2 * include/linux/ktime.h
4 * ktime_t - nanosecond-resolution time format.
6 * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
7 * Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
9 * data type definitions, declarations, prototypes and macros.
11 * Started by: Thomas Gleixner and Ingo Molnar
15 * Roman Zippel provided the ideas and primary code snippets of
16 * the ktime_t union and further simplifications of the original
19 * For licencing details see kernel-base/COPYING
21 #ifndef _LINUX_KTIME_H
22 #define _LINUX_KTIME_H
24 #include <linux/time.h>
25 #include <linux/jiffies.h>
30 * On 64-bit CPUs a single 64-bit variable is used to store the hrtimers
31 * internal representation of time values in scalar nanoseconds. The
32 * design plays out best on 64-bit CPUs, where most conversions are
33 * NOPs and most arithmetic ktime_t operations are plain arithmetic
36 * On 32-bit CPUs an optimized representation of the timespec structure
37 * is used to avoid expensive conversions from and to timespecs. The
38 * endian-aware order of the tv struct members is choosen to allow
39 * mathematical operations on the tv64 member of the union too, which
40 * for certain operations produces better code.
42 * For architectures with efficient support for 64/32-bit conversions the
43 * plain scalar nanosecond based representation can be selected by the
44 * config switch CONFIG_KTIME_SCALAR.
48 #if BITS_PER_LONG != 64 && !defined(CONFIG_KTIME_SCALAR)
59 typedef union ktime ktime_t
; /* Kill this */
61 #define KTIME_MAX ((s64)~((u64)1 << 63))
62 #if (BITS_PER_LONG == 64)
63 # define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC)
65 # define KTIME_SEC_MAX LONG_MAX
69 * ktime_t definitions when using the 64-bit scalar representation:
72 #if (BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)
75 * ktime_set - Set a ktime_t variable from a seconds/nanoseconds value
76 * @secs: seconds to set
77 * @nsecs: nanoseconds to set
79 * Return the ktime_t representation of the value
81 static inline ktime_t
ktime_set(const long secs
, const unsigned long nsecs
)
83 #if (BITS_PER_LONG == 64)
84 if (unlikely(secs
>= KTIME_SEC_MAX
))
85 return (ktime_t
){ .tv64
= KTIME_MAX
};
87 return (ktime_t
) { .tv64
= (s64
)secs
* NSEC_PER_SEC
+ (s64
)nsecs
};
90 /* Subtract two ktime_t variables. rem = lhs -rhs: */
91 #define ktime_sub(lhs, rhs) \
92 ({ (ktime_t){ .tv64 = (lhs).tv64 - (rhs).tv64 }; })
94 /* Add two ktime_t variables. res = lhs + rhs: */
95 #define ktime_add(lhs, rhs) \
96 ({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; })
99 * Add a ktime_t variable and a scalar nanosecond value.
102 #define ktime_add_ns(kt, nsval) \
103 ({ (ktime_t){ .tv64 = (kt).tv64 + (nsval) }; })
106 * Subtract a scalar nanosecod from a ktime_t variable
109 #define ktime_sub_ns(kt, nsval) \
110 ({ (ktime_t){ .tv64 = (kt).tv64 - (nsval) }; })
112 /* convert a timespec to ktime_t format: */
113 static inline ktime_t
timespec_to_ktime(struct timespec ts
)
115 return ktime_set(ts
.tv_sec
, ts
.tv_nsec
);
118 /* convert a timeval to ktime_t format: */
119 static inline ktime_t
timeval_to_ktime(struct timeval tv
)
121 return ktime_set(tv
.tv_sec
, tv
.tv_usec
* NSEC_PER_USEC
);
124 /* Map the ktime_t to timespec conversion to ns_to_timespec function */
125 #define ktime_to_timespec(kt) ns_to_timespec((kt).tv64)
127 /* Map the ktime_t to timeval conversion to ns_to_timeval function */
128 #define ktime_to_timeval(kt) ns_to_timeval((kt).tv64)
130 /* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
131 #define ktime_to_ns(kt) ((kt).tv64)
136 * Helper macros/inlines to get the ktime_t math right in the timespec
137 * representation. The macros are sometimes ugly - their actual use is
138 * pretty okay-ish, given the circumstances. We do all this for
139 * performance reasons. The pure scalar nsec_t based code was nice and
140 * simple, but created too many 64-bit / 32-bit conversions and divisions.
142 * Be especially aware that negative values are represented in a way
143 * that the tv.sec field is negative and the tv.nsec field is greater
144 * or equal to zero but less than nanoseconds per second. This is the
145 * same representation which is used by timespecs.
147 * tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC
150 /* Set a ktime_t variable to a value in sec/nsec representation: */
151 static inline ktime_t
ktime_set(const long secs
, const unsigned long nsecs
)
153 return (ktime_t
) { .tv
= { .sec
= secs
, .nsec
= nsecs
} };
157 * ktime_sub - subtract two ktime_t variables
161 * Returns the remainder of the substraction
163 static inline ktime_t
ktime_sub(const ktime_t lhs
, const ktime_t rhs
)
167 res
.tv64
= lhs
.tv64
- rhs
.tv64
;
169 res
.tv
.nsec
+= NSEC_PER_SEC
;
175 * ktime_add - add two ktime_t variables
179 * Returns the sum of @add1 and @add2.
