1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_X86_TIMER_H 3 #define _ASM_X86_TIMER_H 4 #include <linux/pm.h> 5 #include <linux/percpu.h> 6 #include <linux/interrupt.h> 7 #include <linux/math64.h> 8 9 unsigned long long native_sched_clock(void); 10 extern void recalibrate_cpu_khz(void); 11 12 extern int no_timer_check; 13 14 extern bool using_native_sched_clock(void); 15 void paravirt_set_sched_clock(u64 (*func)(void)); 16 17 /* 18 * We use the full linear equation: f(x) = a + b*x, in order to allow 19 * a continuous function in the face of dynamic freq changes. 20 * 21 * Continuity means that when our frequency changes our slope (b); we want to 22 * ensure that: f(t) == f'(t), which gives: a + b*t == a' + b'*t. 23 * 24 * Without an offset (a) the above would not be possible. 25 * 26 * See the comment near cycles_2_ns() for details on how we compute (b). 27 */ 28 struct cyc2ns_data { 29 u32 cyc2ns_mul; 30 u32 cyc2ns_shift; 31 u64 cyc2ns_offset; 32 }; /* 16 bytes */ 33 34 extern void cyc2ns_read_begin(struct cyc2ns_data *); 35 extern void cyc2ns_read_end(void); 36 37 #endif /* _ASM_X86_TIMER_H */ 38