[linux-2.6-block.git] / include / linux / jiffies.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_JIFFIES_H
#define _LINUX_JIFFIES_H

#include <linux/cache.h>
#include <linux/math64.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <asm/param.h>			/* for HZ */
#include <generated/timeconst.h>

/*
 * The following defines establish the engineering parameters of the PLL
 * model. The HZ variable establishes the timer interrupt frequency, 100 Hz
 * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the
 * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the
 * nearest power of two in order to avoid hardware multiply operations.
 */
#if HZ >= 12 && HZ < 24
# define SHIFT_HZ	4
#elif HZ >= 24 && HZ < 48
# define SHIFT_HZ	5
#elif HZ >= 48 && HZ < 96
# define SHIFT_HZ	6
#elif HZ >= 96 && HZ < 192
# define SHIFT_HZ	7
#elif HZ >= 192 && HZ < 384
# define SHIFT_HZ	8
#elif HZ >= 384 && HZ < 768
# define SHIFT_HZ	9
#elif HZ >= 768 && HZ < 1536
# define SHIFT_HZ	10
#elif HZ >= 1536 && HZ < 3072
# define SHIFT_HZ	11
#elif HZ >= 3072 && HZ < 6144
# define SHIFT_HZ	12
#elif HZ >= 6144 && HZ < 12288
# define SHIFT_HZ	13
#else
# error Invalid value of HZ.
#endif

/* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can
 * improve accuracy by shifting LSH bits, hence calculating:
 *     (NOM << LSH) / DEN
 * This however means trouble for large NOM, because (NOM << LSH) may no
 * longer fit in 32 bits. The following way of calculating this gives us
 * some slack, under the following conditions:
 *   - (NOM / DEN) fits in (32 - LSH) bits.
 *   - (NOM % DEN) fits in (32 - LSH) bits.
 */
#define SH_DIV(NOM,DEN,LSH) (   (((NOM) / (DEN)) << (LSH))              \
                             + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN))

/* LATCH is used in the interval timer and ftape setup. */
#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ)	/* For divider */

extern int register_refined_jiffies(long clock_tick_rate);

/* TICK_NSEC is the time between ticks in nsec assuming SHIFTED_HZ */
#define TICK_NSEC ((NSEC_PER_SEC+HZ/2)/HZ)

/* TICK_USEC is the time between ticks in usec assuming SHIFTED_HZ */
#define TICK_USEC ((USEC_PER_SEC + HZ/2) / HZ)

/* USER_TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
#define USER_TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)

#ifndef __jiffy_arch_data
#define __jiffy_arch_data
#endif

/*
 * The 64-bit value is not atomic - you MUST NOT read it
 * without sampling the sequence number in jiffies_lock.
 * get_jiffies_64() will do this for you as appropriate.
 */
extern u64 __cacheline_aligned_in_smp jiffies_64;
extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies;

#if (BITS_PER_LONG < 64)
u64 get_jiffies_64(void);
#else
static inline u64 get_jiffies_64(void)
{
	return (u64)jiffies;
}
#endif

/*
 *	These inlines deal with timer wrapping correctly. You are 
 *	strongly encouraged to use them
 *	1. Because people otherwise forget
 *	2. Because if the timer wrap changes in future you won't have to
 *	   alter your driver code.
 *
 * time_after(a,b) returns true if the time a is after time b.
 *
 * Do this with "<0" and ">=0" to only test the sign of the result. A
 * good compiler would generate better code (and a really good compiler
 * wouldn't care). Gcc is currently neither.
 */
#define time_after(a,b)		\
	(typecheck(unsigned long, a) && \
	 typecheck(unsigned long, b) && \
	 ((long)((b) - (a)) < 0))
#define time_before(a,b)	time_after(b,a)

#define time_after_eq(a,b)	\
	(typecheck(unsigned long, a) && \
	 typecheck(unsigned long, b) && \
	 ((long)((a) - (b)) >= 0))
#define time_before_eq(a,b)	time_after_eq(b,a)

/*
 * Calculate whether a is in the range of [b, c].
 */
#define time_in_range(a,b,c) \
	(time_after_eq(a,b) && \
	 time_before_eq(a,c))

/*
 * Calculate whether a is in the range of [b, c).
 */
#define time_in_range_open(a,b,c) \
	(time_after_eq(a,b) && \
	 time_before(a,c))

/* Same as above, but does so with platform independent 64bit types.
 * These must be used when utilizing jiffies_64 (i.e. return value of
 * get_jiffies_64() */
#define time_after64(a,b)	\
	(typecheck(__u64, a) &&	\
	 typecheck(__u64, b) && \
	 ((__s64)((b) - (a)) < 0))
#define time_before64(a,b)	time_after64(b,a)

#define time_after_eq64(a,b)	\
	(typecheck(__u64, a) && \
	 typecheck(__u64, b) && \
	 ((__s64)((a) - (b)) >= 0))
#define time_before_eq64(a,b)	time_after_eq64(b,a)

#define time_in_range64(a, b, c) \
	(time_after_eq64(a, b) && \
	 time_before_eq64(a, c))

/*
 * These four macros compare jiffies and 'a' for convenience.
 */

/* time_is_before_jiffies(a) return true if a is before jiffies */
#define time_is_before_jiffies(a) time_after(jiffies, a)
#define time_is_before_jiffies64(a) time_after64(get_jiffies_64(), a)

/* time_is_after_jiffies(a) return true if a is after jiffies */
#define time_is_after_jiffies(a) time_before(jiffies, a)
#define time_is_after_jiffies64(a) time_before64(get_jiffies_64(), a)

/* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/
#define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a)
#define time_is_before_eq_jiffies64(a) time_after_eq64(get_jiffies_64(), a)

/* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/
#define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a)
#define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a)

/*
 * Have the 32 bit jiffies value wrap 5 minutes after boot
 * so jiffies wrap bugs show up earlier.
 */
#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))

/*
 * Change timeval to jiffies, trying to avoid the
 * most obvious overflows..
 *
 * And some not so obvious.
 *
 * Note that we don't want to return LONG_MAX, because
 * for various timeout reasons we often end up having
 * to wait "jiffies+1" in order to guarantee that we wait
 * at _least_ "jiffies" - so "jiffies+1" had better still
 * be positive.
 */
#define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1)

extern unsigned long preset_lpj;

/*
 * We want to do realistic conversions of time so we need to use the same
 * values the update wall clock code uses as the jiffies size.  This value
 * is: TICK_NSEC (which is defined in timex.h).  This
 * is a constant and is in nanoseconds.  We will use scaled math
 * with a set of scales defined here as SEC_JIFFIE_SC,  USEC_JIFFIE_SC and
 * NSEC_JIFFIE_SC.  Note that these defines contain nothing but
 * constants and so are computed at compile time.  SHIFT_HZ (computed in
 * timex.h) adjusts the scaling for different HZ values.

 * Scaled math???  What is that?
 *
 * Scaled math is a way to do integer math on values that would,
 * otherwise, either overflow, underflow, or cause undesired div
 * instructions to appear in the execution path.  In short, we "scale"
 * up the operands so they take more bits (more precision, less
 * underflow), do the desired operation and then "scale" the result back
 * by the same amount.  If we do the scaling by shifting we avoid the
 * costly mpy and the dastardly div instructions.

 * Suppose, for example, we want to convert from seconds to jiffies
 * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE.  The
 * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We
 * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we
 * might calculate at compile time, however, the result will only have
 * about 3-4 bits of precision (less for smaller values of HZ).
 *
 * So, we scale as follows:
 * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE);
 * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE;
 * Then we make SCALE a power of two so:
 * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE;
 * Now we define:
 * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE))
 * jiff = (sec * SEC_CONV) >> SCALE;
 *
 * Often the math we use will expand beyond 32-bits so we tell C how to
 * do this and pass the 64-bit result of the mpy through the ">> SCALE"
 * which should take the result back to 32-bits.  We want this expansion
 * to capture as much precision as possible.  At the same time we don't
 * want to overflow so we pick the SCALE to avoid this.  In this file,
 * that means using a different scale for each range of HZ values (as
 * defined in timex.h).
 *
 * For those who want to know, gcc will give a 64-bit result from a "*"
 * operator if the result is a long long AND at least one of the
 * operands is cast to long long (usually just prior to the "*" so as
 * not to confuse it into thinking it really has a 64-bit operand,
 * which, buy the way, it can do, but it takes more code and at least 2
 * mpys).

 * We also need to be aware that one second in nanoseconds is only a
 * couple of bits away from overflowing a 32-bit word, so we MUST use
 * 64-bits to get the full range time in nanoseconds.

 */

/*
 * Here are the scales we will use.  One for seconds, nanoseconds and
 * microseconds.
 *
 * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and
 * check if the sign bit is set.  If not, we bump the shift count by 1.
 * (Gets an extra bit of precision where we can use it.)
 * We know it is set for HZ = 1024 and HZ = 100 not for 1000.
 * Haven't tested others.

