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095bb6e44e
User-space applications making use of MTD devices via /dev/mtd*
character devices currently have limited capabilities for reading data:
- only deprecated methods of accessing OOB layout information exist,
- there is no way to explicitly specify MTD operation mode to use; it
is auto-selected based on the MTD file mode (MTD_FILE_MODE_*) set
for the character device; in particular, this prevents using
MTD_OPS_AUTO_OOB for reads,
- all existing user-space interfaces which cause mtd_read() or
mtd_read_oob() to be called (via mtdchar_read() and
mtdchar_read_oob(), respectively) return success even when those
functions return -EUCLEAN or -EBADMSG; this renders user-space
applications using these interfaces unaware of any corrected
bitflips or uncorrectable ECC errors detected during reads.
Note that the existing MEMWRITE ioctl allows the MTD operation mode to
be explicitly set, allowing user-space applications to write page data
and OOB data without requiring them to know anything about the OOB
layout of the MTD device they are writing to (MTD_OPS_AUTO_OOB). Also,
the MEMWRITE ioctl does not mangle the return value of mtd_write_oob().
Add a new ioctl, MEMREAD, which addresses the above issues. It is
intended to be a read-side counterpart of the existing MEMWRITE ioctl.
Similarly to the latter, the read operation is performed in a loop which
processes at most mtd->erasesize bytes in each iteration. This is done
to prevent unbounded memory allocations caused by calling kmalloc() with
the 'size' argument taken directly from the struct mtd_read_req provided
by user space. However, the new ioctl is implemented so that the values
it returns match those that would have been returned if just a single
mtd_read_oob() call was issued to handle the entire read operation in
one go.
Note that while just returning -EUCLEAN or -EBADMSG to user space would
already be a valid and useful indication of the ECC algorithm detecting
errors during a read operation, that signal would not be granular enough
to cover all use cases. For example, knowing the maximum number of
bitflips detected in a single ECC step during a read operation performed
on a given page may be useful when dealing with an MTD partition whose
ECC layout varies across pages (e.g. a partition consisting of a
bootloader area using a "custom" ECC layout followed by data pages using
a "standard" ECC layout). To address that, include ECC statistics in
the structure returned to user space by the new MEMREAD ioctl.
Link: https://www.infradead.org/pipermail/linux-mtd/2016-April/067085.html
Suggested-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Michał Kępień <kernel@kempniu.pl>
Acked-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220629125737.14418-5-kernel@kempniu.pl
343 lines
12 KiB
C
343 lines
12 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
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/*
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* Copyright © 1999-2010 David Woodhouse <dwmw2@infradead.org> et al.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#ifndef __MTD_ABI_H__
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#define __MTD_ABI_H__
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#include <linux/types.h>
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struct erase_info_user {
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__u32 start;
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__u32 length;
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};
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struct erase_info_user64 {
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__u64 start;
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__u64 length;
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};
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struct mtd_oob_buf {
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__u32 start;
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__u32 length;
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unsigned char __user *ptr;
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};
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struct mtd_oob_buf64 {
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__u64 start;
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__u32 pad;
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__u32 length;
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__u64 usr_ptr;
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};
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/**
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* MTD operation modes
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*
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* @MTD_OPS_PLACE_OOB: OOB data are placed at the given offset (default)
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* @MTD_OPS_AUTO_OOB: OOB data are automatically placed at the free areas
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* which are defined by the internal ecclayout
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* @MTD_OPS_RAW: data are transferred as-is, with no error correction;
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* this mode implies %MTD_OPS_PLACE_OOB
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*
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* These modes can be passed to ioctl(MEMWRITE) and ioctl(MEMREAD); they are
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* also used internally. See notes on "MTD file modes" for discussion on
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* %MTD_OPS_RAW vs. %MTD_FILE_MODE_RAW.
