LXR syslinux/gpxe/src/arch/i386/interface/pcbios/bios

   1/*
   2 * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public License as
   6 * published by the Free Software Foundation; either version 2 of the
   7 * License, or any later version.
   8 *
   9 * This program is distributed in the hope that it will be useful, but
  10 * WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 * General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write to the Free Software
  16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17 */
  18
  19FILE_LICENCE ( GPL2_OR_LATER );
  20
  21#include <stdint.h>
  22#include <string.h>
  23#include <errno.h>
  24#include <assert.h>
  25#include <gpxe/uaccess.h>
  26#include <gpxe/smbios.h>
  27#include <realmode.h>
  28#include <pnpbios.h>
  29
  30/** @file
  31 *
  32 * System Management BIOS
  33 *
  34 */
  35
  36/**
  37 * Find SMBIOS
  38 *
  39 * @v smbios            SMBIOS entry point descriptor structure to fill in
  40 * @ret rc              Return status code
  41 */
  42static int bios_find_smbios ( struct smbios *smbios ) {
  43        union {
  44                struct smbios_entry entry;
  45                uint8_t bytes[256]; /* 256 is maximum length possible */
  46        } u;
  47        static unsigned int offset = 0;
  48        size_t len;
  49        unsigned int i;
  50        uint8_t sum;
  51
  52        /* Try to find SMBIOS */
  53        for ( ; offset < 0x10000 ; offset += 0x10 ) {
  54
  55                /* Read start of header and verify signature */
  56                copy_from_real ( &u.entry, BIOS_SEG, offset,
  57                                 sizeof ( u.entry ));
  58                if ( u.entry.signature != SMBIOS_SIGNATURE )
  59                        continue;
  60
  61                /* Read whole header and verify checksum */
  62                len = u.entry.len;
  63                copy_from_real ( &u.bytes, BIOS_SEG, offset, len );
  64                for ( i = 0 , sum = 0 ; i < len ; i++ ) {
  65                        sum += u.bytes[i];
  66                }
  67                if ( sum != 0 ) {
  68                        DBG ( "SMBIOS at %04x:%04x has bad checksum %02x\n",
  69                              BIOS_SEG, offset, sum );
  70                        continue;
  71                }
  72
  73                /* Fill result structure */
  74                DBG ( "Found SMBIOS v%d.%d entry point at %04x:%04x\n",
  75                      u.entry.major, u.entry.minor, BIOS_SEG, offset );
  76                smbios->address = phys_to_user ( u.entry.smbios_address );
  77                smbios->len = u.entry.smbios_len;
  78                smbios->count = u.entry.smbios_count;
  79                return 0;
  80        }
  81
  82        DBG ( "No SMBIOS found\n" );
  83        return -ENODEV;
  84}
  85
  86PROVIDE_SMBIOS ( pcbios, find_smbios, bios_find_smbios );
  87