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6588 | serge | 1 | /* linux/include/linux/clocksource.h |
2 | * |
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3 | * This file contains the structure definitions for clocksources. |
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4 | * |
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5 | * If you are not a clocksource, or timekeeping code, you should |
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6 | * not be including this file! |
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7 | */ |
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8 | #ifndef _LINUX_CLOCKSOURCE_H |
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9 | #define _LINUX_CLOCKSOURCE_H |
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10 | |||
11 | #include |
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12 | #include |
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13 | #include |
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14 | #include |
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15 | #include |
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6934 | serge | 16 | #include |
6588 | serge | 17 | #include |
18 | #include |
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19 | #include |
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20 | |||
21 | struct clocksource; |
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22 | struct module; |
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23 | |||
24 | #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
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25 | #include |
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26 | #endif |
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27 | |||
28 | /** |
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29 | * struct clocksource - hardware abstraction for a free running counter |
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30 | * Provides mostly state-free accessors to the underlying hardware. |
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31 | * This is the structure used for system time. |
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32 | * |
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33 | * @name: ptr to clocksource name |
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34 | * @list: list head for registration |
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35 | * @rating: rating value for selection (higher is better) |
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36 | * To avoid rating inflation the following |
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37 | * list should give you a guide as to how |
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38 | * to assign your clocksource a rating |
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39 | * 1-99: Unfit for real use |
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40 | * Only available for bootup and testing purposes. |
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41 | * 100-199: Base level usability. |
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42 | * Functional for real use, but not desired. |
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43 | * 200-299: Good. |
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44 | * A correct and usable clocksource. |
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45 | * 300-399: Desired. |
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46 | * A reasonably fast and accurate clocksource. |
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47 | * 400-499: Perfect |
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48 | * The ideal clocksource. A must-use where |
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49 | * available. |
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50 | * @read: returns a cycle value, passes clocksource as argument |
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51 | * @enable: optional function to enable the clocksource |
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52 | * @disable: optional function to disable the clocksource |
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53 | * @mask: bitmask for two's complement |
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54 | * subtraction of non 64 bit counters |
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55 | * @mult: cycle to nanosecond multiplier |
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56 | * @shift: cycle to nanosecond divisor (power of two) |
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57 | * @max_idle_ns: max idle time permitted by the clocksource (nsecs) |
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58 | * @maxadj: maximum adjustment value to mult (~11%) |
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59 | * @max_cycles: maximum safe cycle value which won't overflow on multiplication |
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60 | * @flags: flags describing special properties |
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61 | * @archdata: arch-specific data |
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62 | * @suspend: suspend function for the clocksource, if necessary |
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63 | * @resume: resume function for the clocksource, if necessary |
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64 | * @owner: module reference, must be set by clocksource in modules |
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65 | */ |
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66 | struct clocksource { |
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67 | /* |
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68 | * Hotpath data, fits in a single cache line when the |
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69 | * clocksource itself is cacheline aligned. |
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70 | */ |
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71 | cycle_t (*read)(struct clocksource *cs); |
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72 | cycle_t mask; |
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73 | u32 mult; |
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74 | u32 shift; |
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75 | u64 max_idle_ns; |
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76 | u32 maxadj; |
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77 | #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
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78 | struct arch_clocksource_data archdata; |
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79 | #endif |
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80 | u64 max_cycles; |
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81 | const char *name; |
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82 | struct list_head list; |
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83 | int rating; |
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84 | int (*enable)(struct clocksource *cs); |
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85 | void (*disable)(struct clocksource *cs); |
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86 | unsigned long flags; |
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87 | void (*suspend)(struct clocksource *cs); |
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88 | void (*resume)(struct clocksource *cs); |
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89 | |||
90 | /* private: */ |
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91 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
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92 | /* Watchdog related data, used by the framework */ |
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93 | struct list_head wd_list; |
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94 | cycle_t cs_last; |
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95 | cycle_t wd_last; |
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96 | #endif |
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97 | struct module *owner; |
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98 | } ____cacheline_aligned; |
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99 | |||
100 | /* |
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101 | * Clock source flags bits:: |
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102 | */ |
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103 | #define CLOCK_SOURCE_IS_CONTINUOUS 0x01 |
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104 | #define CLOCK_SOURCE_MUST_VERIFY 0x02 |
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105 | |||
106 | #define CLOCK_SOURCE_WATCHDOG 0x10 |
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107 | #define CLOCK_SOURCE_VALID_FOR_HRES 0x20 |
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108 | #define CLOCK_SOURCE_UNSTABLE 0x40 |
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109 | #define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80 |
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110 | #define CLOCK_SOURCE_RESELECT 0x100 |
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111 | |||
112 | /* simplify initialization of mask field */ |
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113 | #define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1) |
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114 | |||
115 | /** |
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116 | * clocksource_khz2mult - calculates mult from khz and shift |
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117 | * @khz: Clocksource frequency in KHz |
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118 | * @shift_constant: Clocksource shift factor |
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119 | * |
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120 | * Helper functions that converts a khz counter frequency to a timsource |
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121 | * multiplier, given the clocksource shift value |
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122 | */ |
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123 | static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) |
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124 | { |
