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Rev | Author | Line No. | Line |
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2967 | Serge | 1 | #ifndef _LINUX_JIFFIES_H |
2 | #define _LINUX_JIFFIES_H |
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3 | |||
4103 | Serge | 4 | #include |
2967 | Serge | 5 | #include |
6 | #include |
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4103 | Serge | 7 | #include |
2967 | Serge | 8 | //#include |
9 | //#include |
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10 | |||
11 | |||
12 | #define HZ 100 |
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13 | #define CLOCK_TICK_RATE 1193182ul |
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14 | |||
15 | /* |
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16 | * The following defines establish the engineering parameters of the PLL |
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17 | * model. The HZ variable establishes the timer interrupt frequency, 100 Hz |
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18 | * for the SunOS kernel, 256 Hz for the Ultrix kernel and 1024 Hz for the |
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19 | * OSF/1 kernel. The SHIFT_HZ define expresses the same value as the |
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20 | * nearest power of two in order to avoid hardware multiply operations. |
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21 | */ |
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22 | #if HZ >= 12 && HZ < 24 |
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23 | # define SHIFT_HZ 4 |
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24 | #elif HZ >= 24 && HZ < 48 |
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25 | # define SHIFT_HZ 5 |
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26 | #elif HZ >= 48 && HZ < 96 |
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27 | # define SHIFT_HZ 6 |
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28 | #elif HZ >= 96 && HZ < 192 |
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29 | # define SHIFT_HZ 7 |
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30 | #elif HZ >= 192 && HZ < 384 |
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31 | # define SHIFT_HZ 8 |
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32 | #elif HZ >= 384 && HZ < 768 |
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33 | # define SHIFT_HZ 9 |
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34 | #elif HZ >= 768 && HZ < 1536 |
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35 | # define SHIFT_HZ 10 |
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36 | #elif HZ >= 1536 && HZ < 3072 |
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37 | # define SHIFT_HZ 11 |
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38 | #elif HZ >= 3072 && HZ < 6144 |
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39 | # define SHIFT_HZ 12 |
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40 | #elif HZ >= 6144 && HZ < 12288 |
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41 | # define SHIFT_HZ 13 |
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42 | #else |
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43 | # error Invalid value of HZ. |
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44 | #endif |
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45 | |||
46 | /* Suppose we want to divide two numbers NOM and DEN: NOM/DEN, then we can |
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47 | * improve accuracy by shifting LSH bits, hence calculating: |
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48 | * (NOM << LSH) / DEN |
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49 | * This however means trouble for large NOM, because (NOM << LSH) may no |
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50 | * longer fit in 32 bits. The following way of calculating this gives us |
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51 | * some slack, under the following conditions: |
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52 | * - (NOM / DEN) fits in (32 - LSH) bits. |
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53 | * - (NOM % DEN) fits in (32 - LSH) bits. |
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54 | */ |
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55 | #define SH_DIV(NOM,DEN,LSH) ( (((NOM) / (DEN)) << (LSH)) \ |
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56 | + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN)) |
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57 | |||
4103 | Serge | 58 | /* LATCH is used in the interval timer and ftape setup. */ |
59 | #define LATCH ((CLOCK_TICK_RATE + HZ/2) / HZ) /* For divider */ |
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2967 | Serge | 60 | |
4103 | Serge | 61 | extern int register_refined_jiffies(long clock_tick_rate); |
2967 | Serge | 62 | |
4103 | Serge | 63 | /* TICK_NSEC is the time between ticks in nsec assuming SHIFTED_HZ */ |
64 | #define TICK_NSEC ((NSEC_PER_SEC+HZ/2)/HZ) |
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65 | |||
2967 | Serge | 66 | /* TICK_USEC is the time between ticks in usec assuming fake USER_HZ */ |
67 | #define TICK_USEC ((1000000UL + USER_HZ/2) / USER_HZ) |
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68 | |||
4103 | Serge | 69 | /* some arch's have a small-data section that can be accessed register-relative |
70 | * but that can only take up to, say, 4-byte variables. jiffies being part of |
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71 | * an 8-byte variable may not be correctly accessed unless we force the issue |
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72 | */ |
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73 | #define __jiffy_data __attribute__((section(".data"))) |
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2967 | Serge | 74 | |
4103 | Serge | 75 | /* |
76 | * The 64-bit value is not atomic - you MUST NOT read it |
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77 | * without sampling the sequence number in jiffies_lock. |
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78 | * get_jiffies_64() will do this for you as appropriate. |
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2967 | Serge | 79 | static inline u64 get_jiffies_64(void) |
80 | { |
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3031 | serge | 81 | return (u64)GetTimerTicks(); |
2967 | Serge | 82 | } |
83 | |||
84 | /* |
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85 | * These inlines deal with timer wrapping correctly. You are |
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86 | * strongly encouraged to use them |
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87 | * 1. Because people otherwise forget |
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88 | * 2. Because if the timer wrap changes in future you won't have to |
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89 | * alter your driver code. |
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90 | * |
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91 | * time_after(a,b) returns true if the time a is after time b. |
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92 | * |
