src/arch/i386/interface/pcbios/bios_smbios.c

   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
  19 FILE_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  */
  42 static 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
  86 PROVIDE_SMBIOS ( pcbios, find_smbios, bios_find_smbios );