summaryrefslogtreecommitdiff
path: root/cpu/i386/start.S
blob: afcbb24520b0631cfa574f15cad688d9221df7de (plain)
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
193
194
195
196
/*
 *  U-boot - i386 Startup Code
 *
 *  Copyright (c) 2002	Omicron Ceti AB, Daniel Engström <denaiel@omicron.se>
 *
 * 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>
#include <version.h>


.section .text
.code32
.globl _start
.type _start, @function
.globl _i386boot_start
_i386boot_start:
_start:
	movl    $0x18,%eax         	/* Load our segement registes, the
					 * gdt have already been loaded by start16.S */
	movw    %ax,%fs
	movw	%ax,%ds
	movw    %ax,%gs
	movw    %ax,%es
	movw    %ax,%ss

	/* We call a few functions in the board support package
	 * since we have no stack yet we'll have to use %ebp
	 * to store the return address */

	/* Early platform init (setup gpio, etc ) */
	mov     $early_board_init_ret, %ebp
	jmp	early_board_init
early_board_init_ret:

	/* The __port80 entry-point should be usabe by now */
	/* so we try to indicate progress */
	movw	$0x01, %ax
	movl	$.progress0, %ebp
	jmp	__show_boot_progress
.progress0:

	/* size memory */
	mov	$mem_init_ret, %ebp
	jmp     mem_init
mem_init_ret:

	/* check ammount of configured memory
	 * (we need atleast bss start+bss size+stack size) */
	movl	$_i386boot_bss_start, %ecx        /* BSS start */
	addl	$_i386boot_bss_size, %ecx         /* BSS size */
	addl	$CFG_STACK_SIZE, %ecx
	cmpl	%ecx, %eax
	jae	mem_ok

	/* indicate (lack of) progress */
	movw	$0x81, %ax
	movl	$.progress0a, %ebp
	jmp	__show_boot_progress
.progress0a:
	jmp 	die
mem_ok:

	/* indicate progress */
	movw	$0x02, %ax
	movl	$.progress1, %ebp
	jmp	__show_boot_progress
.progress1:

	/* create a stack after the bss */
	movl    $_i386boot_bss_start, %eax
	addl	$_i386boot_bss_size, %eax
	addl	$CFG_STACK_SIZE, %eax
	movl    %eax, %esp

	pushl	$0
	popl	%eax
	cmpl	$0, %eax
	jne	no_stack
	push	$0x55aa55aa
	popl	%ebx
	cmpl	$0x55aa55aa, %ebx
	je	stack_ok

no_stack:
	/* indicate (lack of) progress */
	movw	$0x82, %ax
	movl	$.progress1a, %ebp
	jmp	__show_boot_progress
.progress1a:
	jmp die


stack_ok:
	/* indicate progress */
	movw	$0x03, %ax
	movl	$.progress2, %ebp
	jmp	__show_boot_progress
.progress2:

	/* copy data section to ram, size must be 4-byte aligned */
	movl	$_i386boot_romdata_dest, %edi	  /* destination address */
	movl	$_i386boot_romdata_start, %esi	  /* source address */
	movl	$_i386boot_romdata_size, %ecx     /* number of bytes to copy */
	movl	%ecx, %eax
	andl	$3, %eax
	jnz	data_fail

	shrl	$2, %ecx	                  /* copy 4 byte each time */
	cld
	cmpl	$0, %ecx
	je	data_ok
data_segment:
	movsl
	loop	data_segment
	jmp	data_ok
data_fail:
	/* indicate (lack of) progress */
	movw	$0x83, %ax
	movl	$.progress2a, %ebp
	jmp	__show_boot_progress
.progress2a:
	jmp 	die

data_ok:

	/* indicate progress */
	movw	$0x04, %ax
	movl	$.progress3, %ebp
	jmp	__show_boot_progress
.progress3:

	/* clear bss section in ram, size must be 4-byte aligned  */
	movl	$_i386boot_bss_start, %eax        /* BSS start */
	movl	$_i386boot_bss_size, %ecx         /* BSS size */
	movl	%ecx, %eax
	andl	$3, %eax
	jnz	bss_fail
	shrl	$2, %ecx	                  /* clear 4 byte each time */
	cld
	cmpl	$0, %ecx
	je	bss_ok
bss:
	movl	$0, (%edi)
	add	$4, %edi
	loop	bss
	jmp 	bss_ok

bss_fail:
	/* indicate (lack of) progress */
	movw	$0x84, %ax
	movl	$.progress3a, %ebp
	jmp	__show_boot_progress
.progress3a:
	jmp 	die

bss_ok:

	wbinvd


	/* indicate progress */
	movw	$0x05, %ax
	movl	$.progress4, %ebp
	jmp	__show_boot_progress
.progress4:

	call	start_i386boot  /* Enter, U-boot! */

	/* indicate (lack of) progress */
	movw	$0x85, %ax
	movl	$.progress4a, %ebp
	jmp	__show_boot_progress
.progress4a:

die:	hlt
	jmp	die
	hlt