--- /dev/null
+/*
+ * 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 <linux/smp.h>
+#include <linux/module.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;
+static cpumask_var_t tick_broadcast_mask;
+static cpumask_var_t tick_broadcast_on;
+static cpumask_var_t tmpmask;
+static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
+static int tick_broadcast_forced;
+
+#ifdef CONFIG_TICK_ONESHOT
+static void tick_broadcast_clear_oneshot(int cpu);
+static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
+#else
+static inline void tick_broadcast_clear_oneshot(int cpu) { }
+static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
+#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 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:
+ */
+static bool tick_check_broadcast_device(struct clock_event_device *curdev,
+ struct clock_event_device *newdev)
+{
+ if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
+ (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
+ (newdev->features & CLOCK_EVT_FEAT_C3STOP))
+ return false;
+
+ if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
+ !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
+ return false;
+
+ return !curdev || newdev->rating > curdev->rating;
+}
+
+/*
+ * Conditionally install/replace broadcast device
+ */
+void tick_install_broadcast_device(struct clock_event_device *dev)
+{
+ struct clock_event_device *cur = tick_broadcast_device.evtdev;
+
+ if (!tick_check_broadcast_device(cur, dev))
+ return;
+
+ if (!try_module_get(dev->owner))
+ return;
+
+ clockevents_exchange_device(cur, dev);
+ if (cur)
+ cur->event_handler = clockevents_handle_noop;
+ tick_broadcast_device.evtdev = dev;
+ if (!cpumask_empty(tick_broadcast_mask))
+ tick_broadcast_start_periodic(dev);
+ /*
+ * Inform all cpus about this. We might be in a situation
+ * where we did not switch to oneshot mode because the per cpu
+ * devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack
+ * of a oneshot capable broadcast device. Without that
+ * notification the systems stays stuck in periodic mode
+ * forever.
+ */
+ if (dev->features & CLOCK_EVT_FEAT_ONESHOT)
+ tick_clock_notify();
+}
+
+/*
+ * 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);
+}
+
+int tick_broadcast_update_freq(struct clock_event_device *dev, u32 freq)
+{
+ int ret = -ENODEV;
+
+ if (tick_is_broadcast_device(dev)) {
+ raw_spin_lock(&tick_broadcast_lock);
+ ret = __clockevents_update_freq(dev, freq);
+ raw_spin_unlock(&tick_broadcast_lock);
+ }
+ return ret;
+}
+
+
+static void err_broadcast(const struct cpumask *mask)
+{
+ pr_crit_once("Failed to broadcast timer tick. Some CPUs may be unresponsive.\n");
+}
+
+static void tick_device_setup_broadcast_func(struct clock_event_device *dev)
+{
+ if (!dev->broadcast)
+ dev->broadcast = tick_broadcast;
+ if (!dev->broadcast) {
+ pr_warn_once("%s depends on broadcast, but no broadcast function available\n",
+ dev->name);
+ dev->broadcast = err_broadcast;
+ }
+}
+
+/*
+ * 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)
+{
+ struct clock_event_device *bc = tick_broadcast_device.evtdev;
+ unsigned long flags;
+ int ret;
+
+ 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;
+ tick_device_setup_broadcast_func(dev);
+ cpumask_set_cpu(cpu, tick_broadcast_mask);
+ if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+ tick_broadcast_start_periodic(bc);
+ else
+ tick_broadcast_setup_oneshot(bc);
+ ret = 1;
+ } else {
+ /*
+ * Clear the broadcast bit for this cpu if the
+ * device is not power state affected.
+ */
+ if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
+ cpumask_clear_cpu(cpu, tick_broadcast_mask);
+ else
+ tick_device_setup_broadcast_func(dev);
+
+ /*
+ * Clear the broadcast bit if the CPU is not in
+ * periodic broadcast on state.
+ */
+ if (!cpumask_test_cpu(cpu, tick_broadcast_on))
+ cpumask_clear_cpu(cpu, tick_broadcast_mask);
+
+ switch (tick_broadcast_device.mode) {
+ case TICKDEV_MODE_ONESHOT:
+ /*
+ * If the system is in oneshot mode we can
+ * unconditionally clear the oneshot mask bit,
+ * because the CPU is running and therefore
+ * not in an idle state which causes the power
+ * state affected device to stop. Let the
+ * caller initialize the device.
+ */
+ tick_broadcast_clear_oneshot(cpu);
+ ret = 0;
+ break;
+
+ case TICKDEV_MODE_PERIODIC:
+ /*
+ * If the system is in periodic mode, check
+ * whether the broadcast device can be
+ * switched off now.
