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6082 | serge | 1 | /* |
2 | * linux/kernel/time.c |
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3 | * |
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4 | * Copyright (C) 1991, 1992 Linus Torvalds |
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5 | * |
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6 | * This file contains the interface functions for the various |
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7 | * time related system calls: time, stime, gettimeofday, settimeofday, |
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8 | * adjtime |
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9 | */ |
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10 | /* |
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11 | * Modification history kernel/time.c |
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12 | * |
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13 | * 1993-09-02 Philip Gladstone |
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14 | * Created file with time related functions from sched/core.c and adjtimex() |
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15 | * 1993-10-08 Torsten Duwe |
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16 | * adjtime interface update and CMOS clock write code |
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17 | * 1995-08-13 Torsten Duwe |
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18 | * kernel PLL updated to 1994-12-13 specs (rfc-1589) |
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19 | * 1999-01-16 Ulrich Windl |
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20 | * Introduced error checking for many cases in adjtimex(). |
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21 | * Updated NTP code according to technical memorandum Jan '96 |
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22 | * "A Kernel Model for Precision Timekeeping" by Dave Mills |
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23 | * Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10) |
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24 | * (Even though the technical memorandum forbids it) |
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25 | * 2004-07-14 Christoph Lameter |
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26 | * Added getnstimeofday to allow the posix timer functions to return |
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27 | * with nanosecond accuracy |
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28 | */ |
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29 | |||
5270 | serge | 30 | #include |
6082 | serge | 31 | #include |
32 | #include |
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3031 | serge | 33 | |
34 | |||
35 | |||
36 | #define HZ_TO_MSEC_MUL32 0xA0000000 |
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37 | #define HZ_TO_MSEC_ADJ32 0x0 |
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38 | #define HZ_TO_MSEC_SHR32 28 |
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39 | #define HZ_TO_MSEC_MUL64 0xA000000000000000 |
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40 | #define HZ_TO_MSEC_ADJ64 0x0 |
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41 | #define HZ_TO_MSEC_SHR64 60 |
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42 | #define MSEC_TO_HZ_MUL32 0xCCCCCCCD |
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43 | #define MSEC_TO_HZ_ADJ32 0x733333333 |
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44 | #define MSEC_TO_HZ_SHR32 35 |
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45 | #define MSEC_TO_HZ_MUL64 0xCCCCCCCCCCCCCCCD |
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46 | #define MSEC_TO_HZ_ADJ64 0x73333333333333333 |
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47 | #define MSEC_TO_HZ_SHR64 67 |
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48 | #define HZ_TO_MSEC_NUM 10 |
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49 | #define HZ_TO_MSEC_DEN 1 |
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50 | #define MSEC_TO_HZ_NUM 1 |
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51 | #define MSEC_TO_HZ_DEN 10 |
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52 | |||
53 | #define HZ_TO_USEC_MUL32 0x9C400000 |
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54 | #define HZ_TO_USEC_ADJ32 0x0 |
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55 | #define HZ_TO_USEC_SHR32 18 |
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56 | #define HZ_TO_USEC_MUL64 0x9C40000000000000 |
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57 | #define HZ_TO_USEC_ADJ64 0x0 |
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58 | #define HZ_TO_USEC_SHR64 50 |
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59 | #define USEC_TO_HZ_MUL32 0xD1B71759 |
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60 | #define USEC_TO_HZ_ADJ32 0x1FFF2E48E8A7 |
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61 | #define USEC_TO_HZ_SHR32 45 |
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62 | #define USEC_TO_HZ_MUL64 0xD1B71758E219652C |
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63 | #define USEC_TO_HZ_ADJ64 0x1FFF2E48E8A71DE69AD4 |
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64 | #define USEC_TO_HZ_SHR64 77 |
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65 | #define HZ_TO_USEC_NUM 10000 |
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66 | #define HZ_TO_USEC_DEN 1 |
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67 | #define USEC_TO_HZ_NUM 1 |
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68 | #define USEC_TO_HZ_DEN 10000 |
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69 | |||
70 | |||
71 | #define MSEC_PER_SEC 1000L |
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72 | #define USEC_PER_MSEC 1000L |
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73 | #define NSEC_PER_USEC 1000L |
