1/*
2 * Copyright (c) 2004-2007 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28/*
29 * @OSF_COPYRIGHT@
30 */
31/*
32 * @APPLE_FREE_COPYRIGHT@
33 */
34/*
35 *	File:		rtclock.h
36 *	Purpose:	Routines for handling the machine dependent
37 *				real-time clock.
38 */
39
40#ifndef _I386_RTCLOCK_H_
41#define _I386_RTCLOCK_H_
42
43#ifndef ASSEMBLER
44typedef struct rtc_nanotime {
45	uint64_t	tsc_base;		/* timestamp */
46	uint64_t	ns_base;		/* nanoseconds */
47	uint32_t	scale;			/* tsc -> nanosec multiplier */
48	uint32_t	shift;			/* tsc -> nanosec shift/div */
49						/* shift is overloaded with
50						 * lower 32bits of tsc_freq
51						 * on slower machines (SLOW_TSC_THRESHOLD) */
52	uint32_t	generation;		/* 0 == being updated */
53	uint32_t	spare1;
54} rtc_nanotime_t;
55
56#include <kern/etimer.h>
57
58struct cpu_data;
59
60extern void	_rtc_nanotime_store(
61			uint64_t	tsc,
62			uint64_t	nsec,
63			uint32_t	scale,
64			uint32_t	shift,
65			rtc_nanotime_t	*dst);
66
67extern uint64_t	_rtc_nanotime_read(
68			rtc_nanotime_t	*rntp,
69			int		slow);
70
71extern rtc_nanotime_t	rtc_nanotime_info;
72#endif
73
74#define	SLOW_TSC_THRESHOLD	1000067800	/* TSC is too slow for regular nanotime() algorithm */
75
76#if defined(__i386__)
77/*
78 * Assembly snippet included in exception handlers and rtc_nanotime_read()
79 * %edi points to nanotime info struct
80 * %edx:%eax returns nanotime
81 */
82#define RTC_NANOTIME_READ_FAST()					  \
830:	movl	RNT_GENERATION(%edi),%esi	/* being updated? */	; \
84	testl	%esi,%esi						; \
85	jz	0b				/* wait until done */	; \
86	lfence								; \
87	rdtsc								; \
88	lfence								; \
89	subl	RNT_TSC_BASE(%edi),%eax					; \
90	sbbl	RNT_TSC_BASE+4(%edi),%edx	/* tsc - tsc_base */	; \
91	movl	RNT_SCALE(%edi),%ecx		/* * scale factor */	; \
92	movl	%edx,%ebx						; \
93	mull	%ecx							; \
94	movl	%ebx,%eax						; \
95	movl	%edx,%ebx						; \
96	mull	%ecx							; \
97	addl	%ebx,%eax						; \
98	adcl	$0,%edx							; \
99	addl	RNT_NS_BASE(%edi),%eax		/* + ns_base */		; \
100	adcl	RNT_NS_BASE+4(%edi),%edx				; \
101	cmpl	RNT_GENERATION(%edi),%esi	/* check for update */	; \
102	jne	0b				/* do it all again */
103
104#elif defined(__x86_64__)
105
106/*
107 * Assembly snippet included in exception handlers and rtc_nanotime_read()
108 * %rdi points to nanotime info struct.
109 * %rax returns nanotime
110 */
111#define RTC_NANOTIME_READ_FAST()					  \
1120:	movl	RNT_GENERATION(%rdi),%esi				; \
113	test	%esi,%esi			/* info updating? */	; \
114	jz	0b				/* - wait if so */	; \
115	lfence								; \
116	rdtsc								; \
117	lfence								; \
118	shlq	$32,%rdx						; \
119	orq	%rdx,%rax			/* %rax := tsc */	; \
120	subq	RNT_TSC_BASE(%rdi),%rax		/* tsc - tsc_base */	; \
121	xorq	%rcx,%rcx						; \
122	movl	RNT_SCALE(%rdi),%ecx					; \
123	mulq	%rcx				/* delta * scale */	; \
124	shrdq	$32,%rdx,%rax			/* %rdx:%rax >>= 32 */	; \
125	addq	RNT_NS_BASE(%rdi),%rax		/* add ns_base */	; \
126	cmpl	RNT_GENERATION(%rdi),%esi	/* repeat if changed */ ; \
127	jne	0b
128
129#endif
130
131#endif /* _I386_RTCLOCK_H_ */
132