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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 ;