1*4882a593Smuzhiyun/* SPDX-License-Identifier: GPL-2.0-or-later */ 2*4882a593Smuzhiyun/* 3*4882a593Smuzhiyun * Copied from <file:arch/powerpc/kernel/misc_32.S> 4*4882a593Smuzhiyun * 5*4882a593Smuzhiyun * This file contains miscellaneous low-level functions. 6*4882a593Smuzhiyun * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) 7*4882a593Smuzhiyun * 8*4882a593Smuzhiyun * Largely rewritten by Cort Dougan (cort@cs.nmt.edu) 9*4882a593Smuzhiyun * and Paul Mackerras. 10*4882a593Smuzhiyun * 11*4882a593Smuzhiyun * kexec bits: 12*4882a593Smuzhiyun * Copyright (C) 2002-2003 Eric Biederman <ebiederm@xmission.com> 13*4882a593Smuzhiyun * GameCube/ppc32 port Copyright (C) 2004 Albert Herranz 14*4882a593Smuzhiyun */ 15*4882a593Smuzhiyun#include "ppc_asm.h" 16*4882a593Smuzhiyun 17*4882a593Smuzhiyun#define SPRN_PVR 0x11F /* Processor Version Register */ 18*4882a593Smuzhiyun 19*4882a593Smuzhiyun .text 20*4882a593Smuzhiyun 21*4882a593Smuzhiyun/* udelay needs to know the period of the 22*4882a593Smuzhiyun * timebase in nanoseconds. This used to be hardcoded to be 60ns 23*4882a593Smuzhiyun * (period of 66MHz/4). Now a variable is used that is initialized to 24*4882a593Smuzhiyun * 60 for backward compatibility, but it can be overridden as necessary 25*4882a593Smuzhiyun * with code something like this: 26*4882a593Smuzhiyun * extern unsigned long timebase_period_ns; 27*4882a593Smuzhiyun * timebase_period_ns = 1000000000 / bd->bi_tbfreq; 28*4882a593Smuzhiyun */ 29*4882a593Smuzhiyun .data 30*4882a593Smuzhiyun .globl timebase_period_ns 31*4882a593Smuzhiyuntimebase_period_ns: 32*4882a593Smuzhiyun .long 60 33*4882a593Smuzhiyun 34*4882a593Smuzhiyun .text 35*4882a593Smuzhiyun/* 36*4882a593Smuzhiyun * Delay for a number of microseconds 37*4882a593Smuzhiyun */ 38*4882a593Smuzhiyun .globl udelay 39*4882a593Smuzhiyunudelay: 40*4882a593Smuzhiyun mulli r4,r3,1000 /* nanoseconds */ 41*4882a593Smuzhiyun /* Change r4 to be the number of ticks using: 42*4882a593Smuzhiyun * (nanoseconds + (timebase_period_ns - 1 )) / timebase_period_ns 43*4882a593Smuzhiyun * timebase_period_ns defaults to 60 (16.6MHz) */ 44*4882a593Smuzhiyun mflr r5 45*4882a593Smuzhiyun bl 0f 46*4882a593Smuzhiyun0: mflr r6 47*4882a593Smuzhiyun mtlr r5 48*4882a593Smuzhiyun lis r5,0b@ha 49*4882a593Smuzhiyun addi r5,r5,0b@l 50*4882a593Smuzhiyun subf r5,r5,r6 /* In case we're relocated */ 51*4882a593Smuzhiyun addis r5,r5,timebase_period_ns@ha 52*4882a593Smuzhiyun lwz r5,timebase_period_ns@l(r5) 53*4882a593Smuzhiyun add r4,r4,r5 54*4882a593Smuzhiyun addi r4,r4,-1 55*4882a593Smuzhiyun divw r4,r4,r5 /* BUS ticks */ 56*4882a593Smuzhiyun1: MFTBU(r5) 57*4882a593Smuzhiyun MFTBL(r6) 58*4882a593Smuzhiyun MFTBU(r7) 59*4882a593Smuzhiyun cmpw 0,r5,r7 60*4882a593Smuzhiyun bne 1b /* Get [synced] base time */ 61*4882a593Smuzhiyun addc r9,r6,r4 /* Compute end time */ 62*4882a593Smuzhiyun addze r8,r5 63*4882a593Smuzhiyun2: MFTBU(r5) 64*4882a593Smuzhiyun cmpw 0,r5,r8 65*4882a593Smuzhiyun blt 2b 66*4882a593Smuzhiyun bgt 3f 67*4882a593Smuzhiyun MFTBL(r6) 68*4882a593Smuzhiyun cmpw 0,r6,r9 69*4882a593Smuzhiyun blt 2b 70*4882a593Smuzhiyun3: blr 71