1 | /* SPDX-License-Identifier: GPL-2.0-only */ |
2 | /* |
3 | * sched_clock.h: support for extending counters to full 64-bit ns counter |
4 | */ |
5 | #ifndef LINUX_SCHED_CLOCK |
6 | #define LINUX_SCHED_CLOCK |
7 | |
8 | #include <linux/types.h> |
9 | |
10 | #ifdef CONFIG_GENERIC_SCHED_CLOCK |
11 | /** |
12 | * struct clock_read_data - data required to read from sched_clock() |
13 | * |
14 | * @epoch_ns: sched_clock() value at last update |
15 | * @epoch_cyc: Clock cycle value at last update. |
16 | * @sched_clock_mask: Bitmask for two's complement subtraction of non 64bit |
17 | * clocks. |
18 | * @read_sched_clock: Current clock source (or dummy source when suspended). |
19 | * @mult: Multiplier for scaled math conversion. |
20 | * @shift: Shift value for scaled math conversion. |
21 | * |
22 | * Care must be taken when updating this structure; it is read by |
23 | * some very hot code paths. It occupies <=40 bytes and, when combined |
24 | * with the seqcount used to synchronize access, comfortably fits into |
25 | * a 64 byte cache line. |
26 | */ |
27 | struct clock_read_data { |
28 | u64 epoch_ns; |
29 | u64 epoch_cyc; |
30 | u64 sched_clock_mask; |
31 | u64 (*read_sched_clock)(void); |
32 | u32 mult; |
33 | u32 shift; |
34 | }; |
35 | |
36 | extern struct clock_read_data *sched_clock_read_begin(unsigned int *seq); |
37 | extern int sched_clock_read_retry(unsigned int seq); |
38 | |
39 | extern void generic_sched_clock_init(void); |
40 | |
41 | extern void sched_clock_register(u64 (*read)(void), int bits, |
42 | unsigned long rate); |
43 | #else |
44 | static inline void generic_sched_clock_init(void) { } |
45 | |
46 | static inline void sched_clock_register(u64 (*read)(void), int bits, |
47 | unsigned long rate) |
48 | { |
49 | } |
50 | #endif |
51 | |
52 | #endif |
53 | |