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*/
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enum {
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MTD_OPS_PLACE_OOB = 0,
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MTD_OPS_AUTO_OOB = 1,
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MTD_OPS_RAW = 2,
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};
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/**
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* struct mtd_write_req - data structure for requesting a write operation
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*
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* @start: start address
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* @len: length of data buffer (only lower 32 bits are used)
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* @ooblen: length of OOB buffer (only lower 32 bits are used)
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* @usr_data: user-provided data buffer
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* @usr_oob: user-provided OOB buffer
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* @mode: MTD mode (see "MTD operation modes")
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* @padding: reserved, must be set to 0
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*
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* This structure supports ioctl(MEMWRITE) operations, allowing data and/or OOB
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* writes in various modes. To write to OOB-only, set @usr_data == NULL, and to
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* write data-only, set @usr_oob == NULL. However, setting both @usr_data and
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* @usr_oob to NULL is not allowed.
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*/
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struct mtd_write_req {
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__u64 start;
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__u64 len;
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__u64 ooblen;
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__u64 usr_data;
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__u64 usr_oob;
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__u8 mode;
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__u8 padding[7];
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};
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/**
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* struct mtd_read_req_ecc_stats - ECC statistics for a read operation
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*
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* @uncorrectable_errors: the number of uncorrectable errors that happened
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* during the read operation
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* @corrected_bitflips: the number of bitflips corrected during the read
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* operation
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* @max_bitflips: the maximum number of bitflips detected in any single ECC
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* step for the data read during the operation; this information
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* can be used to decide whether the data stored in a specific
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* region of the MTD device should be moved somewhere else to
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* avoid data loss.
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*/
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struct mtd_read_req_ecc_stats {
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__u32 uncorrectable_errors;
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__u32 corrected_bitflips;
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__u32 max_bitflips;
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};
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/**
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* struct mtd_read_req - data structure for requesting a read operation
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*
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* @start: start address
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* @len: length of data buffer (only lower 32 bits are used)
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* @ooblen: length of OOB buffer (only lower 32 bits are used)
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* @usr_data: user-provided data buffer
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* @usr_oob: user-provided OOB buffer
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* @mode: MTD mode (see "MTD operation modes")
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* @padding: reserved, must be set to 0
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* @ecc_stats: ECC statistics for the read operation
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*
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* This structure supports ioctl(MEMREAD) operations, allowing data and/or OOB
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* reads in various modes. To read from OOB-only, set @usr_data == NULL, and to
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* read data-only, set @usr_oob == NULL. However, setting both @usr_data and
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* @usr_oob to NULL is not allowed.
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*/
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struct mtd_read_req {
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__u64 start;
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__u64 len;
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__u64 ooblen;
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__u64 usr_data;
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__u64 usr_oob;
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__u8 mode;
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__u8 padding[7];
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struct mtd_read_req_ecc_stats ecc_stats;
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};
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#define MTD_ABSENT 0
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#define MTD_RAM 1
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#define MTD_ROM 2
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#define MTD_NORFLASH 3
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#define MTD_NANDFLASH 4 /* SLC NAND */
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#define MTD_DATAFLASH 6
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#define MTD_UBIVOLUME 7
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#define MTD_MLCNANDFLASH 8 /* MLC NAND (including TLC) */
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#define MTD_WRITEABLE 0x400 /* Device is writeable */
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#define MTD_BIT_WRITEABLE 0x800 /* Single bits can be flipped */
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#define MTD_NO_ERASE 0x1000 /* No erase necessary */
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#define MTD_POWERUP_LOCK 0x2000 /* Always locked after reset */
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#define MTD_SLC_ON_MLC_EMULATION 0x4000 /* Emulate SLC behavior on MLC NANDs */
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/* Some common devices / combinations of capabilities */
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#define MTD_CAP_ROM 0
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#define MTD_CAP_RAM (MTD_WRITEABLE | MTD_BIT_WRITEABLE | MTD_NO_ERASE)
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#define MTD_CAP_NORFLASH (MTD_WRITEABLE | MTD_BIT_WRITEABLE)
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#define MTD_CAP_NANDFLASH (MTD_WRITEABLE)
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#define MTD_CAP_NVRAM (MTD_WRITEABLE | MTD_BIT_WRITEABLE | MTD_NO_ERASE)
