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 #define HZ_PER_KHZ              1000UL
  28 #define KHZ_PER_MHZ             1000UL
  29 #define HZ_PER_MHZ              1000000UL
  30
  31 #define MILLIWATT_PER_WATT      1000UL
  32 #define MICROWATT_PER_MILLIWATT 1000UL
  33 #define MICROWATT_PER_WATT      1000000UL
  34
  35 #define BYTES_PER_KBIT          (KILO / BITS_PER_BYTE)
  36 #define BYTES_PER_MBIT          (MEGA / BITS_PER_BYTE)
  37 #define BYTES_PER_GBIT          (GIGA / BITS_PER_BYTE)
  38
  39 #define ABSOLUTE_ZERO_MILLICELSIUS -273150
  40
  41 static inline long milli_kelvin_to_millicelsius(long t)
  42 {
  43         return t + ABSOLUTE_ZERO_MILLICELSIUS;
  44 }
  45
  46 static inline long millicelsius_to_milli_kelvin(long t)
  47 {
  48         return t - ABSOLUTE_ZERO_MILLICELSIUS;
  49 }
  50
  51 #define MILLIDEGREE_PER_DEGREE 1000
  52 #define MILLIDEGREE_PER_DECIDEGREE 100
  53
  54 static inline long kelvin_to_millicelsius(long t)
  55 {
  56         return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DEGREE);
  57 }
  58
  59 static inline long millicelsius_to_kelvin(long t)
  60 {
  61         t = millicelsius_to_milli_kelvin(t);
  62
  63         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
  64 }
  65
  66 static inline long deci_kelvin_to_celsius(long t)
  67 {
  68         t = milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
  69
  70         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
  71 }
  72
  73 static inline long celsius_to_deci_kelvin(long t)
  74 {
  75         t = millicelsius_to_milli_kelvin(t * MILLIDEGREE_PER_DEGREE);
  76
  77         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
  78 }
  79
  80 /**
  81  * deci_kelvin_to_millicelsius_with_offset - convert Kelvin to Celsius
  82  * @t: temperature value in decidegrees Kelvin
  83  * @offset: difference between Kelvin and Celsius in millidegrees
  84  *
  85  * Return: temperature value in millidegrees Celsius
  86  */
  87 static inline long deci_kelvin_to_millicelsius_with_offset(long t, long offset)
  88 {
  89         return t * MILLIDEGREE_PER_DECIDEGREE - offset;
  90 }
  91
  92 static inline long deci_kelvin_to_millicelsius(long t)
  93 {
  94         return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
  95 }
  96
  97 static inline long millicelsius_to_deci_kelvin(long t)
  98 {
  99         t = millicelsius_to_milli_kelvin(t);
 100
 101         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
 102 }
 103
 104 static inline long kelvin_to_celsius(long t)
 105 {
 106         return t + DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
 107                                      MILLIDEGREE_PER_DEGREE);
 108 }
 109
 110 static inline long celsius_to_kelvin(long t)
 111 {
 112         return t - DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
 113                                      MILLIDEGREE_PER_DEGREE);
 114 }
 115
 116 #endif /* _LINUX_UNITS_H */