ktime.h 7.5 KB

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  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. #include <linux/time.h>
  24. #include <linux/jiffies.h>
  25. /*
  26. * ktime_t:
  27. *
  28. * On 64-bit CPUs a single 64-bit variable is used to store the hrtimers
  29. * internal representation of time values in scalar nanoseconds. The
  30. * design plays out best on 64-bit CPUs, where most conversions are
  31. * NOPs and most arithmetic ktime_t operations are plain arithmetic
  32. * operations.
  33. *
  34. * On 32-bit CPUs an optimized representation of the timespec structure
  35. * is used to avoid expensive conversions from and to timespecs. The
  36. * endian-aware order of the tv struct members is choosen to allow
  37. * mathematical operations on the tv64 member of the union too, which
  38. * for certain operations produces better code.
  39. *
  40. * For architectures with efficient support for 64/32-bit conversions the
  41. * plain scalar nanosecond based representation can be selected by the
  42. * config switch CONFIG_KTIME_SCALAR.
  43. */
  44. typedef union {
  45. s64 tv64;
  46. #if BITS_PER_LONG != 64 && !defined(CONFIG_KTIME_SCALAR)
  47. struct {
  48. # ifdef __BIG_ENDIAN
  49. s32 sec, nsec;
  50. # else
  51. s32 nsec, sec;
  52. # endif
  53. } tv;
  54. #endif
  55. } ktime_t;
  56. #define KTIME_MAX ((s64)~((u64)1 << 63))
  57. #if (BITS_PER_LONG == 64)
  58. # define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC)
  59. #else
  60. # define KTIME_SEC_MAX LONG_MAX
  61. #endif
  62. /*
  63. * ktime_t definitions when using the 64-bit scalar representation:
  64. */
  65. #if (BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)
  66. /**
  67. * ktime_set - Set a ktime_t variable from a seconds/nanoseconds value
  68. * @secs: seconds to set
  69. * @nsecs: nanoseconds to set
  70. *
  71. * Return the ktime_t representation of the value
  72. */
  73. static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
  74. {
  75. #if (BITS_PER_LONG == 64)
  76. if (unlikely(secs >= KTIME_SEC_MAX))
  77. return (ktime_t){ .tv64 = KTIME_MAX };
  78. #endif
  79. return (ktime_t) { .tv64 = (s64)secs * NSEC_PER_SEC + (s64)nsecs };
  80. }
  81. /* Subtract two ktime_t variables. rem = lhs -rhs: */
  82. #define ktime_sub(lhs, rhs) \
  83. ({ (ktime_t){ .tv64 = (lhs).tv64 - (rhs).tv64 }; })
  84. /* Add two ktime_t variables. res = lhs + rhs: */
  85. #define ktime_add(lhs, rhs) \
  86. ({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; })
  87. /*
  88. * Add a ktime_t variable and a scalar nanosecond value.
  89. * res = kt + nsval:
  90. */
  91. #define ktime_add_ns(kt, nsval) \
  92. ({ (ktime_t){ .tv64 = (kt).tv64 + (nsval) }; })
  93. /* convert a timespec to ktime_t format: */
  94. static inline ktime_t timespec_to_ktime(struct timespec ts)
  95. {
  96. return ktime_set(ts.tv_sec, ts.tv_nsec);
  97. }
  98. /* convert a timeval to ktime_t format: */
  99. static inline ktime_t timeval_to_ktime(struct timeval tv)
  100. {
  101. return ktime_set(tv.tv_sec, tv.tv_usec * NSEC_PER_USEC);
  102. }
  103. /* Map the ktime_t to timespec conversion to ns_to_timespec function */
  104. #define ktime_to_timespec(kt) ns_to_timespec((kt).tv64)
  105. /* Map the ktime_t to timeval conversion to ns_to_timeval function */
  106. #define ktime_to_timeval(kt) ns_to_timeval((kt).tv64)
  107. /* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
  108. #define ktime_to_ns(kt) ((kt).tv64)
  109. #else
  110. /*
  111. * Helper macros/inlines to get the ktime_t math right in the timespec
  112. * representation. The macros are sometimes ugly - their actual use is
  113. * pretty okay-ish, given the circumstances. We do all this for
  114. * performance reasons. The pure scalar nsec_t based code was nice and
  115. * simple, but created too many 64-bit / 32-bit conversions and divisions.
  116. *
  117. * Be especially aware that negative values are represented in a way
  118. * that the tv.sec field is negative and the tv.nsec field is greater
  119. * or equal to zero but less than nanoseconds per second. This is the
  120. * same representation which is used by timespecs.