+ */
+ if (cpumask_empty(tick_broadcast_mask) && bc)
+ clockevents_shutdown(bc);
+ /*
+ * If we kept the cpu in the broadcast mask,
+ * tell the caller to leave the per cpu device
+ * in shutdown state. The periodic interrupt
+ * is delivered by the broadcast device.
+ */
+ ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
+ break;
+ default:
+ /* Nothing to do */
+ ret = 0;
+ break;
+ }
+ }
+ raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+ return ret;
+}
+
+#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
+int tick_receive_broadcast(void)
+{
+ struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
+ struct clock_event_device *evt = td->evtdev;
+
+ if (!evt)
+ return -ENODEV;
+
+ if (!evt->event_handler)
+ return -EINVAL;
+
+ evt->event_handler(evt);
+ return 0;
+}
+#endif
+
+/*
+ * 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)
+{
+ cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
+ tick_do_broadcast(tmpmask);
+}
+
+/*
+ * Event handler for periodic broadcast ticks
+ */
+static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
+{
+ ktime_t next;
+
+ raw_spin_lock(&tick_broadcast_lock);
+
+ tick_do_periodic_broadcast();
+
+ /*
+ * The device is in periodic mode. No reprogramming necessary:
+ */
+ if (dev->state == CLOCK_EVT_STATE_PERIODIC)
+ goto unlock;
+
+ /*
+ * 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))
+ goto unlock;
+ tick_do_periodic_broadcast();
+ }
+unlock:
+ raw_spin_unlock(&tick_broadcast_lock);
+}
+
+/**
+ * tick_broadcast_control - Enable/disable or force broadcast mode
+ * @mode: The selected broadcast mode
+ *
+ * Called when the system enters a state where affected tick devices
+ * might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
+ *
+ * Called with interrupts disabled, so clockevents_lock is not
+ * required here because the local clock event device cannot go away
+ * under us.
+ */
+void tick_broadcast_control(enum tick_broadcast_mode mode)
+{
+ struct clock_event_device *bc, *dev;
+ struct tick_device *td;
+ int cpu, bc_stopped;
+
+ td = this_cpu_ptr(&tick_cpu_device);
+ dev = td->evtdev;
+
+ /*
+ * Is the device not affected by the powerstate ?
+ */
+ if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
+ return;
+
+ if (!tick_device_is_functional(dev))
+ return;
+
+ raw_spin_lock(&tick_broadcast_lock);
+ cpu = smp_processor_id();
+ bc = tick_broadcast_device.evtdev;
+ bc_stopped = cpumask_empty(tick_broadcast_mask);
+
+ switch (mode) {
+ case TICK_BROADCAST_FORCE:
+ tick_broadcast_forced = 1;
+ case TICK_BROADCAST_ON:
+ cpumask_set_cpu(cpu, tick_broadcast_on);
+ if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
+ if (tick_broadcast_device.mode ==
+ TICKDEV_MODE_PERIODIC)
+ clockevents_shutdown(dev);
+ }
+ break;
+
+ case TICK_BROADCAST_OFF:
+ if (tick_broadcast_forced)
+ break;
+ cpumask_clear_cpu(cpu, tick_broadcast_on);
+ if (!tick_device_is_functional(dev))
+ break;
+ if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
+ if (tick_broadcast_device.mode ==
+ TICKDEV_MODE_PERIODIC)
+ tick_setup_periodic(dev, 0);
+ }
+ break;
+ }
+
+ if (cpumask_empty(tick_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);
+ }
+ raw_spin_unlock(&tick_broadcast_lock);
+}
+EXPORT_SYMBOL_GPL(tick_broadcast_control);
+
+/*
+ * 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;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * Remove a CPU from broadcasting
+ */
+void tick_shutdown_broadcast(unsigned int cpu)
+{
+ struct clock_event_device *bc;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+ bc = tick_broadcast_device.evtdev;
+ cpumask_clear_cpu(cpu, tick_broadcast_mask);
+ cpumask_clear_cpu(cpu, tick_broadcast_on);
+
+ if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
+ if (bc && cpumask_empty(tick_broadcast_mask))
+ clockevents_shutdown(bc);
+ }
+
+ raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+#endif
+
+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);
+}
+
+/*
+ * This is called from tick_resume_local() on a resuming CPU. That's
+ * called from the core resume function, tick_unfreeze() and the magic XEN
+ * resume hackery.
