xref: /src/sys/arch/amiga/stand/bootblock/boot/startit.s

/*	$NetBSD: startit.s,v 1.4 1998/11/06 20:08:20 is 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Michael L. Hitch.
 * 4. 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.
 *
 *
 * From: $NetBSD: startit.s,v 1.4 1998/11/06 20:08:20 is Exp $
 */

	.set	ABSEXECBASE,4

	.text

	.globl	_startit
	.globl	_startit_end

_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@(_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

| ---- switch off cache ----
	btst	#3,d5
	jeq	L3
	.word	0xf4f8
L3:	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

| ---- 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@(_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
	rts

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

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

	rts				| jmps to relocated ckend

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

	lea	pc@(ckend:w),a1
	movl	a3,sp@-
	pea	pc@(_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

	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

_startit_end: