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![Thomas Gleixner](/assets/img/avatar_default.png)
Convert locks which cannot be sleeping locks in preempt-rt to raw_spinlocks. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Ingo Molnar <mingo@elte.hu>
603 lines
15 KiB
C
603 lines
15 KiB
C
/*
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* linux/kernel/time/tick-broadcast.c
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*
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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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* This code is licenced under the GPL version 2. For details see
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* kernel-base/COPYING.
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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/tick.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
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* timer stops in C3 state.
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*/
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static struct tick_device tick_broadcast_device;
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/* FIXME: Use cpumask_var_t. */
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static DECLARE_BITMAP(tick_broadcast_mask, NR_CPUS);
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static DECLARE_BITMAP(tmpmask, NR_CPUS);
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static DEFINE_RAW_SPINLOCK(tick_broadcast_lock);
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static int tick_broadcast_force;
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#ifdef CONFIG_TICK_ONESHOT
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static void tick_broadcast_clear_oneshot(int cpu);
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#else
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static inline void tick_broadcast_clear_oneshot(int cpu) { }
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#endif
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/*
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* Debugging: see timer_list.c
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*/
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struct tick_device *tick_get_broadcast_device(void)
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{
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return &tick_broadcast_device;
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}
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struct cpumask *tick_get_broadcast_mask(void)
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{
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return to_cpumask(tick_broadcast_mask);
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}
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/*
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* Start the device in periodic mode
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*/
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static void tick_broadcast_start_periodic(struct clock_event_device *bc)
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{
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if (bc)
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tick_setup_periodic(bc, 1);
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}
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/*
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* Check, if the device can be utilized as broadcast device:
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*/
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int tick_check_broadcast_device(struct clock_event_device *dev)
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{
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if ((tick_broadcast_device.evtdev &&
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tick_broadcast_device.evtdev->rating >= dev->rating) ||
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(dev->features & CLOCK_EVT_FEAT_C3STOP))
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return 0;
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clockevents_exchange_device(NULL, dev);
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tick_broadcast_device.evtdev = dev;
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if (!cpumask_empty(tick_get_broadcast_mask()))
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tick_broadcast_start_periodic(dev);
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return 1;
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}
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/*
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* Check, if the device is the broadcast device
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*/
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int tick_is_broadcast_device(struct clock_event_device *dev)
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{
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return (dev && tick_broadcast_device.evtdev == dev);
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}
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/*
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* Check, if the device is disfunctional and a place holder, which
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* needs to be handled by the broadcast device.
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*/
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int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
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{
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unsigned long flags;
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int ret = 0;
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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/*
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* Devices might be registered with both periodic and oneshot
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* mode disabled. This signals, that the device needs to be
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* operated from the broadcast device and is a placeholder for
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* the cpu local device.
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*/
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if (!tick_device_is_functional(dev)) {
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dev->event_handler = tick_handle_periodic;
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cpumask_set_cpu(cpu, tick_get_broadcast_mask());
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tick_broadcast_start_periodic(tick_broadcast_device.evtdev);
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ret = 1;
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} else {
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/*
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* When the new device is not affected by the stop
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* feature and the cpu is marked in the broadcast mask
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* then clear the broadcast bit.
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*/
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if (!(dev->features & CLOCK_EVT_FEAT_C3STOP)) {
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int cpu = smp_processor_id();
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cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
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tick_broadcast_clear_oneshot(cpu);
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}
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}
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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return ret;
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}
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/*
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* Broadcast the event to the cpus, which are set in the mask (mangled).
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*/
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static void tick_do_broadcast(struct cpumask *mask)
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{
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int cpu = smp_processor_id();
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struct tick_device *td;
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/*
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* Check, if the current cpu is in the mask
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*/
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if (cpumask_test_cpu(cpu, mask)) {
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cpumask_clear_cpu(cpu, mask);
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td = &per_cpu(tick_cpu_device, cpu);
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td->evtdev->event_handler(td->evtdev);
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}
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if (!cpumask_empty(mask)) {
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/*
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* It might be necessary to actually check whether the devices
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* have different broadcast functions. For now, just use the
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* one of the first device. This works as long as we have this
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* misfeature only on x86 (lapic)
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*/
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td = &per_cpu(tick_cpu_device, cpumask_first(mask));
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td->evtdev->broadcast(mask);
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}
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}
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/*
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* Periodic broadcast:
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* - invoke the broadcast handlers
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*/
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static void tick_do_periodic_broadcast(void)
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{
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raw_spin_lock(&tick_broadcast_lock);
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cpumask_and(to_cpumask(tmpmask),
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cpu_online_mask, tick_get_broadcast_mask());
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tick_do_broadcast(to_cpumask(tmpmask));
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raw_spin_unlock(&tick_broadcast_lock);
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}
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/*
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* Event handler for periodic broadcast ticks
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*/
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static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
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{
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ktime_t next;
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tick_do_periodic_broadcast();
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/*
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* The device is in periodic mode. No reprogramming necessary:
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*/
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if (dev->mode == CLOCK_EVT_MODE_PERIODIC)
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return;
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/*
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* Setup the next period for devices, which do not have
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* periodic mode. We read dev->next_event first and add to it
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* when the event alrady expired. clockevents_program_event()
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* sets dev->next_event only when the event is really
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* programmed to the device.
