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