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