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93 | * Do this with "<0" and ">=0" to only test the sign of the result. A |
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94 | * good compiler would generate better code (and a really good compiler |
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95 | * wouldn't care). Gcc is currently neither. |
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96 | */ |
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97 | #define time_after(a,b) \ |
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98 | (typecheck(unsigned long, a) && \ |
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99 | typecheck(unsigned long, b) && \ |
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4103 | Serge | 100 | ((long)((b) - (a)) < 0)) |
2967 | Serge | 101 | #define time_before(a,b) time_after(b,a) |
102 | |||
103 | #define time_after_eq(a,b) \ |
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104 | (typecheck(unsigned long, a) && \ |
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105 | typecheck(unsigned long, b) && \ |
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4103 | Serge | 106 | ((long)((a) - (b)) >= 0)) |
2967 | Serge | 107 | #define time_before_eq(a,b) time_after_eq(b,a) |
108 | |||
109 | /* |
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110 | * Calculate whether a is in the range of [b, c]. |
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111 | */ |
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112 | #define time_in_range(a,b,c) \ |
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113 | (time_after_eq(a,b) && \ |
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114 | time_before_eq(a,c)) |
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115 | |||
116 | /* |
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117 | * Calculate whether a is in the range of [b, c). |
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118 | */ |
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119 | #define time_in_range_open(a,b,c) \ |
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120 | (time_after_eq(a,b) && \ |
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121 | time_before(a,c)) |
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122 | |||
123 | /* Same as above, but does so with platform independent 64bit types. |
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124 | * These must be used when utilizing jiffies_64 (i.e. return value of |
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125 | * get_jiffies_64() */ |
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126 | #define time_after64(a,b) \ |
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127 | (typecheck(__u64, a) && \ |
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128 | typecheck(__u64, b) && \ |
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4103 | Serge | 129 | ((__s64)((b) - (a)) < 0)) |
2967 | Serge | 130 | #define time_before64(a,b) time_after64(b,a) |
131 | |||
132 | #define time_after_eq64(a,b) \ |
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133 | (typecheck(__u64, a) && \ |
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134 | typecheck(__u64, b) && \ |
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4103 | Serge | 135 | ((__s64)((a) - (b)) >= 0)) |
2967 | Serge | 136 | #define time_before_eq64(a,b) time_after_eq64(b,a) |
137 | |||
4065 | Serge | 138 | #define time_in_range64(a, b, c) \ |
139 | (time_after_eq64(a, b) && \ |
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140 | time_before_eq64(a, c)) |
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141 | |||
2967 | Serge | 142 | /* |
143 | * These four macros compare jiffies and 'a' for convenience. |
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144 | */ |
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145 | |||
146 | /* time_is_before_jiffies(a) return true if a is before jiffies */ |
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147 | #define time_is_before_jiffies(a) time_after(jiffies, a) |
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148 | |||
149 | /* time_is_after_jiffies(a) return true if a is after jiffies */ |
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150 | #define time_is_after_jiffies(a) time_before(jiffies, a) |
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151 | |||
152 | /* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/ |
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153 | #define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a) |
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154 | |||
155 | /* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/ |
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156 | #define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a) |
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157 | |||
158 | /* |
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159 | * Have the 32 bit jiffies value wrap 5 minutes after boot |
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160 | * so jiffies wrap bugs show up earlier. |
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161 | */ |
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162 | #define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ)) |
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163 | |||
164 | /* |
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165 | * Change timeval to jiffies, trying to avoid the |
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166 | * most obvious overflows.. |
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167 | * |
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168 | * And some not so obvious. |
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169 | * |
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170 | * Note that we don't want to return LONG_MAX, because |
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171 | * for various timeout reasons we often end up having |
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172 | * to wait "jiffies+1" in order to guarantee that we wait |
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173 | * at _least_ "jiffies" - so "jiffies+1" had better still |
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174 | * be positive. |
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175 | */ |
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176 | #define MAX_JIFFY_OFFSET ((LONG_MAX >> 1)-1) |
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177 | |||
178 | extern unsigned long preset_lpj; |
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179 | |||
180 | /* |
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181 | * We want to do realistic conversions of time so we need to use the same |
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182 | * values the update wall clock code uses as the jiffies size. This value |
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183 | * is: TICK_NSEC (which is defined in timex.h). This |
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184 | * is a constant and is in nanoseconds. We will use scaled math |
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185 | * with a set of scales defined here as SEC_JIFFIE_SC, USEC_JIFFIE_SC and |
