src/cpu/x86/smm/smihandler.c

/*
 * This file is part of the coreboot project.
 *
 * Copyright (C) 2008-2009 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
 * MA 02110-1301 USA
 */

#include <arch/io.h>
#include <arch/romcc_io.h>
#include <console/console.h>
#include <cpu/x86/cache.h>
#include <cpu/x86/smm.h>

typedef enum { SMI_LOCKED, SMI_UNLOCKED } smi_semaphore;

/* SMI multiprocessing semaphore */
static volatile smi_semaphore smi_handler_status = SMI_UNLOCKED;

static int smi_obtain_lock(void)
{
	u8 ret = SMI_LOCKED;

	asm volatile (
		"movb %2, %%al\n"
		"xchgb %%al, %1\n"
		"movb %%al, %0\n"
		: "=g" (ret), "=m" (smi_handler_status)
		: "g" (SMI_LOCKED)
		: "eax"
	);

	return (ret == SMI_UNLOCKED);
}

static void smi_release_lock(void)
{
	asm volatile (
		"movb %1, %%al\n"
		"xchgb %%al, %0\n"
		: "=m" (smi_handler_status)
		: "g" (SMI_UNLOCKED)
		: "eax"
	);
}

#define LAPIC_ID 0xfee00020
static inline __attribute__((always_inline)) unsigned long nodeid(void)
{
	return (*((volatile unsigned long *)(LAPIC_ID)) >> 24);
}

void io_trap_handler(int smif)
{
	/* If a handler function handled a given IO trap, it
	 * shall return a non-zero value
	 */
        printk(BIOS_DEBUG, "SMI function trap 0x%x: ", smif);

	if (southbridge_io_trap_handler(smif))
		return;

	if (mainboard_io_trap_handler(smif))
		return;

	printk(BIOS_DEBUG, "Unknown function\n");
}

/**
 * @brief Set the EOS bit
 */
static void smi_set_eos(void)
{
	southbridge_smi_set_eos();
}

static u32 pci_orig;

/**
 * @brief Backup PCI address to make sure we do not mess up the OS
 */
static void smi_backup_pci_address(void)
{
	pci_orig = inl(0xcf8);
}

/**
 * @brief Restore PCI address previously backed up
 */
static void smi_restore_pci_address(void)
{
	outl(pci_orig, 0xcf8);
}

/**
 * @brief Interrupt handler for SMI#
 *
 * @param smm_revision revision of the smm state save map
 */

void smi_handler(u32 smm_revision)
{
	unsigned int node;
	smm_state_save_area_t state_save;

	/* Are we ok to execute the handler? */
	if (!smi_obtain_lock()) {
		/* For security reasons we don't release the other CPUs
		 * until the CPU with the lock is actually done
		 */
		while (smi_handler_status == SMI_LOCKED) /* wait */ ;
		return;
	}

	smi_backup_pci_address();

	node=nodeid();

	console_init();

	printk(BIOS_SPEW, "\nSMI# #%d\n", node);

	switch (smm_revision) {
	case 0x00030002:
	case 0x00030007:
		state_save.type = LEGACY;
		state_save.legacy_state_save = (legacy_smm_state_save_area_t *)
			(0xa8000 + 0x7e00 - (node * 0x400));
		break;
	case 0x00030100:
		state_save.type = EM64T;
		state_save.em64t_state_save = (em64t_smm_state_save_area_t *)
			(0xa8000 + 0x7d00 - (node * 0x400));
		break;
	case 0x00030064:
		state_save.type = AMD64;
		state_save.amd64_state_save = (amd64_smm_state_save_area_t *)
			(0xa8000 + 0x7e00 - (node * 0x400));
		break;
	default:
		printk(BIOS_DEBUG, "smm_revision: 0x%08x\n", smm_revision);
		printk(BIOS_DEBUG, "SMI# not supported on your CPU\n");
		/* Don't release lock, so no further SMI will happen,
		 * if we don't handle it anyways.
		 */
		return;
	}

	/* Call chipset specific SMI handlers. */
	if (cpu_smi_handler)
		cpu_smi_handler(node, &state_save);
	if (northbridge_smi_handler)
		northbridge_smi_handler(node, &state_save);
	if (southbridge_smi_handler)
		southbridge_smi_handler(node, &state_save);

	smi_restore_pci_address();

	smi_release_lock();

	/* De-assert SMI# signal to allow another SMI */
	smi_set_eos();
}