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258 lines
7.6 KiB
258 lines
7.6 KiB
/* 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 <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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struct clocksource { |
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/* |
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* Hotpath data, fits in a single cache line when the |
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* clocksource itself is cacheline aligned. |
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*/ |
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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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} ____cacheline_aligned; |
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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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/** |
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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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/* khz = cyc/(Million ns) |
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* mult/2^shift = ns/cyc |
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* mult = ns/cyc * 2^shift |
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* mult = 1Million/khz * 2^shift |
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* mult = 1000000 * 2^shift / khz |
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* mult = (1000000<<shift) / khz |
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*/ |
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u64 tmp = ((u64)1000000) << shift_constant; |
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tmp += khz/2; /* round for do_div */ |
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do_div(tmp, khz); |
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return (u32)tmp; |
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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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/* hz = cyc/(Billion ns) |
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* mult/2^shift = ns/cyc |
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* mult = ns/cyc * 2^shift |
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* mult = 1Billion/hz * 2^shift |
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* mult = 1000000000 * 2^shift / hz |
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* mult = (1000000000<<shift) / hz |
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*/ |
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u64 tmp = ((u64)1000000000) << shift_constant; |
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tmp += hz/2; /* round for do_div */ |
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do_div(tmp, hz); |
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return (u32)tmp; |
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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(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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