include/linux/units.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_UNITS_H
   3 #define _LINUX_UNITS_H
   4
   5 #include <linux/bits.h>
   6 #include <linux/math.h>
   7
   8 /* Metric prefixes in accordance with Système international (d'unités) */
   9 #define PETA    1000000000000000ULL
  10 #define TERA    1000000000000ULL
  11 #define GIGA    1000000000UL
  12 #define MEGA    1000000UL
  13 #define KILO    1000UL
  14 #define HECTO   100UL
  15 #define DECA    10UL
  16 #define DECI    10UL
  17 #define CENTI   100UL
  18 #define MILLI   1000UL
  19 #define MICRO   1000000UL
  20 #define NANO    1000000000UL
  21 #define PICO    1000000000000ULL
  22 #define FEMTO   1000000000000000ULL
  23
  24 #define NANOHZ_PER_HZ           1000000000UL
  25 #define MICROHZ_PER_HZ          1000000UL
  26 #define MILLIHZ_PER_HZ          1000UL
  27
  28 #define HZ_PER_KHZ              1000UL
  29 #define HZ_PER_MHZ              1000000UL
  30
  31 #define KHZ_PER_MHZ             1000UL
  32 #define KHZ_PER_GHZ             1000000UL
  33
  34 #define MILLIWATT_PER_WATT      1000UL
  35 #define MICROWATT_PER_MILLIWATT 1000UL
  36 #define MICROWATT_PER_WATT      1000000UL
  37
  38 #define BYTES_PER_KBIT          (KILO / BITS_PER_BYTE)
  39 #define BYTES_PER_MBIT          (MEGA / BITS_PER_BYTE)
  40 #define BYTES_PER_GBIT          (GIGA / BITS_PER_BYTE)
  41
  42 #define ABSOLUTE_ZERO_MILLICELSIUS -273150
  43
  44 static inline long milli_kelvin_to_millicelsius(long t)
  45 {
  46         return t + ABSOLUTE_ZERO_MILLICELSIUS;
  47 }
  48
  49 static inline long millicelsius_to_milli_kelvin(long t)
  50 {
  51         return t - ABSOLUTE_ZERO_MILLICELSIUS;
  52 }
  53
  54 #define MILLIDEGREE_PER_DEGREE 1000
  55 #define MILLIDEGREE_PER_DECIDEGREE 100
  56
  57 static inline long kelvin_to_millicelsius(long t)
  58 {
  59         return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DEGREE);
  60 }
  61
  62 static inline long millicelsius_to_kelvin(long t)
  63 {
  64         t = millicelsius_to_milli_kelvin(t);
  65
  66         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
  67 }
  68
  69 static inline long deci_kelvin_to_celsius(long t)
  70 {
  71         t = milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
  72
  73         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
  74 }
  75
  76 static inline long celsius_to_deci_kelvin(long t)
  77 {
  78         t = millicelsius_to_milli_kelvin(t * MILLIDEGREE_PER_DEGREE);
  79
  80         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
  81 }
  82
  83 /**
  84  * deci_kelvin_to_millicelsius_with_offset - convert Kelvin to Celsius
  85  * @t: temperature value in decidegrees Kelvin
  86  * @offset: difference between Kelvin and Celsius in millidegrees
  87  *
  88  * Return: temperature value in millidegrees Celsius
  89  */
  90 static inline long deci_kelvin_to_millicelsius_with_offset(long t, long offset)
  91 {
  92         return t * MILLIDEGREE_PER_DECIDEGREE - offset;
  93 }
  94
  95 static inline long deci_kelvin_to_millicelsius(long t)
  96 {
  97         return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
  98 }
  99
 100 static inline long millicelsius_to_deci_kelvin(long t)
 101 {
 102         t = millicelsius_to_milli_kelvin(t);
 103
 104         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
 105 }
 106
 107 static inline long kelvin_to_celsius(long t)
 108 {
 109         return t + DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
 110                                      MILLIDEGREE_PER_DEGREE);
 111 }
 112
 113 static inline long celsius_to_kelvin(long t)
 114 {
 115         return t - DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
 116                                      MILLIDEGREE_PER_DEGREE);
 117 }
 118
 119 #endif /* _LINUX_UNITS_H */