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/kernel.h>
   6
   7 #define ABSOLUTE_ZERO_MILLICELSIUS -273150
   8
   9 static inline long milli_kelvin_to_millicelsius(long t)
  10 {
  11         return t + ABSOLUTE_ZERO_MILLICELSIUS;
  12 }
  13
  14 static inline long millicelsius_to_milli_kelvin(long t)
  15 {
  16         return t - ABSOLUTE_ZERO_MILLICELSIUS;
  17 }
  18
  19 #define MILLIDEGREE_PER_DEGREE 1000
  20 #define MILLIDEGREE_PER_DECIDEGREE 100
  21
  22 static inline long kelvin_to_millicelsius(long t)
  23 {
  24         return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DEGREE);
  25 }
  26
  27 static inline long millicelsius_to_kelvin(long t)
  28 {
  29         t = millicelsius_to_milli_kelvin(t);
  30
  31         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
  32 }
  33
  34 static inline long deci_kelvin_to_celsius(long t)
  35 {
  36         t = milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
  37
  38         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
  39 }
  40
  41 static inline long celsius_to_deci_kelvin(long t)
  42 {
  43         t = millicelsius_to_milli_kelvin(t * MILLIDEGREE_PER_DEGREE);
  44
  45         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
  46 }
  47
  48 /**
  49  * deci_kelvin_to_millicelsius_with_offset - convert Kelvin to Celsius
  50  * @t: temperature value in decidegrees Kelvin
  51  * @offset: difference between Kelvin and Celsius in millidegrees
  52  *
  53  * Return: temperature value in millidegrees Celsius
  54  */
  55 static inline long deci_kelvin_to_millicelsius_with_offset(long t, long offset)
  56 {
  57         return t * MILLIDEGREE_PER_DECIDEGREE - offset;
  58 }
  59
  60 static inline long deci_kelvin_to_millicelsius(long t)
  61 {
  62         return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
  63 }
  64
  65 static inline long millicelsius_to_deci_kelvin(long t)
  66 {
  67         t = millicelsius_to_milli_kelvin(t);
  68
  69         return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
  70 }
  71
  72 static inline long kelvin_to_celsius(long t)
  73 {
  74         return t + DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
  75                                      MILLIDEGREE_PER_DEGREE);
  76 }
  77
  78 static inline long celsius_to_kelvin(long t)
  79 {
  80         return t - DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
  81                                      MILLIDEGREE_PER_DEGREE);
  82 }
  83
  84 #endif /* _LINUX_UNITS_H */