[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 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 (adjusted by NTP)
 * @mult_orig:		cycle to nanosecond multiplier (unadjusted by NTP)
 * @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)(struct clocksource *cs);
	int (*enable)(struct clocksource *cs);
	void (*disable)(struct clocksource *cs);
	cycle_t mask;
	u32 mult;
	u32 mult_orig;
	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;
	u32	raw_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;
	struct timespec raw_time;

#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
	/* Watchdog related data, used by the framework */
	struct list_head wd_list;
	cycle_t wd_last;
#endif
};

extern struct clocksource *clock;	/* current clocksource */

/*
 * 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(cs);
}

/**
 * clocksource_enable: - enable clocksource
 * @cs:		pointer to clocksource
 *
 * Enables the specified clocksource. The clocksource callback
 * function should start up the hardware and setup mult and field
 * members of struct clocksource to reflect hardware capabilities.
 */
static inline int clocksource_enable(struct clocksource *cs)
{
	int ret = 0;

	if (cs->enable)
		ret = cs->enable(cs);

	/*
	 * The frequency may have changed while the clocksource
	 * was disabled. If so the code in ->enable() must update
	 * the mult value to reflect the new frequency. Make sure
	 * mult_orig follows this change.
	 */
	cs->mult_orig = cs->mult;

	return ret;
}

/**
 * clocksource_disable: - disable clocksource
 * @cs:		pointer to clocksource
 *
 * Disables the specified clocksource. The clocksource callback
 * function should power down the now unused hardware block to
 * save power.
 */
static inline void clocksource_disable(struct clocksource *cs)
{
	/*
	 * Save mult_orig in mult so clocksource_enable() can
	 * restore the value regardless if ->enable() updates
	 * the value of mult or not.
	 */
	cs->mult = cs->mult_orig;

	if (cs->disable)
		cs->disable(cs);
}

/**
 * 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;

	/* Do the ns -> cycle conversion first, using original mult */
	tmp = length_nsec;
	tmp <<= c->shift;
	tmp += c->mult_orig/2;
	do_div(tmp, c->mult_orig);

	c->cycle_interval = (cycle_t)tmp;
	if (c->cycle_interval == 0)
		c->cycle_interval = 1;

	/* Go back from cycles -> shifted ns, this time use ntp adjused mult */
	c->xtime_interval = (u64)c->cycle_interval * c->mult;
	c->raw_interval = ((u64)c->cycle_interval * c->mult_orig) >> c->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);

