//-------------------------------------------------------------------
//	serialno.c	  (One solution for Midterm II, Question V)
//
//	This module create a pseudo-file that shows the hard disk's
//	serial-number, along with the name of this module's author.
//
//	programmer: ALLAN CRUSE
//	written on: 10 MAR 2005
//-------------------------------------------------------------------

#include <linux/module.h>	// for init_module() 
#include <linux/proc_fs.h>	// for create_proc_info_entry() 
#include <linux/delay.h>	// for ndelay()
#include <asm/uaccess.h>	// for copy_to_user() 
#include <asm/io.h>		// for inb(), outb()

#define IDE_DATA		0x1F0
#define IDE_ERROR		0x1F1
#define IDE_DEVICE		0x1F6
#define IDE_STATUS		0x1F7
#define IDE_COMMAND 		0x1F7

#define CMD_IDENTIFY_DEVICE	0xEC

char modname[] = "serialno";	// for displaying module's name
unsigned short buffer[ 256 ];	// for storing disk information

int my_get_info( char *buf, char **start, off_t off, int count )
{
	int 	read_device_info( void ), i, error, len = 0;

	if ( ( error = read_device_info() ) == 0 )	 
	 	{ // show serial-number: 20 ascii characters at word offset 10 
		char	*cp = (char*)&buffer[10];
		len += sprintf(buf+len, "Hard disk serial number: ");
		for (i = 0; i < 20; i++) len += sprintf( buf+len, "%c", cp[i] );
		len += sprintf(buf+len, "\n");
		}
	else	{ // show error-message and the error-code
		len += sprintf( buf+len, "Error while reading device info. " );
		len += sprintf( buf+len, "Error code = 0x%08X\n", error );	
		} 
	len += sprintf(buf+len, "Module Author: Allan Cruse\n");
	return	len;
}

int init_module( void )
{
	create_proc_info_entry( modname, 0, NULL, my_get_info );
	return	0;  //SUCCESS
}

void cleanup_module( void )
{
	remove_proc_entry( modname, NULL );
}

// This helper-function reads device-information from the master disk

int read_device_info( void )
{
	int	i, status, timeout, error = 0;	
	
	// Hard Disk Device-Selection Protocol
	// wait until BSY==0 (bit 7) and DREQ==0 (bit 3)
	timeout = 1000;
	do	{
		status = inb( IDE_STATUS );
		if ( (status & 0x88 ) == 0x00 ) break;
		}
	while ( --timeout );
	if ( timeout == 0 ) return -EBUSY;

	// select the disk drive 	
	outb( 0xE0, IDE_DEVICE );	// master disk, LBA addressing
	ndelay( 400 );			// delay for 400 nanoseconds

	status = inb( IDE_STATUS );
	if ( (status & 0xC8 ) != 0x40 ) return -EFAULT;

	// ok, drive is now ready for the command	
	outb( CMD_IDENTIFY_DEVICE, IDE_COMMAND );

	ndelay( 400 );			// delay for 400 nanoseconds	
	status = inb( IDE_STATUS );	// was any error info posted?
	if ( (status & 0x81) == 0x01 ) 
		{
		error = inb( IDE_ERROR );
		return	error;
		}

	// wait for the DRQ indicator
	timeout = 1000000;
	do	{
		status = inb( IDE_STATUS );
		if ( (status & 0x88) == 0x08 ) break;
		}
	while ( --timeout );
	if ( timeout == 0 ) return -EFAULT;	

	// transfer data from the controller's sector-buffer
	for (i = 0; i < 256; i++) buffer[i] = inw( IDE_DATA );
	ndelay( 400 );

	// read status register (clears any pending interrupt)
	status = inb( IDE_STATUS );
	return	0;  //SUCCESS			
}

MODULE_LICENSE("GPL");