 * Limits of cpp (for #if expressions) only long (no long long), but
 * then we only need the most signicant bit.
 */

#define SEC_JIFFIE_SC (31 - SHIFT_HZ)
#if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000)
#undef SEC_JIFFIE_SC
#define SEC_JIFFIE_SC (32 - SHIFT_HZ)
#endif
#define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29)
#define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\
                                TICK_NSEC -1) / (u64)TICK_NSEC))

#define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\
                                        TICK_NSEC -1) / (u64)TICK_NSEC))
/*
 * The maximum jiffie value is (MAX_INT >> 1).  Here we translate that
 * into seconds.  The 64-bit case will overflow if we are not careful,
 * so use the messy SH_DIV macro to do it.  Still all constants.
 */
#if BITS_PER_LONG < 64
# define MAX_SEC_IN_JIFFIES \
	(long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC)
#else	/* take care of overflow on 64 bits machines */
# define MAX_SEC_IN_JIFFIES \
	(SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1)

#endif

/*
 * Convert various time units to each other:
 */
extern unsigned int jiffies_to_msecs(const unsigned long j);
extern unsigned int jiffies_to_usecs(const unsigned long j);

static inline u64 jiffies_to_nsecs(const unsigned long j)
{
	return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC;
}

extern u64 jiffies64_to_nsecs(u64 j);

extern unsigned long __msecs_to_jiffies(const unsigned int m);
#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
/*
 * HZ is equal to or smaller than 1000, and 1000 is a nice round
 * multiple of HZ, divide with the factor between them, but round
 * upwards:
 */
static inline unsigned long _msecs_to_jiffies(const unsigned int m)
{
	return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
}
#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
/*
 * HZ is larger than 1000, and HZ is a nice round multiple of 1000 -
 * simply multiply with the factor between them.
 *
 * But first make sure the multiplication result cannot overflow:
 */
static inline unsigned long _msecs_to_jiffies(const unsigned int m)
{
	if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
		return MAX_JIFFY_OFFSET;
	return m * (HZ / MSEC_PER_SEC);
}
#else
/*
 * Generic case - multiply, round and divide. But first check that if
 * we are doing a net multiplication, that we wouldn't overflow:
 */
static inline unsigned long _msecs_to_jiffies(const unsigned int m)
{
	if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
		return MAX_JIFFY_OFFSET;

	return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) >> MSEC_TO_HZ_SHR32;
}
#endif
/**
 * msecs_to_jiffies: - convert milliseconds to jiffies
 * @m:	time in milliseconds
 *
 * conversion is done as follows:
 *
 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
 *
 * - 'too large' values [that would result in larger than
 *   MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
 *
 * - all other values are converted to jiffies by either multiplying
 *   the input value by a factor or dividing it with a factor and
 *   handling any 32-bit overflows.
 *   for the details see __msecs_to_jiffies()
 *
 * msecs_to_jiffies() checks for the passed in value being a constant
 * via __builtin_constant_p() allowing gcc to eliminate most of the
 * code, __msecs_to_jiffies() is called if the value passed does not
 * allow constant folding and the actual conversion must be done at
 * runtime.
 * the HZ range specific helpers _msecs_to_jiffies() are called both
 * directly here and from __msecs_to_jiffies() in the case where
 * constant folding is not possible.
 */
static __always_inline unsigned long msecs_to_jiffies(const unsigned int m)
{
	if (__builtin_constant_p(m)) {
		if ((int)m < 0)
			return MAX_JIFFY_OFFSET;
		return _msecs_to_jiffies(m);
	} else {
		return __msecs_to_jiffies(m);
	}
}

extern unsigned long __usecs_to_jiffies(const unsigned int u);
#if !(USEC_PER_SEC % HZ)
static inline unsigned long _usecs_to_jiffies(const unsigned int u)
{
	return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
}
#else
static inline unsigned long _usecs_to_jiffies(const unsigned int u)
{
	return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
		>> USEC_TO_HZ_SHR32;
}
#endif