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/* Obsolete ECC byte placement modes (used with obsolete MEMGETOOBSEL) */
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#define MTD_NANDECC_OFF 0 /* Switch off ECC (Not recommended) */
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#define MTD_NANDECC_PLACE 1 /* Use the given placement in the structure (YAFFS1 legacy mode) */
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#define MTD_NANDECC_AUTOPLACE 2 /* Use the default placement scheme */
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#define MTD_NANDECC_PLACEONLY 3 /* Use the given placement in the structure (Do not store ecc result on read) */
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#define MTD_NANDECC_AUTOPL_USR 4 /* Use the given autoplacement scheme rather than using the default */
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/* OTP mode selection */
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#define MTD_OTP_OFF 0
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#define MTD_OTP_FACTORY 1
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#define MTD_OTP_USER 2
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struct mtd_info_user {
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__u8 type;
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__u32 flags;
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__u32 size; /* Total size of the MTD */
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__u32 erasesize;
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__u32 writesize;
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__u32 oobsize; /* Amount of OOB data per block (e.g. 16) */
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__u64 padding; /* Old obsolete field; do not use */
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};
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struct region_info_user {
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__u32 offset; /* At which this region starts,
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* from the beginning of the MTD */
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__u32 erasesize; /* For this region */
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__u32 numblocks; /* Number of blocks in this region */
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__u32 regionindex;
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};
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struct otp_info {
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__u32 start;
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__u32 length;
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__u32 locked;
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};
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/*
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* Note, the following ioctl existed in the past and was removed:
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* #define MEMSETOOBSEL _IOW('M', 9, struct nand_oobinfo)
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* Try to avoid adding a new ioctl with the same ioctl number.
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*/
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/* Get basic MTD characteristics info (better to use sysfs) */
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#define MEMGETINFO _IOR('M', 1, struct mtd_info_user)
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/* Erase segment of MTD */
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#define MEMERASE _IOW('M', 2, struct erase_info_user)
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/* Write out-of-band data from MTD */
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#define MEMWRITEOOB _IOWR('M', 3, struct mtd_oob_buf)
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/* Read out-of-band data from MTD */
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#define MEMREADOOB _IOWR('M', 4, struct mtd_oob_buf)
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/* Lock a chip (for MTD that supports it) */
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#define MEMLOCK _IOW('M', 5, struct erase_info_user)
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/* Unlock a chip (for MTD that supports it) */
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#define MEMUNLOCK _IOW('M', 6, struct erase_info_user)
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/* Get the number of different erase regions */
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#define MEMGETREGIONCOUNT _IOR('M', 7, int)
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/* Get information about the erase region for a specific index */
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#define MEMGETREGIONINFO _IOWR('M', 8, struct region_info_user)
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/* Get info about OOB modes (e.g., RAW, PLACE, AUTO) - legacy interface */
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#define MEMGETOOBSEL _IOR('M', 10, struct nand_oobinfo)
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/* Check if an eraseblock is bad */
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#define MEMGETBADBLOCK _IOW('M', 11, __kernel_loff_t)
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/* Mark an eraseblock as bad */
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#define MEMSETBADBLOCK _IOW('M', 12, __kernel_loff_t)
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/* Set OTP (One-Time Programmable) mode (factory vs. user) */
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#define OTPSELECT _IOR('M', 13, int)
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/* Get number of OTP (One-Time Programmable) regions */
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#define OTPGETREGIONCOUNT _IOW('M', 14, int)
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/* Get all OTP (One-Time Programmable) info about MTD */
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#define OTPGETREGIONINFO _IOW('M', 15, struct otp_info)
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/* Lock a given range of user data (must be in mode %MTD_FILE_MODE_OTP_USER) */
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#define OTPLOCK _IOR('M', 16, struct otp_info)
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/* Get ECC layout (deprecated) */
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#define ECCGETLAYOUT _IOR('M', 17, struct nand_ecclayout_user)
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/* Get statistics about corrected/uncorrected errors */
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#define ECCGETSTATS _IOR('M', 18, struct mtd_ecc_stats)
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/* Set MTD mode on a per-file-descriptor basis (see "MTD file modes") */
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#define MTDFILEMODE _IO('M', 19)
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/* Erase segment of MTD (supports 64-bit address) */
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#define MEMERASE64 _IOW('M', 20, struct erase_info_user64)
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/* Write data to OOB (64-bit version) */
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#define MEMWRITEOOB64 _IOWR('M', 21, struct mtd_oob_buf64)
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/* Read data from OOB (64-bit version) */
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#define MEMREADOOB64 _IOWR('M', 22, struct mtd_oob_buf64)
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/* Check if chip is locked (for MTD that supports it) */
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#define MEMISLOCKED _IOR('M', 23, struct erase_info_user)
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/*
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* Most generic write interface; can write in-band and/or out-of-band in various
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* modes (see "struct mtd_write_req"). This ioctl is not supported for flashes
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* without OOB, e.g., NOR flash.
