blob: 2a5cca9d69ac86f64ef5b7b839267071a973d913 [file] [log] [blame]
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 *
wdenk7a8e9bed2003-05-31 18:35:21 +00004 * Copyright (c) 2002, 2003 Omicron Ceti AB, Daniel Engström <denaiel@omicron.se>
wdenk2262cfe2002-11-18 00:14:45 +00005 *
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#define BOOT_SEG 0xffff0000 /* linear segment of boot code */
27#define a32 .byte 0x67;
28#define o32 .byte 0x66;
29
30.section .start16, "ax"
31.code16
32.globl start16
wdenk8bde7f72003-06-27 21:31:46 +000033start16:
Graeme Russ8ffb2e82010-10-07 20:03:21 +110034 /*
35 * First we let the BSP do some early initialization
wdenk2262cfe2002-11-18 00:14:45 +000036 * this code have to map the flash to its final position
37 */
38 mov $board_init16_ret, %bp
39 jmp board_init16
wdenk8bde7f72003-06-27 21:31:46 +000040board_init16_ret:
41
wdenk2262cfe2002-11-18 00:14:45 +000042 /* Turn of cache (this might require a 486-class CPU) */
Wolfgang Denk53677ef2008-05-20 16:00:29 +020043 movl %cr0, %eax
Graeme Russ8ffb2e82010-10-07 20:03:21 +110044 orl $0x60000000, %eax
Wolfgang Denk53677ef2008-05-20 16:00:29 +020045 movl %eax, %cr0
wdenk8bde7f72003-06-27 21:31:46 +000046 wbinvd
47
Graeme Russc14a3662010-04-24 00:05:43 +100048 /* load the temporary Global Descriptor Table */
Graeme Russ797960f2010-08-22 16:25:59 +100049o32 cs lidt idt_ptr
Wolfgang Denk53677ef2008-05-20 16:00:29 +020050o32 cs lgdt gdt_ptr
wdenk2262cfe2002-11-18 00:14:45 +000051
wdenk2262cfe2002-11-18 00:14:45 +000052 /* Now, we enter protected mode */
Wolfgang Denk53677ef2008-05-20 16:00:29 +020053 movl %cr0, %eax
Graeme Russ8ffb2e82010-10-07 20:03:21 +110054 orl $1, %eax
Wolfgang Denk53677ef2008-05-20 16:00:29 +020055 movl %eax, %cr0
wdenk8bde7f72003-06-27 21:31:46 +000056
wdenk2262cfe2002-11-18 00:14:45 +000057 /* Flush the prefetch queue */
Wolfgang Denk53677ef2008-05-20 16:00:29 +020058 jmp ff
wdenk2262cfe2002-11-18 00:14:45 +000059ff:
Graeme Russ077e1952010-04-24 00:05:42 +100060 /* Tell 32-bit code it is being entered from hard-reset */
61 movw $0x0001, %bx
wdenk2262cfe2002-11-18 00:14:45 +000062
63 /* Finally jump to the 32bit initialization code */
wdenk8bde7f72003-06-27 21:31:46 +000064 movw $code32start, %ax
Graeme Russ8ffb2e82010-10-07 20:03:21 +110065 movw %ax, %bp
wdenk2262cfe2002-11-18 00:14:45 +000066o32 cs ljmp *(%bp)
67
68 /* 48-bit far pointer */
69code32start:
Wolfgang Denk53677ef2008-05-20 16:00:29 +020070 .long _start /* offset */
71 .word 0x10 /* segment */
wdenk2262cfe2002-11-18 00:14:45 +000072
Graeme Russ797960f2010-08-22 16:25:59 +100073idt_ptr:
74 .word 0 /* limit */
75 .long 0 /* base */
76
Graeme Russc14a3662010-04-24 00:05:43 +100077/*
78 * The following Global Descriptor Table is just enough to get us into
79 * 'Flat Protected Mode' - It will be discarded as soon as the final
80 * GDT is setup in a safe location in RAM
81 */
wdenk2262cfe2002-11-18 00:14:45 +000082gdt_ptr:
Graeme Russc14a3662010-04-24 00:05:43 +100083 .word 0x20 /* limit (32 bytes = 4 GDT entries) */
Wolfgang Denk53677ef2008-05-20 16:00:29 +020084 .long BOOT_SEG + gdt /* base */
wdenk2262cfe2002-11-18 00:14:45 +000085
wdenk8bde7f72003-06-27 21:31:46 +000086 /* The GDT table ...
wdenk2262cfe2002-11-18 00:14:45 +000087 *
Wolfgang Denk53677ef2008-05-20 16:00:29 +020088 * Selector Type
89 * 0x00 NULL
90 * 0x08 Unused
wdenk8bde7f72003-06-27 21:31:46 +000091 * 0x10 32bit code
wdenk2262cfe2002-11-18 00:14:45 +000092 * 0x18 32bit data/stack
wdenk2262cfe2002-11-18 00:14:45 +000093 */
94
95gdt:
Wolfgang Denk53677ef2008-05-20 16:00:29 +020096 .word 0, 0, 0, 0 /* NULL */
97 .word 0, 0, 0, 0 /* unused */
wdenk2262cfe2002-11-18 00:14:45 +000098
Wolfgang Denk53677ef2008-05-20 16:00:29 +020099 .word 0xFFFF /* 4Gb - (0x100000*0x1000 = 4Gb) */
100 .word 0 /* base address = 0 */
101 .word 0x9B00 /* code read/exec */
102 .word 0x00CF /* granularity = 4096, 386 (+5th nibble of limit) */
wdenk2262cfe2002-11-18 00:14:45 +0000103
Wolfgang Denk53677ef2008-05-20 16:00:29 +0200104 .word 0xFFFF /* 4Gb - (0x100000*0x1000 = 4Gb) */
105 .word 0x0 /* base address = 0 */
106 .word 0x9300 /* data read/write */
107 .word 0x00CF /* granularity = 4096, 386 (+5th nibble of limit) */