[deliverable/linux.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 <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);
#else
static inline void update_vsyscall(struct timespec *ts, struct clocksource *c)
{
}
#endif

#endif /* _LINUX_CLOCKSOURCE_H */
Commit	Line	Data
734efb46	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>
734efb46	17	#include <asm/div64.h>
	18	#include <asm/io.h>
	19
	20	/* clocksource cycle base type */
	21	typedef u64 cycle_t;
5d8b34fd	22	struct clocksource;
734efb46	23
	24	/**
	25	* struct clocksource - hardware abstraction for a free running counter
	26	* Provides mostly state-free accessors to the underlying hardware.
	27	*
	28	* @name: ptr to clocksource name
	29	* @list: list head for registration
	30	* @rating: rating value for selection (higher is better)
	31	* To avoid rating inflation the following
	32	* list should give you a guide as to how
	33	* to assign your clocksource a rating
	34	* 1-99: Unfit for real use
	35	* Only available for bootup and testing purposes.
	36	* 100-199: Base level usability.
	37	* Functional for real use, but not desired.
	38	* 200-299: Good.
	39	* A correct and usable clocksource.
	40	* 300-399: Desired.
	41	* A reasonably fast and accurate clocksource.
	42	* 400-499: Perfect
	43	* The ideal clocksource. A must-use where
	44	* available.
	45	* @read: returns a cycle value
	46	* @mask: bitmask for two's complement
	47	* subtraction of non 64 bit counters
	48	* @mult: cycle to nanosecond multiplier
	49	* @shift: cycle to nanosecond divisor (power of two)
73b08d2a	50	* @flags: flags describing special properties
acc9a9dc	51	* @vread: vsyscall based read
b52f52a0	52	* @resume: resume function for the clocksource, if necessary
19923c19 RZ	53	* @cycle_interval: Used internally by timekeeping core, please ignore.
19923c19 RZ	54	* @xtime_interval: Used internally by timekeeping core, please ignore.
734efb46	55	*/
734efb46	56	struct clocksource {
329c8d84 ED	57	/*
	58	* First part of structure is read mostly
	59	*/
734efb46	60	char *name;
	61	struct list_head list;
	62	int rating;
	63	cycle_t (*read)(void);
	64	cycle_t mask;
	65	u32 mult;
	66	u32 shift;
73b08d2a	67	unsigned long flags;
acc9a9dc	68	cycle_t (*vread)(void);
b52f52a0	69	void (*resume)(void);
0aa366f3 TL	70	#ifdef CONFIG_IA64
	71	void fsys_mmio; / used by fsyscall asm code */
	72	#define CLKSRC_FSYS_MMIO_SET(mmio, addr) ((mmio) = (addr))
	73	#else
	74	#define CLKSRC_FSYS_MMIO_SET(mmio, addr) do { } while (0)
	75	#endif
734efb46	76
734efb46	77	/* timekeeping specific data, ignore */
329c8d84 ED	78	cycle_t cycle_interval;
	79	u64 xtime_interval;
	80	/*
	81	* Second part is written at each timer interrupt
	82	* Keep it in a different cache line to dirty no
	83	* more than one cache line.
