Re: [PATCH v6] mtd: sharpslpart: Add sharpslpart partition parser

From: Boris Brezillon
Date: Tue Aug 22 2017 - 08:54:44 EST

Hi Andrea,

Le Tue, 22 Aug 2017 11:42:52 +0200,
Andrea Adami <andrea.adami@xxxxxxxxx> a Ãcrit :

> 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@xxxxxxxxx>
> ---

Please put a changelog here.

> drivers/mtd/parsers/Kconfig | 7 +
> drivers/mtd/parsers/Makefile | 1 +
> drivers/mtd/parsers/sharpslpart.c | 382 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 390 insertions(+)
> create mode 100644 drivers/mtd/parsers/sharpslpart.c
>
> diff --git a/drivers/mtd/parsers/Kconfig b/drivers/mtd/parsers/Kconfig
> index d206b3c..f371022 100644
> --- a/drivers/mtd/parsers/Kconfig
> +++ b/drivers/mtd/parsers/Kconfig
> @@ -6,3 +6,10 @@ config MTD_PARSER_TRX
> may contain up to 3/4 partitions (depending on the version).
> This driver will parse TRX header and report at least two partitions:
> kernel and rootfs.

Missing blank line.

> +config MTD_SHARPSL_PARTS
> + tristate "Sharp SL Series NAND flash partition parser"
> + depends on MTD_NAND_SHARPSL || MTD_NAND_TMIO || 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.
> diff --git a/drivers/mtd/parsers/Makefile b/drivers/mtd/parsers/Makefile
> index 4d9024e..5b1bcc3 100644
> --- a/drivers/mtd/parsers/Makefile
> +++ b/drivers/mtd/parsers/Makefile
> @@ -1 +1,2 @@
> obj-$(CONFIG_MTD_PARSER_TRX) += parser_trx.o
> +obj-$(CONFIG_MTD_SHARPSL_PARTS) += sharpslpart.o
> diff --git a/drivers/mtd/parsers/sharpslpart.c b/drivers/mtd/parsers/sharpslpart.c
> new file mode 100644
> index 0000000..b2333ae
> --- /dev/null
> +++ b/drivers/mtd/parsers/sharpslpart.c
> @@ -0,0 +1,382 @@
> +/*
> + * sharpslpart.c - MTD partition parser for NAND flash using the SHARP FTL
> + * for logical addressing, as used on the PXA models of the SHARP SL Series.
> + *
> + * Copyright (C) 2017 Andrea Adami <andrea.adami@xxxxxxxxx>
> + *
> + * Based on 2.4 sources:
> + * drivers/mtd/nand/sharp_sl_logical.c
> + * 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.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/partitions.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
> +
> +#define BLOCK_IS_RESERVED 0xffff
> +#define BLOCK_UNMASK 0x07fe
> +#define BLOCK_UNMASK_COMPLEMENT 1
> +
> +/* factory defaults */
> +#define SHARPSL_NAND_PARTS 3
> +#define SHARPSL_FTL_PART_SIZE (7 * 1024 * 1024)

Nit: s/7 * 1024 * 1024/7 * SZ_1M/

> +#define PARAM_BLOCK_PARTITIONINFO1 0x00060000
> +#define PARAM_BLOCK_PARTITIONINFO2 0x00064000

I'd rename the macro differently. The term block is a bit confusing
here since AFAIU the Param Area does not necessarily fit in a single
eraseblock.

How about:

#define PARAM_AREA_PARTINFO1_LADDR 0x60000
#define PARAM_AREA_PARTINFO2_LADDR 0x64000

or simply

#define SHARPSL_PARTINFO1_LADDR 0x60000
#define SHARPSL_PARTINFO2_LADDR 0x64000

> +
> +#define BOOT_MAGIC 0x424f4f54
> +#define FSRO_MAGIC 0x4653524f
> +#define FSRW_MAGIC 0x46535257
> +
> +/**
> + * struct sharpsl_ftl - Sharp FTL Logical Table
> + * @logmax: number of logical blocks
> + * @log2phy: the logical-to-physical table
> + *
> + * Stripped down from 2.4 sources for read-only purposes.

Not sure this information is really useful, especially since you don't
provide a link to the 2.4 sources (or maybe I missed it).

You'd better describe what this struct is used for here.

