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  *  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 typedef union {
  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 } ktime_t;
  58
  59 #define KTIME_MAX                       (~((u64)1 << 63))
  60
  61 /*
  62  * ktime_t definitions when using the 64-bit scalar representation:
  63  */
  64
  65 #if (BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)
  66
  67 /* Define a ktime_t variable and initialize it to zero: */
  68 #define DEFINE_KTIME(kt)                ktime_t kt = { .tv64 = 0 }
  69
  70 /**
  71  * ktime_set - Set a ktime_t variable from a seconds/nanoseconds value
  72  *
  73  * @secs:       seconds to set
  74  * @nsecs:      nanoseconds to set
  75  *
  76  * Return the ktime_t representation of the value
  77  */
  78 static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
  79 {
  80         return (ktime_t) { .tv64 = (s64)secs * NSEC_PER_SEC + (s64)nsecs };
  81 }
  82
  83 /* Subtract two ktime_t variables. rem = lhs -rhs: */
  84 #define ktime_sub(lhs, rhs) \
  85                 ({ (ktime_t){ .tv64 = (lhs).tv64 - (rhs).tv64 }; })
  86
  87 /* Add two ktime_t variables. res = lhs + rhs: */
  88 #define ktime_add(lhs, rhs) \
  89                 ({ (ktime_t){ .tv64 = (lhs).tv64 + (rhs).tv64 }; })
  90
  91 /*
  92  * Add a ktime_t variable and a scalar nanosecond value.
  93  * res = kt + nsval:
  94  */
  95 #define ktime_add_ns(kt, nsval) \
  96                 ({ (ktime_t){ .tv64 = (kt).tv64 + (nsval) }; })
  97
  98 /* convert a timespec to ktime_t format: */
  99 static inline ktime_t timespec_to_ktime(struct timespec ts)
 100 {
 101         return ktime_set(ts.tv_sec, ts.tv_nsec);
 102 }
 103
 104 /* convert a timeval to ktime_t format: */
 105 static inline ktime_t timeval_to_ktime(struct timeval tv)
 106 {
 107         return ktime_set(tv.tv_sec, tv.tv_usec * NSEC_PER_USEC);
 108 }
 109
 110 /* Map the ktime_t to timespec conversion to ns_to_timespec function */
 111 #define ktime_to_timespec(kt)           ns_to_timespec((kt).tv64)
 112
 113 /* Map the ktime_t to timeval conversion to ns_to_timeval function */
 114 #define ktime_to_timeval(kt)            ns_to_timeval((kt).tv64)
 115
 116 /* Map the ktime_t to clock_t conversion to the inline in jiffies.h: */
 117 #define ktime_to_clock_t(kt)            nsec_to_clock_t((kt).tv64)
 118
 119 /* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
 120 #define ktime_to_ns(kt)                 ((kt).tv64)
 121
 122 #else
 123
 124 /*
 125  * Helper macros/inlines to get the ktime_t math right in the timespec
 126  * representation. The macros are sometimes ugly - their actual use is
 127  * pretty okay-ish, given the circumstances. We do all this for
 128  * performance reasons. The pure scalar nsec_t based code was nice and
 129  * simple, but created too many 64-bit / 32-bit conversions and divisions.
 130  *
 131  * Be especially aware that negative values are represented in a way
 132  * that the tv.sec field is negative and the tv.nsec field is greater
 133  * or equal to zero but less than nanoseconds per second. This is the
 134  * same representation which is used by timespecs.
 135  *
 136  *   tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC
 137  */
 138
 139 /* Define a ktime_t variable and initialize it to zero: */
 140 #define DEFINE_KTIME(kt)                ktime_t kt = { .tv64 = 0 }
 141
 142 /* Set a ktime_t variable to a value in sec/nsec representation: */
 143 static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
 144 {
 145         return (ktime_t) { .tv = { .sec = secs, .nsec = nsecs } };
 146 }
 147
 148 /**
 149  * ktime_sub - subtract two ktime_t variables
 150  *
 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  *
 170  * @add1:       addend1
 171  * @add2:       addend2
 172  *
 173  * Returns the sum of addend1 and addend2
 174  */
 175 static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2)
 176 {
 177         ktime_t res;
 178
 179         res.tv64 = add1.tv64 + add2.tv64;
 180         /*
 181          * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx
 182          * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit.