#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 */
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
a038a353 PO	24	/**
	25	* struct cyclecounter - hardware abstraction for a free running counter
	26	* Provides completely state-free accessors to the underlying hardware.
	27	* Depending on which hardware it reads, the cycle counter may wrap
	28	* around quickly. Locking rules (if necessary) have to be defined
	29	* by the implementor and user of specific instances of this API.
	30	*
	31	* @read: returns the current cycle value
	32	* @mask: bitmask for two's complement
	33	* subtraction of non 64 bit counters,
	34	* see CLOCKSOURCE_MASK() helper macro
	35	* @mult: cycle to nanosecond multiplier
	36	* @shift: cycle to nanosecond divisor (power of two)
	37	*/
	38	struct cyclecounter {
	39	cycle_t (read)(const struct cyclecounter cc);
	40	cycle_t mask;
	41	u32 mult;
	42	u32 shift;
	43	};
	44
	45	/**
	46	* struct timecounter - layer above a %struct cyclecounter which counts nanoseconds
	47	* Contains the state needed by timecounter_read() to detect
	48	* cycle counter wrap around. Initialize with
	49	* timecounter_init(). Also used to convert cycle counts into the
	50	* corresponding nanosecond counts with timecounter_cyc2time(). Users
	51	* of this code are responsible for initializing the underlying
	52	* cycle counter hardware, locking issues and reading the time
	53	* more often than the cycle counter wraps around. The nanosecond
	54	* counter will only wrap around after ~585 years.
	55	*
	56	* @cc: the cycle counter used by this instance
	57	* @cycle_last: most recent cycle counter value seen by
	58	* timecounter_read()
	59	* @nsec: continuously increasing count
	60	*/
	61	struct timecounter {
	62	const struct cyclecounter *cc;
	63	cycle_t cycle_last;
	64	u64 nsec;
	65	};
	66
	67	/**
	68	* cyclecounter_cyc2ns - converts cycle counter cycles to nanoseconds
	69	* @tc: Pointer to cycle counter.
	70	* @cycles: Cycles
	71	*
	72	* XXX - This could use some mult_lxl_ll() asm optimization. Same code
	73	* as in cyc2ns, but with unsigned result.
	74	*/
	75	static inline u64 cyclecounter_cyc2ns(const struct cyclecounter *cc,
	76	cycle_t cycles)
	77	{
	78	u64 ret = (u64)cycles;
	79	ret = (ret * cc->mult) >> cc->shift;
	80	return ret;
	81	}
	82
	83	/**
	84	* timecounter_init - initialize a time counter
	85	* @tc: Pointer to time counter which is to be initialized/reset
	86	* @cc: A cycle counter, ready to be used.
	87	* @start_tstamp: Arbitrary initial time stamp.
88	*
89	* After this call the current cycle register (roughly) corresponds to
90	* the initial time stamp. Every call to timecounter_read() increments
91	* the time stamp counter by the number of elapsed nanoseconds.
92	*/
93	extern void timecounter_init(struct timecounter *tc,
94	const struct cyclecounter *cc,
95	u64 start_tstamp);
96
97	/**
98	* timecounter_read - return nanoseconds elapsed since timecounter_init()
99	* plus the initial time stamp
100	* @tc: Pointer to time counter.
101	*
102	* In other words, keeps track of time since the same epoch as
103	* the function which generated the initial time stamp.
104	*/
105	extern u64 timecounter_read(struct timecounter *tc);
106
107	/**
108	* timecounter_cyc2time - convert a cycle counter to same
109	* time base as values returned by
110	* timecounter_read()
111	* @tc: Pointer to time counter.
112	* @cycle: a value returned by tc->cc->read()
113	*
114	* Cycle counts that are converted correctly as long as they
115	* fall into the interval [-1/2 max cycle count, +1/2 max cycle count],
116	* with "max cycle count" == cs->mask+1.
117	*
118	* This allows conversion of cycle counter values which were generated
119	* in the past.
120	*/
121	extern u64 timecounter_cyc2time(struct timecounter *tc,
122	cycle_t cycle_tstamp);
123
734efb46	124	/**
	125	* struct clocksource - hardware abstraction for a free running counter
	126	* Provides mostly state-free accessors to the underlying hardware.
a038a353	127	* This is the structure used for system time.
734efb46	128	*
	129	* @name: ptr to clocksource name
	130	* @list: list head for registration
	131	* @rating: rating value for selection (higher is better)
	132	* To avoid rating inflation the following
	133	* list should give you a guide as to how
	134	* to assign your clocksource a rating
	135	* 1-99: Unfit for real use
	136	* Only available for bootup and testing purposes.
	137	* 100-199: Base level usability.
