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 | |
24 | struct clocksource; |
25 | struct 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 | * @uncertainty_margin: Maximum uncertainty in nanoseconds per half second. |
47 | * Zero says to use default WATCHDOG_THRESHOLD. |
48 | * @archdata: Optional arch-specific data |
49 | * @max_cycles: Maximum safe cycle value which won't overflow on |
50 | * multiplication |
51 | * @name: Pointer to clocksource name |
52 | * @list: List head for registration (internal) |
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 | * @enable: Optional function to enable the clocksource |
74 | * @disable: Optional function to disable the clocksource |
75 | * @suspend: Optional suspend function for the clocksource |
76 | * @resume: Optional resume function for the clocksource |
77 | * @mark_unstable: Optional function to inform the clocksource driver that |
78 | * the watchdog marked the clocksource unstable |
79 | * @tick_stable: Optional function called periodically from the watchdog |
80 | * code to provide stable synchronization points |
81 | * @wd_list: List head to enqueue into the watchdog list (internal) |
82 | * @cs_last: Last clocksource value for clocksource watchdog |
83 | * @wd_last: Last watchdog value corresponding to @cs_last |
84 | * @owner: Module reference, must be set by clocksource in modules |
85 | * |
86 | * Note: This struct is not used in hotpathes of the timekeeping code |
87 | * because the timekeeper caches the hot path fields in its own data |
88 | * structure, so no cache line alignment is required, |
89 | * |
90 | * The pointer to the clocksource itself is handed to the read |
91 | * callback. If you need extra information there you can wrap struct |
92 | * clocksource into your own struct. Depending on the amount of |
93 | * information you need you should consider to cache line align that |
94 | * structure. |
95 | */ |
96 | struct clocksource { |
97 | u64 (*read)(struct clocksource *cs); |
98 | u64 mask; |
99 | u32 mult; |
100 | u32 shift; |
101 | u64 max_idle_ns; |
102 | u32 maxadj; |
103 | u32 uncertainty_margin; |
104 | #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA |
105 | struct arch_clocksource_data archdata; |
106 | #endif |
107 | u64 max_cycles; |
108 | const char *name; |
109 | struct list_head list; |
110 | int rating; |
111 | enum clocksource_ids id; |
112 | enum vdso_clock_mode vdso_clock_mode; |
113 | unsigned long flags; |
114 | |
115 | int (*enable)(struct clocksource *cs); |
116 | void (*disable)(struct clocksource *cs); |
117 | void (*suspend)(struct clocksource *cs); |
118 | void (*resume)(struct clocksource *cs); |
119 | void (*mark_unstable)(struct clocksource *cs); |
120 | void (*tick_stable)(struct clocksource *cs); |
121 | |
122 | /* private: */ |
123 | #ifdef CONFIG_CLOCKSOURCE_WATCHDOG |
124 | /* Watchdog related data, used by the framework */ |
125 | struct list_head wd_list; |
126 | u64 cs_last; |
127 | u64 wd_last; |
128 | #endif |
129 | struct module *owner; |
130 | }; |
131 | |
132 | /* |
133 | * Clock source flags bits:: |
134 | */ |
135 | #define CLOCK_SOURCE_IS_CONTINUOUS 0x01 |
136 | #define CLOCK_SOURCE_MUST_VERIFY 0x02 |
137 | |
138 | #define CLOCK_SOURCE_WATCHDOG 0x10 |
139 | #define CLOCK_SOURCE_VALID_FOR_HRES 0x20 |
140 | #define CLOCK_SOURCE_UNSTABLE 0x40 |
141 | #define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80 |
142 | #define CLOCK_SOURCE_RESELECT 0x100 |
143 | #define CLOCK_SOURCE_VERIFY_PERCPU 0x200 |
144 | /* simplify initialization of mask field */ |
145 | #define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0) |
146 | |
147 | static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from) |
148 | { |
149 | /* freq = cyc/from |
150 | * mult/2^shift = ns/cyc |
151 | * mult = ns/cyc * 2^shift |
152 | * mult = from/freq * 2^shift |
153 | * mult = from * 2^shift / freq |
154 | * mult = (from<<shift) / freq |
155 | */ |
156 | u64 tmp = ((u64)from) << shift_constant; |
157 | |
158 | tmp += freq/2; /* round for do_div */ |
159 | do_div(tmp, freq); |
160 | |
161 | return (u32)tmp; |
162 | } |
163 | |
164 | /** |
165 | * clocksource_khz2mult - calculates mult from khz and shift |
166 | * @khz: Clocksource frequency in KHz |
167 | * @shift_constant: Clocksource shift factor |
168 | * |
169 | * Helper functions that converts a khz counter frequency to a timsource |
170 | * multiplier, given the clocksource shift value |
171 | */ |
172 | static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) |
173 | { |
174 | return clocksource_freq2mult(freq: khz, shift_constant, NSEC_PER_MSEC); |
175 | } |
176 | |
177 | /** |
178 | * clocksource_hz2mult - calculates mult from hz and shift |