/**
 * usecs_to_jiffies: - convert microseconds to jiffies
 * @u:	time in microseconds
 *
 * conversion is done as follows:
 *
 * - 'too large' values [that would result in larger than
 *   MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
 *
 * - all other values are converted to jiffies by either multiplying
 *   the input value by a factor or dividing it with a factor and
 *   handling any 32-bit overflows as for msecs_to_jiffies.
 *
 * usecs_to_jiffies() checks for the passed in value being a constant
 * via __builtin_constant_p() allowing gcc to eliminate most of the
 * code, __usecs_to_jiffies() is called if the value passed does not
 * allow constant folding and the actual conversion must be done at
 * runtime.
 * the HZ range specific helpers _usecs_to_jiffies() are called both
 * directly here and from __msecs_to_jiffies() in the case where
 * constant folding is not possible.
 */
static __always_inline unsigned long usecs_to_jiffies(const unsigned int u)
{
	if (__builtin_constant_p(u)) {
		if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
			return MAX_JIFFY_OFFSET;
		return _usecs_to_jiffies(u);
	} else {
		return __usecs_to_jiffies(u);
	}
}

extern unsigned long timespec64_to_jiffies(const struct timespec64 *value);
extern void jiffies_to_timespec64(const unsigned long jiffies,
				  struct timespec64 *value);
static inline unsigned long timespec_to_jiffies(const struct timespec *value)
{
	struct timespec64 ts = timespec_to_timespec64(*value);

	return timespec64_to_jiffies(&ts);
}

static inline void jiffies_to_timespec(const unsigned long jiffies,
				       struct timespec *value)
{
	struct timespec64 ts;

	jiffies_to_timespec64(jiffies, &ts);
	*value = timespec64_to_timespec(ts);
}

extern unsigned long timeval_to_jiffies(const struct timeval *value);
extern void jiffies_to_timeval(const unsigned long jiffies,
			       struct timeval *value);

extern clock_t jiffies_to_clock_t(unsigned long x);
static inline clock_t jiffies_delta_to_clock_t(long delta)
{
	return jiffies_to_clock_t(max(0L, delta));
}

extern unsigned long clock_t_to_jiffies(unsigned long x);
extern u64 jiffies_64_to_clock_t(u64 x);
extern u64 nsec_to_clock_t(u64 x);
extern u64 nsecs_to_jiffies64(u64 n);
extern unsigned long nsecs_to_jiffies(u64 n);

