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