Re: [PATCH v2 37/53] docs-rst: convert mtdnand book to ReST

Boris Brezillon
2017-05-16T13:11:58Z

On Tue, 16 May 2017 09:16:29 -0300
Mauro Carvalho Chehab <mchehab@s-opensource.com> wrote:

> Use pandoc to convert documentation to ReST by calling
> Documentation/sphinx/tmplcvt script.
>
> The tables were manually adjusted to fit into 80 columns.
>
> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>

> ---
> Documentation/DocBook/Makefile | 1 -
> Documentation/DocBook/mtdnand.tmpl | 1291 ----------------------------------
> Documentation/driver-api/index.rst | 1 +
> Documentation/driver-api/mtdnand.rst | 1020 +++++++++++++++++++++++++++
> 4 files changed, 1021 insertions(+), 1292 deletions(-)
> delete mode 100644 Documentation/DocBook/mtdnand.tmpl
> create mode 100644 Documentation/driver-api/mtdnand.rst
>
> diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
> index 0a82f6253682..226e5e9fc801 100644
> --- a/Documentation/DocBook/Makefile
> +++ b/Documentation/DocBook/Makefile
> @@ -8,7 +8,6 @@
>
> DOCBOOKS := \
> lsm.xml \
> - mtdnand.xml \
> sh.xml
>
> ifeq ($(DOCBOOKS),)
> diff --git a/Documentation/DocBook/mtdnand.tmpl b/Documentation/DocBook/mtdnand.tmpl
> deleted file mode 100644
> index b442921bca54..000000000000
> --- a/Documentation/DocBook/mtdnand.tmpl
> +++ /dev/null
> @@ -1,1291 +0,0 @@
> -<?xml version="1.0" encoding="UTF-8"?>
> -<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
> - "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
> -
> -<book id="MTD-NAND-Guide">
> - <bookinfo>
> - MTD NAND Driver Programming Interface
> -
> - <authorgroup>
> - <author>
> - <firstname>Thomas</firstname>
> - <surname>Gleixner</surname>
> - <affiliation>
> -
> - <email>tglx@linutronix.de</email>
> -
> - </affiliation>
> - </author>
> - </authorgroup>
> -
> - <copyright>
> - <year>2004</year>
> - <holder>Thomas Gleixner</holder>
> - </copyright>
> -
> - <legalnotice>
> -
> - This documentation is free software; you can redistribute
> - it and/or modify it under the terms of the GNU General Public
> - License version 2 as published by the Free Software Foundation.
> -
> -
> -
> - 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.
> -
> -
> -
> - You should have received a copy of the GNU General Public
> - License along with this program; if not, write to the Free
> - Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> - MA 02111-1307 USA
> -
> -
> -
> - For more details see the file COPYING in the source
> - distribution of Linux.
> -
> - </legalnotice>
> - </bookinfo>
> -
> -<toc></toc>
> -
> - <chapter id="intro">
> - Introduction
> -
> - The generic NAND driver supports almost all NAND and AG-AND based
> - chips and connects them to the Memory Technology Devices (MTD)
> - subsystem of the Linux Kernel.
> -
> -
> - This documentation is provided for developers who want to implement
> - board drivers or filesystem drivers suitable for NAND devices.
> -
> - </chapter>
> -
> - <chapter id="bugs">
> - Known Bugs And Assumptions
> -
> - None.
> -
> - </chapter>
> -
> - <chapter id="dochints">
> - Documentation hints
> -
> - The function and structure docs are autogenerated. Each function and
> - struct member has a short description which is marked with an [XXX] identifier.
> - The following chapters explain the meaning of those identifiers.
> -
> - <sect1 id="Function_identifiers_XXX">
> - Function identifiers [XXX]
> -
> - The functions are marked with [XXX] identifiers in the short
> - comment. The identifiers explain the usage and scope of the
> - functions. Following identifiers are used:
> -
> -
> -
> - [MTD Interface]
> - These functions provide the interface to the MTD kernel API.
> - They are not replaceable and provide functionality
> - which is complete hardware independent.
> -
> -
> - [NAND Interface]
> - These functions are exported and provide the interface to the NAND kernel API.
> -
> -
> - [GENERIC]
> - Generic functions are not replaceable and provide functionality
> - which is complete hardware independent.
> -
> -
> - [DEFAULT]
> - Default functions provide hardware related functionality which is suitable
> - for most of the implementations. These functions can be replaced by the
> - board driver if necessary. Those functions are called via pointers in the
> - NAND chip description structure. The board driver can set the functions which
> - should be replaced by board dependent functions before calling nand_scan().
> - If the function pointer is NULL on entry to nand_scan() then the pointer
> - is set to the default function which is suitable for the detected chip type.
> -
> -
> - </sect1>
> - <sect1 id="Struct_member_identifiers_XXX">
> - Struct member identifiers [XXX]
> -
> - The struct members are marked with [XXX] identifiers in the
> - comment. The identifiers explain the usage and scope of the
> - members. Following identifiers are used:
> -
> -
> -
> - [INTERN]
> - These members are for NAND driver internal use only and must not be
> - modified. Most of these values are calculated from the chip geometry
> - information which is evaluated during nand_scan().
> -
> -
> - [REPLACEABLE]
> - Replaceable members hold hardware related functions which can be
> - provided by the board driver. The board driver can set the functions which
> - should be replaced by board dependent functions before calling nand_scan().
> - If the function pointer is NULL on entry to nand_scan() then the pointer
> - is set to the default function which is suitable for the detected chip type.
> -
> -
> - [BOARDSPECIFIC]
> - Board specific members hold hardware related information which must
> - be provided by the board driver. The board driver must set the function
> - pointers and datafields before calling nand_scan().
> -
> -
> - [OPTIONAL]
> - Optional members can hold information relevant for the board driver. The
> - generic NAND driver code does not use this information.
> -
> -
> - </sect1>
> - </chapter>
> -
> - <chapter id="basicboarddriver">
> - Basic board driver
> -
> - For most boards it will be sufficient to provide just the
> - basic functions and fill out some really board dependent
> - members in the nand chip description structure.
> -
> - <sect1 id="Basic_defines">
> - Basic defines
> -
> - At least you have to provide a nand_chip structure
> - and a storage for the ioremap'ed chip address.
> - You can allocate the nand_chip structure using
> - kmalloc or you can allocate it statically.
> - The NAND chip structure embeds an mtd structure
> - which will be registered to the MTD subsystem.
> - You can extract a pointer to the mtd structure
> - from a nand_chip pointer using the nand_to_mtd()
> - helper.
> -
> -
> - Kmalloc based example
> -
> - <programlisting>
> -static struct mtd_info *board_mtd;
> -static void __iomem *baseaddr;
> - </programlisting>
> -
> - Static example
> -
> - <programlisting>
> -static struct nand_chip board_chip;
> -static void __iomem *baseaddr;
> - </programlisting>
> - </sect1>
> - <sect1 id="Partition_defines">
> - Partition defines
> -
> - If you want to divide your device into partitions, then
> - define a partitioning scheme suitable to your board.
> -
> - <programlisting>
> -#define NUM_PARTITIONS 2
> -static struct mtd_partition partition_info[] = {
> - { .name = "Flash partition 1",
> - .offset = 0,
> - .size = 8 * 1024 * 1024 },
> - { .name = "Flash partition 2",
> - .offset = MTDPART_OFS_NEXT,
> - .size = MTDPART_SIZ_FULL },
> -};
> - </programlisting>
> - </sect1>
> - <sect1 id="Hardware_control_functions">
> - Hardware control function
> -
> - The hardware control function provides access to the
> - control pins of the NAND chip(s).
> - The access can be done by GPIO pins or by address lines.
> - If you use address lines, make sure that the timing
> - requirements are met.
> -
> -
> - GPIO based example
> -
> - <programlisting>
> -static void board_hwcontrol(struct mtd_info *mtd, int cmd)
> -{
> - switch(cmd){
> - case NAND_CTL_SETCLE: /* Set CLE pin high */ break;
> - case NAND_CTL_CLRCLE: /* Set CLE pin low */ break;
> - case NAND_CTL_SETALE: /* Set ALE pin high */ break;
> - case NAND_CTL_CLRALE: /* Set ALE pin low */ break;
> - case NAND_CTL_SETNCE: /* Set nCE pin low */ break;
> - case NAND_CTL_CLRNCE: /* Set nCE pin high */ break;
> - }
> -}
> - </programlisting>
> -
> - Address lines based example. It's assumed that the
> - nCE pin is driven by a chip select decoder.
> -
> - <programlisting>
> -static void board_hwcontrol(struct mtd_info *mtd, int cmd)
> -{
> - struct nand_chip *this = mtd_to_nand(mtd);
> - switch(cmd){
> - case NAND_CTL_SETCLE: this->IO_ADDR_W |= CLE_ADRR_BIT; break;
> - case NAND_CTL_CLRCLE: this->IO_ADDR_W &amp;= ~CLE_ADRR_BIT; break;
> - case NAND_CTL_SETALE: this->IO_ADDR_W |= ALE_ADRR_BIT; break;
> - case NAND_CTL_CLRALE: this->IO_ADDR_W &amp;= ~ALE_ADRR_BIT; break;
> - }
> -}
> - </programlisting>
> - </sect1>
> - <sect1 id="Device_ready_function">
> - Device ready function
> -
> - If the hardware interface has the ready busy pin of the NAND chip connected to a
> - GPIO or other accessible I/O pin, this function is used to read back the state of the
> - pin. The function has no arguments and should return 0, if the device is busy (R/B pin
> - is low) and 1, if the device is ready (R/B pin is high).
> - If the hardware interface does not give access to the ready busy pin, then
> - the function must not be defined and the function pointer this->dev_ready is set to NULL.
> -
> - </sect1>
> - <sect1 id="Init_function">
> - Init function
> -
> - The init function allocates memory and sets up all the board
> - specific parameters and function pointers. When everything
> - is set up nand_scan() is called. This function tries to
> - detect and identify then chip. If a chip is found all the
> - internal data fields are initialized accordingly.
> - The structure(s) have to be zeroed out first and then filled with the necessary
> - information about the device.
> -
> - <programlisting>
> -static int __init board_init (void)
> -{
> - struct nand_chip *this;
> - int err = 0;
> -
> - /* Allocate memory for MTD device structure and private data */
> - this = kzalloc(sizeof(struct nand_chip), GFP_KERNEL);
> - if (!this) {
> - printk ("Unable to allocate NAND MTD device structure.\n");
> - err = -ENOMEM;
> - goto out;
> - }
> -
> - board_mtd = nand_to_mtd(this);
> -
> - /* map physical address */
> - baseaddr = ioremap(CHIP_PHYSICAL_ADDRESS, 1024);
> - if (!baseaddr) {
> - printk("Ioremap to access NAND chip failed\n");
> - err = -EIO;
> - goto out_mtd;
> - }
> -
> - /* Set address of NAND IO lines */
> - this->IO_ADDR_R = baseaddr;
> - this->IO_ADDR_W = baseaddr;
> - /* Reference hardware control function */
> - this->hwcontrol = board_hwcontrol;
> - /* Set command delay time, see datasheet for correct value */
> - this->chip_delay = CHIP_DEPENDEND_COMMAND_DELAY;
> - /* Assign the device ready function, if available */
> - this->dev_ready = board_dev_ready;
> - this->eccmode = NAND_ECC_SOFT;
> -
> - /* Scan to find existence of the device */
> - if (nand_scan (board_mtd, 1)) {
> - err = -ENXIO;
> - goto out_ior;
> - }
> -
> - add_mtd_partitions(board_mtd, partition_info, NUM_PARTITIONS);
> - goto out;
> -
> -out_ior:
> - iounmap(baseaddr);
> -out_mtd:
> - kfree (this);
> -out:
> - return err;
> -}
> -module_init(board_init);
> - </programlisting>
> - </sect1>
> - <sect1 id="Exit_function">
> - Exit function
> -
> - The exit function is only necessary if the driver is
> - compiled as a module. It releases all resources which
> - are held by the chip driver and unregisters the partitions
> - in the MTD layer.
> -
> - <programlisting>
> -#ifdef MODULE
> -static void __exit board_cleanup (void)
> -{
> - /* Release resources, unregister device */
> - nand_release (board_mtd);
> -
> - /* unmap physical address */
> - iounmap(baseaddr);
> -
> - /* Free the MTD device structure */
> - kfree (mtd_to_nand(board_mtd));
> -}
> -module_exit(board_cleanup);
> -#endif
> - </programlisting>
> - </sect1>
> - </chapter>
> -
> - <chapter id="boarddriversadvanced">
> - Advanced board driver functions
> -
> - This chapter describes the advanced functionality of the NAND
> - driver. For a list of functions which can be overridden by the board
> - driver see the documentation of the nand_chip structure.
> -
> - <sect1 id="Multiple_chip_control">
> - Multiple chip control
> -
> - The nand driver can control chip arrays. Therefore the
> - board driver must provide an own select_chip function. This
> - function must (de)select the requested chip.
> - The function pointer in the nand_chip structure must
> - be set before calling nand_scan(). The maxchip parameter
> - of nand_scan() defines the maximum number of chips to
> - scan for. Make sure that the select_chip function can
> - handle the requested number of chips.
> -
> -
> - The nand driver concatenates the chips to one virtual
> - chip and provides this virtual chip to the MTD layer.
> -
> -
> - Note: The driver can only handle linear chip arrays
> - of equally sized chips. There is no support for
> - parallel arrays which extend the buswidth.
> -
> -
> - GPIO based example
> -
> - <programlisting>
> -static void board_select_chip (struct mtd_info *mtd, int chip)
> -{
> - /* Deselect all chips, set all nCE pins high */
> - GPIO(BOARD_NAND_NCE) |= 0xff;
> - if (chip >= 0)
> - GPIO(BOARD_NAND_NCE) &amp;= ~ (1 &lt;&lt; chip);
> -}
> - </programlisting>
> -
> - Address lines based example.
> - Its assumed that the nCE pins are connected to an
> - address decoder.
> -
> - <programlisting>
> -static void board_select_chip (struct mtd_info *mtd, int chip)
> -{
> - struct nand_chip *this = mtd_to_nand(mtd);
> -
> - /* Deselect all chips */
> - this->IO_ADDR_R &amp;= ~BOARD_NAND_ADDR_MASK;
> - this->IO_ADDR_W &amp;= ~BOARD_NAND_ADDR_MASK;
> - switch (chip) {
> - case 0:
> - this->IO_ADDR_R |= BOARD_NAND_ADDR_CHIP0;
> - this->IO_ADDR_W |= BOARD_NAND_ADDR_CHIP0;
> - break;
> - ....
> - case n:
> - this->IO_ADDR_R |= BOARD_NAND_ADDR_CHIPn;
> - this->IO_ADDR_W |= BOARD_NAND_ADDR_CHIPn;
> - break;
> - }
> -}
> - </programlisting>
> - </sect1>
> - <sect1 id="Hardware_ECC_support">
> - Hardware ECC support
> - <sect2 id="Functions_and_constants">
> - Functions and constants
> -
> - The nand driver supports three different types of
> - hardware ECC.
> -
> - NAND_ECC_HW3_256
> - Hardware ECC generator providing 3 bytes ECC per
> - 256 byte.
> -
> - NAND_ECC_HW3_512
> - Hardware ECC generator providing 3 bytes ECC per
> - 512 byte.
> -
> - NAND_ECC_HW6_512
> - Hardware ECC generator providing 6 bytes ECC per
> - 512 byte.
> -
> - NAND_ECC_HW8_512
> - Hardware ECC generator providing 6 bytes ECC per
> - 512 byte.
> -
> -
> - If your hardware generator has a different functionality
> - add it at the appropriate place in nand_base.c
> -
> -
> - The board driver must provide following functions:
> -
> - enable_hwecc
> - This function is called before reading / writing to
> - the chip. Reset or initialize the hardware generator
> - in this function. The function is called with an
> - argument which let you distinguish between read
> - and write operations.
> -
> - calculate_ecc
> - This function is called after read / write from / to
> - the chip. Transfer the ECC from the hardware to
> - the buffer. If the option NAND_HWECC_SYNDROME is set
> - then the function is only called on write. See below.
> -
> - correct_data
> - In case of an ECC error this function is called for
> - error detection and correction. Return 1 respectively 2
> - in case the error can be corrected. If the error is
> - not correctable return -1. If your hardware generator
> - matches the default algorithm of the nand_ecc software
> - generator then use the correction function provided
> - by nand_ecc instead of implementing duplicated code.
> -
> -
> -
> - </sect2>
> - <sect2 id="Hardware_ECC_with_syndrome_calculation">
> - Hardware ECC with syndrome calculation
> -
> - Many hardware ECC implementations provide Reed-Solomon
> - codes and calculate an error syndrome on read. The syndrome
> - must be converted to a standard Reed-Solomon syndrome
> - before calling the error correction code in the generic
> - Reed-Solomon library.
> -
> -
> - The ECC bytes must be placed immediately after the data
> - bytes in order to make the syndrome generator work. This
> - is contrary to the usual layout used by software ECC. The
> - separation of data and out of band area is not longer
> - possible. The nand driver code handles this layout and
> - the remaining free bytes in the oob area are managed by
> - the autoplacement code. Provide a matching oob-layout
> - in this case. See rts_from4.c and diskonchip.c for
> - implementation reference. In those cases we must also
> - use bad block tables on FLASH, because the ECC layout is
> - interfering with the bad block marker positions.
> - See bad block table support for details.
> -
> - </sect2>
> - </sect1>
> - <sect1 id="Bad_Block_table_support">
> - Bad block table support
> -
> - Most NAND chips mark the bad blocks at a defined
> - position in the spare area. Those blocks must
> - not be erased under any circumstances as the bad
> - block information would be lost.
> - It is possible to check the bad block mark each
> - time when the blocks are accessed by reading the
> - spare area of the first page in the block. This
> - is time consuming so a bad block table is used.
> -
> -
> - The nand driver supports various types of bad block
> - tables.
> -
> - Per device
> - The bad block table contains all bad block information
> - of the device which can consist of multiple chips.
> -
> - Per chip
> - A bad block table is used per chip and contains the
> - bad block information for this particular chip.
> -
> - Fixed offset
> - The bad block table is located at a fixed offset
> - in the chip (device). This applies to various
> - DiskOnChip devices.
> -
> - Automatic placed
> - The bad block table is automatically placed and
> - detected either at the end or at the beginning
> - of a chip (device)
> -
> - Mirrored tables
> - The bad block table is mirrored on the chip (device) to
> - allow updates of the bad block table without data loss.