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74 | #define NSEC_PER_MSEC 1000000L |
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75 | #define USEC_PER_SEC 1000000L |
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76 | #define NSEC_PER_SEC 1000000000L |
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77 | #define FSEC_PER_SEC 1000000000000000LL |
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78 | |||
6082 | serge | 79 | # define USER_HZ 100 |
80 | /* |
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81 | * Convert jiffies to milliseconds and back. |
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82 | * |
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83 | * Avoid unnecessary multiplications/divisions in the |
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84 | * two most common HZ cases: |
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85 | */ |
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3031 | serge | 86 | unsigned int jiffies_to_msecs(const unsigned long j) |
87 | { |
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88 | #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ) |
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6082 | serge | 89 | return (MSEC_PER_SEC / HZ) * j; |
3031 | serge | 90 | #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC) |
6082 | serge | 91 | return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC); |
3031 | serge | 92 | #else |
93 | # if BITS_PER_LONG == 32 |
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6082 | serge | 94 | return (HZ_TO_MSEC_MUL32 * j) >> HZ_TO_MSEC_SHR32; |
3031 | serge | 95 | # else |
6082 | serge | 96 | return (j * HZ_TO_MSEC_NUM) / HZ_TO_MSEC_DEN; |
3031 | serge | 97 | # endif |
98 | #endif |
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99 | } |
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6082 | serge | 100 | EXPORT_SYMBOL(jiffies_to_msecs); |
3031 | serge | 101 | |
102 | unsigned int jiffies_to_usecs(const unsigned long j) |
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103 | { |
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104 | #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ) |
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105 | return (USEC_PER_SEC / HZ) * j; |
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106 | #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC) |
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107 | return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC); |
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108 | #else |
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109 | # if BITS_PER_LONG == 32 |
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6082 | serge | 110 | return (HZ_TO_USEC_MUL32 * j) >> HZ_TO_USEC_SHR32; |
3031 | serge | 111 | # else |
6082 | serge | 112 | return (j * HZ_TO_USEC_NUM) / HZ_TO_USEC_DEN; |
3031 | serge | 113 | # endif |
114 | #endif |
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115 | } |
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6082 | serge | 116 | EXPORT_SYMBOL(jiffies_to_usecs); |
3031 | serge | 117 | |
6082 | serge | 118 | /** |
119 | * timespec_trunc - Truncate timespec to a granularity |
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120 | * @t: Timespec |
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121 | * @gran: Granularity in ns. |
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122 | * |
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123 | * Truncate a timespec to a granularity. Always rounds down. gran must |
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124 | * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns). |
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125 | */ |
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126 | struct timespec timespec_trunc(struct timespec t, unsigned gran) |
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127 | { |
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128 | /* Avoid division in the common cases 1 ns and 1 s. */ |
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129 | if (gran == 1) { |
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130 | /* nothing */ |
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131 | } else if (gran == NSEC_PER_SEC) { |
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132 | t.tv_nsec = 0; |
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133 | } else if (gran > 1 && gran < NSEC_PER_SEC) { |
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134 | t.tv_nsec -= t.tv_nsec % gran; |
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135 | } else { |
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136 | WARN(1, "illegal file time granularity: %u", gran); |
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137 | } |
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138 | return t; |
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139 | } |
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140 | EXPORT_SYMBOL(timespec_trunc); |
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3031 | serge | 141 | |
142 | /* |
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6082 | serge | 143 | * mktime64 - Converts date to seconds. |
144 | * Converts Gregorian date to seconds since 1970-01-01 00:00:00. |
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145 | * Assumes input in normal date format, i.e. 1980-12-31 23:59:59 |
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146 | * => year=1980, mon=12, day=31, hour=23, min=59, sec=59. |
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3031 | serge | 147 | * |
6082 | serge | 148 | * [For the Julian calendar (which was used in Russia before 1917, |
149 | * Britain & colonies before 1752, anywhere else before 1582, |
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150 | * and is still in use by some communities) leave out the |