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*/
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for (next = dev->next_event; ;) {
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next = ktime_add(next, tick_period);
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if (!clockevents_program_event(dev, next, ktime_get()))
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return;
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tick_do_periodic_broadcast();
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}
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}
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/*
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* Powerstate information: The system enters/leaves a state, where
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* affected devices might stop
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*/
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static void tick_do_broadcast_on_off(unsigned long *reason)
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{
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struct clock_event_device *bc, *dev;
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struct tick_device *td;
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unsigned long flags;
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int cpu, bc_stopped;
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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cpu = smp_processor_id();
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td = &per_cpu(tick_cpu_device, cpu);
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dev = td->evtdev;
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bc = tick_broadcast_device.evtdev;
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/*
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* Is the device not affected by the powerstate ?
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*/
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if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
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goto out;
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if (!tick_device_is_functional(dev))
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goto out;
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bc_stopped = cpumask_empty(tick_get_broadcast_mask());
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switch (*reason) {
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case CLOCK_EVT_NOTIFY_BROADCAST_ON:
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case CLOCK_EVT_NOTIFY_BROADCAST_FORCE:
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if (!cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
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cpumask_set_cpu(cpu, tick_get_broadcast_mask());
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if (tick_broadcast_device.mode ==
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TICKDEV_MODE_PERIODIC)
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clockevents_shutdown(dev);
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}
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if (*reason == CLOCK_EVT_NOTIFY_BROADCAST_FORCE)
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tick_broadcast_force = 1;
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break;
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case CLOCK_EVT_NOTIFY_BROADCAST_OFF:
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if (!tick_broadcast_force &&
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cpumask_test_cpu(cpu, tick_get_broadcast_mask())) {
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cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
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if (tick_broadcast_device.mode ==
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TICKDEV_MODE_PERIODIC)
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tick_setup_periodic(dev, 0);
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}
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break;
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}
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if (cpumask_empty(tick_get_broadcast_mask())) {
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if (!bc_stopped)
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clockevents_shutdown(bc);
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} else if (bc_stopped) {
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if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
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tick_broadcast_start_periodic(bc);
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else
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tick_broadcast_setup_oneshot(bc);
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}
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out:
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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}
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/*
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* Powerstate information: The system enters/leaves a state, where
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* affected devices might stop.
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*/
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void tick_broadcast_on_off(unsigned long reason, int *oncpu)
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{
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if (!cpumask_test_cpu(*oncpu, cpu_online_mask))
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printk(KERN_ERR "tick-broadcast: ignoring broadcast for "
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"offline CPU #%d\n", *oncpu);
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else
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tick_do_broadcast_on_off(&reason);
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}
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/*
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* Set the periodic handler depending on broadcast on/off
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*/
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void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
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{
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if (!broadcast)
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dev->event_handler = tick_handle_periodic;
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else
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dev->event_handler = tick_handle_periodic_broadcast;
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}
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/*
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* Remove a CPU from broadcasting
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*/
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void tick_shutdown_broadcast(unsigned int *cpup)
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{
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struct clock_event_device *bc;
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unsigned long flags;
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unsigned int cpu = *cpup;
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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bc = tick_broadcast_device.evtdev;
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cpumask_clear_cpu(cpu, tick_get_broadcast_mask());
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if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC) {
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if (bc && cpumask_empty(tick_get_broadcast_mask()))
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clockevents_shutdown(bc);
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}
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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}
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void tick_suspend_broadcast(void)
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{
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struct clock_event_device *bc;
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unsigned long flags;
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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bc = tick_broadcast_device.evtdev;
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if (bc)
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clockevents_shutdown(bc);
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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}
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int tick_resume_broadcast(void)
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{
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struct clock_event_device *bc;
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unsigned long flags;
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int broadcast = 0;
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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bc = tick_broadcast_device.evtdev;
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if (bc) {
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clockevents_set_mode(bc, CLOCK_EVT_MODE_RESUME);
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switch (tick_broadcast_device.mode) {
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case TICKDEV_MODE_PERIODIC:
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if (!cpumask_empty(tick_get_broadcast_mask()))
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tick_broadcast_start_periodic(bc);
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broadcast = cpumask_test_cpu(smp_processor_id(),
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tick_get_broadcast_mask());
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break;
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case TICKDEV_MODE_ONESHOT:
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broadcast = tick_resume_broadcast_oneshot(bc);
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break;
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}
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}
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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return broadcast;
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}
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#ifdef CONFIG_TICK_ONESHOT
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/* FIXME: use cpumask_var_t. */
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static DECLARE_BITMAP(tick_broadcast_oneshot_mask, NR_CPUS);
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/*
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* Exposed for debugging: see timer_list.c
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*/
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struct cpumask *tick_get_broadcast_oneshot_mask(void)
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{
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return to_cpumask(tick_broadcast_oneshot_mask);
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}
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static int tick_broadcast_set_event(ktime_t expires, int force)
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{
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struct clock_event_device *bc = tick_broadcast_device.evtdev;
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return tick_dev_program_event(bc, expires, force);
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}
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int tick_resume_broadcast_oneshot(struct clock_event_device *bc)
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{
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clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
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return 0;
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}
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/*
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* Called from irq_enter() when idle was interrupted to reenable the
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* per cpu device.
