Current File : //usr/src/linux-headers-5.15.0-43/arch/m68k/include/asm/delay.h
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _M68K_DELAY_H
#define _M68K_DELAY_H
#include <asm/param.h>
/*
* Copyright (C) 1994 Hamish Macdonald
* Copyright (C) 2004 Greg Ungerer <gerg@uclinux.com>
*
* Delay routines, using a pre-computed "loops_per_jiffy" value.
*/
#if defined(CONFIG_COLDFIRE)
/*
* The ColdFire runs the delay loop at significantly different speeds
* depending upon long word alignment or not. We'll pad it to
* long word alignment which is the faster version.
* The 0x4a8e is of course a 'tstl %fp' instruction. This is better
* than using a NOP (0x4e71) instruction because it executes in one
* cycle not three and doesn't allow for an arbitrary delay waiting
* for bus cycles to finish. Also fp/a6 isn't likely to cause a
* stall waiting for the register to become valid if such is added
* to the coldfire at some stage.
*/
#define DELAY_ALIGN ".balignw 4, 0x4a8e\n\t"
#else
/*
* No instruction alignment required for other m68k types.
*/
#define DELAY_ALIGN
#endif
static inline void __delay(unsigned long loops)
{
__asm__ __volatile__ (
DELAY_ALIGN
"1: subql #1,%0\n\t"
"jcc 1b"
: "=d" (loops)
: "0" (loops));
}
extern void __bad_udelay(void);
#ifdef CONFIG_CPU_HAS_NO_MULDIV64
/*
* The simpler m68k and ColdFire processors do not have a 32*32->64
* multiply instruction. So we need to handle them a little differently.
* We use a bit of shifting and a single 32*32->32 multiply to get close.
*/
#define HZSCALE (268435456 / (1000000 / HZ))
#define __const_udelay(u) \
__delay(((((u) * HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6)
#else
static inline void __xdelay(unsigned long xloops)
{
unsigned long tmp;
__asm__ ("mulul %2,%0:%1"
: "=d" (xloops), "=d" (tmp)
: "d" (xloops), "1" (loops_per_jiffy));
__delay(xloops * HZ);
}
/*
* The definition of __const_udelay is specifically made a macro so that
* the const factor (4295 = 2**32 / 1000000) can be optimized out when
* the delay is a const.
*/
#define __const_udelay(n) (__xdelay((n) * 4295))
#endif
static inline void __udelay(unsigned long usecs)
{
__const_udelay(usecs);
}
/*
* Use only for very small delays ( < 1 msec). Should probably use a
* lookup table, really, as the multiplications take much too long with
* short delays. This is a "reasonable" implementation, though (and the
* first constant multiplications gets optimized away if the delay is
* a constant)
*/
#define udelay(n) (__builtin_constant_p(n) ? \
((n) > 20000 ? __bad_udelay() : __const_udelay(n)) : __udelay(n))
/*
* nanosecond delay:
*
* ((((HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6) is the number of loops
* per microsecond
*
* 1000 / ((((HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6) is the number of
* nanoseconds per loop
*
* So n / ( 1000 / ((((HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6) ) would
* be the number of loops for n nanoseconds
*/
/*
* The simpler m68k and ColdFire processors do not have a 32*32->64
* multiply instruction. So we need to handle them a little differently.
* We use a bit of shifting and a single 32*32->32 multiply to get close.
* This is a macro so that the const version can factor out the first
* multiply and shift.
*/
#define HZSCALE (268435456 / (1000000 / HZ))
static inline void ndelay(unsigned long nsec)
{
__delay(DIV_ROUND_UP(nsec *
((((HZSCALE) >> 11) *
(loops_per_jiffy >> 11)) >> 6),
1000));
}
#define ndelay(n) ndelay(n)
#endif /* defined(_M68K_DELAY_H) */
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