181 static inline ktime_t
ktime_add(const ktime_t add1
, const ktime_t add2
)
185 res
.tv64
= add1
.tv64
+ add2
.tv64
;
187 * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx
188 * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit.
190 * it's equivalent to:
191 * tv.nsec -= NSEC_PER_SEC
194 if (res
.tv
.nsec
>= NSEC_PER_SEC
)
195 res
.tv64
+= (u32
)-NSEC_PER_SEC
;
201 * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
203 * @nsec: the scalar nsec value to add
205 * Returns the sum of @kt and @nsec in ktime_t format
207 extern ktime_t
ktime_add_ns(const ktime_t kt
, u64 nsec
);
210 * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
212 * @nsec: the scalar nsec value to subtract
214 * Returns the subtraction of @nsec from @kt in ktime_t format
216 extern ktime_t
ktime_sub_ns(const ktime_t kt
, u64 nsec
);
219 * timespec_to_ktime - convert a timespec to ktime_t format
220 * @ts: the timespec variable to convert
222 * Returns a ktime_t variable with the converted timespec value
224 static inline ktime_t
timespec_to_ktime(const struct timespec ts
)
226 return (ktime_t
) { .tv
= { .sec
= (s32
)ts
.tv_sec
,
227 .nsec
= (s32
)ts
.tv_nsec
} };
231 * timeval_to_ktime - convert a timeval to ktime_t format
232 * @tv: the timeval variable to convert
234 * Returns a ktime_t variable with the converted timeval value
236 static inline ktime_t
timeval_to_ktime(const struct timeval tv
)
238 return (ktime_t
) { .tv
= { .sec
= (s32
)tv
.tv_sec
,
239 .nsec
= (s32
)tv
.tv_usec
* 1000 } };
243 * ktime_to_timespec - convert a ktime_t variable to timespec format
244 * @kt: the ktime_t variable to convert
246 * Returns the timespec representation of the ktime value
248 static inline struct timespec
ktime_to_timespec(const ktime_t kt
)
250 return (struct timespec
) { .tv_sec
= (time_t) kt
.tv
.sec
,
251 .tv_nsec
= (long) kt
.tv
.nsec
};
255 * ktime_to_timeval - convert a ktime_t variable to timeval format
256 * @kt: the ktime_t variable to convert
258 * Returns the timeval representation of the ktime value
260 static inline struct timeval
ktime_to_timeval(const ktime_t kt
)
262 return (struct timeval
) {
263 .tv_sec
= (time_t) kt
.tv
.sec
,
264 .tv_usec
= (suseconds_t
) (kt
.tv
.nsec
/ NSEC_PER_USEC
) };
268 * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds
269 * @kt: the ktime_t variable to convert
271 * Returns the scalar nanoseconds representation of @kt
273 static inline s64
ktime_to_ns(const ktime_t kt
)
275 return (s64
) kt
.tv
.sec
* NSEC_PER_SEC
+ kt
.tv
.nsec
;
281 * ktime_equal - Compares two ktime_t variables to see if they are equal
285 * Compare two ktime_t variables, returns 1 if equal
287 static inline int ktime_equal(const ktime_t cmp1
, const ktime_t cmp2
)
289 return cmp1
.tv64
== cmp2
.tv64
;
292 static inline s64
ktime_to_us(const ktime_t kt
)
294 struct timeval tv
= ktime_to_timeval(kt
);
295 return (s64
) tv
.tv_sec
* USEC_PER_SEC
+ tv
.tv_usec
;
298 static inline s64
ktime_us_delta(const ktime_t later
, const ktime_t earlier
)
300 return ktime_to_us(ktime_sub(later
, earlier
));
303 static inline ktime_t
ktime_add_us(const ktime_t kt
, const u64 usec
)
305 return ktime_add_ns(kt
, usec
* 1000);
308 static inline ktime_t
ktime_sub_us(const ktime_t kt
, const u64 usec
)
310 return ktime_sub_ns(kt
, usec
* 1000);
313 extern ktime_t
ktime_add_safe(const ktime_t lhs
, const ktime_t rhs
);
316 * The resolution of the clocks. The resolution value is returned in
317 * the clock_getres() system call to give application programmers an
318 * idea of the (in)accuracy of timers. Timer values are rounded up to
319 * this resolution values.
321 #define LOW_RES_NSEC TICK_NSEC
322 #define KTIME_LOW_RES (ktime_t){ .tv64 = LOW_RES_NSEC }
324 /* Get the monotonic time in timespec format: */
325 extern void ktime_get_ts(struct timespec
*ts
);
327 /* Get the real (wall-) time in timespec format: */
328 #define ktime_get_real_ts(ts) getnstimeofday(ts)
330 static inline ktime_t
ns_to_ktime(u64 ns
)
332 static const ktime_t ktime_zero
= { .tv64
= 0 };
333 return ktime_add_ns(ktime_zero
, ns
);
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