//-------------------------------------------------------------------
//	earlymbr.c
//
//	This module reads the hard disk's Master Boot Record during 
//	its initialization procedure.  It uses the kernel functions 
//	'preempt_disable()' and 'preempt_enable()' in order that it
//	can circumvent contention with the kernel's own IDE driver. 
//	(Use 'dmesg' command to display output sent to kernel log.)
//
//	NOTE: Developed and tested with Linux kernel version 2.6.10
//
//	programmer: ALLAN CRUSE
//	written on: 06 MAR 2005
//-------------------------------------------------------------------

#include <linux/module.h>	// for init_module() 
#include <linux/delay.h>	// for ndelay()
#include <linux/preempt.h>	// for preempt_disable()
#include <asm/io.h>		// for inb(), outb()

#define IDE_DATA		0x1F0
#define IDE_ERROR		0x1F1
#define IDE_FEATURES		0x1F1
#define IDE_SECTOR_COUNT	0x1F2
#define IDE_SECTOR_LOW	 	0x1F3
#define IDE_SECTOR_MID		0x1F4
#define IDE_SECTOR_HIGH		0x1F5
#define IDE_DEVICE		0x1F6
#define IDE_STATUS		0x1F7
#define IDE_COMMAND 		0x1F7
#define IDE_DEVICE_CONTROL	0x3F6

char modname[] = "earlymbr";	// for displaying module's name
unsigned short	info[ 256 ];	// for holding the MBR sector

int init_module( void )
{
	int	i, status, timeout;

	printk( "<1>\nInstalling \'%s\' module \n", modname );

	status = inb( IDE_STATUS );
	printk( "1: status=%02X \n", status );
	if ( ( status & 0xC8 ) != 0x40 ) return -EBUSY; 

	preempt_disable();
	
	status = inb( IDE_STATUS );
	if ( ( status & 0xC8 ) == 0x40 )
		{
		outb( 0xE0, IDE_DEVICE );
		ndelay( 400 );
		}

	status = inb( IDE_STATUS );
	printk( "2: status=%02X \n", status );

	if ( ( status & 0xC8 ) == 0x40 ) 
		{
		outb( 0x01, IDE_SECTOR_COUNT );
		outb( 0x00, IDE_SECTOR_LOW );
		outb( 0x00, IDE_SECTOR_MID );
		outb( 0x00, IDE_SECTOR_HIGH );
		outb( 0xE0, IDE_DEVICE );
		outb( 0x20, IDE_COMMAND );
		ndelay( 400 );
		}

	status = inb( IDE_STATUS );
	printk( "3: status=%02X \n", status );

	timeout = 1000000;
	do	{
		status = inb( IDE_STATUS );
		if ( ( status & 0x88 ) == 0x08 ) break;
		}
	while ( --timeout );
	printk( "4: status=%02X \n", status );

	if ( ( status & 0x88 ) == 0x08 )
		{
		int	i;
		for (i = 0; i < 256; i++) info[i] = inw( IDE_DATA );
		}
	ndelay( 400 );
	status = inb( IDE_STATUS );
	printk( "5: status=%02X \n", status );

	preempt_enable();

	printk( "\nPartition-Table and Boot-Signature ");
	for (i = 0; i < 33; i++)
		{
		if ( ( i % 8 ) == 0 ) printk( "\n" );
		printk( "%04X ", info[223+i] );
		}
	printk( "\n\n" );
	return 	0;  // SUCCESS
}


void cleanup_module( void )
{
	printk( "<1>Removing \'%s\' module\n", modname );
}


MODULE_LICENSE("GPL");