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 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 #endif
331
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