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151 | * -year/100+year/400 terms, and add 10.] |
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3031 | serge | 152 | * |
6082 | serge | 153 | * This algorithm was first published by Gauss (I think). |
154 | */ |
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155 | time64_t mktime64(const unsigned int year0, const unsigned int mon0, |
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156 | const unsigned int day, const unsigned int hour, |
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157 | const unsigned int min, const unsigned int sec) |
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158 | { |
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159 | unsigned int mon = mon0, year = year0; |
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160 | |||
161 | /* 1..12 -> 11,12,1..10 */ |
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162 | if (0 >= (int) (mon -= 2)) { |
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163 | mon += 12; /* Puts Feb last since it has leap day */ |
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164 | year -= 1; |
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165 | } |
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166 | |||
167 | return ((((time64_t) |
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168 | (year/4 - year/100 + year/400 + 367*mon/12 + day) + |
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169 | year*365 - 719499 |
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170 | )*24 + hour /* now have hours */ |
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171 | )*60 + min /* now have minutes */ |
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172 | )*60 + sec; /* finally seconds */ |
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173 | } |
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174 | EXPORT_SYMBOL(mktime64); |
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175 | |||
176 | /** |
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177 | * set_normalized_timespec - set timespec sec and nsec parts and normalize |
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3031 | serge | 178 | * |
6082 | serge | 179 | * @ts: pointer to timespec variable to be set |
180 | * @sec: seconds to set |
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181 | * @nsec: nanoseconds to set |
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3031 | serge | 182 | * |
6082 | serge | 183 | * Set seconds and nanoseconds field of a timespec variable and |
184 | * normalize to the timespec storage format |
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185 | * |
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186 | * Note: The tv_nsec part is always in the range of |
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187 | * 0 <= tv_nsec < NSEC_PER_SEC |
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188 | * For negative values only the tv_sec field is negative ! |
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3031 | serge | 189 | */ |
6082 | serge | 190 | void set_normalized_timespec(struct timespec *ts, time_t sec, s64 nsec) |
3031 | serge | 191 | { |
6082 | serge | 192 | while (nsec >= NSEC_PER_SEC) { |
193 | /* |
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194 | * The following asm() prevents the compiler from |
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195 | * optimising this loop into a modulo operation. See |
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196 | * also __iter_div_u64_rem() in include/linux/time.h |
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197 | */ |
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198 | asm("" : "+rm"(nsec)); |
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199 | nsec -= NSEC_PER_SEC; |
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200 | ++sec; |
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201 | } |
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202 | while (nsec < 0) { |
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203 | asm("" : "+rm"(nsec)); |
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204 | nsec += NSEC_PER_SEC; |
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205 | --sec; |
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206 | } |
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207 | ts->tv_sec = sec; |
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208 | ts->tv_nsec = nsec; |
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209 | } |
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210 | EXPORT_SYMBOL(set_normalized_timespec); |
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3031 | serge | 211 | |
6082 | serge | 212 | /** |
213 | * ns_to_timespec - Convert nanoseconds to timespec |
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214 | * @nsec: the nanoseconds value to be converted |
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215 | * |
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216 | * Returns the timespec representation of the nsec parameter. |
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217 | */ |
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218 | struct timespec ns_to_timespec(const s64 nsec) |
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219 | { |
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220 | struct timespec ts; |
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221 | s32 rem; |
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3031 | serge | 222 | |
6082 | serge | 223 | if (!nsec) |
224 | return (struct timespec) {0, 0}; |
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3031 | serge | 225 | |
6082 | serge | 226 | ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem); |
227 | if (unlikely(rem < 0)) { |
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228 | ts.tv_sec--; |