179 | * @hz: Clocksource frequency in Hz |
180 | * @shift_constant: Clocksource shift factor |
181 | * |
182 | * Helper functions that converts a hz counter |
183 | * frequency to a timsource multiplier, given the |
184 | * clocksource shift value |
185 | */ |
186 | static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) |
187 | { |
188 | return clocksource_freq2mult(freq: hz, shift_constant, NSEC_PER_SEC); |
189 | } |
190 | |
191 | /** |
192 | * clocksource_cyc2ns - converts clocksource cycles to nanoseconds |
193 | * @cycles: cycles |
194 | * @mult: cycle to nanosecond multiplier |
195 | * @shift: cycle to nanosecond divisor (power of two) |
196 | * |
197 | * Converts clocksource cycles to nanoseconds, using the given @mult and @shift. |
198 | * The code is optimized for performance and is not intended to work |
199 | * with absolute clocksource cycles (as those will easily overflow), |
200 | * but is only intended to be used with relative (delta) clocksource cycles. |
201 | * |
202 | * XXX - This could use some mult_lxl_ll() asm optimization |
203 | */ |
204 | static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift) |
205 | { |
206 | return ((u64) cycles * mult) >> shift; |
207 | } |
208 | |
209 | |
210 | extern int clocksource_unregister(struct clocksource*); |
211 | extern void clocksource_touch_watchdog(void); |
212 | extern void clocksource_change_rating(struct clocksource *cs, int rating); |
213 | extern void clocksource_suspend(void); |
214 | extern void clocksource_resume(void); |
215 | extern struct clocksource * __init clocksource_default_clock(void); |
216 | extern void clocksource_mark_unstable(struct clocksource *cs); |
217 | extern void |
218 | clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles); |
219 | extern u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 now); |
220 | |
221 | extern u64 |
222 | clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles); |
223 | extern void |
224 | clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); |
225 | |
226 | /* |
227 | * Don't call __clocksource_register_scale directly, use |
228 | * clocksource_register_hz/khz |
229 | */ |
230 | extern int |
231 | __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); |
232 | extern void |
233 | __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq); |
234 | |
235 | /* |
236 | * Don't call this unless you are a default clocksource |
237 | * (AKA: jiffies) and absolutely have to. |
238 | */ |
239 | static inline int __clocksource_register(struct clocksource *cs) |
240 | { |
241 | return __clocksource_register_scale(cs, scale: 1, freq: 0); |
242 | } |
243 | |
244 | static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) |
245 | { |
246 | return __clocksource_register_scale(cs, scale: 1, freq: hz); |
247 | } |
248 | |
249 | static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) |
250 | { |
251 | return __clocksource_register_scale(cs, scale: 1000, freq: khz); |
252 | } |
253 | |
254 | static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz) |
255 | { |
256 | __clocksource_update_freq_scale(cs, scale: 1, freq: hz); |
257 | } |
258 | |
259 | static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz) |
260 | { |
261 | __clocksource_update_freq_scale(cs, scale: 1000, freq: khz); |
262 | } |
263 | |
264 | #ifdef CONFIG_ARCH_CLOCKSOURCE_INIT |
265 | extern void clocksource_arch_init(struct clocksource *cs); |
266 | #else |
267 | static inline void clocksource_arch_init(struct clocksource *cs) { } |
268 | #endif |
269 | |
270 | extern int timekeeping_notify(struct clocksource *clock); |
271 | |
272 | extern u64 clocksource_mmio_readl_up(struct clocksource *); |
273 | extern u64 clocksource_mmio_readl_down(struct clocksource *); |
274 | extern u64 clocksource_mmio_readw_up(struct clocksource *); |
275 | extern u64 clocksource_mmio_readw_down(struct clocksource *); |
276 | |
277 | extern int clocksource_mmio_init(void __iomem *, const char *, |
278 | unsigned long, int, unsigned, u64 (*)(struct clocksource *)); |
279 | |
280 | extern int clocksource_i8253_init(void); |
281 | |
282 | #define TIMER_OF_DECLARE(name, compat, fn) \ |
283 | OF_DECLARE_1_RET(timer, name, compat, fn) |
284 | |
285 | #ifdef CONFIG_TIMER_PROBE |
286 | extern void timer_probe(void); |
287 | #else |
288 | static inline void timer_probe(void) {} |
289 | #endif |
290 | |
291 | #define TIMER_ACPI_DECLARE(name, table_id, fn) \ |
292 | ACPI_DECLARE_PROBE_ENTRY(timer, name, table_id, 0, NULL, 0, fn) |
293 | |
294 | extern ulong max_cswd_read_retries; |
295 | void clocksource_verify_percpu(struct clocksource *cs); |
296 | |
297 | #endif /* _LINUX_CLOCKSOURCE_H */ |
298 | |