1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _TIMEKEEPING_INTERNAL_H
3 #define _TIMEKEEPING_INTERNAL_H
4 /*
5  * timekeeping debug functions
6  */
7 #include <linux/clocksource.h>
8 #include <linux/time.h>
9 
10 #ifdef CONFIG_DEBUG_FS
11 extern void tk_debug_account_sleep_time(const struct timespec64 *t);
12 #else
13 #define tk_debug_account_sleep_time(x)
14 #endif
15 
16 #ifdef CONFIG_CLOCKSOURCE_VALIDATE_LAST_CYCLE
17 static inline u64 clocksource_delta(u64 now, u64 last, u64 mask)
18 {
19 	u64 ret = (now - last) & mask;
20 
21 	/*
22 	 * Prevent time going backwards by checking the MSB of mask in
23 	 * the result. If set, return 0.
24 	 */
25 	return ret & ~(mask >> 1) ? 0 : ret;
26 }
27 #else
28 static inline u64 clocksource_delta(u64 now, u64 last, u64 mask)
29 {
30 	return (now - last) & mask;
31 }
32 #endif
33 
34 #endif /* _TIMEKEEPING_INTERNAL_H */
35