Commit | Line | Data |
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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; |
09ac369c | 24 | struct module; |
734efb46 | 25 | |
ae7bd11b | 26 | #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
433bd805 | 27 | #include <asm/clocksource.h> |
ae7bd11b | 28 | #endif |
433bd805 | 29 | |
a038a353 PO |
30 | /** |
31 | * struct cyclecounter - hardware abstraction for a free running counter | |
32 | * Provides completely state-free accessors to the underlying hardware. | |
33 | * Depending on which hardware it reads, the cycle counter may wrap | |
34 | * around quickly. Locking rules (if necessary) have to be defined | |
35 | * by the implementor and user of specific instances of this API. | |
36 | * | |
37 | * @read: returns the current cycle value | |
38 | * @mask: bitmask for two's complement | |
39 | * subtraction of non 64 bit counters, | |
40 | * see CLOCKSOURCE_MASK() helper macro | |
41 | * @mult: cycle to nanosecond multiplier | |
42 | * @shift: cycle to nanosecond divisor (power of two) | |
43 | */ | |
44 | struct cyclecounter { | |
45 | cycle_t (*read)(const struct cyclecounter *cc); | |
46 | cycle_t mask; | |
47 | u32 mult; | |
48 | u32 shift; | |
49 | }; | |
50 | ||
51 | /** | |
52 | * struct timecounter - layer above a %struct cyclecounter which counts nanoseconds | |
53 | * Contains the state needed by timecounter_read() to detect | |
54 | * cycle counter wrap around. Initialize with | |
55 | * timecounter_init(). Also used to convert cycle counts into the | |
56 | * corresponding nanosecond counts with timecounter_cyc2time(). Users | |
57 | * of this code are responsible for initializing the underlying | |
58 | * cycle counter hardware, locking issues and reading the time | |
59 | * more often than the cycle counter wraps around. The nanosecond | |
60 | * counter will only wrap around after ~585 years. | |
61 | * | |
62 | * @cc: the cycle counter used by this instance | |
63 | * @cycle_last: most recent cycle counter value seen by | |
64 | * timecounter_read() | |
65 | * @nsec: continuously increasing count | |
66 | */ | |
67 | struct timecounter { | |
68 | const struct cyclecounter *cc; | |
69 | cycle_t cycle_last; | |
70 | u64 nsec; | |
71 | }; | |
72 | ||
73 | /** | |
74 | * cyclecounter_cyc2ns - converts cycle counter cycles to nanoseconds | |
b1b73d09 | 75 | * @cc: Pointer to cycle counter. |
a038a353 PO |
76 | * @cycles: Cycles |
77 | * | |
78 | * XXX - This could use some mult_lxl_ll() asm optimization. Same code | |
79 | * as in cyc2ns, but with unsigned result. | |
80 | */ | |
81 | static inline u64 cyclecounter_cyc2ns(const struct cyclecounter *cc, | |
82 | cycle_t cycles) | |
83 | { | |
84 | u64 ret = (u64)cycles; | |
85 | ret = (ret * cc->mult) >> cc->shift; | |
86 | return ret; | |
87 | } | |
88 | ||
89 | /** | |
90 | * timecounter_init - initialize a time counter | |
91 | * @tc: Pointer to time counter which is to be initialized/reset | |
92 | * @cc: A cycle counter, ready to be used. | |
93 | * @start_tstamp: Arbitrary initial time stamp. | |
94 | * | |
95 | * After this call the current cycle register (roughly) corresponds to | |
96 | * the initial time stamp. Every call to timecounter_read() increments | |
97 | * the time stamp counter by the number of elapsed nanoseconds. | |
98 | */ | |
99 | extern void timecounter_init(struct timecounter *tc, | |
100 | const struct cyclecounter *cc, | |
101 | u64 start_tstamp); | |
102 | ||
103 | /** | |
104 | * timecounter_read - return nanoseconds elapsed since timecounter_init() | |
105 | * plus the initial time stamp | |
106 | * @tc: Pointer to time counter. | |
107 | * | |
108 | * In other words, keeps track of time since the same epoch as | |
