| 1 | /* linux/include/linux/clocksource.h |
| 2 | * |
| 3 | * This file contains the structure definitions for clocksources. |
| 4 | * |
| 5 | * If you are not a clocksource, or timekeeping code, you should |
| 6 | * not be including this file! |
| 7 | */ |
| 8 | #ifndef _LINUX_CLOCKSOURCE_H |
| 9 | #define _LINUX_CLOCKSOURCE_H |
| 10 | |
| 11 | #include <linux/types.h> |
| 12 | #include <linux/timex.h> |
| 13 | #include <linux/time.h> |
| 14 | #include <linux/list.h> |
| 15 | #include <linux/cache.h> |
| 16 | #include <linux/timer.h> |
| 17 | #include <linux/init.h> |
| 18 | #include <asm/div64.h> |
| 19 | #include <asm/io.h> |
| 20 | |
| 21 | struct clocksource; |
| 22 | struct module; |
| 23 | |
| 24 | #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
| 25 | #include <asm/clocksource.h> |
| 26 | #endif |
| 27 | |
| 28 | /** |
| 29 | * struct clocksource - hardware abstraction for a free running counter |
| 30 | * Provides mostly state-free accessors to the underlying hardware. |
| 31 | * This is the structure used for system time. |
| 32 | * |
| 33 | * @name: ptr to clocksource name |
| 34 | * @list: list head for registration |
| 35 | * @rating: rating value for selection (higher is better) |
| 36 | * To avoid rating inflation the following |
| 37 | * list should give you a guide as to how |
| 38 | * to assign your clocksource a rating |
| 39 | * 1-99: Unfit for real use |
| 40 | * Only available for bootup and testing purposes. |
| 41 | * 100-199: Base level usability. |
| 42 | * Functional for real use, but not desired. |
| 43 | * 200-299: Good. |
| 44 | * A correct and usable clocksource. |
| 45 | * 300-399: Desired. |
| 46 | * A reasonably fast and accurate clocksource. |
| 47 | * 400-499: Perfect |
| 48 | * The ideal clocksource. A must-use where |
| 49 | * available. |
| 50 | * @read: returns a cycle value, passes clocksource as argument |
| 51 | * @enable: optional function to enable the clocksource |
| 52 | * @disable: optional function to disable the clocksource |
| 53 | * @mask: bitmask for two's complement |
| 54 | * subtraction of non 64 bit counters |
| 55 | * @mult: cycle to nanosecond multiplier |
| 56 | * @shift: cycle to nanosecond divisor (power of two) |
| 57 | * @max_idle_ns: max idle time permitted by the clocksource (nsecs) |
| 58 | * @maxadj: maximum adjustment value to mult (~11%) |
| 59 | * @max_cycles: maximum safe cycle value which won't overflow on multiplication |
| 60 | * @flags: flags describing special properties |
| 61 | * @archdata: arch-specific data |
| 62 | * @suspend: suspend function for the clocksource, if necessary |
| 63 | * @resume: resume function for the clocksource, if necessary |
| 64 | * @owner: module reference, must be set by clocksource in modules |
| 65 | * |
| 66 | * Note: This struct is not used in hotpathes of the timekeeping code |
| 67 | * because the timekeeper caches the hot path fields in its own data |
| 68 | * structure, so no line cache alignment is required, |
| 69 | * |
| 70 | * The pointer to the clocksource itself is handed to the read |
| 71 | * callback. If you need extra information there you can wrap struct |
| 72 | * clocksource into your own struct. Depending on the amount of |
| 73 | * information you need you should consider to cache line align that |
| 74 | * structure. |
| 75 | */ |
| 76 | struct clocksource { |
| 77 | cycle_t (*read)(struct clocksource *cs); |
| 78 | cycle_t mask; |
| 79 | u32 mult; |
| 80 | u32 shift; |
| 81 | u64 max_idle_ns; |
| 82 | u32 maxadj; |
| 83 | #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
| 84 | struct arch_clocksource_data archdata; |
| 85 | #endif |
| 86 | u64 max_cycles; |
| 87 | const char *name; |
| 88 | struct list_head list; |
| 89 | int rating; |
| 90 | int (*enable)(struct clocksource *cs); |
| 91 | void (*disable)(struct clocksource *cs); |
| 92 | unsigned long flags; |
| 93 | void (*suspend)(struct clocksource *cs); |
| 94 | void (*resume)(struct clocksource *cs); |
| 95 | |
| 96 | /* private: */ |
| 97 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
| 98 | /* Watchdog related data, used by the framework */ |
| 99 | struct list_head wd_list; |
| 100 | cycle_t cs_last; |
| 101 | cycle_t wd_last; |
| 102 | #endif |
| 103 | struct module *owner; |
| 104 | }; |
| 105 | |
| 106 | /* |
| 107 | * Clock source flags bits:: |
| 108 | */ |
| 109 | #define CLOCK_SOURCE_IS_CONTINUOUS 0x01 |
| 110 | #define CLOCK_SOURCE_MUST_VERIFY 0x02 |
| 111 | |
| 112 | #define CLOCK_SOURCE_WATCHDOG 0x10 |
| 113 | #define CLOCK_SOURCE_VALID_FOR_HRES 0x20 |
| 114 | #define CLOCK_SOURCE_UNSTABLE 0x40 |
| 115 | #define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80 |
| 116 | #define CLOCK_SOURCE_RESELECT 0x100 |
| 117 | |
| 118 | /* simplify initialization of mask field */ |
| 119 | #define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1) |
| 120 | |
| 121 | static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from) |
| 122 | { |
| 123 | /* freq = cyc/from |
| 124 | * mult/2^shift = ns/cyc |
| 125 | * mult = ns/cyc * 2^shift |
