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![Viresh Kumar](/assets/img/avatar_default.png)
It is not possible for the clockevents core to know which modes (other than those with a corresponding feature flag) are supported by a particular implementation. And drivers are expected to handle transition to all modes elegantly, as ->set_mode() would be issued for them unconditionally. Now, adding support for a new mode complicates things a bit if we want to use the legacy ->set_mode() callback. We need to closely review all clockevents drivers to see if they would break on addition of a new mode. And after such reviews, it is found that we have to do non-trivial changes to most of the drivers [1]. Introduce mode-specific set_mode_*() callbacks, some of which the drivers may or may not implement. A missing callback would clearly convey the message that the corresponding mode isn't supported. A driver may still choose to keep supporting the legacy ->set_mode() callback, but ->set_mode() wouldn't be supporting any new modes beyond RESUME. If a driver wants to benefit from using a new mode, it would be required to migrate to the mode specific callbacks. The legacy ->set_mode() callback and the newly introduced mode-specific callbacks are mutually exclusive. Only one of them should be supported by the driver. Sanity check is done at the time of registration to distinguish between optional and required callbacks and to make error recovery and handling simpler. If the legacy ->set_mode() callback is provided, all mode specific ones would be ignored by the core but a warning is thrown if they are present. Call sites calling ->set_mode() directly are also updated to use __clockevents_set_mode() instead, as ->set_mode() may not be available anymore for few drivers. [1] https://lkml.org/lkml/2014/12/9/605 [2] https://lkml.org/lkml/2015/1/23/255 Suggested-by: Thomas Gleixner <tglx@linutronix.de> [2] Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com> Cc: linaro-kernel@lists.linaro.org Cc: linaro-networking@linaro.org Link: http://lkml.kernel.org/r/792d59a40423f0acffc9bb0bec9de1341a06fa02.1423788565.git.viresh.kumar@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
231 lines
7.3 KiB
C
231 lines
7.3 KiB
C
/* linux/include/linux/clockchips.h
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*
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* This file contains the structure definitions for clockchips.
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*
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* If you are not a clockchip, or the time of day code, you should
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* not be including this file!
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*/
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#ifndef _LINUX_CLOCKCHIPS_H
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#define _LINUX_CLOCKCHIPS_H
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/* Clock event notification values */
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enum clock_event_nofitiers {
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CLOCK_EVT_NOTIFY_ADD,
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CLOCK_EVT_NOTIFY_BROADCAST_ON,
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CLOCK_EVT_NOTIFY_BROADCAST_OFF,
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CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
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CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
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CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
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CLOCK_EVT_NOTIFY_SUSPEND,
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CLOCK_EVT_NOTIFY_RESUME,
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CLOCK_EVT_NOTIFY_CPU_DYING,
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CLOCK_EVT_NOTIFY_CPU_DEAD,
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};
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#ifdef CONFIG_GENERIC_CLOCKEVENTS_BUILD
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#include <linux/clocksource.h>
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#include <linux/cpumask.h>
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#include <linux/ktime.h>
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#include <linux/notifier.h>
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struct clock_event_device;
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struct module;
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/* Clock event mode commands */
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enum clock_event_mode {
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CLOCK_EVT_MODE_UNUSED = 0,
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CLOCK_EVT_MODE_SHUTDOWN,
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CLOCK_EVT_MODE_PERIODIC,
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CLOCK_EVT_MODE_ONESHOT,
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CLOCK_EVT_MODE_RESUME,
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/* Legacy ->set_mode() callback doesn't support below modes */
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};
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/*
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* Clock event features
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*/
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#define CLOCK_EVT_FEAT_PERIODIC 0x000001
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#define CLOCK_EVT_FEAT_ONESHOT 0x000002
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#define CLOCK_EVT_FEAT_KTIME 0x000004
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/*
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* x86(64) specific misfeatures:
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*
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* - Clockevent source stops in C3 State and needs broadcast support.
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* - Local APIC timer is used as a dummy device.
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*/
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#define CLOCK_EVT_FEAT_C3STOP 0x000008
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#define CLOCK_EVT_FEAT_DUMMY 0x000010
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/*
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* Core shall set the interrupt affinity dynamically in broadcast mode
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*/
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#define CLOCK_EVT_FEAT_DYNIRQ 0x000020
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#define CLOCK_EVT_FEAT_PERCPU 0x000040
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/*
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* Clockevent device is based on a hrtimer for broadcast
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*/
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#define CLOCK_EVT_FEAT_HRTIMER 0x000080
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/**
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* struct clock_event_device - clock event device descriptor
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* @event_handler: Assigned by the framework to be called by the low
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* level handler of the event source
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* @set_next_event: set next event function using a clocksource delta
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* @set_next_ktime: set next event function using a direct ktime value
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* @next_event: local storage for the next event in oneshot mode
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* @max_delta_ns: maximum delta value in ns
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* @min_delta_ns: minimum delta value in ns
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* @mult: nanosecond to cycles multiplier
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* @shift: nanoseconds to cycles divisor (power of two)
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* @mode: operating mode assigned by the management code
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* @features: features
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* @retries: number of forced programming retries
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* @set_mode: legacy set mode function, only for modes <= CLOCK_EVT_MODE_RESUME.
