57 lines
1.3 KiB
C
57 lines
1.3 KiB
C
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/*
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* Precise Delay Loops for Meta
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*
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* Copyright (C) 1993 Linus Torvalds
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* Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
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* Copyright (C) 2007,2009 Imagination Technologies Ltd.
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*
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*/
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#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/delay.h>
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#include <asm/core_reg.h>
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#include <asm/processor.h>
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/*
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* TXTACTCYC is only 24 bits, so on chips with fast clocks it will wrap
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* many times per-second. If it does wrap __delay will return prematurely,
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* but this is only likely with large delay values.
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*
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* We also can't implement read_current_timer() with TXTACTCYC due to
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* this wrapping behaviour.
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*/
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#define rdtimer(t) t = __core_reg_get(TXTACTCYC)
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void __delay(unsigned long loops)
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{
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unsigned long bclock, now;
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rdtimer(bclock);
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do {
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asm("NOP");
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rdtimer(now);
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} while ((now-bclock) < loops);
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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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u64 loops = (u64)xloops * (u64)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 * 0x000010c7); /* 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 * 0x00005); /* 2**32 / 1000000000 (rounded up) */
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}
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EXPORT_SYMBOL(__ndelay);
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