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