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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 <linux/clocksource_ids.h>
21#include <asm/div64.h>
22#include <asm/io.h>
23
24struct clocksource_base;
25struct clocksource;
26struct module;
27
28#if defined(CONFIG_GENERIC_GETTIMEOFDAY)
29#include <asm/clocksource.h>
30#endif
31
32#include <vdso/clocksource.h>
33
34/**
35 * struct clocksource - hardware abstraction for a free running counter
36 * Provides mostly state-free accessors to the underlying hardware.
37 * This is the structure used for system time.
38 *
39 * @read: Returns a cycle value, passes clocksource as argument
40 * @mask: Bitmask for two's complement
41 * subtraction of non 64 bit counters
42 * @mult: Cycle to nanosecond multiplier
43 * @shift: Cycle to nanosecond divisor (power of two)
44 * @max_idle_ns: Maximum idle time permitted by the clocksource (nsecs)
45 * @maxadj: Maximum adjustment value to mult (~11%)
46 * @archdata: Optional arch-specific data
47 * @max_cycles: Maximum safe cycle value which won't overflow on
48 * multiplication
49 * @max_raw_delta: Maximum safe delta value for negative motion detection
50 * @name: Pointer to clocksource name
51 * @list: List head for registration (internal)
52 * @freq_khz: Clocksource frequency in khz.
53 * @rating: Rating value for selection (higher is better)
54 * To avoid rating inflation the following
55 * list should give you a guide as to how
56 * to assign your clocksource a rating
57 * 1-99: Unfit for real use
58 * Only available for bootup and testing purposes.
59 * 100-199: Base level usability.
60 * Functional for real use, but not desired.
61 * 200-299: Good.
62 * A correct and usable clocksource.
63 * 300-399: Desired.
64 * A reasonably fast and accurate clocksource.
65 * 400-499: Perfect
66 * The ideal clocksource. A must-use where
67 * available.
68 * @id: Defaults to CSID_GENERIC. The id value is captured
69 * in certain snapshot functions to allow callers to
70 * validate the clocksource from which the snapshot was
71 * taken.
72 * @flags: Flags describing special properties
73 * @base: Hardware abstraction for clock on which a clocksource
74 * is based
75 * @enable: Optional function to enable the clocksource
76 * @disable: Optional function to disable the clocksource
77 * @suspend: Optional suspend function for the clocksource
78 * @resume: Optional resume function for the clocksource
79 * @mark_unstable: Optional function to inform the clocksource driver that
80 * the watchdog marked the clocksource unstable
81 * @tick_stable: Optional function called periodically from the watchdog
82 * code to provide stable synchronization points
83 * @wd_list: List head to enqueue into the watchdog list (internal)
84 * @cs_last: Last clocksource value for clocksource watchdog
85 * @wd_last: Last watchdog value corresponding to @cs_last
86 * @owner: Module reference, must be set by clocksource in modules
87 *
88 * Note: This struct is not used in hotpathes of the timekeeping code
89 * because the timekeeper caches the hot path fields in its own data
90 * structure, so no cache line alignment is required,
91 *
92 * The pointer to the clocksource itself is handed to the read
93 * callback. If you need extra information there you can wrap struct
94 * clocksource into your own struct. Depending on the amount of
95 * information you need you should consider to cache line align that
96 * structure.
97 */
98struct clocksource {
99 u64 (*read)(struct clocksource *cs);
100 u64 mask;
101 u32 mult;
102 u32 shift;
103 u64 max_idle_ns;
104 u32 maxadj;
105 u64 max_cycles;
106 u64 max_raw_delta;
107 const char *name;
108 struct list_head list;
109 u32 freq_khz;
110 int rating;
111 enum clocksource_ids id;
112 enum vdso_clock_mode vdso_clock_mode;
113 unsigned long flags;
114 struct clocksource_base *base;
115
116 int (*enable)(struct clocksource *cs);
117 void (*disable)(struct clocksource *cs);
118 void (*suspend)(struct clocksource *cs);
119 void (*resume)(struct clocksource *cs);
120 void (*mark_unstable)(struct clocksource *cs);
121 void (*tick_stable)(struct clocksource *cs);
122
123 /* private: */
124#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
125 /* Watchdog related data, used by the framework */
126 struct list_head wd_list;
127 u64 cs_last;
128 u64 wd_last;
129 unsigned int wd_cpu;
130#endif
131 struct module *owner;
132};
133
134/*
135 * Clock source flags bits::
136 */
137#define CLOCK_SOURCE_IS_CONTINUOUS 0x01
138#define CLOCK_SOURCE_MUST_VERIFY 0x02
139#define CLOCK_SOURCE_CALIBRATED 0x04
140
141#define CLOCK_SOURCE_WATCHDOG 0x10
142#define CLOCK_SOURCE_VALID_FOR_HRES 0x20
143#define CLOCK_SOURCE_UNSTABLE 0x40
144#define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80
145#define CLOCK_SOURCE_RESELECT 0x100
146#define CLOCK_SOURCE_CAN_INLINE_READ 0x200
147#define CLOCK_SOURCE_HAS_COUPLED_CLOCK_EVENT 0x400
148
149#define CLOCK_SOURCE_WDTEST 0x800
150#define CLOCK_SOURCE_WDTEST_PERCPU 0x1000
151
152/* simplify initialization of mask field */
153#define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0)
154
155static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from)
156{
157 /* freq = cyc/from
158 * mult/2^shift = ns/cyc
159 * mult = ns/cyc * 2^shift
160 * mult = from/freq * 2^shift
161 * mult = from * 2^shift / freq
162 * mult = (from<<shift) / freq
163 */
164 u64 tmp = ((u64)from) << shift_constant;
165
166 tmp += freq/2; /* round for do_div */
167 do_div(tmp, freq);
168
169 return (u32)tmp;
170}
171
172/**
173 * clocksource_khz2mult - calculates mult from khz and shift
174 * @khz: Clocksource frequency in KHz
175 * @shift_constant: Clocksource shift factor
176 *
177 * Helper functions that converts a khz counter frequency to a timsource
178 * multiplier, given the clocksource shift value
179 */
180static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
181{
182 return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC);
183}
184
185/**
186 * clocksource_hz2mult - calculates mult from hz and shift
187 * @hz: Clocksource frequency in Hz
188 * @shift_constant: Clocksource shift factor
189 *
190 * Helper functions that converts a hz counter
191 * frequency to a timsource multiplier, given the
192 * clocksource shift value
193 */
194static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
195{
196 return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC);
197}
198
199/**
200 * clocksource_cyc2ns - converts clocksource cycles to nanoseconds
201 * @cycles: cycles
202 * @mult: cycle to nanosecond multiplier
203 * @shift: cycle to nanosecond divisor (power of two)
204 *
205 * Converts clocksource cycles to nanoseconds, using the given @mult and @shift.
