1/*
2 * Copyright (c) 2000-2007 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 * Mach Operating System
33 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
34 * All Rights Reserved.
35 *
36 * Permission to use, copy, modify and distribute this software and its
37 * documentation is hereby granted, provided that both the copyright
38 * notice and this permission notice appear in all copies of the
39 * software, derivative works or modified versions, and any portions
40 * thereof, and that both notices appear in supporting documentation.
41 *
42 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
43 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
44 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
45 *
46 * Carnegie Mellon requests users of this software to return to
47 *
48 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
49 *  School of Computer Science
50 *  Carnegie Mellon University
51 *  Pittsburgh PA 15213-3890
52 *
53 * any improvements or extensions that they make and grant Carnegie Mellon
54 * the rights to redistribute these changes.
55 */
56/*
57 */
58
59#ifndef	_KERN_TIMER_H_
60#define _KERN_TIMER_H_
61
62#include <kern/kern_types.h>
63
64/*
65 * Some platforms have very expensive timebase routines. An optimization
66 * is to avoid switching timers on kernel exit/entry, which results in all
67 * time billed to the system timer. However, when exposed to userspace,
68 * we report as user time to indicate that work was done on behalf of
69 * userspace.
70 *
71 * Although this policy is implemented as a global variable, we snapshot it
72 * at key points in the thread structure (when the thread is locked and
73 * executing in the kernel) to avoid imbalances.
74 */
75extern int precise_user_kernel_time;
76
77/*
78 * thread must be locked, or be the current executing thread, so that
79 * it doesn't transition from user to kernel while updating the
80 * thread-local value (or in kernel debugger context). In the future,
81 * we make take into account task-level or thread-level policy.
82 */
83#define use_precise_user_kernel_time(thread) ( precise_user_kernel_time )
84
85/*
86 *	Definitions for high resolution timers.  A check
87 *	word on the high portion allows atomic updates.
88 */
89
90struct timer {
91	uint64_t	tstamp;
92#if	defined(__LP64__)
93	uint64_t	all_bits;
94#else
95	uint32_t	low_bits;
96	uint32_t	high_bits;
97	uint32_t	high_bits_check;
98#endif
99};
100
101typedef struct timer	timer_data_t, *timer_t;
102
103/*
104 *	Exported kernel interface to timers
105 */
106
107/* Start a timer by setting the timestamp */
108extern void		timer_start(
109					timer_t		timer,
110					uint64_t	tstamp);
111
112/* Stop a timer by updating from the timestamp */
113extern void		timer_stop(
114					timer_t		timer,
115					uint64_t	tstamp);
116
117/* Update the timer and start a new one */
118extern void		timer_switch(
119					timer_t		timer,
120					uint64_t	tstamp,
121					timer_t		new_timer);
122
123/* Update the thread timer at an event */
124extern void		thread_timer_event(
125					uint64_t	tstamp,
126					timer_t		new_timer);
127
128/* Initialize a timer */
129extern void		timer_init(
130					timer_t		timer);
131
132/* Update a saved timer value and return delta to current value */
133extern uint64_t	timer_delta(
134					timer_t		timer,
135					uint64_t	*save);
136
137/* Advance a timer by a 64 bit value */
138extern void		timer_advance(
139					timer_t		timer,
140					uint64_t	delta);
141
142/*
143 *	Exported hardware interface to timers
144 */
145
146/* Read timer value */
147#if	defined(__LP64__)
148static inline uint64_t timer_grab(
149					timer_t		timer)
150{
151	return timer->all_bits;
152}
153#else
154extern uint64_t	timer_grab(
155					timer_t		timer);
156
157/* Update timer value */
158extern void		timer_update(
159					timer_t		timer,
160					uint32_t	new_high,
161					uint32_t	new_low);
162#endif	/* defined(__LP64__) */
163
164#endif	/* _KERN_TIMER_H_ */
165