/*      $NetBSD: startit.s,v 1.9 2009/11/15 20:38:36 snj Exp $  */

/*
 * Copyright (c) 1996 Ignatios Souvatzis
 * Copyright (c) 1994 Michael L. Hitch
 * All rights reserved.
 *
 * 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.
 *
 *
 * From: $NetBSD: startit.s,v 1.9 2009/11/15 20:38:36 snj Exp $
 */
#include <machine/asm.h>

        .set    ABSEXECBASE,4

        .text

ENTRY_NOPROFILE(startit)
#if TESTONAMIGA
        movew   #0x999,0xdff180         | gray
#endif
#if TESTONDRACO
        moveb   #0,0x200003c8
        moveb   #31,0x200003c9
        moveb   #31,0x200003c9
        moveb   #31,0x200003c9
#endif
        movel   %sp,%a3
        movel   4:w,%a6
        lea     %pc@(start_super:w),%a5
        jmp     %a6@(-0x1e)             | supervisor-call

start_super:
#if TESTONAMIGA
        movew   #0x900,0xdff180         | dark red
#endif
        movew   #0x2700,%sr

        | the BSD kernel wants values into the following registers:
        | %a0:  fastmem-start
        | %d0:  fastmem-size
        | %d1:  chipmem-size
        | %d3:  Amiga specific flags
        | %d4:  E clock frequency
        | %d5:  AttnFlags (cpuid)
        | %d6:  boot partition offset
        | %d7:  boothowto
        | %a4:  esym location
        | %a2:  Inhibit sync flags
        | All other registers zeroed for possible future requirements.

        lea     %pc@(_C_LABEL(startit):w),%sp   | make sure we have a good stack ***

        movel   %a3@(4),%a1             | loaded kernel
        movel   %a3@(8),%d2             | length of loaded kernel
|       movel   %a3@(12),%sp            | entry point in stack pointer
        movel   %a3@(12),%a6            | entry point           ***
        movel   %a3@(16),%a0            | fastmem-start
        movel   %a3@(20),%d0            | fastmem-size
        movel   %a3@(24),%d1            | chipmem-size
        movel   %a3@(28),%d7            | boothowto
        movel   %a3@(32),%a4            | esym
        movel   %a3@(36),%d5            | cpuid
        movel   %a3@(40),%d4            | E clock frequency
        movel   %a3@(44),%d3            | Amiga flags
        movel   %a3@(48),%a2            | Inhibit sync flags
        movel   %a3@(52),%d6            | boot partition offset

        cmpb    #0x7D,%a3@(36)          | is it DraCo?
        movel   %a3@(56),%a3            | Load to fastmem flag
        jeq     nott                    | yes, switch off MMU later

                                        | no, it is an Amiga:

#if TESTONAMIGA
        movew   #0xf00,0xdff180         |red
#endif
#if TESTONDRACO
        moveb   #0,0x200003c8
        moveb   #63,0x200003c9
        moveb   #0,0x200003c9
        moveb   #0,0x200003c9
#endif

        movew   #(1<<9),0xdff096        | disable DMA on Amigas.

| ------ mmu off start -----

        btst    #3,%d5                  | AFB_68040,SysBase->AttnFlags
        jeq     not040

| Turn off 68040/060 MMU

        subl    %a5,%a5
        .word 0x4e7b,0xd003             | movec %a5,tc
        .word 0x4e7b,0xd806             | movec %a5,urp
        .word 0x4e7b,0xd807             | movec %a5,srp
        .word 0x4e7b,0xd004             | movec %a5,itt0
        .word 0x4e7b,0xd005             | movec %a5,itt1
        .word 0x4e7b,0xd006             | movec %a5,dtt0
        .word 0x4e7b,0xd007             | movec %a5,dtt1
        jra     nott

not040:
        lea     %pc@(zero:w),%a5
        pmove   %a5@,%tc                | Turn off MMU
        lea     %pc@(nullrp:w),%a5
        pmove   %a5@,%crp               | Turn off MMU some more
        pmove   %a5@,%srp               | Really, really, turn off MMU

| Turn off 68030 TT registers

        btst    #2,%d5                  | AFB_68030,SysBase->AttnFlags
        jeq     nott                    | Skip TT registers if not 68030
        lea     %pc@(zero:w),%a5
        .word 0xf015,0x0800             | pmove %a5@,tt0 (gas only knows about 68851 ops..)
        .word 0xf015,0x0c00             | pmove %a5@,tt1 (gas only knows about 68851 ops..)