	84	*/
	85	cycle_t cycle_last ____cacheline_aligned_in_smp;
	86	u64 xtime_nsec;
19923c19	87	s64 error;
5d8b34fd TG	88
	89	#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
	90	/* Watchdog related data, used by the framework */
	91	struct list_head wd_list;
	92	cycle_t wd_last;
	93	#endif
734efb46	94	};
734efb46	95
73b08d2a TG	96	/*
	97	* Clock source flags bits::
	98	*/
5d8b34fd TG	99	#define CLOCK_SOURCE_IS_CONTINUOUS 0x01
	100	#define CLOCK_SOURCE_MUST_VERIFY 0x02
	101
	102	#define CLOCK_SOURCE_WATCHDOG 0x10
	103	#define CLOCK_SOURCE_VALID_FOR_HRES 0x20
73b08d2a	104
7f9f303a JC	105	/* simplify initialization of mask field */
7f9f303a JC	106	#define CLOCKSOURCE_MASK(bits) (cycle_t)(bits<64 ? ((1ULL<<bits)-1) : -1)
734efb46	107
	108	/**
	109	* clocksource_khz2mult - calculates mult from khz and shift
	110	* @khz: Clocksource frequency in KHz
	111	* @shift_constant: Clocksource shift factor
	112	*
	113	* Helper functions that converts a khz counter frequency to a timsource
	114	* multiplier, given the clocksource shift value
	115	*/
	116	static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
	117	{
	118	/* khz = cyc/(Million ns)
	119	* mult/2^shift = ns/cyc
	120	* mult = ns/cyc * 2^shift
	121	* mult = 1Million/khz * 2^shift
	122	* mult = 1000000 * 2^shift / khz
	123	* mult = (1000000<<shift) / khz
	124	*/
	125	u64 tmp = ((u64)1000000) << shift_constant;
	126
	127	tmp += khz/2; /* round for do_div */
	128	do_div(tmp, khz);
	129
	130	return (u32)tmp;
	131	}
	132
	133	/**
	134	* clocksource_hz2mult - calculates mult from hz and shift
	135	* @hz: Clocksource frequency in Hz
	136	* @shift_constant: Clocksource shift factor
	137	*
	138	* Helper functions that converts a hz counter
	139	* frequency to a timsource multiplier, given the
	140	* clocksource shift value
	141	*/
	142	static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
	143	{
	144	/* hz = cyc/(Billion ns)
	145	* mult/2^shift = ns/cyc
	146	* mult = ns/cyc * 2^shift
	147	* mult = 1Billion/hz * 2^shift
	148	* mult = 1000000000 * 2^shift / hz
	149	* mult = (1000000000<<shift) / hz
	150	*/
	151	u64 tmp = ((u64)1000000000) << shift_constant;
	152
	153	tmp += hz/2; /* round for do_div */
	154	do_div(tmp, hz);
	155
	156	return (u32)tmp;
	157	}
	158
	159	/**
a2752549	160	* clocksource_read: - Access the clocksource's current cycle value
734efb46	161	* @cs: pointer to clocksource being read
	162	*
	163	* Uses the clocksource to return the current cycle_t value
	164	*/
a2752549	165	static inline cycle_t clocksource_read(struct clocksource *cs)
734efb46	166	{
	167	return cs->read();
	168	}
	169
	170	/**
	171	* cyc2ns - converts clocksource cycles to nanoseconds
	172	* @cs: Pointer to clocksource
	173	* @cycles: Cycles
	174	*
	175	* Uses the clocksource and ntp ajdustment to convert cycle_ts to nanoseconds.
	176	*
	177	* XXX - This could use some mult_lxl_ll() asm optimization
	178	*/
	179	static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles)
	180	{
	181	u64 ret = (u64)cycles;
	182	ret = (ret * cs->mult) >> cs->shift;
	183	return ret;
	184	}
	185
	186	/**
a2752549	187	* clocksource_calculate_interval - Calculates a clocksource interval struct
734efb46	188	*
	189	* @c: Pointer to clocksource.
	190	* @length_nsec: Desired interval length in nanoseconds.
	191	*
	192	* Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
	193	* pair and interval request.
	194	*
	195	* Unless you're the timekeeping code, you should not be using this!
	196	*/
a2752549	197	static inline void clocksource_calculate_interval(struct clocksource *c,
f5f1a24a	198	unsigned long length_nsec)
734efb46	199	{
	200	u64 tmp;
	201
	202	/* XXX - All of this could use a whole lot of optimization */
	203	tmp = length_nsec;
	204	tmp <<= c->shift;
	205	tmp += c->mult/2;
	206	do_div(tmp, c->mult);
	207
19923c19 RZ	208	c->cycle_interval = (cycle_t)tmp;
	209	if (c->cycle_interval == 0)
	210	c->cycle_interval = 1;
734efb46	211
19923c19	212	c->xtime_interval = (u64)c->cycle_interval * c->mult;
5eb6d205	213	}
	214
	215
734efb46	216	/* used to install a new clocksource */
92c7e002 TG	217	extern int clocksource_register(struct clocksource*);
	218	extern struct clocksource* clocksource_get_next(void);
	219	extern void clocksource_change_rating(struct clocksource *cs, int rating);
b52f52a0	220	extern void clocksource_resume(void);
734efb46	221
acc9a9dc	222	#ifdef CONFIG_GENERIC_TIME_VSYSCALL
	223	extern void update_vsyscall(struct timespec ts, struct clocksource c);
	224	#else
	225	static inline void update_vsyscall(struct timespec ts, struct clocksource c)
	226	{
	227	}
	228	#endif
	229
734efb46	230	#endif /* _LINUX_CLOCKSOURCE_H */