text: /*
   * Copyright (C) 2007 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  FILE_LICENCE ( GPL2_OR_LATER );
  
  #include <stdint.h>
  #include <string.h>
  #include <errno.h>
  #include <assert.h>
  #include <ipxe/uaccess.h>
  #include <ipxe/smbios.h>
  #include <realmode.h>
  #include <pnpbios.h>
  
  /** @file
   *
   * System Management BIOS
   *
   */
  
  /**
   * Find SMBIOS
   *
   * @v smbios		SMBIOS entry point descriptor structure to fill in
   * @ret rc		Return status code
   */
  static int bios_find_smbios ( struct smbios *smbios ) {
  	union {
  		struct smbios_entry entry;
  		uint8_t bytes[256]; /* 256 is maximum length possible */
  	} u;
  	static unsigned int offset = 0;
  	size_t len;
  	unsigned int i;
  	uint8_t sum;
  
  	/* Try to find SMBIOS */
  	for ( ; offset < 0x10000 ; offset += 0x10 ) {
  
  		/* Read start of header and verify signature */
  		copy_from_real ( &u.entry, BIOS_SEG, offset,
  				 sizeof ( u.entry ));
  		if ( u.entry.signature != SMBIOS_SIGNATURE )
  			continue;
  
  		/* Read whole header and verify checksum */
  		len = u.entry.len;
  		copy_from_real ( &u.bytes, BIOS_SEG, offset, len );
  		for ( i = 0 , sum = 0 ; i < len ; i++ ) {
  			sum += u.bytes[i];
  		}
  		if ( sum != 0 ) {
  			DBG ( "SMBIOS at %04x:%04x has bad checksum %02x\n",
  			      BIOS_SEG, offset, sum );
  			continue;
  		}
  
  		/* Fill result structure */
  		DBG ( "Found SMBIOS v%d.%d entry point at %04x:%04x\n",
  		      u.entry.major, u.entry.minor, BIOS_SEG, offset );
  		smbios->address = phys_to_user ( u.entry.smbios_address );
  		smbios->len = u.entry.smbios_len;
  		smbios->count = u.entry.smbios_count;
  		return 0;
  	}
  
  	DBG ( "No SMBIOS found\n" );
  	return -ENODEV;
  }
  
  PROVIDE_SMBIOS ( pcbios, find_smbios, bios_find_smbios );
  