[mirror_ubuntu-artful-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 <linux/init.h>
#include <linux/of.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%)
 * @max_cycles:		maximum safe cycle value which won't overflow on multiplication
 * @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
 * @owner:		module reference, must be set by clocksource in modules
 *
 * Note: This struct is not used in hotpathes of the timekeeping code
 * because the timekeeper caches the hot path fields in its own data
 * structure, so no line cache alignment is required,
 *
 * The pointer to the clocksource itself is handed to the read
 * callback. If you need extra information there you can wrap struct
 * clocksource into your own struct. Depending on the amount of
 * information you need you should consider to cache line align that
 * structure.
 */
struct clocksource {
	cycle_t (*read)(struct clocksource *cs);
	cycle_t mask;
	u32 mult;
	u32 shift;
	u64 max_idle_ns;
	u32 maxadj;
#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
	struct arch_clocksource_data archdata;
#endif
	u64 max_cycles;
	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;
	cycle_t cs_last;
	cycle_t wd_last;
#endif
	struct module *owner;
};

/*
 * 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) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)

static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from)
{
	/*  freq = cyc/from
	 *  mult/2^shift  = ns/cyc
	 *  mult = ns/cyc * 2^shift
	 *  mult = from/freq * 2^shift
	 *  mult = from * 2^shift / freq
	 *  mult = (from<<shift) / freq
	 */
	u64 tmp = ((u64)from) << shift_constant;

	tmp += freq/2; /* round for do_div */
	do_div(tmp, freq);

	return (u32)tmp;
}

/**
 * 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)
{
	return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC);
}

/**
 * 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)
{
	return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC);
}

/**
 * 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(cycle_t cycles, u32 mult, u32 shift)
{
	return ((u64) cycles * mult) >> shift;
}


extern int clocksource_unregister(struct clocksource*);
extern void clocksource_touch_watchdog(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 clocksource_default_clock(void);
extern void clocksource_mark_unstable(struct clocksource *cs);

extern u64
clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
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_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq);

/*
 * Don't call this unless you are a default clocksource
 * (AKA: jiffies) and absolutely have to.
 */
static inline int __clocksource_register(struct clocksource *cs)
{
	return __clocksource_register_scale(cs, 1, 0);
}

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_update_freq_hz(struct clocksource *cs, u32 hz)
{
	__clocksource_update_freq_scale(cs, 1, hz);
}

static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz)
{
	__clocksource_update_freq_scale(cs, 1000, khz);
}


extern int timekeeping_notify(struct clocksource *clock);

extern cycle_t clocksource_mmio_readl_up(struct clocksource *);
extern cycle_t clocksource_mmio_readl_down(struct clocksource *);
extern cycle_t clocksource_mmio_readw_up(struct clocksource *);
extern cycle_t clocksource_mmio_readw_down(struct clocksource *);

extern int clocksource_mmio_init(void __iomem *, const char *,
	unsigned long, int, unsigned, cycle_t (*)(struct clocksource *));

extern int clocksource_i8253_init(void);

#define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \
	OF_DECLARE_1_RET(clksrc, name, compat, fn)

#ifdef CONFIG_CLKSRC_PROBE
extern void clocksource_probe(void);
#else
static inline void clocksource_probe(void) {}
#endif

#define CLOCKSOURCE_ACPI_DECLARE(name, table_id, fn)		\
	ACPI_DECLARE_PROBE_ENTRY(clksrc, name, table_id, 0, NULL, 0, fn)

