear_oneshot(int cpu);
  #else
  static inline void tick_broadcast_clear_oneshot(int cpu) { }
  #endif

  /*

   * Debugging: see timer_list.c
   */
  struct tick_device *tick_get_broadcast_device(void)
  {
  	return &tick_broadcast_device;
  }

  struct cpumask *tick_get_broadcast_mask(void)

  {

  	return to_cpumask(tick_broadcast_mask);

  }
  
  /*

   * Start the device in periodic mode
   */
  static void tick_broadcast_start_periodic(struct clock_event_device *bc)
  {

  	if (bc)

  		tick_setup_periodic(bc, 1);
  }
  
  /*
   * Check, if the device can be utilized as broadcast device:
   */
  int tick_check_broadcast_device(struct clock_event_device *dev)
  {

  	if ((tick_broadcast_device.evtdev &&
  	     tick_broadcast_device.evtdev->rating >= dev->rating) ||
  	     (dev->features & CLOCK_EVT_FEAT_C3STOP))

  		return 0;

  	clockevents_exchange_device(tick_broadcast_device.evtdev, dev);

  	tick_broadcast_device.evtdev = dev;

  	if (!cpumask_empty(tick_get_broadcast_mask()))

  		tick_broadcast_start_periodic(dev);
  	return 1;
  }
  
  /*
   * Check, if the device is the broadcast device
   */
  int tick_is_broadcast_device(struct clock_event_device *dev)
  {
  	return (dev && tick_broadcast_device.evtdev == dev);
  }
  
  /*
   * Check, if the device is disfunctional and a place holder, which
   * needs to be handled by the broadcast device.
   */
  int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
  {
  	unsigned long flags;
  	int ret = 0;

  	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

  
  	/*
  	 * Devices might be registered with both periodic and oneshot
  	 * mode disabled. This signals, that the device needs to be
  	 * operated from the broadcast device and is a placeholder for
  	 * the cpu local device.
  	 */
  	if (!tick_device_is_functional(dev)) {
  		dev->event_handler = tick_handle_periodic;

  		cpumask_set_cpu(cpu, tick_get_broadcast_mask());

  		tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
  		ret = 1;

  	} else {
  		/*
  		 * When the new device is not affected by the stop
  		 * feature and the cpu is marked in the broadcast mask
  		 * then clear the broadcast bit.
  		 */
  		if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
  			int cpu = smp_processor_id();

  			cpumask_clear_cpu(cpu, tick_get_broadcast_mask());

  			tick_broadcast_clear_oneshot(cpu);
  		}
  	}

  	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);

  	return ret;
  }
  
  /*

   * Broadcast the event to the cpus, which are set in the mask (mangled).

   */

  static void tick_do_broadcast(struct cpumask *mask)

  {

  	int cpu = smp_processor_id();

  	struct tick_device *td;
  
  	/*
  	 * Check, if the current cpu is in the mask
  	 */

  	if (cpumask_test_cpu(cpu, mask)) {
  		cpumask_clear_cpu(cpu, mask);

  		td = &per_cpu(tick_cpu_device, cpu);
  		td->evtdev->event_handler(td->evtdev);

  	}

  	if (!cpumask_empty(mask)) {

  		/*
  		 * It might be necessary to actually check whether the devices
  		 * have different broadcast functions. For now, just use the
  		 * one of the first device. This works as long as we have this
  		 * misfeature only on x86 (lapic)
  		 */

  		td = &per_cpu(tick_cpu_device, cpumask_first(mask));
  		td->evtdev->broadcast(mask);

  	}

  }
  
  /*
   * Periodic broadcast:
   * - invoke the broadcast handlers
   */
  static void tick_do_periodic_broadcast(void)
  {

  	raw_spin_lock(&tick_broadcast_lock);

  	cpumask_and(to_cpumask(tmpmask),
  		    cpu_online_mask, tick_get_broadcast_mask());
  	tick_do_broadcast(to_cpumask(tmpmask));

  	raw_spin_unlock(&tick_broadcast_lock);

  }
  
  /*
   * Event handler for periodic broadcast ticks
   */
  static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
  {

  	ktime_t next;

  	tick_do_periodic_broadcast();
  
  	/*
  	 * The device is in periodic mode. No reprogramming necessary:
  	 */
  	if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
  		return;
  
  	/*
  	 * Setup the next period for devices, which do not have

  	 * periodic mode. We read dev->next_event first and add to it

  	 * when the event already expired. clockevents_program_event()

  	 * sets dev->next_event only when the event is really
  	 * programmed to the device.