> + */
> +struct sharpsl_ftl {
> + u_int logmax;
> + u_int *log2phy;

Can you replace u_int by unsigned int and u_char by u8? That goes for
the whole file.

> +};
> +
> +static int sharpsl_nand_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,

AFAICT, len is always set to mtd->oobsize. You can just drop this
parameter and set ops->ooblen to mtd->oobsize.

> + uint8_t *buf)
> +{
> + loff_t mask = mtd->writesize - 1;

mask is equivalent to mtd->writesize_mask.

> + struct mtd_oob_ops ops;

struct mtd_oob_ops ops = { };

so that you don't have to initialize all fields if they are set to 0 or
NULL.

You could also directly fill this object when declaring it:

struct mtd_oob_ops ops = {
.mode = MTD_OPS_PLACE_OOB,
.ooblen = mtd->oobsize,
.oobbuf = buf,
};

> + int ret;
> +
> + ops.mode = MTD_OPS_PLACE_OOB;
> + ops.ooboffs = offs & mask;

Hm, I'm pretty sure this is wrong. mask is a page mask, not the oob
area mask. It works because offs is always aligned on a page, but you
can directly assign ops.ooboffs to 0 and you should be good.

> + 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;
> +}
> +
> +/*
> + * The logical block number assigned to a physical block is stored in the OOB
> + * of the first page, in 3 16-bit copies with the following layout:
> + *
> + * 01234567 89abcdef
> + * -------- --------
> + * ECC BB xyxyxy
> + *
> + * When reading we check that the first two copies agree.
> + * In case of error, matching is tried using the following pairs.
> + * Reserved values 0xffff mean the block is kept for wear leveling.
> + *
> + * 01234567 89abcdef
> + * -------- --------
> + * ECC BB xyxy oob[8]==oob[10] && oob[9]==oob[11] -> byte0=8 byte1=9
> + * ECC BB xyxy oob[10]==oob[12] && oob[11]==oob[13] -> byte0=10 byte1=11
> + * ECC BB xy xy oob[12]==oob[8] && oob[13]==oob[9] -> byte0=12 byte1=13
> + *
> + */
> +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 {
> + /* wrong oob fingerprint, maybe here by mistake? */
> + return UINT_MAX;
> + }
> +
> + us = oob[good0] | oob[good1] << 8;
> +
> + /* parity check */
> + if (hweight16(us) & BLOCK_UNMASK_COMPLEMENT)
> + return (UINT_MAX - 1);

Why not making this function return an int and use regular error codes
for the parity and wrong fingerprint errors?

> +
> + /* reserved */
> + if (us == BLOCK_IS_RESERVED)
> + return BLOCK_IS_RESERVED;
> + else

You can drop the 'else' here.

> + return (us & BLOCK_UNMASK) >> 1;

So, this is a 10bit value, right? Why not doing the >> 1 first so that
your BLOCK_UNMASK mask really looks like a valid mask (0x3ff, which can
also be defined as GENMASK(9, 0)).

> +}
> +
> +static int sharpsl_nand_init_logical(struct mtd_info *mtd, u32 partition_size,

s/sharpsl_nand_init_logical/sharpsl_nand_init_ftl/

partition_size is always set to SHARPSL_FTL_PART_SIZE. Please drop this
argument.

> + struct sharpsl_ftl *ftl)
> +{
> + u_int block_num, log_num, phymax;
> + loff_t block_adr;
> + u_char *oob;
> + int i, ret;
> +
> + oob = kzalloc(mtd->oobsize, GFP_KERNEL);
> + if (!oob)
> + return -ENOMEM;
> +
> + /* initialize management structure */
> + phymax = (partition_size / mtd->erasesize);

You can use mtd_div_by_eb() here.