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*/
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void tick_check_oneshot_broadcast(int cpu)
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{
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if (cpumask_test_cpu(cpu, to_cpumask(tick_broadcast_oneshot_mask))) {
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struct tick_device *td = &per_cpu(tick_cpu_device, cpu);
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clockevents_set_mode(td->evtdev, CLOCK_EVT_MODE_ONESHOT);
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}
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}
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/*
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* Handle oneshot mode broadcasting
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*/
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static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
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{
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struct tick_device *td;
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ktime_t now, next_event;
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int cpu;
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raw_spin_lock(&tick_broadcast_lock);
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again:
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dev->next_event.tv64 = KTIME_MAX;
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next_event.tv64 = KTIME_MAX;
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cpumask_clear(to_cpumask(tmpmask));
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now = ktime_get();
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/* Find all expired events */
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for_each_cpu(cpu, tick_get_broadcast_oneshot_mask()) {
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td = &per_cpu(tick_cpu_device, cpu);
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if (td->evtdev->next_event.tv64 <= now.tv64)
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cpumask_set_cpu(cpu, to_cpumask(tmpmask));
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else if (td->evtdev->next_event.tv64 < next_event.tv64)
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next_event.tv64 = td->evtdev->next_event.tv64;
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}
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/*
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* Wakeup the cpus which have an expired event.
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*/
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tick_do_broadcast(to_cpumask(tmpmask));
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/*
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* Two reasons for reprogram:
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*
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* - The global event did not expire any CPU local
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* events. This happens in dyntick mode, as the maximum PIT
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* delta is quite small.
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*
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* - There are pending events on sleeping CPUs which were not
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* in the event mask
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*/
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if (next_event.tv64 != KTIME_MAX) {
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/*
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* Rearm the broadcast device. If event expired,
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* repeat the above
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*/
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if (tick_broadcast_set_event(next_event, 0))
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goto again;
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}
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raw_spin_unlock(&tick_broadcast_lock);
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}
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/*
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* Powerstate information: The system enters/leaves a state, where
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* affected devices might stop
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*/
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void tick_broadcast_oneshot_control(unsigned long reason)
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{
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struct clock_event_device *bc, *dev;
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struct tick_device *td;
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unsigned long flags;
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int cpu;
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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/*
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* Periodic mode does not care about the enter/exit of power
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* states
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*/
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if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
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goto out;
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bc = tick_broadcast_device.evtdev;
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cpu = smp_processor_id();
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td = &per_cpu(tick_cpu_device, cpu);
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dev = td->evtdev;
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if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
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goto out;
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if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
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if (!cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
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cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask());
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clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
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if (dev->next_event.tv64 < bc->next_event.tv64)
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tick_broadcast_set_event(dev->next_event, 1);
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}
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} else {
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if (cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
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cpumask_clear_cpu(cpu,
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tick_get_broadcast_oneshot_mask());
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clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
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if (dev->next_event.tv64 != KTIME_MAX)
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tick_program_event(dev->next_event, 1);
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}
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}
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out:
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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}
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/*
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* Reset the one shot broadcast for a cpu
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*
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* Called with tick_broadcast_lock held
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*/
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static void tick_broadcast_clear_oneshot(int cpu)
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{
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cpumask_clear_cpu(cpu, tick_get_broadcast_oneshot_mask());
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}
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static void tick_broadcast_init_next_event(struct cpumask *mask,
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ktime_t expires)
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{
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struct tick_device *td;
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int cpu;
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for_each_cpu(cpu, mask) {
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td = &per_cpu(tick_cpu_device, cpu);
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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)
|
|
{
|
|
/* Set it up only once ! */
|
|
if (bc->event_handler != tick_handle_oneshot_broadcast) {
|
|
int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
|
|
int cpu = smp_processor_id();
|
|
|
|
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;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
#endif
|