+ *
+ * In none of these cases the broadcast device mode can change and the
+ * bit of the resuming CPU in the broadcast mask is safe as well.
+ */
+bool tick_resume_check_broadcast(void)
+{
+ if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT)
+ return false;
+ else
+ return cpumask_test_cpu(smp_processor_id(), tick_broadcast_mask);
+}
+
+void tick_resume_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_tick_resume(bc);
+
+ switch (tick_broadcast_device.mode) {
+ case TICKDEV_MODE_PERIODIC:
+ if (!cpumask_empty(tick_broadcast_mask))
+ tick_broadcast_start_periodic(bc);
+ break;
+ case TICKDEV_MODE_ONESHOT:
+ if (!cpumask_empty(tick_broadcast_mask))
+ tick_resume_broadcast_oneshot(bc);
+ break;
+ }
+ }
+ raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+#ifdef CONFIG_TICK_ONESHOT
+
+static cpumask_var_t tick_broadcast_oneshot_mask;
+static cpumask_var_t tick_broadcast_pending_mask;
+static cpumask_var_t tick_broadcast_force_mask;
+
+/*
+ * Exposed for debugging: see timer_list.c
+ */
+struct cpumask *tick_get_broadcast_oneshot_mask(void)
+{
+ return tick_broadcast_oneshot_mask;
+}
+
+/*
+ * Called before going idle with interrupts disabled. Checks whether a
+ * broadcast event from the other core is about to happen. We detected
+ * that in tick_broadcast_oneshot_control(). The callsite can use this
+ * to avoid a deep idle transition as we are about to get the
+ * broadcast IPI right away.
+ */
+int tick_check_broadcast_expired(void)
+{
+ return cpumask_test_cpu(smp_processor_id(), tick_broadcast_force_mask);
+}
+
+/*
+ * Set broadcast interrupt affinity
+ */
+static void tick_broadcast_set_affinity(struct clock_event_device *bc,
+ const struct cpumask *cpumask)
+{
+ if (!(bc->features & CLOCK_EVT_FEAT_DYNIRQ))
+ return;
+
+ if (cpumask_equal(bc->cpumask, cpumask))
+ return;
+
+ bc->cpumask = cpumask;
+ irq_set_affinity(bc->irq, bc->cpumask);
+}
+
+static int tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
+ ktime_t expires, int force)
+{
+ int ret;
+
+ if (bc->state != CLOCK_EVT_STATE_ONESHOT)
+ clockevents_set_state(bc, CLOCK_EVT_STATE_ONESHOT);
+
+ ret = clockevents_program_event(bc, expires, force);
+ if (!ret)
+ tick_broadcast_set_affinity(bc, cpumask_of(cpu));
+ return ret;
+}
+
+static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
+{
+ clockevents_set_state(bc, CLOCK_EVT_STATE_ONESHOT);
+}
+
+/*
+ * Called from irq_enter() when idle was interrupted to reenable the
+ * per cpu device.
+ */
+void tick_check_oneshot_broadcast_this_cpu(void)
+{
+ if (cpumask_test_cpu(smp_processor_id(), tick_broadcast_oneshot_mask)) {
+ struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
+
+ /*
+ * We might be in the middle of switching over from
+ * periodic to oneshot. If the CPU has not yet
+ * switched over, leave the device alone.
+ */
+ if (td->mode == TICKDEV_MODE_ONESHOT) {
+ clockevents_set_state(td->evtdev,
+ CLOCK_EVT_STATE_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, next_cpu = 0;
+
+ raw_spin_lock(&tick_broadcast_lock);
+again:
+ dev->next_event.tv64 = KTIME_MAX;
+ next_event.tv64 = KTIME_MAX;
+ cpumask_clear(tmpmask);
+ now = ktime_get();
+ /* Find all expired events */
+ for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
+ td = &per_cpu(tick_cpu_device, cpu);
+ if (td->evtdev->next_event.tv64 <= now.tv64) {
+ cpumask_set_cpu(cpu, tmpmask);
+ /*
+ * Mark the remote cpu in the pending mask, so
+ * it can avoid reprogramming the cpu local
+ * timer in tick_broadcast_oneshot_control().
+ */
+ cpumask_set_cpu(cpu, tick_broadcast_pending_mask);
+ } else if (td->evtdev->next_event.tv64 < next_event.tv64) {
+ next_event.tv64 = td->evtdev->next_event.tv64;
+ next_cpu = cpu;
+ }
+ }
+
+ /*
+ * Remove the current cpu from the pending mask. The event is
+ * delivered immediately in tick_do_broadcast() !
