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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2011 The ChromiumOS Authors. All rights reserved.
*
* 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 <types.h>
#include <string.h>
#include <console/console.h>
#include <arch/early_variables.h>
#include <ec/google/chromeec/ec.h>
#include "chromeos.h"
#define VBNV_BLOCK_SIZE 16 /* Size of NV storage block in bytes */
/* Constants for NV storage. We use this rather than structs and
* bitfields so the data format is consistent across platforms and
* compilers.
*/
#define HEADER_OFFSET 0
#define HEADER_MASK 0xC0
#define HEADER_SIGNATURE 0x40
#define HEADER_FIRMWARE_SETTINGS_RESET 0x20
#define HEADER_KERNEL_SETTINGS_RESET 0x10
#define BOOT_OFFSET 1
#define BOOT_DEBUG_RESET_MODE 0x80
#define BOOT_DISABLE_DEV_REQUEST 0x40
#define BOOT_OPROM_NEEDED 0x20
#define BOOT_TRY_B_COUNT_MASK 0x0F
#define RECOVERY_OFFSET 2
#define LOCALIZATION_OFFSET 3
#define DEV_FLAGS_OFFSET 4
#define DEV_BOOT_USB_MASK 0x01
#define DEV_BOOT_SIGNED_ONLY_MASK 0x02
#define KERNEL_FIELD_OFFSET 11
#define CRC_OFFSET 15
static int vbnv_initialized CAR_GLOBAL;
static uint8_t vbnv[VBNV_BLOCK_SIZE] CAR_GLOBAL;
/* Wrappers for accessing the variables marked as CAR_GLOBAL. */
static inline int is_vbnv_initialized(void)
{
return car_get_var(vbnv_initialized);
}
static inline uint8_t *vbnv_data_addr(int index)
{
uint8_t *vbnv_arr = car_get_var_ptr(vbnv);
return &vbnv_arr[index];
}
static inline uint8_t vbnv_data(int index)
{
return *vbnv_data_addr(index);
}
/* Return CRC-8 of the data, using x^8 + x^2 + x + 1 polynomial. A
* table-based algorithm would be faster, but for only 15 bytes isn't
* worth the code size.
*/
static uint8_t crc8(const uint8_t * data, int len)
{
unsigned crc = 0;
int i, j;
for (j = len; j; j--, data++) {
crc ^= (*data << 8);
for (i = 8; i; i--) {
if (crc & 0x8000)
crc ^= (0x1070 << 3);
crc <<= 1;
}
}
return (uint8_t) (crc >> 8);
}
void read_vbnv(uint8_t *vbnv_copy)
{
google_chromeec_vbnv_context(1, vbnv_copy, VBNV_BLOCK_SIZE);
/* Check data for consistency */
if ((HEADER_SIGNATURE != (vbnv_copy[HEADER_OFFSET] & HEADER_MASK))
|| (crc8(vbnv_copy, CRC_OFFSET) != vbnv_copy[CRC_OFFSET])) {
/* Data is inconsistent (bad CRC or header),
* so reset to defaults
*/
memset(vbnv_copy, 0, VBNV_BLOCK_SIZE);
vbnv_copy[HEADER_OFFSET] =
(HEADER_SIGNATURE | HEADER_FIRMWARE_SETTINGS_RESET |
HEADER_KERNEL_SETTINGS_RESET);
}
}
void save_vbnv(const uint8_t *vbnv_copy)
{
google_chromeec_vbnv_context(0, (uint8_t *)vbnv_copy, VBNV_BLOCK_SIZE);
}
static void vbnv_setup(void)
{
read_vbnv(vbnv_data_addr(0));
car_set_var(vbnv_initialized, 1);
}
int get_recovery_mode_from_vbnv(void)
{
if (!is_vbnv_initialized())
vbnv_setup();
return vbnv_data(RECOVERY_OFFSET);
}
int vboot_wants_oprom(void)
{
if (!is_vbnv_initialized())
vbnv_setup();
return (vbnv_data(BOOT_OFFSET) & BOOT_OPROM_NEEDED) ? 1 : 0;
}
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