Re: [PATCH v3 1/9] mtd: sharpslpart: add sharpslpart MTD partition parser

Brian Norris
2017-06-09T01:30:48Z

Hi,

On Thu, Jun 01, 2017 at 12:40:50AM +0200, Andrea Adami wrote:
> The Sharp SL Series (Zaurus) PXA handhelds have 16/64/128M of NAND flash
> and share the same layout of the first 7M partition, managed by Sharp FTL.
>
> The purpose of this self-contained patch is to add a common parser and
> remove the hardcoded sizes in the board files (these devices are not yet
> converted to devicetree).
> Users will have benefits because the mtdparts= tag will not be necessary
> anymore and they will be free to repartition the little sized flash.
>
> The obsolete bootloader can not pass the partitioning info to modern
> kernels anymore so it has to be read from flash at known logical addresses.
> (see http://www.h5.dion.ne.jp/~rimemoon/zaurus/memo_006.htm )
>
> In kernel, under arch/arm/mach-pxa we have already 8 machines:
> MACH_POODLE, MACH_CORGI, MACH_SHEPERD, MACH_HUSKY, MACH_AKITA, MACH_SPITZ,
> MACH_BORZOI, MACH_TOSA.
> Lost after the 2.4 vendor kernel are MACH_BOXER and MACH_TERRIER.
>
> Almost every model has different factory partitioning: add to this the
> units can be repartitioned by users with userspace tools (nandlogical)
> and installers for popular (back then) linux distributions.
>
> The Parameter Area in the first (boot) partition extends from 0x00040000 to
> 0x0007bfff (176k) and contains two copies of the partition table:
> ...
> 0x00060000: Partition Info1 16k
> 0x00064000: Partition Info2 16k
> 0x00668000: Model 16k
> ...
>
> The first 7M partition is managed by the Sharp FTL reserving 5% + 1 blocks
> for wear-leveling: some blocks are remapped and one layer of translation
> (logical to physical) is necessary.
>
> There isn't much documentation about this FTL in the 2.4 sources, just the
> MTD methods for reading and writing using logical addresses and the block
> management (wear-leveling, use counter).
> For the purpose of the MTD parser only the read part of the code was taken.
>
> The NAND drivers that can use this parser are sharpsl.c and tmio_nand.c.
>
> Signed-off-by: Andrea Adami <andrea.adami@gmail.com>
> ---
> drivers/mtd/Kconfig | 8 ++
> drivers/mtd/Makefile | 2 +
> drivers/mtd/sharpsl_ftl.c | 216 ++++++++++++++++++++++++++++++++++++++++++++++
> drivers/mtd/sharpsl_ftl.h | 34 ++++++++
> drivers/mtd/sharpslpart.c | 132 ++++++++++++++++++++++++++++
> 5 files changed, 392 insertions(+)
> create mode 100644 drivers/mtd/sharpsl_ftl.c
> create mode 100644 drivers/mtd/sharpsl_ftl.h
> create mode 100644 drivers/mtd/sharpslpart.c
>
> diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
> index e83a279..5c96127 100644
> --- a/drivers/mtd/Kconfig
> +++ b/drivers/mtd/Kconfig
> @@ -155,6 +155,14 @@ config MTD_BCM47XX_PARTS
> This provides partitions parser for devices based on BCM47xx
> boards.
>
> +config MTD_SHARPSL_PARTS
> + tristate "Sharp SL Series NAND flash partition parser"
> + depends on MTD_NAND_SHARPSL || MTD_NAND_TMIO

Please include '|| COMPILE_TEST'.