> +
> + /* FTL reserves 5% of the blocks + 1 spare */
> + ftl->logmax = ((phymax * 95) / 100) - 1;
> +
> + ftl->log2phy = kmalloc_array(ftl->logmax, sizeof(u_int),

sizeof(*ftl->log2phy)

> + GFP_KERNEL);
> + if (!ftl->log2phy) {
> + ret = -ENOMEM;
> + goto exit;
> + }
> +
> + /* initialize ftl->log2phy */
> + for (i = 0; i < ftl->logmax; i++)
> + ftl->log2phy[i] = UINT_MAX;
> +
> + /* create physical-logical table */
> + for (block_num = 0; block_num < phymax; block_num++) {
> + block_adr = block_num * mtd->erasesize;
> +
> + if (mtd_block_isbad(mtd, block_adr))
> + continue;
> +
> + if (sharpsl_nand_read_oob(mtd, block_adr, mtd->oobsize, oob))
> + continue;
> +
> + /* get logical block */
> + log_num = sharpsl_nand_get_logical_num(oob);
> +
> + /* FTL is not used? Exit here if the oob fingerprint is wrong */
> + if (log_num == UINT_MAX) {
> + pr_info("sharpslpart: Sharp SL FTL not found.\n");
> + ret = -EINVAL;
> + goto exit;
> + }
> +
> + /* skip out of range and not unique values */
> + if (log_num < ftl->logmax) {
> + if (ftl->log2phy[log_num] == UINT_MAX)
> + ftl->log2phy[log_num] = block_num;
> + }
> + }
> +
> + pr_info("Sharp SL FTL: %d blocks used (%d logical, %d reserved)\n",
> + phymax, ftl->logmax,
> + phymax - ftl->logmax);
> +
> + ret = 0;
> +exit:
> + kfree(oob);
> + return ret;
> +}
> +
> +void sharpsl_nand_cleanup_logical(struct sharpsl_ftl *ftl)

s/sharpsl_nand_cleanup_logical/sharpsl_nand_cleanup_ftl/

> +{
> + kfree(ftl->log2phy);
> +}
> +
> +static int sharpsl_nand_read_laddr(struct mtd_info *mtd,
> + loff_t from,
> + size_t len,
> + u_char *buf,
> + struct sharpsl_ftl *ftl)
> +{
> + u_int log_num, log_new;
> + u_int block_num;
> + loff_t block_adr;
> + loff_t block_ofs;
> + size_t retlen;
> + int err;
> +
> + log_num = (u32)from / mtd->erasesize;

Please use mtd_div_by_eb().

> + log_new = ((u32)from + len - 1) / mtd->erasesize;

Ditto.

And I'm not sure log_new is a good name for this variable. Could be
last_log_num or something like that.

> +
> + if (len <= 0 || log_num >= ftl->logmax || log_new > log_num)
> + return -EINVAL;
> +
> + block_num = ftl->log2phy[log_num];
> + block_adr = block_num * mtd->erasesize;
> + block_ofs = (u32)from % mtd->erasesize;

mtd_mod_by_eb().

> +
> + err = mtd_read(mtd, block_adr + block_ofs, len, &retlen, buf);
> + /* Ignore corrected ECC errors */
> + if (mtd_is_bitflip(err))
> + err = 0;

Please add a blank line here

> + if (!err && retlen != len)
> + err = -EIO;

and here.

> + if (err)
> + pr_err("sharpslpart: error, read failed at %#llx\n",
> + block_adr + block_ofs);
> +
> + return err;
> +}
> +
> +/*
> + * MTD Partition Parser
> + *
> + * 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 ................
> + *

You can drop this extra empty line.

> + */
> +struct sharpsl_nand_partinfo {
> + __le32 start;
> + __le32 end;
> + __be32 magic;
> + u32 reserved;
> +};
> +
> +static int sharpsl_nand_read_partinfo(struct mtd_info *master,
> + loff_t from,
> + size_t len,
> + struct sharpsl_nand_partinfo *buf,
> + struct sharpsl_ftl *ftl)
> +{
> + int ret;
> +
> + ret = sharpsl_nand_read_laddr(master, (u32)from, len, (u_char *)buf,

The u32 cast is unneeded here, and I'd suggest to change the
sharpsl_nand_read_laddr() prototype to take a 'void *' instead of a
'u_char *', so that you can also get rid of this cast.

> + ftl);
> + if (ret)
> + goto exit;

Well, you have nothing to cleanup in the exit path, so you can return
directly here.

> +
> + /* check for magics */
> + if (be32_to_cpu(buf[0].magic) != BOOT_MAGIC ||
> + be32_to_cpu(buf[1].magic) != FSRO_MAGIC ||
> + be32_to_cpu(buf[2].magic) != FSRW_MAGIC) {
> + pr_err("sharpslpart: magic values mismatch\n");
> + ret = -EINVAL;
> + goto exit;

Ditto.