#define TIMESTAMP_SIZE	30

#endif
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
1da177e4 LT	2	#ifndef _LINUX_JIFFIES_H
	3	#define _LINUX_JIFFIES_H
	4
7c30f352	5	#include <linux/cache.h>
f8bd2258	6	#include <linux/math64.h>
1da177e4 LT	7	#include <linux/kernel.h>
	8	#include <linux/types.h>
	9	#include <linux/time.h>
	10	#include <linux/timex.h>
	11	#include <asm/param.h> /* for HZ */
ca42aaf0	12	#include <generated/timeconst.h>
1da177e4 LT	13
	14	/*
	15	* The following defines establish the engineering parameters of the PLL
	16	* model. The HZ variable establishes the timer interrupt frequency, 100 Hz
	17	* for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the
	18	* OSF/1 kernel. The SHIFT_HZ define expresses the same value as the
	19	* nearest power of two in order to avoid hardware multiply operations.
	20	*/
	21	#if HZ >= 12 && HZ < 24
	22	# define SHIFT_HZ 4
	23	#elif HZ >= 24 && HZ < 48
	24	# define SHIFT_HZ 5
	25	#elif HZ >= 48 && HZ < 96
	26	# define SHIFT_HZ 6
	27	#elif HZ >= 96 && HZ < 192
	28	# define SHIFT_HZ 7
	29	#elif HZ >= 192 && HZ < 384
	30	# define SHIFT_HZ 8
	31	#elif HZ >= 384 && HZ < 768
	32	# define SHIFT_HZ 9
	33	#elif HZ >= 768 && HZ < 1536
	34	# define SHIFT_HZ 10
e118adef PM	35	#elif HZ >= 1536 && HZ < 3072
	36	# define SHIFT_HZ 11
	37	#elif HZ >= 3072 && HZ < 6144
	38	# define SHIFT_HZ 12
	39	#elif HZ >= 6144 && HZ < 12288
	40	# define SHIFT_HZ 13
1da177e4	41	#else
37679011	42	# error Invalid value of HZ.
1da177e4 LT	43	#endif
1da177e4 LT	44
25985edc	45	/* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can
1da177e4 LT	46	* improve accuracy by shifting LSH bits, hence calculating:
	47	* (NOM << LSH) / DEN
	48	* This however means trouble for large NOM, because (NOM << LSH) may no
	49	* longer fit in 32 bits. The following way of calculating this gives us
	50	* some slack, under the following conditions:
	51	* - (NOM / DEN) fits in (32 - LSH) bits.
	52	* - (NOM % DEN) fits in (32 - LSH) bits.
	53	*/
0d94df56 UZ	54	#define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \
0d94df56 UZ	55	+ ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN))
1da177e4	56
a7ea3bbf	57	/* LATCH is used in the interval timer and ftape setup. */
015a830d	58	#define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */
a7ea3bbf	59
b3c869d3	60	extern int register_refined_jiffies(long clock_tick_rate);
1da177e4	61
02ab20ae	62	/* TICK_NSEC is the time between ticks in nsec assuming SHIFTED_HZ */
b3c869d3	63	#define TICK_NSEC ((NSEC_PER_SEC+HZ/2)/HZ)
1da177e4	64
efefc977 RW	65	/* TICK_USEC is the time between ticks in usec assuming SHIFTED_HZ */
	66	#define TICK_USEC ((USEC_PER_SEC + HZ/2) / HZ)
	67
	68	/* USER_TICK_USEC is the time between ticks in usec assuming fake USER_HZ */
	69	#define USER_TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ)
1da177e4	70
60b0a8c3 MK	71	#ifndef __jiffy_arch_data
	72	#define __jiffy_arch_data
	73	#endif
	74
1da177e4	75	/*
98c4f0c3	76	* The 64-bit value is not atomic - you MUST NOT read it
d6ad4187	77	* without sampling the sequence number in jiffies_lock.
1da177e4 LT	78	* get_jiffies_64() will do this for you as appropriate.
1da177e4 LT	79	*/
7c30f352	80	extern u64 __cacheline_aligned_in_smp jiffies_64;
60b0a8c3	81	extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies;
1da177e4 LT	82
	83	#if (BITS_PER_LONG < 64)
	84	u64 get_jiffies_64(void);
	85	#else
	86	static inline u64 get_jiffies_64(void)
	87	{
	88	return (u64)jiffies;
	89	}
	90	#endif
	91
	92	/*
	93	* These inlines deal with timer wrapping correctly. You are
	94	* strongly encouraged to use them
	95	* 1. Because people otherwise forget
	96	* 2. Because if the timer wrap changes in future you won't have to
	97	* alter your driver code.
	98	*
	99	* time_after(a,b) returns true if the time a is after time b.
	100	*
	101	* Do this with "<0" and ">=0" to only test the sign of the result. A
	102	* good compiler would generate better code (and a really good compiler
	103	* wouldn't care). Gcc is currently neither.
	104	*/
	105	#define time_after(a,b) \
	106	(typecheck(unsigned long, a) && \
	107	typecheck(unsigned long, b) && \
5a581b36	108	((long)((b) - (a)) < 0))
1da177e4 LT	109	#define time_before(a,b) time_after(b,a)
	110
	111	#define time_after_eq(a,b) \
	112	(typecheck(unsigned long, a) && \
	113	typecheck(unsigned long, b) && \
5a581b36	114	((long)((a) - (b)) >= 0))
1da177e4 LT	115	#define time_before_eq(a,b) time_after_eq(b,a)
1da177e4 LT	116
64672d55 PS	117	/*
	118	* Calculate whether a is in the range of [b, c].
	119	*/
c7e15961 FOL	120	#define time_in_range(a,b,c) \
	121	(time_after_eq(a,b) && \
	122	time_before_eq(a,c))
	123
64672d55 PS	124	/*
