[net-next-2.6.git] / include / linux / clocksource.h

/*  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 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
 * @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)
 * @flags:		flags describing special properties
 * @vread:		vsyscall based read
 * @resume:		resume function for the clocksource, if necessary
 */
struct clocksource {
	/*
	 * First part of structure is read mostly
	 */
	char *name;
	struct list_head list;
	int rating;
	cycle_t (*read)(struct clocksource *cs);
	int (*enable)(struct clocksource *cs);
	void (*disable)(struct clocksource *cs);
	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

	/*
	 * 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;

#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
#define CLOCK_SOURCE_UNSTABLE			0x40

/* 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
 *
 * 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;
}


/* used to install a new clocksource */
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);
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);

static inline void
clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)
{
	return clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
				      NSEC_PER_SEC, minsec);
}

#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

extern void timekeeping_notify(struct clocksource *clock);

#endif /* _LINUX_CLOCKSOURCE_H */
Commit	Line	Data
734efb46 JS	1	/* linux/include/linux/clocksource.h
	2	*
	3	* This file contains the structure definitions for clocksources.
	4	*
	5	* If you are not a clocksource, or timekeeping code, you should
	6	* not be including this file!
	7	*/
	8	#ifndef _LINUX_CLOCKSOURCE_H
	9	#define _LINUX_CLOCKSOURCE_H
	10
	11	#include <linux/types.h>
	12	#include <linux/timex.h>
	13	#include <linux/time.h>
	14	#include <linux/list.h>
329c8d84	15	#include <linux/cache.h>
5d8b34fd	16	#include <linux/timer.h>
f1b82746	17	#include <linux/init.h>
734efb46 JS	18	#include <asm/div64.h>
	19	#include <asm/io.h>
	20
	21	/* clocksource cycle base type */
	22	typedef u64 cycle_t;
5d8b34fd	23	struct clocksource;
734efb46	24
a038a353 PO	25	/**
	26	* struct cyclecounter - hardware abstraction for a free running counter
	27	* Provides completely state-free accessors to the underlying hardware.
	28	* Depending on which hardware it reads, the cycle counter may wrap
	29	* around quickly. Locking rules (if necessary) have to be defined
	30	* by the implementor and user of specific instances of this API.
	31	*
	32	* @read: returns the current cycle value
	33	* @mask: bitmask for two's complement
	34	* subtraction of non 64 bit counters,
	35	* see CLOCKSOURCE_MASK() helper macro
	36	* @mult: cycle to nanosecond multiplier
	37	* @shift: cycle to nanosecond divisor (power of two)
	38	*/
	39	struct cyclecounter {
	40	cycle_t (read)(const struct cyclecounter cc);
	41	cycle_t mask;
	42	u32 mult;
	43	u32 shift;
	44	};
	45
	46	/**
	47	* struct timecounter - layer above a %struct cyclecounter which counts nanoseconds
	48	* Contains the state needed by timecounter_read() to detect
	49	* cycle counter wrap around. Initialize with
	50	* timecounter_init(). Also used to convert cycle counts into the
	51	* corresponding nanosecond counts with timecounter_cyc2time(). Users
	52	* of this code are responsible for initializing the underlying
	53	* cycle counter hardware, locking issues and reading the time
	54	* more often than the cycle counter wraps around. The nanosecond
	55	* counter will only wrap around after ~585 years.
	56	*
	57	* @cc: the cycle counter used by this instance
	58	* @cycle_last: most recent cycle counter value seen by
	59	* timecounter_read()
	60	* @nsec: continuously increasing count
	61	*/
	62	struct timecounter {
	63	const struct cyclecounter *cc;
	64	cycle_t cycle_last;
	65	u64 nsec;
	66	};
	67
	68	/**
	69	* cyclecounter_cyc2ns - converts cycle counter cycles to nanoseconds
	70	* @tc: Pointer to cycle counter.
	71	* @cycles: Cycles
	72	*
	73	* XXX - This could use some mult_lxl_ll() asm optimization. Same code
	74	* as in cyc2ns, but with unsigned result.
	75	*/
	76	static inline u64 cyclecounter_cyc2ns(const struct cyclecounter *cc,
