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- // SPDX-License-Identifier: GPL-2.0
- /*
- * 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
- */
- #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 __cpumask_var_read_mostly;
- static cpumask_var_t tick_broadcast_on __cpumask_var_read_mostly;
- static cpumask_var_t tmpmask __cpumask_var_read_mostly;
- static int tick_broadcast_forced;
- static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
- #ifdef CONFIG_TICK_ONESHOT
- static DEFINE_PER_CPU(struct clock_event_device *, tick_oneshot_wakeup_device);
- static void tick_broadcast_setup_oneshot(struct clock_event_device *bc);
- static void tick_broadcast_clear_oneshot(int cpu);
- static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
- # ifdef CONFIG_HOTPLUG_CPU
- static void tick_broadcast_oneshot_offline(unsigned int cpu);
- # endif
- #else
- static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { BUG(); }
- static inline void tick_broadcast_clear_oneshot(int cpu) { }
- static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
- # ifdef CONFIG_HOTPLUG_CPU
- static inline void tick_broadcast_oneshot_offline(unsigned int cpu) { }
- # endif
- #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;
- }
- static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu);
- const struct clock_event_device *tick_get_wakeup_device(int cpu)
- {
- return tick_get_oneshot_wakeup_device(cpu);
- }
- /*
- * 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;
- }
- #ifdef CONFIG_TICK_ONESHOT
- static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu)
- {
- return per_cpu(tick_oneshot_wakeup_device, cpu);
- }
- static void tick_oneshot_wakeup_handler(struct clock_event_device *wd)
- {
- /*
- * If we woke up early and the tick was reprogrammed in the
- * meantime then this may be spurious but harmless.
- */
- tick_receive_broadcast();
- }
- static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev,
- int cpu)
- {
- struct clock_event_device *curdev = tick_get_oneshot_wakeup_device(cpu);
- if (!newdev)
- goto set_device;
- if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
- (newdev->features & CLOCK_EVT_FEAT_C3STOP))
- return false;
- if (!(newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
- !(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
- return false;
- if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu)))
- return false;
- if (curdev && newdev->rating <= curdev->rating)
- return false;
- if (!try_module_get(newdev->owner))
- return false;
- newdev->event_handler = tick_oneshot_wakeup_handler;
- set_device:
- clockevents_exchange_device(curdev, newdev);
- per_cpu(tick_oneshot_wakeup_device, cpu) = newdev;
- return true;
- }
- #else
- static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu)
- {
- return NULL;
- }
- static bool tick_set_oneshot_wakeup_device(struct clock_event_device *newdev,
- int cpu)
- {
- return false;
- }
- #endif
- /*
- * Conditionally install/replace broadcast device
- */
- void tick_install_broadcast_device(struct clock_event_device *dev, int cpu)
- {
- struct clock_event_device *cur = tick_broadcast_device.evtdev;
- if (tick_set_oneshot_wakeup_device(dev, cpu))
- return;
- 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);
- if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
- return;
- /*
- * If the system already runs in oneshot mode, switch the newly
- * registered broadcast device to oneshot mode explicitly.
- */
- if (tick_broadcast_oneshot_active()) {
- tick_broadcast_switch_to_oneshot();
- return;
- }
- /*
- * 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.
- */
- 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 = 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;
- 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, if
- * the broadcast device exists and is not
- * hrtimer based.
- */
- if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER))
- ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
- break;
- default:
- break;
- }
- }
- raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
- return ret;
- }
- 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;
- }
- /*
- * Broadcast the event to the cpus, which are set in the mask (mangled).
- */
- static bool tick_do_broadcast(struct cpumask *mask)
- {
- int cpu = smp_processor_id();
- struct tick_device *td;
- bool local = false;
- /*
- * Check, if the current cpu is in the mask
- */
- if (cpumask_test_cpu(cpu, mask)) {
- struct clock_event_device *bc = tick_broadcast_device.evtdev;
- cpumask_clear_cpu(cpu, mask);
- /*
- * We only run the local handler, if the broadcast
- * device is not hrtimer based. Otherwise we run into
- * a hrtimer recursion.
