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/*
* This file is part of the coreboot project.
*
*
* 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 <types.h>
#include <security/vboot/vbnv.h>
#include <security/vboot/vbnv_layout.h>
static int vbnv_initialized;
static uint8_t vbnv[VBOOT_VBNV_BLOCK_SIZE];
/* Return CRC-8 of the data, using x^8 + x^2 + x + 1 polynomial. */
static uint8_t crc8_vbnv(const uint8_t *data, int len)
{
unsigned int 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 vbnv_reset(uint8_t *vbnv_copy)
{
memset(vbnv_copy, 0, VBOOT_VBNV_BLOCK_SIZE);
}
/* Read VBNV data into cache. */
static void vbnv_setup(void)
{
if (!vbnv_initialized) {
read_vbnv(vbnv);
vbnv_initialized = 1;
}
}
/* Verify VBNV header and checksum. */
int verify_vbnv(uint8_t *vbnv_copy)
{
return (HEADER_SIGNATURE == (vbnv_copy[HEADER_OFFSET] & HEADER_MASK)) &&
(crc8_vbnv(vbnv_copy, CRC_OFFSET) == vbnv_copy[CRC_OFFSET]);
}
/* Re-generate VBNV checksum. */
void regen_vbnv_crc(uint8_t *vbnv_copy)
{
vbnv_copy[CRC_OFFSET] = crc8_vbnv(vbnv_copy, CRC_OFFSET);
}
/*
* Read VBNV data from configured storage backend.
* If VBNV verification fails, reset the vbnv copy.
*/
void read_vbnv(uint8_t *vbnv_copy)
{
if (CONFIG(VBOOT_VBNV_CMOS))
read_vbnv_cmos(vbnv_copy);
else if (CONFIG(VBOOT_VBNV_EC))
read_vbnv_ec(vbnv_copy);
else if (CONFIG(VBOOT_VBNV_FLASH))
read_vbnv_flash(vbnv_copy);
/* Check data for consistency */
if (!verify_vbnv(vbnv_copy))
vbnv_reset(vbnv_copy);
}
/*
* Write VBNV data to configured storage backend.
* This assumes that the caller has updated the CRC already.
*/
void save_vbnv(const uint8_t *vbnv_copy)
{
if (CONFIG(VBOOT_VBNV_CMOS))
save_vbnv_cmos(vbnv_copy);
else if (CONFIG(VBOOT_VBNV_EC))
save_vbnv_ec(vbnv_copy);
else if (CONFIG(VBOOT_VBNV_FLASH))
save_vbnv_flash(vbnv_copy);
/* Clear initialized flag to force cached data to be updated */
vbnv_initialized = 0;
}
/* Read the USB Device Controller(UDC) enable flag from VBNV. */
int vbnv_udc_enable_flag(void)
{
vbnv_setup();
return (vbnv[DEV_FLAGS_OFFSET] & DEV_ENABLE_UDC) ? 1 : 0;
}
void vbnv_init(uint8_t *vbnv_copy)
{
if (CONFIG(VBOOT_VBNV_CMOS))
vbnv_init_cmos(vbnv_copy);
read_vbnv(vbnv_copy);
}
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