flash.c

/*
 * This file is part of the TREZOR project, https://trezor.io/
 *
 * Copyright (c) SatoshiLabs
 *
 * 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <string.h>
#include <libopencm3/stm32/flash.h>

#include "common.h"
#include "flash.h"
#include "memory.h"
#include "supervise.h"

static const uint32_t FLASH_SECTOR_TABLE[FLASH_SECTOR_COUNT + 1] = {
    [ 0] = 0x08000000, // - 0x08003FFF |  16 KiB
    [ 1] = 0x08004000, // - 0x08007FFF |  16 KiB
    [ 2] = 0x08008000, // - 0x0800BFFF |  16 KiB
    [ 3] = 0x0800C000, // - 0x0800FFFF |  16 KiB
    [ 4] = 0x08010000, // - 0x0801FFFF |  64 KiB
    [ 5] = 0x08020000, // - 0x0803FFFF | 128 KiB
    [ 6] = 0x08040000, // - 0x0805FFFF | 128 KiB
    [ 7] = 0x08060000, // - 0x0807FFFF | 128 KiB
    [ 8] = 0x08080000, // - 0x0809FFFF | 128 KiB
    [ 9] = 0x080A0000, // - 0x080BFFFF | 128 KiB
    [10] = 0x080C0000, // - 0x080DFFFF | 128 KiB
    [11] = 0x080E0000, // - 0x080FFFFF | 128 KiB
    [12] = 0x08100000, // last element - not a valid sector
};

static secbool flash_check_success(uint32_t status)
{
    return (status & (FLASH_SR_PGAERR | FLASH_SR_PGPERR | FLASH_SR_PGSERR | FLASH_SR_WRPERR)) ? secfalse : sectrue;
}

void flash_init(void)
{
}

secbool flash_unlock_write(void)
{
    svc_flash_unlock();
    return sectrue;
}

secbool flash_lock_write(void)
{
    return flash_check_success(svc_flash_lock());
}

const void *flash_get_address(uint8_t sector, uint32_t offset, uint32_t size)
{
    if (sector >= FLASH_SECTOR_COUNT) {
        return NULL;
    }
    const uint32_t addr = FLASH_SECTOR_TABLE[sector] + offset;
    const uint32_t next = FLASH_SECTOR_TABLE[sector + 1];
    if (addr + size > next) {
        return NULL;
    }
    return (const void *) FLASH_PTR(addr);
}

secbool flash_erase(uint8_t sector)
{
    ensure(flash_unlock_write(), NULL);
    svc_flash_erase_sector(sector);
    ensure(flash_lock_write(), NULL);

    // Check whether the sector was really deleted (contains only 0xFF).
    const uint32_t addr_start = FLASH_SECTOR_TABLE[sector], addr_end = FLASH_SECTOR_TABLE[sector + 1];
    for (uint32_t addr = addr_start; addr < addr_end; addr += 4) {
        if (*((const uint32_t *)FLASH_PTR(addr)) != 0xFFFFFFFF) {
            return secfalse;
        }
    }
    return sectrue;
}

secbool flash_write_byte(uint8_t sector, uint32_t offset, uint8_t data)
{
    uint8_t *address = (uint8_t *) flash_get_address(sector, offset, 1);
    if (address == NULL) {
        return secfalse;
    }

    if ((*address & data) != data) {
        return secfalse;
    }

    svc_flash_program(FLASH_CR_PROGRAM_X8);
    *(volatile uint8_t *) address = data;

    if (*address != data) {
        return secfalse;
    }

    return sectrue;
}

secbool flash_write_word(uint8_t sector, uint32_t offset, uint32_t data)
{
    uint32_t *address = (uint32_t *) flash_get_address(sector, offset, 4);
    if (address == NULL) {
        return secfalse;
    }

    if (offset % 4 != 0) {
        return secfalse;
    }

    if ((*address & data) != data) {
        return secfalse;
    }

    svc_flash_program(FLASH_CR_PROGRAM_X32);
    *(volatile uint32_t *) address = data;

    if (*address != data) {
        return secfalse;
    }

    return sectrue;
}