diff options
Diffstat (limited to 'arch/powerpc/boot/util.S')
| -rw-r--r-- | arch/powerpc/boot/util.S | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/arch/powerpc/boot/util.S b/arch/powerpc/boot/util.S new file mode 100644 index 000000000000..427ddfc11991 --- /dev/null +++ b/arch/powerpc/boot/util.S @@ -0,0 +1,88 @@ +/* + * 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 |