Colony » Colony Scout » Colony Scout OS

/*-

 * Copyright (c) 2005-2007, Kohsuke Ohtani

 * 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. Neither the name of the author nor the names of any co-contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.

 */

/*

 * head.S - low level platform support

 */

#include <conf/config.h>

#include <machine/memory.h>

#include <machine/syspage.h>

#define SCREEN_80x25 1

/* #define SCREEN_80x50 1 */

#define SEL_CODE32	0x10

#define SEL_DATA32	0x18

#define ENTRY(x) .global x; .align; x##:

	.text

	.code16

/*

 * boot_entry - Entry point for prex boot loader.

 *

 * We assume boot sector copied us at 0x30000.

 */

ENTRY(boot_entry)

	cld

	cli				/* Disable all interrupts */

	/*

	 * Relocate boot loader to 0x4000.

	 */

	movw	%cs, %ax

	movw	%ax, %ds

	xorw	%si, %si		/* Source address cs:0 */

	movw	%si, %es

	movw	$0x4000, %di		/* Destination */

	movw	$0x800, %cx		/* size 8K */

	rep	movsl

	ljmp	$0x0000, $(reset_cs)

reset_cs:

	movw	%cs, %ax		/* Reset segment registers */

	movw	%ax, %ds

	xorw	%ax, %ax		/* Reset stack */

	movw	%ax, %ss

	movw	$(BOOTSTKTOP - KERNBASE), %sp

	/*

	 * Do 16-bit BIOS call here.

	 */

	call	setup_screen

	call	get_memsize

	/*

	 * Switch to 32-bit protected mode.

	 */

	call	enable_a20		/* Enable A20 line */

	lgdt	gdt_desc		/* Load GDT */

	movl	%cr0, %eax		/* Set PE bit in CR0 */

	orl	$0x1, %eax

	movl	%eax, %cr0

	.byte	0x66			/* 32-bit long jump to reset CS */

	.byte	0xea

	.long	go_prot

	.word	SEL_CODE32

	.code32

.align 4

go_prot:

	movw	$(SEL_DATA32), %ax	/* Reset all segments */

	movw	%ax, %ds

	movw	%ax, %es

	movw	%ax, %ss

	movw	%ax, %fs

	movw	%ax, %gs

	/*

	 * Relocate OS image.

	 */

	movl	$(CONFIG_BOOTIMG_BASE - KERNBASE), %edi	/* Destination */

	movl	$0x32000, %esi		/* Source address: 0x32000 */

	movl	$0x1B800, %ecx		/* size 0x6e000 */

	rep	movsl

	jmp	main			/* Jump to main routine in C */

/*

 * get_memsize - Get memory size

 */

	.code16

get_memsize:

	xorl	%eax, %eax

	int	$0x12			/* Get conventional memory size */

	movl	%eax, lo_mem		/* ax = K bytes */

	mov	$0x88, %ah

	int	$0x15

	andb	$0xfc, %al		/* Adjust to page boundary */

	movl	%eax, hi_mem		/* ax = K bytes at 100000h */

	ret

/*

 * enable_a20 - Enable A20

 */

	.code16

enable_a20:

	call	empty_8042

	movb	$0xd1, %al

	outb	%al, $0x64

	call	empty_8042

	movb	$0xdf, %al

	outb	%al, $0x60

	call	empty_8042

	call	wait_a20

	ret

/*

 * empty_8042 - Empty 8042

 */

empty_8042:

	inb	$0x64, %al

	testb	$0x01, %al

	jz	no_output

	inb	$0x60, %al

	jmp	empty_8042

no_output:

	testb	$0x02, %al

	jnz	empty_8042

	ret

/*

 * wait_a20 - Wait A20 ready

 */

wait_a20:

        xorw    %ax, %ax

        movw    %ax, %fs

        movw    $0xffff, %ax

        movw    %ax, %gs

        movw    %fs:(0x0), %ax

        cmp     %gs:(16), %ax

        jne     a20_ready

        movw    %dx, %ax

        notw    %ax

        movw    %ax, %fs:(0x0)

        cmp     %gs:(16), %ax

        mov     %fs:(0), %dx

        jne     a20_ready

        jmp	wait_a20

a20_ready:

        ret

/*

 * Setup screen

 */

setup_screen:

	pushaw

	pushw	%es

	pushw	%ds

	pushw	%bp

	movb	$0x2e, %al		/* print '.' for verify */

	movb	$0x0e, %ah

	movw	$0x07, %bx

	int	$0x10

	movw	$0x3, %ax		/* Use mode-3 */

	int	$0x10

	movw	$0x1202, %ax		/* 400 scan lines */

	movb	$0x30, %bl

	int	$0x10

#if SCREEN_80x50

	movw	$0x1112, %ax		/* Load 8x8 character set */

	movb	$0x0, %bl

	int	$0x10

	movw	$0x1201, %ax		/* Turn off cursor emulation */

	movb	$0x34, %bl

	int	$0x10

	movb	$0x01, %ah		/* Set cursor type */

	movw	$0x0607, %cx

	int	$0x10

#endif

	popw	%bp

	popw	%ds

	popw	%es

	popaw

	ret

	.code32

ENTRY(outb)

	movl	4(%esp), %edx

	movl	8(%esp), %eax

	outb	%al, %dx

	ret

ENTRY(inb)

	movl	4(%esp), %edx

	xorl	%eax, %eax

	inb	%dx, %al

	ret

/*

 * Data

 */

.align 16

gdt:

	.word 0x0,0x0,0x0,0x0		/* 0x00 - Null descritor */

	.word 0x0,0x0,0x0,0x0		/* 0x08 - Null descritor */

	.word 0xffff,0x0,0x9a00,0xcf	/* 0x10 - 32 bit code segment */

	.word 0xffff,0x0,0x9200,0xcf	/* 0x18 - 32 bit data segment */

	.word 0xffff,0x0,0x9a00,0x0	/* 0x20 - 16 bit code segment */

	.word 0xffff,0x0,0x9200,0x0	/* 0x28 - 16 bit data segment */

gdt_desc:

	.word	0x2F			/* limit */

	.long	gdt			/* address */

	.word	0x0			/* alignment */

idt_desc:

	.word	0x0

	.long	0x0

e820_buf:

	.space	20

	.align 16

	.global lo_mem, hi_mem

lo_mem:

	.long	0x0

hi_mem:

	.long	0x0

/*

 * Pad data

 */

	.section .tail,"a"

dummy:

	.byte	0xff