ktime.h revision 282513 
1/*-
2 * Copyright (c) 2014 Mellanox Technologies, Ltd.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice unmodified, this list of conditions, and the following
10 *    disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#ifndef _LINUX_KTIME_H
28#define _LINUX_KTIME_H
29
30#include <sys/time.h>
31#include <linux/types.h>
32#include <linux/jiffies.h>
33
34
35/* Get the monotonic time in timespec format: */
36#define ktime_get_ts getnanouptime
37
38#define NSEC_PER_USEC   1000L
39#define NSEC_PER_SEC    1000000000L
40
41/*
42 * ktime_t:
43 *
44 * On 64-bit CPUs a single 64-bit variable is used to store the hrtimers
45 * internal representation of time values in scalar nanoseconds. The
46 * design plays out best on 64-bit CPUs, where most conversions are
47 * NOPs and most arithmetic ktime_t operations are plain arithmetic
48 * operations.
49 *
50 * On 32-bit CPUs an optimized representation of the timespec structure
51 * is used to avoid expensive conversions from and to timespecs. The
52 * endian-aware order of the tv struct members is chosen to allow
53 * mathematical operations on the tv64 member of the union too, which
54 * for certain operations produces better code.
55 *
56 * For architectures with efficient support for 64/32-bit conversions the
57 * plain scalar nanosecond based representation can be selected by the
58 * config switch CONFIG_KTIME_SCALAR.
59 */
60union ktime {
61	s64	tv64;
62#if BITS_PER_LONG != 64 && !defined(CONFIG_KTIME_SCALAR)
63	struct {
64# ifdef __BIG_ENDIAN
65	s32	sec, nsec;
66# else
67	s32	nsec, sec;
68# endif
69	} tv;
70#endif
71};
72
73typedef union ktime ktime_t;		/* Kill this */
74
75#define KTIME_MAX                       ((s64)~((u64)1 << 63))
76#define KTIME_SEC_MAX                   (KTIME_MAX / NSEC_PER_SEC)
77
78/*
79 * ktime_t definitions when using the 64-bit scalar representation:
80 */
81
82#if (BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)
83
84/**
85 * ktime_set - Set a ktime_t variable from a seconds/nanoseconds value
86 * @secs:	seconds to set
87 * @nsecs:	nanoseconds to set
88 *
89 * Return the ktime_t representation of the value
90 */
91static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
92{
93#if (BITS_PER_LONG == 64)
94	if (unlikely(secs >= KTIME_SEC_MAX))
95		return (ktime_t){ .tv64 = KTIME_MAX };
96#endif
97	return (ktime_t) { .tv64 = (s64)secs * NSEC_PER_SEC + (s64)nsecs };
98}
99
100/* Subtract two ktime_t variables. rem = lhs -rhs: */
101#define ktime_sub(lhs, rhs) \
102		({ (ktime_t){ .tv64 = (lhs).tv64 - (rhs).tv64 }; })
103
104/* Add two ktime_t variables. res = lhs + rhs: */
105#define ktime_add(lhs, rhs) \
106		({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; })
107
108/*
109 * Add a ktime_t variable and a scalar nanosecond value.
110 * res = kt + nsval:
111 */
112#define ktime_add_ns(kt, nsval) \
113		({ (ktime_t){ .tv64 = (kt).tv64 + (nsval) }; })
114
115/*
116 * Subtract a scalar nanosecod from a ktime_t variable
117 * res = kt - nsval:
118 */
119#define ktime_sub_ns(kt, nsval) \
120		({ (ktime_t){ .tv64 = (kt).tv64 - (nsval) }; })
121
122/* convert a timespec to ktime_t format: */
123static inline ktime_t timespec_to_ktime(struct timespec ts)
124{
125	return ktime_set(ts.tv_sec, ts.tv_nsec);
126}
127
128/* convert a timeval to ktime_t format: */
129static inline ktime_t timeval_to_ktime(struct timeval tv)
130{
131	return ktime_set(tv.tv_sec, tv.tv_usec * NSEC_PER_USEC);
132}
133
134/* Map the ktime_t to timespec conversion to ns_to_timespec function */
135#define ktime_to_timespec(kt)		ns_to_timespec((kt).tv64)
136
137/* Map the ktime_t to timeval conversion to ns_to_timeval function */
138#define ktime_to_timeval(kt)		ns_to_timeval((kt).tv64)
139
140/* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
141#define ktime_to_ns(kt)			((kt).tv64)
142
143#else	/* !((BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)) */
144
145/*
146 * Helper macros/inlines to get the ktime_t math right in the timespec
147 * representation. The macros are sometimes ugly - their actual use is
148 * pretty okay-ish, given the circumstances. We do all this for
149 * performance reasons. The pure scalar nsec_t based code was nice and
150 * simple, but created too many 64-bit / 32-bit conversions and divisions.
