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| /*
| * Copied from <file:arch/powerpc/kernel/misc_32.S>
| *
| * This file contains miscellaneous low-level functions.
| * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
| *
| * Largely rewritten by Cort Dougan (cort@cs.nmt.edu)
| * and Paul Mackerras.
| *
| * kexec bits:
| * Copyright (C) 2002-2003 Eric Biederman <ebiederm@xmission.com>
| * GameCube/ppc32 port Copyright (C) 2004 Albert Herranz
| *
| * 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.
| *
| */
| #include "ppc_asm.h"
|
| #define SPRN_PVR 0x11F /* Processor Version Register */
|
| .text
|
| /* udelay (on non-601 processors) 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:
| mfspr r4,SPRN_PVR
| srwi r4,r4,16
| cmpwi 0,r4,1 /* 601 ? */
| bne .Ludelay_not_601
| 00: li r0,86 /* Instructions / microsecond? */
| mtctr r0
| 10: addi r0,r0,0 /* NOP */
| bdnz 10b
| subic. r3,r3,1
| bne 00b
| blr
|
| .Ludelay_not_601:
| 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
| bl 0f
| 0: mflr r6
| mtlr r5
| lis r5,0b@ha
| addi r5,r5,0b@l
| subf r5,r5,r6 /* In case we're relocated */
| addis r5,r5,timebase_period_ns@ha
| lwz r5,timebase_period_ns@l(r5)
| add r4,r4,r5
| addi r4,r4,-1
| divw r4,r4,r5 /* BUS ticks */
| #ifdef CONFIG_8xx
| 1: mftbu r5
| mftb r6
| mftbu r7
| #else
| 1: mfspr r5, SPRN_TBRU
| mfspr r6, SPRN_TBRL
| mfspr r7, SPRN_TBRU
| #endif
| cmpw 0,r5,r7
| bne 1b /* Get [synced] base time */
| addc r9,r6,r4 /* Compute end time */
| addze r8,r5
| #ifdef CONFIG_8xx
| 2: mftbu r5
| #else
| 2: mfspr r5, SPRN_TBRU
| #endif
| cmpw 0,r5,r8
| blt 2b
| bgt 3f
| #ifdef CONFIG_8xx
| mftb r6
| #else
| mfspr r6, SPRN_TBRL
| #endif
| cmpw 0,r6,r9
| blt 2b
| 3: blr
|
|
