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1 : /* SPDX-License-Identifier: GPL-2.0 */
2 : /* linux/include/linux/clocksource.h
3 : *
4 : * This file contains the structure definitions for clocksources.
5 : *
6 : * If you are not a clocksource, or timekeeping code, you should
7 : * not be including this file!
8 : */
9 : #ifndef _LINUX_CLOCKSOURCE_H
10 : #define _LINUX_CLOCKSOURCE_H
11 :
12 : #include <linux/types.h>
13 : #include <linux/timex.h>
14 : #include <linux/time.h>
15 : #include <linux/list.h>
16 : #include <linux/cache.h>
17 : #include <linux/timer.h>
18 : #include <linux/init.h>
19 : #include <linux/of.h>
20 : #include <asm/div64.h>
21 : #include <asm/io.h>
22 :
23 : struct clocksource;
24 : struct module;
25 :
26 : #if defined(CONFIG_ARCH_CLOCKSOURCE_DATA) || \
27 : defined(CONFIG_GENERIC_GETTIMEOFDAY)
28 : #include <asm/clocksource.h>
29 : #endif
30 :
31 : #include <vdso/clocksource.h>
32 :
33 : /**
34 : * struct clocksource - hardware abstraction for a free running counter
35 : * Provides mostly state-free accessors to the underlying hardware.
36 : * This is the structure used for system time.
37 : *
38 : * @read: Returns a cycle value, passes clocksource as argument
39 : * @mask: Bitmask for two's complement
40 : * subtraction of non 64 bit counters
41 : * @mult: Cycle to nanosecond multiplier
42 : * @shift: Cycle to nanosecond divisor (power of two)
43 : * @max_idle_ns: Maximum idle time permitted by the clocksource (nsecs)
44 : * @maxadj: Maximum adjustment value to mult (~11%)
45 : * @archdata: Optional arch-specific data
46 : * @max_cycles: Maximum safe cycle value which won't overflow on
47 : * multiplication
48 : * @name: Pointer to clocksource name
49 : * @list: List head for registration (internal)
50 : * @rating: Rating value for selection (higher is better)
51 : * To avoid rating inflation the following
52 : * list should give you a guide as to how
53 : * to assign your clocksource a rating
54 : * 1-99: Unfit for real use
55 : * Only available for bootup and testing purposes.
56 : * 100-199: Base level usability.
57 : * Functional for real use, but not desired.
58 : * 200-299: Good.
59 : * A correct and usable clocksource.
60 : * 300-399: Desired.
61 : * A reasonably fast and accurate clocksource.
62 : * 400-499: Perfect
63 : * The ideal clocksource. A must-use where
64 : * available.
65 : * @flags: Flags describing special properties
66 : * @enable: Optional function to enable the clocksource
67 : * @disable: Optional function to disable the clocksource
68 : * @suspend: Optional suspend function for the clocksource
69 : * @resume: Optional resume function for the clocksource
70 : * @mark_unstable: Optional function to inform the clocksource driver that
71 : * the watchdog marked the clocksource unstable
72 : * @tick_stable: Optional function called periodically from the watchdog
73 : * code to provide stable syncrhonization points
74 : * @wd_list: List head to enqueue into the watchdog list (internal)
75 : * @cs_last: Last clocksource value for clocksource watchdog
76 : * @wd_last: Last watchdog value corresponding to @cs_last
77 : * @owner: Module reference, must be set by clocksource in modules
78 : *
79 : * Note: This struct is not used in hotpathes of the timekeeping code
80 : * because the timekeeper caches the hot path fields in its own data
81 : * structure, so no cache line alignment is required,
82 : *
83 : * The pointer to the clocksource itself is handed to the read
84 : * callback. If you need extra information there you can wrap struct
85 : * clocksource into your own struct. Depending on the amount of
86 : * information you need you should consider to cache line align that
87 : * structure.