> -
> -
> -
> -
> - nand_scan() calls the function nand_default_bbt().
> - nand_default_bbt() selects appropriate default
> - bad block table descriptors depending on the chip information
> - which was retrieved by nand_scan().
> -
> -
> - The standard policy is scanning the device for bad
> - blocks and build a ram based bad block table which
> - allows faster access than always checking the
> - bad block information on the flash chip itself.
> -
> - <sect2 id="Flash_based_tables">
> - Flash based tables
> -
> - It may be desired or necessary to keep a bad block table in FLASH.
> - For AG-AND chips this is mandatory, as they have no factory marked
> - bad blocks. They have factory marked good blocks. The marker pattern
> - is erased when the block is erased to be reused. So in case of
> - powerloss before writing the pattern back to the chip this block
> - would be lost and added to the bad blocks. Therefore we scan the
> - chip(s) when we detect them the first time for good blocks and
> - store this information in a bad block table before erasing any
> - of the blocks.
> -
> -
> - The blocks in which the tables are stored are protected against
> - accidental access by marking them bad in the memory bad block
> - table. The bad block table management functions are allowed
> - to circumvent this protection.
> -
> -
> - The simplest way to activate the FLASH based bad block table support
> - is to set the option NAND_BBT_USE_FLASH in the bbt_option field of
> - the nand chip structure before calling nand_scan(). For AG-AND
> - chips is this done by default.
> - This activates the default FLASH based bad block table functionality
> - of the NAND driver. The default bad block table options are
> -
> - Store bad block table per chip
> - Use 2 bits per block
> - Automatic placement at the end of the chip
> - Use mirrored tables with version numbers
> - Reserve 4 blocks at the end of the chip
> -
> -
> - </sect2>
> - <sect2 id="User_defined_tables">
> - User defined tables
> -
> - User defined tables are created by filling out a
> - nand_bbt_descr structure and storing the pointer in the
> - nand_chip structure member bbt_td before calling nand_scan().
> - If a mirror table is necessary a second structure must be
> - created and a pointer to this structure must be stored
> - in bbt_md inside the nand_chip structure. If the bbt_md
> - member is set to NULL then only the main table is used
> - and no scan for the mirrored table is performed.
> -
> -
> - The most important field in the nand_bbt_descr structure
> - is the options field. The options define most of the
> - table properties. Use the predefined constants from
> - nand.h to define the options.
> -
> - Number of bits per block
> - The supported number of bits is 1, 2, 4, 8.
> - Table per chip
> - Setting the constant NAND_BBT_PERCHIP selects that
> - a bad block table is managed for each chip in a chip array.
> - If this option is not set then a per device bad block table
> - is used.
> - Table location is absolute
> - Use the option constant NAND_BBT_ABSPAGE and
> - define the absolute page number where the bad block
> - table starts in the field pages. If you have selected bad block
> - tables per chip and you have a multi chip array then the start page
> - must be given for each chip in the chip array. Note: there is no scan
> - for a table ident pattern performed, so the fields
> - pattern, veroffs, offs, len can be left uninitialized
> - Table location is automatically detected
> - The table can either be located in the first or the last good
> - blocks of the chip (device). Set NAND_BBT_LASTBLOCK to place
> - the bad block table at the end of the chip (device). The
> - bad block tables are marked and identified by a pattern which
> - is stored in the spare area of the first page in the block which
> - holds the bad block table. Store a pointer to the pattern
> - in the pattern field. Further the length of the pattern has to be
> - stored in len and the offset in the spare area must be given
> - in the offs member of the nand_bbt_descr structure. For mirrored
> - bad block tables different patterns are mandatory.
> - Table creation
> - Set the option NAND_BBT_CREATE to enable the table creation
> - if no table can be found during the scan. Usually this is done only
> - once if a new chip is found.
> - Table write support
> - Set the option NAND_BBT_WRITE to enable the table write support.
> - This allows the update of the bad block table(s) in case a block has
> - to be marked bad due to wear. The MTD interface function block_markbad
> - is calling the update function of the bad block table. If the write
> - support is enabled then the table is updated on FLASH.
> -
> - Note: Write support should only be enabled for mirrored tables with
> - version control.
> -
> - Table version control
> - Set the option NAND_BBT_VERSION to enable the table version control.
> - It's highly recommended to enable this for mirrored tables with write
> - support. It makes sure that the risk of losing the bad block
> - table information is reduced to the loss of the information about the
> - one worn out block which should be marked bad. The version is stored in
> - 4 consecutive bytes in the spare area of the device. The position of
> - the version number is defined by the member veroffs in the bad block table
> - descriptor.
> - Save block contents on write
> -
> - In case that the block which holds the bad block table does contain
> - other useful information, set the option NAND_BBT_SAVECONTENT. When
> - the bad block table is written then the whole block is read the bad
> - block table is updated and the block is erased and everything is
> - written back. If this option is not set only the bad block table
> - is written and everything else in the block is ignored and erased.
> -
> - Number of reserved blocks
> -
> - For automatic placement some blocks must be reserved for
> - bad block table storage. The number of reserved blocks is defined
> - in the maxblocks member of the bad block table description structure.
> - Reserving 4 blocks for mirrored tables should be a reasonable number.
> - This also limits the number of blocks which are scanned for the bad
> - block table ident pattern.
> -
> -
> -
> - </sect2>
> - </sect1>
> - <sect1 id="Spare_area_placement">
> - Spare area (auto)placement
> -
> - The nand driver implements different possibilities for
> - placement of filesystem data in the spare area,
> -
> - Placement defined by fs driver
> - Automatic placement
> -
> - The default placement function is automatic placement. The
> - nand driver has built in default placement schemes for the
> - various chiptypes. If due to hardware ECC functionality the
> - default placement does not fit then the board driver can
> - provide a own placement scheme.
> -
> -
> - File system drivers can provide a own placement scheme which
> - is used instead of the default placement scheme.
> -
> -
> - Placement schemes are defined by a nand_oobinfo structure
> - <programlisting>
> -struct nand_oobinfo {
> - int useecc;
> - int eccbytes;
> - int eccpos[24];
> - int oobfree[8][2];
> -};
> - </programlisting>
> -
> - useecc
> - The useecc member controls the ecc and placement function. The header
> - file include/mtd/mtd-abi.h contains constants to select ecc and
> - placement. MTD_NANDECC_OFF switches off the ecc complete. This is
> - not recommended and available for testing and diagnosis only.
