/*
 * Copyright (c) 2010-2016 Richard Braun.
 *
 * 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 3 of the License, or
 * (at your option) 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, see <http://www.gnu.org/licenses/>.
 */

#ifndef X86_BIOSMEM_H
#define X86_BIOSMEM_H

#include <stdbool.h>

#include <kern/init.h>
#include <machine/multiboot.h>
#include <machine/types.h>

/*
 * BIOS Data Area.
 */
#define BIOSMEM_BDA_ADDR    0x400
#define BIOSMEM_BDA_SIZE    0x100

/*
 * Address where the address of the Extended BIOS Data Area segment can be
 * found.
 */
#define BIOSMEM_EBDA_PTR 0x40e

/*
 * Significant low memory addresses.
 *
 * The first 64 KiB are reserved for various reasons (e.g. to preserve BIOS
 * data and to work around data corruption on some hardware).
 */
#define BIOSMEM_BASE        0x010000
#define BIOSMEM_BASE_END    0x0a0000
#define BIOSMEM_EXT_ROM     0x0e0000
#define BIOSMEM_ROM         0x0f0000
#define BIOSMEM_END         0x100000

/*
 * Report reserved addresses to the biosmem module.
 *
 * Once all boot data have been registered, the user can set up the
 * early page allocator.
 *
 * If the range is marked temporary, it will be unregistered once
 * the boot data have been saved/consumed so that their backing
 * pages are loaded into the VM system.
 *
 * This function is called before paging is enabled.
 */
void biosmem_register_boot_data(phys_addr_t start, phys_addr_t end,
                                bool temporary);

/*
 * Initialize the early page allocator.
 *
 * This function uses the memory map provided by the boot loader along
 * with the registered boot data addresses to set up a heap of free pages
 * of physical memory.
 *
 * This function is called before paging is enabled.
 */
void biosmem_bootstrap(const struct multiboot_raw_info *mbi);

/*
 * Allocate contiguous physical pages during bootstrap.
 *
 * The pages returned are guaranteed to be part of the direct physical
 * mapping when paging is enabled.
 *
 * This function should only be used to allocate initial page table pages.
 * Those pages are later loaded into the VM system (as reserved pages)
 * which means they can be freed like other regular pages. Users should
 * fix up the type of those pages once the VM system is initialized.
 *
 * This function is called before paging is enabled.
 */
void * biosmem_bootalloc(unsigned int nr_pages);

/*
 * Return a pointer to a copy of the BIOS Data Area.
 *
 * The region denoted by the returned address is of size BIOSMEM_BDA_SIZE,
 * and is only valid during initialization.
 */
const void * biosmem_get_bda(void);

/*
 * Return the limit of physical memory that can be directly mapped.
 */
phys_addr_t biosmem_directmap_end(void);

/*
 * This init operation provides :
 *  - heaps of physical memory are loaded by the VM system
 */
INIT_OP_DECLARE(biosmem_setup);

#endif /* X86_BIOSMEM_H */