109 | * the function which generated the initial time stamp. | |
110 | */ | |
111 | extern u64 timecounter_read(struct timecounter *tc); | |
112 | ||
113 | /** | |
114 | * timecounter_cyc2time - convert a cycle counter to same | |
115 | * time base as values returned by | |
116 | * timecounter_read() | |
117 | * @tc: Pointer to time counter. | |
b1b73d09 | 118 | * @cycle_tstamp: a value returned by tc->cc->read() |
a038a353 PO |
119 | * |
120 | * Cycle counts that are converted correctly as long as they | |
121 | * fall into the interval [-1/2 max cycle count, +1/2 max cycle count], | |
122 | * with "max cycle count" == cs->mask+1. | |
123 | * | |
124 | * This allows conversion of cycle counter values which were generated | |
125 | * in the past. | |
126 | */ | |
127 | extern u64 timecounter_cyc2time(struct timecounter *tc, | |
128 | cycle_t cycle_tstamp); | |
129 | ||
734efb46 | 130 | /** |
131 | * struct clocksource - hardware abstraction for a free running counter | |
132 | * Provides mostly state-free accessors to the underlying hardware. | |
a038a353 | 133 | * This is the structure used for system time. |
734efb46 | 134 | * |
135 | * @name: ptr to clocksource name | |
136 | * @list: list head for registration | |
137 | * @rating: rating value for selection (higher is better) | |
138 | * To avoid rating inflation the following | |
139 | * list should give you a guide as to how | |
140 | * to assign your clocksource a rating | |
141 | * 1-99: Unfit for real use | |
142 | * Only available for bootup and testing purposes. | |
143 | * 100-199: Base level usability. | |
144 | * Functional for real use, but not desired. | |
145 | * 200-299: Good. | |
146 | * A correct and usable clocksource. | |
147 | * 300-399: Desired. | |
148 | * A reasonably fast and accurate clocksource. | |
149 | * 400-499: Perfect | |
150 | * The ideal clocksource. A must-use where | |
151 | * available. | |
8e19608e | 152 | * @read: returns a cycle value, passes clocksource as argument |
4614e6ad MD |
153 | * @enable: optional function to enable the clocksource |
154 | * @disable: optional function to disable the clocksource | |
734efb46 | 155 | * @mask: bitmask for two's complement |
156 | * subtraction of non 64 bit counters | |
0a544198 | 157 | * @mult: cycle to nanosecond multiplier |
734efb46 | 158 | * @shift: cycle to nanosecond divisor (power of two) |
98962465 | 159 | * @max_idle_ns: max idle time permitted by the clocksource (nsecs) |
b1b73d09 | 160 | * @maxadj: maximum adjustment value to mult (~11%) |
73b08d2a | 161 | * @flags: flags describing special properties |
433bd805 | 162 | * @archdata: arch-specific data |
c54a42b1 | 163 | * @suspend: suspend function for the clocksource, if necessary |
b52f52a0 | 164 | * @resume: resume function for the clocksource, if necessary |
b1b73d09 | 165 | * @cycle_last: most recent cycle counter value seen by ::read() |
09ac369c | 166 | * @owner: module reference, must be set by clocksource in modules |
734efb46 | 167 | */ |
168 | struct clocksource { | |
329c8d84 | 169 | /* |
369db4c9 TG |
170 | * Hotpath data, fits in a single cache line when the |
171 | * clocksource itself is cacheline aligned. | |
329c8d84 | 172 | */ |
8e19608e | 173 | cycle_t (*read)(struct clocksource *cs); |
369db4c9 | 174 | cycle_t cycle_last; |
734efb46 | 175 | cycle_t mask; |
176 | u32 mult; | |
177 | u32 shift; | |
98962465 | 178 | u64 max_idle_ns; |
d65670a7 | 179 | u32 maxadj; |
ae7bd11b | 180 | #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
433bd805 | 181 | struct arch_clocksource_data archdata; |
0aa366f3 | 182 | #endif |
433bd805 | 183 | |
369db4c9 TG |
184 | const char *name; |
