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 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 /**
 265  * ktime_equal - Compares two ktime_t variables to see if they are equal
 266  * @cmp1:       comparable1
 267  * @cmp2:       comparable2
 268  *
 269  * Compare two ktime_t variables, returns 1 if equal
 270  */
 271 static inline int ktime_equal(const ktime_t cmp1, const ktime_t cmp2)
 272 {
 273         return cmp1.tv64 == cmp2.tv64;
 274 }
 275
 276 static inline s64 ktime_to_us(const ktime_t kt)
 277 {
 278         struct timeval tv = ktime_to_timeval(kt);
 279         return (s64) tv.tv_sec * USEC_PER_SEC + tv.tv_usec;
 280 }
 281
 282 static inline s64 ktime_us_delta(const ktime_t later, const ktime_t earlier)
 283 {
 284        return ktime_to_us(ktime_sub(later, earlier));
 285 }
 286
 287 static inline ktime_t ktime_add_us(const ktime_t kt, const u64 usec)
 288 {
 289         return ktime_add_ns(kt, usec * 1000);
 290 }
 291
 292 /*
 293  * The resolution of the clocks. The resolution value is returned in
 294  * the clock_getres() system call to give application programmers an
 295  * idea of the (in)accuracy of timers. Timer values are rounded up to
 296  * this resolution values.
 297  */
 298 #define KTIME_LOW_RES           (ktime_t){ .tv64 = TICK_NSEC }
 299
 300 /* Get the monotonic time in timespec format: */
 301 extern void ktime_get_ts(struct timespec *ts);
 302
 303 /* Get the real (wall-) time in timespec format: */
 304 #define ktime_get_real_ts(ts)   getnstimeofday(ts)
 305
 306 #endif