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186 | * NSEC_JIFFIE_SC. Note that these defines contain nothing but |
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187 | * constants and so are computed at compile time. SHIFT_HZ (computed in |
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188 | * timex.h) adjusts the scaling for different HZ values. |
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189 | |||
190 | * Scaled math??? What is that? |
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191 | * |
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192 | * Scaled math is a way to do integer math on values that would, |
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193 | * otherwise, either overflow, underflow, or cause undesired div |
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194 | * instructions to appear in the execution path. In short, we "scale" |
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195 | * up the operands so they take more bits (more precision, less |
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196 | * underflow), do the desired operation and then "scale" the result back |
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197 | * by the same amount. If we do the scaling by shifting we avoid the |
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198 | * costly mpy and the dastardly div instructions. |
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199 | |||
200 | * Suppose, for example, we want to convert from seconds to jiffies |
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201 | * where jiffies is defined in nanoseconds as NSEC_PER_JIFFIE. The |
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202 | * simple math is: jiff = (sec * NSEC_PER_SEC) / NSEC_PER_JIFFIE; We |
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203 | * observe that (NSEC_PER_SEC / NSEC_PER_JIFFIE) is a constant which we |
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204 | * might calculate at compile time, however, the result will only have |
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205 | * about 3-4 bits of precision (less for smaller values of HZ). |
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206 | * |
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207 | * So, we scale as follows: |
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208 | * jiff = (sec) * (NSEC_PER_SEC / NSEC_PER_JIFFIE); |
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209 | * jiff = ((sec) * ((NSEC_PER_SEC * SCALE)/ NSEC_PER_JIFFIE)) / SCALE; |
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210 | * Then we make SCALE a power of two so: |
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211 | * jiff = ((sec) * ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) >> SCALE; |
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212 | * Now we define: |
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213 | * #define SEC_CONV = ((NSEC_PER_SEC << SCALE)/ NSEC_PER_JIFFIE)) |
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214 | * jiff = (sec * SEC_CONV) >> SCALE; |
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215 | * |
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216 | * Often the math we use will expand beyond 32-bits so we tell C how to |
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217 | * do this and pass the 64-bit result of the mpy through the ">> SCALE" |
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218 | * which should take the result back to 32-bits. We want this expansion |
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219 | * to capture as much precision as possible. At the same time we don't |
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220 | * want to overflow so we pick the SCALE to avoid this. In this file, |
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221 | * that means using a different scale for each range of HZ values (as |
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222 | * defined in timex.h). |
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223 | * |
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224 | * For those who want to know, gcc will give a 64-bit result from a "*" |
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225 | * operator if the result is a long long AND at least one of the |
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226 | * operands is cast to long long (usually just prior to the "*" so as |
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227 | * not to confuse it into thinking it really has a 64-bit operand, |
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228 | * which, buy the way, it can do, but it takes more code and at least 2 |
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229 | * mpys). |
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230 | |||
231 | * We also need to be aware that one second in nanoseconds is only a |
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232 | * couple of bits away from overflowing a 32-bit word, so we MUST use |
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233 | * 64-bits to get the full range time in nanoseconds. |
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234 | |||
235 | */ |
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236 | |||
237 | /* |
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238 | * Here are the scales we will use. One for seconds, nanoseconds and |
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239 | * microseconds. |
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240 | * |
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241 | * Within the limits of cpp we do a rough cut at the SEC_JIFFIE_SC and |
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242 | * check if the sign bit is set. If not, we bump the shift count by 1. |
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243 | * (Gets an extra bit of precision where we can use it.) |
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244 | * We know it is set for HZ = 1024 and HZ = 100 not for 1000. |
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245 | * Haven't tested others. |
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246 | |||
247 | * Limits of cpp (for #if expressions) only long (no long long), but |
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248 | * then we only need the most signicant bit. |
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249 | */ |
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250 | |||
251 | #define SEC_JIFFIE_SC (31 - SHIFT_HZ) |
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252 | #if !((((NSEC_PER_SEC << 2) / TICK_NSEC) << (SEC_JIFFIE_SC - 2)) & 0x80000000) |
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253 | #undef SEC_JIFFIE_SC |
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254 | #define SEC_JIFFIE_SC (32 - SHIFT_HZ) |
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255 | #endif |
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256 | #define NSEC_JIFFIE_SC (SEC_JIFFIE_SC + 29) |
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257 | #define USEC_JIFFIE_SC (SEC_JIFFIE_SC + 19) |
