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 chosen 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 /*
 106  * Subtract a scalar nanosecod from a ktime_t variable
 107  * res = kt - nsval:
 108  */
 109 #define ktime_sub_ns(kt, nsval) \
 110                 ({ (ktime_t){ .tv64 = (kt).tv64 - (nsval) }; })
 111
 112 /* convert a timespec to ktime_t format: */
 113 static inline ktime_t timespec_to_ktime(struct timespec ts)
 114 {
 115         return ktime_set(ts.tv_sec, ts.tv_nsec);
 116 }
 117
 118 /* convert a timeval to ktime_t format: */
 119 static inline ktime_t timeval_to_ktime(struct timeval tv)
 120 {
 121         return ktime_set(tv.tv_sec, tv.tv_usec * NSEC_PER_USEC);
 122 }
 123
 124 /* Map the ktime_t to timespec conversion to ns_to_timespec function */
 125 #define ktime_to_timespec(kt)           ns_to_timespec((kt).tv64)
 126
 127 /* Map the ktime_t to timeval conversion to ns_to_timeval function */
 128 #define ktime_to_timeval(kt)            ns_to_timeval((kt).tv64)
 129
 130 /* Convert ktime_t to nanoseconds - NOP in the scalar storage format: */
 131 #define ktime_to_ns(kt)                 ((kt).tv64)
 132
 133 #else   /* !((BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)) */
 134
 135 /*
 136  * Helper macros/inlines to get the ktime_t math right in the timespec
 137  * representation. The macros are sometimes ugly - their actual use is
 138  * pretty okay-ish, given the circumstances. We do all this for
 139  * performance reasons. The pure scalar nsec_t based code was nice and
 140  * simple, but created too many 64-bit / 32-bit conversions and divisions.
 141  *
 142  * Be especially aware that negative values are represented in a way
 143  * that the tv.sec field is negative and the tv.nsec field is greater
 144  * or equal to zero but less than nanoseconds per second. This is the
 145  * same representation which is used by timespecs.
 146  *
 147  *   tv.sec < 0 and 0 >= tv.nsec < NSEC_PER_SEC
 148  */
 149
 150 /* Set a ktime_t variable to a value in sec/nsec representation: */
 151 static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
 152 {
 153         return (ktime_t) { .tv = { .sec = secs, .nsec = nsecs } };
 154 }
 155
 156 /**
 157  * ktime_sub - subtract two ktime_t variables
 158  * @lhs:        minuend
 159  * @rhs:        subtrahend
 160  *
 161  * Returns the remainder of the subtraction
 162  */
 163 static inline ktime_t ktime_sub(const ktime_t lhs, const ktime_t rhs)
 164 {
 165         ktime_t res;
 166
 167         res.tv64 = lhs.tv64 - rhs.tv64;
 168         if (res.tv.nsec < 0)
 169                 res.tv.nsec += NSEC_PER_SEC;
 170
 171         return res;
 172 }
 173
 174 /**
 175  * ktime_add - add two ktime_t variables
 176  * @add1:       addend1
 177  * @add2:       addend2
 178  *
 179  * Returns the sum of @add1 and @add2.
 180  */
 181 static inline ktime_t ktime_add(const ktime_t add1, const ktime_t add2)
 182 {
 183         ktime_t res;
 184
 185         res.tv64 = add1.tv64 + add2.tv64;
 186         /*
 187          * performance trick: the (u32) -NSEC gives 0x00000000Fxxxxxxx
 188          * so we subtract NSEC_PER_SEC and add 1 to the upper 32 bit.