	125	* Calculate whether a is in the range of [b, c).
	126	*/
	127	#define time_in_range_open(a,b,c) \
	128	(time_after_eq(a,b) && \
	129	time_before(a,c))
	130
3b171672 DZ	131	/* Same as above, but does so with platform independent 64bit types.
	132	* These must be used when utilizing jiffies_64 (i.e. return value of
	133	* get_jiffies_64() */
	134	#define time_after64(a,b) \
	135	(typecheck(__u64, a) && \
	136	typecheck(__u64, b) && \
5a581b36	137	((__s64)((b) - (a)) < 0))
3b171672 DZ	138	#define time_before64(a,b) time_after64(b,a)
	139
	140	#define time_after_eq64(a,b) \
	141	(typecheck(__u64, a) && \
	142	typecheck(__u64, b) && \
5a581b36	143	((__s64)((a) - (b)) >= 0))
3b171672 DZ	144	#define time_before_eq64(a,b) time_after_eq64(b,a)
3b171672 DZ	145
1bc2774d ET	146	#define time_in_range64(a, b, c) \
	147	(time_after_eq64(a, b) && \
	148	time_before_eq64(a, c))
	149
3f34d024 DY	150	/*
	151	* These four macros compare jiffies and 'a' for convenience.
	152	*/
	153
	154	/* time_is_before_jiffies(a) return true if a is before jiffies */
	155	#define time_is_before_jiffies(a) time_after(jiffies, a)
3740dcdf	156	#define time_is_before_jiffies64(a) time_after64(get_jiffies_64(), a)
3f34d024 DY	157
	158	/* time_is_after_jiffies(a) return true if a is after jiffies */
	159	#define time_is_after_jiffies(a) time_before(jiffies, a)
3740dcdf	160	#define time_is_after_jiffies64(a) time_before64(get_jiffies_64(), a)
3f34d024 DY	161
	162	/* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/
	163	#define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a)
3740dcdf	164	#define time_is_before_eq_jiffies64(a) time_after_eq64(get_jiffies_64(), a)
3f34d024 DY	165
	166	/* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/
	167	#define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a)
3740dcdf	168	#define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a)
3f34d024	169
1da177e4 LT	170	/*
	171	* Have the 32 bit jiffies value wrap 5 minutes after boot
	172	* so jiffies wrap bugs show up earlier.
	173	*/
	174	#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))
	175
	176	/*
	177	* Change timeval to jiffies, trying to avoid the
	178	* most obvious overflows..
	179	*
	180	* And some not so obvious.
	181	*
9f907c01	182	* Note that we don't want to return LONG_MAX, because
1da177e4 LT	183	* for various timeout reasons we often end up having
	184	* to wait "jiffies+1" in order to guarantee that we wait
	185	* at _least_ "jiffies" - so "jiffies+1" had better still
	186	* be positive.
	187	*/
9f907c01	188	#define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1)
1da177e4	189
bfe8df3d RD	190	extern unsigned long preset_lpj;
bfe8df3d RD	191
1da177e4 LT	192	/*
	193	* We want to do realistic conversions of time so we need to use the same
	194	* values the update wall clock code uses as the jiffies size. This value
	195	* is: TICK_NSEC (which is defined in timex.h). This
3eb05676	196	* is a constant and is in nanoseconds. We will use scaled math
1da177e4 LT	197	* with a set of scales defined here as SEC_JIFFIE_SC, USEC_JIFFIE_SC and
	198	* NSEC_JIFFIE_SC. Note that these defines contain nothing but
	199	* constants and so are computed at compile time. SHIFT_HZ (computed in
	200	* timex.h) adjusts the scaling for different HZ values.
	201
	202	* Scaled math??? What is that?
	203	*
	204	* Scaled math is a way to do integer math on values that would,
	205	* otherwise, either overflow, underflow, or cause undesired div
	206	* instructions to appear in the execution path. In short, we "scale"
	207	* up the operands so they take more bits (more precision, less
	208	* underflow), do the desired operation and then "scale" the result back
	209	* by the same amount. If we do the scaling by shifting we avoid the
	210	* costly mpy and the dastardly div instructions.
	211
	212	* Suppose, for example, we want to convert from seconds to jiffies
	213	* where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE. The
	214	* simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We
	215	* observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we
	216	* might calculate at compile time, however, the result will only have
	217	* about 3-4 bits of precision (less for smaller values of HZ).
	218	*
	219	* So, we scale as follows:
	220	* jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE);
	221	* jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE;
	222	* Then we make SCALE a power of two so:
	223	* jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE;
	224	* Now we define:
	225	* #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE))
	226	* jiff = (sec * SEC_CONV) >> SCALE;
	227	*
