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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2014 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 <stdint.h>
#include <stddef.h>
#include <bootmode.h>
#include <console/console.h>
#include <string.h>
#include <spi-generic.h>
#include <spi_flash.h>
#include <vendorcode/google/chromeos/chromeos.h>
#include "nvm.h"
#include "spi.h"
/* This module assumes the flash is memory mapped just below 4GiB in the
* address space for reading. Also this module assumes an area it erased
* when all bytes read as all 0xff's. */
static struct spi_flash *flash;
static int nvm_init(void)
{
if (flash != NULL)
return 0;
spi_init();
flash = spi_flash_probe(0, 0);
if (!flash) {
printk(BIOS_DEBUG, "Could not find SPI device\n");
return -1;
}
return 0;
}
/*
* Convert memory mapped pointer to flash offset.
*
* This is weak because not every platforms memory-maps the NVM media in the
* same manner. This is a stop-gap solution.
*
* The root of the problem is that users of this API work in memory space for
* both reads and writes, but erase and write must be done in flash space. This
* also only works when the media is memory-mapped, which is no longer
* universally true. The long-term approach should be to rewrite this and its
* users to work in flash space, while using rdev_read() instead of rdev_mmap().
*/
__attribute__((weak))
uint32_t nvm_mmio_to_flash_offset(void *p)
{
return CONFIG_ROM_SIZE + (uintptr_t)p;
}
int nvm_is_erased(const void *start, size_t size)
{
const uint8_t *cur = start;
const uint8_t erased_value = 0xff;
while (size > 0) {
if (*cur != erased_value)
return 0;
cur++;
size--;
}
return 1;
}
int nvm_erase(void *start, size_t size)
{
if (nvm_init() < 0)
return -1;
return spi_flash_erase(flash, nvm_mmio_to_flash_offset(start), size);
}
/* Write data to NVM. Returns 0 on success < 0 on error. */
int nvm_write(void *start, const void *data, size_t size)
{
if (nvm_init() < 0)
return -1;
return spi_flash_write(flash, nvm_mmio_to_flash_offset(start), size,
data);
}
/* Read flash status register to determine if write protect is active */
int nvm_is_write_protected(void)
{
if (nvm_init() < 0)
return -1;
if (IS_ENABLED(CONFIG_CHROMEOS)) {
u8 sr1;
u8 wp_gpio;
u8 wp_spi;
/* Read Write Protect GPIO if available */
wp_gpio = get_write_protect_state();
/* Read Status Register 1 */
if (spi_flash_status(flash, &sr1) < 0) {
printk(BIOS_ERR,
"Failed to read SPI status register 1\n");
return -1;
}
wp_spi = !!(sr1 & 0x80);
printk(BIOS_DEBUG, "SPI flash protection: WPSW=%d SRP0=%d\n",
wp_gpio, wp_spi);
return wp_gpio && wp_spi;
}
return 0;
}
/* Apply protection to a range of flash */
int nvm_protect(void *start, size_t size)
{
#if IS_ENABLED(CONFIG_MRC_SETTINGS_PROTECT)
if (nvm_init() < 0)
return -1;
return spi_flash_protect(nvm_mmio_to_flash_offset(start), size);
#else
return -1;
#endif
}
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