include/linux/ktime.h

   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  *  For licencing details see kernel-base/COPYING
  14  */
  15 #ifndef _LINUX_KTIME_H
  16 #define _LINUX_KTIME_H
  17
  18 #include <linux/time.h>
  19 #include <linux/jiffies.h>
  20
  21 /*
  22  * ktime_t:
  23  *
  24  * On 64-bit CPUs a single 64-bit variable is used to store the hrtimers
  25  * internal representation of time values in scalar nanoseconds. The
  26  * design plays out best on 64-bit CPUs, where most conversions are
  27  * NOPs and most arithmetic ktime_t operations are plain arithmetic
  28  * operations.
  29  *
  30  * On 32-bit CPUs an optimized representation of the timespec structure
  31  * is used to avoid expensive conversions from and to timespecs. The
  32  * endian-aware order of the tv struct members is choosen to allow
  33  * mathematical operations on the tv64 member of the union too, which
  34  * for certain operations produces better code.
  35  *
  36  * For architectures with efficient support for 64/32-bit conversions the
  37  * plain scalar nanosecond based representation can be selected by the
  38  * config switch CONFIG_KTIME_SCALAR.
  39  */
  40 typedef union {
  41         s64     tv64;
  42 #if BITS_PER_LONG != 64 && !defined(CONFIG_KTIME_SCALAR)
  43         struct {
  44 # ifdef __BIG_ENDIAN
  45         s32     sec, nsec;
  46 # else
  47         s32     nsec, sec;
  48 # endif
  49         } tv;
  50 #endif
  51 } ktime_t;
  52
  53 #define KTIME_MAX                       (~((u64)1 << 63))
  54
  55 /*
  56  * ktime_t definitions when using the 64-bit scalar representation:
  57  */
  58
  59 #if (BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)
  60
  61 /* Define a ktime_t variable and initialize it to zero: */
  62 #define DEFINE_KTIME(kt)                ktime_t kt = { .tv64 = 0 }
  63
  64 /**
  65  * ktime_set - Set a ktime_t variable from a seconds/nanoseconds value
  66  *
  67  * @secs:       seconds to set
  68  * @nsecs:      nanoseconds to set
  69  *
  70  * Return the ktime_t representation of the value
  71  */
  72 static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
  73 {
  74         return (ktime_t) { .tv64 = (s64)secs * NSEC_PER_SEC + (s64)nsecs };
  75 }
  76
  77 /* Subtract two ktime_t variables. rem = lhs -rhs: */
  78 #define ktime_sub(lhs, rhs) \
  79                 ({ (ktime_t){ .tv64 = (lhs).tv64 - (rhs).tv64 }; })
  80
  81 /* Add two ktime_t variables. res = lhs + rhs: */
  82 #define ktime_add(lhs, rhs) \
  83                 ({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; })
  84
  85 /*
  86  * Add a ktime_t variable and a scalar nanosecond value.
  87  * res = kt + nsval:
  88  */
  89 #define ktime_add_ns(kt, nsval) \
  90                 ({ (ktime_t){ .tv64 = (kt).tv64 + (nsval) }; })
  91
  92 /* convert a timespec to ktime_t format: */
  93 #define timespec_to_ktime(ts)           ktime_set((ts).tv_sec, (ts).tv_nsec)
  94
  95 /* convert a timeval to ktime_t format: */
  96 #define timeval_to_ktime(tv)            ktime_set((tv).tv_sec, (tv).tv_usec * 1000)
  97
  98 /* Map the ktime_t to timespec conversion to ns_to_timespec function */
  99 #define ktime_to_timespec(kt)           ns_to_timespec((kt).tv64)
 100
 101 /* Map the ktime_t to timeval conversion to ns_to_timeval function */
 102 #define ktime_to_timeval(kt)            ns_to_timeval((kt).tv64)
 103
 104 /* Map the ktime_t to clock_t conversion to the inline in jiffies.h: */
 105 #define ktime_to_clock_t(kt)            nsec_to_clock_t((kt).tv64)
 106
 107 /* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
 108 #define ktime_to_ns(kt)                 ((kt).tv64)
 109
 110 #else
 111
 112 /*
 113  * Helper macros/inlines to get the ktime_t math right in the timespec
 114  * representation. The macros are sometimes ugly - their actual use is
 115  * pretty okay-ish, given the circumstances. We do all this for
 116  * performance reasons. The pure scalar nsec_t based code was nice and
 117  * simple, but created too many 64-bit / 32-bit conversions and divisions.
 118  *
 119  * Be especially aware that negative values are represented in a way
 120  * that the tv.sec field is negative and the tv.nsec field is greater
 121  * or equal to zero but less than nanoseconds per second. This is the
 122  * same representation which is used by timespecs.