	138	* Functional for real use, but not desired.
	139	* 200-299: Good.
	140	* A correct and usable clocksource.
	141	* 300-399: Desired.
	142	* A reasonably fast and accurate clocksource.
	143	* 400-499: Perfect
	144	* The ideal clocksource. A must-use where
	145	* available.
8e19608e	146	* @read: returns a cycle value, passes clocksource as argument
4614e6ad MD	147	* @enable: optional function to enable the clocksource
4614e6ad MD	148	* @disable: optional function to disable the clocksource
734efb46	149	* @mask: bitmask for two's complement
734efb46	150	* subtraction of non 64 bit counters
1aa5dfb7 JS	151	* @mult: cycle to nanosecond multiplier (adjusted by NTP)
1aa5dfb7 JS	152	* @mult_orig: cycle to nanosecond multiplier (unadjusted by NTP)
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
19923c19 RZ	157	* @cycle_interval: Used internally by timekeeping core, please ignore.
19923c19 RZ	158	* @xtime_interval: Used internally by timekeeping core, please ignore.
734efb46	159	*/
734efb46	160	struct clocksource {
329c8d84 ED	161	/*
	162	* First part of structure is read mostly
	163	*/
734efb46	164	char *name;
	165	struct list_head list;
	166	int rating;
8e19608e	167	cycle_t (read)(struct clocksource cs);
4614e6ad MD	168	int (enable)(struct clocksource cs);
4614e6ad MD	169	void (disable)(struct clocksource cs);
734efb46	170	cycle_t mask;
734efb46	171	u32 mult;
1aa5dfb7	172	u32 mult_orig;
734efb46	173	u32 shift;
73b08d2a	174	unsigned long flags;
acc9a9dc	175	cycle_t (*vread)(void);
b52f52a0	176	void (*resume)(void);
0aa366f3 TL	177	#ifdef CONFIG_IA64
	178	void fsys_mmio; / used by fsyscall asm code */
	179	#define CLKSRC_FSYS_MMIO_SET(mmio, addr) ((mmio) = (addr))
	180	#else
	181	#define CLKSRC_FSYS_MMIO_SET(mmio, addr) do { } while (0)
	182	#endif
734efb46	183
734efb46	184	/* timekeeping specific data, ignore */
329c8d84 ED	185	cycle_t cycle_interval;
329c8d84 ED	186	u64 xtime_interval;
2d42244a	187	u32 raw_interval;
329c8d84 ED	188	/*
	189	* Second part is written at each timer interrupt
	190	* Keep it in a different cache line to dirty no
	191	* more than one cache line.
	192	*/
	193	cycle_t cycle_last ____cacheline_aligned_in_smp;
	194	u64 xtime_nsec;
19923c19	195	s64 error;
2d42244a	196	struct timespec raw_time;
5d8b34fd TG	197
	198	#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
	199	/* Watchdog related data, used by the framework */
	200	struct list_head wd_list;
	201	cycle_t wd_last;
	202	#endif
734efb46	203	};
734efb46	204
7dffa3c6 RZ	205	extern struct clocksource clock; / current clocksource */
7dffa3c6 RZ	206
73b08d2a TG	207	/*
	208	* Clock source flags bits::
	209	*/
5d8b34fd TG	210	#define CLOCK_SOURCE_IS_CONTINUOUS 0x01
	211	#define CLOCK_SOURCE_MUST_VERIFY 0x02
	212
	213	#define CLOCK_SOURCE_WATCHDOG 0x10
	214	#define CLOCK_SOURCE_VALID_FOR_HRES 0x20
73b08d2a	215
7f9f303a	216	/* simplify initialization of mask field */
1d76c262	217	#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
734efb46	218
	219	/**
	220	* clocksource_khz2mult - calculates mult from khz and shift
	221	* @khz: Clocksource frequency in KHz
	222	* @shift_constant: Clocksource shift factor
	223	*
	224	* Helper functions that converts a khz counter frequency to a timsource
	225	* multiplier, given the clocksource shift value
	226	*/
	227	static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
	228	{
	229	/* khz = cyc/(Million ns)
	230	* mult/2^shift = ns/cyc
	231	* mult = ns/cyc * 2^shift
	232	* mult = 1Million/khz * 2^shift
	233	* mult = 1000000 * 2^shift / khz
	234	* mult = (1000000<<shift) / khz
	235	*/
	236	u64 tmp = ((u64)1000000) << shift_constant;
	237
	238	tmp += khz/2; /* round for do_div */
	239	do_div(tmp, khz);
	240
	241	return (u32)tmp;
	242	}
	243
	244	/**
	245	* clocksource_hz2mult - calculates mult from hz and shift
	246	* @hz: Clocksource frequency in Hz
	247	* @shift_constant: Clocksource shift factor
	248	*
	249	* Helper functions that converts a hz counter
	250	* frequency to a timsource multiplier, given the
	251	* clocksource shift value
	252	*/
	253	static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
	254	{
	255	/* hz = cyc/(Billion ns)
	256	* mult/2^shift = ns/cyc
	257	* mult = ns/cyc * 2^shift
	258	* mult = 1Billion/hz * 2^shift
	259	* mult = 1000000000 * 2^shift / hz
	260	* mult = (1000000000<<shift) / hz
	261	*/
	262	u64 tmp = ((u64)1000000000) << shift_constant;
	263
	264	tmp += hz/2; /* round for do_div */
	265	do_div(tmp, hz);