	228	* Often the math we use will expand beyond 32-bits so we tell C how to
	229	* do this and pass the 64-bit result of the mpy through the ">> SCALE"
	230	* which should take the result back to 32-bits. We want this expansion
	231	* to capture as much precision as possible. At the same time we don't
	232	* want to overflow so we pick the SCALE to avoid this. In this file,
	233	* that means using a different scale for each range of HZ values (as
	234	* defined in timex.h).
	235	*
	236	* For those who want to know, gcc will give a 64-bit result from a "*"
	237	* operator if the result is a long long AND at least one of the
	238	* operands is cast to long long (usually just prior to the "*" so as
	239	* not to confuse it into thinking it really has a 64-bit operand,
3eb05676	240	* which, buy the way, it can do, but it takes more code and at least 2
1da177e4 LT	241	* mpys).
	242
	243	* We also need to be aware that one second in nanoseconds is only a
	244	* couple of bits away from overflowing a 32-bit word, so we MUST use
	245	* 64-bits to get the full range time in nanoseconds.
	246
	247	*/
	248
	249	/*
	250	* Here are the scales we will use. One for seconds, nanoseconds and
	251	* microseconds.
	252	*
	253	* Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and
	254	* check if the sign bit is set. If not, we bump the shift count by 1.
	255	* (Gets an extra bit of precision where we can use it.)
	256	* We know it is set for HZ = 1024 and HZ = 100 not for 1000.
	257	* Haven't tested others.
	258
	259	* Limits of cpp (for #if expressions) only long (no long long), but
	260	* then we only need the most signicant bit.
	261	*/
	262
	263	#define SEC_JIFFIE_SC (31 - SHIFT_HZ)
	264	#if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000)
	265	#undef SEC_JIFFIE_SC
	266	#define SEC_JIFFIE_SC (32 - SHIFT_HZ)
	267	#endif
	268	#define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29)
1da177e4 LT	269	#define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\
	270	TICK_NSEC -1) / (u64)TICK_NSEC))
	271
	272	#define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\
	273	TICK_NSEC -1) / (u64)TICK_NSEC))
1da177e4 LT	274	/*
	275	* The maximum jiffie value is (MAX_INT >> 1). Here we translate that
	276	* into seconds. The 64-bit case will overflow if we are not careful,
	277	* so use the messy SH_DIV macro to do it. Still all constants.
	278	*/
	279	#if BITS_PER_LONG < 64
	280	# define MAX_SEC_IN_JIFFIES \
	281	(long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC)
	282	#else /* take care of overflow on 64 bits machines */
	283	# define MAX_SEC_IN_JIFFIES \
	284	(SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1)
	285
	286	#endif
	287
	288	/*
8b9365d7	289	* Convert various time units to each other:
1da177e4	290	*/
8b9365d7 IM	291	extern unsigned int jiffies_to_msecs(const unsigned long j);
8b9365d7 IM	292	extern unsigned int jiffies_to_usecs(const unsigned long j);
8fe8ff09 KH	293
	294	static inline u64 jiffies_to_nsecs(const unsigned long j)
	295	{
	296	return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC;
	297	}
	298
07e5f5e3 FW	299	extern u64 jiffies64_to_nsecs(u64 j);
07e5f5e3 FW	300
ca42aaf0 NMG	301	extern unsigned long __msecs_to_jiffies(const unsigned int m);
	302	#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
	303	/*
	304	* HZ is equal to or smaller than 1000, and 1000 is a nice round
	305	* multiple of HZ, divide with the factor between them, but round
	306	* upwards:
	307	*/
	308	static inline unsigned long _msecs_to_jiffies(const unsigned int m)
	309	{
4e3d9cb0	310	return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
ca42aaf0 NMG	311	}
	312	#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
	313	/*
	314	* HZ is larger than 1000, and HZ is a nice round multiple of 1000 -
	315	* simply multiply with the factor between them.
	316	*
	317	* But first make sure the multiplication result cannot overflow:
	318	*/
	319	static inline unsigned long _msecs_to_jiffies(const unsigned int m)
	320	{
4e3d9cb0 TG	321	if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
	322	return MAX_JIFFY_OFFSET;
	323	return m * (HZ / MSEC_PER_SEC);
ca42aaf0 NMG	324	}
	325	#else
	326	/*
	327	* Generic case - multiply, round and divide. But first check that if
	328	* we are doing a net multiplication, that we wouldn't overflow:
	329	*/
	330	static inline unsigned long _msecs_to_jiffies(const unsigned int m)
	331	{
4e3d9cb0 TG	332	if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
4e3d9cb0 TG	333	return MAX_JIFFY_OFFSET;
ca42aaf0	334
4e3d9cb0	335	return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32) >> MSEC_TO_HZ_SHR32;
ca42aaf0 NMG	336	}
	337	#endif
	338	/**
