318 lines
8.7 KiB
C
318 lines
8.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* BCM47XX MTD partitioning
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*
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* Copyright © 2012 Rafał Miłecki <zajec5@gmail.com>
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*/
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#include <linux/bcm47xx_nvram.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/partitions.h>
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#include <uapi/linux/magic.h>
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/*
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* NAND flash on Netgear R6250 was verified to contain 15 partitions.
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* This will result in allocating too big array for some old devices, but the
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* memory will be freed soon anyway (see mtd_device_parse_register).
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*/
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#define BCM47XXPART_MAX_PARTS 20
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/*
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* Amount of bytes we read when analyzing each block of flash memory.
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* Set it big enough to allow detecting partition and reading important data.
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*/
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#define BCM47XXPART_BYTES_TO_READ 0x4e8
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/* Magics */
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#define BOARD_DATA_MAGIC 0x5246504D /* MPFR */
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#define BOARD_DATA_MAGIC2 0xBD0D0BBD
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#define CFE_MAGIC 0x43464531 /* 1EFC */
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#define FACTORY_MAGIC 0x59544346 /* FCTY */
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#define NVRAM_HEADER 0x48534C46 /* FLSH */
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#define POT_MAGIC1 0x54544f50 /* POTT */
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#define POT_MAGIC2 0x504f /* OP */
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#define ML_MAGIC1 0x39685a42
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#define ML_MAGIC2 0x26594131
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#define TRX_MAGIC 0x30524448
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#define SHSQ_MAGIC 0x71736873 /* shsq (weird ZTE H218N endianness) */
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static const char * const trx_types[] = { "trx", NULL };
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struct trx_header {
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uint32_t magic;
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uint32_t length;
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uint32_t crc32;
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uint16_t flags;
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uint16_t version;
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uint32_t offset[3];
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} __packed;
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static void bcm47xxpart_add_part(struct mtd_partition *part, const char *name,
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u64 offset, uint32_t mask_flags)
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{
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part->name = name;
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part->offset = offset;
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part->mask_flags = mask_flags;
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}
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/**
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* bcm47xxpart_bootpartition - gets index of TRX partition used by bootloader
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*
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* Some devices may have more than one TRX partition. In such case one of them
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* is the main one and another a failsafe one. Bootloader may fallback to the
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* failsafe firmware if it detects corruption of the main image.
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*
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* This function provides info about currently used TRX partition. It's the one
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* containing kernel started by the bootloader.
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*/
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static int bcm47xxpart_bootpartition(void)
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{
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char buf[4];
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int bootpartition;
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/* Check CFE environment variable */
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if (bcm47xx_nvram_getenv("bootpartition", buf, sizeof(buf)) > 0) {
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if (!kstrtoint(buf, 0, &bootpartition))
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return bootpartition;
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}
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return 0;
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}
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static int bcm47xxpart_parse(struct mtd_info *master,
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const struct mtd_partition **pparts,
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struct mtd_part_parser_data *data)
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{
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struct mtd_partition *parts;
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uint8_t i, curr_part = 0;
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uint32_t *buf;
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size_t bytes_read;
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uint32_t offset;
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uint32_t blocksize = master->erasesize;
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int trx_parts[2]; /* Array with indexes of TRX partitions */
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int trx_num = 0; /* Number of found TRX partitions */
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int possible_nvram_sizes[] = { 0x8000, 0xF000, 0x10000, };
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int err;
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/*
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* Some really old flashes (like AT45DB*) had smaller erasesize-s, but
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* partitions were aligned to at least 0x1000 anyway.
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*/
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if (blocksize < 0x1000)
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blocksize = 0x1000;
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/* Alloc */
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parts = kcalloc(BCM47XXPART_MAX_PARTS, sizeof(struct mtd_partition),
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GFP_KERNEL);
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if (!parts)
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return -ENOMEM;
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buf = kzalloc(BCM47XXPART_BYTES_TO_READ, GFP_KERNEL);
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if (!buf) {
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kfree(parts);
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return -ENOMEM;
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}
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/* Parse block by block looking for magics */
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for (offset = 0; offset <= master->size - blocksize;
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offset += blocksize) {
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/* Nothing more in higher memory on BCM47XX (MIPS) */
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if (IS_ENABLED(CONFIG_BCM47XX) && offset >= 0x2000000)
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break;
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if (curr_part >= BCM47XXPART_MAX_PARTS) {
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pr_warn("Reached maximum number of partitions, scanning stopped!\n");
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break;
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}
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/* Read beginning of the block */
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err = mtd_read(master, offset, BCM47XXPART_BYTES_TO_READ,
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&bytes_read, (uint8_t *)buf);
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if (err && !mtd_is_bitflip(err)) {
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pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
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offset, err);
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continue;
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}
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/* Magic or small NVRAM at 0x400 */
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if ((buf[0x4e0 / 4] == CFE_MAGIC && buf[0x4e4 / 4] == CFE_MAGIC) ||
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(buf[0x400 / 4] == NVRAM_HEADER)) {
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bcm47xxpart_add_part(&parts[curr_part++], "boot",
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offset, MTD_WRITEABLE);
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continue;
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}
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/*
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* board_data starts with board_id which differs across boards,
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* but we can use 'MPFR' (hopefully) magic at 0x100
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*/
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if (buf[0x100 / 4] == BOARD_DATA_MAGIC) {
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bcm47xxpart_add_part(&parts[curr_part++], "board_data",
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offset, MTD_WRITEABLE);
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continue;
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}
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/* Found on Huawei E970 */
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if (buf[0x000 / 4] == FACTORY_MAGIC) {
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bcm47xxpart_add_part(&parts[curr_part++], "factory",
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offset, MTD_WRITEABLE);
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continue;
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}
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/* POT(TOP) */
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if (buf[0x000 / 4] == POT_MAGIC1 &&
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(buf[0x004 / 4] & 0xFFFF) == POT_MAGIC2) {
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bcm47xxpart_add_part(&parts[curr_part++], "POT", offset,
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MTD_WRITEABLE);
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continue;
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}
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/* ML */
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if (buf[0x010 / 4] == ML_MAGIC1 &&
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buf[0x014 / 4] == ML_MAGIC2) {
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bcm47xxpart_add_part(&parts[curr_part++], "ML", offset,
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MTD_WRITEABLE);
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continue;
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}
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/* TRX */
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if (buf[0x000 / 4] == TRX_MAGIC) {
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struct trx_header *trx;
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uint32_t last_subpart;
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uint32_t trx_size;
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if (trx_num >= ARRAY_SIZE(trx_parts))
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pr_warn("No enough space to store another TRX found at 0x%X\n",
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offset);
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else
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trx_parts[trx_num++] = curr_part;
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bcm47xxpart_add_part(&parts[curr_part++], "firmware",
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offset, 0);
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/*
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* Try to find TRX size. The "length" field isn't fully
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* reliable as it could be decreased to make CRC32 cover
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* only part of TRX data. It's commonly used as checksum
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* can't cover e.g. ever-changing rootfs partition.