 183          *
 184          * it's equivalent to:
 185          *   tv.nsec -= NSEC_PER_SEC
 186          *   tv.sec ++;
 187          */
 188         if (res.tv.nsec >= NSEC_PER_SEC)
 189                 res.tv64 += (u32)-NSEC_PER_SEC;
 190
 191         return res;
 192 }
 193
 194 /**
 195  * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
 196  *
 197  * @kt:         addend
 198  * @nsec:       the scalar nsec value to add
 199  *
 200  * Returns the sum of kt and nsec in ktime_t format
 201  */
 202 extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec);
 203
 204 /**
 205  * timespec_to_ktime - convert a timespec to ktime_t format
 206  *
 207  * @ts:         the timespec variable to convert
 208  *
 209  * Returns a ktime_t variable with the converted timespec value
 210  */
 211 static inline ktime_t timespec_to_ktime(const struct timespec ts)
 212 {
 213         return (ktime_t) { .tv = { .sec = (s32)ts.tv_sec,
 214                                    .nsec = (s32)ts.tv_nsec } };
 215 }
 216
 217 /**
 218  * timeval_to_ktime - convert a timeval to ktime_t format
 219  *
 220  * @tv:         the timeval variable to convert
 221  *
 222  * Returns a ktime_t variable with the converted timeval value
 223  */
 224 static inline ktime_t timeval_to_ktime(const struct timeval tv)
 225 {
 226         return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec,
 227                                    .nsec = (s32)tv.tv_usec * 1000 } };
 228 }
 229
 230 /**
 231  * ktime_to_timespec - convert a ktime_t variable to timespec format
 232  *
 233  * @kt:         the ktime_t variable to convert
 234  *
 235  * Returns the timespec representation of the ktime value
 236  */
 237 static inline struct timespec ktime_to_timespec(const ktime_t kt)
 238 {
 239         return (struct timespec) { .tv_sec = (time_t) kt.tv.sec,
 240                                    .tv_nsec = (long) kt.tv.nsec };
 241 }
 242
 243 /**
 244  * ktime_to_timeval - convert a ktime_t variable to timeval format
 245  *
 246  * @kt:         the ktime_t variable to convert
 247  *
 248  * Returns the timeval representation of the ktime value
 249  */
 250 static inline struct timeval ktime_to_timeval(const ktime_t kt)
 251 {
 252         return (struct timeval) {
 253                 .tv_sec = (time_t) kt.tv.sec,
 254                 .tv_usec = (suseconds_t) (kt.tv.nsec / NSEC_PER_USEC) };
 255 }
 256
 257 /**
 258  * ktime_to_clock_t - convert a ktime_t variable to clock_t format
 259  * @kt:         the ktime_t variable to convert
 260  *
 261  * Returns a clock_t variable with the converted value
 262  */
 263 static inline clock_t ktime_to_clock_t(const ktime_t kt)
 264 {
 265         return nsec_to_clock_t( (u64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec);
 266 }
 267
 268 /**
 269  * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds
 270  * @kt:         the ktime_t variable to convert
 271  *
 272  * Returns the scalar nanoseconds representation of kt
 273  */
 274 static inline u64 ktime_to_ns(const ktime_t kt)
 275 {
 276         return (u64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec;
 277 }
 278
 279 #endif
 280
 281 /*
 282  * The resolution of the clocks. The resolution value is returned in
 283  * the clock_getres() system call to give application programmers an
 284  * idea of the (in)accuracy of timers. Timer values are rounded up to
 285  * this resolution values.
 286  */
 287 #define KTIME_REALTIME_RES      (ktime_t){ .tv64 = TICK_NSEC }
 288 #define KTIME_MONOTONIC_RES     (ktime_t){ .tv64 = TICK_NSEC }
 289
 290 /* Get the monotonic time in timespec format: */
 291 extern void ktime_get_ts(struct timespec *ts);
 292
 293 /* Get the real (wall-) time in timespec format: */
 294 #define ktime_get_real_ts(ts)   getnstimeofday(ts)
 295
 296 #endif