boot/zephyr/flash_map_legacy.c

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

/**
 * @file
 * @brief Legacy flash fallbacks
 *
 * This file contains hacks for flash drivers without page layout
 * support. They're hacks because they guess a page layout that may be
 * incorrect, but is likely to "work". Needless to say, such guesswork
 * is undesirable in trusted bootloader code.
 *
 * The behavior is:
 *
 * - If FLASH_AREA_IMAGE_SECTOR_SIZE is defined (this was used by
 *   older Zephyr ports), the image sectors have uniform sector sizes.
 *   We also assume that's the size of the scratch sectors.
 *
 * - Otherwise, we assume that the size of the entire scratch area is
 *   a least common multiple of all sector sizes, and use that as
 *   FLASH_AREA_IMAGE_SECTOR_SIZE.
 */

#define BOOT_LOG_LEVEL BOOT_LOG_LEVEL_INFO
#include "bootutil/bootutil_log.h"

#include <flash_map/flash_map.h>
#include <inttypes.h>
#include <target.h>

#warning "The flash driver lacks page layout support; falling back on hacks."

#if !defined(FLASH_AREA_IMAGE_SECTOR_SIZE)
#define FLASH_AREA_IMAGE_SECTOR_SIZE FLASH_AREA_IMAGE_SCRATCH_SIZE
#endif

extern int flash_area_get_bounds(int idx, uint32_t *off, uint32_t *len);

int flash_area_to_sectors(int idx, int *cnt, struct flash_area *ret)
{
    uint32_t off;
    uint32_t len;
    uint32_t max_cnt = *cnt;
    uint32_t rem_len;

    if (flash_area_get_bounds(idx, &off, &len)) {
        return -1;
    }

    if (*cnt < 1) {
        return -1;
    }

    rem_len = len;
    *cnt = 0;
    while (rem_len > 0 && *cnt < max_cnt) {
        if (rem_len < FLASH_AREA_IMAGE_SECTOR_SIZE) {
            BOOT_LOG_ERR("area %d size 0x%x not divisible by sector size 0x%x",
                     idx, len, FLASH_AREA_IMAGE_SECTOR_SIZE);
            return -1;
        }

        ret[*cnt].fa_id = idx;
        ret[*cnt].fa_device_id = 0;
        ret[*cnt].pad16 = 0;
        ret[*cnt].fa_off = off + (FLASH_AREA_IMAGE_SECTOR_SIZE * (*cnt));
        ret[*cnt].fa_size = FLASH_AREA_IMAGE_SECTOR_SIZE;
        *cnt = *cnt + 1;
        rem_len -= FLASH_AREA_IMAGE_SECTOR_SIZE;
    }

    if (*cnt >= max_cnt) {
        BOOT_LOG_ERR("flash area %d sector count overflow", idx);
        return -1;
    }

    return 0;
}

/*
 * Lookup the sector map for a given flash area.  This should fill in
 * `ret` with all of the sectors in the area.  `*cnt` will be set to
 * the storage at `ret` and should be set to the final number of
 * sectors in this area.
 */
int flash_area_get_sectors(int idx, uint32_t *cnt, struct flash_sector *ret)
{
    uint32_t off;
    uint32_t len;
    uint32_t max_cnt = *cnt;
    uint32_t rem_len;

    if (flash_area_get_bounds(idx, &off, &len)) {
        return -1;
    }

    if (*cnt < 1) {
        return -1;
    }

    rem_len = len;
    *cnt = 0;
    while (rem_len > 0 && *cnt < max_cnt) {
        if (rem_len < FLASH_AREA_IMAGE_SECTOR_SIZE) {
            BOOT_LOG_ERR("area %d size 0x%x not divisible by sector size 0x%x",
                         idx, len, FLASH_AREA_IMAGE_SECTOR_SIZE);
            return -1;
        }

        ret[*cnt].fs_off = FLASH_AREA_IMAGE_SECTOR_SIZE * (*cnt);
        ret[*cnt].fs_size = FLASH_AREA_IMAGE_SECTOR_SIZE;
        *cnt = *cnt + 1;
        rem_len -= FLASH_AREA_IMAGE_SECTOR_SIZE;
    }

    if (*cnt >= max_cnt) {
        BOOT_LOG_ERR("flash area %d sector count overflow", idx);
        return -1;
    }

    return 0;
}