259 lines
7.8 KiB
C
259 lines
7.8 KiB
C
/* linux/include/linux/clocksource.h
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*
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* This file contains the structure definitions for clocksources.
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*
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* If you are not a clocksource, or timekeeping code, you should
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* not be including this file!
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*/
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#ifndef _LINUX_CLOCKSOURCE_H
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#define _LINUX_CLOCKSOURCE_H
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#include <linux/types.h>
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#include <linux/timex.h>
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#include <linux/time.h>
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#include <linux/list.h>
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#include <linux/cache.h>
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#include <linux/timer.h>
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#include <linux/init.h>
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#include <linux/of.h>
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#include <asm/div64.h>
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#include <asm/io.h>
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struct clocksource;
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struct module;
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#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
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#include <asm/clocksource.h>
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#endif
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/**
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* struct clocksource - hardware abstraction for a free running counter
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* Provides mostly state-free accessors to the underlying hardware.
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* This is the structure used for system time.
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*
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* @name: ptr to clocksource name
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* @list: list head for registration
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* @rating: rating value for selection (higher is better)
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* To avoid rating inflation the following
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* list should give you a guide as to how
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* to assign your clocksource a rating
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* 1-99: Unfit for real use
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* Only available for bootup and testing purposes.
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* 100-199: Base level usability.
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* Functional for real use, but not desired.
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* 200-299: Good.
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* A correct and usable clocksource.
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* 300-399: Desired.
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* A reasonably fast and accurate clocksource.
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* 400-499: Perfect
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* The ideal clocksource. A must-use where
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* available.
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* @read: returns a cycle value, passes clocksource as argument
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* @enable: optional function to enable the clocksource
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* @disable: optional function to disable the clocksource
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* @mask: bitmask for two's complement
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* subtraction of non 64 bit counters
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* @mult: cycle to nanosecond multiplier
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* @shift: cycle to nanosecond divisor (power of two)
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* @max_idle_ns: max idle time permitted by the clocksource (nsecs)
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* @maxadj: maximum adjustment value to mult (~11%)
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* @max_cycles: maximum safe cycle value which won't overflow on multiplication
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* @flags: flags describing special properties
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* @archdata: arch-specific data
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* @suspend: suspend function for the clocksource, if necessary
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* @resume: resume function for the clocksource, if necessary
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* @owner: module reference, must be set by clocksource in modules
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*
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* Note: This struct is not used in hotpathes of the timekeeping code
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* because the timekeeper caches the hot path fields in its own data
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* structure, so no line cache alignment is required,
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*
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* The pointer to the clocksource itself is handed to the read
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* callback. If you need extra information there you can wrap struct
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* clocksource into your own struct. Depending on the amount of
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* information you need you should consider to cache line align that
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* structure.
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*/
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struct clocksource {
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cycle_t (*read)(struct clocksource *cs);
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cycle_t mask;
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u32 mult;
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u32 shift;
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u64 max_idle_ns;
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u32 maxadj;
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#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
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struct arch_clocksource_data archdata;
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#endif
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u64 max_cycles;
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const char *name;
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struct list_head list;
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int rating;
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int (*enable)(struct clocksource *cs);
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void (*disable)(struct clocksource *cs);
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unsigned long flags;
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void (*suspend)(struct clocksource *cs);
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void (*resume)(struct clocksource *cs);
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/* private: */
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#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
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/* Watchdog related data, used by the framework */
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struct list_head wd_list;
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cycle_t cs_last;
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cycle_t wd_last;
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#endif
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struct module *owner;
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};
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/*
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* Clock source flags bits::
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*/
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#define CLOCK_SOURCE_IS_CONTINUOUS 0x01
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#define CLOCK_SOURCE_MUST_VERIFY 0x02
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#define CLOCK_SOURCE_WATCHDOG 0x10
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#define CLOCK_SOURCE_VALID_FOR_HRES 0x20
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#define CLOCK_SOURCE_UNSTABLE 0x40
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#define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80
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#define CLOCK_SOURCE_RESELECT 0x100
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/* simplify initialization of mask field */
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#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
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static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from)
