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734efb46 | 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> | |
329c8d84 | 15 | #include <linux/cache.h> |
5d8b34fd | 16 | #include <linux/timer.h> |
f1b82746 | 17 | #include <linux/init.h> |
734efb46 | 18 | #include <asm/div64.h> |
19 | #include <asm/io.h> | |
20 | ||
21 | /* clocksource cycle base type */ | |
22 | typedef u64 cycle_t; | |
5d8b34fd | 23 | struct clocksource; |
734efb46 | 24 | |
ae7bd11b | 25 | #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
433bd805 | 26 | #include <asm/clocksource.h> |
ae7bd11b | 27 | #endif |
433bd805 | 28 | |
a038a353 PO |
29 | /** |
30 | * struct cyclecounter - hardware abstraction for a free running counter | |
31 | * Provides completely state-free accessors to the underlying hardware. | |
32 | * Depending on which hardware it reads, the cycle counter may wrap | |
33 | * around quickly. Locking rules (if necessary) have to be defined | |
34 | * by the implementor and user of specific instances of this API. | |
35 | * | |
36 | * @read: returns the current cycle value | |
37 | * @mask: bitmask for two's complement | |
38 | * subtraction of non 64 bit counters, | |
39 | * see CLOCKSOURCE_MASK() helper macro | |
40 | * @mult: cycle to nanosecond multiplier | |
41 | * @shift: cycle to nanosecond divisor (power of two) | |
42 | */ | |
43 | struct cyclecounter { | |
44 | cycle_t (*read)(const struct cyclecounter *cc); | |
45 | cycle_t mask; | |
46 | u32 mult; | |
47 | u32 shift; | |
48 | }; | |
49 | ||
50 | /** | |
51 | * struct timecounter - layer above a %struct cyclecounter which counts nanoseconds | |
52 | * Contains the state needed by timecounter_read() to detect | |
53 | * cycle counter wrap around. Initialize with | |
54 | * timecounter_init(). Also used to convert cycle counts into the | |
55 | * corresponding nanosecond counts with timecounter_cyc2time(). Users | |
56 | * of this code are responsible for initializing the underlying | |
57 | * cycle counter hardware, locking issues and reading the time | |
58 | * more often than the cycle counter wraps around. The nanosecond | |
59 | * counter will only wrap around after ~585 years. | |
60 | * | |
61 | * @cc: the cycle counter used by this instance | |
62 | * @cycle_last: most recent cycle counter value seen by | |
63 | * timecounter_read() | |
64 | * @nsec: continuously increasing count | |
65 | */ | |
66 | struct timecounter { | |
67 | const struct cyclecounter *cc; | |
68 | cycle_t cycle_last; | |
69 | u64 nsec; | |
70 | }; | |
71 | ||
72 | /** | |
73 | * cyclecounter_cyc2ns - converts cycle counter cycles to nanoseconds | |
b1b73d09 | 74 | * @cc: Pointer to cycle counter. |
a038a353 PO |
75 | * @cycles: Cycles |
76 | * | |
77 | * XXX - This could use some mult_lxl_ll() asm optimization. Same code | |
78 | * as in cyc2ns, but with unsigned result. | |
79 | */ | |
80 | static inline u64 cyclecounter_cyc2ns(const struct cyclecounter *cc, | |
81 | cycle_t cycles) | |
82 | { | |
83 | u64 ret = (u64)cycles; | |
84 | ret = (ret * cc->mult) >> cc->shift; | |
85 | return ret; | |
86 | } | |
87 | ||
88 | /** | |
89 | * timecounter_init - initialize a time counter | |
90 | * @tc: Pointer to time counter which is to be initialized/reset | |
91 | * @cc: A cycle counter, ready to be used. | |
92 | * @start_tstamp: Arbitrary initial time stamp. | |
93 | * | |
94 | * After this call the current cycle register (roughly) corresponds to | |
95 | * the initial time stamp. Every call to timecounter_read() increments | |
96 | * the time stamp counter by the number of elapsed nanoseconds. | |