185 | struct list_head list; | |
186 | int rating; | |
369db4c9 TG |
187 | int (*enable)(struct clocksource *cs); |
188 | void (*disable)(struct clocksource *cs); | |
189 | unsigned long flags; | |
190 | void (*suspend)(struct clocksource *cs); | |
191 | void (*resume)(struct clocksource *cs); | |
5d8b34fd | 192 | |
b1b73d09 | 193 | /* private: */ |
5d8b34fd TG |
194 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
195 | /* Watchdog related data, used by the framework */ | |
196 | struct list_head wd_list; | |
b5199515 | 197 | cycle_t cs_last; |
5d8b34fd TG |
198 | cycle_t wd_last; |
199 | #endif | |
09ac369c | 200 | struct module *owner; |
369db4c9 | 201 | } ____cacheline_aligned; |
734efb46 | 202 | |
73b08d2a TG |
203 | /* |
204 | * Clock source flags bits:: | |
205 | */ | |
5d8b34fd TG |
206 | #define CLOCK_SOURCE_IS_CONTINUOUS 0x01 |
207 | #define CLOCK_SOURCE_MUST_VERIFY 0x02 | |
208 | ||
209 | #define CLOCK_SOURCE_WATCHDOG 0x10 | |
210 | #define CLOCK_SOURCE_VALID_FOR_HRES 0x20 | |
c55c87c8 | 211 | #define CLOCK_SOURCE_UNSTABLE 0x40 |
5caf4636 | 212 | #define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80 |
332962f2 | 213 | #define CLOCK_SOURCE_RESELECT 0x100 |
73b08d2a | 214 | |
7f9f303a | 215 | /* simplify initialization of mask field */ |
1d76c262 | 216 | #define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1) |
734efb46 | 217 | |
218 | /** | |
219 | * clocksource_khz2mult - calculates mult from khz and shift | |
220 | * @khz: Clocksource frequency in KHz | |
221 | * @shift_constant: Clocksource shift factor | |
222 | * | |
223 | * Helper functions that converts a khz counter frequency to a timsource | |
224 | * multiplier, given the clocksource shift value | |
225 | */ | |
226 | static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) | |
227 | { | |
228 | /* khz = cyc/(Million ns) | |
229 | * mult/2^shift = ns/cyc | |
230 | * mult = ns/cyc * 2^shift | |
231 | * mult = 1Million/khz * 2^shift | |
232 | * mult = 1000000 * 2^shift / khz | |
233 | * mult = (1000000<<shift) / khz | |
234 | */ | |
235 | u64 tmp = ((u64)1000000) << shift_constant; | |
236 | ||
237 | tmp += khz/2; /* round for do_div */ | |
238 | do_div(tmp, khz); | |
239 | ||
240 | return (u32)tmp; | |
241 | } | |
242 | ||
243 | /** | |
244 | * clocksource_hz2mult - calculates mult from hz and shift | |
245 | * @hz: Clocksource frequency in Hz | |
246 | * @shift_constant: Clocksource shift factor | |
247 | * | |
248 | * Helper functions that converts a hz counter | |
249 | * frequency to a timsource multiplier, given the | |
250 | * clocksource shift value | |
251 | */ | |
252 | static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) | |
253 | { | |
254 | /* hz = cyc/(Billion ns) | |
255 | * mult/2^shift = ns/cyc | |
256 | * mult = ns/cyc * 2^shift | |
257 | * mult = 1Billion/hz * 2^shift | |
258 | * mult = 1000000000 * 2^shift / hz | |
259 | * mult = (1000000000<<shift) / hz | |
260 | */ | |
261 | u64 tmp = ((u64)1000000000) << shift_constant; | |
262 | ||
263 | tmp += hz/2; /* round for do_div */ | |
264 | do_div(tmp, hz); | |
265 | ||
266 | return (u32)tmp; | |
267 | } | |
268 | ||
734efb46 | 269 | /** |
155ec602 | 270 | * clocksource_cyc2ns - converts clocksource cycles to nanoseconds |
b1b73d09 KK |
271 | * @cycles: cycles |
272 | * @mult: cycle to nanosecond multiplier | |
273 | * @shift: cycle to nanosecond divisor (power of two) | |
734efb46 | 274 | * |
155ec602 | 275 | * Converts cycles to nanoseconds, using the given mult and shift. |
734efb46 | 276 | * |
277 | * XXX - This could use some mult_lxl_ll() asm optimization | |
278 | */ | |
155ec602 | 279 | static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift) |
734efb46 | 280 | { |
