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john stultz734efb42006-06-26 00:25:05 -07001/* 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>
Eric Dumazet329c8d82007-05-08 00:27:57 -070015#include <linux/cache.h>
Thomas Gleixner5d8b34f2007-02-16 01:27:43 -080016#include <linux/timer.h>
Martin Schwidefskyf1b82742009-08-14 15:47:21 +020017#include <linux/init.h>
john stultz734efb42006-06-26 00:25:05 -070018#include <asm/div64.h>
19#include <asm/io.h>
20
21/* clocksource cycle base type */
22typedef u64 cycle_t;
Thomas Gleixner5d8b34f2007-02-16 01:27:43 -080023struct clocksource;
john stultz734efb42006-06-26 00:25:05 -070024
H. Peter Anvinae7bd112011-07-21 13:34:05 -070025#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
Andy Lutomirski433bd802011-07-13 09:24:13 -040026#include <asm/clocksource.h>
H. Peter Anvinae7bd112011-07-21 13:34:05 -070027#endif
Andy Lutomirski433bd802011-07-13 09:24:13 -040028
john stultz734efb42006-06-26 00:25:05 -070029/**
Patrick Ohlya038a352009-02-12 05:03:34 +000030 * 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 */
43struct 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 */
66struct 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
Kusanagi Kouichib1b73d02011-12-19 18:13:19 +090074 * @cc: Pointer to cycle counter.
Patrick Ohlya038a352009-02-12 05:03:34 +000075 * @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 */
80static 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 */
98extern 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 */
110extern 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.
Kusanagi Kouichib1b73d02011-12-19 18:13:19 +0900117 * @cycle_tstamp: a value returned by tc->cc->read()
Patrick Ohlya038a352009-02-12 05:03:34 +0000118 *
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 */
126extern u64 timecounter_cyc2time(struct timecounter *tc,
127 cycle_t cycle_tstamp);
128
129/**
john stultz734efb42006-06-26 00:25:05 -0700130 * struct clocksource - hardware abstraction for a free running counter
131 * Provides mostly state-free accessors to the underlying hardware.
Patrick Ohlya038a352009-02-12 05:03:34 +0000132 * This is the structure used for system time.
john stultz734efb42006-06-26 00:25:05 -0700133 *
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.
Magnus Damm8e196082009-04-21 12:24:00 -0700151 * @read: returns a cycle value, passes clocksource as argument
Magnus Damm4614e6a2009-04-21 12:24:02 -0700152 * @enable: optional function to enable the clocksource
153 * @disable: optional function to disable the clocksource
john stultz734efb42006-06-26 00:25:05 -0700154 * @mask: bitmask for two's complement
155 * subtraction of non 64 bit counters
Martin Schwidefsky0a544192009-08-14 15:47:28 +0200156 * @mult: cycle to nanosecond multiplier
john stultz734efb42006-06-26 00:25:05 -0700157 * @shift: cycle to nanosecond divisor (power of two)
Jon Hunter98962462009-08-18 12:45:10 -0500158 * @max_idle_ns: max idle time permitted by the clocksource (nsecs)
Kusanagi Kouichib1b73d02011-12-19 18:13:19 +0900159 * @maxadj: maximum adjustment value to mult (~11%)
Thomas Gleixner73b08d22007-02-16 01:27:36 -0800160 * @flags: flags describing special properties
Andy Lutomirski433bd802011-07-13 09:24:13 -0400161 * @archdata: arch-specific data
Magnus Dammc54a42b2010-02-02 14:41:41 -0800162 * @suspend: suspend function for the clocksource, if necessary
Thomas Gleixnerb52f52a2007-05-09 02:35:15 -0700163 * @resume: resume function for the clocksource, if necessary
Kusanagi Kouichib1b73d02011-12-19 18:13:19 +0900164 * @cycle_last: most recent cycle counter value seen by ::read()
john stultz734efb42006-06-26 00:25:05 -0700165 */
166struct clocksource {
Eric Dumazet329c8d82007-05-08 00:27:57 -0700167 /*
Thomas Gleixner369db4c2011-05-18 21:33:40 +0000168 * Hotpath data, fits in a single cache line when the
169 * clocksource itself is cacheline aligned.
