49 lines
1.1 KiB
C
49 lines
1.1 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Precise Delay Loops for S390
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*
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* Copyright IBM Corp. 1999, 2008
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* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
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*/
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#include <linux/processor.h>
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#include <linux/delay.h>
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#include <asm/div64.h>
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#include <asm/timex.h>
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void __delay(unsigned long loops)
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{
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/*
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* To end the bloody studid and useless discussion about the
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* BogoMips number I took the liberty to define the __delay
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* function in a way that that resulting BogoMips number will
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* yield the megahertz number of the cpu. The important function
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* is udelay and that is done using the tod clock. -- martin.
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*/
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asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
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}
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EXPORT_SYMBOL(__delay);
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static void delay_loop(unsigned long delta)
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{
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unsigned long end;
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end = get_tod_clock_monotonic() + delta;
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while (!tod_after(get_tod_clock_monotonic(), end))
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cpu_relax();
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}
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void __udelay(unsigned long usecs)
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{
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delay_loop(usecs << 12);
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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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nsecs <<= 9;
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do_div(nsecs, 125);
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delay_loop(nsecs);
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}
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EXPORT_SYMBOL(__ndelay);
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