 123  *
 124  *   tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC
 125  */
 126
 127 /* Define a ktime_t variable and initialize it to zero: */
 128 #define DEFINE_KTIME(kt)                ktime_t kt = { .tv64 = 0 }
 129
 130 /* Set a ktime_t variable to a value in sec/nsec representation: */
 131 static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
 132 {
 133         return (ktime_t) { .tv = { .sec = secs, .nsec = nsecs } };
 134 }
 135
 136 /**
 137  * ktime_sub - subtract two ktime_t variables
 138  *
 139  * @lhs:        minuend
 140  * @rhs:        subtrahend
 141  *
 142  * Returns the remainder of the substraction
 143  */
 144 static inline ktime_t ktime_sub(const ktime_t lhs, const ktime_t rhs)
 145 {
 146         ktime_t res;
 147
 148         res.tv64 = lhs.tv64 - rhs.tv64;
 149         if (res.tv.nsec < 0)
 150                 res.tv.nsec += NSEC_PER_SEC;
 151
 152         return res;
 153 }
 154
 155 /**
 156  * ktime_add - add two ktime_t variables
 157  *
 158  * @add1:       addend1
 159  * @add2:       addend2
 160  *
 161  * Returns the sum of addend1 and addend2
 162  */
 163 static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2)
 164 {
 165         ktime_t res;
 166
 167         res.tv64 = add1.tv64 + add2.tv64;
 168         /*
 169          * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx
 170          * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit.
 171          *
 172          * it's equivalent to:
 173          *   tv.nsec -= NSEC_PER_SEC
 174          *   tv.sec ++;
 175          */
 176         if (res.tv.nsec >= NSEC_PER_SEC)
 177                 res.tv64 += (u32)-NSEC_PER_SEC;
 178
 179         return res;
 180 }
 181
 182 /**
 183  * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
 184  *
 185  * @kt:         addend
 186  * @nsec:       the scalar nsec value to add
 187  *
 188  * Returns the sum of kt and nsec in ktime_t format
 189  */
 190 extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec);
 191
 192 /**
 193  * timespec_to_ktime - convert a timespec to ktime_t format
 194  *
 195  * @ts:         the timespec variable to convert
 196  *
 197  * Returns a ktime_t variable with the converted timespec value
 198  */
 199 static inline ktime_t timespec_to_ktime(const struct timespec ts)
 200 {
 201         return (ktime_t) { .tv = { .sec = (s32)ts.tv_sec,
 202                                    .nsec = (s32)ts.tv_nsec } };
 203 }
 204
 205 /**
 206  * timeval_to_ktime - convert a timeval to ktime_t format
 207  *
 208  * @tv:         the timeval variable to convert
 209  *
 210  * Returns a ktime_t variable with the converted timeval value
 211  */
 212 static inline ktime_t timeval_to_ktime(const struct timeval tv)
 213 {
 214         return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec,
 215                                    .nsec = (s32)tv.tv_usec * 1000 } };
 216 }
 217
 218 /**
 219  * ktime_to_timespec - convert a ktime_t variable to timespec format
 220  *
 221  * @kt:         the ktime_t variable to convert
 222  *
 223  * Returns the timespec representation of the ktime value
 224  */
 225 static inline struct timespec ktime_to_timespec(const ktime_t kt)
 226 {
 227         return (struct timespec) { .tv_sec = (time_t) kt.tv.sec,
 228                                    .tv_nsec = (long) kt.tv.nsec };
 229 }
 230
 231 /**
 232  * ktime_to_timeval - convert a ktime_t variable to timeval format
 233  *
 234  * @kt:         the ktime_t variable to convert
 235  *
 236  * Returns the timeval representation of the ktime value
 237  */
 238 static inline struct timeval ktime_to_timeval(const ktime_t kt)
 239 {
 240         return (struct timeval) {
 241                 .tv_sec = (time_t) kt.tv.sec,
 242                 .tv_usec = (suseconds_t) (kt.tv.nsec / NSEC_PER_USEC) };
 243 }
 244
 245 /**
 246  * ktime_to_clock_t - convert a ktime_t variable to clock_t format
 247  * @kt:         the ktime_t variable to convert
 248  *
 249  * Returns a clock_t variable with the converted value
 250  */
 251 static inline clock_t ktime_to_clock_t(const ktime_t kt)
 252 {
 253         return nsec_to_clock_t( (u64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec);
 254 }
 255
 256 /**
 257  * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds
 258  * @kt:         the ktime_t variable to convert
 259  *
 260  * Returns the scalar nanoseconds representation of kt
 261  */
 262 static inline u64 ktime_to_ns(const ktime_t kt)
 263 {
 264         return (u64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec;
 265 }
 266
 267 #endif
 268
 269 /*
 270  * The resolution of the clocks. The resolution value is returned in
 271  * the clock_getres() system call to give application programmers an
 272  * idea of the (in)accuracy of timers. Timer values are rounded up to
 273  * this resolution values.
 274  */
 275 #define KTIME_REALTIME_RES      (NSEC_PER_SEC/HZ)
 276 #define KTIME_MONOTONIC_RES     (NSEC_PER_SEC/HZ)
 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