> + help
> + This provides the read-only FTL logic necessary to read the partition
> + table from the NAND flash of Sharp SL Series (Zaurus) and the MTD
> + partition parser using this code.
> +
> comment "User Modules And Translation Layers"
>
> #
> diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile
> index 99bb9a1..89f707b 100644
> --- a/drivers/mtd/Makefile
> +++ b/drivers/mtd/Makefile
> @@ -13,6 +13,8 @@ obj-$(CONFIG_MTD_AFS_PARTS) += afs.o
> obj-$(CONFIG_MTD_AR7_PARTS) += ar7part.o
> obj-$(CONFIG_MTD_BCM63XX_PARTS) += bcm63xxpart.o
> obj-$(CONFIG_MTD_BCM47XX_PARTS) += bcm47xxpart.o
> +obj-$(CONFIG_MTD_SHARPSL_PARTS) += sharpsl-part.o
> +sharpsl-part-objs := sharpsl_ftl.o sharpslpart.o
>
> # 'Users' - code which presents functionality to userspace.
> obj-$(CONFIG_MTD_BLKDEVS) += mtd_blkdevs.o
> diff --git a/drivers/mtd/sharpsl_ftl.c b/drivers/mtd/sharpsl_ftl.c
> new file mode 100644
> index 0000000..1796d03
> --- /dev/null
> +++ b/drivers/mtd/sharpsl_ftl.c
> @@ -0,0 +1,216 @@
> +/*
> + * MTD method for NAND accessing via logical address (SHARP FTL)
> + *
> + * Copyright (C) 2017 Andrea Adami <andrea.adami@gmail.com>
> + *
> + * Based on 2.4 sources: drivers/mtd/nand/sharp_sl_logical.c
> + * Copyright (C) 2002 SHARP
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/partitions.h>
> +#include "sharpsl_ftl.h"
> +
> +/* oob structure */
> +#define NAND_NOOB_LOGADDR_00 8
> +#define NAND_NOOB_LOGADDR_01 9
> +#define NAND_NOOB_LOGADDR_10 10
> +#define NAND_NOOB_LOGADDR_11 11
> +#define NAND_NOOB_LOGADDR_20 12
> +#define NAND_NOOB_LOGADDR_21 13
> +
> +/* Logical Table */
> +struct mtd_logical {
> + u32 size; /* size of the handled partition */
> + int index; /* mtd->index */
> + u_int phymax; /* physical blocks */
> + u_int logmax; /* logical blocks */
> + u_int *log2phy; /* the logical-to-physical table */
> +};
> +
> +static struct mtd_logical *sharpsl_mtd_logical;

Please do not use a static variable like this. References should be
dynamic.

Can the pointer just be passed back to the caller, and passed back to
the cleanup function when finished?

Related: do you foresee this parsing code being useful for anything
besides partitions? If not, then it seems like we should just merge the
"ftl" and "part" files. Not a requirement, but it might be cleaner.

> +
> +static int sharpsl_nand_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,
> + uint8_t *buf)
> +{
> + loff_t mask = mtd->writesize - 1;
> + struct mtd_oob_ops ops;
> + int ret;
> +
> + ops.mode = MTD_OPS_PLACE_OOB;
> + ops.ooboffs = offs & mask;
> + ops.ooblen = len;
> + ops.oobbuf = buf;
> + ops.datbuf = NULL;
> +
> + ret = mtd_read_oob(mtd, offs & ~mask, &ops);
> + if (ret != 0 || len != ops.oobretlen)
> + return -1;
> +
> + return 0;
> +}
> +
> +static u_int sharpsl_nand_get_logical_num(u_char *oob)
> +{
> + u16 us;
> + int good0, good1;
> +
> + if (oob[NAND_NOOB_LOGADDR_00] == oob[NAND_NOOB_LOGADDR_10] &&
> + oob[NAND_NOOB_LOGADDR_01] == oob[NAND_NOOB_LOGADDR_11]) {
> + good0 = NAND_NOOB_LOGADDR_00;
> + good1 = NAND_NOOB_LOGADDR_01;
> + } else if (oob[NAND_NOOB_LOGADDR_10] == oob[NAND_NOOB_LOGADDR_20] &&
> + oob[NAND_NOOB_LOGADDR_11] == oob[NAND_NOOB_LOGADDR_21]) {
> + good0 = NAND_NOOB_LOGADDR_10;
> + good1 = NAND_NOOB_LOGADDR_11;
> + } else if (oob[NAND_NOOB_LOGADDR_20] == oob[NAND_NOOB_LOGADDR_00] &&
> + oob[NAND_NOOB_LOGADDR_21] == oob[NAND_NOOB_LOGADDR_01]) {
> + good0 = NAND_NOOB_LOGADDR_20;
> + good1 = NAND_NOOB_LOGADDR_21;
> + } else {
> + return UINT_MAX;
> + }

These seems like a pretty weird form of error protection. IIUC, there
are just 3 copies of the 2-byte sequence number, and we take the first
pair that matches at least one of the others? Could use a comment above
the if/else block, to explain what the logic is. Or perhaps even some
comments at the top of the file, to roughly describe this FTL.

