/* SPDX-License-Identifier: GPL-2.0 */ /* linux/include/linux/clocksource.h * * This file contains the structure definitions for clocksources. * * If you are not a clocksource, or timekeeping code, you should * not be including this file! */ #ifndef _LINUX_CLOCKSOURCE_H #define _LINUX_CLOCKSOURCE_H #include <linux/types.h> #include <linux/timex.h> #include <linux/time.h> #include <linux/list.h> #include <linux/cache.h> #include <linux/timer.h> #include <linux/init.h> #include <linux/of.h> #include <linux/clocksource_ids.h> #include <asm/div64.h> #include <asm/io.h> struct clocksource_base; struct clocksource; struct module; #if defined(CONFIG_ARCH_CLOCKSOURCE_DATA) || \ defined(CONFIG_GENERIC_GETTIMEOFDAY) #include <asm/clocksource.h> #endif #include <vdso/clocksource.h> /** * struct clocksource - hardware abstraction for a free running counter * Provides mostly state-free accessors to the underlying hardware. * This is the structure used for system time. * * @read: Returns a cycle value, passes clocksource as argument * @mask: Bitmask for two's complement * subtraction of non 64 bit counters * @mult: Cycle to nanosecond multiplier * @shift: Cycle to nanosecond divisor (power of two) * @max_idle_ns: Maximum idle time permitted by the clocksource (nsecs) * @maxadj: Maximum adjustment value to mult (~11%) * @uncertainty_margin: Maximum uncertainty in nanoseconds per half second. * Zero says to use default WATCHDOG_THRESHOLD. * @archdata: Optional arch-specific data * @max_cycles: Maximum safe cycle value which won't overflow on * multiplication * @name: Pointer to clocksource name * @list: List head for registration (internal) * @freq_khz: Clocksource frequency in khz. * @rating: Rating value for selection (higher is better) * To avoid rating inflation the following * list should give you a guide as to how * to assign your clocksource a rating * 1-99: Unfit for real use * Only available for bootup and testing purposes. * 100-199: Base level usability. * Functional for real use, but not desired. * 200-299: Good. * A correct and usable clocksource. * 300-399: Desired. * A reasonably fast and accurate clocksource. * 400-499: Perfect * The ideal clocksource. A must-use where * available. * @id: Defaults to CSID_GENERIC. The id value is captured * in certain snapshot functions to allow callers to * validate the clocksource from which the snapshot was * taken. * @flags: Flags describing special properties * @base: Hardware abstraction for clock on which a clocksource * is based * @enable: Optional function to enable the clocksource * @disable: Optional function to disable the clocksource * @suspend: Optional suspend function for the clocksource * @resume: Optional resume function for the clocksource * @mark_unstable: Optional function to inform the clocksource driver that * the watchdog marked the clocksource unstable * @tick_stable: Optional function called periodically from the watchdog * code to provide stable synchronization points * @wd_list: List head to enqueue into the watchdog list (internal) * @cs_last: Last clocksource value for clocksource watchdog * @wd_last: Last watchdog value corresponding to @cs_last * @owner: Module reference, must be set by clocksource in modules * * Note: This struct is not used in hotpathes of the timekeeping code * because the timekeeper caches the hot path fields in its own data * structure, so no cache line alignment is required, * * The pointer to the clocksource itself is handed to the read * callback. If you need extra information there you can wrap struct * clocksource into your own struct. Depending on the amount of * information you need you should consider to cache line align that * structure. */ struct clocksource { … }; /* * Clock source flags bits:: */ #define CLOCK_SOURCE_IS_CONTINUOUS … #define CLOCK_SOURCE_MUST_VERIFY … #define CLOCK_SOURCE_WATCHDOG … #define CLOCK_SOURCE_VALID_FOR_HRES … #define CLOCK_SOURCE_UNSTABLE … #define CLOCK_SOURCE_SUSPEND_NONSTOP … #define CLOCK_SOURCE_RESELECT … #define CLOCK_SOURCE_VERIFY_PERCPU … /* simplify initialization of mask field */ #define CLOCKSOURCE_MASK(bits) … static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from) { … } /** * clocksource_khz2mult - calculates mult from khz and shift * @khz: Clocksource frequency in KHz * @shift_constant: Clocksource shift factor * * Helper functions that converts a khz counter frequency to a timsource * multiplier, given the clocksource shift value */ static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) { … } /** * clocksource_hz2mult - calculates mult from hz and shift * @hz: Clocksource frequency in Hz * @shift_constant: Clocksource shift factor * * Helper functions that converts a hz counter * frequency to a timsource multiplier, given the * clocksource shift value */ static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) { … } /** * clocksource_cyc2ns - converts clocksource cycles to nanoseconds * @cycles: cycles * @mult: cycle to nanosecond multiplier * @shift: cycle to nanosecond divisor (power of two) * * Converts clocksource cycles to nanoseconds, using the given @mult and @shift. * The code is optimized for performance and is not intended to work * with absolute clocksource cycles (as those will easily overflow), * but is only intended to be used with relative (delta) clocksource cycles. * * XXX - This could use some mult_lxl_ll() asm optimization */ static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift) { … } extern int clocksource_unregister(struct clocksource*); extern void clocksource_touch_watchdog(void); extern void clocksource_change_rating(struct clocksource *cs, int rating); extern void clocksource_suspend(void); extern void clocksource_resume(void); extern struct clocksource * __init clocksource_default_clock(void); extern void clocksource_mark_unstable(struct clocksource *cs); extern void clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles); extern u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 now); extern u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles); extern void clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); /* * Don't call __clocksource_register_scale directly, use * clocksource_register_hz/khz */ extern int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); extern void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq); /* * Don't call this unless you are a default clocksource * (AKA: jiffies) and absolutely have to. */ static inline int __clocksource_register(struct clocksource *cs) { … } static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) { … } static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) { … } static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz) { … } static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz) { … } #ifdef CONFIG_ARCH_CLOCKSOURCE_INIT extern void clocksource_arch_init(struct clocksource *cs); #else static inline void clocksource_arch_init(struct clocksource *cs) { } #endif extern int timekeeping_notify(struct clocksource *clock); extern u64 clocksource_mmio_readl_up(struct clocksource *); extern u64 clocksource_mmio_readl_down(struct clocksource *); extern u64 clocksource_mmio_readw_up(struct clocksource *); extern u64 clocksource_mmio_readw_down(struct clocksource *); extern int clocksource_mmio_init(void __iomem *, const char *, unsigned long, int, unsigned, u64 (*)(struct clocksource *)); extern int clocksource_i8253_init(void); #define TIMER_OF_DECLARE(name, compat, fn) … #ifdef CONFIG_TIMER_PROBE extern void timer_probe(void); #else static inline void timer_probe(void) {} #endif #define TIMER_ACPI_DECLARE(name, table_id, fn) … static inline unsigned int clocksource_get_max_watchdog_retry(void) { … } void clocksource_verify_percpu(struct clocksource *cs); /** * struct clocksource_base - hardware abstraction for clock on which a clocksource * is based * @id: Defaults to CSID_GENERIC. The id value is used for conversion * functions which require that the current clocksource is based * on a clocksource_base with a particular ID in certain snapshot * functions to allow callers to validate the clocksource from * which the snapshot was taken. * @freq_khz: Nominal frequency of the base clock in kHz * @offset: Offset between the base clock and the clocksource * @numerator: Numerator of the clock ratio between base clock and the clocksource * @denominator: Denominator of the clock ratio between base clock and the clocksource */ struct clocksource_base { … }; #endif /* _LINUX_CLOCKSOURCE_H */
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