X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=include%2Flinux%2Fclocksource.h;h=1219be4fb42e8f2a86e9e1268dfe7958fde8263c;hb=29ab23cc5d351658d01a4327d55e9106a73fd04f;hp=c4187cda0ee4dadfd0a5f49cc78fd894f59d6901;hpb=734efb467b31e56c2f9430590a9aa867ecf3eea1;p=safe%2Fjmp%2Flinux-2.6 diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index c4187cd..1219be4 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -12,15 +12,119 @@ #include #include #include +#include +#include #include #include /* clocksource cycle base type */ typedef u64 cycle_t; +struct clocksource; + +/** + * 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 + * @tc: 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: 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 @@ -39,32 +143,78 @@ typedef u64 cycle_t; * 400-499: Perfect * The ideal clocksource. A must-use where * available. - * @read: returns a cycle value + * @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 + * @mult: cycle to nanosecond multiplier (adjusted by NTP) + * @mult_orig: cycle to nanosecond multiplier (unadjusted by NTP) * @shift: cycle to nanosecond divisor (power of two) - * @update_callback: called when safe to alter clocksource values - * @is_continuous: defines if clocksource is free-running. - * @interval_cycles: Used internally by timekeeping core, please ignore. - * @interval_snsecs: Used internally by timekeeping core, please ignore. + * @flags: flags describing special properties + * @vread: vsyscall based read + * @resume: resume function for the clocksource, if necessary + * @cycle_interval: Used internally by timekeeping core, please ignore. + * @xtime_interval: Used internally by timekeeping core, please ignore. */ struct clocksource { + /* + * First part of structure is read mostly + */ char *name; struct list_head list; int rating; - cycle_t (*read)(void); + cycle_t (*read)(struct clocksource *cs); + int (*enable)(struct clocksource *cs); + void (*disable)(struct clocksource *cs); cycle_t mask; u32 mult; + u32 mult_orig; u32 shift; - int (*update_callback)(void); - int is_continuous; + unsigned long flags; + cycle_t (*vread)(void); + void (*resume)(void); +#ifdef CONFIG_IA64 + void *fsys_mmio; /* used by fsyscall asm code */ +#define CLKSRC_FSYS_MMIO_SET(mmio, addr) ((mmio) = (addr)) +#else +#define CLKSRC_FSYS_MMIO_SET(mmio, addr) do { } while (0) +#endif /* timekeeping specific data, ignore */ - cycle_t interval_cycles; - u64 interval_snsecs; + cycle_t cycle_interval; + u64 xtime_interval; + u32 raw_interval; + /* + * Second part is written at each timer interrupt + * Keep it in a different cache line to dirty no + * more than one cache line. + */ + cycle_t cycle_last ____cacheline_aligned_in_smp; + u64 xtime_nsec; + s64 error; + struct timespec raw_time; + +#ifdef CONFIG_CLOCKSOURCE_WATCHDOG + /* Watchdog related data, used by the framework */ + struct list_head wd_list; + cycle_t wd_last; +#endif }; +extern struct clocksource *clock; /* current clocksource */ + +/* + * 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 + +/* 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 @@ -118,14 +268,61 @@ static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) } /** - * read_clocksource: - Access the clocksource's current cycle value + * clocksource_read: - Access the clocksource's current cycle value * @cs: pointer to clocksource being read * * Uses the clocksource to return the current cycle_t value */ -static inline cycle_t read_clocksource(struct clocksource *cs) +static inline cycle_t clocksource_read(struct clocksource *cs) +{ + return cs->read(cs); +} + +/** + * clocksource_enable: - enable clocksource + * @cs: pointer to clocksource + * + * Enables the specified clocksource. The clocksource callback + * function should start up the hardware and setup mult and field + * members of struct clocksource to reflect hardware capabilities. + */ +static inline int clocksource_enable(struct clocksource *cs) +{ + int ret = 0; + + if (cs->enable) + ret = cs->enable(cs); + + /* + * The frequency may have changed while the clocksource + * was disabled. If so the code in ->enable() must update + * the mult value to reflect the new frequency. Make sure + * mult_orig follows this change. + */ + cs->mult_orig = cs->mult; + + return ret; +} + +/** + * clocksource_disable: - disable clocksource + * @cs: pointer to clocksource + * + * Disables the specified clocksource. The clocksource callback + * function should power down the now unused hardware block to + * save power. + */ +static inline void clocksource_disable(struct clocksource *cs) { - return cs->read(); + /* + * Save mult_orig in mult so clocksource_enable() can + * restore the value regardless if ->enable() updates + * the value of mult or not. + */ + cs->mult = cs->mult_orig; + + if (cs->disable) + cs->disable(cs); } /** @@ -145,7 +342,7 @@ static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles) } /** - * calculate_clocksource_interval - Calculates a clocksource interval struct + * clocksource_calculate_interval - Calculates a clocksource interval struct * * @c: Pointer to clocksource. * @length_nsec: Desired interval length in nanoseconds. @@ -155,27 +352,46 @@ static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles) * * Unless you're the timekeeping code, you should not be using this! */ -static inline void calculate_clocksource_interval(struct clocksource *c, - unsigned long length_nsec) +static inline void clocksource_calculate_interval(struct clocksource *c, + unsigned long length_nsec) { u64 tmp; - /* XXX - All of this could use a whole lot of optimization */ + /* Do the ns -> cycle conversion first, using original mult */ tmp = length_nsec; tmp <<= c->shift; - tmp += c->mult/2; - do_div(tmp, c->mult); + tmp += c->mult_orig/2; + do_div(tmp, c->mult_orig); - c->interval_cycles = (cycle_t)tmp; - if(c->interval_cycles == 0) - c->interval_cycles = 1; + c->cycle_interval = (cycle_t)tmp; + if (c->cycle_interval == 0) + c->cycle_interval = 1; - c->interval_snsecs = (u64)c->interval_cycles * c->mult; + /* Go back from cycles -> shifted ns, this time use ntp adjused mult */ + c->xtime_interval = (u64)c->cycle_interval * c->mult; + c->raw_interval = ((u64)c->cycle_interval * c->mult_orig) >> c->shift; } + /* used to install a new clocksource */ -int register_clocksource(struct clocksource*); -void reselect_clocksource(void); -struct clocksource* get_next_clocksource(void); +extern int clocksource_register(struct clocksource*); +extern void 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_resume(void); + +#ifdef CONFIG_GENERIC_TIME_VSYSCALL +extern void update_vsyscall(struct timespec *ts, struct clocksource *c); +extern void update_vsyscall_tz(void); +#else +static inline void update_vsyscall(struct timespec *ts, struct clocksource *c) +{ +} + +static inline void update_vsyscall_tz(void) +{ +} +#endif #endif /* _LINUX_CLOCKSOURCE_H */