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wdenk2262cfe2002-11-18 00:14:45 +00001/*
wdenk8bde7f72003-06-27 21:31:46 +00002 * U-boot - i386 Startup Code
wdenk2262cfe2002-11-18 00:14:45 +00003 *
4 * Copyright (c) 2002 Omicron Ceti AB, Daniel Engström <denaiel@omicron.se>
5 *
6 * See file CREDITS for list of people who contributed to this
7 * project.
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation; either version 2 of
12 * the License, or (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
22 * MA 02111-1307 USA
23 */
24
25
26#include <config.h>
27#include <version.h>
28
wdenk8bde7f72003-06-27 21:31:46 +000029
wdenk2262cfe2002-11-18 00:14:45 +000030.section .text
31.code32
32.globl _start
wdenk8bde7f72003-06-27 21:31:46 +000033.type _start, @function
wdenk2262cfe2002-11-18 00:14:45 +000034.globl _i386boot_start
35_i386boot_start:
Graeme Russ077e1952010-04-24 00:05:42 +100036 /*
37 * This is the fail safe 32-bit bootstrap entry point. The
38 * following code is not executed from a cold-reset (actually, a
39 * lot of it is, but from real-mode after cold reset. It is
40 * repeated here to put the board into a state as close to cold
41 * reset as necessary)
42 */
43 cli
44 cld
45
46 /* Turn of cache (this might require a 486-class CPU) */
47 movl %cr0, %eax
Graeme Russ8ffb2e82010-10-07 20:03:21 +110048 orl $0x60000000, %eax
Graeme Russ077e1952010-04-24 00:05:42 +100049 movl %eax, %cr0
50 wbinvd
51
52 /* Tell 32-bit code it is being entered from an in-RAM copy */
53 movw $0x0000, %bx
wdenk8bde7f72003-06-27 21:31:46 +000054_start:
Graeme Russ077e1952010-04-24 00:05:42 +100055 /* This is the 32-bit cold-reset entry point */
56
Graeme Russ8ffb2e82010-10-07 20:03:21 +110057 movl $0x18, %eax /* Load our segement registes, the
Wolfgang Denk53677ef2008-05-20 16:00:29 +020058 * gdt have already been loaded by start16.S */
Graeme Russ8ffb2e82010-10-07 20:03:21 +110059 movw %ax, %fs
60 movw %ax, %ds
61 movw %ax, %gs
62 movw %ax, %es
63 movw %ax, %ss
wdenk8bde7f72003-06-27 21:31:46 +000064
Graeme Russ077e1952010-04-24 00:05:42 +100065 /* Clear the interupt vectors */
66 lidt blank_idt_ptr
67
68 /*
69 * Skip low-level board and memory initialization if not starting
70 * from cold-reset. This allows us to do a fail safe boot-strap
71 * into a new build of U-Boot from a known-good boot flash
72 */
73 movw $0x0001, %ax
74 cmpw %ax, %bx
75 jne mem_init_ret
76
wdenk2262cfe2002-11-18 00:14:45 +000077 /* We call a few functions in the board support package
78 * since we have no stack yet we'll have to use %ebp
79 * to store the return address */
wdenk8bde7f72003-06-27 21:31:46 +000080
wdenk2262cfe2002-11-18 00:14:45 +000081 /* Early platform init (setup gpio, etc ) */
Graeme Russ8ffb2e82010-10-07 20:03:21 +110082 mov $early_board_init_ret, %ebp
wdenk2262cfe2002-11-18 00:14:45 +000083 jmp early_board_init
84early_board_init_ret:
wdenk8bde7f72003-06-27 21:31:46 +000085
wdenk2262cfe2002-11-18 00:14:45 +000086 /* size memory */
87 mov $mem_init_ret, %ebp
Graeme Russ8ffb2e82010-10-07 20:03:21 +110088 jmp mem_init
wdenk2262cfe2002-11-18 00:14:45 +000089mem_init_ret:
wdenk8bde7f72003-06-27 21:31:46 +000090
Graeme Russ759598f2010-04-24 00:05:41 +100091 /* fetch memory size (into %eax) */
92 mov $get_mem_size_ret, %ebp
Graeme Russ8ffb2e82010-10-07 20:03:21 +110093 jmp get_mem_size
Graeme Russ759598f2010-04-24 00:05:41 +100094get_mem_size_ret:
95
Graeme Russ1c409bc2009-11-24 20:04:21 +110096 /* Check we have enough memory for stack */
97 movl $CONFIG_SYS_STACK_SIZE, %ecx
wdenk8bde7f72003-06-27 21:31:46 +000098 cmpl %ecx, %eax
Graeme Russ6ae032a2010-10-07 20:03:24 +110099 jb die
wdenk8bde7f72003-06-27 21:31:46 +0000100mem_ok:
Graeme Russ1c409bc2009-11-24 20:04:21 +1100101 /* Set stack pointer to upper memory limit*/
Graeme Russ8ffb2e82010-10-07 20:03:21 +1100102 movl %eax, %esp
wdenk2262cfe2002-11-18 00:14:45 +0000103
Graeme Russ1c409bc2009-11-24 20:04:21 +1100104 /* Test the stack */
wdenk2262cfe2002-11-18 00:14:45 +0000105 pushl $0
106 popl %eax
107 cmpl $0, %eax
108 jne no_stack
109 push $0x55aa55aa
110 popl %ebx
111 cmpl $0x55aa55aa, %ebx
Graeme Russ6ae032a2010-10-07 20:03:24 +1100112 jne die
wdenk2262cfe2002-11-18 00:14:45 +0000113
wdenk8bde7f72003-06-27 21:31:46 +0000114 wbinvd
wdenk2262cfe2002-11-18 00:14:45 +0000115
Graeme Russ5c161652010-10-07 20:03:23 +1100116 /* Set the upper memory limit parameter */
117 movl %esp, %eax
118 subl $CONFIG_SYS_STACK_SIZE, %eax
wdenk2262cfe2002-11-18 00:14:45 +0000119
Graeme Russ1c409bc2009-11-24 20:04:21 +1100120 call board_init_f /* Enter, U-boot! */
wdenk2262cfe2002-11-18 00:14:45 +0000121
122 /* indicate (lack of) progress */
wdenk8bde7f72003-06-27 21:31:46 +0000123 movw $0x85, %ax
wdenk2262cfe2002-11-18 00:14:45 +0000124die: hlt
125 jmp die
wdenk8bde7f72003-06-27 21:31:46 +0000126 hlt
Graeme Russ077e1952010-04-24 00:05:42 +1000127
128blank_idt_ptr:
129 .word 0 /* limit */
130 .long 0 /* base */