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/*
 * Linksys boot counter reset code for mtd
 *
 * Copyright (C) 2013 Jonas Gorski <jogo@openwrt.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License v2
 * as published by the Free Software Foundation.
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <endian.h>
#include <string.h>
#include <errno.h>
#include <stdint.h>

#include <sys/ioctl.h>
#include <mtd/mtd-user.h>

#include "mtd.h"

#define BOOTCOUNT_MAGIC 0x20110811

struct bootcounter {
        uint32_t magic;
        uint32_t count;
        uint32_t checksum;
};

static char page[2048];

int mtd_resetbc(const char *mtd)
{
        struct mtd_info_user mtd_info;
        struct bootcounter *curr = (struct bootcounter *)page;
        unsigned int i;
        int last_count = 0;
        int num_bc;
        int fd;
        int ret;

        fd = mtd_check_open(mtd);

        if (ioctl(fd, MEMGETINFO, &mtd_info) < 0) {
                fprintf(stderr, "failed to get mtd info!\n");
                return -1;
        }

        num_bc = mtd_info.size / 16;

        for (i = 0; i < num_bc; i++) {
                pread(fd, curr, sizeof(*curr), i * 16);

                if (curr->magic != (BOOTCOUNT_MAGIC) && curr->magic != 0xffffffff) {
                        fprintf(stderr, "unexpected magic %08x, bailing out\n", curr->magic);
                        goto out;
                }

                if (curr->magic == 0xffffffff)
                        break;

                last_count = curr->count;
        }

        /* no need to do writes when last boot count is already 0 */
        if (last_count == 0)
                goto out;


        if (i == num_bc) {
                struct erase_info_user erase_info;
                erase_info.start = 0;
                erase_info.length = mtd_info.size;

                /* erase block */
                ret = ioctl(fd, MEMERASE, &erase_info);
                if (ret < 0) {
                        fprintf(stderr, "failed to erase block: %i\n", ret);
                        return -1;
                }

                i = 0;
        }

        memset(curr, 0xff, 16);

        curr->magic = BOOTCOUNT_MAGIC;
        curr->count = 0;
        curr->checksum = BOOTCOUNT_MAGIC;

        ret = pwrite(fd, curr, 16, i * 16);
        if (ret < 0)
                fprintf(stderr, "failed to write: %i\n", ret);
        sync();
out:
        close(fd);

        return 0;
}