[RFC][PATCH] mtd: bcm47part driver for BCM47XX chipsets
Rafał Miłecki
zajec5 at gmail.com
Fri Aug 24 18:30:12 EDT 2012
This driver provides parser detecting partitions on BCM47XX flash
memories. It has many differences in comparision to older BCM63XX, like:
1) Different CFE with no more trivial MAGICs
2) More partitions types (board_data, ML, POT)
3) Supporting more than 1 flash on a device
which resulted in decision of writing new parser.
It uses generic mtd interface and was successfully tested with Netgear
WNDR4500 router which has 2 flash memories: serial one and NAND one.
---
Example of scanning (from my WNDR4500):
[ 3.144000] Creating 3 MTD partitions on "bcm47sflash":
[ 3.148000] 0x000000000000-0x0000001e0000 : "boot"
[ 3.156000] 0x0000001e0000-0x0000001f0000 : "board_data"
[ 3.164000] 0x0000001f0000-0x000000200000 : "nvram"
[ 4.632000] Creating 2 MTD partitions on "NAND 128MiB 3,3V 8-bit":
[ 4.636000] 0x00000000001c-0x0000001416a4 : "linux"
[ 4.644000] 0x0000001416a4-0x0000007ba000 : "rootfs"
Right now there aren't any mainline MTD devices driver using this
parser. It was tested with out-of-tree drivers floating around (for
example on linux-wireless mailing list).
As this driver uses generic mtd interface, it should be safe to include
it in kernel without breaking anything in the future.
TODO:
1) Add support for more partitinos (ML and POT)
2) Optimize: don't scan whole flash (like up to 128 MiB)
3) Optimize: don't scan TRX partitions after detecting header
---
drivers/mtd/Kconfig | 4 +
drivers/mtd/Makefile | 1 +
drivers/mtd/bcm47part.c | 154 +++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 159 insertions(+), 0 deletions(-)
create mode 100644 drivers/mtd/bcm47part.c
diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
index 27143e0..0cd4096 100644
--- a/drivers/mtd/Kconfig
+++ b/drivers/mtd/Kconfig
@@ -148,6 +148,10 @@ config MTD_BCM63XX_PARTS
This provides partions parsing for BCM63xx devices with CFE
bootloaders.
+config MTD_BCM47_PARTS
+ tristate "BCM47XX partitioning support"
+ depends on BCM47XX
+
comment "User Modules And Translation Layers"
config MTD_CHAR
diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile
index f901354..dac90e6 100644
--- a/drivers/mtd/Makefile
+++ b/drivers/mtd/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_MTD_CMDLINE_PARTS) += cmdlinepart.o
