xref: /linux/arch/powerpc/boot/gamecube-head.S (revision 4e95bc268b915c3a19ec8b9110f61e4ea41a1ed0) 
1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * arch/powerpc/boot/gamecube-head.S
4 *
5 * Nintendo GameCube bootwrapper entry.
6 * Copyright (C) 2004-2009 The GameCube Linux Team
7 * Copyright (C) 2008,2009 Albert Herranz
8 */
9
10#include "ppc_asm.h"
11
12/*
13 * The entry code does no assumptions regarding:
14 * - if the data and instruction caches are enabled or not
15 * - if the MMU is enabled or not
16 *
17 * We enable the caches if not already enabled, enable the MMU with an
18 * identity mapping scheme and jump to the start code.
19 */
20
21	.text
22
23	.globl _zimage_start
24_zimage_start:
25
26	/* turn the MMU off */
27	mfmsr	9
28	rlwinm	9, 9, 0, ~((1<<4)|(1<<5)) /* MSR_DR|MSR_IR */
29	bcl	20, 31, 1f
301:
31	mflr	8
32	clrlwi	8, 8, 3		/* convert to a real address */
33	addi	8, 8, _mmu_off - 1b
34	mtsrr0	8
35	mtsrr1	9
36	rfi
37_mmu_off:
38	/* MMU disabled */
39
40	/* setup BATs */
41	isync
42	li      8, 0
43	mtspr	0x210, 8	/* IBAT0U */
44	mtspr	0x212, 8	/* IBAT1U */
45	mtspr	0x214, 8	/* IBAT2U */
46	mtspr	0x216, 8	/* IBAT3U */
47	mtspr	0x218, 8	/* DBAT0U */
48	mtspr	0x21a, 8	/* DBAT1U */
49	mtspr	0x21c, 8	/* DBAT2U */
50	mtspr	0x21e, 8	/* DBAT3U */
51
52	li	8, 0x01ff	/* first 16MiB */
53	li	9, 0x0002	/* rw */
54	mtspr	0x211, 9	/* IBAT0L */
55	mtspr	0x210, 8	/* IBAT0U */
56	mtspr	0x219, 9	/* DBAT0L */
57	mtspr	0x218, 8	/* DBAT0U */
58
59	lis	8, 0x0c00	/* I/O mem */
60	ori	8, 8, 0x3ff	/* 32MiB */
61	lis	9, 0x0c00
62	ori	9, 9, 0x002a	/* uncached, guarded, rw */
63	mtspr	0x21b, 9	/* DBAT1L */
64	mtspr	0x21a, 8	/* DBAT1U */
65
66	lis	8, 0x0100	/* next 8MiB */
67	ori	8, 8, 0x00ff	/* 8MiB */
68	lis	9, 0x0100
69	ori	9, 9, 0x0002	/* rw */
70	mtspr	0x215, 9	/* IBAT2L */
71	mtspr	0x214, 8	/* IBAT2U */
72	mtspr	0x21d, 9	/* DBAT2L */
73	mtspr	0x21c, 8	/* DBAT2U */
74
75	/* enable and invalidate the caches if not already enabled */
76	mfspr	8, 0x3f0	/* HID0 */
77	andi.	0, 8, (1<<15)		/* HID0_ICE */
78	bne	1f
79	ori	8, 8, (1<<15)|(1<<11)	/* HID0_ICE|HID0_ICFI*/
801:
81	andi.	0, 8, (1<<14)		/* HID0_DCE */
82	bne	1f
83	ori	8, 8, (1<<14)|(1<<10)	/* HID0_DCE|HID0_DCFI*/
841:
85	mtspr	0x3f0, 8	/* HID0 */
86	isync
87
88	/* initialize arguments */
89	li	3, 0
90	li	4, 0
91	li	5, 0
92
93	/* turn the MMU on */
94	bcl	20, 31, 1f
951:
96	mflr	8
97	addi	8, 8, _mmu_on - 1b
98	mfmsr	9
99	ori	9, 9, (1<<4)|(1<<5) /* MSR_DR|MSR_IR */
100	mtsrr0	8
101	mtsrr1	9
102	sync
103	rfi
104_mmu_on:
105	b _zimage_start_lib
106
107