mailboxbomb/loader/time.c
2015-09-02 23:13:18 -04:00

32 lines
615 B
C

// Copyright 2008-2009 Segher Boessenkool <segher@kernel.crashing.org>
// This code is licensed to you under the terms of the GNU GPL, version 2;
// see file COPYING or http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
#include "loader.h"
// Timebase frequency is bus frequency / 4. Ignore roundoff, this
// doesn't have to be very accurate.
#define TICKS_PER_USEC (243/4)
static u32 mftb(void)
{
u32 x;
asm volatile("mftb %0" : "=r"(x));
return x;
}
static void __delay(u32 ticks)
{
u32 start = mftb();
while (mftb() - start < ticks)
;
}
void udelay(u32 us)
{
__delay(TICKS_PER_USEC * us);
}