1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0-only */ 2*4882a593Smuzhiyun /* 3*4882a593Smuzhiyun * sched_clock.h: support for extending counters to full 64-bit ns counter 4*4882a593Smuzhiyun */ 5*4882a593Smuzhiyun #ifndef LINUX_SCHED_CLOCK 6*4882a593Smuzhiyun #define LINUX_SCHED_CLOCK 7*4882a593Smuzhiyun 8*4882a593Smuzhiyun #ifdef CONFIG_GENERIC_SCHED_CLOCK 9*4882a593Smuzhiyun /** 10*4882a593Smuzhiyun * struct clock_read_data - data required to read from sched_clock() 11*4882a593Smuzhiyun * 12*4882a593Smuzhiyun * @epoch_ns: sched_clock() value at last update 13*4882a593Smuzhiyun * @epoch_cyc: Clock cycle value at last update. 14*4882a593Smuzhiyun * @sched_clock_mask: Bitmask for two's complement subtraction of non 64bit 15*4882a593Smuzhiyun * clocks. 16*4882a593Smuzhiyun * @read_sched_clock: Current clock source (or dummy source when suspended). 17*4882a593Smuzhiyun * @mult: Multipler for scaled math conversion. 18*4882a593Smuzhiyun * @shift: Shift value for scaled math conversion. 19*4882a593Smuzhiyun * 20*4882a593Smuzhiyun * Care must be taken when updating this structure; it is read by 21*4882a593Smuzhiyun * some very hot code paths. It occupies <=40 bytes and, when combined 22*4882a593Smuzhiyun * with the seqcount used to synchronize access, comfortably fits into 23*4882a593Smuzhiyun * a 64 byte cache line. 24*4882a593Smuzhiyun */ 25*4882a593Smuzhiyun struct clock_read_data { 26*4882a593Smuzhiyun u64 epoch_ns; 27*4882a593Smuzhiyun u64 epoch_cyc; 28*4882a593Smuzhiyun u64 sched_clock_mask; 29*4882a593Smuzhiyun u64 (*read_sched_clock)(void); 30*4882a593Smuzhiyun u32 mult; 31*4882a593Smuzhiyun u32 shift; 32*4882a593Smuzhiyun }; 33*4882a593Smuzhiyun 34*4882a593Smuzhiyun extern struct clock_read_data *sched_clock_read_begin(unsigned int *seq); 35*4882a593Smuzhiyun extern int sched_clock_read_retry(unsigned int seq); 36*4882a593Smuzhiyun 37*4882a593Smuzhiyun extern void generic_sched_clock_init(void); 38*4882a593Smuzhiyun 39*4882a593Smuzhiyun extern void sched_clock_register(u64 (*read)(void), int bits, 40*4882a593Smuzhiyun unsigned long rate); 41*4882a593Smuzhiyun #else generic_sched_clock_init(void)42*4882a593Smuzhiyunstatic inline void generic_sched_clock_init(void) { } 43*4882a593Smuzhiyun sched_clock_register(u64 (* read)(void),int bits,unsigned long rate)44*4882a593Smuzhiyunstatic inline void sched_clock_register(u64 (*read)(void), int bits, 45*4882a593Smuzhiyun unsigned long rate) 46*4882a593Smuzhiyun { 47*4882a593Smuzhiyun } 48*4882a593Smuzhiyun #endif 49*4882a593Smuzhiyun 50*4882a593Smuzhiyun #endif 51