Line data Source code
1 : /*
2 : * include/linux/ktime.h
3 : *
4 : * ktime_t - nanosecond-resolution time format.
5 : *
6 : * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
7 : * Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
8 : *
9 : * data type definitions, declarations, prototypes and macros.
10 : *
11 : * Started by: Thomas Gleixner and Ingo Molnar
12 : *
13 : * Credits:
14 : *
15 : * Roman Zippel provided the ideas and primary code snippets of
16 : * the ktime_t union and further simplifications of the original
17 : * code.
18 : *
19 : * For licencing details see kernel-base/COPYING
20 : */
21 : #ifndef _LINUX_KTIME_H
22 : #define _LINUX_KTIME_H
23 :
24 : #include <linux/time.h>
25 : #include <linux/jiffies.h>
26 :
27 : /*
28 : * ktime_t:
29 : *
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
34 : * operations.
35 : *
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.
41 : *
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.
45 : */
46 : union ktime {
47 : s64 tv64;
48 : #if BITS_PER_LONG != 64 && !defined(CONFIG_KTIME_SCALAR)
49 : struct {
50 : # ifdef __BIG_ENDIAN
51 : s32 sec, nsec;
52 : # else
53 : s32 nsec, sec;
54 : # endif
55 : } tv;
56 : #endif
57 : };
58 :
59 1 : typedef union ktime ktime_t; /* Kill this */
60 :
61 : #define KTIME_MAX ((s64)~((u64)1 << 63))
62 : #if (BITS_PER_LONG == 64)
63 : # define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC)
64 : #else
65 : # define KTIME_SEC_MAX LONG_MAX
66 : #endif
67 :
68 : /*
69 : * ktime_t definitions when using the 64-bit scalar representation:
70 : */
71 :
72 : #if (BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)
73 :
74 : /**
75 : * ktime_set - Set a ktime_t variable from a seconds/nanoseconds value
76 : * @secs: seconds to set
77 : * @nsecs: nanoseconds to set
78 : *
79 : * Return the ktime_t representation of the value
80 : */
81 : static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
82 : {
83 : #if (BITS_PER_LONG == 64)
84 : if (unlikely(secs >= KTIME_SEC_MAX))
85 : return (ktime_t){ .tv64 = KTIME_MAX };
86 : #endif
87 : return (ktime_t) { .tv64 = (s64)secs * NSEC_PER_SEC + (s64)nsecs };
88 : }
89 :
90 : /* Subtract two ktime_t variables. rem = lhs -rhs: */
91 : #define ktime_sub(lhs, rhs) \
92 : ({ (ktime_t){ .tv64 = (lhs).tv64 - (rhs).tv64 }; })
93 :
94 : /* Add two ktime_t variables. res = lhs + rhs: */
95 : #define ktime_add(lhs, rhs) \
96 : ({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; })
97 :
98 : /*
99 : * Add a ktime_t variable and a scalar nanosecond value.
100 : * res = kt + nsval:
101 : */
102 : #define ktime_add_ns(kt, nsval) \
103 : ({ (ktime_t){ .tv64 = (kt).tv64 + (nsval) }; })
104 :
105 : /*
106 : * Subtract a scalar nanosecod from a ktime_t variable
107 : * res = kt - nsval:
108 : */
109 : #define ktime_sub_ns(kt, nsval) \
110 : ({ (ktime_t){ .tv64 = (kt).tv64 - (nsval) }; })
111 :
112 : /* convert a timespec to ktime_t format: */
113 : static inline ktime_t timespec_to_ktime(struct timespec ts)
114 : {
115 : return ktime_set(ts.tv_sec, ts.tv_nsec);
116 : }
117 :
118 : /* convert a timeval to ktime_t format: */
119 : static inline ktime_t timeval_to_ktime(struct timeval tv)
120 : {
121 : return ktime_set(tv.tv_sec, tv.tv_usec * NSEC_PER_USEC);
122 : }
123 :
124 : /* Map the ktime_t to timespec conversion to ns_to_timespec function */
125 : #define ktime_to_timespec(kt) ns_to_timespec((kt).tv64)
126 :
127 : /* Map the ktime_t to timeval conversion to ns_to_timeval function */
128 : #define ktime_to_timeval(kt) ns_to_timeval((kt).tv64)
129 :
130 : /* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
131 : #define ktime_to_ns(kt) ((kt).tv64)
132 :
133 : #else
134 :
135 : /*
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.
141 : *
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.
146 : *
147 : * tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC
148 : */
149 :
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)
152 : {
153 : return (ktime_t) { .tv = { .sec = secs, .nsec = nsecs } };
154 : }
155 :
156 : /**
157 : * ktime_sub - subtract two ktime_t variables
158 : * @lhs: minuend
159 : * @rhs: subtrahend
160 : *
161 : * Returns the remainder of the substraction
162 : */
163 : static inline ktime_t ktime_sub(const ktime_t lhs, const ktime_t rhs)
164 : {
165 : ktime_t res;
166 :
167 : res.tv64 = lhs.tv64 - rhs.tv64;
168 : if (res.tv.nsec < 0)
169 : res.tv.nsec += NSEC_PER_SEC;
170 :
171 : return res;
172 : }
173 :
174 : /**
175 : * ktime_add - add two ktime_t variables
176 : * @add1: addend1
177 : * @add2: addend2
178 : *
179 : * Returns the sum of @add1 and @add2.
