73 lines
2.9 KiB
C
73 lines
2.9 KiB
C
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/***************************************************************************
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* __________ __ ___.
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* Open \______ \ ____ ____ | | _\_ |__ _______ ___
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* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
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* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
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* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
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* \/ \/ \/ \/ \/
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* $Id$
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*
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* Copyright (C) 2012 by Amaury Pouly
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
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* KIND, either express or implied.
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*
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****************************************************************************/
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#include "partitions-imx233.h"
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static bool enable_window = true;
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void imx233_partitions_enable_window(bool enable)
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{
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enable_window = enable;
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}
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bool imx233_partitions_is_window_enabled(void)
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{
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return enable_window;
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}
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int imx233_partitions_compute_window(uint8_t mbr[512], unsigned *start, unsigned *end)
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{
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/**
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* Freescale uses a strange layout: is has a first MBR at sector 0 with four entries:
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* 1) Actual user partition
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* 2) Sigmatel boot partition
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* 3)4) Other (certificate related ?) partitions
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* The partition 1) has type 1 but it's actually a type 5 (logical partition) with
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* a second partition table with usually one entry which is the FAT32 one.
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* The first table uses 512-byte sector size and the second one usually uses
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* 2048-byte logical sector size.
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*
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* We restrict the window to the user partition
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*
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* WARNING HACK FIXME BUG
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* Reverse engineering and experiments suggests that the OF ignores the lowest 2 bits
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* of the LBAs in the partition table. There is at least one example
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* (the Creative Zen X-Fi3) where this is important because the LBA of the user partition
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* is not a multiple of 4. The behaviour of the size field is less clear but
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* it seems that it is similarly truncated. */
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if(mbr[510] != 0x55 || mbr[511] != 0xAA)
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return -101; /* invalid MBR */
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/* sanity check that the first partition is greater than 2Gib */
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uint8_t *ent = &mbr[446];
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*start = ent[8] | ent[9] << 8 | ent[10] << 16 | ent[11] << 24;
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/* ignore two lowest bits(see comment above) */
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*start &= ~3;
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*end = (ent[12] | ent[13] << 8 | ent[14] << 16 | ent[15] << 24);
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*end &= ~3;
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/* ignore two lowest bits(order is important, first truncate then add start) */
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*end += *start;
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if(ent[4] == 0x53)
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return -102; /* sigmatel partition */
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if((*end - *start) < 4 * 1024 * 1024)
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return -103; /* partition too small */
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return 0;
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}
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