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 #include <asm/bug.h>
  27
  28 /* Nanosecond scalar representation for kernel time values */
  29 typedef s64     ktime_t;
  30
  31 /**
  32  * ktime_set - Set a ktime_t variable from a seconds/nanoseconds value
  33  * @secs:       seconds to set
  34  * @nsecs:      nanoseconds to set
  35  *
  36  * Return: The ktime_t representation of the value.
  37  */
  38 static inline ktime_t ktime_set(const s64 secs, const unsigned long nsecs)
  39 {
  40         if (unlikely(secs >= KTIME_SEC_MAX))
  41                 return KTIME_MAX;
  42
  43         return secs * NSEC_PER_SEC + (s64)nsecs;
  44 }
  45
  46 /* Subtract two ktime_t variables. rem = lhs -rhs: */
  47 #define ktime_sub(lhs, rhs)     ((lhs) - (rhs))
  48
  49 /* Add two ktime_t variables. res = lhs + rhs: */
  50 #define ktime_add(lhs, rhs)     ((lhs) + (rhs))
  51
  52 /*
  53  * Same as ktime_add(), but avoids undefined behaviour on overflow; however,
  54  * this means that you must check the result for overflow yourself.
  55  */
  56 #define ktime_add_unsafe(lhs, rhs)      ((u64) (lhs) + (rhs))
  57
  58 /*
  59  * Add a ktime_t variable and a scalar nanosecond value.
  60  * res = kt + nsval:
  61  */
  62 #define ktime_add_ns(kt, nsval)         ((kt) + (nsval))
  63
  64 /*
  65  * Subtract a scalar nanosecod from a ktime_t variable
  66  * res = kt - nsval:
  67  */
  68 #define ktime_sub_ns(kt, nsval)         ((kt) - (nsval))
  69
  70 /* convert a timespec64 to ktime_t format: */
  71 static inline ktime_t timespec64_to_ktime(struct timespec64 ts)
  72 {
  73         return ktime_set(ts.tv_sec, ts.tv_nsec);
  74 }
  75
  76 /* Map the ktime_t to timespec conversion to ns_to_timespec function */
  77 #define ktime_to_timespec64(kt)         ns_to_timespec64((kt))
  78
  79 /* Convert ktime_t to nanoseconds */
  80 static inline s64 ktime_to_ns(const ktime_t kt)
  81 {
  82         return kt;
  83 }
  84
  85 /**
  86  * ktime_compare - Compares two ktime_t variables for less, greater or equal
  87  * @cmp1:       comparable1
  88  * @cmp2:       comparable2
  89  *
  90  * Return: ...
  91  *   cmp1  < cmp2: return <0
  92  *   cmp1 == cmp2: return 0
  93  *   cmp1  > cmp2: return >0
  94  */
  95 static inline int ktime_compare(const ktime_t cmp1, const ktime_t cmp2)
  96 {
  97         if (cmp1 < cmp2)
  98                 return -1;
  99         if (cmp1 > cmp2)
 100                 return 1;
 101         return 0;
 102 }
 103
 104 /**
 105  * ktime_after - Compare if a ktime_t value is bigger than another one.
 106  * @cmp1:       comparable1
 107  * @cmp2:       comparable2
 108  *
 109  * Return: true if cmp1 happened after cmp2.
 110  */
 111 static inline bool ktime_after(const ktime_t cmp1, const ktime_t cmp2)
 112 {
 113         return ktime_compare(cmp1, cmp2) > 0;
 114 }
 115
 116 /**
 117  * ktime_before - Compare if a ktime_t value is smaller than another one.
 118  * @cmp1:       comparable1
 119  * @cmp2:       comparable2
 120  *
 121  * Return: true if cmp1 happened before cmp2.
 122  */
 123 static inline bool ktime_before(const ktime_t cmp1, const ktime_t cmp2)
 124 {
 125         return ktime_compare(cmp1, cmp2) < 0;
 126 }
 127
 128 #if BITS_PER_LONG < 64
 129 extern s64 __ktime_divns(const ktime_t kt, s64 div);
 130 static inline s64 ktime_divns(const ktime_t kt, s64 div)
 131 {
 132         /*
 133          * Negative divisors could cause an inf loop,
 134          * so bug out here.
 135          */
 136         BUG_ON(div < 0);
 137         if (__builtin_constant_p(div) && !(div >> 32)) {
 138                 s64 ns = kt;
 139                 u64 tmp = ns < 0 ? -ns : ns;
 140
 141                 do_div(tmp, div);
 142                 return ns < 0 ? -tmp : tmp;
 143         } else {
 144                 return __ktime_divns(kt, div);
 145         }
 146 }
 147 #else /* BITS_PER_LONG < 64 */
 148 static inline s64 ktime_divns(const ktime_t kt, s64 div)
 149 {
 150         /*
 151          * 32-bit implementation cannot handle negative divisors,
 152          * so catch them on 64bit as well.
 153          */
 154         WARN_ON(div < 0);
 155         return kt / div;
 156 }
 157 #endif
 158
 159 static inline s64 ktime_to_us(const ktime_t kt)
 160 {
 161         return ktime_divns(kt, NSEC_PER_USEC);
 162 }
 163
 164 static inline s64 ktime_to_ms(const ktime_t kt)
 165 {
 166         return ktime_divns(kt, NSEC_PER_MSEC);
 167 }
 168
 169 static inline s64 ktime_us_delta(const ktime_t later, const ktime_t earlier)
 170 {
 171        return ktime_to_us(ktime_sub(later, earlier));
 172 }
 173
 174 static inline s64 ktime_ms_delta(const ktime_t later, const ktime_t earlier)
 175 {
 176         return ktime_to_ms(ktime_sub(later, earlier));
 177 }
 178
 179 static inline ktime_t ktime_add_us(const ktime_t kt, const u64 usec)
 180 {
 181         return ktime_add_ns(kt, usec * NSEC_PER_USEC);
 182 }
 183
 184 static inline ktime_t ktime_add_ms(const ktime_t kt, const u64 msec)
 185 {
 186         return ktime_add_ns(kt, msec * NSEC_PER_MSEC);
 187 }
 188
 189 static inline ktime_t ktime_sub_us(const ktime_t kt, const u64 usec)
 190 {
 191         return ktime_sub_ns(kt, usec * NSEC_PER_USEC);
 192 }
 193
 194 static inline ktime_t ktime_sub_ms(const ktime_t kt, const u64 msec)
 195 {
 196         return ktime_sub_ns(kt, msec * NSEC_PER_MSEC);
 197 }
 198
 199 extern ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs);
 200
 201 /**
 202  * ktime_to_timespec64_cond - convert a ktime_t variable to timespec64
 203  *                          format only if the variable contains data
 204  * @kt:         the ktime_t variable to convert
 205  * @ts:         the timespec variable to store the result in
 206  *
 207  * Return: %true if there was a successful conversion, %false if kt was 0.
 208  */
 209 static inline __must_check bool ktime_to_timespec64_cond(const ktime_t kt,
 210                                                        struct timespec64 *ts)
 211 {
 212         if (kt) {
 213                 *ts = ktime_to_timespec64(kt);
 214                 return true;
 215         } else {
 216                 return false;
 217         }
 218 }
 219
 220 #include <vdso/ktime.h>
 221
 222 static inline ktime_t ns_to_ktime(u64 ns)
 223 {
 224         return ns;
 225 }
 226
 227 static inline ktime_t ms_to_ktime(u64 ms)
 228 {
 229         return ms * NSEC_PER_MSEC;
 230 }
 231
 232 # include <linux/timekeeping.h>
 233
 234 #endif