mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-28 07:04:00 +08:00
01e3b3cb2d
Avoid __delay counter underflow for loop counts < 2. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Chris Zankel <chris@zankel.net>
45 lines
1.1 KiB
C
45 lines
1.1 KiB
C
/*
|
|
* include/asm-xtensa/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) 2001 - 2005 Tensilica Inc.
|
|
*
|
|
*/
|
|
|
|
#ifndef _XTENSA_DELAY_H
|
|
#define _XTENSA_DELAY_H
|
|
|
|
#include <asm/timex.h>
|
|
#include <asm/param.h>
|
|
|
|
extern unsigned long loops_per_jiffy;
|
|
|
|
static inline void __delay(unsigned long loops)
|
|
{
|
|
if (__builtin_constant_p(loops) && loops < 2)
|
|
__asm__ __volatile__ ("nop");
|
|
else if (loops >= 2)
|
|
/* 2 cycles per loop. */
|
|
__asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b"
|
|
: "+r" (loops));
|
|
}
|
|
|
|
/* For SMP/NUMA systems, change boot_cpu_data to something like
|
|
* local_cpu_data->... where local_cpu_data points to the current
|
|
* cpu. */
|
|
|
|
static __inline__ void udelay (unsigned long usecs)
|
|
{
|
|
unsigned long start = get_ccount();
|
|
unsigned long cycles = usecs * (loops_per_jiffy / (1000000UL / HZ));
|
|
|
|
/* Note: all variables are unsigned (can wrap around)! */
|
|
while (((unsigned long)get_ccount()) - start < cycles)
|
|
;
|
|
}
|
|
|
|
#endif
|