// SPDX-License-Identifier: GPL-2.0
|
/*
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* This file contains functions which emulate a local clock-event
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* device via a broadcast event source.
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*
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* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
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* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
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* Copyright(C) 2006-2007, Timesys Corp., Thomas Gleixner
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*/
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#include <linux/cpu.h>
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#include <linux/err.h>
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#include <linux/hrtimer.h>
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#include <linux/interrupt.h>
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#include <linux/percpu.h>
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#include <linux/profile.h>
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#include <linux/sched.h>
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#include <linux/smp.h>
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#include <linux/module.h>
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#include "tick-internal.h"
|
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/*
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* 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;
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static cpumask_var_t tmpmask __cpumask_var_read_mostly;
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static int tick_broadcast_forced;
|
|
static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
|
|
#ifdef CONFIG_TICK_ONESHOT
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static DEFINE_PER_CPU(struct clock_event_device *, tick_oneshot_wakeup_device);
|
|
static void tick_broadcast_setup_oneshot(struct clock_event_device *bc);
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static void tick_broadcast_clear_oneshot(int cpu);
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static void tick_resume_broadcast_oneshot(struct clock_event_device *bc);
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# ifdef CONFIG_HOTPLUG_CPU
|
static void tick_broadcast_oneshot_offline(unsigned int cpu);
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# endif
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#else
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static inline void tick_broadcast_setup_oneshot(struct clock_event_device *bc) { BUG(); }
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static inline void tick_broadcast_clear_oneshot(int cpu) { }
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static inline void tick_resume_broadcast_oneshot(struct clock_event_device *bc) { }
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# ifdef CONFIG_HOTPLUG_CPU
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static inline void tick_broadcast_oneshot_offline(unsigned int cpu) { }
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# endif
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#endif
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/*
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* Debugging: see timer_list.c
|
*/
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struct tick_device *tick_get_broadcast_device(void)
|
{
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return &tick_broadcast_device;
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}
|
|
struct cpumask *tick_get_broadcast_mask(void)
|
{
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return tick_broadcast_mask;
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}
|
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static struct clock_event_device *tick_get_oneshot_wakeup_device(int cpu);
|
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const struct clock_event_device *tick_get_wakeup_device(int cpu)
|
{
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return tick_get_oneshot_wakeup_device(cpu);
|
}
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|
/*
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* Start the device in periodic mode
|
*/
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static void tick_broadcast_start_periodic(struct clock_event_device *bc)
|
{
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if (bc)
|
tick_setup_periodic(bc, 1);
|
}
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|
/*
|
* Check, if the device can be utilized as broadcast device:
|
*/
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static bool tick_check_broadcast_device(struct clock_event_device *curdev,
|
struct clock_event_device *newdev)
|
{
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if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
|
(newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
|
(newdev->features & CLOCK_EVT_FEAT_C3STOP))
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return false;
|
|
if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
|
!(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
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return false;
|
|
return !curdev || newdev->rating > curdev->rating;
|
}
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|
#ifdef CONFIG_TICK_ONESHOT
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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)
|
{
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/*
|
* 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))
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return false;
|
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if (!(newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
|
!(newdev->features & CLOCK_EVT_FEAT_ONESHOT))
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return false;
|
|
if (!cpumask_equal(newdev->cpumask, cpumask_of(cpu)))
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return false;
|
|
if (curdev && newdev->rating <= curdev->rating)
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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;
|
}
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#else
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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)
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cur->event_handler = clockevents_handle_noop;
|
tick_broadcast_device.evtdev = dev;
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if (!cpumask_empty(tick_broadcast_mask))
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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;
|
}
|
|
/*
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* 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();
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}
|
|
/*
|
* 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;
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}
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|
|
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
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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:
|
/*
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* 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);
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/*
|
* 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);
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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
|
}
|
