1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
/*
* (C) Copyright 2007 Michal Simek
* (C) Copyright 2004 Atmark Techno, Inc.
*
* Michal SIMEK <monstr@monstr.eu>
* Yasushi SHOJI <yashi@atmark-techno.com>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <config.h>
.text
.global _start
_start:
mts rmsr, r0 /* disable cache */
addi r1, r0, CONFIG_SYS_INIT_SP_OFFSET
addi r1, r1, -4 /* Decrement SP to top of memory */
/* Find-out if u-boot is running on BIG/LITTLE endian platform
* There are some steps which is necessary to keep in mind:
* 1. Setup offset value to r6
* 2. Store word offset value to address 0x0
* 3. Load just byte from address 0x0
* 4a) LITTLE endian - r10 contains 0x2 because it is the smallest
* value that's why is on address 0x0
* 4b) BIG endian - r10 contains 0x0 because 0x2 offset is on addr 0x3
*/
addik r6, r0, 0x2 /* BIG/LITTLE endian offset */
swi r6, r0, 0
lbui r10, r0, 0
swi r6, r0, 0x40
swi r10, r0, 0x50
/* add opcode instruction for 32bit jump - 2 instruction imm & brai*/
addi r6, r0, 0xb0000000 /* hex b000 opcode imm */
swi r6, r0, 0x0 /* reset address */
swi r6, r0, 0x8 /* user vector exception */
swi r6, r0, 0x10 /* interrupt */
swi r6, r0, 0x20 /* hardware exception */
addi r6, r0, 0xb8080000 /* hew b808 opcode brai*/
swi r6, r0, 0x4 /* reset address */
swi r6, r0, 0xC /* user vector exception */
swi r6, r0, 0x14 /* interrupt */
swi r6, r0, 0x24 /* hardware exception */
#ifdef CONFIG_SYS_RESET_ADDRESS
/* reset address */
addik r6, r0, CONFIG_SYS_RESET_ADDRESS
sw r6, r1, r0
lhu r7, r1, r0
shi r7, r0, 0x2
shi r6, r0, 0x6
/*
* Copy U-Boot code to CONFIG_SYS_TEXT_BASE
* solve problem with sbrk_base
*/
#if (CONFIG_SYS_RESET_ADDRESS != CONFIG_SYS_TEXT_BASE)
addi r4, r0, __end
addi r5, r0, __text_start
rsub r4, r5, r4 /* size = __end - __text_start */
addi r6, r0, CONFIG_SYS_RESET_ADDRESS /* source address */
addi r7, r0, 0 /* counter */
4:
lw r8, r6, r7
sw r8, r5, r7
addi r7, r7, 0x4
cmp r8, r4, r7
blti r8, 4b
#endif
#endif
#ifdef CONFIG_SYS_USR_EXCEP
/* user_vector_exception */
addik r6, r0, _exception_handler
sw r6, r1, r0
/*
* BIG ENDIAN memory map for user exception
* 0x8: 0xB000XXXX
* 0xC: 0xB808XXXX
*
* then it is necessary to count address for storing the most significant
* 16bits from _exception_handler address and copy it to
* 0xa address. Big endian use offset in r10=0 that's why is it just
* 0xa address. The same is done for the least significant 16 bits
* for 0xe address.
*
* LITTLE ENDIAN memory map for user exception
* 0x8: 0xXXXX00B0
* 0xC: 0xXXXX08B8
*
* Offset is for little endian setup to 0x2. rsubi instruction decrease
* address value to ensure that points to proper place which is
* 0x8 for the most significant 16 bits and
* 0xC for the least significant 16 bits
*/
lhu r7, r1, r10
rsubi r8, r10, 0xa
sh r7, r0, r8
rsubi r8, r10, 0xe
sh r6, r0, r8
#endif
#ifdef CONFIG_SYS_INTC_0
/* interrupt_handler */
addik r6, r0, _interrupt_handler
sw r6, r1, r0
lhu r7, r1, r10
rsubi r8, r10, 0x12
sh r7, r0, r8
rsubi r8, r10, 0x16
sh r6, r0, r8
#endif
/* hardware exception */
addik r6, r0, _hw_exception_handler
sw r6, r1, r0
lhu r7, r1, r10
rsubi r8, r10, 0x22
sh r7, r0, r8
rsubi r8, r10, 0x26
sh r6, r0, r8
/* enable instruction and data cache */
mfs r12, rmsr
ori r12, r12, 0xa0
mts rmsr, r12
clear_bss:
/* clear BSS segments */
addi r5, r0, __bss_start
addi r4, r0, __bss_end
cmp r6, r5, r4
beqi r6, 3f
2:
swi r0, r5, 0 /* write zero to loc */
addi r5, r5, 4 /* increment to next loc */
cmp r6, r5, r4 /* check if we have reach the end */
bnei r6, 2b
3: /* jumping to board_init */
brai board_init
1: bri 1b
/*
* Read 16bit little endian
*/
.text
.global in16
.ent in16
.align 2
in16: lhu r3, r0, r5
bslli r4, r3, 8
bsrli r3, r3, 8
andi r4, r4, 0xffff
or r3, r3, r4
rtsd r15, 8
sext16 r3, r3
.end in16
/*
* Write 16bit little endian
* first parameter(r5) - address, second(r6) - short value
*/
.text
.global out16
.ent out16
.align 2
out16: bslli r3, r6, 8
bsrli r6, r6, 8
andi r3, r3, 0xffff
or r3, r3, r6
sh r3, r0, r5
rtsd r15, 8
or r0, r0, r0
.end out16
|