> - MTD_NANDECC_PLACE selects caller defined placement, MTD_NANDECC_AUTOPLACE
> - selects automatic placement.
> -
> - eccbytes
> - The eccbytes member defines the number of ecc bytes per page.
> -
> - eccpos
> - The eccpos array holds the byte offsets in the spare area where
> - the ecc codes are placed.
> -
> - oobfree
> - The oobfree array defines the areas in the spare area which can be
> - used for automatic placement. The information is given in the format
> - {offset, size}. offset defines the start of the usable area, size the
> - length in bytes. More than one area can be defined. The list is terminated
> - by an {0, 0} entry.
> -
> -
> -
> - <sect2 id="Placement_defined_by_fs_driver">
> - Placement defined by fs driver
> -
> - The calling function provides a pointer to a nand_oobinfo
> - structure which defines the ecc placement. For writes the
> - caller must provide a spare area buffer along with the
> - data buffer. The spare area buffer size is (number of pages) *
> - (size of spare area). For reads the buffer size is
> - (number of pages) * ((size of spare area) + (number of ecc
> - steps per page) * sizeof (int)). The driver stores the
> - result of the ecc check for each tuple in the spare buffer.
> - The storage sequence is
> -
> -
> - &lt;spare data page 0&gt;&lt;ecc result 0&gt;...&lt;ecc result n&gt;
> -
> -
> - ...
> -
> -
> - &lt;spare data page n&gt;&lt;ecc result 0&gt;...&lt;ecc result n&gt;
> -
> -
> - This is a legacy mode used by YAFFS1.
> -
> -
> - If the spare area buffer is NULL then only the ECC placement is
> - done according to the given scheme in the nand_oobinfo structure.
> -
> - </sect2>
> - <sect2 id="Automatic_placement">
> - Automatic placement
> -
> - Automatic placement uses the built in defaults to place the
> - ecc bytes in the spare area. If filesystem data have to be stored /
> - read into the spare area then the calling function must provide a
> - buffer. The buffer size per page is determined by the oobfree array in
> - the nand_oobinfo structure.
> -
> -
> - If the spare area buffer is NULL then only the ECC placement is
> - done according to the default builtin scheme.
> -
> - </sect2>
> - </sect1>
> - <sect1 id="Spare_area_autoplacement_default">
> - Spare area autoplacement default schemes
> - <sect2 id="pagesize_256">
> - 256 byte pagesize
> -<informaltable><tgroup cols="3">
> -<row>
> -<entry>Offset</entry>
> -<entry>Content</entry>
> -<entry>Comment</entry>
> -</row>
> -<row>
> -<entry>0x00</entry>
> -<entry>ECC byte 0</entry>
> -<entry>Error correction code byte 0</entry>
> -</row>
> -<row>
> -<entry>0x01</entry>
> -<entry>ECC byte 1</entry>
> -<entry>Error correction code byte 1</entry>
> -</row>
> -<row>
> -<entry>0x02</entry>
> -<entry>ECC byte 2</entry>
> -<entry>Error correction code byte 2</entry>
> -</row>
> -<row>
> -<entry>0x03</entry>
> -<entry>Autoplace 0</entry>
> -<entry></entry>
> -</row>
> -<row>
> -<entry>0x04</entry>
> -<entry>Autoplace 1</entry>
> -<entry></entry>
> -</row>
> -<row>
> -<entry>0x05</entry>
> -<entry>Bad block marker</entry>
> -<entry>If any bit in this byte is zero, then this block is bad.
> -This applies only to the first page in a block. In the remaining
> -pages this byte is reserved</entry>
> -</row>
> -<row>
> -<entry>0x06</entry>
> -<entry>Autoplace 2</entry>
> -<entry></entry>
> -</row>
> -<row>
> -<entry>0x07</entry>
> -<entry>Autoplace 3</entry>
> -<entry></entry>
> -</row>
> - </tgroup></informaltable>
> - </sect2>
> - <sect2 id="pagesize_512">
> - 512 byte pagesize
> -<informaltable><tgroup cols="3">
> -<row>
> -<entry>Offset</entry>
> -<entry>Content</entry>
> -<entry>Comment</entry>
> -</row>
> -<row>
> -<entry>0x00</entry>
> -<entry>ECC byte 0</entry>
> -<entry>Error correction code byte 0 of the lower 256 Byte data in
> -this page</entry>
> -</row>
> -<row>
> -<entry>0x01</entry>
> -<entry>ECC byte 1</entry>
> -<entry>Error correction code byte 1 of the lower 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x02</entry>
> -<entry>ECC byte 2</entry>
> -<entry>Error correction code byte 2 of the lower 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x03</entry>
> -<entry>ECC byte 3</entry>
> -<entry>Error correction code byte 0 of the upper 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x04</entry>
> -<entry>reserved</entry>
> -<entry>reserved</entry>
> -</row>
> -<row>
> -<entry>0x05</entry>
> -<entry>Bad block marker</entry>
> -<entry>If any bit in this byte is zero, then this block is bad.
> -This applies only to the first page in a block. In the remaining
> -pages this byte is reserved</entry>
> -</row>
> -<row>
> -<entry>0x06</entry>
> -<entry>ECC byte 4</entry>
> -<entry>Error correction code byte 1 of the upper 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x07</entry>
> -<entry>ECC byte 5</entry>
> -<entry>Error correction code byte 2 of the upper 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x08 - 0x0F</entry>
> -<entry>Autoplace 0 - 7</entry>
> -<entry></entry>
> -</row>
> - </tgroup></informaltable>
> - </sect2>
> - <sect2 id="pagesize_2048">
> - 2048 byte pagesize
> -<informaltable><tgroup cols="3">
> -<row>
> -<entry>Offset</entry>
> -<entry>Content</entry>
> -<entry>Comment</entry>
> -</row>
> -<row>
> -<entry>0x00</entry>
> -<entry>Bad block marker</entry>
> -<entry>If any bit in this byte is zero, then this block is bad.
