/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Copied from <file:arch/powerpc/kernel/misc_32.S>
*
* This file contains miscellaneous low-level functions.
* Copyright (C) 1995-1996 Gary Thomas ([email protected])
*
* Largely rewritten by Cort Dougan ([email protected])
* and Paul Mackerras.
*
* kexec bits:
* Copyright (C) 2002-2003 Eric Biederman <[email protected]>
* GameCube/ppc32 port Copyright (C) 2004 Albert Herranz
*/
#include "ppc_asm.h"
#define SPRN_PVR 0x11F /* Processor Version Register */
.text
/* udelay needs to know the period of the
* timebase in nanoseconds. This used to be hardcoded to be 60ns
* (period of 66MHz/4). Now a variable is used that is initialized to
* 60 for backward compatibility, but it can be overridden as necessary
* with code something like this:
* extern unsigned long timebase_period_ns;
* timebase_period_ns = 1000000000 / bd->bi_tbfreq;
*/
.data
.globl timebase_period_ns
timebase_period_ns:
.long 60
.text
/*
* Delay for a number of microseconds
*/
.globl udelay
udelay:
mulli r4,r3,1000 /* nanoseconds */
/* Change r4 to be the number of ticks using:
* (nanoseconds + (timebase_period_ns - 1 )) / timebase_period_ns
* timebase_period_ns defaults to 60 (16.6MHz) */
mflr r5
bcl 20,31,0f
0: mflr r6
mtlr r5
addis r5,r6,(timebase_period_ns-0b)@ha
lwz r5,(timebase_period_ns-0b)@l(r5)
add r4,r4,r5
addi r4,r4,-1
divw r4,r4,r5 /* BUS ticks */
1: MFTBU(r5)
MFTBL(r6)
MFTBU(r7)
cmpw 0,r5,r7
bne 1b /* Get [synced] base time */
addc r9,r6,r4 /* Compute end time */
addze r8,r5
2: MFTBU(r5)
cmpw 0,r5,r8
blt 2b
bgt 3f
MFTBL(r6)
cmpw 0,r6,r9
blt 2b
3: blr
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