1/* SPDX-License-Identifier: GPL-2.0-or-later */
 2#ifndef _ASM_POWERPC_DELAY_H
 3#define _ASM_POWERPC_DELAY_H
 4#ifdef __KERNEL__
 5
 6#include <linux/processor.h>
 7#include <asm/time.h>
 8
 9/*
10 * Copyright 1996, Paul Mackerras.
11 * Copyright (C) 2009 Freescale Semiconductor, Inc. All rights reserved.
12 *
13 * PPC64 Support added by Dave Engebretsen, Todd Inglett, Mike Corrigan,
14 * Anton Blanchard.
15 */
16
17extern void __delay(unsigned long loops);
18extern void udelay(unsigned long usecs);
19
20/*
21 * On shared processor machines the generic implementation of mdelay can
22 * result in large errors. While each iteration of the loop inside mdelay
23 * is supposed to take 1ms, the hypervisor could sleep our partition for
24 * longer (eg 10ms). With the right timing these errors can add up.
25 *
26 * Since there is no 32bit overflow issue on 64bit kernels, just call
27 * udelay directly.
28 */
29#ifdef CONFIG_PPC64
30#define mdelay(n)	udelay((n) * 1000)
31#endif
32
33/**
34 * spin_event_timeout - spin until a condition gets true or a timeout elapses
35 * @condition: a C expression to evalate
36 * @timeout: timeout, in microseconds
37 * @delay: the number of microseconds to delay between each evaluation of
38 *         @condition
39 *
40 * The process spins until the condition evaluates to true (non-zero) or the
41 * timeout elapses.  The return value of this macro is the value of
42 * @condition when the loop terminates. This allows you to determine the cause
43 * of the loop terminates.  If the return value is zero, then you know a
44 * timeout has occurred.
45 *
46 * This primary purpose of this macro is to poll on a hardware register
47 * until a status bit changes.  The timeout ensures that the loop still
48 * terminates even if the bit never changes.  The delay is for devices that
49 * need a delay in between successive reads.
50 *
51 * gcc will optimize out the if-statement if @delay is a constant.
52 */
53#define spin_event_timeout(condition, timeout, delay)                          \
54({                                                                             \
55	typeof(condition) __ret;                                               \
56	unsigned long __loops = tb_ticks_per_usec * timeout;                   \
57	unsigned long __start = mftb();                                     \
58                                                                               \
59	if (delay) {                                                           \
60		while (!(__ret = (condition)) &&                               \
61				(tb_ticks_since(__start) <= __loops))          \
62			udelay(delay);                                         \
63	} else {                                                               \
64		spin_begin();                                                  \
65		while (!(__ret = (condition)) &&                               \
66				(tb_ticks_since(__start) <= __loops))          \
67			spin_cpu_relax();                                      \
68		spin_end();                                                    \
69	}                                                                      \
70	if (!__ret)                                                            \
71		__ret = (condition);                                           \
72	__ret;		                                                       \
73})
74
75#endif /* __KERNEL__ */
76#endif /* _ASM_POWERPC_DELAY_H */