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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> | |
5d8b34fd | 15 | #include <linux/timer.h> |
734efb46 JS |
16 | #include <asm/div64.h> |
17 | #include <asm/io.h> | |
18 | ||
19 | /* clocksource cycle base type */ | |
20 | typedef u64 cycle_t; | |
5d8b34fd | 21 | struct clocksource; |
734efb46 JS |
22 | |
23 | /** | |
24 | * struct clocksource - hardware abstraction for a free running counter | |
25 | * Provides mostly state-free accessors to the underlying hardware. | |
26 | * | |
27 | * @name: ptr to clocksource name | |
28 | * @list: list head for registration | |
29 | * @rating: rating value for selection (higher is better) | |
30 | * To avoid rating inflation the following | |
31 | * list should give you a guide as to how | |
32 | * to assign your clocksource a rating | |
33 | * 1-99: Unfit for real use | |
34 | * Only available for bootup and testing purposes. | |
35 | * 100-199: Base level usability. | |
36 | * Functional for real use, but not desired. | |
37 | * 200-299: Good. | |
38 | * A correct and usable clocksource. | |
39 | * 300-399: Desired. | |
40 | * A reasonably fast and accurate clocksource. | |
41 | * 400-499: Perfect | |
42 | * The ideal clocksource. A must-use where | |
43 | * available. | |
44 | * @read: returns a cycle value | |
45 | * @mask: bitmask for two's complement | |
46 | * subtraction of non 64 bit counters | |
47 | * @mult: cycle to nanosecond multiplier | |
48 | * @shift: cycle to nanosecond divisor (power of two) | |
73b08d2a | 49 | * @flags: flags describing special properties |
19923c19 RZ |
50 | * @cycle_interval: Used internally by timekeeping core, please ignore. |
51 | * @xtime_interval: Used internally by timekeeping core, please ignore. | |
734efb46 JS |
52 | */ |
53 | struct clocksource { | |
54 | char *name; | |
55 | struct list_head list; | |
56 | int rating; | |
57 | cycle_t (*read)(void); | |
58 | cycle_t mask; | |
59 | u32 mult; | |
60 | u32 shift; | |
73b08d2a | 61 | unsigned long flags; |
734efb46 JS |
62 | |
63 | /* timekeeping specific data, ignore */ | |
19923c19 RZ |
64 | cycle_t cycle_last, cycle_interval; |
65 | u64 xtime_nsec, xtime_interval; | |
66 | s64 error; | |
5d8b34fd TG |
67 | |
68 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG | |
69 | /* Watchdog related data, used by the framework */ | |
70 | struct list_head wd_list; | |
71 | cycle_t wd_last; | |
72 | #endif | |
734efb46 JS |
73 | }; |
74 | ||
73b08d2a TG |
75 | /* |
76 | * Clock source flags bits:: | |
77 | */ | |
5d8b34fd TG |
78 | #define CLOCK_SOURCE_IS_CONTINUOUS 0x01 |
79 | #define CLOCK_SOURCE_MUST_VERIFY 0x02 | |
80 | ||
81 | #define CLOCK_SOURCE_WATCHDOG 0x10 | |
82 | #define CLOCK_SOURCE_VALID_FOR_HRES 0x20 | |
73b08d2a | 83 | |
7f9f303a JC |
84 | /* simplify initialization of mask field */ |
85 | #define CLOCKSOURCE_MASK(bits) (cycle_t)(bits<64 ? ((1ULL<<bits)-1) : -1) | |
734efb46 JS |
86 | |
87 | /** | |
88 | * clocksource_khz2mult - calculates mult from khz and shift | |
89 | * @khz: Clocksource frequency in KHz | |
90 | * @shift_constant: Clocksource shift factor | |
91 | * | |
92 | * Helper functions that converts a khz counter frequency to a timsource | |
93 | * multiplier, given the clocksource shift value | |
94 | */ | |
95 | static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) | |
96 | { | |
97 | /* khz = cyc/(Million ns) | |
98 | * mult/2^shift = ns/cyc | |
99 | * mult = ns/cyc * 2^shift | |
100 | * mult = 1Million/khz * 2^shift | |
101 | * mult = 1000000 * 2^shift / khz | |
