src/northbridge/intel/i945/ram_calc.c

/*
 * This file is part of the coreboot project.
 *
 * Copyright (C) 2007-2009 coresystems GmbH
 *
 * 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.
 */

// Use simple device model for this file even in ramstage
#define __SIMPLE_DEVICE__

#include <arch/io.h>
#include <cbmem.h>
#include "i945.h"
#include <console/console.h>
#include <cpu/intel/romstage.h>

static uintptr_t smm_region_start(void)
{
	uintptr_t tom;

	if (pci_read_config8(PCI_DEV(0, 0x0, 0), DEVEN) & (DEVEN_D2F0 | DEVEN_D2F1)) {
		/* IGD enabled, get top of Memory from BSM register */
		tom = pci_read_config32(PCI_DEV(0,2,0), BSM);
	} else {
		tom = (pci_read_config8(PCI_DEV(0,0,0), TOLUD) & 0xf7) << 24;
	}

	/* if TSEG enabled subtract size */
	switch(pci_read_config8(PCI_DEV(0, 0, 0), ESMRAM) & 0x07) {
	case 0x01:
		/* 1MB TSEG */
		tom -= 0x100000;
		break;
	case 0x03:
		/* 2MB TSEG */
		tom -= 0x200000;
		break;
	case 0x05:
		/* 8MB TSEG */
		tom -= 0x800000;
		break;
	default:
		/* TSEG either disabled or invalid */
		break;
	}
	return tom;
}

/* Depending of UMA and TSEG configuration, TSEG might start at any
 * 1 MiB aligment. As this may cause very greedy MTRR setup, push
 * CBMEM top downwards to 4 MiB boundary.
 */
void *cbmem_top(void)
{
	uintptr_t top_of_ram = ALIGN_DOWN(smm_region_start(), 4*MiB);
	return (void *) top_of_ram;
}

/** Decodes used Graphics Mode Select (GMS) to kilobytes. */
u32 decode_igd_memory_size(const u32 gms)
{
	static const u16 ggc2uma[] = { 0, 1, 4, 8, 16, 32,
			48, 64 };

	if (gms > ARRAY_SIZE(ggc2uma))
		die("Bad Graphics Mode Select (GMS) setting.\n");

	return ggc2uma[gms] << 10;
}

void *setup_stack_and_mtrrs(void)
{
	return (void*)CONFIG_RAMTOP;
}