/* * 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 .udelay_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 .udelay_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 */ 1: mftbu r5 mftb 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 mftb r6 cmpw 0,r6,r9 blt 2b 3: blr