> +
> + us = oob[good0] | oob[good1] << 8;
> +
> + /* parity check */
> + if (hweight16(us) & 1)
> + return (UINT_MAX - 1);
> +
> + /* reserved */
> + if (us == 0xffff)

Magic number should get a descriptive macro?

> + return 0xffff;

What does this mean? IIUC, this is essentially going to be an
out-of-bounds value that gets ignored, right? Should this just be
'return UINT_MAX'?

> + else
> + return (us & 0x07fe) >> 1;

0x07fe could use a macro definition. (And since it seems complementary,
I guess the 1 in 'hweight16(us) & 1' should also be a macro.)

> +}
> +
> +int sharpsl_nand_init_logical(struct mtd_info *mtd, u32 partition_size)
> +{
> + struct mtd_logical *logical = NULL;

You don't need the NULL initialization.

> + u_int block_num, log_num;
> + loff_t block_adr;
> + u_char *oob = NULL;

Same here.

> + int i, readretry;
> +
> + logical = kzalloc(sizeof(*logical), GFP_KERNEL);
> + if (!logical)
> + return -ENOMEM;
> +
> + oob = kzalloc(mtd->oobsize, GFP_KERNEL);
> + if (!oob) {
> + kfree(logical);
> + return -ENOMEM;
> + }
> +
> + /* initialize management structure */
> + logical->size = partition_size;
> + logical->index = mtd->index;
> + logical->phymax = (partition_size / mtd->erasesize);
> +
> + /* FTL reserves 5% of the blocks + 1 spare */
> + logical->logmax = ((logical->phymax * 95) / 100) - 1;
> +
> + logical->log2phy = NULL;
> + logical->log2phy = kcalloc(logical->logmax, sizeof(u_int), GFP_KERNEL);
> + if (!logical->log2phy) {
> + kfree(logical);
> + kfree(oob);
> + return -ENOMEM;
> + }
> +
> + /* initialize logical->log2phy */
> + for (i = 0; i < logical->logmax; i++)
> + logical->log2phy[i] = UINT_MAX;

The 0-initialized kcalloc() is a little superfluous, since you reinit
here. I guess it's a matter of taste.

> +
> + /* create physical-logical table */
> + for (block_num = 0; block_num < logical->phymax; block_num++) {
> + block_adr = block_num * mtd->erasesize;
> +
> + if (mtd_block_isbad(mtd, block_adr))
> + continue;
> +
> + readretry = 3;
> +read_retry:
> + if (sharpsl_nand_read_oob(mtd, block_adr, mtd->oobsize, oob))
> + continue;
> +
> + /* get logical block */
> + log_num = sharpsl_nand_get_logical_num(oob);
> +
> + /* skip out of range and not unique values */
> + if ((int)log_num >= 0 && (log_num < logical->logmax)) {

Why the (int) cast? You should already be eliminating anything larger
than INT_MAX, because they'll be larger than logmax. You should only
need the second comparison.

> + if (logical->log2phy[log_num] == UINT_MAX)
> + logical->log2phy[log_num] = block_num;
> + } else {
> + readretry--;
> + if (readretry)
> + goto read_retry;

What's the idea on the retries? Is this somehow supposed to make NAND
more reliable? That seems unlikely to work... Although notably, OOB is
often not covered by ECC, so maybe this is a really poor attempt at
making up for that?

> + }
> + }
> + kfree(oob);
> + sharpsl_mtd_logical = logical;
> +
> + pr_info("Sharp SL FTL: %d blocks used (%d logical, %d reserved)\n",
> + logical->phymax, logical->logmax,
> + logical->phymax - logical->logmax);
> +
> + return 0;
> +}
> +
> +void sharpsl_nand_cleanup_logical(void)
> +{
> + struct mtd_logical *logical = sharpsl_mtd_logical;

Please make this take a pointer arg, instead of relying on a static var.

