source: bootcd/isolinux/syslinux-6.03/gpxe/src/interface/efi/efi_init.c

/*
 * Copyright (C) 2008 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 <string.h>
#include <gpxe/efi/efi.h>
#include <gpxe/uuid.h>

/** Image handle passed to entry point */
EFI_HANDLE efi_image_handle;

/** System table passed to entry point */
EFI_SYSTEM_TABLE *efi_systab;

/**
 * Look up EFI configuration table
 *
 * @v guid              Configuration table GUID
 * @ret table           Configuration table, or NULL
 */
static void * efi_find_table ( EFI_GUID *guid ) {
        unsigned int i;

        for ( i = 0 ; i < efi_systab->NumberOfTableEntries ; i++ ) {
                if ( memcmp ( &efi_systab->ConfigurationTable[i].VendorGuid,
                              guid, sizeof ( *guid ) ) == 0 )
                        return efi_systab->ConfigurationTable[i].VendorTable;
        }

        return NULL;
}

/**
 * Initialise EFI environment
 *
 * @v image_handle      Image handle
 * @v systab            System table
 * @ret efirc           EFI return status code
 */
EFI_STATUS efi_init ( EFI_HANDLE image_handle,
                      EFI_SYSTEM_TABLE *systab ) {
        EFI_BOOT_SERVICES *bs;
        struct efi_protocol *prot;
        struct efi_config_table *tab;
        EFI_STATUS efirc;

        /* Store image handle and system table pointer for future use */
        efi_image_handle = image_handle;
        efi_systab = systab;

        /* Sanity checks */
        if ( ! systab )
                return EFI_NOT_AVAILABLE_YET;
        if ( ! systab->ConOut )
                return EFI_NOT_AVAILABLE_YET;
        if ( ! systab->BootServices ) {
                DBGC ( systab, "EFI provided no BootServices entry point\n" );
                return EFI_NOT_AVAILABLE_YET;
        }
        if ( ! systab->RuntimeServices ) {
                DBGC ( systab, "EFI provided no RuntimeServices entry "
                       "point\n" );
                return EFI_NOT_AVAILABLE_YET;
        }
        DBGC ( systab, "EFI handle %p systab %p\n", image_handle, systab );

        /* Look up used protocols */
        bs = systab->BootServices;
        for_each_table_entry ( prot, EFI_PROTOCOLS ) {
                if ( ( efirc = bs->LocateProtocol ( &prot->u.guid, NULL,
                                                    prot->protocol ) ) == 0 ) {
                        DBGC ( systab, "EFI protocol %s is at %p\n",
                               uuid_ntoa ( &prot->u.uuid ), *(prot->protocol));
                } else {
                        DBGC ( systab, "EFI does not provide protocol %s\n",
                               uuid_ntoa ( &prot->u.uuid ) );
                        /* All protocols are required */
                        return efirc;
                }
        }

        /* Look up used configuration tables */
        for_each_table_entry ( tab, EFI_CONFIG_TABLES ) {
                if ( ( *(tab->table) = efi_find_table ( &tab->u.guid ) ) ) {
                        DBGC ( systab, "EFI configuration table %s is at %p\n",
                               uuid_ntoa ( &tab->u.uuid ), *(tab->table) );
                } else {
                        DBGC ( systab, "EFI does not provide configuration "
                               "table %s\n", uuid_ntoa ( &tab->u.uuid ) );
                        if ( tab->required )
                                return EFI_NOT_AVAILABLE_YET;
                }
        }

        return 0;
}