- *
- * local timer_interrupt()
- * local_handler()
- * expire_hrtimers()
- * bc_handler()
- * local_handler()
- * expire_hrtimers()
- */
- local = !(bc->features & CLOCK_EVT_FEAT_HRTIMER);
- }
- 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);
- }
- return local;
- }
- /*
- * Periodic broadcast:
- * - invoke the broadcast handlers
- */
- static bool tick_do_periodic_broadcast(void)
- {
- cpumask_and(tmpmask, cpu_online_mask, tick_broadcast_mask);
- return tick_do_broadcast(tmpmask);
- }
- /*
- * Event handler for periodic broadcast ticks
- */
- static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
- {
- struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
- bool bc_local;
- raw_spin_lock(&tick_broadcast_lock);
- /* Handle spurious interrupts gracefully */
- if (clockevent_state_shutdown(tick_broadcast_device.evtdev)) {
- raw_spin_unlock(&tick_broadcast_lock);
- return;
- }
- bc_local = tick_do_periodic_broadcast();
- if (clockevent_state_oneshot(dev)) {
- ktime_t next = ktime_add(dev->next_event, tick_period);
- clockevents_program_event(dev, next, true);
- }
- raw_spin_unlock(&tick_broadcast_lock);
- /*
- * We run the handler of the local cpu after dropping
- * tick_broadcast_lock because the handler might deadlock when
- * trying to switch to oneshot mode.
- */
- if (bc_local)
- td->evtdev->event_handler(td->evtdev);
- }
- /**
- * 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.
- */
- void tick_broadcast_control(enum tick_broadcast_mode mode)
- {
- struct clock_event_device *bc, *dev;
- struct tick_device *td;
- int cpu, bc_stopped;
- unsigned long flags;
- /* Protects also the local clockevent device. */
- raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
- 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))
- goto out;
- if (!tick_device_is_functional(dev))
- goto out;
- 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;
- fallthrough;
- case TICK_BROADCAST_ON:
- cpumask_set_cpu(cpu, tick_broadcast_on);
- if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {
- /*
- * Only shutdown the cpu local device, if:
- *
- * - the broadcast device exists
- * - the broadcast device is not a hrtimer based one
- * - the broadcast device is in periodic mode to
- * avoid a hickup during switch to oneshot mode
- */
- if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER) &&
- 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 (cpumask_test_and_clear_cpu(cpu, tick_broadcast_mask)) {
- if (tick_broadcast_device.mode ==
- TICKDEV_MODE_PERIODIC)
- tick_setup_periodic(dev, 0);
- }
- break;
- }
- if (bc) {
- 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);
- }
- }
- out:
- raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
- }
- 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
- static void tick_shutdown_broadcast(void)
- {
- struct clock_event_device *bc = tick_broadcast_device.evtdev;
- if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
- if (bc && cpumask_empty(tick_broadcast_mask))
- clockevents_shutdown(bc);
- }
- }
- /*
- * Remove a CPU from broadcasting
- */
- void tick_broadcast_offline(unsigned int cpu)
- {
- raw_spin_lock(&tick_broadcast_lock);
- cpumask_clear_cpu(cpu, tick_broadcast_mask);
- cpumask_clear_cpu(cpu, tick_broadcast_on);
- tick_broadcast_oneshot_offline(cpu);
- tick_shutdown_broadcast();
- raw_spin_unlock(&tick_broadcast_lock);
- }
- #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 __cpumask_var_read_mostly;
- static cpumask_var_t tick_broadcast_pending_mask __cpumask_var_read_mostly;
- static cpumask_var_t tick_broadcast_force_mask __cpumask_var_read_mostly;
- /*
- * 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 void tick_broadcast_set_event(struct clock_event_device *bc, int cpu,
- ktime_t expires)
- {
- if (!clockevent_state_oneshot(bc))
- clockevents_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
- clockevents_program_event(bc, expires, 1);
- tick_broadcast_set_affinity(bc, cpumask_of(cpu));
- }
- static void tick_resume_broadcast_oneshot(struct clock_event_device *bc)
- {
- clockevents_switch_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_switch_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;
- bool bc_local;
- raw_spin_lock(&tick_broadcast_lock);
- dev->next_event = KTIME_MAX;
- next_event = KTIME_MAX;
- cpumask_clear(tmpmask);
- now = ktime_get();
- /* Find all expired events */
- for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
- /*
- * Required for !SMP because for_each_cpu() reports
- * unconditionally CPU0 as set on UP kernels.
- */
- if (!IS_ENABLED(CONFIG_SMP) &&
- cpumask_empty(tick_broadcast_oneshot_mask))
- break;
- td = &per_cpu(tick_cpu_device, cpu);
- if (td->evtdev->next_event <= now) {
- 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 < next_event) {
- next_event = td->evtdev->next_event;
- 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.