	266
	267	return (u32)tmp;
	268	}
	269
	270	/**
a2752549	271	* clocksource_read: - Access the clocksource's current cycle value
734efb46	272	* @cs: pointer to clocksource being read
	273	*
	274	* Uses the clocksource to return the current cycle_t value
	275	*/
a2752549	276	static inline cycle_t clocksource_read(struct clocksource *cs)
734efb46	277	{
8e19608e	278	return cs->read(cs);
734efb46	279	}
734efb46	280
4614e6ad MD	281	/**
	282	* clocksource_enable: - enable clocksource
	283	* @cs: pointer to clocksource
	284	*
	285	* Enables the specified clocksource. The clocksource callback
	286	* function should start up the hardware and setup mult and field
	287	* members of struct clocksource to reflect hardware capabilities.
	288	*/
	289	static inline int clocksource_enable(struct clocksource *cs)
	290	{
a25cbd04 MD	291	int ret = 0;
	292
	293	if (cs->enable)
	294	ret = cs->enable(cs);
	295
c7121843 MD	296	/*
	297	* The frequency may have changed while the clocksource
	298	* was disabled. If so the code in ->enable() must update
	299	* the mult value to reflect the new frequency. Make sure
	300	* mult_orig follows this change.
	301	*/
a25cbd04 MD	302	cs->mult_orig = cs->mult;
	303
	304	return ret;
4614e6ad MD	305	}
	306
	307	/**
	308	* clocksource_disable: - disable clocksource
	309	* @cs: pointer to clocksource
	310	*
	311	* Disables the specified clocksource. The clocksource callback
	312	* function should power down the now unused hardware block to
	313	* save power.
	314	*/
	315	static inline void clocksource_disable(struct clocksource *cs)
	316	{
c7121843 MD	317	/*
	318	* Save mult_orig in mult so clocksource_enable() can
	319	* restore the value regardless if ->enable() updates
	320	* the value of mult or not.
	321	*/
	322	cs->mult = cs->mult_orig;
	323
4614e6ad MD	324	if (cs->disable)
	325	cs->disable(cs);
	326	}
	327
734efb46	328	/**
	329	* cyc2ns - converts clocksource cycles to nanoseconds
	330	* @cs: Pointer to clocksource
	331	* @cycles: Cycles
	332	*
	333	* Uses the clocksource and ntp ajdustment to convert cycle_ts to nanoseconds.
	334	*
	335	* XXX - This could use some mult_lxl_ll() asm optimization
	336	*/
	337	static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles)
	338	{
	339	u64 ret = (u64)cycles;
	340	ret = (ret * cs->mult) >> cs->shift;
	341	return ret;
	342	}
	343
	344	/**
a2752549	345	* clocksource_calculate_interval - Calculates a clocksource interval struct
734efb46	346	*
	347	* @c: Pointer to clocksource.
	348	* @length_nsec: Desired interval length in nanoseconds.
	349	*
	350	* Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
	351	* pair and interval request.
	352	*
	353	* Unless you're the timekeeping code, you should not be using this!
	354	*/
a2752549	355	static inline void clocksource_calculate_interval(struct clocksource *c,
f5f1a24a	356	unsigned long length_nsec)
734efb46	357	{
	358	u64 tmp;
	359
1aa5dfb7	360	/* Do the ns -> cycle conversion first, using original mult */
734efb46	361	tmp = length_nsec;
734efb46	362	tmp <<= c->shift;
1aa5dfb7 JS	363	tmp += c->mult_orig/2;
1aa5dfb7 JS	364	do_div(tmp, c->mult_orig);
734efb46	365
19923c19 RZ	366	c->cycle_interval = (cycle_t)tmp;
	367	if (c->cycle_interval == 0)
	368	c->cycle_interval = 1;
734efb46	369
1aa5dfb7	370	/* Go back from cycles -> shifted ns, this time use ntp adjused mult */
19923c19	371	c->xtime_interval = (u64)c->cycle_interval * c->mult;
2d42244a	372	c->raw_interval = ((u64)c->cycle_interval * c->mult_orig) >> c->shift;
5eb6d205	373	}
	374
	375
734efb46	376	/* used to install a new clocksource */
92c7e002	377	extern int clocksource_register(struct clocksource*);
4713e22c	378	extern void clocksource_unregister(struct clocksource*);
7c3078b6	379	extern void clocksource_touch_watchdog(void);
92c7e002 TG	380	extern struct clocksource* clocksource_get_next(void);
92c7e002 TG	381	extern void clocksource_change_rating(struct clocksource *cs, int rating);
b52f52a0	382	extern void clocksource_resume(void);
734efb46	383
acc9a9dc	384	#ifdef CONFIG_GENERIC_TIME_VSYSCALL
acc9a9dc	385	extern void update_vsyscall(struct timespec ts, struct clocksource c);
2c622148	386	extern void update_vsyscall_tz(void);
acc9a9dc	387	#else
	388	static inline void update_vsyscall(struct timespec ts, struct clocksource c)
	389	{
	390	}
2c622148 TB	391
	392	static inline void update_vsyscall_tz(void)
	393	{
	394	}
acc9a9dc	395	#endif
acc9a9dc	396
734efb46	397	#endif /* _LINUX_CLOCKSOURCE_H */