xref: /freebsd/stand/powerpc/ofw/trampolineLE.S (revision 7ab1a32cd43cbae61ad4dd435d6a482bbf61cb52)
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2020 Brandon Bergren <bdragon@FreeBSD.org>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <machine/asm.h>
29
30/**
31 * int openfirmware_trampoline(void *buf, int (*cb)(void *));
32 */
33ASENTRY_NOPROF(openfirmware_trampoline)
34	mflr	%r0
35	stw	%r0, 4(%r1)
36	stwu	%r1, -16(%r1)
37	stw	%r30, 8(%r1)
38	/* Save current MSR for restoration post-call. */
39	mfmsr	%r30
40	mr	%r5, %r30
41	/* Remove LE bit from MSR. */
42	clrrwi	%r5, %r5, 1
43	mtsrr0	%r4
44	mtsrr1	%r5
45	LOAD_LR_NIA
461:
47	mflr	%r4
48	addi	%r4, %r4, (2f - 1b)
49	mtlr	%r4
50	/* Switch to BE and transfer control to OF entry */
51	rfid
522:
53	/* Control is returned here, but in BE. */
54	.long	0x05009f42	/* LOAD_LR_NIA				*/
55				/* 0:					*/
56	.long	0xa603db7f	/* mtsrr1 	%r30			*/
57	.long	0xa602c87f	/* mflr		%r30			*/
58	.long	0x1400de3b	/* addi		%r30, %r30, (1f - 0b)	*/
59	.long	0xa603da7f	/* mtsrr0	%r30			*/
60	.long	0x2400004c	/* rfid					*/
61				/* 1:					*/
621:
63	/* Back to normal. Tidy up for return. */
64	lwz	%r30, 8(%r1)
65	lwz	%r0, 20(%r1)
66	addi	%r1, %r1, 16
67	mtlr	%r0
68	blr
69ASEND(openfirmware_trampoline)
70