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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
#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>
struct clocksource;
struct module;
#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
#include <asm/clocksource.h>
#endif
/**
* 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.
*/
u64 (*read)(struct clocksource *cs);
u64 cycle_last;
u64 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;
u64 cs_last;
u64 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) (u64)((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(u64 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);
#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
extern void clocksource_mark_unstable(struct clocksource *cs);
#else
static inline void clocksource_mark_unstable(struct clocksource *cs) { }
#endif
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 u64 clocksource_mmio_readl_up(struct clocksource *);
extern u64 clocksource_mmio_readl_down(struct clocksource *);
extern u64 clocksource_mmio_readw_up(struct clocksource *);
extern u64 clocksource_mmio_readw_down(struct clocksource *);
extern int clocksource_mmio_init(void __iomem *, const char *,
unsigned long, int, unsigned, u64 (*)(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 */
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