| /* 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> |
| |
| /* clocksource cycle base type */ |
| typedef u64 cycle_t; |
| struct clocksource; |
| struct module; |
| |
| #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
| #include <asm/clocksource.h> |
| #endif |
| |
| /** |
| * struct cyclecounter - hardware abstraction for a free running counter |
| * Provides completely state-free accessors to the underlying hardware. |
| * Depending on which hardware it reads, the cycle counter may wrap |
| * around quickly. Locking rules (if necessary) have to be defined |
| * by the implementor and user of specific instances of this API. |
| * |
| * @read: returns the current cycle value |
| * @mask: bitmask for two's complement |
| * subtraction of non 64 bit counters, |
| * see CLOCKSOURCE_MASK() helper macro |
| * @mult: cycle to nanosecond multiplier |
| * @shift: cycle to nanosecond divisor (power of two) |
| */ |
| struct cyclecounter { |
| cycle_t (*read)(const struct cyclecounter *cc); |
| cycle_t mask; |
| u32 mult; |
| u32 shift; |
| }; |
| |
| /** |
| * struct timecounter - layer above a %struct cyclecounter which counts nanoseconds |
| * Contains the state needed by timecounter_read() to detect |
| * cycle counter wrap around. Initialize with |
| * timecounter_init(). Also used to convert cycle counts into the |
| * corresponding nanosecond counts with timecounter_cyc2time(). Users |
| * of this code are responsible for initializing the underlying |
| * cycle counter hardware, locking issues and reading the time |
| * more often than the cycle counter wraps around. The nanosecond |
| * counter will only wrap around after ~585 years. |
| * |
| * @cc: the cycle counter used by this instance |
| * @cycle_last: most recent cycle counter value seen by |
| * timecounter_read() |
| * @nsec: continuously increasing count |
| */ |
| struct timecounter { |
| const struct cyclecounter *cc; |
| cycle_t cycle_last; |
| u64 nsec; |
| }; |
| |
| /** |
| * cyclecounter_cyc2ns - converts cycle counter cycles to nanoseconds |
| * @cc: Pointer to cycle counter. |
| * @cycles: Cycles |
| * |
| * XXX - This could use some mult_lxl_ll() asm optimization. Same code |
| * as in cyc2ns, but with unsigned result. |
| */ |
| static inline u64 cyclecounter_cyc2ns(const struct cyclecounter *cc, |
| cycle_t cycles) |
| { |
| u64 ret = (u64)cycles; |
| ret = (ret * cc->mult) >> cc->shift; |
| return ret; |
| } |
| |
| /** |
| * timecounter_init - initialize a time counter |
| * @tc: Pointer to time counter which is to be initialized/reset |
| * @cc: A cycle counter, ready to be used. |
| * @start_tstamp: Arbitrary initial time stamp. |
| * |
| * After this call the current cycle register (roughly) corresponds to |
| * the initial time stamp. Every call to timecounter_read() increments |
| * the time stamp counter by the number of elapsed nanoseconds. |
| */ |
| extern void timecounter_init(struct timecounter *tc, |
| const struct cyclecounter *cc, |
| u64 start_tstamp); |
| |
| /** |
| * timecounter_read - return nanoseconds elapsed since timecounter_init() |
| * plus the initial time stamp |
| * @tc: Pointer to time counter. |
| * |
| * In other words, keeps track of time since the same epoch as |
| * the function which generated the initial time stamp. |
| */ |
| extern u64 timecounter_read(struct timecounter *tc); |
| |
| /** |
| * timecounter_cyc2time - convert a cycle counter to same |
| * time base as values returned by |
| * timecounter_read() |
| * @tc: Pointer to time counter. |
| * @cycle_tstamp: a value returned by tc->cc->read() |
| * |
| * Cycle counts that are converted correctly as long as they |
| * fall into the interval [-1/2 max cycle count, +1/2 max cycle count], |
| * with "max cycle count" == cs->mask+1. |
| * |
| * This allows conversion of cycle counter values which were generated |
| * in the past. |
| */ |
| extern u64 timecounter_cyc2time(struct timecounter *tc, |
| cycle_t cycle_tstamp); |
| |
| /** |
| * 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. |
| */ |
| cycle_t (*read)(struct clocksource *cs); |
| cycle_t cycle_last; |
| cycle_t 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; |
| cycle_t cs_last; |
| cycle_t 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) (cycle_t)((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(cycle_t 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); |
| extern void clocksource_mark_unstable(struct clocksource *cs); |
| |
| extern u64 |
| clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask); |
| 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 cycle_t clocksource_mmio_readl_up(struct clocksource *); |
| extern cycle_t clocksource_mmio_readl_down(struct clocksource *); |
| extern cycle_t clocksource_mmio_readw_up(struct clocksource *); |
| extern cycle_t clocksource_mmio_readw_down(struct clocksource *); |
| |
| extern int clocksource_mmio_init(void __iomem *, const char *, |
| unsigned long, int, unsigned, cycle_t (*)(struct clocksource *)); |
| |
| extern int clocksource_i8253_init(void); |
| |
| #define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ |
| OF_DECLARE_1(clksrc, name, compat, fn) |
| |
| #ifdef CONFIG_CLKSRC_OF |
| extern void clocksource_of_init(void); |
| #else |
| static inline void clocksource_of_init(void) {} |
| #endif |
| |
| #endif /* _LINUX_CLOCKSOURCE_H */ |