> -This applies only to the first page in a block. In the remaining
> -pages this byte is reserved</entry>
> -</row>
> -<row>
> -<entry>0x01</entry>
> -<entry>Reserved</entry>
> -<entry>Reserved</entry>
> -</row>
> -<row>
> -<entry>0x02-0x27</entry>
> -<entry>Autoplace 0 - 37</entry>
> -<entry></entry>
> -</row>
> -<row>
> -<entry>0x28</entry>
> -<entry>ECC byte 0</entry>
> -<entry>Error correction code byte 0 of the first 256 Byte data in
> -this page</entry>
> -</row>
> -<row>
> -<entry>0x29</entry>
> -<entry>ECC byte 1</entry>
> -<entry>Error correction code byte 1 of the first 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x2A</entry>
> -<entry>ECC byte 2</entry>
> -<entry>Error correction code byte 2 of the first 256 Bytes data in
> -this page</entry>
> -</row>
> -<row>
> -<entry>0x2B</entry>
> -<entry>ECC byte 3</entry>
> -<entry>Error correction code byte 0 of the second 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x2C</entry>
> -<entry>ECC byte 4</entry>
> -<entry>Error correction code byte 1 of the second 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x2D</entry>
> -<entry>ECC byte 5</entry>
> -<entry>Error correction code byte 2 of the second 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x2E</entry>
> -<entry>ECC byte 6</entry>
> -<entry>Error correction code byte 0 of the third 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x2F</entry>
> -<entry>ECC byte 7</entry>
> -<entry>Error correction code byte 1 of the third 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x30</entry>
> -<entry>ECC byte 8</entry>
> -<entry>Error correction code byte 2 of the third 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x31</entry>
> -<entry>ECC byte 9</entry>
> -<entry>Error correction code byte 0 of the fourth 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x32</entry>
> -<entry>ECC byte 10</entry>
> -<entry>Error correction code byte 1 of the fourth 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x33</entry>
> -<entry>ECC byte 11</entry>
> -<entry>Error correction code byte 2 of the fourth 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x34</entry>
> -<entry>ECC byte 12</entry>
> -<entry>Error correction code byte 0 of the fifth 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x35</entry>
> -<entry>ECC byte 13</entry>
> -<entry>Error correction code byte 1 of the fifth 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x36</entry>
> -<entry>ECC byte 14</entry>
> -<entry>Error correction code byte 2 of the fifth 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x37</entry>
> -<entry>ECC byte 15</entry>
> -<entry>Error correction code byte 0 of the sixt 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x38</entry>
> -<entry>ECC byte 16</entry>
> -<entry>Error correction code byte 1 of the sixt 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x39</entry>
> -<entry>ECC byte 17</entry>
> -<entry>Error correction code byte 2 of the sixt 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x3A</entry>
> -<entry>ECC byte 18</entry>
> -<entry>Error correction code byte 0 of the seventh 256 Bytes of
> -data in this page</entry>
> -</row>
> -<row>
> -<entry>0x3B</entry>
> -<entry>ECC byte 19</entry>
> -<entry>Error correction code byte 1 of the seventh 256 Bytes of
> -data in this page</entry>
> -</row>
> -<row>
> -<entry>0x3C</entry>
> -<entry>ECC byte 20</entry>
> -<entry>Error correction code byte 2 of the seventh 256 Bytes of
> -data in this page</entry>
> -</row>
> -<row>
> -<entry>0x3D</entry>
> -<entry>ECC byte 21</entry>
> -<entry>Error correction code byte 0 of the eighth 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x3E</entry>
> -<entry>ECC byte 22</entry>
> -<entry>Error correction code byte 1 of the eighth 256 Bytes of data
> -in this page</entry>
> -</row>
> -<row>
> -<entry>0x3F</entry>
> -<entry>ECC byte 23</entry>
> -<entry>Error correction code byte 2 of the eighth 256 Bytes of data
> -in this page</entry>
> -</row>
> - </tgroup></informaltable>
> - </sect2>
> - </sect1>
> - </chapter>
> -
> - <chapter id="filesystems">
> - Filesystem support
> -
> - The NAND driver provides all necessary functions for a
> - filesystem via the MTD interface.
> -
> -
> - Filesystems must be aware of the NAND peculiarities and
> - restrictions. One major restrictions of NAND Flash is, that you cannot
> - write as often as you want to a page. The consecutive writes to a page,
> - before erasing it again, are restricted to 1-3 writes, depending on the
> - manufacturers specifications. This applies similar to the spare area.
> -
> -
> - Therefore NAND aware filesystems must either write in page size chunks
> - or hold a writebuffer to collect smaller writes until they sum up to
> - pagesize. Available NAND aware filesystems: JFFS2, YAFFS.
> -
> -
> - The spare area usage to store filesystem data is controlled by
> - the spare area placement functionality which is described in one
> - of the earlier chapters.
> -
> - </chapter>
> - <chapter id="tools">
> - Tools
> -
> - The MTD project provides a couple of helpful tools to handle NAND Flash.
> -
> - flasherase, flasheraseall: Erase and format FLASH partitions
> - nandwrite: write filesystem images to NAND FLASH
> - nanddump: dump the contents of a NAND FLASH partitions
> -
> -
> -
> - These tools are aware of the NAND restrictions. Please use those tools
> - instead of complaining about errors which are caused by non NAND aware
> - access methods.
> -
> - </chapter>
> -
> - <chapter id="defines">
> - Constants
> -
> - This chapter describes the constants which might be relevant for a driver developer.
> -
> - <sect1 id="Chip_option_constants">
> - Chip option constants
> - <sect2 id="Constants_for_chip_id_table">
> - Constants for chip id table
> -
> - These constants are defined in nand.h. They are ored together to describe
> - the chip functionality.
> - <programlisting>
> -/* Buswitdh is 16 bit */
> -#define NAND_BUSWIDTH_16 0x00000002
> -/* Device supports partial programming without padding */
> -#define NAND_NO_PADDING 0x00000004
> -/* Chip has cache program function */
> -#define NAND_CACHEPRG 0x00000008
> -/* Chip has copy back function */
> -#define NAND_COPYBACK 0x00000010
> -/* AND Chip which has 4 banks and a confusing page / block
> - * assignment. See Renesas datasheet for further information */
> -#define NAND_IS_AND 0x00000020
> -/* Chip has a array of 4 pages which can be read without
> - * additional ready /busy waits */
> -#define NAND_4PAGE_ARRAY 0x00000040
> - </programlisting>
> -
> - </sect2>
> - <sect2 id="Constants_for_runtime_options">
> - Constants for runtime options
> -
> - These constants are defined in nand.h. They are ored together to describe
> - the functionality.
