xref: /openbmc/linux/arch/x86/include/asm/pvclock.h (revision b595076a)
1 #ifndef _ASM_X86_PVCLOCK_H
2 #define _ASM_X86_PVCLOCK_H
3 
4 #include <linux/clocksource.h>
5 #include <asm/pvclock-abi.h>
6 
7 /* some helper functions for xen and kvm pv clock sources */
8 cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
9 void pvclock_set_flags(u8 flags);
10 unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
11 void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
12 			    struct pvclock_vcpu_time_info *vcpu,
13 			    struct timespec *ts);
14 
15 /*
16  * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
17  * yielding a 64-bit result.
18  */
19 static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
20 {
21 	u64 product;
22 #ifdef __i386__
23 	u32 tmp1, tmp2;
24 #endif
25 
26 	if (shift < 0)
27 		delta >>= -shift;
28 	else
29 		delta <<= shift;
30 
31 #ifdef __i386__
32 	__asm__ (
33 		"mul  %5       ; "
34 		"mov  %4,%%eax ; "
35 		"mov  %%edx,%4 ; "
36 		"mul  %5       ; "
37 		"xor  %5,%5    ; "
38 		"add  %4,%%eax ; "
39 		"adc  %5,%%edx ; "
40 		: "=A" (product), "=r" (tmp1), "=r" (tmp2)
41 		: "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
42 #elif defined(__x86_64__)
43 	__asm__ (
44 		"mul %%rdx ; shrd $32,%%rdx,%%rax"
45 		: "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );
46 #else
47 #error implement me!
48 #endif
49 
50 	return product;
51 }
52 
53 #endif /* _ASM_X86_PVCLOCK_H */
54