src/arch/x86/interface/pcbios/int13con.c

/*
 * Copyright (C) 2015 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <ipxe/console.h>
#include <ipxe/disklog.h>
#include <ipxe/init.h>
#include <realmode.h>
#include <int13.h>
#include <config/console.h>

/** @file
 *
 * INT13 disk log console
 *
 */

/* Set default console usage if applicable
 *
 * We accept either CONSOLE_DISKLOG or CONSOLE_INT13.
 */
#if ( defined ( CONSOLE_DISKLOG ) && ! defined ( CONSOLE_INT13 ) )
#define CONSOLE_INT13 CONSOLE_DISKLOG
#endif
#if ! ( defined ( CONSOLE_INT13 ) && CONSOLE_EXPLICIT ( CONSOLE_INT13 ) )
#undef CONSOLE_INT13
#define CONSOLE_INT13 ( CONSOLE_USAGE_ALL & ~CONSOLE_USAGE_LOG )
#endif

/** Disk drive number */
#define INT13CON_DRIVE 0x80

/** Original INT13 vector */
static struct segoff __bss16 ( int13con_vector );
#define int13con_vector __use_data16 ( int13con_vector )

/** Sector buffer */
static uint8_t __bss16_array ( int13con_buffer, [INT13_BLKSIZE] );
#define int13con_buffer __use_data16 ( int13con_buffer )

/** Disk address packet */
static struct int13_disk_address __bss16 ( int13con_address );
#define int13con_address __use_data16 ( int13con_address )

/** Disk log */
static struct disklog int13con_disklog;

struct console_driver int13con __console_driver;

/**
 * Read/write disk sector
 *
 * @v op		Operation
 * @v lba		Logical block address
 * @ret rc		Return status code
 */
static int int13con_rw ( unsigned int op, uint64_t lba ) {
	uint8_t error;

	/* Construct disk address packet */
	int13con_address.bufsize = sizeof ( int13con_address );
	int13con_address.count = 1;
	int13con_address.buffer.segment = rm_ds;
	int13con_address.buffer.offset = __from_data16 ( int13con_buffer );
	int13con_address.lba = lba;

	/* Emulate INT13 via original vector.  We do this since iPXE
	 * (or another subsequent bootloader) may hook INT13 and remap
	 * drive numbers.
	 */
	__asm__ ( REAL_CODE ( "pushfw\n\t"
			      "cli\n\t"
			      "lcall *int13con_vector\n\t" )
		  : "=a" ( error )
		  : "0" ( op << 8 ), "d" ( INT13CON_DRIVE ),
		    "S" ( __from_data16 ( &int13con_address ) ) );
	if ( error ) {
		DBG ( "INT13CON operation %04x failed: %02x\n",
		      op, error );
		return -EIO;
	}

	return 0;
}

/**
 * Write current logical block
 *
 * @ret rc		Return status code
 */
static int int13con_write ( void ) {

	/* Write block */
	return int13con_rw ( INT13_EXTENDED_WRITE, int13con_disklog.lba );
}

/** INT13 disk log operations */
static struct disklog_operations int13con_op = {
	.write = int13con_write,
};

/**
 * Write character to console
 *
 * @v character		Character
 */
static void int13con_putchar ( int character ) {

	/* Write character */
	disklog_putchar ( &int13con_disklog, character );
}

/**
 * Find log partition
 *
 * @ret rc		Return status code
 */
static int int13con_find ( void ) {
	struct master_boot_record *mbr =
		( ( struct master_boot_record * ) int13con_buffer );
	struct partition_table_entry part[4];
	unsigned int i;
	int rc;

	/* Read MBR */
	if ( ( rc = int13con_rw ( INT13_EXTENDED_READ, 0 ) ) != 0 ) {
		DBG ( "INT13CON could not read MBR: %s\n", strerror ( rc ) );
		return rc;
	}

	/* Check MBR magic */
	if ( mbr->magic != INT13_MBR_MAGIC ) {
		DBG ( "INT13CON incorrect MBR magic\n" );
		DBG2_HDA ( 0, mbr, sizeof ( *mbr ) );
		return -EINVAL;
	}

	/* Look for magic partition */
	memcpy ( part, mbr->partitions, sizeof ( part ) );
	for ( i = 0 ; i < ( sizeof ( part ) / sizeof ( part[0] ) ) ; i++ ) {

		/* Skip partitions of the wrong type */
		if ( part[i].type != DISKLOG_PARTITION_TYPE )
			continue;

		/* Read partition header */
		if ( ( rc = int13con_rw ( INT13_EXTENDED_READ,
					  part[i].start ) ) != 0 ) {
			DBG ( "INT13CON partition %d could not read header: "
			      "%s\n", ( i + 1 ), strerror ( rc ) );
			continue;
		}

		/* Initialise disk log console */
		disklog_init ( &int13con_disklog, &int13con_op, &int13con,
			       int13con_buffer, INT13_BLKSIZE, part[i].start,
			       ( part[i].start + part[i].length - 1 ) );

		/* Open disk log console */
		if ( ( rc = disklog_open ( &int13con_disklog ) ) != 0 ) {
			DBG ( "INT13CON partition %d could not initialise: "
			      "%s\n", ( i + 1 ), strerror ( rc ) );
			continue;
		}

		/* Found log partition */
		DBG ( "INT13CON partition %d at [%08llx,%08llx)\n", ( i + 1 ),
		      ( ( unsigned long long ) int13con_disklog.lba ),
		      ( ( unsigned long long ) int13con_disklog.max_lba ) );

		return 0;
	}

	DBG ( "INT13CON found no log partition\n" );
	return -ENOENT;
}

/**
 * Initialise INT13 console
 *
 */
static void int13con_init ( void ) {
	uint8_t error;
	uint16_t check;
	unsigned int discard_c;
	unsigned int discard_d;
	int rc;

	/* Check for INT13 extensions */
	__asm__ __volatile__ ( REAL_CODE ( "int $0x13\n\t"
					   "setc %%al\n\t" )
			       : "=a" ( error ), "=b" ( check ),
				 "=c" ( discard_c ), "=d" ( discard_d )
			       : "0" ( INT13_EXTENSION_CHECK << 8 ),
				 "1" ( 0x55aa ), "3" ( INT13CON_DRIVE ) );
	if ( error || ( check != 0xaa55 ) ) {
		DBG ( "INT13CON missing extensions (%02x,%04x)\n",
		      error, check );
		return;
	}

	/* Store original INT13 vector */
	copy_from_real ( &int13con_vector, 0, ( 0x13 * 4 ),
			 sizeof ( int13con_vector ) );
	DBG ( "INT13CON using original INT13 vector %04x:%04x\n",
	      int13con_vector.segment, int13con_vector.offset );

	/* Locate log partition */
	if ( ( rc = int13con_find() ) != 0)
		return;

	/* Enable console */
	int13con.disabled = 0;
}

/**
 * INT13 console initialisation function
 */
struct init_fn int13con_init_fn __init_fn ( INIT_CONSOLE ) = {
	.name = "int13con",
	.initialise = int13con_init,
};

/** INT13 console driver */
struct console_driver int13con __console_driver = {
	.putchar = int13con_putchar,
	.disabled = CONSOLE_DISABLED,
	.usage = CONSOLE_INT13,
};

/* Request a log partition from genfsimg */
__asm__ ( ".globl ipxe_oem_info_disklog\n\t"
	  ".equ ipxe_oem_info_disklog, 0x0001\n\t" );