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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
23struct clocksource;
24struct 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 */
89struct 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
138static 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 */
163static 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 */
177static 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 */
195static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift)
196{
197 return ((u64) cycles * mult) >> shift;
198}
199
200
201extern int clocksource_unregister(struct clocksource*);
202extern void clocksource_touch_watchdog(void);
203extern void clocksource_change_rating(struct clocksource *cs, int rating);
204extern void clocksource_suspend(void);
205extern void clocksource_resume(void);
206extern struct clocksource * __init clocksource_default_clock(void);
207extern void clocksource_mark_unstable(struct clocksource *cs);
208extern void
209clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles);
210extern u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 now);
211
212extern u64
213clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
214extern void
215clocks_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 */
221extern int
222__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
223extern 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 */
230static inline int __clocksource_register(struct clocksource *cs)
231{
232 return __clocksource_register_scale(cs, 1, 0);
233}
234
235static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
236{
237 return __clocksource_register_scale(cs, 1, hz);
238}
239
240static inline int clocksource_register_khz(struct clocksource *cs, u32 khz)
241{
242 return __clocksource_register_scale(cs, 1000, khz);
243}
244
245static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz)
246{
247 __clocksource_update_freq_scale(cs, 1, hz);
248}
249
250static 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
256extern void clocksource_arch_init(struct clocksource *cs);
257#else
258static inline void clocksource_arch_init(struct clocksource *cs) { }
259#endif
260
261extern int timekeeping_notify(struct clocksource *clock);
262
263extern u64 clocksource_mmio_readl_up(struct clocksource *);
264extern u64 clocksource_mmio_readl_down(struct clocksource *);
265extern u64 clocksource_mmio_readw_up(struct clocksource *);
266extern u64 clocksource_mmio_readw_down(struct clocksource *);
267
268extern int clocksource_mmio_init(void __iomem *, const char *,
269 unsigned long, int, unsigned, u64 (*)(struct clocksource *));
270
271extern 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
277extern void timer_probe(void);
278#else
279static 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 */