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229 | rem += NSEC_PER_SEC; |
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230 | } |
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231 | ts.tv_nsec = rem; |
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232 | |||
233 | return ts; |
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3031 | serge | 234 | } |
6082 | serge | 235 | EXPORT_SYMBOL(ns_to_timespec); |
3031 | serge | 236 | |
6082 | serge | 237 | /** |
238 | * ns_to_timeval - Convert nanoseconds to timeval |
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239 | * @nsec: the nanoseconds value to be converted |
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240 | * |
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241 | * Returns the timeval representation of the nsec parameter. |
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242 | */ |
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243 | struct timeval ns_to_timeval(const s64 nsec) |
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3031 | serge | 244 | { |
6082 | serge | 245 | struct timespec ts = ns_to_timespec(nsec); |
246 | struct timeval tv; |
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247 | |||
248 | tv.tv_sec = ts.tv_sec; |
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249 | tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000; |
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250 | |||
251 | return tv; |
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252 | } |
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253 | EXPORT_SYMBOL(ns_to_timeval); |
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254 | |||
255 | #if BITS_PER_LONG == 32 |
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256 | /** |
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257 | * set_normalized_timespec - set timespec sec and nsec parts and normalize |
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258 | * |
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259 | * @ts: pointer to timespec variable to be set |
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260 | * @sec: seconds to set |
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261 | * @nsec: nanoseconds to set |
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262 | * |
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263 | * Set seconds and nanoseconds field of a timespec variable and |
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264 | * normalize to the timespec storage format |
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265 | * |
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266 | * Note: The tv_nsec part is always in the range of |
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267 | * 0 <= tv_nsec < NSEC_PER_SEC |
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268 | * For negative values only the tv_sec field is negative ! |
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269 | */ |
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270 | void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec) |
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271 | { |
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272 | while (nsec >= NSEC_PER_SEC) { |
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273 | /* |
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274 | * The following asm() prevents the compiler from |
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275 | * optimising this loop into a modulo operation. See |
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276 | * also __iter_div_u64_rem() in include/linux/time.h |
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277 | */ |
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278 | asm("" : "+rm"(nsec)); |
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279 | nsec -= NSEC_PER_SEC; |
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280 | ++sec; |
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281 | } |
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282 | while (nsec < 0) { |
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283 | asm("" : "+rm"(nsec)); |
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284 | nsec += NSEC_PER_SEC; |
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285 | --sec; |
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286 | } |
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287 | ts->tv_sec = sec; |
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288 | ts->tv_nsec = nsec; |
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289 | } |
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290 | EXPORT_SYMBOL(set_normalized_timespec64); |
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291 | |||
292 | /** |
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293 | * ns_to_timespec64 - Convert nanoseconds to timespec64 |
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294 | * @nsec: the nanoseconds value to be converted |
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295 | * |
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296 | * Returns the timespec64 representation of the nsec parameter. |
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297 | */ |
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298 | struct timespec64 ns_to_timespec64(const s64 nsec) |
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299 | { |
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300 | struct timespec64 ts; |
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301 | s32 rem; |
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302 | |||
303 | if (!nsec) |
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304 | return (struct timespec64) {0, 0}; |
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305 | |||
306 | ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem); |
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307 | if (unlikely(rem < 0)) { |