	77	cycle_t cycles)
	78	{
	79	u64 ret = (u64)cycles;
	80	ret = (ret * cc->mult) >> cc->shift;
	81	return ret;
	82	}
	83
	84	/**
	85	* timecounter_init - initialize a time counter
	86	* @tc: Pointer to time counter which is to be initialized/reset
	87	* @cc: A cycle counter, ready to be used.
	88	* @start_tstamp: Arbitrary initial time stamp.
89	*
90	* After this call the current cycle register (roughly) corresponds to
91	* the initial time stamp. Every call to timecounter_read() increments
92	* the time stamp counter by the number of elapsed nanoseconds.
93	*/
94	extern void timecounter_init(struct timecounter *tc,
95	const struct cyclecounter *cc,
96	u64 start_tstamp);
97
98	/**
99	* timecounter_read - return nanoseconds elapsed since timecounter_init()
100	* plus the initial time stamp
101	* @tc: Pointer to time counter.
102	*
103	* In other words, keeps track of time since the same epoch as
104	* the function which generated the initial time stamp.
105	*/
106	extern u64 timecounter_read(struct timecounter *tc);
107
108	/**
109	* timecounter_cyc2time - convert a cycle counter to same
110	* time base as values returned by
111	* timecounter_read()
112	* @tc: Pointer to time counter.
113	* @cycle: a value returned by tc->cc->read()
114	*
115	* Cycle counts that are converted correctly as long as they
116	* fall into the interval [-1/2 max cycle count, +1/2 max cycle count],
117	* with "max cycle count" == cs->mask+1.
118	*
119	* This allows conversion of cycle counter values which were generated
120	* in the past.
121	*/
122	extern u64 timecounter_cyc2time(struct timecounter *tc,
123	cycle_t cycle_tstamp);
124
734efb46 JS	125	/**
	126	* struct clocksource - hardware abstraction for a free running counter
	127	* Provides mostly state-free accessors to the underlying hardware.
a038a353	128	* This is the structure used for system time.
734efb46 JS	129	*
	130	* @name: ptr to clocksource name
	131	* @list: list head for registration
	132	* @rating: rating value for selection (higher is better)
	133	* To avoid rating inflation the following
	134	* list should give you a guide as to how
	135	* to assign your clocksource a rating
	136	* 1-99: Unfit for real use
	137	* Only available for bootup and testing purposes.
	138	* 100-199: Base level usability.
	139	* Functional for real use, but not desired.
	140	* 200-299: Good.
	141	* A correct and usable clocksource.
	142	* 300-399: Desired.
	143	* A reasonably fast and accurate clocksource.
	144	* 400-499: Perfect
	145	* The ideal clocksource. A must-use where
	146	* available.
8e19608e	147	* @read: returns a cycle value, passes clocksource as argument
4614e6ad MD	148	* @enable: optional function to enable the clocksource
4614e6ad MD	149	* @disable: optional function to disable the clocksource
734efb46 JS	150	* @mask: bitmask for two's complement
734efb46 JS	151	* subtraction of non 64 bit counters
0a544198	152	* @mult: cycle to nanosecond multiplier
734efb46	153	* @shift: cycle to nanosecond divisor (power of two)
73b08d2a	154	* @flags: flags describing special properties
acc9a9dc	155	* @vread: vsyscall based read
b52f52a0	156	* @resume: resume function for the clocksource, if necessary
734efb46 JS	157	*/
734efb46 JS	158	struct clocksource {
329c8d84 ED	159	/*
	160	* First part of structure is read mostly
	161	*/
734efb46 JS	162	char *name;
	163	struct list_head list;
	164	int rating;
8e19608e	165	cycle_t (read)(struct clocksource cs);
4614e6ad MD	166	int (enable)(struct clocksource cs);
4614e6ad MD	167	void (disable)(struct clocksource cs);
734efb46 JS	168	cycle_t mask;
	169	u32 mult;
	170	u32 shift;
73b08d2a	171	unsigned long flags;
acc9a9dc	172	cycle_t (*vread)(void);
b52f52a0	173	void (*resume)(void);
0aa366f3 TL	174	#ifdef CONFIG_IA64
	175	void fsys_mmio; / used by fsyscall asm code */
	176	#define CLKSRC_FSYS_MMIO_SET(mmio, addr) ((mmio) = (addr))
	177	#else
	178	#define CLKSRC_FSYS_MMIO_SET(mmio, addr) do { } while (0)
	179	#endif
734efb46	180
329c8d84 ED	181	/*
	182	* Second part is written at each timer interrupt
	183	* Keep it in a different cache line to dirty no
	184	* more than one cache line.
	185	*/
	186	cycle_t cycle_last ____cacheline_aligned_in_smp;