  	 */

  	for (next = dev->next_event; ;) {
  		next = ktime_add(next, tick_period);

  		if (!clockevents_program_event(dev, next, false))

  			return;
  		tick_do_periodic_broadcast();
  	}
  }
  
  /*
   * Powerstate information: The system enters/leaves a state, where
   * affected devices might stop
   */

  static void tick_do_broadcast_on_off(unsigned long *reason)

  {
  	struct clock_event_device *bc, *dev;
  	struct tick_device *td;

  	unsigned long flags;

  	int cpu, bc_stopped;

  	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

  
  	cpu = smp_processor_id();
  	td = &per_cpu(tick_cpu_device, cpu);
  	dev = td->evtdev;
  	bc = tick_broadcast_device.evtdev;
  
  	/*

  	 * Is the device not affected by the powerstate ?

  	 */

  	if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))

  		goto out;

  	if (!tick_device_is_functional(dev))
  		goto out;

  	bc_stopped = cpumask_empty(tick_get_broadcast_mask());

  	switch (*reason) {
  	case CLOCK_EVT_NOTIFY_BROADCAST_ON:
  	case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:

  		if (!cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
  			cpumask_set_cpu(cpu, tick_get_broadcast_mask());

  			if (tick_broadcast_device.mode ==
  			    TICKDEV_MODE_PERIODIC)

  				clockevents_shutdown(dev);

  		}

  		if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE)

  			tick_broadcast_force = 1;

  		break;
  	case CLOCK_EVT_NOTIFY_BROADCAST_OFF:

  		if (!tick_broadcast_force &&

  		    cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
  			cpumask_clear_cpu(cpu, tick_get_broadcast_mask());

  			if (tick_broadcast_device.mode ==
  			    TICKDEV_MODE_PERIODIC)

  				tick_setup_periodic(dev, 0);
  		}

  		break;

  	}

  	if (cpumask_empty(tick_get_broadcast_mask())) {

  		if (!bc_stopped)

  			clockevents_shutdown(bc);

  	} else if (bc_stopped) {

  		if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
  			tick_broadcast_start_periodic(bc);

  		else
  			tick_broadcast_setup_oneshot(bc);

  	}
  out:

  	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);

  }
  
  /*
   * Powerstate information: The system enters/leaves a state, where
   * affected devices might stop.
   */
  void tick_broadcast_on_off(unsigned long reason, int *oncpu)
  {

  	if (!cpumask_test_cpu(*oncpu, cpu_online_mask))

  		printk(KERN_ERR "tick-broadcast: ignoring broadcast for "

  		       "offline CPU #%d
  ", *oncpu);

  	else

  		tick_do_broadcast_on_off(&reason);

  }
  
  /*
   * Set the periodic handler depending on broadcast on/off
   */
  void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
  {
  	if (!broadcast)
  		dev->event_handler = tick_handle_periodic;
  	else
  		dev->event_handler = tick_handle_periodic_broadcast;
  }
  
  /*
   * Remove a CPU from broadcasting
   */
  void tick_shutdown_broadcast(unsigned int *cpup)
  {
  	struct clock_event_device *bc;
  	unsigned long flags;
  	unsigned int cpu = *cpup;

  	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

  
  	bc = tick_broadcast_device.evtdev;

  	cpumask_clear_cpu(cpu, tick_get_broadcast_mask());

  
  	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {

  		if (bc && cpumask_empty(tick_get_broadcast_mask()))

  			clockevents_shutdown(bc);

  	}

  	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);

  }

  void tick_suspend_broadcast(void)
  {
  	struct clock_event_device *bc;
  	unsigned long flags;

  	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

  
  	bc = tick_broadcast_device.evtdev;

  	if (bc)

  		clockevents_shutdown(bc);

  	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);

