56 lines
1.1 KiB
C
56 lines
1.1 KiB
C
/*
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* Copyright (C) 1993, 2000 Linus Torvalds
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*
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* Delay routines, using a pre-computed "loops_per_jiffy" value.
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*/
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#include <linux/module.h>
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#include <linux/sched.h> /* for udelay's use of smp_processor_id */
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#include <asm/param.h>
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#include <asm/smp.h>
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#include <linux/delay.h>
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/*
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* Use only for very small delays (< 1 msec).
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*
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* The active part of our cycle counter is only 32-bits wide, and
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* we're treating the difference between two marks as signed. On
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* a 1GHz box, that's about 2 seconds.
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*/
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void
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__delay(int loops)
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{
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int tmp;
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__asm__ __volatile__(
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" rpcc %0\n"
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" addl %1,%0,%1\n"
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"1: rpcc %0\n"
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" subl %1,%0,%0\n"
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" bgt %0,1b"
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: "=&r" (tmp), "=r" (loops) : "1"(loops));
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}
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EXPORT_SYMBOL(__delay);
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#ifdef CONFIG_SMP
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#define LPJ cpu_data[smp_processor_id()].loops_per_jiffy
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#else
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#define LPJ loops_per_jiffy
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#endif
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void
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udelay(unsigned long usecs)
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{
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usecs *= (((unsigned long)HZ << 32) / 1000000) * LPJ;
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__delay((long)usecs >> 32);
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}
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EXPORT_SYMBOL(udelay);
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void
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ndelay(unsigned long nsecs)
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{
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nsecs *= (((unsigned long)HZ << 32) / 1000000000) * LPJ;
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__delay((long)nsecs >> 32);
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}
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EXPORT_SYMBOL(ndelay);
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