> +
> + sharpsl_mtd_logical = NULL;
> +
> + kfree(logical->log2phy);
> + logical->log2phy = NULL;
> + kfree(logical);
> + logical = NULL;
> +}
> +
> +int sharpsl_nand_read_laddr(struct mtd_info *mtd,
> + loff_t from,
> + size_t len,
> + u_char *buf)
> +{
> + struct mtd_logical *logical;
> + u_int log_num, log_new;
> + u_int block_num;
> + loff_t block_adr;
> + loff_t block_ofs;
> + size_t retlen;
> + int ret;
> +
> + logical = sharpsl_mtd_logical;
> + log_num = (u32)from / mtd->erasesize;
> + log_new = ((u32)from + len - 1) / mtd->erasesize;
> +
> + if (len <= 0 || log_num >= logical->logmax || log_new > log_num)
> + return -EINVAL;
> +
> + block_num = logical->log2phy[log_num];
> + block_adr = block_num * mtd->erasesize;
> + block_ofs = (u32)from % mtd->erasesize;
> +
> + ret = mtd_read(mtd, block_adr + block_ofs, len, &retlen, buf);
> + if (ret != 0 || len != retlen)

What about ret == -EUCLEAN? Do you want to handle corrected bitflips?

> + return -EINVAL;
> +
> + return 0;
> +}
> diff --git a/drivers/mtd/sharpsl_ftl.h b/drivers/mtd/sharpsl_ftl.h
> new file mode 100644
> index 0000000..2880cbe
> --- /dev/null
> +++ b/drivers/mtd/sharpsl_ftl.h
> @@ -0,0 +1,34 @@
> +/*
> + * Header file for NAND accessing via logical address (SHARP FTL)
> + *
> + * Copyright (C) 2017 Andrea Adami <andrea.adami@gmail.com>
> + *
> + * Based on 2.4 sources: linux/include/asm-arm/sharp_nand_logical.h
> + * Copyright (C) 2002 SHARP
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#ifndef __SHARPSL_NAND_LOGICAL_H__
> +#define __SHARPSL_NAND_LOGICAL_H__
> +
> +#include <linux/types.h>
> +#include <linux/mtd/mtd.h>
> +
> +int sharpsl_nand_init_logical(struct mtd_info *mtd, u32 partition_size);
> +
> +void sharpsl_nand_cleanup_logical(void);
> +
> +int sharpsl_nand_read_laddr(struct mtd_info *mtd, loff_t from, size_t len,
> + u_char *buf);
> +
> +#endif
> diff --git a/drivers/mtd/sharpslpart.c b/drivers/mtd/sharpslpart.c
> new file mode 100644
> index 0000000..40aebe9
> --- /dev/null
> +++ b/drivers/mtd/sharpslpart.c
> @@ -0,0 +1,132 @@
> +/*
> + * MTD partition parser for NAND flash on Sharp SL Series
> + *
> + * Copyright (C) 2017 Andrea Adami <andrea.adami@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/partitions.h>
> +#include "sharpsl_ftl.h"
> +
> +/* factory defaults */
> +#define SHARPSL_NAND_PARTS 3
> +#define SHARPSL_FTL_PARTITION_SIZE (7 * 1024 * 1024)
> +#define PARAM_BLOCK_PARTITIONINFO1 0x00060000
> +#define PARAM_BLOCK_PARTITIONINFO2 0x00064000
> +
> +#define BOOT_MAGIC be32_to_cpu(0x424f4f54) /* BOOT */
> +#define FSRO_MAGIC be32_to_cpu(0x4653524f) /* FSRO */
> +#define FSRW_MAGIC be32_to_cpu(0x46535257) /* FSRW */
> +
> +/*
> + * Sample values read from SL-C860
> + *
> + * # cat /proc/mtd
> + * dev: size erasesize name
> + * mtd0: 006d0000 00020000 "Filesystem"
> + * mtd1: 00700000 00004000 "smf"
> + * mtd2: 03500000 00004000 "root"
> + * mtd3: 04400000 00004000 "home"
> + *
> + * PARTITIONINFO1
> + * 0x00060000: 00 00 00 00 00 00 70 00 42 4f 4f 54 00 00 00 00 ......p.BOOT....
> + * 0x00060010: 00 00 70 00 00 00 c0 03 46 53 52 4f 00 00 00 00 ..p.....FSRO....
> + * 0x00060020: 00 00 c0 03 00 00 00 04 46 53 52 57 00 00 00 00 ........FSRW....
> + * 0x00060030: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
> + *
> + */
> +
> +struct sharpsl_nand_partitioninfo {
> + u32 start;
> + u32 end;
> + u32 magic;
> + u32 reserved;
> +};
> +
> +static int sharpsl_parse_mtd_partitions(struct mtd_info *master,
> + const struct mtd_partition **pparts,
> + struct mtd_part_parser_data *data)
> +{
> + struct sharpsl_nand_partitioninfo buf1[SHARPSL_NAND_PARTS];
> + struct sharpsl_nand_partitioninfo buf2[SHARPSL_NAND_PARTS];
> + struct mtd_partition *sharpsl_nand_parts;
> +
> + /* init logical mgmt (FTL) */

