diff options
Diffstat (limited to 'src/VBox/Devices/PC/BIOS/vds.c')
| -rw-r--r-- | src/VBox/Devices/PC/BIOS/vds.c | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/src/VBox/Devices/PC/BIOS/vds.c b/src/VBox/Devices/PC/BIOS/vds.c new file mode 100644 index 00000000..706144a4 --- /dev/null +++ b/src/VBox/Devices/PC/BIOS/vds.c @@ -0,0 +1,128 @@ +/* $Id: vds.c $ */ +/** @file + * Utility routines for calling the Virtual DMA Services. + */ + +/* + * Copyright (C) 2011-2023 Oracle and/or its affiliates. + * + * This file is part of VirtualBox base platform packages, as + * available from https://www.virtualbox.org. + * + * 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, in version 3 of the + * License. + * + * 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, see <https://www.gnu.org/licenses>. + * + * SPDX-License-Identifier: GPL-3.0-only + */ + + +#include <stdint.h> +#include "biosint.h" +#include "vds.h" + +typedef struct { + uint8_t major; /* VDS spec major version number. */ + uint8_t minor; /* VDS spec minor version number. */ + uint16_t flags; /* Capabilities/status flags. */ + uint16_t prod_no; /* Product number. */ + uint16_t prod_rev; /* Product revision number. */ + uint32_t max_buf; /* Maximum buffer size supported. */ +} vds_ver; + +int vds_is_present( void ) +{ + uint8_t __far *vds_flags; + + vds_flags = MK_FP( 0x40, VDS_FLAGS_OFS ); + return( !!(*vds_flags & VDS_PRESENT) ); +} + +int vds_lock_sg( vds_edds __far *edds ); +#pragma aux vds_lock_sg = \ + "mov ax, 8105h" \ + "mov dx, 0" \ + "int 4Bh" \ + "jc error" \ + "xor al, al" \ + "error:" \ + "cbw" \ + parm [es di] value [ax]; + +int vds_unlock_sg( vds_edds __far *edds ); +#pragma aux vds_unlock_sg = \ + "mov ax, 8106h" \ + "mov dx, 0" \ + "int 4Bh" \ + "jc error" \ + "xor al, al" \ + "error:" \ + "cbw" \ + parm [es di] value [ax]; + + +/* + * Convert a real mode 16:16 segmented address to a simple 32-bit + * linear address. + */ +uint32_t vds_real_to_lin( void __far *ptr ) +{ + return( ((uint32_t)FP_SEG( ptr ) << 4) + FP_OFF( ptr ) ); +} + +/* + * Build a VDS-style scatter/gather list, regardless of whether VDS is + * present or not. This routine either calls VDS to do the work or + * trivially creates the list if no remapping is needed. + */ +int vds_build_sg_list( vds_edds __far *edds, void __far *buf, uint32_t len ) +{ + int rc; + + /* NB: The num_avail field in the EDDS must be set correctly! */ + edds->region_size = len; + edds->offset = vds_real_to_lin( buf ); + edds->seg_sel = 0; /* Indicates a linear address. */ + if( vds_is_present() ) { + /* VDS is present, use it. */ + rc = vds_lock_sg( edds ); + } else { + /* No VDS, do it ourselves with one S/G entry. */ + edds->num_used = 1; + edds->u.sg[0].phys_addr = edds->offset; + edds->u.sg[0].size = len; + rc = VDS_SUCCESS; + } + return( rc ); +} + +/* + * Free a VDS-style scatter/gather list, regardless of whether VDS + * is present or not. + */ +int vds_free_sg_list( vds_edds __far *edds ) +{ + int rc; + + if( vds_is_present() ) { + /* VDS is present, use it. */ + rc = vds_unlock_sg( edds ); + } else { + /* No VDS, not much to do. */ + /* We could check here if the EDDS had in fact been built by us. + * But if VDS really went away, what can we do about it anyway? + */ + rc = VDS_SUCCESS; + } + edds->num_used = 0; + return( rc ); +} |