| 126 | * mult = from/freq * 2^shift |
| 127 | * mult = from * 2^shift / freq |
| 128 | * mult = (from<<shift) / freq |
| 129 | */ |
| 130 | u64 tmp = ((u64)from) << shift_constant; |
| 131 | |
| 132 | tmp += freq/2; /* round for do_div */ |
| 133 | do_div(tmp, freq); |
| 134 | |
| 135 | return (u32)tmp; |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * clocksource_khz2mult - calculates mult from khz and shift |
| 140 | * @khz: Clocksource frequency in KHz |
| 141 | * @shift_constant: Clocksource shift factor |
| 142 | * |
| 143 | * Helper functions that converts a khz counter frequency to a timsource |
| 144 | * multiplier, given the clocksource shift value |
| 145 | */ |
| 146 | static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) |
| 147 | { |
| 148 | return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC); |
| 149 | } |
| 150 | |
| 151 | /** |
| 152 | * clocksource_hz2mult - calculates mult from hz and shift |
| 153 | * @hz: Clocksource frequency in Hz |
| 154 | * @shift_constant: Clocksource shift factor |
| 155 | * |
| 156 | * Helper functions that converts a hz counter |
| 157 | * frequency to a timsource multiplier, given the |
| 158 | * clocksource shift value |
| 159 | */ |
| 160 | static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) |
| 161 | { |
| 162 | return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC); |
| 163 | } |
| 164 | |
| 165 | /** |
| 166 | * clocksource_cyc2ns - converts clocksource cycles to nanoseconds |
| 167 | * @cycles: cycles |
| 168 | * @mult: cycle to nanosecond multiplier |
| 169 | * @shift: cycle to nanosecond divisor (power of two) |
| 170 | * |
| 171 | * Converts cycles to nanoseconds, using the given mult and shift. |
| 172 | * |
| 173 | * XXX - This could use some mult_lxl_ll() asm optimization |
| 174 | */ |
| 175 | static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift) |
| 176 | { |
| 177 | return ((u64) cycles * mult) >> shift; |
| 178 | } |
| 179 | |
| 180 | |
| 181 | extern int clocksource_unregister(struct clocksource*); |
| 182 | extern void clocksource_touch_watchdog(void); |
| 183 | extern void clocksource_change_rating(struct clocksource *cs, int rating); |
| 184 | extern void clocksource_suspend(void); |
| 185 | extern void clocksource_resume(void); |
| 186 | extern struct clocksource * __init clocksource_default_clock(void); |
| 187 | extern void clocksource_mark_unstable(struct clocksource *cs); |
| 188 | |
| 189 | extern u64 |
| 190 | clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles); |
| 191 | extern void |
| 192 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); |
| 193 | |
| 194 | /* |
| 195 | * Don't call __clocksource_register_scale directly, use |
| 196 | * clocksource_register_hz/khz |
| 197 | */ |
| 198 | extern int |
| 199 | __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); |
| 200 | extern void |
| 201 | __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq); |
| 202 | |
| 203 | /* |
| 204 | * Don't call this unless you are a default clocksource |
| 205 | * (AKA: jiffies) and absolutely have to. |
| 206 | */ |
| 207 | static inline int __clocksource_register(struct clocksource *cs) |
| 208 | { |
| 209 | return __clocksource_register_scale(cs, 1, 0); |
| 210 | } |
| 211 | |
| 212 | static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) |
| 213 | { |
| 214 | return __clocksource_register_scale(cs, 1, hz); |
| 215 | } |
| 216 | |
| 217 | static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) |
| 218 | { |
| 219 | return __clocksource_register_scale(cs, 1000, khz); |
| 220 | } |
| 221 | |
| 222 | static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz) |
| 223 | { |
| 224 | __clocksource_update_freq_scale(cs, 1, hz); |
| 225 | } |
| 226 | |
| 227 | static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz) |
| 228 | { |
| 229 | __clocksource_update_freq_scale(cs, 1000, khz); |
| 230 | } |
| 231 | |
| 232 | |
| 233 | extern int timekeeping_notify(struct clocksource *clock); |
| 234 | |
| 235 | extern cycle_t clocksource_mmio_readl_up(struct clocksource *); |
| 236 | extern cycle_t clocksource_mmio_readl_down(struct clocksource *); |
| 237 | extern cycle_t clocksource_mmio_readw_up(struct clocksource *); |
| 238 | extern cycle_t clocksource_mmio_readw_down(struct clocksource *); |
| 239 | |
| 240 | extern int clocksource_mmio_init(void __iomem *, const char *, |
| 241 | unsigned long, int, unsigned, cycle_t (*)(struct clocksource *)); |
| 242 | |
| 243 | extern int clocksource_i8253_init(void); |
| 244 | |
| 245 | #define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ |
| 246 | OF_DECLARE_1(clksrc, name, compat, fn) |
| 247 | |
| 248 | #ifdef CONFIG_CLKSRC_PROBE |
| 249 | extern void clocksource_probe(void); |
| 250 | #else |
| 251 | static inline void clocksource_probe(void) {} |
| 252 | #endif |
| 253 | |
| 254 | #define CLOCKSOURCE_ACPI_DECLARE(name, table_id, fn) \ |
| 255 | ACPI_DECLARE_PROBE_ENTRY(clksrc, name, table_id, 0, NULL, 0, fn) |
| 256 | |
| 257 | #endif /* _LINUX_CLOCKSOURCE_H */ |