| 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */
|
| 2 | /*
|
| 3 | * Copied from <file:arch/powerpc/kernel/misc_32.S>
|
| 4 | *
|
| 5 | * This file contains miscellaneous low-level functions.
|
| 6 | * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
|
| 7 | *
|
| 8 | * Largely rewritten by Cort Dougan (cort@cs.nmt.edu)
|
| 9 | * and Paul Mackerras.
|
| 10 | *
|
| 11 | * kexec bits:
|
| 12 | * Copyright (C) 2002-2003 Eric Biederman <ebiederm@xmission.com>
|
| 13 | * GameCube/ppc32 port Copyright (C) 2004 Albert Herranz
|
| 14 | */
|
| 15 | |
| 16 |
|
| 17 | |
| 18 |
|
| 19 | .text
|
| 20 |
|
| 21 | /* udelay needs to know the period of the
|
| 22 | * timebase in nanoseconds. This used to be hardcoded to be 60ns
|
| 23 | * (period of 66MHz/4). Now a variable is used that is initialized to
|
| 24 | * 60 for backward compatibility, but it can be overridden as necessary
|
| 25 | * with code something like this:
|
| 26 | * extern unsigned long timebase_period_ns;
|
| 27 | * timebase_period_ns = 1000000000 / bd->bi_tbfreq;
|
| 28 | */
|
| 29 | .data
|
| 30 | .globl timebase_period_ns
|
| 31 | timebase_period_ns:
|
| 32 | .long 60
|
| 33 |
|
| 34 | .text
|
| 35 | /*
|
| 36 | * Delay for a number of microseconds
|
| 37 | */
|
| 38 | .globl udelay
|
| 39 | udelay:
|
| 40 | mulli r4,r3,1000 /* nanoseconds */
|
| 41 | /* Change r4 to be the number of ticks using:
|
| 42 | * (nanoseconds + (timebase_period_ns - 1 )) / timebase_period_ns
|
| 43 | * timebase_period_ns defaults to 60 (16.6MHz) */
|
| 44 | mflr r5
|
| 45 | bcl 20,31,0f
|
| 46 | 0: mflr r6
|
| 47 | mtlr r5
|
| 48 | addis r5,r6,(timebase_period_ns-0b)@ha
|
| 49 | lwz r5,(timebase_period_ns-0b)@l(r5)
|
| 50 | add r4,r4,r5
|
| 51 | addi r4,r4,-1
|
| 52 | divw r4,r4,r5 /* BUS ticks */
|
| 53 | 1: MFTBU(r5)
|
| 54 | MFTBL(r6)
|
| 55 | MFTBU(r7)
|
| 56 | cmpw 0,r5,r7
|
| 57 | bne 1b /* Get [synced] base time */
|
| 58 | addc r9,r6,r4 /* Compute end time */
|
| 59 | addze r8,r5
|
| 60 | 2: MFTBU(r5)
|
| 61 | cmpw 0,r5,r8
|
| 62 | blt 2b
|
| 63 | bgt 3f
|
| 64 | MFTBL(r6)
|
| 65 | cmpw 0,r6,r9
|
| 66 | blt 2b
|
| 67 | 3: blr
|