360 lines
11 KiB
C
360 lines
11 KiB
C
/* 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 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);
|
|
|
|
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 */
|