97 | */ | |
98 | extern void timecounter_init(struct timecounter *tc, | |
99 | const struct cyclecounter *cc, | |
100 | u64 start_tstamp); | |
101 | ||
102 | /** | |
103 | * timecounter_read - return nanoseconds elapsed since timecounter_init() | |
104 | * plus the initial time stamp | |
105 | * @tc: Pointer to time counter. | |
106 | * | |
107 | * In other words, keeps track of time since the same epoch as | |
108 | * the function which generated the initial time stamp. | |
109 | */ | |
110 | extern u64 timecounter_read(struct timecounter *tc); | |
111 | ||
112 | /** | |
113 | * timecounter_cyc2time - convert a cycle counter to same | |
114 | * time base as values returned by | |
115 | * timecounter_read() | |
116 | * @tc: Pointer to time counter. | |
b1b73d09 | 117 | * @cycle_tstamp: a value returned by tc->cc->read() |
a038a353 PO |
118 | * |
119 | * Cycle counts that are converted correctly as long as they | |
120 | * fall into the interval [-1/2 max cycle count, +1/2 max cycle count], | |
121 | * with "max cycle count" == cs->mask+1. | |
122 | * | |
123 | * This allows conversion of cycle counter values which were generated | |
124 | * in the past. | |
125 | */ | |
126 | extern u64 timecounter_cyc2time(struct timecounter *tc, | |
127 | cycle_t cycle_tstamp); | |
128 | ||
734efb46 | 129 | /** |
130 | * struct clocksource - hardware abstraction for a free running counter | |
131 | * Provides mostly state-free accessors to the underlying hardware. | |
a038a353 | 132 | * This is the structure used for system time. |
734efb46 | 133 | * |
134 | * @name: ptr to clocksource name | |
135 | * @list: list head for registration | |
136 | * @rating: rating value for selection (higher is better) | |
137 | * To avoid rating inflation the following | |
138 | * list should give you a guide as to how | |
139 | * to assign your clocksource a rating | |
140 | * 1-99: Unfit for real use | |
141 | * Only available for bootup and testing purposes. | |
142 | * 100-199: Base level usability. | |
143 | * Functional for real use, but not desired. | |
144 | * 200-299: Good. | |
145 | * A correct and usable clocksource. | |
146 | * 300-399: Desired. | |
147 | * A reasonably fast and accurate clocksource. | |
148 | * 400-499: Perfect | |
149 | * The ideal clocksource. A must-use where | |
150 | * available. | |
8e19608e | 151 | * @read: returns a cycle value, passes clocksource as argument |
4614e6ad MD |
152 | * @enable: optional function to enable the clocksource |
153 | * @disable: optional function to disable the clocksource | |
734efb46 | 154 | * @mask: bitmask for two's complement |
155 | * subtraction of non 64 bit counters | |
0a544198 | 156 | * @mult: cycle to nanosecond multiplier |
734efb46 | 157 | * @shift: cycle to nanosecond divisor (power of two) |
98962465 | 158 | * @max_idle_ns: max idle time permitted by the clocksource (nsecs) |
b1b73d09 | 159 | * @maxadj: maximum adjustment value to mult (~11%) |
73b08d2a | 160 | * @flags: flags describing special properties |
433bd805 | 161 | * @archdata: arch-specific data |
c54a42b1 | 162 | * @suspend: suspend function for the clocksource, if necessary |
b52f52a0 | 163 | * @resume: resume function for the clocksource, if necessary |
b1b73d09 | 164 | * @cycle_last: most recent cycle counter value seen by ::read() |
734efb46 | 165 | */ |
166 | struct clocksource { | |
329c8d84 | 167 | /* |
369db4c9 TG |
168 | * Hotpath data, fits in a single cache line when the |
169 | * clocksource itself is cacheline aligned. | |
329c8d84 | 170 | */ |
8e19608e | 171 | cycle_t (*read)(struct clocksource *cs); |
