77 lines
3.2 KiB
C
77 lines
3.2 KiB
C
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef _ASM_POWERPC_DELAY_H
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#define _ASM_POWERPC_DELAY_H
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#ifdef __KERNEL__
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#include <linux/processor.h>
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#include <asm/time.h>
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/*
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* Copyright 1996, Paul Mackerras.
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* Copyright (C) 2009 Freescale Semiconductor, Inc. All rights reserved.
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*
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* PPC64 Support added by Dave Engebretsen, Todd Inglett, Mike Corrigan,
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* Anton Blanchard.
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*/
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extern void __delay(unsigned long loops);
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extern void udelay(unsigned long usecs);
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/*
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* On shared processor machines the generic implementation of mdelay can
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* result in large errors. While each iteration of the loop inside mdelay
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* is supposed to take 1ms, the hypervisor could sleep our partition for
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* longer (eg 10ms). With the right timing these errors can add up.
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*
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* Since there is no 32bit overflow issue on 64bit kernels, just call
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* udelay directly.
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*/
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#ifdef CONFIG_PPC64
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#define mdelay(n) udelay((n) * 1000)
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#endif
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/**
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* spin_event_timeout - spin until a condition gets true or a timeout elapses
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* @condition: a C expression to evalate
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* @timeout: timeout, in microseconds
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* @delay: the number of microseconds to delay between each evaluation of
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* @condition
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*
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* The process spins until the condition evaluates to true (non-zero) or the
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* timeout elapses. The return value of this macro is the value of
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* @condition when the loop terminates. This allows you to determine the cause
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* of the loop terminates. If the return value is zero, then you know a
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* timeout has occurred.
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*
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* This primary purpose of this macro is to poll on a hardware register
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* until a status bit changes. The timeout ensures that the loop still
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* terminates even if the bit never changes. The delay is for devices that
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* need a delay in between successive reads.
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*
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* gcc will optimize out the if-statement if @delay is a constant.
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*/
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#define spin_event_timeout(condition, timeout, delay) \
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({ \
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typeof(condition) __ret; \
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unsigned long __loops = tb_ticks_per_usec * timeout; \
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unsigned long __start = mftb(); \
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\
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if (delay) { \
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while (!(__ret = (condition)) && \
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(tb_ticks_since(__start) <= __loops)) \
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udelay(delay); \
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} else { \
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spin_begin(); \
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while (!(__ret = (condition)) && \
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(tb_ticks_since(__start) <= __loops)) \
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spin_cpu_relax(); \
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spin_end(); \
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} \
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if (!__ret) \
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__ret = (condition); \
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__ret; \
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})
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#endif /* __KERNEL__ */
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#endif /* _ASM_POWERPC_DELAY_H */
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