1/*-
2 * Copyright (c) 2008 Semihalf, Rafal Czubak
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD$
27 */
28
29#include <machine/asm.h>
30
31/*
32 * Entry point to the loader that U-Boot passes control to.
33 */
34	.text
35	.globl	_start
36_start:
37	/* Hint where to look for the API signature */
38	ldr	ip, =uboot_address
39	str	sp, [ip]
40
41	/* Save U-Boot's r8 */
42	ldr	ip, =saved_regs
43	str	r8, [ip, #0]
44
45	/* Start loader */
46	b	main
47
48/*
49 * syscall()
50 */
51ENTRY(syscall)
52	/* Save caller's lr */
53	ldr	ip, =saved_regs
54	str	lr, [ip, #4]
55	/* Save loader's r8 */
56	ldr	ip, =saved_regs
57	str	r8, [ip, #8]
58
59	/* Restore U-Boot's r8 */
60	ldr	ip, =saved_regs
61	ldr	r8, [ip, #0]
62	/* Call into U-Boot */
63	ldr	lr, =return_from_syscall
64	ldr	ip, =syscall_ptr
65	ldr	pc, [ip]
66
67return_from_syscall:
68	/* Restore loader's r8 */
69	ldr	ip, =saved_regs
70	ldr	r8, [ip, #8]
71	/* Restore caller's lr */
72	ldr	ip, =saved_regs
73	ldr	lr, [ip, #4]
74	/* Return to caller */
75	mov	pc, lr
76
77/*
78 * Data section
79 */
80	.data
81	.align	4
82	.globl	syscall_ptr
83syscall_ptr:
84	.long	0
85
86	.globl	uboot_address
87uboot_address:
88	.long	0
89
90saved_regs:
91	.long	0	/* U-Boot's r8 */
92	.long	0	/* Loader's r8 */
93	.long	0	/* Loader's lr */
94