  }
  
  int tick_resume_broadcast(void)
  {
  	struct clock_event_device *bc;
  	unsigned long flags;
  	int broadcast = 0;

  	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

  
  	bc = tick_broadcast_device.evtdev;

  	if (bc) {

  		clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);

  		switch (tick_broadcast_device.mode) {
  		case TICKDEV_MODE_PERIODIC:

  			if (!cpumask_empty(tick_get_broadcast_mask()))

  				tick_broadcast_start_periodic(bc);

  			broadcast = cpumask_test_cpu(smp_processor_id(),
  						     tick_get_broadcast_mask());

  			break;
  		case TICKDEV_MODE_ONESHOT:
  			broadcast = tick_resume_broadcast_oneshot(bc);
  			break;
  		}

  	}

  	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);

  
  	return broadcast;
  }

  #ifdef CONFIG_TICK_ONESHOT

  /* FIXME: use cpumask_var_t. */
  static DECLARE_BITMAP(tick_broadcast_oneshot_mask, NR_CPUS);

  /*

   * Exposed for debugging: see timer_list.c

   */

  struct cpumask *tick_get_broadcast_oneshot_mask(void)

  {

  	return to_cpumask(tick_broadcast_oneshot_mask);

  }

  static int tick_broadcast_set_event(ktime_t expires, int force)
  {
  	struct clock_event_device *bc = tick_broadcast_device.evtdev;

  	return clockevents_program_event(bc, expires, force);

  }

  int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
  {
  	clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);

  	return 0;

  }

  /*

   * Called from irq_enter() when idle was interrupted to reenable the
   * per cpu device.
   */
  void tick_check_oneshot_broadcast(int cpu)
  {

  	if (cpumask_test_cpu(cpu, to_cpumask(tick_broadcast_oneshot_mask))) {

  		struct tick_device *td = &per_cpu(tick_cpu_device, cpu);
  
  		clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_ONESHOT);
  	}
  }
  
  /*

   * Handle oneshot mode broadcasting
   */
  static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
  {
  	struct tick_device *td;

  	ktime_t now, next_event;

  	int cpu;

  	raw_spin_lock(&tick_broadcast_lock);

  again:
  	dev->next_event.tv64 = KTIME_MAX;

  	next_event.tv64 = KTIME_MAX;

  	cpumask_clear(to_cpumask(tmpmask));

  	now = ktime_get();
  	/* Find all expired events */

  	for_each_cpu(cpu, tick_get_broadcast_oneshot_mask()) {

  		td = &per_cpu(tick_cpu_device, cpu);
  		if (td->evtdev->next_event.tv64 <= now.tv64)

  			cpumask_set_cpu(cpu, to_cpumask(tmpmask));

  		else if (td->evtdev->next_event.tv64 < next_event.tv64)
  			next_event.tv64 = td->evtdev->next_event.tv64;

  	}
  
  	/*

  	 * Wakeup the cpus which have an expired event.
  	 */

  	tick_do_broadcast(to_cpumask(tmpmask));

  
  	/*
  	 * Two reasons for reprogram:
  	 *
  	 * - The global event did not expire any CPU local
  	 * events. This happens in dyntick mode, as the maximum PIT
  	 * delta is quite small.
  	 *
  	 * - There are pending events on sleeping CPUs which were not
  	 * in the event mask

  	 */

  	if (next_event.tv64 != KTIME_MAX) {

  		/*

  		 * Rearm the broadcast device. If event expired,
  		 * repeat the above

  		 */

  		if (tick_broadcast_set_event(next_event, 0))

  			goto again;
  	}

  	raw_spin_unlock(&tick_broadcast_lock);

  }
  
  /*
   * Powerstate information: The system enters/leaves a state, where
   * affected devices might stop
   */
  void tick_broadcast_oneshot_control(unsigned long reason)
  {
  	struct clock_event_device *bc, *dev;
  	struct tick_device *td;
  	unsigned long flags;
  	int cpu;

  	/*
  	 * Periodic mode does not care about the enter/exit of power
  	 * states
  	 */
  	if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)

  		return;

