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345 lines
7.9 KiB
345 lines
7.9 KiB
/*
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* linux/kernel/time/clockevents.c
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*
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* This file contains functions which manage clock event devices.
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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/clockchips.h>
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#include <linux/hrtimer.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/notifier.h>
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#include <linux/smp.h>
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#include <linux/sysdev.h>
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/* The registered clock event devices */
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static LIST_HEAD(clockevent_devices);
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static LIST_HEAD(clockevents_released);
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/* Notification for clock events */
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static RAW_NOTIFIER_HEAD(clockevents_chain);
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/* Protection for the above */
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static DEFINE_SPINLOCK(clockevents_lock);
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/**
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* clockevents_delta2ns - Convert a latch value (device ticks) to nanoseconds
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* @latch: value to convert
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* @evt: pointer to clock event device descriptor
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*
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* Math helper, returns latch value converted to nanoseconds (bound checked)
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*/
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unsigned long clockevent_delta2ns(unsigned long latch,
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struct clock_event_device *evt)
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{
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u64 clc = ((u64) latch << evt->shift);
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do_div(clc, evt->mult);
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if (clc < 1000)
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clc = 1000;
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if (clc > LONG_MAX)
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clc = LONG_MAX;
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return (unsigned long) clc;
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}
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/**
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* clockevents_set_mode - set the operating mode of a clock event device
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* @dev: device to modify
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* @mode: new mode
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*
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* Must be called with interrupts disabled !
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*/
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void clockevents_set_mode(struct clock_event_device *dev,
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enum clock_event_mode mode)
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{
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if (dev->mode != mode) {
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dev->set_mode(mode, dev);
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dev->mode = mode;
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}
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}
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/**
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* clockevents_program_event - Reprogram the clock event device.
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* @expires: absolute expiry time (monotonic clock)
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*
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* Returns 0 on success, -ETIME when the event is in the past.
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*/
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int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
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ktime_t now)
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{
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unsigned long long clc;
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int64_t delta;
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delta = ktime_to_ns(ktime_sub(expires, now));
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if (delta <= 0)
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return -ETIME;
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dev->next_event = expires;
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if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
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return 0;
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if (delta > dev->max_delta_ns)
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delta = dev->max_delta_ns;
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if (delta < dev->min_delta_ns)
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delta = dev->min_delta_ns;
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clc = delta * dev->mult;
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clc >>= dev->shift;
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return dev->set_next_event((unsigned long) clc, dev);
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}
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/**
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* clockevents_register_notifier - register a clock events change listener
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*/
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int clockevents_register_notifier(struct notifier_block *nb)
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{
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int ret;
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spin_lock(&clockevents_lock);
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ret = raw_notifier_chain_register(&clockevents_chain, nb);
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spin_unlock(&clockevents_lock);
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return ret;
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}
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/**
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* clockevents_unregister_notifier - unregister a clock events change listener
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*/
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void clockevents_unregister_notifier(struct notifier_block *nb)
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{
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spin_lock(&clockevents_lock);
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raw_notifier_chain_unregister(&clockevents_chain, nb);
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spin_unlock(&clockevents_lock);
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}
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/*
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* Notify about a clock event change. Called with clockevents_lock
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* held.
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*/
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static void clockevents_do_notify(unsigned long reason, void *dev)
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{
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raw_notifier_call_chain(&clockevents_chain, reason, dev);
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}
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/*
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* Called after a notify add to make devices availble which were
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* released from the notifier call.
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*/
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static void clockevents_notify_released(void)
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{
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struct clock_event_device *dev;
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while (!list_empty(&clockevents_released)) {
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dev = list_entry(clockevents_released.next,
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struct clock_event_device, list);
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list_del(&dev->list);
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list_add(&dev->list, &clockevent_devices);
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clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
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}
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}
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/**
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* clockevents_register_device - register a clock event device
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* @dev: device to register
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*/
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void clockevents_register_device(struct clock_event_device *dev)
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{
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BUG_ON(dev->mode != CLOCK_EVT_MODE_UNUSED);
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spin_lock(&clockevents_lock);
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list_add(&dev->list, &clockevent_devices);
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clockevents_do_notify(CLOCK_EVT_NOTIFY_ADD, dev);
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clockevents_notify_released();
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spin_unlock(&clockevents_lock);
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}
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/*
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* Noop handler when we shut down an event device
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*/
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static void clockevents_handle_noop(struct clock_event_device *dev)
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{
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}
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/**
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* clockevents_exchange_device - release and request clock devices
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* @old: device to release (can be NULL)
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* @new: device to request (can be NULL)
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*
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* Called from the notifier chain. clockevents_lock is held already
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*/
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void clockevents_exchange_device(struct clock_event_device *old,
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struct clock_event_device *new)
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{
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unsigned long flags;
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local_irq_save(flags);
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/*
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* Caller releases a clock event device. We queue it into the
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* released list and do a notify add later.