88 : */
89 : struct clocksource {
90 : u64 (*read)(struct clocksource *cs);
91 : u64 mask;
92 : u32 mult;
93 : u32 shift;
94 : u64 max_idle_ns;
95 : u32 maxadj;
96 : #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
97 : struct arch_clocksource_data archdata;
98 : #endif
99 : u64 max_cycles;
100 : const char *name;
101 : struct list_head list;
102 : int rating;
103 : enum vdso_clock_mode vdso_clock_mode;
104 : unsigned long flags;
105 :
106 : int (*enable)(struct clocksource *cs);
107 : void (*disable)(struct clocksource *cs);
108 : void (*suspend)(struct clocksource *cs);
109 : void (*resume)(struct clocksource *cs);
110 : void (*mark_unstable)(struct clocksource *cs);
111 : void (*tick_stable)(struct clocksource *cs);
112 :
113 : /* private: */
114 : #ifdef CONFIG_CLOCKSOURCE_WATCHDOG
115 : /* Watchdog related data, used by the framework */
116 : struct list_head wd_list;
117 : u64 cs_last;
118 : u64 wd_last;
119 : #endif
120 : struct module *owner;
121 : };
122 :
123 : /*
124 : * Clock source flags bits::
125 : */
126 : #define CLOCK_SOURCE_IS_CONTINUOUS 0x01
127 : #define CLOCK_SOURCE_MUST_VERIFY 0x02
128 :
129 : #define CLOCK_SOURCE_WATCHDOG 0x10
130 : #define CLOCK_SOURCE_VALID_FOR_HRES 0x20
131 : #define CLOCK_SOURCE_UNSTABLE 0x40
132 : #define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80
133 : #define CLOCK_SOURCE_RESELECT 0x100
134 :
135 : /* simplify initialization of mask field */
136 : #define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0)
137 :
138 : static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from)
139 : {
140 : /* freq = cyc/from
141 : * mult/2^shift = ns/cyc
142 : * mult = ns/cyc * 2^shift
143 : * mult = from/freq * 2^shift
144 : * mult = from * 2^shift / freq
145 : * mult = (from<<shift) / freq
146 : */
147 : u64 tmp = ((u64)from) << shift_constant;
148 :
149 : tmp += freq/2; /* round for do_div */
150 : do_div(tmp, freq);
151 :
152 : return (u32)tmp;
153 : }
154 :
155 : /**
156 : * clocksource_khz2mult - calculates mult from khz and shift
157 : * @khz: Clocksource frequency in KHz
158 : * @shift_constant: Clocksource shift factor
159 : *
160 : * Helper functions that converts a khz counter frequency to a timsource
161 : * multiplier, given the clocksource shift value
162 : */
163 : static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
164 : {
165 : return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC);
166 : }
167 :
168 : /**
169 : * clocksource_hz2mult - calculates mult from hz and shift
170 : * @hz: Clocksource frequency in Hz
171 : * @shift_constant: Clocksource shift factor
172 : *
173 : * Helper functions that converts a hz counter
174 : * frequency to a timsource multiplier, given the
175 : * clocksource shift value
176 : */
177 : static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
178 : {
179 : return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC);
180 : }
181 :
182 : /**
183 : * clocksource_cyc2ns - converts clocksource cycles to nanoseconds
184 : * @cycles: cycles
185 : * @mult: cycle to nanosecond multiplier
186 : * @shift: cycle to nanosecond divisor (power of two)
187 : *
188 : * Converts clocksource cycles to nanoseconds, using the given @mult and @shift.
189 : * The code is optimized for performance and is not intended to work
190 : * with absolute clocksource cycles (as those will easily overflow),
191 : * but is only intended to be used with relative (delta) clocksource cycles.
192 : *
193 : * XXX - This could use some mult_lxl_ll() asm optimization
194 : */
195 141 : static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift)
196 : {
197 73 : return ((u64) cycles * mult) >> shift;
198 : }
199 :
200 :
201 : extern int clocksource_unregister(struct clocksource*);
202 : extern void clocksource_touch_watchdog(void);
203 : extern void clocksource_change_rating(struct clocksource *cs, int rating);
204 : extern void clocksource_suspend(void);
205 : extern void clocksource_resume(void);
206 : extern struct clocksource * __init clocksource_default_clock(void);
207 : extern void clocksource_mark_unstable(struct clocksource *cs);
208 : extern void
209 : clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles);
210 : extern u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 now);
211 :
212 : extern u64
213 : clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
214 : extern void
215 : clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
216 :
217 : /*
218 : * Don't call __clocksource_register_scale directly, use
219 : * clocksource_register_hz/khz
220 : */
221 : extern int
222 : __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
223 : extern void
224 : __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq);
225 :
226 : /*
227 : * Don't call this unless you are a default clocksource
228 : * (AKA: jiffies) and absolutely have to.
229 : */
230 2 : static inline int __clocksource_register(struct clocksource *cs)
231 : {
232 2 : return __clocksource_register_scale(cs, 1, 0);
233 : }
234 :
235 1 : static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
236 : {
237 1 : return __clocksource_register_scale(cs, 1, hz);
238 : }
239 :
240 2 : static inline int clocksource_register_khz(struct clocksource *cs, u32 khz)
241 : {
242 2 : return __clocksource_register_scale(cs, 1000, khz);
243 : }
244 :
245 : static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz)
246 : {
247 : __clocksource_update_freq_scale(cs, 1, hz);
248 : }
249 :
250 : static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz)
251 : {
252 : __clocksource_update_freq_scale(cs, 1000, khz);
253 : }
254 :
255 : #ifdef CONFIG_ARCH_CLOCKSOURCE_INIT
256 : extern void clocksource_arch_init(struct clocksource *cs);
257 : #else
258 : static inline void clocksource_arch_init(struct clocksource *cs) { }
259 : #endif
260 :
261 : extern int timekeeping_notify(struct clocksource *clock);
262 :
263 : extern u64 clocksource_mmio_readl_up(struct clocksource *);
264 : extern u64 clocksource_mmio_readl_down(struct clocksource *);
265 : extern u64 clocksource_mmio_readw_up(struct clocksource *);
266 : extern u64 clocksource_mmio_readw_down(struct clocksource *);
267 :
268 : extern int clocksource_mmio_init(void __iomem *, const char *,
269 : unsigned long, int, unsigned, u64 (*)(struct clocksource *));
270 :
271 : extern int clocksource_i8253_init(void);
272 :
273 : #define TIMER_OF_DECLARE(name, compat, fn) \
274 : OF_DECLARE_1_RET(timer, name, compat, fn)
275 :
276 : #ifdef CONFIG_TIMER_PROBE
277 : extern void timer_probe(void);
278 : #else
279 : static inline void timer_probe(void) {}
280 : #endif
281 :
282 : #define TIMER_ACPI_DECLARE(name, table_id, fn) \
283 : ACPI_DECLARE_PROBE_ENTRY(timer, name, table_id, 0, NULL, 0, fn)
284 :
285 : #endif /* _LINUX_CLOCKSOURCE_H */
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