  121. *
  122. * tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC
  123. */
  124. /* Set a ktime_t variable to a value in sec/nsec representation: */
  125. static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
  126. {
  127. return (ktime_t) { .tv = { .sec = secs, .nsec = nsecs } };
  128. }
  129. /**
  130. * ktime_sub - subtract two ktime_t variables
  131. * @lhs: minuend
  132. * @rhs: subtrahend
  133. *
  134. * Returns the remainder of the substraction
  135. */
  136. static inline ktime_t ktime_sub(const ktime_t lhs, const ktime_t rhs)
  137. {
  138. ktime_t res;
  139. res.tv64 = lhs.tv64 - rhs.tv64;
  140. if (res.tv.nsec < 0)
  141. res.tv.nsec += NSEC_PER_SEC;
  142. return res;
  143. }
  144. /**
  145. * ktime_add - add two ktime_t variables
  146. * @add1: addend1
  147. * @add2: addend2
  148. *
  149. * Returns the sum of @add1 and @add2.
  150. */
  151. static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2)
  152. {
  153. ktime_t res;
  154. res.tv64 = add1.tv64 + add2.tv64;
  155. /*
  156. * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx
  157. * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit.
  158. *
  159. * it's equivalent to:
  160. * tv.nsec -= NSEC_PER_SEC
  161. * tv.sec ++;
  162. */
  163. if (res.tv.nsec >= NSEC_PER_SEC)
  164. res.tv64 += (u32)-NSEC_PER_SEC;
  165. return res;
  166. }
  167. /**
  168. * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
  169. * @kt: addend
  170. * @nsec: the scalar nsec value to add
  171. *
  172. * Returns the sum of @kt and @nsec in ktime_t format
  173. */
  174. extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec);
  175. /**
  176. * timespec_to_ktime - convert a timespec to ktime_t format
  177. * @ts: the timespec variable to convert
  178. *
  179. * Returns a ktime_t variable with the converted timespec value
  180. */
  181. static inline ktime_t timespec_to_ktime(const struct timespec ts)
  182. {
  183. return (ktime_t) { .tv = { .sec = (s32)ts.tv_sec,
  184. .nsec = (s32)ts.tv_nsec } };
  185. }
  186. /**
  187. * timeval_to_ktime - convert a timeval to ktime_t format
  188. * @tv: the timeval variable to convert
  189. *
  190. * Returns a ktime_t variable with the converted timeval value
  191. */
  192. static inline ktime_t timeval_to_ktime(const struct timeval tv)
  193. {
  194. return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec,
  195. .nsec = (s32)tv.tv_usec * 1000 } };
  196. }
  197. /**
  198. * ktime_to_timespec - convert a ktime_t variable to timespec format
  199. * @kt: the ktime_t variable to convert
  200. *
  201. * Returns the timespec representation of the ktime value
  202. */
  203. static inline struct timespec ktime_to_timespec(const ktime_t kt)
  204. {
  205. return (struct timespec) { .tv_sec = (time_t) kt.tv.sec,
  206. .tv_nsec = (long) kt.tv.nsec };
  207. }
  208. /**
  209. * ktime_to_timeval - convert a ktime_t variable to timeval format
  210. * @kt: the ktime_t variable to convert
  211. *
  212. * Returns the timeval representation of the ktime value
  213. */
  214. static inline struct timeval ktime_to_timeval(const ktime_t kt)
  215. {
  216. return (struct timeval) {
  217. .tv_sec = (time_t) kt.tv.sec,
  218. .tv_usec = (suseconds_t) (kt.tv.nsec / NSEC_PER_USEC) };
  219. }
  220. /**
  221. * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds
  222. * @kt: the ktime_t variable to convert
  223. *
  224. * Returns the scalar nanoseconds representation of @kt
  225. */
  226. static inline s64 ktime_to_ns(const ktime_t kt)
  227. {
  228. return (s64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec;
  229. }
  230. #endif
  231. /*
  232. * The resolution of the clocks. The resolution value is returned in
  233. * the clock_getres() system call to give application programmers an
  234. * idea of the (in)accuracy of timers. Timer values are rounded up to
  235. * this resolution values.
  236. */
  237. #define KTIME_LOW_RES (ktime_t){ .tv64 = TICK_NSEC }
  238. /* Get the monotonic time in timespec format: */
  239. extern void ktime_get_ts(struct timespec *ts);
  240. /* Get the real (wall-) time in timespec format: */
  241. #define ktime_get_real_ts(ts) getnstimeofday(ts)
  242. #endif