forked from Minki/linux
807607f79b
If the counter overflows during a __delay operation, we will exit the loop prematurely. For example, calling __delay(0x100) with the counter at 0xffffff00 gives us a target of 0x0. The unsigned comparison in the while loop will likely be false on the first iteration (if the counter is now anything other than 0) and we will return early. This patch fixes the problem by comparing deltas in the loop rather than absolute values. Cc: Jon Masters <jcm@redhat.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Jonas Bonn <jonas@southpole.se>
61 lines
1.4 KiB
C
61 lines
1.4 KiB
C
/*
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* OpenRISC Linux
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*
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* Linux architectural port borrowing liberally from similar works of
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* others. All original copyrights apply as per the original source
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* declaration.
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*
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* Modifications for the OpenRISC architecture:
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* Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation
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*
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* Precise Delay Loops
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <asm/delay.h>
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#include <asm/timex.h>
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#include <asm/processor.h>
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int __devinit read_current_timer(unsigned long *timer_value)
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{
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*timer_value = mfspr(SPR_TTCR);
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return 0;
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}
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void __delay(unsigned long cycles)
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{
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cycles_t start = get_cycles();
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while ((get_cycles() - start) < cycles)
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cpu_relax();
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}
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EXPORT_SYMBOL(__delay);
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inline void __const_udelay(unsigned long xloops)
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{
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unsigned long long loops;
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loops = (unsigned long long)xloops * loops_per_jiffy * HZ;
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__delay(loops >> 32);
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}
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EXPORT_SYMBOL(__const_udelay);
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void __udelay(unsigned long usecs)
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{
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__const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
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}
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EXPORT_SYMBOL(__udelay);
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void __ndelay(unsigned long nsecs)
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{
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__const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
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}
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EXPORT_SYMBOL(__ndelay);
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