> - <programlisting>
> -/* The hw ecc generator provides a syndrome instead a ecc value on read
> - * This can only work if we have the ecc bytes directly behind the
> - * data bytes. Applies for DOC and AG-AND Renesas HW Reed Solomon generators */
> -#define NAND_HWECC_SYNDROME 0x00020000
> - </programlisting>
> -
> - </sect2>
> - </sect1>
> -
> - <sect1 id="EEC_selection_constants">
> - ECC selection constants
> -
> - Use these constants to select the ECC algorithm.
> - <programlisting>
> -/* No ECC. Usage is not recommended ! */
> -#define NAND_ECC_NONE 0
> -/* Software ECC 3 byte ECC per 256 Byte data */
> -#define NAND_ECC_SOFT 1
> -/* Hardware ECC 3 byte ECC per 256 Byte data */
> -#define NAND_ECC_HW3_256 2
> -/* Hardware ECC 3 byte ECC per 512 Byte data */
> -#define NAND_ECC_HW3_512 3
> -/* Hardware ECC 6 byte ECC per 512 Byte data */
> -#define NAND_ECC_HW6_512 4
> -/* Hardware ECC 6 byte ECC per 512 Byte data */
> -#define NAND_ECC_HW8_512 6
> - </programlisting>
> -
> - </sect1>
> -
> - <sect1 id="Hardware_control_related_constants">
> - Hardware control related constants
> -
> - These constants describe the requested hardware access function when
> - the boardspecific hardware control function is called
> - <programlisting>
> -/* Select the chip by setting nCE to low */
> -#define NAND_CTL_SETNCE 1
> -/* Deselect the chip by setting nCE to high */
> -#define NAND_CTL_CLRNCE 2
> -/* Select the command latch by setting CLE to high */
> -#define NAND_CTL_SETCLE 3
> -/* Deselect the command latch by setting CLE to low */
> -#define NAND_CTL_CLRCLE 4
> -/* Select the address latch by setting ALE to high */
> -#define NAND_CTL_SETALE 5
> -/* Deselect the address latch by setting ALE to low */
> -#define NAND_CTL_CLRALE 6
> -/* Set write protection by setting WP to high. Not used! */
> -#define NAND_CTL_SETWP 7
> -/* Clear write protection by setting WP to low. Not used! */
> -#define NAND_CTL_CLRWP 8
> - </programlisting>
> -
> - </sect1>
> -
> - <sect1 id="Bad_block_table_constants">
> - Bad block table related constants
> -
> - These constants describe the options used for bad block
> - table descriptors.
> - <programlisting>
> -/* Options for the bad block table descriptors */
> -
> -/* The number of bits used per block in the bbt on the device */
> -#define NAND_BBT_NRBITS_MSK 0x0000000F
> -#define NAND_BBT_1BIT 0x00000001
> -#define NAND_BBT_2BIT 0x00000002
> -#define NAND_BBT_4BIT 0x00000004
> -#define NAND_BBT_8BIT 0x00000008
> -/* The bad block table is in the last good block of the device */
> -#define NAND_BBT_LASTBLOCK 0x00000010
> -/* The bbt is at the given page, else we must scan for the bbt */
> -#define NAND_BBT_ABSPAGE 0x00000020
> -/* bbt is stored per chip on multichip devices */
> -#define NAND_BBT_PERCHIP 0x00000080
> -/* bbt has a version counter at offset veroffs */
> -#define NAND_BBT_VERSION 0x00000100
> -/* Create a bbt if none axists */
> -#define NAND_BBT_CREATE 0x00000200
> -/* Write bbt if necessary */
> -#define NAND_BBT_WRITE 0x00001000
> -/* Read and write back block contents when writing bbt */
> -#define NAND_BBT_SAVECONTENT 0x00002000
> - </programlisting>
> -
> - </sect1>
> -
> - </chapter>
> -
> - <chapter id="structs">
> - Structures
> -
> - This chapter contains the autogenerated documentation of the structures which are
> - used in the NAND driver and might be relevant for a driver developer. Each
> - struct member has a short description which is marked with an [XXX] identifier.
> - See the chapter "Documentation hints" for an explanation.
> -
> -!Iinclude/linux/mtd/nand.h
> - </chapter>
> -
> - <chapter id="pubfunctions">
> - Public Functions Provided
> -
> - This chapter contains the autogenerated documentation of the NAND kernel API functions
> - which are exported. Each function has a short description which is marked with an [XXX] identifier.
> - See the chapter "Documentation hints" for an explanation.
> -
> -!Edrivers/mtd/nand/nand_base.c
> -!Edrivers/mtd/nand/nand_bbt.c
> -!Edrivers/mtd/nand/nand_ecc.c
> - </chapter>
> -
> - <chapter id="intfunctions">
> - Internal Functions Provided
> -
> - This chapter contains the autogenerated documentation of the NAND driver internal functions.
> - Each function has a short description which is marked with an [XXX] identifier.
> - See the chapter "Documentation hints" for an explanation.
> - The functions marked with [DEFAULT] might be relevant for a board driver developer.
> -
> -!Idrivers/mtd/nand/nand_base.c
> -!Idrivers/mtd/nand/nand_bbt.c
> -<!-- No internal functions for kernel-doc:
> -X!Idrivers/mtd/nand/nand_ecc.c
> --->
> - </chapter>
> -
> - <chapter id="credits">
> - Credits
> -
> - The following people have contributed to the NAND driver:
> -
> - Steven J. Hill<email>sjhill@realitydiluted.com</email>
> - David Woodhouse<email>dwmw2@infradead.org</email>
> - Thomas Gleixner<email>tglx@linutronix.de</email>
> -
> - A lot of users have provided bugfixes, improvements and helping hands for testing.
> - Thanks a lot.
> -
> -
> - The following people have contributed to this document:
> -
> - Thomas Gleixner<email>tglx@linutronix.de</email>
> -
> -
> - </chapter>
> -</book>
> diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst
> index 1f8517db39c7..3cf1acebc4ee 100644
> --- a/Documentation/driver-api/index.rst
> +++ b/Documentation/driver-api/index.rst
> @@ -34,6 +34,7 @@ available subsections can be seen below.
