| /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| /* |
| * 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 |
| */ |
| #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 */ |
| 1: MFTBU(r5) |
| MFTBL(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 |
| MFTBL(r6) |
| cmpw 0,r6,r9 |
| blt 2b |
| 3: blr |
