| Mark A. Greer | 0c176fa | 2006-10-16 13:52:09 -0700 | [diff] [blame] | 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 |
| 36 | timebase_period_ns: |
| 37 | .long 60 |
| 38 | |
| 39 | .text |
| 40 | /* |
| 41 | * Delay for a number of microseconds |
| 42 | */ |
| 43 | .globl udelay |
| 44 | udelay: |
| 45 | mfspr r4,SPRN_PVR |
| 46 | srwi r4,r4,16 |
| 47 | cmpwi 0,r4,1 /* 601 ? */ |
| 48 | bne .udelay_not_601 |
| 49 | 00: li r0,86 /* Instructions / microsecond? */ |
| 50 | mtctr r0 |
| 51 | 10: 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 |
| 64 | 0: 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 */ |
| 74 | 1: 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 |
| 81 | 2: mftbu r5 |
| 82 | cmpw 0,r5,r8 |
| 83 | blt 2b |
| 84 | bgt 3f |
| 85 | mftb r6 |
| 86 | cmpw 0,r6,r9 |
| 87 | blt 2b |
| 88 | 3: blr |