/* SPDX-License-Identifier: GPL-2.0-only */

#include <types.h>
#include <acpi/acpi.h>
#include <acpi/acpigen.h>
#include <device/device.h>
#include <device/pci_ops.h>
#include "i945.h"

unsigned long acpi_fill_mcfg(unsigned long current)
{
	struct device *dev;
	u32 pciexbar = 0;
	u32 pciexbar_reg;
	int max_buses;

	dev = pcidev_on_root(0, 0);
	if (!dev)
		return current;

	pciexbar_reg = pci_read_config32(dev, PCIEXBAR);

	// MMCFG not supported or not enabled.
	if (!(pciexbar_reg & (1 << 0)))
		return current;

	switch ((pciexbar_reg >> 1) & 3) {
	case 0: // 256MB
		pciexbar = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28));
		max_buses = 256;
		break;
	case 1: // 128M
		pciexbar = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28)|(1 << 27));
		max_buses = 128;
		break;
	case 2: // 64M
		pciexbar = pciexbar_reg & ((1 << 31)|(1 << 30)|(1 << 29)|(1 << 28)|(1 << 27)|(1 << 26));
		max_buses = 64;
		break;
	default: // RSVD
		return current;
	}

	if (!pciexbar)
		return current;

	current += acpi_create_mcfg_mmconfig((acpi_mcfg_mmconfig_t *) current,
			pciexbar, 0x0, 0x0, max_buses - 1);

	return current;
}