73 lines
2 KiB
C
73 lines
2 KiB
C
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/*
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* include/asm-microblaze/delay.h
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2008 Michal Simek
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* Copyright (C) 2007 John Williams
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* Copyright (C) 2006 Atmark Techno, Inc.
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*/
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#ifndef _ASM_MICROBLAZE_DELAY_H
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#define _ASM_MICROBLAZE_DELAY_H
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extern inline void __delay(unsigned long loops)
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{
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asm volatile ("# __delay \n\t" \
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"1: addi %0, %0, -1\t\n" \
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"bneid %0, 1b \t\n" \
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"nop \t\n"
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: "=r" (loops)
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: "0" (loops));
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}
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/*
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* Note that 19 * 226 == 4294 ==~ 2^32 / 10^6, so
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* loops = (4294 * usecs * loops_per_jiffy * HZ) / 2^32.
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*
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* The mul instruction gives us loops = (a * b) / 2^32.
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* We choose a = usecs * 19 * HZ and b = loops_per_jiffy * 226
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* because this lets us support a wide range of HZ and
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* loops_per_jiffy values without either a or b overflowing 2^32.
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* Thus we need usecs * HZ <= (2^32 - 1) / 19 = 226050910 and
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* loops_per_jiffy <= (2^32 - 1) / 226 = 19004280
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* (which corresponds to ~3800 bogomips at HZ = 100).
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* -- paulus
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*/
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#define __MAX_UDELAY (226050910UL/HZ) /* maximum udelay argument */
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#define __MAX_NDELAY (4294967295UL/HZ) /* maximum ndelay argument */
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extern unsigned long loops_per_jiffy;
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extern inline void __udelay(unsigned int x)
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{
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unsigned long long tmp =
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(unsigned long long)x * (unsigned long long)loops_per_jiffy \
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* 226LL;
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unsigned loops = tmp >> 32;
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/*
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__asm__("mulxuu %0,%1,%2" : "=r" (loops) :
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"r" (x), "r" (loops_per_jiffy * 226));
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*/
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__delay(loops);
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}
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extern void __bad_udelay(void); /* deliberately undefined */
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extern void __bad_ndelay(void); /* deliberately undefined */
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#define udelay(n) (__builtin_constant_p(n) ? \
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((n) > __MAX_UDELAY ? __bad_udelay() : __udelay((n) * (19 * HZ))) : \
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__udelay((n) * (19 * HZ)))
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#define ndelay(n) (__builtin_constant_p(n) ? \
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((n) > __MAX_NDELAY ? __bad_ndelay() : __udelay((n) * HZ)) : \
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__udelay((n) * HZ))
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#define muldiv(a, b, c) (((a)*(b))/(c))
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#endif /* _ASM_MICROBLAZE_DELAY_H */
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