Date:   Sun, 16 Apr 2017 18:07:47 +0200
From:   Marek Vasut <marek.vasut@...il.com>
To:     Andrea Adami <andrea.adami@...il.com>,
        linux-mtd@...ts.infradead.org
Cc:     David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Richard Weinberger <richard@....at>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>,
        Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] mtd: sharpsl: add sharpslpart MTD partition parser

On 04/15/2017 10:11 PM, 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@...il.com>
> ---
>  drivers/mtd/Kconfig       |   8 ++
>  drivers/mtd/Makefile      |   2 +
>  drivers/mtd/sharpsl_ftl.c | 309 ++++++++++++++++++++++++++++++++++++++++++++++
>  drivers/mtd/sharpsl_ftl.h |  34 +++++
>  drivers/mtd/sharpslpart.c | 142 +++++++++++++++++++++
>  5 files changed, 495 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
> +	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

Can the FTL and partition parser be used separately ?

>  # '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..d8ebefe
> --- /dev/null
> +++ b/drivers/mtd/sharpsl_ftl.c
> @@ -0,0 +1,309 @@
> +/*
> + * MTD method for NAND accessing via logical address (SHARP FTL)
> + *
> + * Copyright (C) 2017 Andrea Adami <andrea.adami@...il.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;
> +
> +/* wrapper */
> +static int sharpsl_nand_read_oob(struct mtd_info *mtd, loff_t offs, size_t len,
> +				 size_t *retlen, uint8_t *buf)
> +{
> +	loff_t mask = mtd->writesize - 1;
> +	struct mtd_oob_ops ops;
> +	int res;
> +
> +	ops.mode = MTD_OPS_PLACE_OOB;
> +	ops.ooboffs = offs & mask;
> +	ops.ooblen = len;
> +	ops.oobbuf = buf;
> +	ops.datbuf = NULL;
> +
> +	res = mtd_read_oob(mtd, offs & ~mask, &ops);
> +	*retlen = ops.oobretlen;

You sure you want to do this assignment in all cases (also in fail case) ?

> +	return res;
> +}
> +
> +/* utility */
> +static u_int sharpsl_nand_get_logical_no(unsigned char *oob)
> +{
> +	unsigned short us, bit;
> +	int par;
> +	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]) {

Consistent indent would be nice.

> +		good0 = NAND_NOOB_LOGADDR_20;
> +		good1 = NAND_NOOB_LOGADDR_21;
> +	} else {
> +		return (u_int)-1;

What is this ?

> +	}
> +
> +	us = (((unsigned short)(oob[good0]) & 0x00ff) << 0) |
> +		(((unsigned short)(oob[good1]) & 0x00ff) << 8);

oob is unsigned char array, the cast and masking should not be needed.
btw make us into u16 type.

> +	par = 0;
> +	for (bit = 0x0001; bit != 0; bit <<= 1) {

You can use the BIT() macro here.

> +		if (us & bit)
> +			par++;
> +	}
> +	if (par & 1)
> +		return (u_int)-2;

Again, what's this return (u_int) stuff ?

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

One parenthesis set too many here.

> +}
> +
> +int sharpsl_nand_init_logical(struct mtd_info *mtd, u_int32_t partition_size)
> +{
> +	struct mtd_logical *logical = NULL;
> +	u_int block_no;
> +	loff_t block_adr;
> +	u_int log_no;
> +	unsigned char *oob = NULL;
> +	int readretry;
> +	int ret;
> +	int i;
> +	size_t retlen;
> +
> +	/* check argument */
> +	if ((partition_size % mtd->erasesize) != 0) {

Can this even happen ?

> +		pr_err("Illegal partition size. (0x%x)\n", partition_size);
> +		return -EINVAL;
> +	}
> +
> +	/* Allocate memory for Logical Address Management */
> +	logical = kzalloc(sizeof(*logical), GFP_KERNEL);
> +	if (!logical)
> +		return -ENOMEM;
> +
> +	/* Allocate a few more bytes of memory for oob */
> +	oob = kzalloc(mtd->oobsize, GFP_KERNEL);

Can we use devm_ functions all over the place ?

Can we avoid the double-allocation, ie. by embedding the maximum oob
sized buffer into struct mtd_logical (which might need renaming btw)
or allocating it on stack (it's likely a few bytes)?