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{
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/* freq = cyc/from
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* mult/2^shift = ns/cyc
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* mult = ns/cyc * 2^shift
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* mult = from/freq * 2^shift
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* mult = from * 2^shift / freq
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* mult = (from<<shift) / freq
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*/
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u64 tmp = ((u64)from) << shift_constant;
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tmp += freq/2; /* round for do_div */
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do_div(tmp, freq);
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return (u32)tmp;
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}
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/**
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* clocksource_khz2mult - calculates mult from khz and shift
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* @khz: Clocksource frequency in KHz
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* @shift_constant: Clocksource shift factor
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*
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* Helper functions that converts a khz counter frequency to a timsource
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* multiplier, given the clocksource shift value
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*/
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static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
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{
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return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC);
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}
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/**
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* clocksource_hz2mult - calculates mult from hz and shift
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* @hz: Clocksource frequency in Hz
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* @shift_constant: Clocksource shift factor
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*
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* Helper functions that converts a hz counter
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* frequency to a timsource multiplier, given the
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* clocksource shift value
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*/
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static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
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{
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return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC);
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}
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/**
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* clocksource_cyc2ns - converts clocksource cycles to nanoseconds
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* @cycles: cycles
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* @mult: cycle to nanosecond multiplier
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* @shift: cycle to nanosecond divisor (power of two)
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*
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* Converts cycles to nanoseconds, using the given mult and shift.
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*
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* XXX - This could use some mult_lxl_ll() asm optimization
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*/
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static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)
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{
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return ((u64) cycles * mult) >> shift;
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}
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extern int clocksource_unregister(struct clocksource*);
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extern void clocksource_touch_watchdog(void);
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extern void clocksource_change_rating(struct clocksource *cs, int rating);
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extern void clocksource_suspend(void);
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extern void clocksource_resume(void);
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extern struct clocksource * __init clocksource_default_clock(void);
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extern void clocksource_mark_unstable(struct clocksource *cs);
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extern u64
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clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
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extern void
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clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
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/*
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* Don't call __clocksource_register_scale directly, use
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* clocksource_register_hz/khz
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*/
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extern int
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__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
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extern void
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__clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq);
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/*
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* Don't call this unless you are a default clocksource
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* (AKA: jiffies) and absolutely have to.
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*/
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static inline int __clocksource_register(struct clocksource *cs)
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{
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return __clocksource_register_scale(cs, 1, 0);
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}
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static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
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{
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return __clocksource_register_scale(cs, 1, hz);
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}
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static inline int clocksource_register_khz(struct clocksource *cs, u32 khz)
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{
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return __clocksource_register_scale(cs, 1000, khz);
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}
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static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz)
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{
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__clocksource_update_freq_scale(cs, 1, hz);
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}
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static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz)
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{
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__clocksource_update_freq_scale(cs, 1000, khz);
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}
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extern int timekeeping_notify(struct clocksource *clock);
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extern cycle_t clocksource_mmio_readl_up(struct clocksource *);
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extern cycle_t clocksource_mmio_readl_down(struct clocksource *);
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extern cycle_t clocksource_mmio_readw_up(struct clocksource *);
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extern cycle_t clocksource_mmio_readw_down(struct clocksource *);
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extern int clocksource_mmio_init(void __iomem *, const char *,
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unsigned long, int, unsigned, cycle_t (*)(struct clocksource *));
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extern int clocksource_i8253_init(void);
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#define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \
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OF_DECLARE_1_RET(clksrc, name, compat, fn)
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#ifdef CONFIG_CLKSRC_PROBE
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extern void clocksource_probe(void);
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#else
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static inline void clocksource_probe(void) {}
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#endif
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#define CLOCKSOURCE_ACPI_DECLARE(name, table_id, fn) \
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ACPI_DECLARE_PROBE_ENTRY(clksrc, name, table_id, 0, NULL, 0, fn)
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#endif /* _LINUX_CLOCKSOURCE_H */
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