Do you have any kind of validation logic, to ensure that this parser
actually matches? What if the flash was erased? Or what if somebody
managed to reformat to some other flash layout?

I suppose for many cases like that, the logical mapping will turn up
with a lot of UINT_MAX entries, and then sharpsl_nand_read_laddr() will
return -EINVAL? It'd be nice if there were some more clear sanity
checks though, if possible. Does this FTL have a header we should be
looking for?

> + if (sharpsl_nand_init_logical(master, SHARPSL_FTL_PARTITION_SIZE))
> + return -EINVAL;
> +
> + /* read the two partition tables */
> + if (sharpsl_nand_read_laddr(master,
> + PARAM_BLOCK_PARTITIONINFO1,
> + sizeof(buf1), (u_char *)&buf1) ||
> + sharpsl_nand_read_laddr(master,
> + PARAM_BLOCK_PARTITIONINFO2,
> + sizeof(buf2), (u_char *)&buf2))
> + return -EINVAL;

You've failed to cleanup in the error case here:
sharpsl_nand_cleanup_logical()

Also, consider passing through the actual error code?

> +
> + /* cleanup logical mgmt (FTL) */
> + sharpsl_nand_cleanup_logical();
> +
> + /* compare the two buffers */
> + if (memcmp(&buf1, &buf2, sizeof(buf1))) {
> + pr_err("sharpslpart: PARTITIONINFO 1,2 differ. Quit parser.\n");
> + return -EINVAL;
> + }
> +
> + /* check for magics (just in the first) */
> + if (buf1[0].magic != BOOT_MAGIC ||
> + buf1[1].magic != FSRO_MAGIC ||
> + buf1[2].magic != FSRW_MAGIC) {
> + pr_err("sharpslpart: magic values mismatch. Quit parser.\n");
> + return -EINVAL;
> + }
> +
> + sharpsl_nand_parts = kzalloc(sizeof(*sharpsl_nand_parts) *
> + SHARPSL_NAND_PARTS, GFP_KERNEL);
> + if (!sharpsl_nand_parts)
> + return -ENOMEM;
> +
> + /* original names */
> + sharpsl_nand_parts[0].name = "smf";
> + sharpsl_nand_parts[0].offset = buf1[0].start;
> + sharpsl_nand_parts[0].size = buf1[0].end - buf1[0].start;

Want to sanity check that 'end > start'?

> + sharpsl_nand_parts[0].mask_flags = 0;

Don't need to zero this out, when you've used kzalloc(). Same comments
apply below.

> +
> + sharpsl_nand_parts[1].name = "root";
> + sharpsl_nand_parts[1].offset = buf1[1].start;
> + sharpsl_nand_parts[1].size = buf1[1].end - buf1[1].start;
> + sharpsl_nand_parts[1].mask_flags = 0;
> +
> + sharpsl_nand_parts[2].name = "home";
> + sharpsl_nand_parts[2].offset = buf1[2].start;
> + /* discard buf1[2].end, was for older models with 64M flash */
> + sharpsl_nand_parts[2].size = master->size - buf1[2].start;
> + sharpsl_nand_parts[2].mask_flags = 0;
> +
> + *pparts = sharpsl_nand_parts;
> + return SHARPSL_NAND_PARTS;
> +}
> +
> +static struct mtd_part_parser sharpsl_mtd_parser = {
> + .parse_fn = sharpsl_parse_mtd_partitions,
> + .name = "sharpslpart",
> +};
> +module_mtd_part_parser(sharpsl_mtd_parser);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Andrea Adami <andrea.adami@gmail.com>");
> +MODULE_DESCRIPTION("MTD partitioning for NAND flash on Sharp SL Series");

Brian