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/*
* <boot.S>
*
* First stage BIOS loader for Open Hack'Ware.
*
* Copyright (C) 2004-2005 Jocelyn Mayer (l_indien@magic.fr)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License V2
* as published by the Free Software Foundation
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/*
* setup one RAM bank then
* relocate the one page BIOS second stage into RAM.
*
* We consider that we know nothing about the CPU state
* at the time we enter this code.
*
*/
#define ASSEMBLY_CODE
#include "bios.h"
.section .rom, "ax"
.align 2
_boot_start:
/* Minimal setup */
li r0, 0 ;
/* r11 is _boot_start address */
mflr r11 ;
addi r11, r11, (_boot_start - _start - 4) ;
/* Disable MMU and interruptions */
addi r12, r11, (_boot_no_mmu - _boot_start) ;
mtspr SRR0, r12 ;
mfmsr r12 ;
lis r13, 0x0004 ;
ori r13, r13, 0xEF71 ;
andc r15, r12, r13 ;
mtspr SRR1, r12 ;
rfi ;
_boot_no_mmu:
/* TODO: initialize physical RAM (we need at least one page)
* before doing anything else.
* This may be machine dependent code.
*/
_boot_copy:
/* Copy the second stage bootloader into RAM
* We may need a tiny driver if we need to boot from special device
* (ie disc-on-chip, ...)
*/
lis r12, (VECTORS_SIZE / 4)@h ;
ori r12, r12, (VECTORS_SIZE / 4)@l ;
mtctr r12 ;
clrrwi r12, r11, BIOS_IMAGE_BITS ;
addis r3, r12, VECTORS_SIZE@h ;
addi r3, r3, VECTORS_SIZE@l ;
subi r12, r12, 4 ;
lis r13, VECTORS_BASE@h ;
ori r13, r13, VECTORS_BASE@l ;
mtlr r13 ;
subi r13, r13, 4 ;
_boot_copy_loop:
lwzu r14, 4(r12) ;
stwu r14, 4(r13) ;
bdnz _boot_copy_loop ;
/* Synchronize the whole execution context */
addi r12, r11, (_boot_sync - _boot_start) ;
mtspr SRR0, r12 ;
mfmsr r12 ;
mtspr SRR1, r12 ;
rfi ;
_boot_sync:
/* All done, jump into the loaded code */
blrl ;
/* If we ever return, reboot */
b _start ;
.space BOOT_SIZE - 4 - (. - _boot_start), 0xFF
/* Reset entry point */
. = 0x1FC
_start:
bl _boot_start ;
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