obj-$(CONFIG_MTD_AFS_PARTS) += afs.o
obj-$(CONFIG_MTD_AR7_PARTS) += ar7part.o
obj-$(CONFIG_MTD_BCM63XX_PARTS) += bcm63xxpart.o
+obj-$(CONFIG_MTD_BCM47_PARTS) += bcm47part.o
# 'Users' - code which presents functionality to userspace.
obj-$(CONFIG_MTD_CHAR) += mtdchar.o
diff --git a/drivers/mtd/bcm47part.c b/drivers/mtd/bcm47part.c
new file mode 100644
index 0000000..cb06c52
--- /dev/null
+++ b/drivers/mtd/bcm47part.c
@@ -0,0 +1,154 @@
+/*
+ * BCM47XX MTD partitioning
+ *
+ * Copyright (C) 2012 Rafał Miłecki <zajec5 at gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <asm/mach-bcm47xx/nvram.h>
+
+#define BCM47PART_MAX_PARTS 12
+
+/* 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 BCM47PART_BYTES_TO_READ 0x401
+
+#define TRX_MAGIC 0x30524448
+
+struct trx_header {
+ u32 magic;
+ u32 length;
+ u32 crc32;
+ u16 flags;
+ u16 version;
+ u32 offset[3];
+} __packed;
+
+static int bcm47part_parse(struct mtd_info *master,
+ struct mtd_partition **pparts,
+ struct mtd_part_parser_data *data)
+{
+ struct mtd_partition *parts;
+ u8 i, curr_part = 0;
+ u8 *buf;
+ u32 *fourcc;
+ size_t bytes_read;
+ u32 offset;
+ u32 blocksize = 0x10000;
+ struct trx_header *trx;
+
+ /* Alloc */
+ parts = kzalloc(sizeof(struct mtd_partition) * BCM47PART_MAX_PARTS,
+ GFP_KERNEL);
+ buf = kzalloc(sizeof(*buf) * BCM47PART_BYTES_TO_READ, GFP_KERNEL);
+
+ /* Parse block by block looking for magics */
+ for (offset = 0; offset <= master->size - blocksize;
+ offset += blocksize) {
+ if (mtd_read(master, offset, BCM47PART_BYTES_TO_READ,
+ &bytes_read, buf) < 0) {
+ pr_err("mtd_read error while parsing (offset: 0x%X)!\n",
+ offset);
+ continue;
+ }
+
+ /* CFE has small NVRAM at 0x400 */
+ fourcc = (u32 *)&buf[0x400];
+ if (*fourcc == NVRAM_HEADER) {
+ parts[curr_part].name = "boot";
+ parts[curr_part].mask_flags = MTD_WRITEABLE;
+ parts[curr_part].offset = offset;
+ curr_part++;
+ }
+
+ /* Standard NVRAM */
+ fourcc = (u32 *)&buf[0x000];
+ if (*fourcc == NVRAM_HEADER) {
+ parts[curr_part].name = "nvram";
+ parts[curr_part].mask_flags = MTD_WRITEABLE;
+ parts[curr_part].offset = offset;
+ curr_part++;
+ }
+
+ /* board_data starts with board_id which differs across boards,
+ * but we can use 'MPFR' (hopefully) magic at 0x100 */
+ fourcc = (u32 *)&buf[0x100];
+ if (*fourcc == 0x5246504D) { /* MPFR */
+ parts[curr_part].name = "board_data";
+ parts[curr_part].mask_flags = MTD_WRITEABLE;
+ parts[curr_part].offset = offset;
+ curr_part++;
+ }
+
+ /* TRX */
+ fourcc = (u32 *)&buf[0x000];
+ if (*fourcc == TRX_MAGIC) {
+ trx = (struct trx_header *)buf;
+
+ i = 0;
+ /* We have LZMA loader if offset[2] points to sth */
+ if (trx->offset[2]) {
+ /* TODO: should we add LZMA loader partition? */
+ i++;
+ }
+
+ parts[curr_part].name = "linux";
+ parts[curr_part].mask_flags = MTD_WRITEABLE;
+ parts[curr_part].offset = offset + trx->offset[i];
+ curr_part++;
+ i++;
+
+ parts[curr_part].name = "rootfs";
+ parts[curr_part].mask_flags = MTD_WRITEABLE;
+ parts[curr_part].offset = offset + trx->offset[i];
+ parts[curr_part].size = trx->length - trx->offset[i];
+ curr_part++;
+ i++;
+ }
+ }
+
+ /* We can't read sizes of some (most of) partitions. Assume that
+ * these partitions end at the beginning of the one they are
+ * followed by. */
+ for (i = 0; i < curr_part - 1; i++) {
+ if (parts[i].size == 0)
+ parts[i].size = parts[i + 1].offset - parts[i].offset;
+ }
+ if (curr_part > 0 && parts[curr_part - 1].size == 0)
+ parts[curr_part - 1].size =
+ master->size - parts[curr_part - 1].offset;
+
+ *pparts = parts;
+ return curr_part;
+};
+
+static struct mtd_part_parser bcm47part_mtd_parser = {
+ .owner = THIS_MODULE,
+ .parse_fn = bcm47part_parse,
+ .name = "bcm47part",
+};
+
+static int __init bcm47part_init(void)
+{
+ return register_mtd_parser(&bcm47part_mtd_parser);
+}
+
+static void __exit bcm47part_exit(void)
+{
+ deregister_mtd_parser(&bcm47part_mtd_parser);
+}
+
+module_init(bcm47part_init);
+module_exit(bcm47part_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MTD partitioning for BCM47XX flash memories");
--
1.7.7
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