102 | * mult = (1000000<<shift) / khz | |
103 | */ | |
104 | u64 tmp = ((u64)1000000) << shift_constant; | |
105 | ||
106 | tmp += khz/2; /* round for do_div */ | |
107 | do_div(tmp, khz); | |
108 | ||
109 | return (u32)tmp; | |
110 | } | |
111 | ||
112 | /** | |
113 | * clocksource_hz2mult - calculates mult from hz and shift | |
114 | * @hz: Clocksource frequency in Hz | |
115 | * @shift_constant: Clocksource shift factor | |
116 | * | |
117 | * Helper functions that converts a hz counter | |
118 | * frequency to a timsource multiplier, given the | |
119 | * clocksource shift value | |
120 | */ | |
121 | static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) | |
122 | { | |
123 | /* hz = cyc/(Billion ns) | |
124 | * mult/2^shift = ns/cyc | |
125 | * mult = ns/cyc * 2^shift | |
126 | * mult = 1Billion/hz * 2^shift | |
127 | * mult = 1000000000 * 2^shift / hz | |
128 | * mult = (1000000000<<shift) / hz | |
129 | */ | |
130 | u64 tmp = ((u64)1000000000) << shift_constant; | |
131 | ||
132 | tmp += hz/2; /* round for do_div */ | |
133 | do_div(tmp, hz); | |
134 | ||
135 | return (u32)tmp; | |
136 | } | |
137 | ||
138 | /** | |
a2752549 | 139 | * clocksource_read: - Access the clocksource's current cycle value |
734efb46 JS |
140 | * @cs: pointer to clocksource being read |
141 | * | |
142 | * Uses the clocksource to return the current cycle_t value | |
143 | */ | |
a2752549 | 144 | static inline cycle_t clocksource_read(struct clocksource *cs) |
734efb46 JS |
145 | { |
146 | return cs->read(); | |
147 | } | |
148 | ||
149 | /** | |
150 | * cyc2ns - converts clocksource cycles to nanoseconds | |
151 | * @cs: Pointer to clocksource | |
152 | * @cycles: Cycles | |
153 | * | |
154 | * Uses the clocksource and ntp ajdustment to convert cycle_ts to nanoseconds. | |
155 | * | |
156 | * XXX - This could use some mult_lxl_ll() asm optimization | |
157 | */ | |
158 | static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles) | |
159 | { | |
160 | u64 ret = (u64)cycles; | |
161 | ret = (ret * cs->mult) >> cs->shift; | |
162 | return ret; | |
163 | } | |
164 | ||
165 | /** | |
a2752549 | 166 | * clocksource_calculate_interval - Calculates a clocksource interval struct |
734efb46 JS |
167 | * |
168 | * @c: Pointer to clocksource. | |
169 | * @length_nsec: Desired interval length in nanoseconds. | |
170 | * | |
171 | * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment | |
172 | * pair and interval request. | |
173 | * | |
174 | * Unless you're the timekeeping code, you should not be using this! | |
175 | */ | |
a2752549 | 176 | static inline void clocksource_calculate_interval(struct clocksource *c, |
f5f1a24a | 177 | unsigned long length_nsec) |
734efb46 JS |
178 | { |
179 | u64 tmp; | |
180 | ||
181 | /* XXX - All of this could use a whole lot of optimization */ | |
182 | tmp = length_nsec; | |
183 | tmp <<= c->shift; | |
184 | tmp += c->mult/2; | |
185 | do_div(tmp, c->mult); | |
186 | ||
19923c19 RZ |
187 | c->cycle_interval = (cycle_t)tmp; |
188 | if (c->cycle_interval == 0) | |
189 | c->cycle_interval = 1; | |
734efb46 | 190 | |
19923c19 | 191 | c->xtime_interval = (u64)c->cycle_interval * c->mult; |
5eb6d205 JS |
192 | } |
193 | ||
194 | ||
734efb46 | 195 | /* used to install a new clocksource */ |
92c7e002 TG |
196 | extern int clocksource_register(struct clocksource*); |
197 | extern struct clocksource* clocksource_get_next(void); | |
198 | extern void clocksource_change_rating(struct clocksource *cs, int rating); | |
734efb46 JS |
199 | |
200 | #endif /* _LINUX_CLOCKSOURCE_H */ |