369db4c9 | 172 | cycle_t cycle_last; |
734efb46 | 173 | cycle_t mask; |
174 | u32 mult; | |
175 | u32 shift; | |
98962465 | 176 | u64 max_idle_ns; |
d65670a7 | 177 | u32 maxadj; |
ae7bd11b | 178 | #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
433bd805 | 179 | struct arch_clocksource_data archdata; |
0aa366f3 | 180 | #endif |
433bd805 | 181 | |
369db4c9 TG |
182 | const char *name; |
183 | struct list_head list; | |
184 | int rating; | |
369db4c9 TG |
185 | int (*enable)(struct clocksource *cs); |
186 | void (*disable)(struct clocksource *cs); | |
187 | unsigned long flags; | |
188 | void (*suspend)(struct clocksource *cs); | |
189 | void (*resume)(struct clocksource *cs); | |
5d8b34fd | 190 | |
b1b73d09 | 191 | /* private: */ |
5d8b34fd TG |
192 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
193 | /* Watchdog related data, used by the framework */ | |
194 | struct list_head wd_list; | |
b5199515 | 195 | cycle_t cs_last; |
5d8b34fd TG |
196 | cycle_t wd_last; |
197 | #endif | |
369db4c9 | 198 | } ____cacheline_aligned; |
734efb46 | 199 | |
73b08d2a TG |
200 | /* |
201 | * Clock source flags bits:: | |
202 | */ | |
5d8b34fd TG |
203 | #define CLOCK_SOURCE_IS_CONTINUOUS 0x01 |
204 | #define CLOCK_SOURCE_MUST_VERIFY 0x02 | |
205 | ||
206 | #define CLOCK_SOURCE_WATCHDOG 0x10 | |
207 | #define CLOCK_SOURCE_VALID_FOR_HRES 0x20 | |
c55c87c8 | 208 | #define CLOCK_SOURCE_UNSTABLE 0x40 |
73b08d2a | 209 | |
7f9f303a | 210 | /* simplify initialization of mask field */ |
1d76c262 | 211 | #define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1) |
734efb46 | 212 | |
213 | /** | |
214 | * clocksource_khz2mult - calculates mult from khz and shift | |
215 | * @khz: Clocksource frequency in KHz | |
216 | * @shift_constant: Clocksource shift factor | |
217 | * | |
218 | * Helper functions that converts a khz counter frequency to a timsource | |
219 | * multiplier, given the clocksource shift value | |
220 | */ | |
221 | static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) | |
222 | { | |
223 | /* khz = cyc/(Million ns) | |
224 | * mult/2^shift = ns/cyc | |
225 | * mult = ns/cyc * 2^shift | |
226 | * mult = 1Million/khz * 2^shift | |
227 | * mult = 1000000 * 2^shift / khz | |
228 | * mult = (1000000<<shift) / khz | |
229 | */ | |
230 | u64 tmp = ((u64)1000000) << shift_constant; | |
231 | ||
232 | tmp += khz/2; /* round for do_div */ | |
233 | do_div(tmp, khz); | |
234 | ||
235 | return (u32)tmp; | |
236 | } | |
237 | ||
238 | /** | |
239 | * clocksource_hz2mult - calculates mult from hz and shift | |
240 | * @hz: Clocksource frequency in Hz | |
241 | * @shift_constant: Clocksource shift factor | |
242 | * | |
243 | * Helper functions that converts a hz counter | |
244 | * frequency to a timsource multiplier, given the | |
245 | * clocksource shift value | |
246 | */ | |
247 | static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) | |
248 | { | |
249 | /* hz = cyc/(Billion ns) | |
250 | * mult/2^shift = ns/cyc | |
251 | * mult = ns/cyc * 2^shift | |
252 | * mult = 1Billion/hz * 2^shift | |
253 | * mult = 1000000000 * 2^shift / hz | |
254 | * mult = (1000000000<<shift) / hz | |
255 | */ | |
256 | u64 tmp = ((u64)1000000000) << shift_constant; | |
257 | ||
258 | tmp += hz/2; /* round for do_div */ | |
259 | do_div(tmp, hz); | |
260 | ||
261 | return (u32)tmp; | |
262 | } | |
263 | ||
734efb46 | 264 | /** |
155ec602 | 265 | * clocksource_cyc2ns - converts clocksource cycles to nanoseconds |
b1b73d09 KK |
266 | * @cycles: cycles |
267 | * @mult: cycle to nanosecond multiplier | |
268 | * @shift: cycle to nanosecond divisor (power of two) | |
