xref: /openbmc/linux/include/linux/ktime.h (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 /* convert a timespec to ktime_t format: */
106 static inline ktime_t timespec_to_ktime(struct timespec ts)
107 {
108 	return ktime_set(ts.tv_sec, ts.tv_nsec);
109 }
110 
111 /* convert a timeval to ktime_t format: */
112 static inline ktime_t timeval_to_ktime(struct timeval tv)
113 {
114 	return ktime_set(tv.tv_sec, tv.tv_usec * NSEC_PER_USEC);
115 }
116 
117 /* Map the ktime_t to timespec conversion to ns_to_timespec function */
118 #define ktime_to_timespec(kt)		ns_to_timespec((kt).tv64)
119 
120 /* Map the ktime_t to timeval conversion to ns_to_timeval function */
121 #define ktime_to_timeval(kt)		ns_to_timeval((kt).tv64)
122 
123 /* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
124 #define ktime_to_ns(kt)			((kt).tv64)
125 
126 #else
127 
128 /*
129  * Helper macros/inlines to get the ktime_t math right in the timespec
130  * representation. The macros are sometimes ugly - their actual use is
131  * pretty okay-ish, given the circumstances. We do all this for
132  * performance reasons. The pure scalar nsec_t based code was nice and
133  * simple, but created too many 64-bit / 32-bit conversions and divisions.
134  *
135  * Be especially aware that negative values are represented in a way
136  * that the tv.sec field is negative and the tv.nsec field is greater
137  * or equal to zero but less than nanoseconds per second. This is the
138  * same representation which is used by timespecs.
139  *
140  *   tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC
141  */
142 
143 /* Set a ktime_t variable to a value in sec/nsec representation: */
144 static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
145 {
146 	return (ktime_t) { .tv = { .sec = secs, .nsec = nsecs } };
147 }
148 
149 /**
150  * ktime_sub - subtract two ktime_t variables
151  * @lhs:	minuend
152  * @rhs:	subtrahend
153  *
154  * Returns the remainder of the substraction
155  */
156 static inline ktime_t ktime_sub(const ktime_t lhs, const ktime_t rhs)
157 {
158 	ktime_t res;
159 
160 	res.tv64 = lhs.tv64 - rhs.tv64;
161 	if (res.tv.nsec < 0)
162 		res.tv.nsec += NSEC_PER_SEC;
163 
164 	return res;
165 }
166 
167 /**
168  * ktime_add - add two ktime_t variables
169  * @add1:	addend1
170  * @add2:	addend2
171  *
172  * Returns the sum of @add1 and @add2.
173  */
174 static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2)
175 {
176 	ktime_t res;
177 
178 	res.tv64 = add1.tv64 + add2.tv64;
179 	/*
180 	 * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx
181 	 * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit.
182 	 *
183 	 * it's equivalent to:
184 	 *   tv.nsec -= NSEC_PER_SEC
185 	 *   tv.sec ++;
186 	 */
187 	if (res.tv.nsec >= NSEC_PER_SEC)
188 		res.tv64 += (u32)-NSEC_PER_SEC;
189 
190 	return res;
191 }
192 
193 /**
194  * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
195  * @kt:		addend
196  * @nsec:	the scalar nsec value to add
197  *
198  * Returns the sum of @kt and @nsec in ktime_t format
199  */
200 extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec);
201 
202 /**
203  * timespec_to_ktime - convert a timespec to ktime_t format
204  * @ts:		the timespec variable to convert
205  *
206  * Returns a ktime_t variable with the converted timespec value
207  */
208 static inline ktime_t timespec_to_ktime(const struct timespec ts)
209 {
210 	return (ktime_t) { .tv = { .sec = (s32)ts.tv_sec,
211 			   	   .nsec = (s32)ts.tv_nsec } };
212 }
213 
214 /**
215  * timeval_to_ktime - convert a timeval to ktime_t format
216  * @tv:		the timeval variable to convert
217  *
218  * Returns a ktime_t variable with the converted timeval value
219  */
220 static inline ktime_t timeval_to_ktime(const struct timeval tv)
221 {
222 	return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec,
223 				   .nsec = (s32)tv.tv_usec * 1000 } };
224 }
225 
226 /**
227  * ktime_to_timespec - convert a ktime_t variable to timespec format
228  * @kt:		the ktime_t variable to convert
229  *
230  * Returns the timespec representation of the ktime value
231  */
232 static inline struct timespec ktime_to_timespec(const ktime_t kt)
233 {
234 	return (struct timespec) { .tv_sec = (time_t) kt.tv.sec,
235 				   .tv_nsec = (long) kt.tv.nsec };
236 }
237 
238 /**
239  * ktime_to_timeval - convert a ktime_t variable to timeval format
240  * @kt:		the ktime_t variable to convert
241  *
242  * Returns the timeval representation of the ktime value
243  */
244 static inline struct timeval ktime_to_timeval(const ktime_t kt)
245 {
246 	return (struct timeval) {
247 		.tv_sec = (time_t) kt.tv.sec,
248 		.tv_usec = (suseconds_t) (kt.tv.nsec / NSEC_PER_USEC) };
249 }
250 
251 /**
252  * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds
253  * @kt:		the ktime_t variable to convert
254  *
255  * Returns the scalar nanoseconds representation of @kt
256  */
257 static inline s64 ktime_to_ns(const ktime_t kt)
258 {
259 	return (s64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec;
260 }
261 
262 #endif
263 
264 static inline s64 ktime_to_us(const ktime_t kt)
265 {
266 	struct timeval tv = ktime_to_timeval(kt);
267 	return (s64) tv.tv_sec * USEC_PER_SEC + tv.tv_usec;
268 }
269 
270 /*
271  * The resolution of the clocks. The resolution value is returned in
272  * the clock_getres() system call to give application programmers an
273  * idea of the (in)accuracy of timers. Timer values are rounded up to
274  * this resolution values.
275  */
276 #define KTIME_LOW_RES		(ktime_t){ .tv64 = TICK_NSEC }
277 
278 /* Get the monotonic time in timespec format: */
279 extern void ktime_get_ts(struct timespec *ts);
280 
281 /* Get the real (wall-) time in timespec format: */
282 #define ktime_get_real_ts(ts)	getnstimeofday(ts)
283 
284 #endif
285