> +	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);
> +
> +	pr_debug("FTL blocks: %d physical (%d logical + %d reserved)\n",
> +		 logical->phymax, logical->logmax,
> +		 logical->phymax - logical->logmax);
> +
> +	logical->log2phy = NULL;
> +
> +	/* Allocate memory for logical->log2phy */
> +	logical->log2phy = kcalloc(logical->logmax, sizeof(u_int), GFP_KERNEL);

Another allocation which could be avoided IMO

> +	if (!logical->log2phy) {
> +		kfree(logical);
> +		kfree(oob);
> +		return -ENOMEM;
> +	}
> +
> +	/* initialize logical->log2phy */
> +	for (i = 0; i < logical->logmax; i++)
> +		logical->log2phy[i] = (u_int)-1;

You should stop using this (u_int) stuff unless there's a real good
reason for that (which I doubt).

> +	/* create physical-logical table */
> +	for (block_no = 0; block_no < logical->phymax; block_no++) {
> +		block_adr = block_no * mtd->erasesize;
> +
> +		readretry = 3;
> +read_retry:
> +		/* avoid bad blocks */
> +		if (mtd_block_isbad(mtd, block_adr)) {
> +			pr_debug("block_no=%d is marked as bad, skipping\n",
> +				 block_no);

Can we use dev_dbg() and co. all over the place ?

> +			continue;
> +		}
> +
> +		/* wrapper for mtd_read_oob() */
> +		ret = sharpsl_nand_read_oob(mtd, block_adr, mtd->oobsize,
> +					    &retlen, oob);
> +
> +		if (ret != 0) {
> +			pr_warn("Failed in read_oob, skip this block.\n");
> +			continue;
> +		}
> +
> +		if (mtd->oobsize != retlen) {
> +			pr_warn("read_oob cannot read full-size.\n");
> +			continue;
> +		}
> +
> +		/* logical address */
> +		log_no = sharpsl_nand_get_logical_no(oob);
> +
> +		if ((int)log_no < 0) {

Is the typecast needed ? Probably not ...

> +			pr_warn("Bad logical no found.\n");

Bad English is found though :-) Please fix the comment.

> +			readretry--;
> +			if (readretry > 0)
> +				goto read_retry;
> +			continue;
> +		}
> +
> +		/* reserved (FTL) */
> +		if (log_no == 0xffff) {
> +			pr_debug("block_no=%d is reserved, skipping\n",
> +				 block_no);
> +			continue;
> +		}
> +
> +		/* logical address available ? */
> +		if (log_no >= logical->logmax) {
> +			pr_warn("The logical no is too big. (%d)\n", log_no);
> +			pr_warn("***partition(%d) erasesize(%d) logmax(%d)\n",
> +				partition_size, mtd->erasesize,
> +				logical->logmax);
> +		continue;

Indent.

> +		}
> +
> +		/* duplicated or not ? */
> +		if (logical->log2phy[log_no] == (u_int)(-1)) {
> +			logical->log2phy[log_no] = block_no;
> +		} else {
> +			pr_warn("The logical no is duplicated. (%d)\n", log_no);
> +			continue;

Continue not needed.

> +		}
> +
> +		/* pr_debug("FTL map: block_no=%d block_adr=0x%x log_no=%d\n",
> +		 *		block_no, (u_int32_t)block_adr, log_no);
> +		 */

Please make up your mind with this comment.

> +	}
> +	kfree(oob);
> +	sharpsl_mtd_logical = logical;
> +
> +	return 0;
> +}
> +
> +void sharpsl_nand_cleanup_logical(void)
> +{
> +	struct mtd_logical *logical = sharpsl_mtd_logical;
> +
> +	sharpsl_mtd_logical = NULL;
> +
> +	kfree(logical->log2phy);
> +	logical->log2phy = NULL;
> +	kfree(logical);
> +	logical = NULL;
> +}
> +
> +/* MTD METHOD */
> +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_no;
> +	u_int block_no;
> +	loff_t block_adr;
> +	loff_t block_ofs;
> +	size_t retlen;
> +	int ret;
> +
> +	/* support only for one block */
> +	if (len <= 0) {
> +		pr_err("Illegal argumnent. len=0x%x\n",
> +		       len);

Indent :)

> +		return -EINVAL;
> +	}
> +
> +	if ((((u_int32_t)from) / mtd->erasesize) != ((((u_int32_t)from) +
> +		len - 1) / mtd->erasesize)) {
> +		pr_err("Illegal argument. from=0x%x len=0x%x\n",
> +		       (u_int32_t)from, len);

Typecast , indent (fix globally), the condition looks like crap ...

Use u8/u16/u32 types btw

> +		return -EINVAL;
> +	}
> +
> +	logical = sharpsl_mtd_logical;
> +	log_no = (((u_int32_t)from) / mtd->erasesize);
> +
> +	if (log_no >= logical->logmax) {
> +		pr_err("Illegal argument. from=0x%x\n",
> +		       (u_int32_t)from);
> +		return -EINVAL;
> +	}
> +
> +	/* is log_no used ? */
> +	if (logical->log2phy[log_no] == (u_int)-1) {
> +		pr_err("There is not the LOGICAL block. from=0x%x\n",
> +		       (u_int32_t)from);
> +		return -EINVAL;
> +	}
> +
> +	/* physical address */
> +	block_no = logical->log2phy[log_no];
> +	block_adr = block_no * mtd->erasesize;
> +	block_ofs = (((u_int32_t)from) % mtd->erasesize);
> +
> +	/* read */
> +	ret = mtd_read(mtd, block_adr + block_ofs, len, &retlen, buf);
> +	if (ret != 0) {
> +		pr_err("mtd_read failed in sharpsl_nand_read_laddr()\n");
> +		return ret;
> +	}
> +
> +	if (len != retlen) {
> +		pr_err("mtd_read cannot read full-size.\n");
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> diff --git a/drivers/mtd/sharpsl_ftl.h b/drivers/mtd/sharpsl_ftl.h
> new file mode 100644
> index 0000000..f639646
> --- /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@...il.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, u_int32_t 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..dcd3cbe
> --- /dev/null
> +++ b/drivers/mtd/sharpslpart.c
> @@ -0,0 +1,142 @@
> +/*
> + * MTD partition parser for NAND flash on Sharp SL Series
> + *
> + * Copyright (C) 2017 Andrea Adami <andrea.adami@...il.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 boot_start;
> +	u32 boot_end;
> +	u32 boot_magic;
> +	u32 boot_reserved;

Could be reduced to

struct sharpsl_nand_partition_info {
	u32 start;
	u32 end;
	u32 magic;
	u32 reserved;
};

And then have struct sharpsl_nand_partition_info *foo; and index it with
{ 0, 1, 2 } .

> +	u32 fsro_start;
> +	u32 fsro_end;
> +	u32 fsro_magic;
> +	u32 fsro_reserved;
> +	u32 fsrw_start;
> +	u32 fsrw_end; /* ignore, was for the older models with 64M flash */
> +	u32 fsrw_magic;
> +	u32 fsrw_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;
> +	struct sharpsl_nand_partitioninfo buf2;
> +	struct mtd_partition *sharpsl_nand_parts;
> +
> +	/* init logical mgmt (FTL) */
> +	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, 48,
> +				    (u_char *)&buf1) ||
> +	    sharpsl_nand_read_laddr(master,
> +				    PARAM_BLOCK_PARTITIONINFO2, 48,
> +				    (u_char *)&buf2))
> +		return -EINVAL;
> +
> +	/* cleanup logical mgmt (FTL) */
> +	sharpsl_nand_cleanup_logical();
> +
> +	/* compare the two buffers */
> +	if (!memcmp(&buf1, &buf2, 48)) {
> +		pr_debug("sharpslpart: PARTITIONINFO 1/2 are in sync.\n");
> +	} else {
> +		pr_err("sharpslpart: PARTITIONINFO 1/2 differ. Quit parser.\n");
> +		return -EINVAL;
> +	}
> +
> +	/* check for magics (just in the first) */
> +	if (buf1.boot_magic == BOOT_MAGIC &&
> +	    buf1.fsro_magic == FSRO_MAGIC &&
> +	    buf1.fsrw_magic == FSRW_MAGIC) {
> +		pr_debug("sharpslpart: magic values found.\n");

Can we use dev_dbg() ?

> +	} else {
> +		pr_err("sharpslpart: magic values mismatch. Quit parser.\n");
> +		return -EINVAL;
> +	}

Can we use devm_kzalloc() ?

> +	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.boot_start;
> +	sharpsl_nand_parts[0].size = buf1.boot_end - buf1.boot_start;
> +	sharpsl_nand_parts[0].mask_flags = 0;
> +
> +	sharpsl_nand_parts[1].name = "root";
> +	sharpsl_nand_parts[1].offset = buf1.fsro_start;
> +	sharpsl_nand_parts[1].size = buf1.fsro_end - buf1.fsro_start;
> +	sharpsl_nand_parts[1].mask_flags = 0;
> +
> +	sharpsl_nand_parts[2].name = "home";
> +	sharpsl_nand_parts[2].offset = buf1.fsrw_start;
> +	sharpsl_nand_parts[2].size = master->size - buf1.fsrw_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@...il.com>");
> +MODULE_DESCRIPTION("MTD partitioning for NAND flash on Sharp SL Series");
> 


-- 
Best regards,
Marek Vasut

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