android_kernel_motorola_sm6225/arch/blackfin/include/asm/delay.h
Michael Hennerich 4e653e04cc Blackfin arch: Fix udelay implementation
Avoid possible overflow during 32*32->32 multiplies.

Reported-by: Marco Reppenhagen <marco.reppenhagen@auerswald.de>
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
2009-02-04 16:49:45 +08:00

61 lines
1.2 KiB
C

/*
* delay.h - delay functions
*
* Copyright (c) 2004-2007 Analog Devices Inc.
*
* Licensed under the GPL-2 or later.
*/
#ifndef __ASM_DELAY_H__
#define __ASM_DELAY_H__
#include <mach/anomaly.h>
static inline void __delay(unsigned long loops)
{
if (ANOMALY_05000312) {
/* Interrupted loads to loop registers -> bad */
unsigned long tmp;
__asm__ __volatile__(
"[--SP] = LC0;"
"[--SP] = LT0;"
"[--SP] = LB0;"
"LSETUP (1f,1f) LC0 = %1;"
"1: NOP;"
/* We take advantage of the fact that LC0 is 0 at
* the end of the loop. Otherwise we'd need some
* NOPs after the CLI here.
*/
"CLI %0;"
"LB0 = [SP++];"
"LT0 = [SP++];"
"LC0 = [SP++];"
"STI %0;"
: "=d" (tmp)
: "a" (loops)
);
} else
__asm__ __volatile__ (
"LSETUP(1f, 1f) LC0 = %0;"
"1: NOP;"
:
: "a" (loops)
: "LT0", "LB0", "LC0"
);
}
#include <linux/param.h> /* needed for HZ */
/*
* close approximation borrowed from m68knommu to avoid 64-bit math
*/
#define HZSCALE (268435456 / (1000000/HZ))
static inline void udelay(unsigned long usecs)
{
extern unsigned long loops_per_jiffy;
__delay((((usecs * HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6);
}
#endif