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