src/cpu/x86/car.c

/*
 * This file is part of the coreboot project.
 *
 * Copyright (C) 2013 Google, Inc.
 *
 * 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.
 */

#include <string.h>
#include <stddef.h>
#include <console/console.h>
#include <cbmem.h>
#include <arch/early_variables.h>
#include <symbols.h>

#if IS_ENABLED(CONFIG_PLATFORM_USES_FSP1_0)
#include <drivers/intel/fsp1_0/fsp_util.h>
#endif
typedef void (* const car_migration_func_t)(void);

extern car_migration_func_t _car_migrate_start;

/*
 * The car_migrated global variable determines if the cache-as-ram space has
 * been migrated to real RAM. It does this by assuming the following things:
 *   1. cache-as-ram space is zero'd out once it is set up.
 *   2. Either the cache-as-ram space is memory-backed after getting torn down
 *      or the space returns 0xff's for each byte read.
 * Based on these 2 attributes there is the ability to tell when the
 * cache-as-ram region has been migrated.
 */
static int car_migrated CAR_GLOBAL;

/** @brief returns pointer to a CAR variable, before or after migration.
 *
 * @param var pointer to the CAR variable
 */
void *car_get_var_ptr(void *var)
{
	char *migrated_base = NULL;
	int offset;
	void * _car_start = &_car_data_start;
	void * _car_end = &_car_data_end;

	/* If the cache-as-ram has not been migrated return the pointer
	 * passed in. */
	if (!car_migrated)
		return var;

	if (var < _car_start || var >= _car_end) {
		printk(BIOS_ERR,
		       "Requesting CAR variable outside of CAR region: %p\n",
		       var);
		return var;
	}

#if IS_ENABLED(CONFIG_PLATFORM_USES_FSP1_0)
	migrated_base=(char *)find_saved_temp_mem(
			*(void **)CBMEM_FSP_HOB_PTR);
	/* FSP 1.0 migrates the entire DCACHE RAM */
	offset = (char *)var - (char *)CONFIG_DCACHE_RAM_BASE;
#else
	migrated_base = cbmem_find(CBMEM_ID_CAR_GLOBALS);
	offset = (char *)var - (char *)_car_start;
#endif

	if (migrated_base == NULL)
		die( "CAR: Could not find migration base!\n");

	return &migrated_base[offset];
}

/*
 * Update a CAR_GLOBAL variable var, originally pointing to CAR region,
 * with the address in migrated CAR region in DRAM.
 */
void *car_sync_var_ptr(void *var)
{
	void ** mig_var = car_get_var_ptr(var);
	void * _car_start = &_car_data_start;
	void * _car_end = &_car_data_end;

	/* Not moved or migrated yet. */
	if (mig_var == var)
		return mig_var;

	/*
	 * Migrate the cbmem console pointer for FSP 1.0 platforms. Otherwise,
	 * keep console buffer in CAR until cbmemc_reinit() moves it.
	 */
	if (*mig_var == _preram_cbmem_console) {
		if (IS_ENABLED(CONFIG_PLATFORM_USES_FSP1_0))
			*mig_var += (char *)mig_var - (char *)var;
		return mig_var;
	}

	/* It's already pointing outside car.global_data. */
	if (*mig_var < _car_start || *mig_var > _car_end)
		return mig_var;

	/* Move the pointer by the same amount the variable storing it was
	 * moved by.
	 */
	*mig_var += (char *)mig_var - (char *)var;

	return mig_var;
}

static void do_car_migrate_variables(void)
{
	void *migrated_base;
	size_t car_size = car_data_size();

	/* Check if already migrated. */
	if (car_migrated)
		return;

	migrated_base = cbmem_add(CBMEM_ID_CAR_GLOBALS, car_size);

	if (migrated_base == NULL) {
		printk(BIOS_ERR, "Could not migrate CAR data!\n");
		return;
	}

	memcpy(migrated_base, &_car_data_start[0], car_size);

	/* Mark that the data has been moved. */
	car_migrated = ~0;
}

static void car_migrate_variables(int is_recovery)
{
	if (!IS_ENABLED(PLATFORM_USES_FSP1_0))
		do_car_migrate_variables();
}
ROMSTAGE_CBMEM_INIT_HOOK(car_migrate_variables)