[mirror_ubuntu-zesty-kernel.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
};

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();
}

/**
 * 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 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 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>
734efb46 JS	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 JS	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 JS	55	*/
734efb46 JS	56	struct clocksource {
329c8d84 ED	57	/*
	58	* First part of structure is read mostly
	59	*/
734efb46 JS	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 JS	76
734efb46 JS	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 JS	94	};
734efb46 JS	95
7dffa3c6 RZ	96	extern struct clocksource clock; / current clocksource */
7dffa3c6 RZ	97
73b08d2a TG	98	/*
	99	* Clock source flags bits::
	100	*/
5d8b34fd TG	101	#define CLOCK_SOURCE_IS_CONTINUOUS 0x01
	102	#define CLOCK_SOURCE_MUST_VERIFY 0x02
	103
	104	#define CLOCK_SOURCE_WATCHDOG 0x10
	105	#define CLOCK_SOURCE_VALID_FOR_HRES 0x20
73b08d2a	106
7f9f303a	107	/* simplify initialization of mask field */
1d76c262	108	#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
734efb46 JS	109
	110	/**
	111	* clocksource_khz2mult - calculates mult from khz and shift
	112	* @khz: Clocksource frequency in KHz
	113	* @shift_constant: Clocksource shift factor
	114	*
	115	* Helper functions that converts a khz counter frequency to a timsource
	116	* multiplier, given the clocksource shift value
	117	*/
	118	static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
	119	{
	120	/* khz = cyc/(Million ns)
	121	* mult/2^shift = ns/cyc
	122	* mult = ns/cyc * 2^shift
	123	* mult = 1Million/khz * 2^shift
	124	* mult = 1000000 * 2^shift / khz
	125	* mult = (1000000<<shift) / khz
	126	*/
	127	u64 tmp = ((u64)1000000) << shift_constant;
	128
	129	tmp += khz/2; /* round for do_div */
	130	do_div(tmp, khz);
	131
	132	return (u32)tmp;
	133	}
	134
	135	/**
	136	* clocksource_hz2mult - calculates mult from hz and shift
	137	* @hz: Clocksource frequency in Hz
	138	* @shift_constant: Clocksource shift factor
	139	*
	140	* Helper functions that converts a hz counter
	141	* frequency to a timsource multiplier, given the
	142	* clocksource shift value
	143	*/
	144	static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
	145	{
	146	/* hz = cyc/(Billion ns)
	147	* mult/2^shift = ns/cyc
	148	* mult = ns/cyc * 2^shift
	149	* mult = 1Billion/hz * 2^shift
	150	* mult = 1000000000 * 2^shift / hz
	151	* mult = (1000000000<<shift) / hz
	152	*/
	153	u64 tmp = ((u64)1000000000) << shift_constant;
	154
	155	tmp += hz/2; /* round for do_div */
	156	do_div(tmp, hz);
	157
	158	return (u32)tmp;
	159	}
	160
	161	/**
a2752549	162	* clocksource_read: - Access the clocksource's current cycle value
734efb46 JS	163	* @cs: pointer to clocksource being read
	164	*
	165	* Uses the clocksource to return the current cycle_t value
	166	*/
a2752549	167	static inline cycle_t clocksource_read(struct clocksource *cs)
734efb46 JS	168	{
	169	return cs->read();
	170	}
	171
	172	/**
	173	* cyc2ns - converts clocksource cycles to nanoseconds
	174	* @cs: Pointer to clocksource
	175	* @cycles: Cycles
	176	*
	177	* Uses the clocksource and ntp ajdustment to convert cycle_ts to nanoseconds.
	178	*
	179	* XXX - This could use some mult_lxl_ll() asm optimization
	180	*/
	181	static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles)
	182	{
	183	u64 ret = (u64)cycles;
	184	ret = (ret * cs->mult) >> cs->shift;
	185	return ret;
	186	}
	187
	188	/**
a2752549	189	* clocksource_calculate_interval - Calculates a clocksource interval struct
734efb46 JS	190	*
	191	* @c: Pointer to clocksource.
	192	* @length_nsec: Desired interval length in nanoseconds.
	193	*
	194	* Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
	195	* pair and interval request.
	196	*
	197	* Unless you're the timekeeping code, you should not be using this!
	198	*/
a2752549	199	static inline void clocksource_calculate_interval(struct clocksource *c,
f5f1a24a	200	unsigned long length_nsec)
734efb46 JS	201	{
	202	u64 tmp;
	203
	204	/* XXX - All of this could use a whole lot of optimization */
	205	tmp = length_nsec;
	206	tmp <<= c->shift;
	207	tmp += c->mult/2;
	208	do_div(tmp, c->mult);
	209
19923c19 RZ	210	c->cycle_interval = (cycle_t)tmp;
	211	if (c->cycle_interval == 0)
	212	c->cycle_interval = 1;
734efb46	213
19923c19	214	c->xtime_interval = (u64)c->cycle_interval * c->mult;
5eb6d205 JS	215	}
	216
	217
734efb46	218	/* used to install a new clocksource */
92c7e002	219	extern int clocksource_register(struct clocksource*);
4713e22c	220	extern void clocksource_unregister(struct clocksource*);
7c3078b6	221	extern void clocksource_touch_watchdog(void);
92c7e002 TG	222	extern struct clocksource* clocksource_get_next(void);
92c7e002 TG	223	extern void clocksource_change_rating(struct clocksource *cs, int rating);
b52f52a0	224	extern void clocksource_resume(void);
734efb46	225
acc9a9dc JS	226	#ifdef CONFIG_GENERIC_TIME_VSYSCALL
acc9a9dc JS	227	extern void update_vsyscall(struct timespec ts, struct clocksource c);
2c622148	228	extern void update_vsyscall_tz(void);
acc9a9dc JS	229	#else
	230	static inline void update_vsyscall(struct timespec ts, struct clocksource c)
	231	{
	232	}
2c622148 TB	233
	234	static inline void update_vsyscall_tz(void)
	235	{
	236	}
acc9a9dc JS	237	#endif
acc9a9dc JS	238
734efb46	239	#endif /* _LINUX_CLOCKSOURCE_H */