Re: [PATCH v4 1/9] mtd: sharpslpart: add sharpslpart MTD partition parser

From: Brian Norris
Date: Sat Aug 12 2017 - 17:35:18 EST

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Hi Andrea,

I'm sorry this had to wait so long, but then...you didn't actually
address several of my comments from the last time :(

This does look better, but still quite a few smaller notes. Hopefully
next one will be merge-able...

On Wed, Jun 28, 2017 at 10:30:28PM +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@xxxxxxxxx>
> ---
> drivers/mtd/Kconfig | 8 +
> drivers/mtd/Makefile | 1 +
> drivers/mtd/sharpslpart.c | 391 ++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 400 insertions(+)
> create mode 100644 drivers/mtd/sharpslpart.c
>
> diff --git a/drivers/mtd/Kconfig b/drivers/mtd/Kconfig
> index e83a279..b196a69 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 || 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.
> +

This has conflicts now; probably should go in
drivers/mtd/parsers/Kconfig now. We should also probably move the other
parsers there, but that's not your problem.

> comment "User Modules And Translation Layers"
>
> #
> diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile
> index 99bb9a1..e5ef07f 100644
> --- a/drivers/mtd/Makefile
> +++ b/drivers/mtd/Makefile
> @@ -13,6 +13,7 @@ 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) += sharpslpart.o

Also has conflicts now. Might as well move to drivers/mtd/parsers/?

>
> # 'Users' - code which presents functionality to userspace.
> obj-$(CONFIG_MTD_BLKDEVS) += mtd_blkdevs.o
> diff --git a/drivers/mtd/sharpslpart.c b/drivers/mtd/sharpslpart.c
> new file mode 100644
> index 0000000..02b721b
> --- /dev/null
> +++ b/drivers/mtd/sharpslpart.c
> @@ -0,0 +1,391 @@
> +/*
> + * 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_PARTITION_SIZE (7 * 1024 * 1024)
> +#define PARAM_BLOCK_PARTITIONINFO1 0x00060000
> +#define PARAM_BLOCK_PARTITIONINFO2 0x00064000
> +
> +#define buf_start(x) le32_to_cpu(buf1[x].start)
> +#define buf_end(x) le32_to_cpu(buf1[x].end)
> +#define buf_magic(x) be32_to_cpu(buf1[x].magic)

Sorry, these aren't good macros; they implicitly rely on a 'buf1'
variable, without using it as an argument to the macro. That hurts
readability. If you want this macro, give it 2 args.

> +
> +#define BOOT_MAGIC 0x424f4f54 /* BOOT */
> +#define FSRO_MAGIC 0x4653524f /* FSRO */
> +#define FSRW_MAGIC 0x46535257 /* FSRW */
> +
> +/* 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 */
> +};
> +
> +struct mtd_logical *sharpsl_mtd_logical;

I asked you not to avoid making this variable static...and I suppose
technically you did this. But global is even worse! And you really don't
need to do this; just make sharpsl_nand_init_logical() return struct
mtd_logical, and then you don't need any global/static reference at all.

> +
> +/*
> + * SHARP SL FTL ancillary functions
> + *
> + */
> +
> +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;
> +}
> +
> +/*
> + * 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
> + *
> + */

Thanks for this. Much nicer.

> +
> +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);
> +
> + /* reserved */
> + if (us == BLOCK_IS_RESERVED)
> + return BLOCK_IS_RESERVED;
> + else
> + return (us & BLOCK_UNMASK) >> 1;
> +}
> +
> +int sharpsl_nand_init_logical(struct mtd_info *mtd, u32 partition_size)

static?

> +{
> + struct mtd_logical *logical;
> + u_int block_num, log_num;
> + loff_t block_adr;
> + u_char *oob;
> + int i;
> +
> + 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;

What's this for? You're re-assigning it immediately following.

> + logical->log2phy = kmalloc_array(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;
> +
> + /* 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;
> +
> + 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. Quit parser.\n");
> + kfree(logical->log2phy);
> + kfree(logical);
> + kfree(oob);
> + return -EINVAL;
> + }
> +
> + /* skip out of range and not unique values */
> + if (log_num < logical->logmax) {
> + if (logical->log2phy[log_num] == UINT_MAX)
> + logical->log2phy[log_num] = block_num;
> + }
> + }
> + 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(struct mtd_logical *sharpsl_mtd_logical)

static?

And why don't you just name the arg 'logical' and...

> +{
> + struct mtd_logical *logical = sharpsl_mtd_logical;

...drop this?

> +
> + sharpsl_mtd_logical = NULL;

If you kill the global, you don't need this.

> +
> + kfree(logical->log2phy);
> + logical->log2phy = NULL;

Not necessary.

> + kfree(logical);
> + logical = NULL;

Not necessary.

> +}
> +
> +int sharpsl_nand_read_laddr(struct mtd_info *mtd,

static?

> + loff_t from,
> + size_t len,
> + u_char *buf)
> +{
> + struct mtd_logical *logical;

Make 'logical' a parameter, so you don't need the global.

> + u_int log_num, log_new;
> + u_int block_num;
> + loff_t block_adr;
> + loff_t block_ofs;
> + size_t retlen;
> + int err;
> +
> + 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;
> +
> + err = mtd_read(mtd, block_adr + block_ofs, len, &retlen, buf);
> + /* Ignore corrected ECC errors */
> + if (mtd_is_bitflip(err))
> + err = 0;
> + if (!err && retlen != len)
> + err = -EIO;
> + if (err)
> + pr_err("sharpslpart: error, read failed at %#llx\n",
> + block_adr + block_ofs);
> +
> + return err;
> +}
> +
> +/*
> + * MTD Partition Parser
> + *
> + */
> +
> +struct sharpsl_nand_partitioninfo {
> + u32 start;
> + u32 end;

Should the above 2 be '__le32'?

> + u32 magic;

It's a little odd that the same on-flash structure would have both BE
and LE elements, but I guess judging by usage...this should be '__be32'.

> + u32 reserved;
> +};
> +
> +/*
> + * 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 ................
> + *
> + */
> +
> +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;
> + int err;
> +
> + /* init logical mgmt (FTL) */
> + if (sharpsl_nand_init_logical(master, SHARPSL_FTL_PARTITION_SIZE))
> + return -EINVAL;

Please propagate the error...

> +
> + /* read the two partition tables */
> + err = sharpsl_nand_read_laddr(master,
> + PARAM_BLOCK_PARTITIONINFO1,
> + sizeof(buf1), (u_char *)&buf1);
> + if (!err) {
> + sharpsl_nand_read_laddr(master,
> + PARAM_BLOCK_PARTITIONINFO2,
> + sizeof(buf2), (u_char *)&buf2);

You don't really need this block under the 'if'. You can just invert
this to 'if (err)', since the second block will return early.

Brian

> + } else {
> + sharpsl_nand_cleanup_logical(sharpsl_mtd_logical);
> + return err;
> + }
> +
> + /* cleanup logical mgmt (FTL) */
> + sharpsl_nand_cleanup_logical(sharpsl_mtd_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 (buf_magic(0) != BOOT_MAGIC ||
> + buf_magic(1) != FSRO_MAGIC ||
> + buf_magic(2) != FSRW_MAGIC) {
> + pr_err("sharpslpart: magic values mismatch. Quit parser.\n");
> + return -EINVAL;
> + }
> +
> + /* fixup for hardcoded value 64 MiB (for older models) */
> + buf1[2].end = cpu_to_le32(master->size);
> +
> + /* extra sanity check */
> + if (buf_end(0) <= buf_start(0) ||
> + buf_start(1) < buf_end(0) ||
> + buf_end(1) <= buf_start(1) ||
> + buf_start(2) < buf_end(1) ||
> + buf_end(2) <= buf_start(2)) {
> + pr_err("sharpslpart: partition sizes 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 = buf_start(0);
> + sharpsl_nand_parts[0].size = buf_end(0) - buf_start(0);
> +
> + sharpsl_nand_parts[1].name = "root";
> + sharpsl_nand_parts[1].offset = buf_start(1);
> + sharpsl_nand_parts[1].size = buf_end(1) - buf_start(1);
> +
> + sharpsl_nand_parts[2].name = "home";
> + sharpsl_nand_parts[2].offset = buf_start(2);
> + sharpsl_nand_parts[2].size = buf_end(2) - buf_start(2);
> +
> + *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");
> --
> 2.7.4
>

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