| /* |
| * U-boot - x86 Startup Code |
| * |
| * (C) Copyright 2008-2011 |
| * Graeme Russ, <graeme.russ@gmail.com> |
| * |
| * (C) Copyright 2002,2003 |
| * Daniel Engström, Omicron Ceti AB, <daniel@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 <asm/global_data.h> |
| #include <asm/processor-flags.h> |
| |
| #define BOOT_SEG 0xffff0000 /* linear segment of boot code */ |
| #define a32 .byte 0x67; |
| #define o32 .byte 0x66; |
| |
| .section .start16, "ax" |
| .code16 |
| .globl start16 |
| start16: |
| /* Set the Cold Boot / Hard Reset flag */ |
| movl $GD_FLG_COLD_BOOT, %ebx |
| |
| /* |
| * First we let the BSP do some early initialization |
| * this code have to map the flash to its final position |
| */ |
| jmp board_init16 |
| .globl board_init16_ret |
| board_init16_ret: |
| |
| /* Turn of cache (this might require a 486-class CPU) */ |
| movl %cr0, %eax |
| orl $(X86_CR0_NW & X86_CR0_CD), %eax |
| movl %eax, %cr0 |
| wbinvd |
| |
| /* load the temporary Global Descriptor Table */ |
| o32 cs lidt idt_ptr |
| o32 cs lgdt gdt_ptr |
| |
| /* Now, we enter protected mode */ |
| movl %cr0, %eax |
| orl $X86_CR0_PE, %eax |
| movl %eax, %cr0 |
| |
| /* Flush the prefetch queue */ |
| jmp ff |
| ff: |
| /* Finally jump to the 32bit initialization code */ |
| movw $code32start, %ax |
| movw %ax, %bp |
| o32 cs ljmp *(%bp) |
| |
| /* 48-bit far pointer */ |
| code32start: |
| .long _start /* offset */ |
| .word 0x10 /* segment */ |
| |
| idt_ptr: |
| .word 0 /* limit */ |
| .long 0 /* base */ |
| |
| /* |
| * The following Global Descriptor Table is just enough to get us into |
| * 'Flat Protected Mode' - It will be discarded as soon as the final |
| * GDT is setup in a safe location in RAM |
| */ |
| gdt_ptr: |
| .word 0x20 /* limit (32 bytes = 4 GDT entries) */ |
| .long BOOT_SEG + gdt /* base */ |
| |
| /* The GDT table ... |
| * |
| * Selector Type |
| * 0x00 NULL |
| * 0x08 Unused |
| * 0x10 32bit code |
| * 0x18 32bit data/stack |
| */ |
| |
| gdt: |
| .word 0, 0, 0, 0 /* NULL */ |
| .word 0, 0, 0, 0 /* unused */ |
| |
| .word 0xFFFF /* 4Gb - (0x100000*0x1000 = 4Gb) */ |
| .word 0 /* base address = 0 */ |
| .word 0x9B00 /* code read/exec */ |
| .word 0x00CF /* granularity = 4096, 386 (+5th nibble of limit) */ |
| |
| .word 0xFFFF /* 4Gb - (0x100000*0x1000 = 4Gb) */ |
| .word 0x0 /* base address = 0 */ |
| .word 0x9300 /* data read/write */ |
| .word 0x00CF /* granularity = 4096, 386 (+5th nibble of limit) */ |