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125 | /* khz = cyc/(Million ns) |
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126 | * mult/2^shift = ns/cyc |
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127 | * mult = ns/cyc * 2^shift |
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128 | * mult = 1Million/khz * 2^shift |
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129 | * mult = 1000000 * 2^shift / khz |
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130 | * mult = (1000000< |
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131 | */ |
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132 | u64 tmp = ((u64)1000000) << shift_constant; |
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133 | |||
134 | tmp += khz/2; /* round for do_div */ |
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135 | do_div(tmp, khz); |
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136 | |||
137 | return (u32)tmp; |
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138 | } |
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139 | |||
140 | /** |
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141 | * clocksource_hz2mult - calculates mult from hz and shift |
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142 | * @hz: Clocksource frequency in Hz |
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143 | * @shift_constant: Clocksource shift factor |
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144 | * |
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145 | * Helper functions that converts a hz counter |
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146 | * frequency to a timsource multiplier, given the |
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147 | * clocksource shift value |
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148 | */ |
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149 | static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) |
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150 | { |
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151 | /* hz = cyc/(Billion ns) |
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152 | * mult/2^shift = ns/cyc |
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153 | * mult = ns/cyc * 2^shift |
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154 | * mult = 1Billion/hz * 2^shift |
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155 | * mult = 1000000000 * 2^shift / hz |
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156 | * mult = (1000000000< |
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157 | */ |
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158 | u64 tmp = ((u64)1000000000) << shift_constant; |
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159 | |||
160 | tmp += hz/2; /* round for do_div */ |
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161 | do_div(tmp, hz); |
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162 | |||
163 | return (u32)tmp; |
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164 | } |
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165 | |||
166 | /** |
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167 | * clocksource_cyc2ns - converts clocksource cycles to nanoseconds |
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168 | * @cycles: cycles |
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169 | * @mult: cycle to nanosecond multiplier |
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170 | * @shift: cycle to nanosecond divisor (power of two) |
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171 | * |
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172 | * Converts cycles to nanoseconds, using the given mult and shift. |
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173 | * |
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174 | * XXX - This could use some mult_lxl_ll() asm optimization |
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175 | */ |
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176 | static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift) |
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177 | { |
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178 | return ((u64) cycles * mult) >> shift; |
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179 | } |
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180 | |||
181 | |||
182 | extern int clocksource_unregister(struct clocksource*); |
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183 | extern void clocksource_touch_watchdog(void); |
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184 | extern void clocksource_change_rating(struct clocksource *cs, int rating); |
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185 | extern void clocksource_suspend(void); |
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186 | extern void clocksource_resume(void); |
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187 | extern struct clocksource * __init clocksource_default_clock(void); |
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188 | extern void clocksource_mark_unstable(struct clocksource *cs); |
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189 | |||
190 | extern u64 |
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191 | clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles); |
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192 | extern void |
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193 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); |
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194 | |||
195 | /* |
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196 | * Don't call __clocksource_register_scale directly, use |
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197 | * clocksource_register_hz/khz |
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198 | */ |
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199 | extern int |
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200 | __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); |
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201 | extern void |
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202 | __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq); |
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203 | |||
204 | /* |
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205 | * Don't call this unless you are a default clocksource |
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206 | * (AKA: jiffies) and absolutely have to. |
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207 | */ |
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208 | static inline int __clocksource_register(struct clocksource *cs) |
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209 | { |
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210 | return __clocksource_register_scale(cs, 1, 0); |
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211 | } |
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212 | |||
213 | static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) |
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214 | { |
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215 | return __clocksource_register_scale(cs, 1, hz); |
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216 | } |
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217 | |||
218 | static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) |
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219 | { |
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220 | return __clocksource_register_scale(cs, 1000, khz); |
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221 | } |
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222 | |||
223 | static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz) |
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224 | { |
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225 | __clocksource_update_freq_scale(cs, 1, hz); |
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226 | } |
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227 | |||
228 | static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz) |
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229 | { |
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230 | __clocksource_update_freq_scale(cs, 1000, khz); |
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231 | } |
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232 | |||
233 | |||
234 | extern int timekeeping_notify(struct clocksource *clock); |
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235 | |||
236 | extern cycle_t clocksource_mmio_readl_up(struct clocksource *); |
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237 | extern cycle_t clocksource_mmio_readl_down(struct clocksource *); |
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238 | extern cycle_t clocksource_mmio_readw_up(struct clocksource *); |
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239 | extern cycle_t clocksource_mmio_readw_down(struct clocksource *); |
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240 | |||
241 | extern int clocksource_mmio_init(void __iomem *, const char *, |
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242 | unsigned long, int, unsigned, cycle_t (*)(struct clocksource *)); |
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243 | |||
244 | extern int clocksource_i8253_init(void); |
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245 | |||
246 | #define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ |
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247 | OF_DECLARE_1(clksrc, name, compat, fn) |
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248 | |||
249 | #ifdef CONFIG_CLKSRC_PROBE |
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250 | extern void clocksource_probe(void); |
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251 | #else |
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252 | static inline void clocksource_probe(void) {} |
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253 | #endif |
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254 | |||
255 | #define CLOCKSOURCE_ACPI_DECLARE(name, table_id, fn) \ |
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256 | ACPI_DECLARE_PROBE_ENTRY(clksrc, name, table_id, 0, NULL, 0, fn) |
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257 | |||
258 | #endif /* _LINUX_CLOCKSOURCE_H */><> |