nott:
| ---- mmu off end ----
#if TESTONAMIGA
        movew   #0xf60,0xdff180         | orange
#endif
#if TESTONDRACO
        moveb   #0,0x200003c8
        moveb   #63,0x200003c9
        moveb   #24,0x200003c9
        moveb   #0,0x200003c9
#endif


| ---- copy kernel start ----

| removed Z flag
|       tstl    %a3                     | Can we load to fastmem?
|       jeq     L0                      | No, leave destination at 0
        movl    %a0,%a3                 | Move to start of fastmem chunk
        addl    %a0,%a6                 | relocate kernel entry point

        addl    #3,%d2
        andl    #0xfffffffc,%d2         | round up.

        | determine if the kernel need be copied upwards or downwards

        cmpl    %a1,%a3                 | %a3-a1
        bcs     above                   | source is above

        movl    %a0,%sp
        addl    %d0,%sp                 | move the stack to the end of segment

        | copy from below upwards requires copying from end to start.

        addl    %d2,%a3                 | one long word past
        addl    %d2,%a1                 | one long word past

        subl    #4,%sp                  | alloc space
        movl    %a1,%sp@-                       | save source
        movl    %a3,%sp@-                       | save destination

        | copy copier to end of segment

        movl    %sp,%a3
        subl    #256,%a3                        | end of segment save our stack

        lea     %pc@(_C_LABEL(startit_end):w),%a1
        movl    %a0,%sp@-                       | save segment start
        lea     %pc@(below:w),%a0

L0:     movw    %a1@-,%a3@-
        cmpl    %a0,%a1
        bne     L0
        movl    %sp@,%a0                        | restore segment start
        movl    %a3,%sp@                        | address of relocated below
        addl    #(ckend - below),%a3
        movl    %a3,%sp@(12)            | address of ckend for later
| ---- switch off cache ----
        bra     Lchoff                  | and to relocated below


below:  movl    %sp@+,%a3                       | recover destination
        movl    %sp@+,%a1                       | recover source

L1:     movl    %a1@-,%a3@-             | copy kernel
        subl    #4,%d2
        bne     L1

| ---- switch off cache ----
        bra     Lchoff                  | and to relocated ckend

above:  movl    %a1@+,%a3@+
        subl    #4,%d2
        bne     above

        lea     %pc@(ckend:w),%a1
        movl    %a3,%sp@-
        pea     %pc@(_C_LABEL(startit_end):w)
L2:
        movl    %a1@+,%a3@+
        cmpl    %sp@,%a1
        bcs     L2
        addql   #4,%sp

#if TESTONAMIGA
        movew   #0xFF0,0xdff180         | yellow
#endif
#if TESTONDRACO
        moveb   #0,0x200003c8
        moveb   #63,0x200003c9
        moveb   #63,0x200003c9
        moveb   #0,0x200003c9
#endif

| ---- switch off cache ----
Lchoff: btst    #3,%d5
        jeq     L3c
        .word   0xf4f8
L3c:    movl    %d2,%sp@-                       | save %d2
        movql   #0,%d2                  | switch off cache to ensure we use
        movec   %d2,%cacr                       | valid kernel data
        movl    %sp@+,%d2                       | restore %d2
        rts

| ---- copy kernel end ----

ckend:
#if TESTONAMIGA
        movew   #0x0ff,0xdff180         | petrol
#endif
#if TESTONDRACO
        moveb   #0,0x200003c8
        moveb   #0,0x200003c9
        moveb   #63,0x200003c9
        moveb   #63,0x200003c9
#endif

        movl    %d5,%d2
        roll    #8,%d2
        cmpb    #0x7D,%d2
        jne     noDraCo

| DraCo: switch off MMU now:

        subl    %a5,%a5
        .word 0x4e7b,0xd003             | movec %a5,tc
        .word 0x4e7b,0xd806             | movec %a5,urp
        .word 0x4e7b,0xd807             | movec %a5,srp
        .word 0x4e7b,0xd004             | movec %a5,itt0
        .word 0x4e7b,0xd005             | movec %a5,itt1
        .word 0x4e7b,0xd006             | movec %a5,dtt0
        .word 0x4e7b,0xd007             | movec %a5,dtt1
        
noDraCo:
        moveq   #0,%d2                  | zero out unused registers
        movel   %d2,%a1                 | (might make future compatibility
        movel   %d2,%a3                 |  would have known contents)
        movel   %d2,%a5
        movel   %a6,%sp                 | entry point into stack pointer
        movel   %d2,%a6

#if TESTONAMIGA
        movew   #0x0F0,0xdff180         | green
#endif
#if TESTONDRACO
        moveb   #0,0x200003c8
        moveb   #0,0x200003c9
        moveb   #63,0x200003c9
        moveb   #0,0x200003c9
#endif

        jmp     %sp@                    | jump to kernel entry point


| A do-nothing MMU root pointer (includes the following long as well)

nullrp: .long   0x7fff0001
zero:   .long   0

ENTRY_NOPROFILE(startit_end)