236 lines
6.3 KiB
C
236 lines
6.3 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 <asm/div64.h>
|
|
#include <asm/io.h>
|
|
|
|
/* clocksource cycle base type */
|
|
typedef u64 cycle_t;
|
|
struct clocksource;
|
|
|
|
/**
|
|
* struct clocksource - hardware abstraction for a free running counter
|
|
* Provides mostly state-free accessors to the underlying hardware.
|
|
*
|
|
* @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
|
|
* @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)
|
|
* @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 mask;
|
|
u32 mult;
|
|
u32 shift;
|
|
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 cycle_interval;
|
|
u64 xtime_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;
|
|
|
|
#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
|
|
/* Watchdog related data, used by the framework */
|
|
struct list_head wd_list;
|
|
cycle_t wd_last;
|
|
#endif
|
|
};
|
|
|
|
/*
|
|
* 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
|
|
* @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_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 clocksource_read(struct clocksource *cs)
|
|
{
|
|
return cs->read();
|
|
}
|
|
|
|
/**
|
|
* cyc2ns - converts clocksource cycles to nanoseconds
|
|
* @cs: Pointer to clocksource
|
|
* @cycles: Cycles
|
|
*
|
|
* Uses the clocksource and ntp ajdustment to convert cycle_ts to nanoseconds.
|
|
*
|
|
* XXX - This could use some mult_lxl_ll() asm optimization
|
|
*/
|
|
static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles)
|
|
{
|
|
u64 ret = (u64)cycles;
|
|
ret = (ret * cs->mult) >> cs->shift;
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* clocksource_calculate_interval - Calculates a clocksource interval struct
|
|
*
|
|
* @c: Pointer to clocksource.
|
|
* @length_nsec: Desired interval length in nanoseconds.
|
|
*
|
|
* Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
|
|
* pair and interval request.
|
|
*
|
|
* Unless you're the timekeeping code, you should not be using this!
|
|
*/
|
|
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 */
|
|
tmp = length_nsec;
|
|
tmp <<= c->shift;
|
|
tmp += c->mult/2;
|
|
do_div(tmp, c->mult);
|
|
|
|
c->cycle_interval = (cycle_t)tmp;
|
|
if (c->cycle_interval == 0)
|
|
c->cycle_interval = 1;
|
|
|
|
c->xtime_interval = (u64)c->cycle_interval * c->mult;
|
|
}
|
|
|
|
|
|
/* used to install a new clocksource */
|
|
extern int clocksource_register(struct clocksource*);
|
|
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 */
|