Edit File: clocksource.h
/* 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 <asm/div64.h> #include <asm/io.h> struct clocksource; struct module; #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA #include <asm/clocksource.h> #endif /** * 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. * * @name: ptr to clocksource name * @list: list head for registration * @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. * @read: returns a cycle value, passes clocksource as argument * @enable: optional function to enable the clocksource * @disable: optional function to disable the clocksource * @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: max idle time permitted by the clocksource (nsecs) * @maxadj: maximum adjustment value to mult (~11%) * @flags: flags describing special properties * @archdata: arch-specific data * @suspend: suspend function for the clocksource, if necessary * @resume: resume function for the clocksource, if necessary * @cycle_last: most recent cycle counter value seen by ::read() * @owner: module reference, must be set by clocksource in modules */ struct clocksource { /* * Hotpath data, fits in a single cache line when the * clocksource itself is cacheline aligned. */ u64 (*read)(struct clocksource *cs); u64 cycle_last; u64 mask; u32 mult; u32 shift; u64 max_idle_ns; u32 maxadj; #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA struct arch_clocksource_data archdata; #endif const char *name; struct list_head list; int rating; int (*enable)(struct clocksource *cs); void (*disable)(struct clocksource *cs); unsigned long flags; void (*suspend)(struct clocksource *cs); void (*resume)(struct clocksource *cs); /* private: */ #ifdef CONFIG_CLOCKSOURCE_WATCHDOG /* Watchdog related data, used by the framework */ struct list_head wd_list; u64 cs_last; u64 wd_last; #endif struct module *owner; } ____cacheline_aligned; /* * Clock source flags bits:: */ #define CLOCK_SOURCE_IS_CONTINUOUS 0x01 #define CLOCK_SOURCE_MUST_VERIFY 0x02 #define CLOCK_SOURCE_WATCHDOG 0x10 #define CLOCK_SOURCE_VALID_FOR_HRES 0x20 #define CLOCK_SOURCE_UNSTABLE 0x40 #define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80 #define CLOCK_SOURCE_RESELECT 0x100 /* simplify initialization of mask field */ #define CLOCKSOURCE_MASK(bits) (u64)((bits) < 64 ? ((1ULL<<(bits))-1) : -1) /** * 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) { /* khz = cyc/(Million ns) * mult/2^shift = ns/cyc * mult = ns/cyc * 2^shift * mult = 1Million/khz * 2^shift * mult = 1000000 * 2^shift / khz * mult = (1000000<<shift) / khz */ u64 tmp = ((u64)1000000) << shift_constant; tmp += khz/2; /* round for do_div */ do_div(tmp, khz); return (u32)tmp; } /** * 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) { /* hz = cyc/(Billion ns) * mult/2^shift = ns/cyc * mult = ns/cyc * 2^shift * mult = 1Billion/hz * 2^shift * mult = 1000000000 * 2^shift / hz * mult = (1000000000<<shift) / hz */ u64 tmp = ((u64)1000000000) << shift_constant; tmp += hz/2; /* round for do_div */ do_div(tmp, hz); return (u32)tmp; } /** * clocksource_cyc2ns - converts clocksource cycles to nanoseconds * @cycles: cycles * @mult: cycle to nanosecond multiplier * @shift: cycle to nanosecond divisor (power of two) * * Converts cycles to nanoseconds, using the given mult and shift. * * XXX - This could use some mult_lxl_ll() asm optimization */ static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift) { return ((u64) cycles * mult) >> shift; } extern int clocksource_register(struct clocksource*); extern int clocksource_unregister(struct clocksource*); extern void clocksource_touch_watchdog(void); extern struct clocksource* clocksource_get_next(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 __weak clocksource_default_clock(void); #ifdef CONFIG_CLOCKSOURCE_WATCHDOG extern void clocksource_mark_unstable(struct clocksource *cs); #else static inline void clocksource_mark_unstable(struct clocksource *cs) { } #endif 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_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq); static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) { return __clocksource_register_scale(cs, 1, hz); } static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) { return __clocksource_register_scale(cs, 1000, khz); } static inline void __clocksource_updatefreq_hz(struct clocksource *cs, u32 hz) { __clocksource_updatefreq_scale(cs, 1, hz); } static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz) { __clocksource_updatefreq_scale(cs, 1000, khz); } 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); struct device_node; typedef void(*clocksource_of_init_fn)(struct device_node *); #ifdef CONFIG_CLKSRC_OF extern void clocksource_of_init(void); #define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ static const struct of_device_id __clksrc_of_table_##name \ __used __section(__clksrc_of_table) \ = { .compatible = compat, \ .data = (fn == (clocksource_of_init_fn)NULL) ? fn : fn } #else static inline void clocksource_of_init(void) {} #define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ static const struct of_device_id __clksrc_of_table_##name \ __attribute__((unused)) \ = { .compatible = compat, \ .data = (fn == (clocksource_of_init_fn)NULL) ? fn : fn } #endif #endif /* _LINUX_CLOCKSOURCE_H */