u-boot/board/edb93xx/early_udelay.h

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/*
* Copyright (C) 2009 Matthias Kaehlcke <matthias@kaehlcke.net>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <common.h>
/* delay execution before timers are initialized */
static inline void early_udelay(uint32_t usecs)
{
/* loop takes 4 cycles at 5.0ns (fastest case, running at 200MHz) */
register uint32_t loops = usecs * (1000 / 20);
__asm__ volatile ("1:\n"
"subs %0, %1, #1\n"
"bne 1b":"=r" (loops):"0" (loops));
}