> + }
> +
> + /* fixup for hardcoded value 64 MiB (for older models) */
> + buf[2].end = cpu_to_le32(master->size);
> +
> + /* extra sanity check */
> + if (le32_to_cpu(buf[0].end) <= le32_to_cpu(buf[0].start) ||
> + le32_to_cpu(buf[1].start) < le32_to_cpu(buf[0].end) ||
> + le32_to_cpu(buf[1].end) <= le32_to_cpu(buf[1].start) ||
> + le32_to_cpu(buf[2].start) < le32_to_cpu(buf[1].end) ||
> + le32_to_cpu(buf[2].end) <= le32_to_cpu(buf[2].start)) {
> + pr_err("sharpslpart: partition sizes mismatch\n");
> + ret = -EINVAL;
> + goto exit;

Ditto.

> + }
> +
> + ret = 0;
> +exit:
> + return ret;
> +}
> +
> +static int sharpsl_parse_mtd_partitions(struct mtd_info *master,
> + const struct mtd_partition **pparts,
> + struct mtd_part_parser_data *data)
> +{
> + struct sharpsl_ftl ftl;
> + struct sharpsl_nand_partinfo buf[SHARPSL_NAND_PARTS];
> + struct mtd_partition *sharpsl_nand_parts;
> + int err, ret;
> +
> + /* init logical mgmt (FTL) */
> + err = sharpsl_nand_init_logical(master, SHARPSL_FTL_PART_SIZE, &ftl);
> + if (err)
> + return err;
> +
> + /* read and validate first partition table */
> + pr_info("sharpslpart: using first partition table\n");
> + err = sharpsl_nand_read_partinfo(master,
> + PARAM_BLOCK_PARTITIONINFO1,
> + sizeof(buf), buf, &ftl);
> + if (err) {
> + /* fallback: read second partition table */
> + pr_warn("sharpslpart: retry using second partition table\n");
> + ret = sharpsl_nand_read_partinfo(master,
> + PARAM_BLOCK_PARTITIONINFO2,
> + sizeof(buf), buf, &ftl);

Why do you need a different variable to store the second
sharpsl_nand_read_partinfo() return code?

> + if (ret) {
> + pr_err("sharpslpart: partition tables are invalid\n");
> + sharpsl_nand_cleanup_logical(&ftl);
> + return ret;
> + }
> + }
> +
> + /* cleanup logical mgmt (FTL) */
> + sharpsl_nand_cleanup_logical(&ftl);


How about:

pr_info("sharpslpart: try reading first partition table\n");
err = sharpsl_nand_read_partinfo(master,
PARAM_BLOCK_PARTITIONINFO1,
sizeof(buf), buf, &ftl);
if (err) {
/* fallback: read second partition table */
pr_warn("sharpslpart: first partition table is invalid, retry using second partition table\n");
err = sharpsl_nand_read_partinfo(master,
PARAM_BLOCK_PARTITIONINFO2,
sizeof(buf), buf, &ftl);
}

/* cleanup logical mgmt (FTL) */
sharpsl_nand_cleanup_logical(&ftl);

if (err) {
pr_err("sharpslpart: both partition tables are invalid\n");
return ret;
}

so that you have a single place where you cleanup the FTL.

> +
> + 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 = le32_to_cpu(buf[0].start);
> + sharpsl_nand_parts[0].size = le32_to_cpu(buf[0].end) -
> + le32_to_cpu(buf[0].start);
> +
> + sharpsl_nand_parts[1].name = "root";
> + sharpsl_nand_parts[1].offset = le32_to_cpu(buf[1].start);
> + sharpsl_nand_parts[1].size = le32_to_cpu(buf[1].end) -
> + le32_to_cpu(buf[1].start);
> +
> + sharpsl_nand_parts[2].name = "home";
> + sharpsl_nand_parts[2].offset = le32_to_cpu(buf[2].start);
> + sharpsl_nand_parts[2].size = le32_to_cpu(buf[2].end) -
> + le32_to_cpu(buf[2].start);
> +
> + *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@xxxxxxxxx>");
> +MODULE_DESCRIPTION("MTD partitioning for NAND flash on Sharp SL Series");