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/* SPDX-License-Identifier: GPL-2.0-or-later */
#include <boot_device.h>
#include <commonlib/region.h>
#include <console/console.h>
#include <fmap.h>
#include <intelblocks/fast_spi.h>
/*
* BIOS region on the flash is mapped right below 4GiB in the address
* space. However, 256KiB right below 4GiB is decoded by read-only SRAM and not
* boot media.
*
* +-----------+ 0
* | |
* | |
* | |
* | |
* | |
* | |
* | |
* | |
* +--------+ | |
* | IFD | | |
* bios_start +---> +--------+------------------> +-----------+ 4GiB - bios_size
* ^ | | ^ | |
* | | | | | |
* | | | bios_mapped_size | BIOS |
* | | BIOS | | | |
* bios_size | | | | |
* | | | v | |
* | | +------------------> +-----------+ 4GiB - 256KiB
* | | | | Read only |
* v | | | SRAM |
* bios_end +---> +--------+ +-----------+ 4GiB
* | Device |
* | ext |
* +--------+
*
*/
static size_t bios_size;
static struct mem_region_device shadow_dev;
static struct xlate_region_device real_dev;
static void bios_mmap_init(void)
{
size_t size, start, bios_mapped_size;
uintptr_t base;
size = bios_size;
/* If bios_size is initialized, then bail out. */
if (size != 0)
return;
start = fast_spi_get_bios_region(&size);
/* BIOS region is mapped right below 4G. */
base = 4ULL * GiB - size;
/*
* The 256 KiB right below 4G are decoded by readonly SRAM,
* not boot media.
*/
bios_mapped_size = size - 256 * KiB;
mem_region_device_ro_init(&shadow_dev, (void *)base,
bios_mapped_size);
xlate_region_device_ro_init(&real_dev, &shadow_dev.rdev,
start, bios_mapped_size,
CONFIG_ROM_SIZE);
bios_size = size;
/* Check that the CBFS lies within the memory mapped area. It's too
easy to forget the SRAM mapping when crafting an FMAP file. */
struct region cbfs_region;
if (!fmap_locate_area("COREBOOT", &cbfs_region) &&
!region_is_subregion(&real_dev.sub_region, &cbfs_region))
printk(BIOS_CRIT,
"ERROR: CBFS @ %zx size %zx exceeds mem-mapped area @ %zx size %zx\n",
region_offset(&cbfs_region), region_sz(&cbfs_region),
start, bios_mapped_size);
}
const struct region_device *boot_device_ro(void)
{
bios_mmap_init();
return &real_dev.rdev;
}
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