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734efb46 JS |
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> |
734efb46 JS |
17 | #include <asm/div64.h> |
18 | #include <asm/io.h> | |
19 | ||
20 | /* clocksource cycle base type */ | |
21 | typedef u64 cycle_t; | |
5d8b34fd | 22 | struct clocksource; |
734efb46 JS |
23 | |
24 | /** | |
25 | * struct clocksource - hardware abstraction for a free running counter | |
26 | * Provides mostly state-free accessors to the underlying hardware. | |
27 | * | |
28 | * @name: ptr to clocksource name | |
29 | * @list: list head for registration | |
30 | * @rating: rating value for selection (higher is better) | |
31 | * To avoid rating inflation the following | |
32 | * list should give you a guide as to how | |
33 | * to assign your clocksource a rating | |
34 | * 1-99: Unfit for real use | |
35 | * Only available for bootup and testing purposes. | |
36 | * 100-199: Base level usability. | |
37 | * Functional for real use, but not desired. | |
38 | * 200-299: Good. | |
39 | * A correct and usable clocksource. | |
40 | * 300-399: Desired. | |
41 | * A reasonably fast and accurate clocksource. | |
42 | * 400-499: Perfect | |
43 | * The ideal clocksource. A must-use where | |
44 | * available. | |
45 | * @read: returns a cycle value | |
46 | * @mask: bitmask for two's complement | |
47 | * subtraction of non 64 bit counters | |
48 | * @mult: cycle to nanosecond multiplier | |
49 | * @shift: cycle to nanosecond divisor (power of two) | |
73b08d2a | 50 | * @flags: flags describing special properties |
acc9a9dc | 51 | * @vread: vsyscall based read |
b52f52a0 | 52 | * @resume: resume function for the clocksource, if necessary |
19923c19 RZ |
53 | * @cycle_interval: Used internally by timekeeping core, please ignore. |
54 | * @xtime_interval: Used internally by timekeeping core, please ignore. | |
734efb46 JS |
55 | */ |
56 | struct clocksource { | |
329c8d84 ED |
57 | /* |
58 | * First part of structure is read mostly | |
59 | */ | |
734efb46 JS |
60 | char *name; |
61 | struct list_head list; | |
62 | int rating; | |
63 | cycle_t (*read)(void); | |
64 | cycle_t mask; | |
65 | u32 mult; | |
66 | u32 shift; | |
73b08d2a | 67 | unsigned long flags; |
acc9a9dc | 68 | cycle_t (*vread)(void); |
b52f52a0 | 69 | void (*resume)(void); |
0aa366f3 TL |
70 | #ifdef CONFIG_IA64 |
71 | void *fsys_mmio; /* used by fsyscall asm code */ | |
72 | #define CLKSRC_FSYS_MMIO_SET(mmio, addr) ((mmio) = (addr)) | |
73 | #else | |
74 | #define CLKSRC_FSYS_MMIO_SET(mmio, addr) do { } while (0) | |
75 | #endif | |
734efb46 JS |
76 | |
77 | /* timekeeping specific data, ignore */ | |
329c8d84 ED |
78 | cycle_t cycle_interval; |
79 | u64 xtime_interval; | |
80 | /* | |
81 | * Second part is written at each timer interrupt | |
82 | * Keep it in a different cache line to dirty no | |
83 | * more than one cache line. | |
84 | */ | |
85 | cycle_t cycle_last ____cacheline_aligned_in_smp; | |
86 | u64 xtime_nsec; | |
19923c19 | 87 | s64 error; |
5d8b34fd TG |
88 | |
89 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG | |
90 | /* Watchdog related data, used by the framework */ | |
91 | struct list_head wd_list; | |
92 | cycle_t wd_last; | |
93 | #endif | |
734efb46 JS |
94 | }; |
95 | ||
7dffa3c6 RZ |
96 | extern struct clocksource *clock; /* current clocksource */ |
97 | ||
73b08d2a TG |
98 | /* |
99 | * Clock source flags bits:: | |
100 | */ | |
5d8b34fd TG |
101 | #define CLOCK_SOURCE_IS_CONTINUOUS 0x01 |
102 | #define CLOCK_SOURCE_MUST_VERIFY 0x02 | |
103 | ||
104 | #define CLOCK_SOURCE_WATCHDOG 0x10 | |
105 | #define CLOCK_SOURCE_VALID_FOR_HRES 0x20 | |
73b08d2a | 106 | |
7f9f303a | 107 | /* simplify initialization of mask field */ |
1d76c262 | 108 | #define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1) |
734efb46 JS |
109 | |
110 | /** | |
111 | * clocksource_khz2mult - calculates mult from khz and shift | |
112 | * @khz: Clocksource frequency in KHz | |
113 | * @shift_constant: Clocksource shift factor | |
114 | * | |
115 | * Helper functions that converts a khz counter frequency to a timsource | |
116 | * multiplier, given the clocksource shift value | |
117 | */ | |
118 | static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) | |
119 | { | |
120 | /* khz = cyc/(Million ns) | |
121 | * mult/2^shift = ns/cyc | |
122 | * mult = ns/cyc * 2^shift | |