180 : */
181 : static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2)
182 : {
183 : ktime_t res;
184 :
185 : res.tv64 = add1.tv64 + add2.tv64;
186 : /*
187 : * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx
188 : * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit.
189 : *
190 : * it's equivalent to:
191 : * tv.nsec -= NSEC_PER_SEC
192 : * tv.sec ++;
193 : */
194 : if (res.tv.nsec >= NSEC_PER_SEC)
195 : res.tv64 += (u32)-NSEC_PER_SEC;
196 :
197 : return res;
198 : }
199 :
200 : /**
201 : * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
202 : * @kt: addend
203 : * @nsec: the scalar nsec value to add
204 : *
205 : * Returns the sum of @kt and @nsec in ktime_t format
206 : */
207 : extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec);
208 :
209 : /**
210 : * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
211 : * @kt: minuend
212 : * @nsec: the scalar nsec value to subtract
213 : *
214 : * Returns the subtraction of @nsec from @kt in ktime_t format
215 : */
216 : extern ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec);
217 :
218 : /**
219 : * timespec_to_ktime - convert a timespec to ktime_t format
220 : * @ts: the timespec variable to convert
221 : *
222 : * Returns a ktime_t variable with the converted timespec value
223 : */
224 : static inline ktime_t timespec_to_ktime(const struct timespec ts)
225 : {
226 : return (ktime_t) { .tv = { .sec = (s32)ts.tv_sec,
227 : .nsec = (s32)ts.tv_nsec } };
228 : }
229 :
230 : /**
231 : * timeval_to_ktime - convert a timeval to ktime_t format
232 : * @tv: the timeval variable to convert
233 : *
234 : * Returns a ktime_t variable with the converted timeval value
235 : */
236 : static inline ktime_t timeval_to_ktime(const struct timeval tv)
237 : {
238 : return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec,
239 : .nsec = (s32)tv.tv_usec * 1000 } };
240 : }
241 :
242 : /**
243 : * ktime_to_timespec - convert a ktime_t variable to timespec format
244 : * @kt: the ktime_t variable to convert
245 : *
246 : * Returns the timespec representation of the ktime value
247 : */
248 : static inline struct timespec ktime_to_timespec(const ktime_t kt)
249 : {
250 : return (struct timespec) { .tv_sec = (time_t) kt.tv.sec,
251 : .tv_nsec = (long) kt.tv.nsec };
252 : }
253 :
254 : /**
255 : * ktime_to_timeval - convert a ktime_t variable to timeval format
256 : * @kt: the ktime_t variable to convert
257 : *
258 : * Returns the timeval representation of the ktime value
259 : */
260 : static inline struct timeval ktime_to_timeval(const ktime_t kt)
261 : {
262 : return (struct timeval) {
263 : .tv_sec = (time_t) kt.tv.sec,
264 : .tv_usec = (suseconds_t) (kt.tv.nsec / NSEC_PER_USEC) };
265 : }
266 :
267 : /**
268 : * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds
269 : * @kt: the ktime_t variable to convert
270 : *
271 : * Returns the scalar nanoseconds representation of @kt
272 : */
273 : static inline s64 ktime_to_ns(const ktime_t kt)
274 : {
275 : return (s64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec;
276 : }
277 :
278 : #endif
279 :
280 : /**
281 : * ktime_equal - Compares two ktime_t variables to see if they are equal
282 : * @cmp1: comparable1
283 : * @cmp2: comparable2
284 : *
285 : * Compare two ktime_t variables, returns 1 if equal
286 : */
287 : static inline int ktime_equal(const ktime_t cmp1, const ktime_t cmp2)
288 : {
289 : return cmp1.tv64 == cmp2.tv64;
290 : }
291 :
292 : static inline s64 ktime_to_us(const ktime_t kt)
293 : {
294 : struct timeval tv = ktime_to_timeval(kt);
295 : return (s64) tv.tv_sec * USEC_PER_SEC + tv.tv_usec;
296 : }
297 :
298 : static inline s64 ktime_us_delta(const ktime_t later, const ktime_t earlier)
299 : {
300 : return ktime_to_us(ktime_sub(later, earlier));
301 : }
302 :
303 : static inline ktime_t ktime_add_us(const ktime_t kt, const u64 usec)
304 : {
305 : return ktime_add_ns(kt, usec * 1000);
306 : }
307 :
308 : static inline ktime_t ktime_sub_us(const ktime_t kt, const u64 usec)
309 : {
310 : return ktime_sub_ns(kt, usec * 1000);
311 : }
312 :
313 : extern ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs);
314 :
315 : /*
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.
320 : */
321 : #define LOW_RES_NSEC TICK_NSEC
322 : #define KTIME_LOW_RES (ktime_t){ .tv64 = LOW_RES_NSEC }
323 :
324 : /* Get the monotonic time in timespec format: */
325 : extern void ktime_get_ts(struct timespec *ts);
326 :
327 : /* Get the real (wall-) time in timespec format: */
328 : #define ktime_get_real_ts(ts) getnstimeofday(ts)
329 :
330 : static inline ktime_t ns_to_ktime(u64 ns)
331 : {
332 : static const ktime_t ktime_zero = { .tv64 = 0 };
333 : return ktime_add_ns(ktime_zero, ns);
334 : }
335 :
336 : #endif
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