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/arch/powerpc/include/asm/delay.h

https://github.com/aicjofs/android_kernel_lge_v500_20d
C Header | 72 lines | 25 code | 6 blank | 41 comment | 5 complexity | 57f037ce2dbfaeb5613af711e6c89a86 MD5 | raw file
 1#ifndef _ASM_POWERPC_DELAY_H
 2#define _ASM_POWERPC_DELAY_H
 3#ifdef __KERNEL__
 4
 5#include <asm/time.h>
 6
 7/*
 8 * Copyright 1996, Paul Mackerras.
 9 * Copyright (C) 2009 Freescale Semiconductor, Inc. All rights reserved.
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
15 *
16 * PPC64 Support added by Dave Engebretsen, Todd Inglett, Mike Corrigan,
17 * Anton Blanchard.
18 */
19
20extern void __delay(unsigned long loops);
21extern void udelay(unsigned long usecs);
22
23/*
24 * On shared processor machines the generic implementation of mdelay can
25 * result in large errors. While each iteration of the loop inside mdelay
26 * is supposed to take 1ms, the hypervisor could sleep our partition for
27 * longer (eg 10ms). With the right timing these errors can add up.
28 *
29 * Since there is no 32bit overflow issue on 64bit kernels, just call
30 * udelay directly.
31 */
32#ifdef CONFIG_PPC64
33#define mdelay(n)	udelay((n) * 1000)
34#endif
35
36/**
37 * spin_event_timeout - spin until a condition gets true or a timeout elapses
38 * @condition: a C expression to evalate
39 * @timeout: timeout, in microseconds
40 * @delay: the number of microseconds to delay between each evaluation of
41 *         @condition
42 *
43 * The process spins until the condition evaluates to true (non-zero) or the
44 * timeout elapses.  The return value of this macro is the value of
45 * @condition when the loop terminates. This allows you to determine the cause
46 * of the loop terminates.  If the return value is zero, then you know a
47 * timeout has occurred.
48 *
49 * This primary purpose of this macro is to poll on a hardware register
50 * until a status bit changes.  The timeout ensures that the loop still
51 * terminates even if the bit never changes.  The delay is for devices that
52 * need a delay in between successive reads.
53 *
54 * gcc will optimize out the if-statement if @delay is a constant.
55 */
56#define spin_event_timeout(condition, timeout, delay)                          \
57({                                                                             \
58	typeof(condition) __ret;                                               \
59	unsigned long __loops = tb_ticks_per_usec * timeout;                   \
60	unsigned long __start = get_tbl();                                     \
61	while (!(__ret = (condition)) && (tb_ticks_since(__start) <= __loops)) \
62		if (delay)                                                     \
63			udelay(delay);                                         \
64		else                                                           \
65			cpu_relax();                                           \
66	if (!__ret)                                                            \
67		__ret = (condition);                                           \
68	__ret;		                                                       \
69})
70
71#endif /* __KERNEL__ */
72#endif /* _ASM_POWERPC_DELAY_H */