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#include "ppc_asm.h"
16
17#define SPRN_PVR        0x11F   /* Processor Version Register */
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
31timebase_period_ns:
32	.long	60
33
34	.text
35/*
36 * Delay for a number of microseconds
37 */
38	.globl	udelay
39udelay:
 
 
 
 
 
 
 
 
 
 
 
 
 
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
460:	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 */
531:	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
602:	MFTBU(r5)
 
 
 
 
61	cmpw	0,r5,r8
62	blt	2b
63	bgt	3f
64	MFTBL(r6)
 
 
 
 
65	cmpw	0,r6,r9
66	blt	2b
673:	blr

 
  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	.Ludelay_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.Ludelay_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 */
 74#ifdef CONFIG_8xx
 751:	mftbu	r5
 76	mftb	r6
 77	mftbu	r7
 78#else
 791:	mfspr	r5, SPRN_TBRU
 80	mfspr	r6, SPRN_TBRL
 81	mfspr	r7, SPRN_TBRU
 82#endif
 83	cmpw	0,r5,r7
 84	bne	1b		/* Get [synced] base time */
 85	addc	r9,r6,r4	/* Compute end time */
 86	addze	r8,r5
 87#ifdef CONFIG_8xx
 882:	mftbu	r5
 89#else
 902:	mfspr	r5, SPRN_TBRU
 91#endif
 92	cmpw	0,r5,r8
 93	blt	2b
 94	bgt	3f
 95#ifdef CONFIG_8xx
 96	mftb	r6
 97#else
 98	mfspr	r6, SPRN_TBRL
 99#endif
100	cmpw	0,r6,r9
101	blt	2b
1023:	blr