5d8b34fd TG	187
	188	#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
	189	/* Watchdog related data, used by the framework */
	190	struct list_head wd_list;
	191	cycle_t wd_last;
	192	#endif
734efb46 JS	193	};
734efb46 JS	194
73b08d2a TG	195	/*
	196	* Clock source flags bits::
	197	*/
5d8b34fd TG	198	#define CLOCK_SOURCE_IS_CONTINUOUS 0x01
	199	#define CLOCK_SOURCE_MUST_VERIFY 0x02
	200
	201	#define CLOCK_SOURCE_WATCHDOG 0x10
	202	#define CLOCK_SOURCE_VALID_FOR_HRES 0x20
c55c87c8	203	#define CLOCK_SOURCE_UNSTABLE 0x40
73b08d2a	204
7f9f303a	205	/* simplify initialization of mask field */
1d76c262	206	#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
734efb46 JS	207
	208	/**
	209	* clocksource_khz2mult - calculates mult from khz and shift
	210	* @khz: Clocksource frequency in KHz
	211	* @shift_constant: Clocksource shift factor
	212	*
	213	* Helper functions that converts a khz counter frequency to a timsource
	214	* multiplier, given the clocksource shift value
	215	*/
	216	static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
	217	{
	218	/* khz = cyc/(Million ns)
	219	* mult/2^shift = ns/cyc
	220	* mult = ns/cyc * 2^shift
	221	* mult = 1Million/khz * 2^shift
	222	* mult = 1000000 * 2^shift / khz
	223	* mult = (1000000<<shift) / khz
	224	*/
	225	u64 tmp = ((u64)1000000) << shift_constant;
	226
	227	tmp += khz/2; /* round for do_div */
	228	do_div(tmp, khz);
	229
	230	return (u32)tmp;
	231	}
	232
	233	/**
	234	* clocksource_hz2mult - calculates mult from hz and shift
	235	* @hz: Clocksource frequency in Hz
	236	* @shift_constant: Clocksource shift factor
	237	*
	238	* Helper functions that converts a hz counter
	239	* frequency to a timsource multiplier, given the
	240	* clocksource shift value
	241	*/
	242	static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
	243	{
	244	/* hz = cyc/(Billion ns)
	245	* mult/2^shift = ns/cyc
	246	* mult = ns/cyc * 2^shift
	247	* mult = 1Billion/hz * 2^shift
	248	* mult = 1000000000 * 2^shift / hz
	249	* mult = (1000000000<<shift) / hz
	250	*/
	251	u64 tmp = ((u64)1000000000) << shift_constant;
	252
	253	tmp += hz/2; /* round for do_div */
	254	do_div(tmp, hz);
	255
	256	return (u32)tmp;
	257	}
	258
734efb46	259	/**
155ec602	260	* clocksource_cyc2ns - converts clocksource cycles to nanoseconds
734efb46	261	*
155ec602	262	* Converts cycles to nanoseconds, using the given mult and shift.
734efb46 JS	263	*
	264	* XXX - This could use some mult_lxl_ll() asm optimization
	265	*/
155ec602	266	static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)
734efb46	267	{
155ec602	268	return ((u64) cycles * mult) >> shift;
5eb6d205 JS	269	}
	270
	271
734efb46	272	/* used to install a new clocksource */
92c7e002	273	extern int clocksource_register(struct clocksource*);
4713e22c	274	extern void clocksource_unregister(struct clocksource*);
7c3078b6	275	extern void clocksource_touch_watchdog(void);
92c7e002 TG	276	extern struct clocksource* clocksource_get_next(void);
92c7e002 TG	277	extern void clocksource_change_rating(struct clocksource *cs, int rating);
b52f52a0	278	extern void clocksource_resume(void);
f1b82746	279	extern struct clocksource * __init __weak clocksource_default_clock(void);
7285dd7f	280	extern void clocksource_mark_unstable(struct clocksource *cs);
734efb46	281
7d2f944a TG	282	extern void
	283	clocks_calc_mult_shift(u32 mult, u32 shift, u32 from, u32 to, u32 minsec);
	284
	285	static inline void
	286	clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)
	287	{
	288	return clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
	289	NSEC_PER_SEC, minsec);
	290	}
	291
acc9a9dc JS	292	#ifdef CONFIG_GENERIC_TIME_VSYSCALL
acc9a9dc JS	293	extern void update_vsyscall(struct timespec ts, struct clocksource c);
2c622148	294	extern void update_vsyscall_tz(void);
acc9a9dc JS	295	#else
	296	static inline void update_vsyscall(struct timespec ts, struct clocksource c)
	297	{
	298	}
2c622148 TB	299
	300	static inline void update_vsyscall_tz(void)
	301	{
	302	}
acc9a9dc JS	303	#endif
acc9a9dc JS	304
75c5158f MS	305	extern void timekeeping_notify(struct clocksource *clock);
75c5158f MS	306
734efb46	307	#endif /* _LINUX_CLOCKSOURCE_H */