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*/
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if (old) {
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old->event_handler = clockevents_handle_noop;
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clockevents_set_mode(old, CLOCK_EVT_MODE_UNUSED);
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list_del(&old->list);
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list_add(&old->list, &clockevents_released);
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}
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if (new) {
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BUG_ON(new->mode != CLOCK_EVT_MODE_UNUSED);
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clockevents_set_mode(new, CLOCK_EVT_MODE_SHUTDOWN);
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}
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local_irq_restore(flags);
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}
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/**
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* clockevents_request_device
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*/
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struct clock_event_device *clockevents_request_device(unsigned int features,
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cpumask_t cpumask)
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{
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struct clock_event_device *cur, *dev = NULL;
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struct list_head *tmp;
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spin_lock(&clockevents_lock);
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list_for_each(tmp, &clockevent_devices) {
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cur = list_entry(tmp, struct clock_event_device, list);
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if ((cur->features & features) == features &&
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cpus_equal(cpumask, cur->cpumask)) {
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if (!dev || dev->rating < cur->rating)
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dev = cur;
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}
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}
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clockevents_exchange_device(NULL, dev);
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spin_unlock(&clockevents_lock);
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return dev;
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}
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/**
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* clockevents_release_device
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*/
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void clockevents_release_device(struct clock_event_device *dev)
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{
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spin_lock(&clockevents_lock);
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clockevents_exchange_device(dev, NULL);
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clockevents_notify_released();
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spin_unlock(&clockevents_lock);
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}
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/**
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* clockevents_notify - notification about relevant events
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*/
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void clockevents_notify(unsigned long reason, void *arg)
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{
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spin_lock(&clockevents_lock);
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clockevents_do_notify(reason, arg);
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switch (reason) {
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case CLOCK_EVT_NOTIFY_CPU_DEAD:
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/*
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* Unregister the clock event devices which were
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* released from the users in the notify chain.
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*/
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while (!list_empty(&clockevents_released)) {
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struct clock_event_device *dev;
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dev = list_entry(clockevents_released.next,
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struct clock_event_device, list);
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list_del(&dev->list);
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}
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break;
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default:
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break;
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}
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spin_unlock(&clockevents_lock);
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}
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EXPORT_SYMBOL_GPL(clockevents_notify);
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#ifdef CONFIG_SYSFS
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/**
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* clockevents_show_registered - sysfs interface for listing clockevents
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* @dev: unused
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* @buf: char buffer to be filled with clock events list
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*
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* Provides sysfs interface for listing registered clock event devices
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*/
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static ssize_t clockevents_show_registered(struct sys_device *dev, char *buf)
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{
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struct list_head *tmp;
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char *p = buf;
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int cpu;
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spin_lock(&clockevents_lock);
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list_for_each(tmp, &clockevent_devices) {
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struct clock_event_device *ce;
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ce = list_entry(tmp, struct clock_event_device, list);
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p += sprintf(p, "%-20s F:%04x M:%d", ce->name,
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ce->features, ce->mode);
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p += sprintf(p, " C:");
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if (!cpus_equal(ce->cpumask, cpu_possible_map)) {
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for_each_cpu_mask(cpu, ce->cpumask)
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p += sprintf(p, " %d", cpu);
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} else {
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/*
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* FIXME: Add the cpu which is handling this sucker
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*/
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}
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p += sprintf(p, "\n");
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}
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spin_unlock(&clockevents_lock);
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return p - buf;
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}
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/*
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* Sysfs setup bits:
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*/
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static SYSDEV_ATTR(registered, 0600,
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clockevents_show_registered, NULL);
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static struct sysdev_class clockevents_sysclass = {
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set_kset_name("clockevents"),
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};
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static struct sys_device clockevents_sys_device = {
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.id = 0,
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.cls = &clockevents_sysclass,
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};
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static int __init clockevents_sysfs_init(void)
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{
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int error = sysdev_class_register(&clockevents_sysclass);
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if (!error)
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error = sysdev_register(&clockevents_sys_device);
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if (!error)
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error = sysdev_create_file(
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&clockevents_sys_device,
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&attr_registered);
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return error;
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}
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device_initcall(clockevents_sysfs_init);
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#endif
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