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#
# Copyright (C) 2006 Martin Decky
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

#include "asm.h"
#include "regname.h"

.text

.global halt
.global memcpy
.global jump_to_kernel

halt:
    b halt

memcpy:
    srwi. r7, r5, 3
    addi r6, r3, -4
    addi r4, r4, -4
    beq 2f
    
    andi. r0, r6, 3
    mtctr r7
    bne 5f
    
    1:
    
    lwz r7, 4(r4)
    lwzu r8, 8(r4)
    stw r7, 4(r6)
    stwu r8, 8(r6)
    bdnz 1b
    
    andi. r5, r5, 7
    
    2:
    
    cmplwi 0, r5, 4
    blt 3f
    
    lwzu r0, 4(r4)
    addi r5, r5, -4
    stwu r0, 4(r6)
    
    3:
    
    cmpwi 0, r5, 0
    beqlr
    mtctr r5
    addi r4, r4, 3
    addi r6, r6, 3
    
    4:
    
    lbzu r0, 1(r4)
    stbu r0, 1(r6)
    bdnz 4b
    blr
    
    5:
    
    subfic r0, r0, 4
    mtctr r0
    
    6:
    
    lbz r7, 4(r4)
    addi r4, r4, 1
    stb r7, 4(r6)
    addi r6, r6, 1
    bdnz 6b
    subf r5, r0, r5
    rlwinm. r7, r5, 32-3, 3, 31
    beq 2b
    mtctr r7
    b 1b


jump_to_kernel:
    
    # r3 = bootinfo (pa)
    # r4 = bootinfo_size
    # r5 = trans (pa)
    # r6 = kernel size
    # r7 = framebuffer (pa)
    # r8 = real_mode (pa)
    
    # disable interrupts
    
    mfmsr r31
    rlwinm r31, r31, 0, 17, 15
    mtmsr r31
    
    # set real_mode meeting point address
    
    mtspr srr0, r8
    
    # jumps to real_mode
    
    mfmsr r31
    lis r30, ~0@h
    ori r30, r30, ~(msr_ir | msr_dr)@l
    and r31, r31, r30
    mtspr srr1, r31
    
    sync
    isync
    rfi

.section REALMODE, "ax"
.align PAGE_WIDTH
.global real_mode

real_mode:
    
    # copy kernel to proper location
    #
    # r5 = trans (pa)
    # r6 = kernel size
    # r7 = framebuffer (pa)
    
    li r31, PAGE_SIZE >> 2
    li r30, 0
    
    page_copy:
        
        cmpwi r6, 0
        beq copy_end
        
        # copy page
        
        mtctr r31
        lwz r29, 0(r5)
        
        copy_loop:
            
            lwz r28, 0(r29)
            stw r28, 0(r30)
            
            addi r29, r29, 4
            addi r30, r30, 4
            subi r6, r6, 4
            
            cmpwi r6, 0
            beq copy_end
            
            bdnz copy_loop
        
        addi r5, r5, 4
        b page_copy
    
    copy_end:
    
    # initially fill segment registers

    li r31, 16
    mtctr r31
    li r31, 0
    li r30, 0x2000

    seg_fill:
    
        mtsrin r30, r31
        addi r30, r30, 0x111
        addis r31, r31, 0x1000    # move to next SR
        
        bdnz seg_fill
    
    # invalidate block address translation registers
    
    mtspr ibat0u, r30
    mtspr ibat0l, r30
    
    mtspr ibat1u, r30
    mtspr ibat1l, r30
    
    mtspr ibat2u, r30
    mtspr ibat2l, r30
    
    mtspr ibat3u, r30
    mtspr ibat3l, r30
    
    mtspr dbat0u, r30
    mtspr dbat0l, r30
    
    mtspr dbat1u, r30
    mtspr dbat1l, r30
    
    mtspr dbat2u, r30
    mtspr dbat2l, r30
    
    mtspr dbat3u, r30
    mtspr dbat3l, r30
    
    # create identity mapping
    
    # FIXME: map exactly the size of RAM
    
    lis r31, 0x8000
    ori r31, r31, 0x0ffe
    
    lis r30, 0x0000
    ori r30, r30, 0x0002
    
    mtspr ibat0u, r31
    mtspr ibat0l, r30
    
    mtspr dbat0u, r31
    mtspr dbat0l, r30
    
    # FIXME: temporal framebuffer mapping
    
    lis r31, 0xf000
    ori r31, r31, 0x0ffe
    
    mr r30, r7
    ori r30, r30, 0x0002
    
    mtspr dbat1u, r31
    mtspr dbat1l, r30
    
    tlbia
    
    # start the kernel
    #
    # r3 = bootinfo (pa)
    
    lis r31, KERNEL_START_ADDR@ha
    addi r31, r31, KERNEL_START_ADDR@l
    
    mtspr srr0, r31
    
    mfmsr r31
    ori r31, r31, (msr_ir | msr_dr)@l
    mtspr srr1, r31
    
    sync
    isync
    rfi

.align PAGE_WIDTH
.global trans
trans:
    .space (TRANS_SIZE * TRANS_ITEM_SIZE)