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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2014 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.
*/
#include <arch/early_variables.h>
#include <assert.h>
#include <console/console.h>
#include <spi_flash.h>
#include <string.h>
#include <vb2_api.h>
#include <vboot_nvstorage.h>
#include "chromeos.h"
#include "vbnv.h"
#include "vbnv_layout.h"
#define BLOB_SIZE VB2_NVDATA_SIZE
struct vbnv_flash_ctx {
/* VBNV flash is initialized */
int initialized;
/* Offset of the current nvdata in SPI flash */
int blob_offset;
/* Offset of the topmost nvdata blob in SPI flash */
int top_offset;
/* SPI flash handler used when saving data */
struct spi_flash *flash;
/* FMAP descriptor of the NVRAM area */
struct region_device region;
/* Cache of the current nvdata */
uint8_t cache[BLOB_SIZE];
};
static struct vbnv_flash_ctx vbnv_flash CAR_GLOBAL;
/*
* This code assumes that flash is erased to 1-bits, and write operations can
* only change 1-bits to 0-bits. So if the new contents only change 1-bits to
* 0-bits, we can reuse the current blob.
*/
static inline uint8_t erase_value(void)
{
return 0xff;
}
static inline int can_overwrite(uint8_t current, uint8_t new)
{
return (current & new) == new;
}
static int init_vbnv(void)
{
struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
uint8_t buf[BLOB_SIZE];
uint8_t empty_blob[BLOB_SIZE];
int offset;
int i;
if (vboot_named_region_device("RW_NVRAM", &ctx->region) ||
region_device_sz(&ctx->region) < BLOB_SIZE) {
printk(BIOS_ERR, "%s: failed to locate NVRAM\n", __func__);
return 1;
}
/* Prepare an empty blob to compare against. */
for (i = 0; i < BLOB_SIZE; i++)
empty_blob[i] = erase_value();
offset = 0;
ctx->top_offset = region_device_sz(&ctx->region) - BLOB_SIZE;
/*
* after the loop, offset is supposed to point the blob right before
* the first empty blob, the last blob in the nvram if there is no
* empty blob, or the base of the region if the nvram has never been
* used.
*/
for (i = 0; i <= ctx->top_offset; i += BLOB_SIZE) {
if (rdev_readat(&ctx->region, buf, i, BLOB_SIZE) < 0) {
printk(BIOS_ERR, "failed to read nvdata\n");
return 1;
}
if (!memcmp(buf, empty_blob, BLOB_SIZE))
break;
offset = i;
}
/* reread the nvdata and write it to the cache */
if (rdev_readat(&ctx->region, ctx->cache, offset, BLOB_SIZE) < 0) {
printk(BIOS_ERR, "failed to read nvdata\n");
return 1;
}
ctx->blob_offset = offset;
ctx->initialized = 1;
return 0;
}
static void vbnv_is_erasable(void)
{
/*
* We check whether the region is aligned or not in advance to ensure
* we can erase the region when it's all used up.
*
* The region offset & size are determined by fmap.dts yet the check can
* be confidently done only by the spi flash driver. We use the same
* check as the one used by spi_flash_cmd_erase, which happens to be
* common to all the spi flash parts we support.
*
* TODO: Check by calling can_erase implemented by each spi flash driver
*/
struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
assert(!(region_device_offset(&ctx->region) % ctx->flash->sector_size));
assert(!(region_device_sz(&ctx->region) % ctx->flash->sector_size));
}
static int vbnv_flash_probe(void)
{
struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
if (!ctx->flash) {
ctx->flash = spi_flash_probe(CONFIG_BOOT_MEDIA_SPI_BUS, 0);
if (!ctx->flash) {
printk(BIOS_ERR, "failed to probe spi flash\n");
return 1;
}
/*
* Called here instead of init_vbnv to reduce impact on boot
* speed.
*/
vbnv_is_erasable();
}
/*
* Handle the case where spi_flash_probe returns a CAR_GLOBAL
* in early execution on x86 but then later is moved to RAM.
*/
ctx->flash = car_get_var_ptr(ctx->flash);
return 0;
}
static int erase_nvram(void)
{
struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
if (vbnv_flash_probe())
return 1;
if (ctx->flash->erase(ctx->flash, region_device_offset(&ctx->region),
region_device_sz(&ctx->region))) {
printk(BIOS_ERR, "failed to erase nvram\n");
return 1;
}
printk(BIOS_INFO, "nvram is cleared\n");
return 0;
}
void read_vbnv_flash(uint8_t *vbnv_copy)
{
struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
if (!ctx->initialized)
if (init_vbnv())
return; /* error */
memcpy(vbnv_copy, ctx->cache, BLOB_SIZE);
}
void save_vbnv_flash(const uint8_t *vbnv_copy)
{
struct vbnv_flash_ctx *ctx = car_get_var_ptr(&vbnv_flash);
int new_offset;
int i;
if (!ctx->initialized)
if (init_vbnv())
return; /* error */
/* Bail out if there have been no changes. */
if (!memcmp(vbnv_copy, ctx->cache, BLOB_SIZE))
return;
new_offset = ctx->blob_offset;
/* See if we can overwrite the current blob with the new one */
for (i = 0; i < BLOB_SIZE; i++) {
if (!can_overwrite(ctx->cache[i], vbnv_copy[i])) {
/* unable to overwrite. need to use the next blob */
new_offset += BLOB_SIZE;
if (new_offset > ctx->top_offset) {
if (erase_nvram())
return; /* error */
new_offset = 0;
}
break;
}
}
if (!vbnv_flash_probe() &&
!ctx->flash->write(ctx->flash,
region_device_offset(&ctx->region) + new_offset,
BLOB_SIZE, vbnv_copy)) {
/* write was successful. safely move pointer forward */
ctx->blob_offset = new_offset;
memcpy(ctx->cache, vbnv_copy, BLOB_SIZE);
} else {
printk(BIOS_ERR, "failed to save nvdata\n");
}
}
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