155ec602 | 281 | return ((u64) cycles * mult) >> shift; |
5eb6d205 | 282 | } |
283 | ||
284 | ||
92c7e002 | 285 | extern int clocksource_register(struct clocksource*); |
a89c7edb | 286 | extern int clocksource_unregister(struct clocksource*); |
7c3078b6 | 287 | extern void clocksource_touch_watchdog(void); |
92c7e002 TG |
288 | extern struct clocksource* clocksource_get_next(void); |
289 | extern void clocksource_change_rating(struct clocksource *cs, int rating); | |
c54a42b1 | 290 | extern void clocksource_suspend(void); |
b52f52a0 | 291 | extern void clocksource_resume(void); |
f1b82746 | 292 | extern struct clocksource * __init __weak clocksource_default_clock(void); |
7285dd7f | 293 | extern void clocksource_mark_unstable(struct clocksource *cs); |
734efb46 | 294 | |
87d8b9eb SB |
295 | extern u64 |
296 | clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask); | |
7d2f944a TG |
297 | extern void |
298 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); | |
299 | ||
d7e81c26 JS |
300 | /* |
301 | * Don't call __clocksource_register_scale directly, use | |
302 | * clocksource_register_hz/khz | |
303 | */ | |
304 | extern int | |
305 | __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); | |
852db46d JS |
306 | extern void |
307 | __clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq); | |
d7e81c26 JS |
308 | |
309 | static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) | |
310 | { | |
311 | return __clocksource_register_scale(cs, 1, hz); | |
312 | } | |
313 | ||
314 | static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) | |
315 | { | |
316 | return __clocksource_register_scale(cs, 1000, khz); | |
317 | } | |
318 | ||
852db46d JS |
319 | static inline void __clocksource_updatefreq_hz(struct clocksource *cs, u32 hz) |
320 | { | |
321 | __clocksource_updatefreq_scale(cs, 1, hz); | |
322 | } | |
323 | ||
324 | static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz) | |
325 | { | |
326 | __clocksource_updatefreq_scale(cs, 1000, khz); | |
327 | } | |
d7e81c26 | 328 | |
acc9a9dc | 329 | |
ba919d1c | 330 | extern int timekeeping_notify(struct clocksource *clock); |
75c5158f | 331 | |
442c8176 RK |
332 | extern cycle_t clocksource_mmio_readl_up(struct clocksource *); |
333 | extern cycle_t clocksource_mmio_readl_down(struct clocksource *); | |
334 | extern cycle_t clocksource_mmio_readw_up(struct clocksource *); | |
335 | extern cycle_t clocksource_mmio_readw_down(struct clocksource *); | |
336 | ||
337 | extern int clocksource_mmio_init(void __iomem *, const char *, | |
338 | unsigned long, int, unsigned, cycle_t (*)(struct clocksource *)); | |
339 | ||
8c414ff3 RK |
340 | extern int clocksource_i8253_init(void); |
341 | ||
3d5a9658 AB |
342 | struct device_node; |
343 | typedef void(*clocksource_of_init_fn)(struct device_node *); | |
ae278a93 SW |
344 | #ifdef CONFIG_CLKSRC_OF |
345 | extern void clocksource_of_init(void); | |
346 | ||
347 | #define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ | |
348 | static const struct of_device_id __clksrc_of_table_##name \ | |
349 | __used __section(__clksrc_of_table) \ | |
3d5a9658 AB |
350 | = { .compatible = compat, \ |
351 | .data = (fn == (clocksource_of_init_fn)NULL) ? fn : fn } | |
e1d7ef1c | 352 | #else |
e0c25362 | 353 | static inline void clocksource_of_init(void) {} |
3d5a9658 AB |
354 | #define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ |
355 | static const struct of_device_id __clksrc_of_table_##name \ | |
356 | __attribute__((unused)) \ | |
357 | = { .compatible = compat, \ | |
358 | .data = (fn == (clocksource_of_init_fn)NULL) ? fn : fn } | |
ae278a93 SW |
359 | #endif |
360 | ||
734efb46 | 361 | #endif /* _LINUX_CLOCKSOURCE_H */ |