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* Use offsets as helpers for assuming min TRX size.
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*/
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trx = (struct trx_header *)buf;
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last_subpart = max3(trx->offset[0], trx->offset[1],
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trx->offset[2]);
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trx_size = max(trx->length, last_subpart + blocksize);
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/*
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* Skip the TRX data. Decrease offset by block size as
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* the next loop iteration will increase it.
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*/
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offset += roundup(trx_size, blocksize) - blocksize;
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continue;
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}
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/* Squashfs on devices not using TRX */
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if (le32_to_cpu(buf[0x000 / 4]) == SQUASHFS_MAGIC ||
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buf[0x000 / 4] == SHSQ_MAGIC) {
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bcm47xxpart_add_part(&parts[curr_part++], "rootfs",
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offset, 0);
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continue;
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}
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/*
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* New (ARM?) devices may have NVRAM in some middle block. Last
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* block will be checked later, so skip it.
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*/
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if (offset != master->size - blocksize &&
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buf[0x000 / 4] == NVRAM_HEADER) {
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bcm47xxpart_add_part(&parts[curr_part++], "nvram",
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offset, 0);
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continue;
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}
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/* Read middle of the block */
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err = mtd_read(master, offset + (blocksize / 2), 0x4, &bytes_read,
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(uint8_t *)buf);
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if (err && !mtd_is_bitflip(err)) {
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pr_err("mtd_read error while parsing (offset: 0x%X): %d\n",
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offset + (blocksize / 2), err);
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continue;
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}
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/* Some devices (ex. WNDR3700v3) don't have a standard 'MPFR' */
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if (buf[0x000 / 4] == BOARD_DATA_MAGIC2) {
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bcm47xxpart_add_part(&parts[curr_part++], "board_data",
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offset, MTD_WRITEABLE);
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continue;
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}
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}
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/* Look for NVRAM at the end of the last block. */
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for (i = 0; i < ARRAY_SIZE(possible_nvram_sizes); i++) {
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if (curr_part >= BCM47XXPART_MAX_PARTS) {
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pr_warn("Reached maximum number of partitions, scanning stopped!\n");
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break;
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}
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offset = master->size - possible_nvram_sizes[i];
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err = mtd_read(master, offset, 0x4, &bytes_read,
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(uint8_t *)buf);
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if (err && !mtd_is_bitflip(err)) {
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pr_err("mtd_read error while reading (offset 0x%X): %d\n",
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offset, err);
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continue;
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}
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/* Standard NVRAM */
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if (buf[0] == NVRAM_HEADER) {
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bcm47xxpart_add_part(&parts[curr_part++], "nvram",
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master->size - blocksize, 0);
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break;
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}
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}
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kfree(buf);
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/*
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* Assume that partitions end at the beginning of the one they are
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* followed by.
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*/
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for (i = 0; i < curr_part; i++) {
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u64 next_part_offset = (i < curr_part - 1) ?
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parts[i + 1].offset : master->size;
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parts[i].size = next_part_offset - parts[i].offset;
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}
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/* If there was TRX parse it now */
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for (i = 0; i < trx_num; i++) {
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struct mtd_partition *trx = &parts[trx_parts[i]];
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if (i == bcm47xxpart_bootpartition())
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trx->types = trx_types;
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else
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trx->name = "failsafe";
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}
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*pparts = parts;
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return curr_part;
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};
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static const struct of_device_id bcm47xxpart_of_match_table[] = {
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{ .compatible = "brcm,bcm947xx-cfe-partitions" },
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{},
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};
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MODULE_DEVICE_TABLE(of, bcm47xxpart_of_match_table);
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static struct mtd_part_parser bcm47xxpart_mtd_parser = {
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.parse_fn = bcm47xxpart_parse,
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.name = "bcm47xxpart",
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.of_match_table = bcm47xxpart_of_match_table,
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};
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module_mtd_part_parser(bcm47xxpart_mtd_parser);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");
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