Eric Dumazet329c8d82007-05-08 00:27:57 -0700170 */
Magnus Damm8e196082009-04-21 12:24:00 -0700171 cycle_t (*read)(struct clocksource *cs);
Thomas Gleixner369db4c2011-05-18 21:33:40 +0000172 cycle_t cycle_last;
john stultz734efb42006-06-26 00:25:05 -0700173 cycle_t mask;
174 u32 mult;
175 u32 shift;
Jon Hunter98962462009-08-18 12:45:10 -0500176 u64 max_idle_ns;
John Stultzd65670a2011-10-31 17:06:35 -0400177 u32 maxadj;
H. Peter Anvinae7bd112011-07-21 13:34:05 -0700178#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
Andy Lutomirski433bd802011-07-13 09:24:13 -0400179 struct arch_clocksource_data archdata;
Tony Luck0aa366f2007-07-20 11:22:30 -0700180#endif
Andy Lutomirski433bd802011-07-13 09:24:13 -0400181
Thomas Gleixner369db4c2011-05-18 21:33:40 +0000182 const char *name;
183 struct list_head list;
184 int rating;
Thomas Gleixner369db4c2011-05-18 21:33:40 +0000185 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);
Thomas Gleixner5d8b34f2007-02-16 01:27:43 -0800190
Kusanagi Kouichib1b73d02011-12-19 18:13:19 +0900191 /* private: */
Thomas Gleixner5d8b34f2007-02-16 01:27:43 -0800192#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
193 /* Watchdog related data, used by the framework */
194 struct list_head wd_list;
Thomas Gleixnerb5199512011-06-16 16:22:08 +0200195 cycle_t cs_last;
Thomas Gleixner5d8b34f2007-02-16 01:27:43 -0800196 cycle_t wd_last;
197#endif
Thomas Gleixner369db4c2011-05-18 21:33:40 +0000198} ____cacheline_aligned;
john stultz734efb42006-06-26 00:25:05 -0700199
Thomas Gleixner73b08d22007-02-16 01:27:36 -0800200/*
201 * Clock source flags bits::
202 */
Thomas Gleixner5d8b34f2007-02-16 01:27:43 -0800203#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
Martin Schwidefskyc55c87c2009-08-14 15:47:25 +0200208#define CLOCK_SOURCE_UNSTABLE 0x40
Thomas Gleixner73b08d22007-02-16 01:27:36 -0800209
Jim Cromie7f9f3032006-06-26 00:25:15 -0700210/* simplify initialization of mask field */
Atsushi Nemoto1d76c262008-01-30 13:30:01 +0100211#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
john stultz734efb42006-06-26 00:25:05 -0700212
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 */
221static 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 */
247static 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
264/**
Martin Schwidefsky155ec602009-08-14 15:47:26 +0200265 * clocksource_cyc2ns - converts clocksource cycles to nanoseconds
Kusanagi Kouichib1b73d02011-12-19 18:13:19 +0900266 * @cycles: cycles
267 * @mult: cycle to nanosecond multiplier
268 * @shift: cycle to nanosecond divisor (power of two)
john stultz734efb42006-06-26 00:25:05 -0700269 *
Martin Schwidefsky155ec602009-08-14 15:47:26 +0200270 * Converts cycles to nanoseconds, using the given mult and shift.
