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
17 extern void __delay(unsigned long loops);
18 extern 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 */
77
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.