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 NANOHZ_PER_HZ		1000000000UL
24 #define MICROHZ_PER_HZ		1000000UL
25 #define MILLIHZ_PER_HZ		1000UL
26 #define HZ_PER_KHZ		1000UL
27 #define KHZ_PER_MHZ		1000UL
28 #define HZ_PER_MHZ		1000000UL
29 
30 #define MILLIWATT_PER_WATT	1000UL
31 #define MICROWATT_PER_MILLIWATT	1000UL
32 #define MICROWATT_PER_WATT	1000000UL
33 
34 #define ABSOLUTE_ZERO_MILLICELSIUS -273150
35 
milli_kelvin_to_millicelsius(long t)36 static inline long milli_kelvin_to_millicelsius(long t)
37 {
38 	return t + ABSOLUTE_ZERO_MILLICELSIUS;
39 }
40 
millicelsius_to_milli_kelvin(long t)41 static inline long millicelsius_to_milli_kelvin(long t)
42 {
43 	return t - ABSOLUTE_ZERO_MILLICELSIUS;
44 }
45 
46 #define MILLIDEGREE_PER_DEGREE 1000
47 #define MILLIDEGREE_PER_DECIDEGREE 100
48 
kelvin_to_millicelsius(long t)49 static inline long kelvin_to_millicelsius(long t)
50 {
51 	return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DEGREE);
52 }
53 
millicelsius_to_kelvin(long t)54 static inline long millicelsius_to_kelvin(long t)
55 {
56 	t = millicelsius_to_milli_kelvin(t);
57 
58 	return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
59 }
60 
deci_kelvin_to_celsius(long t)61 static inline long deci_kelvin_to_celsius(long t)
62 {
63 	t = milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
64 
65 	return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DEGREE);
66 }
67 
celsius_to_deci_kelvin(long t)68 static inline long celsius_to_deci_kelvin(long t)
69 {
70 	t = millicelsius_to_milli_kelvin(t * MILLIDEGREE_PER_DEGREE);
71 
72 	return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
73 }
74 
75 /**
76  * deci_kelvin_to_millicelsius_with_offset - convert Kelvin to Celsius
77  * @t: temperature value in decidegrees Kelvin
78  * @offset: difference between Kelvin and Celsius in millidegrees
79  *
80  * Return: temperature value in millidegrees Celsius
81  */
deci_kelvin_to_millicelsius_with_offset(long t,long offset)82 static inline long deci_kelvin_to_millicelsius_with_offset(long t, long offset)
83 {
84 	return t * MILLIDEGREE_PER_DECIDEGREE - offset;
85 }
86 
deci_kelvin_to_millicelsius(long t)87 static inline long deci_kelvin_to_millicelsius(long t)
88 {
89 	return milli_kelvin_to_millicelsius(t * MILLIDEGREE_PER_DECIDEGREE);
90 }
91 
millicelsius_to_deci_kelvin(long t)92 static inline long millicelsius_to_deci_kelvin(long t)
93 {
94 	t = millicelsius_to_milli_kelvin(t);
95 
96 	return DIV_ROUND_CLOSEST(t, MILLIDEGREE_PER_DECIDEGREE);
97 }
98 
kelvin_to_celsius(long t)99 static inline long kelvin_to_celsius(long t)
100 {
101 	return t + DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
102 				     MILLIDEGREE_PER_DEGREE);
103 }
104 
celsius_to_kelvin(long t)105 static inline long celsius_to_kelvin(long t)
106 {
107 	return t - DIV_ROUND_CLOSEST(ABSOLUTE_ZERO_MILLICELSIUS,
108 				     MILLIDEGREE_PER_DEGREE);
109 }
110 
111 #endif /* _LINUX_UNITS_H */
112