john stultz734efb42006-06-26 00:25:05 -0700271 *
272 * XXX - This could use some mult_lxl_ll() asm optimization
273 */
Martin Schwidefsky155ec602009-08-14 15:47:26 +0200274static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)
john stultz734efb42006-06-26 00:25:05 -0700275{
Martin Schwidefsky155ec602009-08-14 15:47:26 +0200276 return ((u64) cycles * mult) >> shift;
john stultz5eb6d202006-06-26 00:25:07 -0700277}
278
279
Thomas Gleixner92c7e002007-02-16 01:27:33 -0800280extern int clocksource_register(struct clocksource*);
Thomas Gleixner4713e22c2008-01-30 13:30:02 +0100281extern void clocksource_unregister(struct clocksource*);
Jason Wessel7c3078b2008-02-15 14:55:54 -0600282extern void clocksource_touch_watchdog(void);
Thomas Gleixner92c7e002007-02-16 01:27:33 -0800283extern struct clocksource* clocksource_get_next(void);
284extern void clocksource_change_rating(struct clocksource *cs, int rating);
Magnus Dammc54a42b2010-02-02 14:41:41 -0800285extern void clocksource_suspend(void);
Thomas Gleixnerb52f52a2007-05-09 02:35:15 -0700286extern void clocksource_resume(void);
Martin Schwidefskyf1b82742009-08-14 15:47:21 +0200287extern struct clocksource * __init __weak clocksource_default_clock(void);
Thomas Gleixner7285dd72009-08-28 20:25:24 +0200288extern void clocksource_mark_unstable(struct clocksource *cs);
john stultz734efb42006-06-26 00:25:05 -0700289
Thomas Gleixner7d2f9442009-11-11 14:05:29 +0000290extern void
291clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
292
John Stultzd7e81c22010-05-07 18:07:38 -0700293/*
294 * Don't call __clocksource_register_scale directly, use
295 * clocksource_register_hz/khz
296 */
297extern int
298__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
John Stultz852db462010-07-13 17:56:28 -0700299extern void
300__clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq);
John Stultzd7e81c22010-05-07 18:07:38 -0700301
302static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
303{
304 return __clocksource_register_scale(cs, 1, hz);
305}
306
307static inline int clocksource_register_khz(struct clocksource *cs, u32 khz)
308{
309 return __clocksource_register_scale(cs, 1000, khz);
310}
311
John Stultz852db462010-07-13 17:56:28 -0700312static inline void __clocksource_updatefreq_hz(struct clocksource *cs, u32 hz)
313{
314 __clocksource_updatefreq_scale(cs, 1, hz);
315}
316
317static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz)
318{
319 __clocksource_updatefreq_scale(cs, 1000, khz);
320}
John Stultzd7e81c22010-05-07 18:07:38 -0700321
john stultzacc9a9d2007-02-16 01:28:17 -0800322#ifdef CONFIG_GENERIC_TIME_VSYSCALL
Lin Ming0696b712009-11-17 13:49:50 +0800323extern void
John Stultz76158562010-07-13 17:56:23 -0700324update_vsyscall(struct timespec *ts, struct timespec *wtm,
325 struct clocksource *c, u32 mult);
Tony Breeds2c622142007-10-18 03:04:57 -0700326extern void update_vsyscall_tz(void);
john stultzacc9a9d2007-02-16 01:28:17 -0800327#else
Lin Ming0696b712009-11-17 13:49:50 +0800328static inline void
John Stultz76158562010-07-13 17:56:23 -0700329update_vsyscall(struct timespec *ts, struct timespec *wtm,
330 struct clocksource *c, u32 mult)
john stultzacc9a9d2007-02-16 01:28:17 -0800331{
332}
Tony Breeds2c622142007-10-18 03:04:57 -0700333
334static inline void update_vsyscall_tz(void)
335{
336}
john stultzacc9a9d2007-02-16 01:28:17 -0800337#endif
338
Martin Schwidefsky75c51582009-08-14 15:47:30 +0200339extern void timekeeping_notify(struct clocksource *clock);
340
Russell King442c8172011-05-08 14:06:52 +0100341extern cycle_t clocksource_mmio_readl_up(struct clocksource *);
342extern cycle_t clocksource_mmio_readl_down(struct clocksource *);
343extern cycle_t clocksource_mmio_readw_up(struct clocksource *);
344extern cycle_t clocksource_mmio_readw_down(struct clocksource *);
345
346extern int clocksource_mmio_init(void __iomem *, const char *,
347 unsigned long, int, unsigned, cycle_t (*)(struct clocksource *));
348
Russell King8c414ff2011-05-08 18:50:20 +0100349extern int clocksource_i8253_init(void);
350
john stultz734efb42006-06-26 00:25:05 -0700351#endif /* _LINUX_CLOCKSOURCE_H */