  	/*
  	 * We are called with preemtion disabled from the depth of the
  	 * idle code, so we can't be moved away.
  	 */

  	cpu = smp_processor_id();
  	td = &per_cpu(tick_cpu_device, cpu);
  	dev = td->evtdev;
  
  	if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))

  		return;
  
  	bc = tick_broadcast_device.evtdev;

  	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

  	if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {

  		if (!cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
  			cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask());

  			clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
  			if (dev->next_event.tv64 < bc->next_event.tv64)
  				tick_broadcast_set_event(dev->next_event, 1);
  		}
  	} else {

  		if (cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
  			cpumask_clear_cpu(cpu,
  					  tick_get_broadcast_oneshot_mask());

  			clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
  			if (dev->next_event.tv64 != KTIME_MAX)
  				tick_program_event(dev->next_event, 1);
  		}
  	}

  	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);

  }

  /*
   * Reset the one shot broadcast for a cpu
   *
   * Called with tick_broadcast_lock held
   */
  static void tick_broadcast_clear_oneshot(int cpu)
  {

  	cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());

  }

  static void tick_broadcast_init_next_event(struct cpumask *mask,
  					   ktime_t expires)

  {
  	struct tick_device *td;
  	int cpu;

  	for_each_cpu(cpu, mask) {

  		td = &per_cpu(tick_cpu_device, cpu);
  		if (td->evtdev)
  			td->evtdev->next_event = expires;
  	}
  }

  /**

   * tick_broadcast_setup_oneshot - setup the broadcast device

   */
  void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
  {

  	int cpu = smp_processor_id();

  	/* Set it up only once ! */
  	if (bc->event_handler != tick_handle_oneshot_broadcast) {

  		int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;

  		bc->event_handler = tick_handle_oneshot_broadcast;
  		clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);

  
  		/* Take the do_timer update */
  		tick_do_timer_cpu = cpu;
  
  		/*
  		 * We must be careful here. There might be other CPUs
  		 * waiting for periodic broadcast. We need to set the
  		 * oneshot_mask bits for those and program the
  		 * broadcast device to fire.
  		 */

  		cpumask_copy(to_cpumask(tmpmask), tick_get_broadcast_mask());
  		cpumask_clear_cpu(cpu, to_cpumask(tmpmask));
  		cpumask_or(tick_get_broadcast_oneshot_mask(),
  			   tick_get_broadcast_oneshot_mask(),
  			   to_cpumask(tmpmask));
  
  		if (was_periodic && !cpumask_empty(to_cpumask(tmpmask))) {
  			tick_broadcast_init_next_event(to_cpumask(tmpmask),
  						       tick_next_period);

  			tick_broadcast_set_event(tick_next_period, 1);
  		} else
  			bc->next_event.tv64 = KTIME_MAX;

  	} else {
  		/*
  		 * The first cpu which switches to oneshot mode sets
  		 * the bit for all other cpus which are in the general
  		 * (periodic) broadcast mask. So the bit is set and
  		 * would prevent the first broadcast enter after this
  		 * to program the bc device.
  		 */
  		tick_broadcast_clear_oneshot(cpu);

  	}

  }
  
  /*
   * Select oneshot operating mode for the broadcast device
   */
  void tick_broadcast_switch_to_oneshot(void)
  {
  	struct clock_event_device *bc;
  	unsigned long flags;

  	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

  
  	tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT;
  	bc = tick_broadcast_device.evtdev;
  	if (bc)
  		tick_broadcast_setup_oneshot(bc);

  	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);

  }
  
  
  /*
   * Remove a dead CPU from broadcasting
   */
  void tick_shutdown_broadcast_oneshot(unsigned int *cpup)
  {

  	unsigned long flags;
  	unsigned int cpu = *cpup;

  	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);

  	/*
  	 * Clear the broadcast mask flag for the dead cpu, but do not
  	 * stop the broadcast device!
  	 */

  	cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());

  	raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);

  }

  /*
   * Check, whether the broadcast device is in one shot mode
   */
  int tick_broadcast_oneshot_active(void)
  {
  	return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
  }

  /*
   * Check whether the broadcast device supports oneshot.
   */
  bool tick_broadcast_oneshot_available(void)
  {
  	struct clock_event_device *bc = tick_broadcast_device.evtdev;
  
  	return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
  }

  #endif