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258 | #define SEC_CONVERSION ((unsigned long)((((u64)NSEC_PER_SEC << SEC_JIFFIE_SC) +\ |
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259 | TICK_NSEC -1) / (u64)TICK_NSEC)) |
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260 | |||
261 | #define NSEC_CONVERSION ((unsigned long)((((u64)1 << NSEC_JIFFIE_SC) +\ |
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262 | TICK_NSEC -1) / (u64)TICK_NSEC)) |
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263 | #define USEC_CONVERSION \ |
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264 | ((unsigned long)((((u64)NSEC_PER_USEC << USEC_JIFFIE_SC) +\ |
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265 | TICK_NSEC -1) / (u64)TICK_NSEC)) |
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266 | /* |
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267 | * USEC_ROUND is used in the timeval to jiffie conversion. See there |
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268 | * for more details. It is the scaled resolution rounding value. Note |
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269 | * that it is a 64-bit value. Since, when it is applied, we are already |
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270 | * in jiffies (albit scaled), it is nothing but the bits we will shift |
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271 | * off. |
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272 | */ |
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273 | #define USEC_ROUND (u64)(((u64)1 << USEC_JIFFIE_SC) - 1) |
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274 | /* |
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275 | * The maximum jiffie value is (MAX_INT >> 1). Here we translate that |
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276 | * into seconds. The 64-bit case will overflow if we are not careful, |
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277 | * so use the messy SH_DIV macro to do it. Still all constants. |
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278 | */ |
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279 | #if BITS_PER_LONG < 64 |
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280 | # define MAX_SEC_IN_JIFFIES \ |
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281 | (long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC) |
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282 | #else /* take care of overflow on 64 bits machines */ |
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283 | # define MAX_SEC_IN_JIFFIES \ |
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284 | (SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1) |
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285 | |||
286 | #endif |
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287 | |||
288 | /* |
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289 | * Convert various time units to each other: |
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290 | */ |
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291 | extern unsigned int jiffies_to_msecs(const unsigned long j); |
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292 | extern unsigned int jiffies_to_usecs(const unsigned long j); |
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293 | extern unsigned long msecs_to_jiffies(const unsigned int m); |
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294 | extern unsigned long usecs_to_jiffies(const unsigned int u); |
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295 | extern unsigned long timespec_to_jiffies(const struct timespec *value); |
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296 | extern void jiffies_to_timespec(const unsigned long jiffies, |
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297 | struct timespec *value); |
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298 | extern unsigned long timeval_to_jiffies(const struct timeval *value); |
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299 | extern void jiffies_to_timeval(const unsigned long jiffies, |
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300 | struct timeval *value); |
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3031 | serge | 301 | |
2967 | Serge | 302 | extern clock_t jiffies_to_clock_t(unsigned long x); |
3031 | serge | 303 | static inline clock_t jiffies_delta_to_clock_t(long delta) |
304 | { |
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305 | return jiffies_to_clock_t(max(0L, delta)); |
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306 | } |
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307 | |||
2967 | Serge | 308 | extern unsigned long clock_t_to_jiffies(unsigned long x); |
309 | extern u64 jiffies_64_to_clock_t(u64 x); |
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310 | extern u64 nsec_to_clock_t(u64 x); |
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311 | extern u64 nsecs_to_jiffies64(u64 n); |
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312 | extern unsigned long nsecs_to_jiffies(u64 n); |
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313 | |||
3482 | Serge | 314 | |
315 | static unsigned long round_jiffies_common(unsigned long j, bool force_up) |
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316 | { |
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317 | int rem; |
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318 | unsigned long original = j; |
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319 | |||
320 | rem = j % HZ; |
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321 | |||
322 | /* |
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323 | * If the target jiffie is just after a whole second (which can happen |
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324 | * due to delays of the timer irq, long irq off times etc etc) then |
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325 | * we should round down to the whole second, not up. Use 1/4th second |
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326 | * as cutoff for this rounding as an extreme upper bound for this. |
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327 | * But never round down if @force_up is set. |
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328 | */ |
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329 | if (rem < HZ/4 && !force_up) /* round down */ |
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330 | j = j - rem; |
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331 | else /* round up */ |
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332 | j = j - rem + HZ; |
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333 | |||
334 | if (j <= GetTimerTicks()) /* rounding ate our timeout entirely; */ |
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335 | return original; |
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336 | return j; |
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337 | } |
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338 | |||
339 | |||
340 | |||
341 | unsigned long round_jiffies_up_relative(unsigned long j); |
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342 | |||
2967 | Serge | 343 | #define TIMESTAMP_SIZE 30 |
344 | |||
345 | #endif=>>>><>><>><>><>><>><>><>><>>>0">><>><>><>><>>>>>>>>>>> |