+ */
+ cpumask_clear_cpu(smp_processor_id(), tick_broadcast_pending_mask);
+
+ /* Take care of enforced broadcast requests */
+ cpumask_or(tmpmask, tmpmask, tick_broadcast_force_mask);
+ cpumask_clear(tick_broadcast_force_mask);
+
+ /*
+ * Sanity check. Catch the case where we try to broadcast to
+ * offline cpus.
+ */
+ if (WARN_ON_ONCE(!cpumask_subset(tmpmask, cpu_online_mask)))
+ cpumask_and(tmpmask, tmpmask, cpu_online_mask);
+
+ /*
+ * Wakeup the cpus which have an expired event.
+ */
+ tick_do_broadcast(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(dev, next_cpu, next_event, 0))
+ goto again;
+ }
+ raw_spin_unlock(&tick_broadcast_lock);
+}
+
+static int broadcast_needs_cpu(struct clock_event_device *bc, int cpu)
+{
+ if (!(bc->features & CLOCK_EVT_FEAT_HRTIMER))
+ return 0;
+ if (bc->next_event.tv64 == KTIME_MAX)
+ return 0;
+ return bc->bound_on == cpu ? -EBUSY : 0;
+}
+
+static void broadcast_shutdown_local(struct clock_event_device *bc,
+ struct clock_event_device *dev)
+{
+ /*
+ * For hrtimer based broadcasting we cannot shutdown the cpu
+ * local device if our own event is the first one to expire or
+ * if we own the broadcast timer.
+ */
+ if (bc->features & CLOCK_EVT_FEAT_HRTIMER) {
+ if (broadcast_needs_cpu(bc, smp_processor_id()))
+ return;
+ if (dev->next_event.tv64 < bc->next_event.tv64)
+ return;
+ }
+ clockevents_set_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
+}
+
+/**
+ * tick_broadcast_oneshot_control - Enter/exit broadcast oneshot mode
+ * @state: The target state (enter/exit)
+ *
+ * The system enters/leaves a state, where affected devices might stop
+ * Returns 0 on success, -EBUSY if the cpu is used to broadcast wakeups.
+ *
+ * Called with interrupts disabled, so clockevents_lock is not
+ * required here because the local clock event device cannot go away
+ * under us.
+ */
+int tick_broadcast_oneshot_control(enum tick_broadcast_state state)
+{
+ struct clock_event_device *bc, *dev;
+ struct tick_device *td;
+ int cpu, ret = 0;
+ ktime_t now;
+
+ /*
+ * Periodic mode does not care about the enter/exit of power
+ * states
+ */
+ if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+ return 0;
+
+ /*
+ * We are called with preemtion disabled from the depth of the
+ * idle code, so we can't be moved away.
+ */
+ td = this_cpu_ptr(&tick_cpu_device);
+ dev = td->evtdev;
+
+ if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
+ return 0;
+
+ raw_spin_lock(&tick_broadcast_lock);
+ bc = tick_broadcast_device.evtdev;
+ cpu = smp_processor_id();
+
+ if (state == TICK_BROADCAST_ENTER) {
+ if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
+ WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
+ broadcast_shutdown_local(bc, dev);
+ /*
+ * We only reprogram the broadcast timer if we
+ * did not mark ourself in the force mask and
+ * if the cpu local event is earlier than the
+ * broadcast event. If the current CPU is in
+ * the force mask, then we are going to be
+ * woken by the IPI right away.
+ */
+ if (!cpumask_test_cpu(cpu, tick_broadcast_force_mask) &&
+ dev->next_event.tv64 < bc->next_event.tv64)
+ tick_broadcast_set_event(bc, cpu, dev->next_event, 1);
+ }
+ /*
+ * If the current CPU owns the hrtimer broadcast
+ * mechanism, it cannot go deep idle and we remove the
+ * CPU from the broadcast mask. We don't have to go
+ * through the EXIT path as the local timer is not
+ * shutdown.
+ */
+ ret = broadcast_needs_cpu(bc, cpu);
+ if (ret)
+ cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
+ } else {
+ if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
+ clockevents_set_state(dev, CLOCK_EVT_STATE_ONESHOT);
+ /*
+ * The cpu which was handling the broadcast
+ * timer marked this cpu in the broadcast
+ * pending mask and fired the broadcast
+ * IPI. So we are going to handle the expired
+ * event anyway via the broadcast IPI
+ * handler. No need to reprogram the timer
+ * with an already expired event.