206 * The code is optimized for performance and is not intended to work
207 * with absolute clocksource cycles (as those will easily overflow),
208 * but is only intended to be used with relative (delta) clocksource cycles.
209 *
210 * XXX - This could use some mult_lxl_ll() asm optimization
211 */
212static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift)
213{
214 return ((u64) cycles * mult) >> shift;
215}
216
217
218extern int clocksource_unregister(struct clocksource*);
219extern void clocksource_touch_watchdog(void);
220extern void clocksource_suspend(void);
221extern void clocksource_resume(void);
222extern struct clocksource * __init clocksource_default_clock(void);
223extern void clocksource_mark_unstable(struct clocksource *cs);
224extern void
225clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles);
226extern u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 now);
227
228extern u64
229clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
230extern void
231clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
232
233/*
234 * Don't call __clocksource_register_scale directly, use
235 * clocksource_register_hz/khz
236 */
237extern int
238__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
239extern void
240__clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq);
241
242/*
243 * Don't call this unless you are a default clocksource
244 * (AKA: jiffies) and absolutely have to.
245 */
246static inline int __clocksource_register(struct clocksource *cs)
247{
248 return __clocksource_register_scale(cs, 1, 0);
249}
250
251static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
252{
253 return __clocksource_register_scale(cs, 1, hz);
254}
255
256static inline int clocksource_register_khz(struct clocksource *cs, u32 khz)
257{
258 return __clocksource_register_scale(cs, 1000, khz);
259}
260
261static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz)
262{
263 __clocksource_update_freq_scale(cs, 1, hz);
264}
265
266static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz)
267{
268 __clocksource_update_freq_scale(cs, 1000, khz);
269}
270
271#ifdef CONFIG_ARCH_CLOCKSOURCE_INIT
272extern void clocksource_arch_init(struct clocksource *cs);
273#else
274static inline void clocksource_arch_init(struct clocksource *cs) { }
275#endif
276
277extern int timekeeping_notify(struct clocksource *clock);
278
279extern u64 clocksource_mmio_readl_up(struct clocksource *);
280extern u64 clocksource_mmio_readl_down(struct clocksource *);
281extern u64 clocksource_mmio_readw_up(struct clocksource *);
282extern u64 clocksource_mmio_readw_down(struct clocksource *);
283
284extern int clocksource_mmio_init(void __iomem *, const char *,
285 unsigned long, int, unsigned, u64 (*)(struct clocksource *));
286
287extern int clocksource_i8253_init(void);
288
289#define TIMER_OF_DECLARE(name, compat, fn) \
290 OF_DECLARE_1_RET(timer, name, compat, fn)
291
292#ifdef CONFIG_TIMER_PROBE
293extern void timer_probe(void);
294#else
295static inline void timer_probe(void) {}
296#endif
297
298#define TIMER_ACPI_DECLARE(name, table_id, fn) \
299 ACPI_DECLARE_PROBE_ENTRY(timer, name, table_id, 0, NULL, 0, fn)
300
301/**
302 * struct clocksource_base - hardware abstraction for clock on which a clocksource
303 * is based
304 * @id: Defaults to CSID_GENERIC. The id value is used for conversion
305 * functions which require that the current clocksource is based
306 * on a clocksource_base with a particular ID in certain snapshot
307 * functions to allow callers to validate the clocksource from
308 * which the snapshot was taken.
309 * @freq_khz: Nominal frequency of the base clock in kHz
310 * @offset: Offset between the base clock and the clocksource
311 * @numerator: Numerator of the clock ratio between base clock and the clocksource
312 * @denominator: Denominator of the clock ratio between base clock and the clocksource
313 */
314struct clocksource_base {
315 enum clocksource_ids id;
316 u32 freq_khz;
317 u64 offset;
318 u32 numerator;
319 u32 denominator;
320};
321
322#endif /* _LINUX_CLOCKSOURCE_H */