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*/
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#define MEMWRITE _IOWR('M', 24, struct mtd_write_req)
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/* Erase a given range of user data (must be in mode %MTD_FILE_MODE_OTP_USER) */
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#define OTPERASE _IOW('M', 25, struct otp_info)
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/*
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* Most generic read interface; can read in-band and/or out-of-band in various
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* modes (see "struct mtd_read_req"). This ioctl is not supported for flashes
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* without OOB, e.g., NOR flash.
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*/
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#define MEMREAD _IOWR('M', 26, struct mtd_read_req)
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/*
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* Obsolete legacy interface. Keep it in order not to break userspace
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* interfaces
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*/
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struct nand_oobinfo {
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__u32 useecc;
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__u32 eccbytes;
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__u32 oobfree[8][2];
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__u32 eccpos[32];
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};
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struct nand_oobfree {
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__u32 offset;
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__u32 length;
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};
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#define MTD_MAX_OOBFREE_ENTRIES 8
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#define MTD_MAX_ECCPOS_ENTRIES 64
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/*
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* OBSOLETE: ECC layout control structure. Exported to user-space via ioctl
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* ECCGETLAYOUT for backwards compatbility and should not be mistaken as a
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* complete set of ECC information. The ioctl truncates the larger internal
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* structure to retain binary compatibility with the static declaration of the
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* ioctl. Note that the "MTD_MAX_..._ENTRIES" macros represent the max size of
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* the user struct, not the MAX size of the internal OOB layout representation.
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*/
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struct nand_ecclayout_user {
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__u32 eccbytes;
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__u32 eccpos[MTD_MAX_ECCPOS_ENTRIES];
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__u32 oobavail;
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struct nand_oobfree oobfree[MTD_MAX_OOBFREE_ENTRIES];
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};
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/**
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* struct mtd_ecc_stats - error correction stats
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*
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* @corrected: number of corrected bits
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* @failed: number of uncorrectable errors
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* @badblocks: number of bad blocks in this partition
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* @bbtblocks: number of blocks reserved for bad block tables
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*/
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struct mtd_ecc_stats {
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__u32 corrected;
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__u32 failed;
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__u32 badblocks;
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__u32 bbtblocks;
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};
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/*
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* MTD file modes - for read/write access to MTD
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*
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* @MTD_FILE_MODE_NORMAL: OTP disabled, ECC enabled
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* @MTD_FILE_MODE_OTP_FACTORY: OTP enabled in factory mode
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* @MTD_FILE_MODE_OTP_USER: OTP enabled in user mode
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* @MTD_FILE_MODE_RAW: OTP disabled, ECC disabled
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*
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* These modes can be set via ioctl(MTDFILEMODE). The mode will be retained
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* separately for each open file descriptor.
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*
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* Note: %MTD_FILE_MODE_RAW provides the same functionality as %MTD_OPS_RAW -
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* raw access to the flash, without error correction or autoplacement schemes.
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* Wherever possible, the MTD_OPS_* mode will override the MTD_FILE_MODE_* mode
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* (e.g., when using ioctl(MEMWRITE) or ioctl(MEMREAD)), but in some cases, the
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* MTD_FILE_MODE is used out of necessity (e.g., `write()',
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* ioctl(MEMWRITEOOB64)).
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*/
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enum mtd_file_modes {
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MTD_FILE_MODE_NORMAL = MTD_OTP_OFF,
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MTD_FILE_MODE_OTP_FACTORY = MTD_OTP_FACTORY,
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MTD_FILE_MODE_OTP_USER = MTD_OTP_USER,
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MTD_FILE_MODE_RAW,
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};
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static inline int mtd_type_is_nand_user(const struct mtd_info_user *mtd)
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{
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return mtd->type == MTD_NANDFLASH || mtd->type == MTD_MLCNANDFLASH;
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}
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#endif /* __MTD_ABI_H__ */
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