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/* 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 |
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#include <linux/types.h> |
#include <linux/timex.h> |
#include <linux/time.h> |
#include <linux/list.h> |
#include <linux/cache.h> |
#include <linux/init.h> |
#include <asm/div64.h> |
#include <asm/io.h> |
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struct clocksource; |
struct module; |
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#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
#include <asm/clocksource.h> |
#endif |
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/** |
* 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%) |
* @max_cycles: maximum safe cycle value which won't overflow on multiplication |
* @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 |
* @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 mask; |
u32 mult; |
u32 shift; |
u64 max_idle_ns; |
u32 maxadj; |
#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
struct arch_clocksource_data archdata; |
#endif |
u64 max_cycles; |
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 |
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#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 |
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/* simplify initialization of mask field */ |
#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1) |
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/** |
* 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; |
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tmp += khz/2; /* round for do_div */ |
do_div(tmp, khz); |
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return (u32)tmp; |
} |
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/** |
* 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; |
} |
|
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extern int clocksource_unregister(struct clocksource*); |
extern void clocksource_touch_watchdog(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 clocksource_default_clock(void); |
extern void clocksource_mark_unstable(struct clocksource *cs); |
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extern u64 |
clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles); |
extern void |
clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); |
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/* |
* 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_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq); |
|
/* |
* Don't call this unless you are a default clocksource |
* (AKA: jiffies) and absolutely have to. |
*/ |
static inline int __clocksource_register(struct clocksource *cs) |
{ |
return __clocksource_register_scale(cs, 1, 0); |
} |
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static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) |
{ |
return __clocksource_register_scale(cs, 1, hz); |
} |
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static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) |
{ |
return __clocksource_register_scale(cs, 1000, khz); |
} |
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static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz) |
{ |
__clocksource_update_freq_scale(cs, 1, hz); |
} |
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static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz) |
{ |
__clocksource_update_freq_scale(cs, 1000, khz); |
} |
|
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extern int timekeeping_notify(struct clocksource *clock); |
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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 *); |
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extern int clocksource_mmio_init(void __iomem *, const char *, |
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) \ |
OF_DECLARE_1(clksrc, name, compat, fn) |
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#ifdef CONFIG_CLKSRC_PROBE |
extern void clocksource_probe(void); |
#else |
static inline void clocksource_probe(void) {} |
#endif |
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#define CLOCKSOURCE_ACPI_DECLARE(name, table_id, fn) \ |
ACPI_DECLARE_PROBE_ENTRY(clksrc, name, table_id, 0, NULL, 0, fn) |
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#endif /* _LINUX_CLOCKSOURCE_H */ |