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 
20 extern void __delay(unsigned long loops);
21 extern 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 */
73