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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2012 The Chromium OS Authors. All rights reserved.
*
* 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; version 2 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.
*/
#include <stdint.h>
#include <string.h>
#include <arch/io.h>
#include <arch/ebda.h>
#include <commonlib/endian.h>
#include <console/console.h>
static void *get_ebda_start(void)
{
return (void *)((uintptr_t)DEFAULT_EBDA_SEGMENT << 4);
}
static bool is_length_valid(size_t dlength)
{
/* Check if input data length is > DEFAULT_EBDA_SIZE */
if (dlength > DEFAULT_EBDA_SIZE)
return false;
/* Valid data length */
return true;
}
/*
* EBDA area is representing a 1KB memory area just below
* the top of conventional memory (below 1MB)
*/
/*
* write_ebda_data is a wrapper function to write into EBDA area
*
* data = data to be written into EBDA area
* length = input data size.
*/
void write_ebda_data(const void *data, size_t length)
{
void *ebda;
if (!is_length_valid(length))
die("Input data length is > EBDA default size (1KiB)!");
ebda = get_ebda_start();
memcpy(ebda, data, length);
}
/*
* read_ebda_data is a wrapper function to read from EBDA area
*
* data = data read from EBDA area based on input size
* length = read data size.
*/
void read_ebda_data(void *data, size_t length)
{
void *ebda;
if (!is_length_valid(length))
die("Input data length is > EBDA default size (1KiB)!");
ebda = get_ebda_start();
memcpy(data, ebda, length);
}
void setup_ebda(u32 low_memory_size, u16 ebda_segment, u16 ebda_size)
{
u16 low_memory_kb;
u16 ebda_kb;
void *ebda;
if (!low_memory_size || !ebda_segment || !ebda_size)
return;
low_memory_kb = low_memory_size >> 10;
ebda_kb = ebda_size >> 10;
ebda = get_ebda_start();
/* clear BIOS DATA AREA */
zero_n(X86_BDA_BASE, X86_BDA_SIZE);
/* Avoid unaligned write16() since it's undefined behavior */
write_le16(X86_EBDA_LOWMEM, low_memory_kb);
write_le16(X86_EBDA_SEGMENT, ebda_segment);
/* Set up EBDA */
zero_n(ebda, ebda_size);
write_le16(ebda, ebda_kb);
}
void setup_default_ebda(void)
{
setup_ebda(DEFAULT_EBDA_LOWMEM,
DEFAULT_EBDA_SEGMENT,
DEFAULT_EBDA_SIZE);
}
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