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* @set_mode_periodic: switch mode to periodic, if !set_mode
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* @set_mode_oneshot: switch mode to oneshot, if !set_mode
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* @set_mode_shutdown: switch mode to shutdown, if !set_mode
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* @set_mode_resume: resume clkevt device, if !set_mode
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* @broadcast: function to broadcast events
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* @min_delta_ticks: minimum delta value in ticks stored for reconfiguration
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* @max_delta_ticks: maximum delta value in ticks stored for reconfiguration
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* @name: ptr to clock event name
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* @rating: variable to rate clock event devices
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* @irq: IRQ number (only for non CPU local devices)
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* @bound_on: Bound on CPU
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* @cpumask: cpumask to indicate for which CPUs this device works
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* @list: list head for the management code
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* @owner: module reference
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*/
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struct clock_event_device {
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void (*event_handler)(struct clock_event_device *);
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int (*set_next_event)(unsigned long evt,
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struct clock_event_device *);
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int (*set_next_ktime)(ktime_t expires,
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struct clock_event_device *);
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ktime_t next_event;
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u64 max_delta_ns;
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u64 min_delta_ns;
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u32 mult;
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u32 shift;
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enum clock_event_mode mode;
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unsigned int features;
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unsigned long retries;
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/*
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* Mode transition callback(s): Only one of the two groups should be
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* defined:
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* - set_mode(), only for modes <= CLOCK_EVT_MODE_RESUME.
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* - set_mode_{shutdown|periodic|oneshot|resume}().
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*/
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void (*set_mode)(enum clock_event_mode mode,
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struct clock_event_device *);
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int (*set_mode_periodic)(struct clock_event_device *);
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int (*set_mode_oneshot)(struct clock_event_device *);
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int (*set_mode_shutdown)(struct clock_event_device *);
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int (*set_mode_resume)(struct clock_event_device *);
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void (*broadcast)(const struct cpumask *mask);
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void (*suspend)(struct clock_event_device *);
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void (*resume)(struct clock_event_device *);
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unsigned long min_delta_ticks;
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unsigned long max_delta_ticks;
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const char *name;
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int rating;
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int irq;
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int bound_on;
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const struct cpumask *cpumask;
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struct list_head list;
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struct module *owner;
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} ____cacheline_aligned;
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/*
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* Calculate a multiplication factor for scaled math, which is used to convert
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* nanoseconds based values to clock ticks:
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*
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* clock_ticks = (nanoseconds * factor) >> shift.
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*
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* div_sc is the rearranged equation to calculate a factor from a given clock
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* ticks / nanoseconds ratio:
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*
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* factor = (clock_ticks << shift) / nanoseconds
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*/
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static inline unsigned long div_sc(unsigned long ticks, unsigned long nsec,
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int shift)
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{
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uint64_t tmp = ((uint64_t)ticks) << shift;
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do_div(tmp, nsec);
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return (unsigned long) tmp;
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}
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/* Clock event layer functions */
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extern u64 clockevent_delta2ns(unsigned long latch,
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struct clock_event_device *evt);
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extern void clockevents_register_device(struct clock_event_device *dev);
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extern int clockevents_unbind_device(struct clock_event_device *ced, int cpu);
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extern void clockevents_config(struct clock_event_device *dev, u32 freq);
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extern void clockevents_config_and_register(struct clock_event_device *dev,
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u32 freq, unsigned long min_delta,
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unsigned long max_delta);
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extern int clockevents_update_freq(struct clock_event_device *ce, u32 freq);
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extern void clockevents_exchange_device(struct clock_event_device *old,
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struct clock_event_device *new);
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extern void clockevents_set_mode(struct clock_event_device *dev,
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enum clock_event_mode mode);
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extern int clockevents_program_event(struct clock_event_device *dev,
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ktime_t expires, bool force);
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extern void clockevents_handle_noop(struct clock_event_device *dev);
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static inline void
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clockevents_calc_mult_shift(struct clock_event_device *ce, u32 freq, u32 minsec)
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{
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return clocks_calc_mult_shift(&ce->mult, &ce->shift, NSEC_PER_SEC,
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freq, minsec);
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}
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extern void clockevents_suspend(void);
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extern void clockevents_resume(void);
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#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
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#ifdef CONFIG_ARCH_HAS_TICK_BROADCAST
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extern void tick_broadcast(const struct cpumask *mask);
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#else
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#define tick_broadcast NULL
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#endif
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extern int tick_receive_broadcast(void);
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#endif
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#if defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) && defined(CONFIG_TICK_ONESHOT)
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extern void tick_setup_hrtimer_broadcast(void);
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extern int tick_check_broadcast_expired(void);
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#else
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static inline int tick_check_broadcast_expired(void) { return 0; }
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static inline void tick_setup_hrtimer_broadcast(void) {};
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#endif
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#ifdef CONFIG_GENERIC_CLOCKEVENTS
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extern int clockevents_notify(unsigned long reason, void *arg);
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#else
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static inline int clockevents_notify(unsigned long reason, void *arg) { return 0; }
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#endif
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#else /* CONFIG_GENERIC_CLOCKEVENTS_BUILD */
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static inline void clockevents_suspend(void) {}
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static inline void clockevents_resume(void) {}
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static inline int clockevents_notify(unsigned long reason, void *arg) { return 0; }
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static inline int tick_check_broadcast_expired(void) { return 0; }
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static inline void tick_setup_hrtimer_broadcast(void) {};
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#endif
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#endif
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