/*      $NetBSD: romboot.S,v 1.8 2005/12/11 12:17:34 christos Exp $     */

/*-
 * Copyright (c) 2001, 2002, 2003 Takao Shinohara.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * 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.
 */

/*
 * simple boot loader for ROM
 *
 * supported platform: LASER5 L-Router(L-Board)
 */     
        
#define zero    $0
#define AT      $at
#define v0      $2
#define v1      $3
#define a0      $4
#define a1      $5
#define a2      $6
#define a3      $7
#define t0      $8
#define t1      $9
#define t2      $10
#define t3      $11
#define t4      $12
#define t5      $13
#define t6      $14
#define t7      $15
#define s0      $16
#define s1      $17
#define s2      $18
#define s3      $19
#define s4      $20
#define s5      $21
#define s6      $22
#define s7      $23
#define t8      $24
#define t9      $25
#define k0      $26
#define k1      $27
#define gp      $28
#define sp      $29
#define s8      $30
#define ra      $31

#define MIPS_KSEG0_START        0x80000000
#define MIPS_KSEG1_START        0xa0000000
#define KSEG1_KSEG0_DIFF        (MIPS_KSEG1_START - MIPS_KSEG0_START)
#define KERNEL_LOADADDR         0x80001000
#define MAX_KERNEL_SIZE         (1024*1024*6)   # 6MB
#define MAX_DCACHE_SIZE         (1024*32)       # 32KB

        .text
        .set    noreorder
        .globl  _start
_start:
        bal     1f                      # ra = ROM address + 8
        nop
1:      subu    a0, ra, 8               # a0 = ROM address(kseg1)
        subu    a0, KSEG1_KSEG0_DIFF    # convert to kseg0 address
        move    s0, a0                  # keep it in s0 
        la      t0, _etext
        la      t1, _ftext
        subu    t0, t1                  # t0 = size of boot loader
        addu    a0, t0                  # a0 = kernel address in ROM
        li      a1, KERNEL_LOADADDR
        li      t2, MAX_KERNEL_SIZE     # max kernel size = 6MB - boot
        subu    t2, t0
        addu    t2, a1                  # kernel end address
        la      t9, 2f
        addu    t9, s0
        jr      t9                      # jump to cached address
        nop
2:
        lw      v0, 0(a0)
        sw      v0, 0(a1)
        addu    a0, 4
        bltu    a1, t2, 2b
        addu    a1, 4                   # BDSLOT

        /* purge data cache */
        li      v0, MAX_DCACHE_SIZE
3:      lw      zero, 0(a1)
        addu    a1, 4
        bnez    v0, 3b
        subu    v0, 4                   # BDSLOT

        li      sp, KERNEL_LOADADDR     # initialize stack pointer
        li      a0, 1                   # argc = 1
        addu    a1, sp, -16             # argv
        la      t0, argv0
        addu    t0, s0
        sw      t0, 0(a1)               # argv[0] = "netbsd"
        sw      zero, 4(a1)             # argv[1] = NULL
        la      a2, bootinfo
        addu    a2, s0
        move    a3, zero
        li      t9, KERNEL_LOADADDR
        jr      t9
        nop

argv0:  .asciiz "netbsd"

bootinfo:
        .word   34              # len
        .word   0x13536135      # magic
        .word   0               # fb_addr
        .word   0, 0            # fb_line_bytes, fb_width, fb_height, fb_type
        .word   2               # BI_CNUSE_SERIAL
        .word   0x04104500      # VR4122
        .word   0x03810200      # LASER5 L-BOARD
/*
 * kernel binary image begins here.
 */