| 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 |