#endif /* _LINUX_CLOCKSOURCE_H */
Commit	Line	Data
	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>
	15	#include <linux/cache.h>
	16	#include <linux/timer.h>
	17	#include <linux/init.h>
	18	#include <linux/of.h>
	19	#include <asm/div64.h>
	20	#include <asm/io.h>
	21
	22	struct clocksource;
	23	struct module;
	24
	25	#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
	26	#include <asm/clocksource.h>
	27	#endif
	28
	29	/**
	30	* struct clocksource - hardware abstraction for a free running counter
	31	* Provides mostly state-free accessors to the underlying hardware.
	32	* This is the structure used for system time.
	33	*
	34	* @name: ptr to clocksource name
	35	* @list: list head for registration
	36	* @rating: rating value for selection (higher is better)
	37	* To avoid rating inflation the following
	38	* list should give you a guide as to how
	39	* to assign your clocksource a rating
	40	* 1-99: Unfit for real use
	41	* Only available for bootup and testing purposes.
	42	* 100-199: Base level usability.
	43	* Functional for real use, but not desired.
	44	* 200-299: Good.
	45	* A correct and usable clocksource.
	46	* 300-399: Desired.
	47	* A reasonably fast and accurate clocksource.
	48	* 400-499: Perfect
	49	* The ideal clocksource. A must-use where
	50	* available.
	51	* @read: returns a cycle value, passes clocksource as argument
	52	* @enable: optional function to enable the clocksource
	53	* @disable: optional function to disable the clocksource
	54	* @mask: bitmask for two's complement
	55	* subtraction of non 64 bit counters
	56	* @mult: cycle to nanosecond multiplier
	57	* @shift: cycle to nanosecond divisor (power of two)
	58	* @max_idle_ns: max idle time permitted by the clocksource (nsecs)
	59	* @maxadj: maximum adjustment value to mult (~11%)
	60	* @max_cycles: maximum safe cycle value which won't overflow on multiplication
	61	* @flags: flags describing special properties
	62	* @archdata: arch-specific data
	63	* @suspend: suspend function for the clocksource, if necessary
	64	* @resume: resume function for the clocksource, if necessary
	65	* @owner: module reference, must be set by clocksource in modules
	66	*
	67	* Note: This struct is not used in hotpathes of the timekeeping code
	68	* because the timekeeper caches the hot path fields in its own data
	69	* structure, so no line cache alignment is required,
	70	*
	71	* The pointer to the clocksource itself is handed to the read
	72	* callback. If you need extra information there you can wrap struct
	73	* clocksource into your own struct. Depending on the amount of
	74	* information you need you should consider to cache line align that
	75	* structure.
	76	*/
	77	struct clocksource {
	78	cycle_t (read)(struct clocksource cs);
	79	cycle_t mask;
	80	u32 mult;
	81	u32 shift;
	82	u64 max_idle_ns;
	83	u32 maxadj;
	84	#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
	85	struct arch_clocksource_data archdata;
	86	#endif
	87	u64 max_cycles;
	88	const char *name;
	89	struct list_head list;
	90	int rating;
	91	int (enable)(struct clocksource cs);
	92	void (disable)(struct clocksource cs);
	93	unsigned long flags;
	94	void (suspend)(struct clocksource cs);
	95	void (resume)(struct clocksource cs);
	96
	97	/* private: */
	98	#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
	99	/* Watchdog related data, used by the framework */
	100	struct list_head wd_list;
	101	cycle_t cs_last;
	102	cycle_t wd_last;
	103	#endif
	104	struct module *owner;
	105	};
	106
	107	/*
	108	* Clock source flags bits::
	109	*/
	110	#define CLOCK_SOURCE_IS_CONTINUOUS 0x01
	111	#define CLOCK_SOURCE_MUST_VERIFY 0x02
	112
	113	#define CLOCK_SOURCE_WATCHDOG 0x10
	114	#define CLOCK_SOURCE_VALID_FOR_HRES 0x20
	115	#define CLOCK_SOURCE_UNSTABLE 0x40
	116	#define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80
	117	#define CLOCK_SOURCE_RESELECT 0x100
	118
	119	/* simplify initialization of mask field */
	120	#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
	121
	122	static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from)
	123	{
	124	/* freq = cyc/from
	125	* mult/2^shift = ns/cyc
	126	* mult = ns/cyc * 2^shift
	127	* mult = from/freq * 2^shift
	128	* mult = from * 2^shift / freq
	129	* mult = (from<<shift) / freq
	130	*/