123 | * mult = 1Million/khz * 2^shift | |
124 | * mult = 1000000 * 2^shift / khz | |
125 | * mult = (1000000<<shift) / khz | |
126 | */ | |
127 | u64 tmp = ((u64)1000000) << shift_constant; | |
128 | ||
129 | tmp += khz/2; /* round for do_div */ | |
130 | do_div(tmp, khz); | |
131 | ||
132 | return (u32)tmp; | |
133 | } | |
134 | ||
135 | /** | |
136 | * clocksource_hz2mult - calculates mult from hz and shift | |
137 | * @hz: Clocksource frequency in Hz | |
138 | * @shift_constant: Clocksource shift factor | |
139 | * | |
140 | * Helper functions that converts a hz counter | |
141 | * frequency to a timsource multiplier, given the | |
142 | * clocksource shift value | |
143 | */ | |
144 | static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) | |
145 | { | |
146 | /* hz = cyc/(Billion ns) | |
147 | * mult/2^shift = ns/cyc | |
148 | * mult = ns/cyc * 2^shift | |
149 | * mult = 1Billion/hz * 2^shift | |
150 | * mult = 1000000000 * 2^shift / hz | |
151 | * mult = (1000000000<<shift) / hz | |
152 | */ | |
153 | u64 tmp = ((u64)1000000000) << shift_constant; | |
154 | ||
155 | tmp += hz/2; /* round for do_div */ | |
156 | do_div(tmp, hz); | |
157 | ||
158 | return (u32)tmp; | |
159 | } | |
160 | ||
161 | /** | |
a2752549 | 162 | * clocksource_read: - Access the clocksource's current cycle value |
734efb46 JS |
163 | * @cs: pointer to clocksource being read |
164 | * | |
165 | * Uses the clocksource to return the current cycle_t value | |
166 | */ | |
a2752549 | 167 | static inline cycle_t clocksource_read(struct clocksource *cs) |
734efb46 JS |
168 | { |
169 | return cs->read(); | |
170 | } | |
171 | ||
172 | /** | |
173 | * cyc2ns - converts clocksource cycles to nanoseconds | |
174 | * @cs: Pointer to clocksource | |
175 | * @cycles: Cycles | |
176 | * | |
177 | * Uses the clocksource and ntp ajdustment to convert cycle_ts to nanoseconds. | |
178 | * | |
179 | * XXX - This could use some mult_lxl_ll() asm optimization | |
180 | */ | |
181 | static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles) | |
182 | { | |
183 | u64 ret = (u64)cycles; | |
184 | ret = (ret * cs->mult) >> cs->shift; | |
185 | return ret; | |
186 | } | |
187 | ||
188 | /** | |
a2752549 | 189 | * clocksource_calculate_interval - Calculates a clocksource interval struct |
734efb46 JS |
190 | * |
191 | * @c: Pointer to clocksource. | |
192 | * @length_nsec: Desired interval length in nanoseconds. | |
193 | * | |
194 | * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment | |
195 | * pair and interval request. | |
196 | * | |
197 | * Unless you're the timekeeping code, you should not be using this! | |
198 | */ | |
a2752549 | 199 | static inline void clocksource_calculate_interval(struct clocksource *c, |
f5f1a24a | 200 | unsigned long length_nsec) |
734efb46 JS |
201 | { |
202 | u64 tmp; | |
203 | ||
204 | /* XXX - All of this could use a whole lot of optimization */ | |
205 | tmp = length_nsec; | |
206 | tmp <<= c->shift; | |
207 | tmp += c->mult/2; | |
208 | do_div(tmp, c->mult); | |
209 | ||
19923c19 RZ |
210 | c->cycle_interval = (cycle_t)tmp; |
211 | if (c->cycle_interval == 0) | |
212 | c->cycle_interval = 1; | |
734efb46 | 213 | |
19923c19 | 214 | c->xtime_interval = (u64)c->cycle_interval * c->mult; |
5eb6d205 JS |
215 | } |
216 | ||
217 | ||
734efb46 | 218 | /* used to install a new clocksource */ |
92c7e002 | 219 | extern int clocksource_register(struct clocksource*); |
4713e22c | 220 | extern void clocksource_unregister(struct clocksource*); |
7c3078b6 | 221 | extern void clocksource_touch_watchdog(void); |
92c7e002 TG |
222 | extern struct clocksource* clocksource_get_next(void); |
223 | extern void clocksource_change_rating(struct clocksource *cs, int rating); | |
b52f52a0 | 224 | extern void clocksource_resume(void); |
734efb46 | 225 | |
acc9a9dc JS |
226 | #ifdef CONFIG_GENERIC_TIME_VSYSCALL |
227 | extern void update_vsyscall(struct timespec *ts, struct clocksource *c); | |
2c622148 | 228 | extern void update_vsyscall_tz(void); |
acc9a9dc JS |
229 | #else |
230 | static inline void update_vsyscall(struct timespec *ts, struct clocksource *c) | |
231 | { | |
232 | } | |
2c622148 TB |
233 | |
234 | static inline void update_vsyscall_tz(void) | |
235 | { | |
236 | } | |
acc9a9dc JS |
237 | #endif |
238 | ||
734efb46 | 239 | #endif /* _LINUX_CLOCKSOURCE_H */ |