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308 | ts.tv_sec--; |
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309 | rem += NSEC_PER_SEC; |
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310 | } |
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311 | ts.tv_nsec = rem; |
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312 | |||
313 | return ts; |
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314 | } |
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315 | EXPORT_SYMBOL(ns_to_timespec64); |
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3031 | serge | 316 | #endif |
6082 | serge | 317 | /** |
318 | * msecs_to_jiffies: - convert milliseconds to jiffies |
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319 | * @m: time in milliseconds |
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320 | * |
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321 | * conversion is done as follows: |
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322 | * |
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323 | * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) |
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324 | * |
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325 | * - 'too large' values [that would result in larger than |
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326 | * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. |
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327 | * |
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328 | * - all other values are converted to jiffies by either multiplying |
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329 | * the input value by a factor or dividing it with a factor and |
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330 | * handling any 32-bit overflows. |
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331 | * for the details see __msecs_to_jiffies() |
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332 | * |
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333 | * msecs_to_jiffies() checks for the passed in value being a constant |
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334 | * via __builtin_constant_p() allowing gcc to eliminate most of the |
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335 | * code, __msecs_to_jiffies() is called if the value passed does not |
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336 | * allow constant folding and the actual conversion must be done at |
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337 | * runtime. |
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338 | * the _msecs_to_jiffies helpers are the HZ dependent conversion |
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339 | * routines found in include/linux/jiffies.h |
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340 | */ |
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341 | unsigned long __msecs_to_jiffies(const unsigned int m) |
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342 | { |
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343 | /* |
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344 | * Negative value, means infinite timeout: |
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345 | */ |
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346 | if ((int)m < 0) |
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347 | return MAX_JIFFY_OFFSET; |
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348 | return _msecs_to_jiffies(m); |
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3031 | serge | 349 | } |
6082 | serge | 350 | EXPORT_SYMBOL(__msecs_to_jiffies); |
3031 | serge | 351 | |
6082 | serge | 352 | unsigned long __usecs_to_jiffies(const unsigned int u) |
353 | { |
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354 | if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET)) |
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355 | return MAX_JIFFY_OFFSET; |
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356 | return _usecs_to_jiffies(u); |
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357 | } |
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358 | EXPORT_SYMBOL(__usecs_to_jiffies); |
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359 | |||
5270 | serge | 360 | /* |
361 | * The TICK_NSEC - 1 rounds up the value to the next resolution. Note |
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362 | * that a remainder subtract here would not do the right thing as the |
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363 | * resolution values don't fall on second boundries. I.e. the line: |
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364 | * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding. |
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365 | * Note that due to the small error in the multiplier here, this |
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366 | * rounding is incorrect for sufficiently large values of tv_nsec, but |
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367 | * well formed timespecs should have tv_nsec < NSEC_PER_SEC, so we're |
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368 | * OK. |
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369 | * |
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370 | * Rather, we just shift the bits off the right. |
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371 | * |
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372 | * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec |
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373 | * value to a scaled second value. |
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374 | */ |
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375 | static unsigned long |
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6082 | serge | 376 | __timespec64_to_jiffies(u64 sec, long nsec) |
3297 | Serge | 377 | { |