	131	u64 tmp = ((u64)from) << shift_constant;
	132
	133	tmp += freq/2; /* round for do_div */
	134	do_div(tmp, freq);
	135
	136	return (u32)tmp;
	137	}
	138
	139	/**
	140	* clocksource_khz2mult - calculates mult from khz and shift
	141	* @khz: Clocksource frequency in KHz
	142	* @shift_constant: Clocksource shift factor
	143	*
	144	* Helper functions that converts a khz counter frequency to a timsource
	145	* multiplier, given the clocksource shift value
	146	*/
	147	static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
	148	{
	149	return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC);
	150	}
	151
	152	/**
	153	* clocksource_hz2mult - calculates mult from hz and shift
	154	* @hz: Clocksource frequency in Hz
	155	* @shift_constant: Clocksource shift factor
	156	*
	157	* Helper functions that converts a hz counter
	158	* frequency to a timsource multiplier, given the
	159	* clocksource shift value
	160	*/
	161	static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
	162	{
	163	return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC);
	164	}
	165
	166	/**
	167	* clocksource_cyc2ns - converts clocksource cycles to nanoseconds
	168	* @cycles: cycles
	169	* @mult: cycle to nanosecond multiplier
	170	* @shift: cycle to nanosecond divisor (power of two)
	171	*
	172	* Converts cycles to nanoseconds, using the given mult and shift.
	173	*
	174	* XXX - This could use some mult_lxl_ll() asm optimization
	175	*/
	176	static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)
	177	{
	178	return ((u64) cycles * mult) >> shift;
	179	}
	180
	181
	182	extern int clocksource_unregister(struct clocksource*);
	183	extern void clocksource_touch_watchdog(void);
	184	extern void clocksource_change_rating(struct clocksource *cs, int rating);
	185	extern void clocksource_suspend(void);
	186	extern void clocksource_resume(void);
	187	extern struct clocksource * __init clocksource_default_clock(void);
	188	extern void clocksource_mark_unstable(struct clocksource *cs);
	189
	190	extern u64
	191	clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
	192	extern void
	193	clocks_calc_mult_shift(u32 mult, u32 shift, u32 from, u32 to, u32 minsec);
	194
	195	/*
	196	* Don't call __clocksource_register_scale directly, use
	197	* clocksource_register_hz/khz
	198	*/
	199	extern int
	200	__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
	201	extern void
	202	__clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq);
	203
	204	/*
	205	* Don't call this unless you are a default clocksource
	206	* (AKA: jiffies) and absolutely have to.
	207	*/
	208	static inline int __clocksource_register(struct clocksource *cs)
	209	{
	210	return __clocksource_register_scale(cs, 1, 0);
	211	}
	212
	213	static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
	214	{
	215	return __clocksource_register_scale(cs, 1, hz);
	216	}
	217
	218	static inline int clocksource_register_khz(struct clocksource *cs, u32 khz)
	219	{
	220	return __clocksource_register_scale(cs, 1000, khz);
	221	}
	222
	223	static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz)
	224	{
	225	__clocksource_update_freq_scale(cs, 1, hz);
	226	}
	227
	228	static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz)
	229	{
	230	__clocksource_update_freq_scale(cs, 1000, khz);
	231	}
	232
	233
	234	extern int timekeeping_notify(struct clocksource *clock);
	235
	236	extern cycle_t clocksource_mmio_readl_up(struct clocksource *);
	237	extern cycle_t clocksource_mmio_readl_down(struct clocksource *);
	238	extern cycle_t clocksource_mmio_readw_up(struct clocksource *);
	239	extern cycle_t clocksource_mmio_readw_down(struct clocksource *);
	240
	241	extern int clocksource_mmio_init(void __iomem , const char ,
	242	unsigned long, int, unsigned, cycle_t ()(struct clocksource ));
	243
	244	extern int clocksource_i8253_init(void);
	245
	246	#define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \
	247	OF_DECLARE_1_RET(clksrc, name, compat, fn)
	248
	249	#ifdef CONFIG_CLKSRC_PROBE
	250	extern void clocksource_probe(void);
	251	#else
	252	static inline void clocksource_probe(void) {}
	253	#endif
	254
	255	#define CLOCKSOURCE_ACPI_DECLARE(name, table_id, fn) \
	256	ACPI_DECLARE_PROBE_ENTRY(clksrc, name, table_id, 0, NULL, 0, fn)
	257
	258	#endif /* _LINUX_CLOCKSOURCE_H */