 189          *
 190          * it's equivalent to:
 191          *   tv.nsec -= NSEC_PER_SEC
 192          *   tv.sec ++;
 193          */
 194         if (res.tv.nsec >= NSEC_PER_SEC)
 195                 res.tv64 += (u32)-NSEC_PER_SEC;
 196
 197         return res;
 198 }
 199
 200 /**
 201  * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
 202  * @kt:         addend
 203  * @nsec:       the scalar nsec value to add
 204  *
 205  * Returns the sum of @kt and @nsec in ktime_t format
 206  */
 207 extern ktime_t ktime_add_ns(const ktime_t kt, u64 nsec);
 208
 209 /**
 210  * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
 211  * @kt:         minuend
 212  * @nsec:       the scalar nsec value to subtract
 213  *
 214  * Returns the subtraction of @nsec from @kt in ktime_t format
 215  */
 216 extern ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec);
 217
 218 /**
 219  * timespec_to_ktime - convert a timespec to ktime_t format
 220  * @ts:         the timespec variable to convert
 221  *
 222  * Returns a ktime_t variable with the converted timespec value
 223  */
 224 static inline ktime_t timespec_to_ktime(const struct timespec ts)
 225 {
 226         return (ktime_t) { .tv = { .sec = (s32)ts.tv_sec,
 227                                    .nsec = (s32)ts.tv_nsec } };
 228 }
 229
 230 /**
 231  * timeval_to_ktime - convert a timeval to ktime_t format
 232  * @tv:         the timeval variable to convert
 233  *
 234  * Returns a ktime_t variable with the converted timeval value
 235  */
 236 static inline ktime_t timeval_to_ktime(const struct timeval tv)
 237 {
 238         return (ktime_t) { .tv = { .sec = (s32)tv.tv_sec,
 239                                    .nsec = (s32)tv.tv_usec * 1000 } };
 240 }
 241
 242 /**
 243  * ktime_to_timespec - convert a ktime_t variable to timespec format
 244  * @kt:         the ktime_t variable to convert
 245  *
 246  * Returns the timespec representation of the ktime value
 247  */
 248 static inline struct timespec ktime_to_timespec(const ktime_t kt)
 249 {
 250         return (struct timespec) { .tv_sec = (time_t) kt.tv.sec,
 251                                    .tv_nsec = (long) kt.tv.nsec };
 252 }
 253
 254 /**
 255  * ktime_to_timeval - convert a ktime_t variable to timeval format
 256  * @kt:         the ktime_t variable to convert
 257  *
 258  * Returns the timeval representation of the ktime value
 259  */
 260 static inline struct timeval ktime_to_timeval(const ktime_t kt)
 261 {
 262         return (struct timeval) {
 263                 .tv_sec = (time_t) kt.tv.sec,
 264                 .tv_usec = (suseconds_t) (kt.tv.nsec / NSEC_PER_USEC) };
 265 }
 266
 267 /**
 268  * ktime_to_ns - convert a ktime_t variable to scalar nanoseconds
 269  * @kt:         the ktime_t variable to convert
 270  *
 271  * Returns the scalar nanoseconds representation of @kt
 272  */
 273 static inline s64 ktime_to_ns(const ktime_t kt)
 274 {
 275         return (s64) kt.tv.sec * NSEC_PER_SEC + kt.tv.nsec;
 276 }
 277
 278 #endif  /* !((BITS_PER_LONG == 64) || defined(CONFIG_KTIME_SCALAR)) */
 279
 280 /**
 281  * ktime_equal - Compares two ktime_t variables to see if they are equal
 282  * @cmp1:       comparable1
 283  * @cmp2:       comparable2
 284  *
 285  * Compare two ktime_t variables, returns 1 if equal
 286  */
 287 static inline int ktime_equal(const ktime_t cmp1, const ktime_t cmp2)
 288 {
 289         return cmp1.tv64 == cmp2.tv64;
 290 }
 291
 292 static inline s64 ktime_to_us(const ktime_t kt)
 293 {
 294         struct timeval tv = ktime_to_timeval(kt);
 295         return (s64) tv.tv_sec * USEC_PER_SEC + tv.tv_usec;
 296 }
 297
 298 static inline s64 ktime_to_ms(const ktime_t kt)
 299 {
 300         struct timeval tv = ktime_to_timeval(kt);
 301         return (s64) tv.tv_sec * MSEC_PER_SEC + tv.tv_usec / USEC_PER_MSEC;
 302 }
 303
 304 static inline s64 ktime_us_delta(const ktime_t later, const ktime_t earlier)
 305 {
 306        return ktime_to_us(ktime_sub(later, earlier));
 307 }
 308
 309 static inline ktime_t ktime_add_us(const ktime_t kt, const u64 usec)
 310 {
 311         return ktime_add_ns(kt, usec * 1000);
 312 }
 313
 314 static inline ktime_t ktime_sub_us(const ktime_t kt, const u64 usec)
 315 {
 316         return ktime_sub_ns(kt, usec * 1000);
 317 }
 318
 319 extern ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs);
 320
 321 /*
 322  * The resolution of the clocks. The resolution value is returned in
 323  * the clock_getres() system call to give application programmers an
 324  * idea of the (in)accuracy of timers. Timer values are rounded up to
 325  * this resolution values.
 326  */
 327 #define LOW_RES_NSEC            TICK_NSEC
 328 #define KTIME_LOW_RES           (ktime_t){ .tv64 = LOW_RES_NSEC }
 329
 330 /* Get the monotonic time in timespec format: */
 331 extern void ktime_get_ts(struct timespec *ts);
 332
 333 /* Get the real (wall-) time in timespec format: */
 334 #define ktime_get_real_ts(ts)   getnstimeofday(ts)
 335
 336 static inline ktime_t ns_to_ktime(u64 ns)
 337 {
 338         static const ktime_t ktime_zero = { .tv64 = 0 };
 339         return ktime_add_ns(ktime_zero, ns);
 340 }
 341
 342 #endif