+ */
+ if (cpumask_test_and_clear_cpu(cpu,
+ tick_broadcast_pending_mask))
+ goto out;
+
+ /*
+ * Bail out if there is no next event.
+ */
+ if (dev->next_event.tv64 == KTIME_MAX)
+ goto out;
+ /*
+ * If the pending bit is not set, then we are
+ * either the CPU handling the broadcast
+ * interrupt or we got woken by something else.
+ *
+ * We are not longer in the broadcast mask, so
+ * if the cpu local expiry time is already
+ * reached, we would reprogram the cpu local
+ * timer with an already expired event.
+ *
+ * This can lead to a ping-pong when we return
+ * to idle and therefor rearm the broadcast
+ * timer before the cpu local timer was able
+ * to fire. This happens because the forced
+ * reprogramming makes sure that the event
+ * will happen in the future and depending on
+ * the min_delta setting this might be far
+ * enough out that the ping-pong starts.
+ *
+ * If the cpu local next_event has expired
+ * then we know that the broadcast timer
+ * next_event has expired as well and
+ * broadcast is about to be handled. So we
+ * avoid reprogramming and enforce that the
+ * broadcast handler, which did not run yet,
+ * will invoke the cpu local handler.
+ *
+ * We cannot call the handler directly from
+ * here, because we might be in a NOHZ phase
+ * and we did not go through the irq_enter()
+ * nohz fixups.
+ */
+ now = ktime_get();
+ if (dev->next_event.tv64 <= now.tv64) {
+ cpumask_set_cpu(cpu, tick_broadcast_force_mask);
+ goto out;
+ }
+ /*
+ * We got woken by something else. Reprogram
+ * the cpu local timer device.
+ */
+ tick_program_event(dev->next_event, 1);
+ }
+ }
+out:
+ raw_spin_unlock(&tick_broadcast_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(tick_broadcast_oneshot_control);
+
+/*
+ * 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_broadcast_oneshot_mask);
+ cpumask_clear_cpu(cpu, tick_broadcast_pending_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->state == CLOCK_EVT_STATE_PERIODIC;
+
+ bc->event_handler = tick_handle_oneshot_broadcast;
+
+ /*
+ * 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(tmpmask, tick_broadcast_mask);
+ cpumask_clear_cpu(cpu, tmpmask);
+ cpumask_or(tick_broadcast_oneshot_mask,
+ tick_broadcast_oneshot_mask, tmpmask);
+
+ if (was_periodic && !cpumask_empty(tmpmask)) {
+ clockevents_set_state(bc, CLOCK_EVT_STATE_ONESHOT);
+ tick_broadcast_init_next_event(tmpmask,
+ tick_next_period);
+ tick_broadcast_set_event(bc, cpu, 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);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+void hotplug_cpu__broadcast_tick_pull(int deadcpu)
+{
+ struct clock_event_device *bc;
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+ bc = tick_broadcast_device.evtdev;
+
+ if (bc && broadcast_needs_cpu(bc, deadcpu)) {
+ /* This moves the broadcast assignment to this CPU: */
+ clockevents_program_event(bc, bc->next_event, 1);
+ }
+ raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+
+/*
+ * Remove a dead CPU from broadcasting
+ */
+void tick_shutdown_broadcast_oneshot(unsigned int cpu)
+{
+ unsigned long flags;
+
+ raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
+
+ /*
+ * Clear the broadcast masks for the dead cpu, but do not stop
+ * the broadcast device!
+ */
+ cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
+ cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
+ cpumask_clear_cpu(cpu, tick_broadcast_force_mask);
+
+ raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
+}
+#endif
+
+/*
+ * 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
+
+void __init tick_broadcast_init(void)
+{
+ zalloc_cpumask_var(&tick_broadcast_mask, GFP_NOWAIT);
+ zalloc_cpumask_var(&tick_broadcast_on, GFP_NOWAIT);
+ zalloc_cpumask_var(&tmpmask, GFP_NOWAIT);
+#ifdef CONFIG_TICK_ONESHOT
+ zalloc_cpumask_var(&tick_broadcast_oneshot_mask, GFP_NOWAIT);
+ zalloc_cpumask_var(&tick_broadcast_pending_mask, GFP_NOWAIT);
+ zalloc_cpumask_var(&tick_broadcast_force_mask, GFP_NOWAIT);
+#endif
+}
Code Review / kvmfornfv.git / blobdiff