151 *
152 * Be especially aware that negative values are represented in a way
153 * that the tv.sec field is negative and the tv.nsec field is greater
154 * or equal to zero but less than nanoseconds per second. This is the
155 * same representation which is used by timespecs.
156 *
157 *   tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC
158 */
159
160/* Set a ktime_t variable to a value in sec/nsec representation: */
161static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
162{
163	return (ktime_t) { .tv = { .sec = secs, .nsec = nsecs } };
164}
165
166/**
167 * ktime_sub - subtract two ktime_t variables
168 * @lhs:	minuend
169 * @rhs:	subtrahend
170 *
171 * Returns the remainder of the subtraction
172 */
173static inline ktime_t ktime_sub(const ktime_t lhs, const ktime_t rhs)
174{
175	ktime_t res;
176
177	res.tv64 = lhs.tv64 - rhs.tv64;
178	if (res.tv.nsec < 0)
179		res.tv.nsec += NSEC_PER_SEC;
180
181	return res;
182}
183
184/**
185 * ktime_add - add two ktime_t variables
186 * @add1:	addend1
187 * @add2:	addend2
188 *
189 * Returns the sum of @add1 and @add2.
190 */
191static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2)
192{
193	ktime_t res;
194
195	res.tv64 = add1.tv64 + add2.tv64;
196	/*
197	 * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx
198	 * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit.
199	 *
200	 * it's equivalent to:
201	 *   tv.nsec -= NSEC_PER_SEC
202	 *   tv.sec ++;
203	 */
204	if (res.tv.nsec >= NSEC_PER_SEC)
205		res.tv64 += (u32)-NSEC_PER_SEC;
206
207	return res;
208}
209
210/**
211 * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
212 * @kt:		addend
213 * @nsec:	the scalar nsec value to add
214 *
215 * Returns the sum of @kt and @nsec in ktime_t format
216 */
217extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec);
218
219/**
220 * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
221 * @kt:		minuend
222 * @nsec:	the scalar nsec value to subtract
223 *
224 * Returns the subtraction of @nsec from @kt in ktime_t format
225 */
226extern ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec);
227
228/**
229 * timespec_to_ktime - convert a timespec to ktime_t format
230 * @ts:		the timespec variable to convert
231 *
232 * Returns a ktime_t variable with the converted timespec value
233 */
234static inline ktime_t timespec_to_ktime(const struct timespec ts)
235{
236	return (ktime_t) { .tv = { .sec = (s32)ts.tv_sec,
237			   	   .nsec = (s32)ts.tv_nsec } };
238}
239
240/**
241 * timeval_to_ktime - convert a timeval to ktime_t format
242 * @tv:		the timeval variable to convert
243 *
244 * Returns a ktime_t variable with the converted timeval value
245 */
246static inline ktime_t timeval_to_ktime(const struct timeval tv)
247{
248	return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec,
249				   .nsec = (s32)(tv.tv_usec *
250						 NSEC_PER_USEC) } };
251}
252
253/**
254 * ktime_to_timespec - convert a ktime_t variable to timespec format
255 * @kt:		the ktime_t variable to convert
256 *
257 * Returns the timespec representation of the ktime value
258 */
259static inline struct timespec ktime_to_timespec(const ktime_t kt)
260{
261	return (struct timespec) { .tv_sec = (time_t) kt.tv.sec,
262				   .tv_nsec = (long) kt.tv.nsec };
263}
264
265/**
266 * ktime_to_timeval - convert a ktime_t variable to timeval format
267 * @kt:		the ktime_t variable to convert
268 *
269 * Returns the timeval representation of the ktime value
270 */
271static inline struct timeval ktime_to_timeval(const ktime_t kt)
272{
273	return (struct timeval) {
274		.tv_sec = (time_t) kt.tv.sec,
275		.tv_usec = (suseconds_t) (kt.tv.nsec / NSEC_PER_USEC) };
276}
277
278/**
279 * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds
280 * @kt:		the ktime_t variable to convert
281 *
282 * Returns the scalar nanoseconds representation of @kt
283 */
284static inline s64 ktime_to_ns(const ktime_t kt)
285{
286	return (s64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec;
287}
288
289#endif	/* !((BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)) */
290
291static inline s64 ktime_get_ns(void)
292{
293	struct timespec ts;
294	ktime_t kt;
295	ktime_get_ts(&ts);
296	kt = timespec_to_ktime(ts);
297	return (ktime_to_ns(kt));
298}
299
300#endif	/* _LINUX_KTIME_H */
301