LXR linux/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
  33static inline long milli_kelvin_to_millicelsius(long t)
  34{
  35        return t + ABSOLUTE_ZERO_MILLICELSIUS;
  36}
  37
  38static 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
  46static inline long kelvin_to_millicelsius(long t)
  47{
  48        return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DEGREE);
  49}
  50
  51static 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
  58static 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
  65static 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 */
  79static inline long deci_kelvin_to_millicelsius_with_offset(long t, long offset)
  80{
  81        return t * MILLIDEGREE_PER_DECIDEGREE - offset;
  82}
  83
  84static inline long deci_kelvin_to_millicelsius(long t)
  85{
  86        return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
  87}
  88
  89static 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
  96static inline long kelvin_to_celsius(long t)
  97{
  98        return t + DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
  99                                     MILLIDEGREE_PER_DEGREE);
 100}
 101
 102static 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 */
 109