1 /* SPDX-License-Identifier: GPL-2.0 */
5 #include <linux/math.h>
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
18 #define MICRO 1000000UL
19 #define NANO 1000000000UL
20 #define PICO 1000000000000ULL
21 #define FEMTO 1000000000000000ULL
23 #define MILLIWATT_PER_WATT 1000L
24 #define MICROWATT_PER_MILLIWATT 1000L
25 #define MICROWATT_PER_WATT 1000000L
27 #define ABSOLUTE_ZERO_MILLICELSIUS -273150
29 static inline long milli_kelvin_to_millicelsius(long t)
31 return t + ABSOLUTE_ZERO_MILLICELSIUS;
34 static inline long millicelsius_to_milli_kelvin(long t)
36 return t - ABSOLUTE_ZERO_MILLICELSIUS;
39 #define MILLIDEGREE_PER_DEGREE 1000
40 #define MILLIDEGREE_PER_DECIDEGREE 100
42 static inline long kelvin_to_millicelsius(long t)
44 return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DEGREE);
47 static inline long millicelsius_to_kelvin(long t)
49 t = millicelsius_to_milli_kelvin(t);
51 return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
54 static inline long deci_kelvin_to_celsius(long t)
56 t = milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
58 return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
61 static inline long celsius_to_deci_kelvin(long t)
63 t = millicelsius_to_milli_kelvin(t * MILLIDEGREE_PER_DEGREE);
65 return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
69 * deci_kelvin_to_millicelsius_with_offset - convert Kelvin to Celsius
70 * @t: temperature value in decidegrees Kelvin
71 * @offset: difference between Kelvin and Celsius in millidegrees
73 * Return: temperature value in millidegrees Celsius
75 static inline long deci_kelvin_to_millicelsius_with_offset(long t, long offset)
77 return t * MILLIDEGREE_PER_DECIDEGREE - offset;
80 static inline long deci_kelvin_to_millicelsius(long t)
82 return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
85 static inline long millicelsius_to_deci_kelvin(long t)
87 t = millicelsius_to_milli_kelvin(t);
89 return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
92 static inline long kelvin_to_celsius(long t)
94 return t + DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
95 MILLIDEGREE_PER_DEGREE);
98 static inline long celsius_to_kelvin(long t)
100 return t - DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
101 MILLIDEGREE_PER_DEGREE);
104 #endif /* _LINUX_UNITS_H */