5270 | serge | 378 | nsec = nsec + TICK_NSEC - 1; |
3297 | Serge | 379 | |
6082 | serge | 380 | if (sec >= MAX_SEC_IN_JIFFIES){ |
381 | sec = MAX_SEC_IN_JIFFIES; |
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382 | nsec = 0; |
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383 | } |
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384 | return ((sec * SEC_CONVERSION) + |
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385 | (((u64)nsec * NSEC_CONVERSION) >> |
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386 | (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC; |
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3297 | Serge | 387 | |
388 | } |
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389 | |||
6082 | serge | 390 | static unsigned long |
391 | __timespec_to_jiffies(unsigned long sec, long nsec) |
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392 | { |
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393 | return __timespec64_to_jiffies((u64)sec, nsec); |
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394 | } |
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395 | |||
5270 | serge | 396 | unsigned long |
6082 | serge | 397 | timespec64_to_jiffies(const struct timespec64 *value) |
5270 | serge | 398 | { |
6082 | serge | 399 | return __timespec64_to_jiffies(value->tv_sec, value->tv_nsec); |
5270 | serge | 400 | } |
6082 | serge | 401 | EXPORT_SYMBOL(timespec64_to_jiffies); |
5270 | serge | 402 | |
403 | void |
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6082 | serge | 404 | jiffies_to_timespec64(const unsigned long jiffies, struct timespec64 *value) |
5270 | serge | 405 | { |
406 | /* |
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407 | * Convert jiffies to nanoseconds and separate with |
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408 | * one divide. |
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409 | */ |
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410 | u32 rem; |
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411 | value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC, |
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412 | NSEC_PER_SEC, &rem); |
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413 | value->tv_nsec = rem; |
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414 | } |
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6082 | serge | 415 | EXPORT_SYMBOL(jiffies_to_timespec64); |
5270 | serge | 416 | |
6082 | serge | 417 | /* |
418 | * We could use a similar algorithm to timespec_to_jiffies (with a |
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419 | * different multiplier for usec instead of nsec). But this has a |
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420 | * problem with rounding: we can't exactly add TICK_NSEC - 1 to the |
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421 | * usec value, since it's not necessarily integral. |
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422 | * |
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423 | * We could instead round in the intermediate scaled representation |
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424 | * (i.e. in units of 1/2^(large scale) jiffies) but that's also |
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425 | * perilous: the scaling introduces a small positive error, which |
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426 | * combined with a division-rounding-upward (i.e. adding 2^(scale) - 1 |
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427 | * units to the intermediate before shifting) leads to accidental |
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428 | * overflow and overestimates. |
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429 | * |
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430 | * At the cost of one additional multiplication by a constant, just |
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431 | * use the timespec implementation. |
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432 | */ |
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433 | unsigned long |
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434 | timeval_to_jiffies(const struct timeval *value) |
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435 | { |
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436 | return __timespec_to_jiffies(value->tv_sec, |
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437 | value->tv_usec * NSEC_PER_USEC); |
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438 | } |
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439 | EXPORT_SYMBOL(timeval_to_jiffies); |
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440 | |||
441 | void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value) |
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442 | { |
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443 | /* |
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444 | * Convert jiffies to nanoseconds and separate with |
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445 | * one divide. |
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446 | */ |
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447 | u32 rem; |
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448 | |||
449 | value->tv_sec = div_u64_rem((u64)jiffies * TICK_NSEC, |
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450 | NSEC_PER_SEC, &rem); |
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451 | value->tv_usec = rem / NSEC_PER_USEC; |
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452 | } |
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453 | EXPORT_SYMBOL(jiffies_to_timeval); |
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454 | |||
455 | /* |
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456 | * Convert jiffies/jiffies_64 to clock_t and back. |
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457 | */ |
