f12555d24c
mdelay(1) (i.e. udelay(1000)) does not work correctly due to overflow.
1000 * 0x004189374BC6A7f0 = 0x10000000000000180 (>= 2**64)
0x004189374BC6A7ef (0x004189374BC6A7f0 - 1) is OK and it is exactly
same as catchall case (0x8000000000000000UL / (500000 / HZ)).
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
94 lines
2.4 KiB
C
94 lines
2.4 KiB
C
/*
|
|
* 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) 1994 by Waldorf Electronics
|
|
* Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle
|
|
* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
|
|
*/
|
|
#ifndef _ASM_DELAY_H
|
|
#define _ASM_DELAY_H
|
|
|
|
#include <linux/config.h>
|
|
#include <linux/param.h>
|
|
#include <linux/smp.h>
|
|
#include <asm/compiler.h>
|
|
|
|
static inline void __delay(unsigned long loops)
|
|
{
|
|
if (sizeof(long) == 4)
|
|
__asm__ __volatile__ (
|
|
".set\tnoreorder\n"
|
|
"1:\tbnez\t%0,1b\n\t"
|
|
"subu\t%0,1\n\t"
|
|
".set\treorder"
|
|
: "=r" (loops)
|
|
: "0" (loops));
|
|
else if (sizeof(long) == 8)
|
|
__asm__ __volatile__ (
|
|
".set\tnoreorder\n"
|
|
"1:\tbnez\t%0,1b\n\t"
|
|
"dsubu\t%0,1\n\t"
|
|
".set\treorder"
|
|
:"=r" (loops)
|
|
:"0" (loops));
|
|
}
|
|
|
|
|
|
/*
|
|
* Division by multiplication: you don't have to worry about
|
|
* loss of precision.
|
|
*
|
|
* 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)
|
|
*/
|
|
|
|
static inline void __udelay(unsigned long usecs, unsigned long lpj)
|
|
{
|
|
unsigned long lo;
|
|
|
|
/*
|
|
* The rates of 128 is rounded wrongly by the catchall case
|
|
* for 64-bit. Excessive precission? Probably ...
|
|
*/
|
|
#if defined(CONFIG_64BIT) && (HZ == 128)
|
|
usecs *= 0x0008637bd05af6c7UL; /* 2**64 / (1000000 / HZ) */
|
|
#elif defined(CONFIG_64BIT)
|
|
usecs *= (0x8000000000000000UL / (500000 / HZ));
|
|
#else /* 32-bit junk follows here */
|
|
usecs *= (unsigned long) (((0x8000000000000000ULL / (500000 / HZ)) +
|
|
0x80000000ULL) >> 32);
|
|
#endif
|
|
|
|
if (sizeof(long) == 4)
|
|
__asm__("multu\t%2, %3"
|
|
: "=h" (usecs), "=l" (lo)
|
|
: "r" (usecs), "r" (lpj)
|
|
: GCC_REG_ACCUM);
|
|
else if (sizeof(long) == 8)
|
|
__asm__("dmultu\t%2, %3"
|
|
: "=h" (usecs), "=l" (lo)
|
|
: "r" (usecs), "r" (lpj)
|
|
: GCC_REG_ACCUM);
|
|
|
|
__delay(usecs);
|
|
}
|
|
|
|
#define __udelay_val cpu_data[smp_processor_id()].udelay_val
|
|
|
|
#define udelay(usecs) __udelay((usecs),__udelay_val)
|
|
|
|
/* make sure "usecs *= ..." in udelay do not overflow. */
|
|
#if HZ >= 1000
|
|
#define MAX_UDELAY_MS 1
|
|
#elif HZ <= 200
|
|
#define MAX_UDELAY_MS 5
|
|
#else
|
|
#define MAX_UDELAY_MS (1000 / HZ)
|
|
#endif
|
|
|
|
#endif /* _ASM_DELAY_H */
|