- */
- bc_local = 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 != KTIME_MAX)
- tick_broadcast_set_event(dev, next_cpu, next_event);
- raw_spin_unlock(&tick_broadcast_lock);
- if (bc_local) {
- td = this_cpu_ptr(&tick_cpu_device);
- td->evtdev->event_handler(td->evtdev);
- }
- }
- 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 == 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 < bc->next_event)
- return;
- }
- clockevents_switch_state(dev, CLOCK_EVT_STATE_SHUTDOWN);
- }
- static int ___tick_broadcast_oneshot_control(enum tick_broadcast_state state,
- struct tick_device *td,
- int cpu)
- {
- struct clock_event_device *bc, *dev = td->evtdev;
- int ret = 0;
- ktime_t now;
- raw_spin_lock(&tick_broadcast_lock);
- bc = tick_broadcast_device.evtdev;
- if (state == TICK_BROADCAST_ENTER) {
- /*
- * If the current CPU owns the hrtimer broadcast
- * mechanism, it cannot go deep idle and we do not add
- * the CPU to 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)
- goto out;
- /*
- * If the broadcast device is in periodic mode, we
- * return.
- */
- if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
- /* If it is a hrtimer based broadcast, return busy */
- if (bc->features & CLOCK_EVT_FEAT_HRTIMER)
- ret = -EBUSY;
- goto out;
- }
- if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
- WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
- /* Conditionally shut down the local timer. */
- 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; we return
- * busy, so the CPU does not try to go deep
- * idle.
- */
- if (cpumask_test_cpu(cpu, tick_broadcast_force_mask)) {
- ret = -EBUSY;
- } else if (dev->next_event < bc->next_event) {
- tick_broadcast_set_event(bc, cpu, dev->next_event);
- /*
- * In case of hrtimer broadcasts the
- * programming might have moved the
- * timer to this cpu. If yes, remove
- * us from the broadcast mask and
- * return busy.
- */
- 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_switch_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 == 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 no 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 therefore 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 <= now) {
- 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;
- }
- static int tick_oneshot_wakeup_control(enum tick_broadcast_state state,
- struct tick_device *td,
- int cpu)
- {
- struct clock_event_device *dev, *wd;
- dev = td->evtdev;
- if (td->mode != TICKDEV_MODE_ONESHOT)
- return -EINVAL;
- wd = tick_get_oneshot_wakeup_device(cpu);
- if (!wd)
- return -ENODEV;
- switch (state) {
- case TICK_BROADCAST_ENTER:
- clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT_STOPPED);
- clockevents_switch_state(wd, CLOCK_EVT_STATE_ONESHOT);
- clockevents_program_event(wd, dev->next_event, 1);
- break;
- case TICK_BROADCAST_EXIT:
- /* We may have transitioned to oneshot mode while idle */
- if (clockevent_get_state(wd) != CLOCK_EVT_STATE_ONESHOT)
- return -ENODEV;
- }
- return 0;
- }
- int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
- {
- struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
- int cpu = smp_processor_id();
- if (!tick_oneshot_wakeup_control(state, td, cpu))
- return 0;
- if (tick_broadcast_device.evtdev)
- return ___tick_broadcast_oneshot_control(state, td, cpu);
- /*
- * If there is no broadcast or wakeup device, tell the caller not
- * to go into deep idle.
- */
- return -EBUSY;
- }
- /*
- * 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
- */
- static void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
- {
- int cpu = smp_processor_id();
- if (!bc)
- return;
- /* Set it up only once ! */
- if (bc->event_handler != tick_handle_oneshot_broadcast) {
- int was_periodic = clockevent_state_periodic(bc);
- 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_switch_state(bc, CLOCK_EVT_STATE_ONESHOT);
- tick_broadcast_init_next_event(tmpmask,
- tick_next_period);
- tick_broadcast_set_event(bc, cpu, tick_next_period);
- } else
- bc->next_event = 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 dying CPU from broadcasting
- */
- static void tick_broadcast_oneshot_offline(unsigned int cpu)
- {
- if (tick_get_oneshot_wakeup_device(cpu))
- tick_set_oneshot_wakeup_device(NULL, cpu);
- /*
- * 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);
- }
- #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;
- }
- #else
- int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
- {
- struct clock_event_device *bc = tick_broadcast_device.evtdev;
- if (!bc || (bc->features & CLOCK_EVT_FEAT_HRTIMER))
- return -EBUSY;
- return 0;
- }
- #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
- }
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