734efb46 | 269 | * |
155ec602 | 270 | * Converts cycles to nanoseconds, using the given mult and shift. |
734efb46 | 271 | * |
272 | * XXX - This could use some mult_lxl_ll() asm optimization | |
273 | */ | |
155ec602 | 274 | static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift) |
734efb46 | 275 | { |
155ec602 | 276 | return ((u64) cycles * mult) >> shift; |
5eb6d205 | 277 | } |
278 | ||
279 | ||
92c7e002 | 280 | extern int clocksource_register(struct clocksource*); |
4713e22c | 281 | extern void clocksource_unregister(struct clocksource*); |
7c3078b6 | 282 | extern void clocksource_touch_watchdog(void); |
92c7e002 TG |
283 | extern struct clocksource* clocksource_get_next(void); |
284 | extern void clocksource_change_rating(struct clocksource *cs, int rating); | |
c54a42b1 | 285 | extern void clocksource_suspend(void); |
b52f52a0 | 286 | extern void clocksource_resume(void); |
f1b82746 | 287 | extern struct clocksource * __init __weak clocksource_default_clock(void); |
7285dd7f | 288 | extern void clocksource_mark_unstable(struct clocksource *cs); |
734efb46 | 289 | |
7d2f944a TG |
290 | extern void |
291 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); | |
292 | ||
d7e81c26 JS |
293 | /* |
294 | * Don't call __clocksource_register_scale directly, use | |
295 | * clocksource_register_hz/khz | |
296 | */ | |
297 | extern int | |
298 | __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); | |
852db46d JS |
299 | extern void |
300 | __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq); | |
d7e81c26 JS |
301 | |
302 | static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) | |
303 | { | |
304 | return __clocksource_register_scale(cs, 1, hz); | |
305 | } | |
306 | ||
307 | static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) | |
308 | { | |
309 | return __clocksource_register_scale(cs, 1000, khz); | |
310 | } | |
311 | ||
852db46d JS |
312 | static inline void __clocksource_updatefreq_hz(struct clocksource *cs, u32 hz) |
313 | { | |
314 | __clocksource_updatefreq_scale(cs, 1, hz); | |
315 | } | |
316 | ||
317 | static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz) | |
318 | { | |
319 | __clocksource_updatefreq_scale(cs, 1000, khz); | |
320 | } | |
d7e81c26 | 321 | |
acc9a9dc | 322 | #ifdef CONFIG_GENERIC_TIME_VSYSCALL |
0696b711 | 323 | extern void |
7615856e JS |
324 | update_vsyscall(struct timespec *ts, struct timespec *wtm, |
325 | struct clocksource *c, u32 mult); | |
2c622148 | 326 | extern void update_vsyscall_tz(void); |
acc9a9dc | 327 | #else |
0696b711 | 328 | static inline void |
7615856e JS |
329 | update_vsyscall(struct timespec *ts, struct timespec *wtm, |
330 | struct clocksource *c, u32 mult) | |
acc9a9dc | 331 | { |
332 | } | |
2c622148 TB |
333 | |
334 | static inline void update_vsyscall_tz(void) | |
335 | { | |
336 | } | |
acc9a9dc | 337 | #endif |
338 | ||
75c5158f MS |
339 | extern void timekeeping_notify(struct clocksource *clock); |
340 | ||
442c8176 RK |
341 | extern cycle_t clocksource_mmio_readl_up(struct clocksource *); |
342 | extern cycle_t clocksource_mmio_readl_down(struct clocksource *); | |
343 | extern cycle_t clocksource_mmio_readw_up(struct clocksource *); | |
344 | extern cycle_t clocksource_mmio_readw_down(struct clocksource *); | |
345 | ||
346 | extern int clocksource_mmio_init(void __iomem *, const char *, | |
347 | unsigned long, int, unsigned, cycle_t (*)(struct clocksource *)); | |
348 | ||
8c414ff3 RK |
349 | extern int clocksource_i8253_init(void); |
350 | ||
734efb46 | 351 | #endif /* _LINUX_CLOCKSOURCE_H */ |