	339	* msecs_to_jiffies: - convert milliseconds to jiffies
	340	* @m: time in milliseconds
	341	*
	342	* conversion is done as follows:
	343	*
	344	* - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
	345	*
	346	* - 'too large' values [that would result in larger than
	347	* MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
	348	*
	349	* - all other values are converted to jiffies by either multiplying
	350	* the input value by a factor or dividing it with a factor and
	351	* handling any 32-bit overflows.
	352	* for the details see __msecs_to_jiffies()
	353	*
daa67b4b NMG	354	* msecs_to_jiffies() checks for the passed in value being a constant
	355	* via __builtin_constant_p() allowing gcc to eliminate most of the
	356	* code, __msecs_to_jiffies() is called if the value passed does not
	357	* allow constant folding and the actual conversion must be done at
	358	* runtime.
	359	* the HZ range specific helpers _msecs_to_jiffies() are called both
	360	* directly here and from __msecs_to_jiffies() in the case where
	361	* constant folding is not possible.
ca42aaf0	362	*/
accd0b9e	363	static __always_inline unsigned long msecs_to_jiffies(const unsigned int m)
ca42aaf0	364	{
daa67b4b NMG	365	if (__builtin_constant_p(m)) {
	366	if ((int)m < 0)
	367	return MAX_JIFFY_OFFSET;
	368	return _msecs_to_jiffies(m);
	369	} else {
	370	return __msecs_to_jiffies(m);
	371	}
ca42aaf0 NMG	372	}
ca42aaf0 NMG	373
ae60d6a0	374	extern unsigned long __usecs_to_jiffies(const unsigned int u);
e0758676	375	#if !(USEC_PER_SEC % HZ)
ae60d6a0 NMG	376	static inline unsigned long _usecs_to_jiffies(const unsigned int u)
	377	{
	378	return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
	379	}
ae60d6a0 NMG	380	#else
	381	static inline unsigned long _usecs_to_jiffies(const unsigned int u)
	382	{
	383	return (USEC_TO_HZ_MUL32 * u + USEC_TO_HZ_ADJ32)
	384	>> USEC_TO_HZ_SHR32;
	385	}
	386	#endif
	387
c569a23d NMG	388	/**
	389	* usecs_to_jiffies: - convert microseconds to jiffies
	390	* @u: time in microseconds
	391	*
	392	* conversion is done as follows:
	393	*
	394	* - 'too large' values [that would result in larger than
	395	* MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
	396	*
	397	* - all other values are converted to jiffies by either multiplying
	398	* the input value by a factor or dividing it with a factor and
	399	* handling any 32-bit overflows as for msecs_to_jiffies.
	400	*
	401	* usecs_to_jiffies() checks for the passed in value being a constant
	402	* via __builtin_constant_p() allowing gcc to eliminate most of the
	403	* code, __usecs_to_jiffies() is called if the value passed does not
	404	* allow constant folding and the actual conversion must be done at
	405	* runtime.
	406	* the HZ range specific helpers _usecs_to_jiffies() are called both
	407	* directly here and from __msecs_to_jiffies() in the case where
	408	* constant folding is not possible.
	409	*/
accd0b9e	410	static __always_inline unsigned long usecs_to_jiffies(const unsigned int u)
ae60d6a0	411	{
c569a23d NMG	412	if (__builtin_constant_p(u)) {
	413	if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
	414	return MAX_JIFFY_OFFSET;
	415	return _usecs_to_jiffies(u);
	416	} else {
	417	return __usecs_to_jiffies(u);
	418	}
ae60d6a0 NMG	419	}
ae60d6a0 NMG	420
9ca30850 BW	421	extern unsigned long timespec64_to_jiffies(const struct timespec64 *value);
	422	extern void jiffies_to_timespec64(const unsigned long jiffies,
	423	struct timespec64 *value);
	424	static inline unsigned long timespec_to_jiffies(const struct timespec *value)
	425	{
	426	struct timespec64 ts = timespec_to_timespec64(*value);
	427
	428	return timespec64_to_jiffies(&ts);
	429	}
	430
	431	static inline void jiffies_to_timespec(const unsigned long jiffies,
	432	struct timespec *value)
	433	{
	434	struct timespec64 ts;
	435
	436	jiffies_to_timespec64(jiffies, &ts);
	437	*value = timespec64_to_timespec(ts);
	438	}
	439
8b9365d7 IM	440	extern unsigned long timeval_to_jiffies(const struct timeval *value);
	441	extern void jiffies_to_timeval(const unsigned long jiffies,
	442	struct timeval *value);
a399a805	443
cbbc719f	444	extern clock_t jiffies_to_clock_t(unsigned long x);
a399a805 ED	445	static inline clock_t jiffies_delta_to_clock_t(long delta)
	446	{
	447	return jiffies_to_clock_t(max(0L, delta));
	448	}
	449
8b9365d7 IM	450	extern unsigned long clock_t_to_jiffies(unsigned long x);
	451	extern u64 jiffies_64_to_clock_t(u64 x);
	452	extern u64 nsec_to_clock_t(u64 x);
a1dabb6b	453	extern u64 nsecs_to_jiffies64(u64 n);
b7b20df9	454	extern unsigned long nsecs_to_jiffies(u64 n);
8b9365d7 IM	455
8b9365d7 IM	456	#define TIMESTAMP_SIZE 30
1da177e4 LT	457
1da177e4 LT	458	#endif