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458 | clock_t jiffies_to_clock_t(unsigned long x) |
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459 | { |
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460 | #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 |
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461 | # if HZ < USER_HZ |
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462 | return x * (USER_HZ / HZ); |
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463 | # else |
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464 | return x / (HZ / USER_HZ); |
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465 | # endif |
||
466 | #else |
||
467 | return div_u64((u64)x * TICK_NSEC, NSEC_PER_SEC / USER_HZ); |
||
468 | #endif |
||
469 | } |
||
470 | EXPORT_SYMBOL(jiffies_to_clock_t); |
||
471 | |||
472 | unsigned long clock_t_to_jiffies(unsigned long x) |
||
473 | { |
||
474 | #if (HZ % USER_HZ)==0 |
||
475 | if (x >= ~0UL / (HZ / USER_HZ)) |
||
476 | return ~0UL; |
||
477 | return x * (HZ / USER_HZ); |
||
478 | #else |
||
479 | /* Don't worry about loss of precision here .. */ |
||
480 | if (x >= ~0UL / HZ * USER_HZ) |
||
481 | return ~0UL; |
||
482 | |||
483 | /* .. but do try to contain it here */ |
||
484 | return div_u64((u64)x * HZ, USER_HZ); |
||
485 | #endif |
||
486 | } |
||
487 | EXPORT_SYMBOL(clock_t_to_jiffies); |
||
488 | |||
489 | u64 jiffies_64_to_clock_t(u64 x) |
||
490 | { |
||
491 | #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0 |
||
492 | # if HZ < USER_HZ |
||
493 | x = div_u64(x * USER_HZ, HZ); |
||
494 | # elif HZ > USER_HZ |
||
495 | x = div_u64(x, HZ / USER_HZ); |
||
496 | # else |
||
497 | /* Nothing to do */ |
||
498 | # endif |
||
499 | #else |
||
500 | /* |
||
501 | * There are better ways that don't overflow early, |
||
502 | * but even this doesn't overflow in hundreds of years |
||
503 | * in 64 bits, so.. |
||
504 | */ |
||
505 | x = div_u64(x * TICK_NSEC, (NSEC_PER_SEC / USER_HZ)); |
||
506 | #endif |
||
507 | return x; |
||
508 | } |
||
509 | EXPORT_SYMBOL(jiffies_64_to_clock_t); |
||
510 | |||
511 | u64 nsec_to_clock_t(u64 x) |
||
512 | { |
||
513 | #if (NSEC_PER_SEC % USER_HZ) == 0 |
||
514 | return div_u64(x, NSEC_PER_SEC / USER_HZ); |
||
515 | #elif (USER_HZ % 512) == 0 |
||
516 | return div_u64(x * USER_HZ / 512, NSEC_PER_SEC / 512); |
||
517 | #else |
||
518 | /* |
||
519 | * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024, |
||
520 | * overflow after 64.99 years. |
||
521 | * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ... |
||
522 | */ |
||
523 | return div_u64(x * 9, (9ull * NSEC_PER_SEC + (USER_HZ / 2)) / USER_HZ); |
||
524 | #endif |
||
525 | } |
||
526 | |||
527 | /** |
||
528 | * nsecs_to_jiffies64 - Convert nsecs in u64 to jiffies64 |
||
529 | * |
||
530 | * @n: nsecs in u64 |
||
531 | * |
||
532 | * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64. |
||
533 | * And this doesn't return MAX_JIFFY_OFFSET since this function is designed |
||
534 | * for scheduler, not for use in device drivers to calculate timeout value. |
||
535 | * |
||
536 | * note: |
||
537 | * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512) |
||
538 | * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years |
||
539 | */ |
||
540 | u64 nsecs_to_jiffies64(u64 n) |
||
541 | { |
||
542 | #if (NSEC_PER_SEC % HZ) == 0 |
||
543 | /* Common case, HZ = 100, 128, 200, 250, 256, 500, 512, 1000 etc. */ |
||
544 | return div_u64(n, NSEC_PER_SEC / HZ); |
||
545 | #elif (HZ % 512) == 0 |
||
546 | /* overflow after 292 years if HZ = 1024 */ |
||
547 | return div_u64(n * HZ / 512, NSEC_PER_SEC / 512); |
||
548 | #else |
||
549 | /* |
||
550 | * Generic case - optimized for cases where HZ is a multiple of 3. |
||
551 | * overflow after 64.99 years, exact for HZ = 60, 72, 90, 120 etc. |
||
552 | */ |
||
553 | return div_u64(n * 9, (9ull * NSEC_PER_SEC + HZ / 2) / HZ); |
||
554 | #endif |
||
555 | } |
||
556 | EXPORT_SYMBOL(nsecs_to_jiffies64); |
||
557 | |||
558 | /** |
||
559 | * nsecs_to_jiffies - Convert nsecs in u64 to jiffies |
||
560 | * |
||
561 | * @n: nsecs in u64 |
||
562 | * |
||
563 | * Unlike {m,u}secs_to_jiffies, type of input is not unsigned int but u64. |
||
564 | * And this doesn't return MAX_JIFFY_OFFSET since this function is designed |
||
565 | * for scheduler, not for use in device drivers to calculate timeout value. |
||
566 | * |
||
567 | * note: |
||
568 | * NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512) |
||
569 | * ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years |
||
570 | */ |
||
571 | unsigned long nsecs_to_jiffies(u64 n) |
||
572 | { |
||
573 | return (unsigned long)nsecs_to_jiffies64(n); |
||
574 | } |
||
575 | EXPORT_SYMBOL_GPL(nsecs_to_jiffies); |
||
576 | |||
577 | /* |
||
578 | * Add two timespec values and do a safety check for overflow. |
||
579 | * It's assumed that both values are valid (>= 0) |
||
580 | */ |
||
581 | struct timespec timespec_add_safe(const struct timespec lhs, |
||
582 | const struct timespec rhs) |
||
583 | { |
||
584 | struct timespec res; |
||
585 | |||
586 | set_normalized_timespec(&res, lhs.tv_sec + rhs.tv_sec, |
||
587 | lhs.tv_nsec + rhs.tv_nsec); |
||
588 | |||
589 | if (res.tv_sec < lhs.tv_sec || res.tv_sec < rhs.tv_sec) |
||
590 | res.tv_sec = TIME_T_MAX; |
||
591 | |||
592 | return res; |
||
593 | } |
||
594 | |||
4244 | Serge | 595 | s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder) |
596 | { |
||
597 | u64 quotient; |
||
598 | |||
599 | if (dividend < 0) { |
||
600 | quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder); |
||
601 | *remainder = -*remainder; |
||
602 | if (divisor > 0) |
||
603 | quotient = -quotient; |
||
604 | } else { |
||
605 | quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder); |
||
606 | if (divisor < 0) |
||
607 | quotient = -quotient; |
||
608 | } |
||
609 | return quotient; |
||
610 | }>>>>=>>>>>>>>=>>>>=>>=>=> |
||
611 |