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 
milli_kelvin_to_millicelsius(long t)33 static inline long milli_kelvin_to_millicelsius(long t)
34 {
35 	return t + ABSOLUTE_ZERO_MILLICELSIUS;
36 }
37 
millicelsius_to_milli_kelvin(long t)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 
kelvin_to_millicelsius(long t)46 static inline long kelvin_to_millicelsius(long t)
47 {
48 	return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DEGREE);
49 }
50 
millicelsius_to_kelvin(long t)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 
deci_kelvin_to_celsius(long t)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 
celsius_to_deci_kelvin(long t)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  */
deci_kelvin_to_millicelsius_with_offset(long t,long offset)79 static inline long deci_kelvin_to_millicelsius_with_offset(long t, long offset)
80 {
81 	return t * MILLIDEGREE_PER_DECIDEGREE - offset;
82 }
83 
deci_kelvin_to_millicelsius(long t)84 static inline long deci_kelvin_to_millicelsius(long t)
85 {
86 	return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
87 }
88 
millicelsius_to_deci_kelvin(long t)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 
kelvin_to_celsius(long t)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 
celsius_to_kelvin(long t)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 */
109