/*
 * Copyright (c) 2013, Sergey 'Jin' Bostandzhyan
 *
 * Licensed 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.
 */

/* This is a hack for Rockchip rk3x based devices. The problem is that
 * the MEMERASE ioctl is failing (hangs and never returns) in their kernel.
 * The sources are not fully available, so fixing it in the rk30xxnand_ko driver
 * is not possible.
 *
 * I straced the stock recovery application and it seems to avoid this
 * particular ioctl, instead it is simply writing zeroes using the write() call.
 *
 * This workaround does the same and will replace all MEMERASE occurances in
 * the recovery code.
 */

#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>

#include "rk3xhack.h"

int rk30_zero_out(int fd, off_t pos, ssize_t size)
{
    if (lseek(fd, pos, SEEK_SET) != pos) {
        fprintf(stderr, "mtd: erase failure at 0x%08lx (%s)\n",
                pos, strerror(errno));
        return -1;
    }

    unsigned char *zb = (unsigned char *)calloc(1, size);
    if (zb == NULL) {
        fprintf(stderr, "mtd: erase failure, could not allocate memory\n");
        return -1;
    }

    if (write(fd, zb, size) != size) {
        fprintf(stderr, "mtd: erase failure at 0x%08lx (%s)\n",
                pos, strerror(errno));
        free(zb);
        return -1;
    }

    free(zb);
    return 0;
}