1/* 2 * Copied from <file:arch/powerpc/kernel/misc_32.S> 3 * 4 * This file contains miscellaneous low-level functions. 5 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) 6 * 7 * Largely rewritten by Cort Dougan (cort@cs.nmt.edu) 8 * and Paul Mackerras. 9 * 10 * kexec bits: 11 * Copyright (C) 2002-2003 Eric Biederman <ebiederm@xmission.com> 12 * GameCube/ppc32 port Copyright (C) 2004 Albert Herranz 13 * 14 * This program is free software; you can redistribute it and/or 15 * modify it under the terms of the GNU General Public License 16 * as published by the Free Software Foundation; either version 17 * 2 of the License, or (at your option) any later version. 18 * 19 */ 20#include "ppc_asm.h" 21 22#define SPRN_PVR 0x11F /* Processor Version Register */ 23 24 .text 25 26/* udelay (on non-601 processors) needs to know the period of the 27 * timebase in nanoseconds. This used to be hardcoded to be 60ns 28 * (period of 66MHz/4). Now a variable is used that is initialized to 29 * 60 for backward compatibility, but it can be overridden as necessary 30 * with code something like this: 31 * extern unsigned long timebase_period_ns; 32 * timebase_period_ns = 1000000000 / bd->bi_tbfreq; 33 */ 34 .data 35 .globl timebase_period_ns 36timebase_period_ns: 37 .long 60 38 39 .text 40/* 41 * Delay for a number of microseconds 42 */ 43 .globl udelay 44udelay: 45 mfspr r4,SPRN_PVR 46 srwi r4,r4,16 47 cmpwi 0,r4,1 /* 601 ? */ 48 bne .udelay_not_601 4900: li r0,86 /* Instructions / microsecond? */ 50 mtctr r0 5110: addi r0,r0,0 /* NOP */ 52 bdnz 10b 53 subic. r3,r3,1 54 bne 00b 55 blr 56 57.udelay_not_601: 58 mulli r4,r3,1000 /* nanoseconds */ 59 /* Change r4 to be the number of ticks using: 60 * (nanoseconds + (timebase_period_ns - 1 )) / timebase_period_ns 61 * timebase_period_ns defaults to 60 (16.6MHz) */ 62 mflr r5 63 bl 0f 640: mflr r6 65 mtlr r5 66 lis r5,0b@ha 67 addi r5,r5,0b@l 68 subf r5,r5,r6 /* In case we're relocated */ 69 addis r5,r5,timebase_period_ns@ha 70 lwz r5,timebase_period_ns@l(r5) 71 add r4,r4,r5 72 addi r4,r4,-1 73 divw r4,r4,r5 /* BUS ticks */ 741: mftbu r5 75 mftb r6 76 mftbu r7 77 cmpw 0,r5,r7 78 bne 1b /* Get [synced] base time */ 79 addc r9,r6,r4 /* Compute end time */ 80 addze r8,r5 812: mftbu r5 82 cmpw 0,r5,r8 83 blt 2b 84 bgt 3f 85 mftb r6 86 cmpw 0,r6,r9 87 blt 2b 883: blr 89