src/northbridge/intel/nehalem/ram_calc.c

/*
 * This file is part of the coreboot project.
 *
 * Copyright (C) 2012 Google LLC
 * Copyright (C) 2013 Vladimir Serbinenko.
 *
 * 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.
 */

#define __SIMPLE_DEVICE__

#include <arch/cpu.h>
#include <device/pci_ops.h>
#include <cbmem.h>
#include <console/console.h>
#include <cpu/intel/romstage.h>
#include <cpu/x86/mtrr.h>
#include <program_loading.h>
#include <cpu/intel/smm/gen1/smi.h>
#include "nehalem.h"

static uintptr_t smm_region_start(void)
{
	/* Base of TSEG is top of usable DRAM */
	uintptr_t tom = pci_read_config32(PCI_DEV(0,0,0), TSEG);
	return tom;
}

u32 northbridge_get_tseg_base(void)
{
	return (u32)smm_region_start & ~1;
}

void *cbmem_top(void)
{
	return (void *) smm_region_start();
}

#define ROMSTAGE_RAM_STACK_SIZE 0x5000

/* platform_enter_postcar() determines the stack to use after
 * cache-as-ram is torn down as well as the MTRR settings to use,
 * and continues execution in postcar stage. */
void platform_enter_postcar(void)
{
	struct postcar_frame pcf;
	uintptr_t top_of_ram;

	if (postcar_frame_init(&pcf, ROMSTAGE_RAM_STACK_SIZE))
		die("Unable to initialize postcar frame.\n");

	/* Cache the ROM as WP just below 4GiB. */
	postcar_frame_add_romcache(&pcf, MTRR_TYPE_WRPROT);

	/* Cache RAM as WB from 0 -> CACHE_TMP_RAMTOP. */
	postcar_frame_add_mtrr(&pcf, 0, CACHE_TMP_RAMTOP, MTRR_TYPE_WRBACK);

	/* Cache at least 8 MiB below the top of ram, and at most 8 MiB
	 * above top of the ram. This satisfies MTRR alignment requirement
	 * with different TSEG size configurations.
	 */
	top_of_ram = ALIGN_DOWN((uintptr_t)cbmem_top(), 8*MiB);
	postcar_frame_add_mtrr(&pcf, top_of_ram - 8*MiB, 8*MiB, MTRR_TYPE_WRBACK);
	postcar_frame_add_mtrr(&pcf, top_of_ram, 8*MiB, MTRR_TYPE_WRBACK);

	run_postcar_phase(&pcf);

	/* We do not return here. */
}