> edac
> scsi
> libata
> + mtdnand
> miscellaneous
> w1
> rapidio
> diff --git a/Documentation/driver-api/mtdnand.rst b/Documentation/driver-api/mtdnand.rst
> new file mode 100644
> index 000000000000..8723175f955e
> --- /dev/null
> +++ b/Documentation/driver-api/mtdnand.rst
> @@ -0,0 +1,1020 @@
> +=====================================
> +MTD NAND Driver Programming Interface
> +=====================================
> +
> +:Author: Thomas Gleixner
> +
> +Introduction
> +============
> +
> +The generic NAND driver supports almost all NAND and AG-AND based chips
> +and connects them to the Memory Technology Devices (MTD) subsystem of
> +the Linux Kernel.
> +
> +This documentation is provided for developers who want to implement
> +board drivers or filesystem drivers suitable for NAND devices.
> +
> +Known Bugs And Assumptions
> +==========================
> +
> +None.
> +
> +Documentation hints
> +===================
> +
> +The function and structure docs are autogenerated. Each function and
> +struct member has a short description which is marked with an [XXX]
> +identifier. The following chapters explain the meaning of those
> +identifiers.
> +
> +Function identifiers [XXX]
> +--------------------------
> +
> +The functions are marked with [XXX] identifiers in the short comment.
> +The identifiers explain the usage and scope of the functions. Following
> +identifiers are used:
> +
> +- [MTD Interface]
> +
> + These functions provide the interface to the MTD kernel API. They are
> + not replaceable and provide functionality which is complete hardware
> + independent.
> +
> +- [NAND Interface]
> +
> + These functions are exported and provide the interface to the NAND
> + kernel API.
> +
> +- [GENERIC]
> +
> + Generic functions are not replaceable and provide functionality which
> + is complete hardware independent.
> +
> +- [DEFAULT]
> +
> + Default functions provide hardware related functionality which is
> + suitable for most of the implementations. These functions can be
> + replaced by the board driver if necessary. Those functions are called
> + via pointers in the NAND chip description structure. The board driver
> + can set the functions which should be replaced by board dependent
> + functions before calling nand_scan(). If the function pointer is
> + NULL on entry to nand_scan() then the pointer is set to the default
> + function which is suitable for the detected chip type.
> +
> +Struct member identifiers [XXX]
> +-------------------------------
> +
> +The struct members are marked with [XXX] identifiers in the comment. The
> +identifiers explain the usage and scope of the members. Following
> +identifiers are used:
> +
> +- [INTERN]
> +
> + These members are for NAND driver internal use only and must not be
> + modified. Most of these values are calculated from the chip geometry
> + information which is evaluated during nand_scan().
> +
> +- [REPLACEABLE]
> +
> + Replaceable members hold hardware related functions which can be
> + provided by the board driver. The board driver can set the functions
> + which should be replaced by board dependent functions before calling
> + nand_scan(). If the function pointer is NULL on entry to
> + nand_scan() then the pointer is set to the default function which is
> + suitable for the detected chip type.
> +
> +- [BOARDSPECIFIC]
> +
> + Board specific members hold hardware related information which must
> + be provided by the board driver. The board driver must set the
> + function pointers and datafields before calling nand_scan().
> +
> +- [OPTIONAL]
> +
> + Optional members can hold information relevant for the board driver.
> + The generic NAND driver code does not use this information.
> +
> +Basic board driver
> +==================
> +
> +For most boards it will be sufficient to provide just the basic
> +functions and fill out some really board dependent members in the nand
> +chip description structure.
> +
> +Basic defines
> +-------------
> +
> +At least you have to provide a nand_chip structure and a storage for
> +the ioremap'ed chip address. You can allocate the nand_chip structure
> +using kmalloc or you can allocate it statically. The NAND chip structure
> +embeds an mtd structure which will be registered to the MTD subsystem.
> +You can extract a pointer to the mtd structure from a nand_chip pointer
> +using the nand_to_mtd() helper.
> +
> +Kmalloc based example
> +
> +::
> +
> + static struct mtd_info *board_mtd;
> + static void __iomem *baseaddr;
> +
> +
> +Static example
> +
> +::
> +
> + static struct nand_chip board_chip;
> + static void __iomem *baseaddr;
> +
> +
> +Partition defines
> +-----------------
> +
> +If you want to divide your device into partitions, then define a
> +partitioning scheme suitable to your board.
> +
> +::
> +
> + #define NUM_PARTITIONS 2
> + static struct mtd_partition partition_info[] = {
> + { .name = "Flash partition 1",
> + .offset = 0,
> + .size = 8 * 1024 * 1024 },
> + { .name = "Flash partition 2",
> + .offset = MTDPART_OFS_NEXT,
> + .size = MTDPART_SIZ_FULL },
> + };
> +
> +
> +Hardware control function
> +-------------------------
> +
> +The hardware control function provides access to the control pins of the
> +NAND chip(s). The access can be done by GPIO pins or by address lines.
> +If you use address lines, make sure that the timing requirements are
> +met.
> +
> +*GPIO based example*
> +
> +::
> +
> + static void board_hwcontrol(struct mtd_info *mtd, int cmd)
> + {
> + switch(cmd){
> + case NAND_CTL_SETCLE: /* Set CLE pin high */ break;
> + case NAND_CTL_CLRCLE: /* Set CLE pin low */ break;
> + case NAND_CTL_SETALE: /* Set ALE pin high */ break;
> + case NAND_CTL_CLRALE: /* Set ALE pin low */ break;
> + case NAND_CTL_SETNCE: /* Set nCE pin low */ break;
> + case NAND_CTL_CLRNCE: /* Set nCE pin high */ break;
> + }
> + }
> +
> +
> +*Address lines based example.* It's assumed that the nCE pin is driven
> +by a chip select decoder.
> +
> +::
> +
> + static void board_hwcontrol(struct mtd_info *mtd, int cmd)
> + {
> + struct nand_chip *this = mtd_to_nand(mtd);
> + switch(cmd){
> + case NAND_CTL_SETCLE: this->IO_ADDR_W |= CLE_ADRR_BIT; break;
> + case NAND_CTL_CLRCLE: this->IO_ADDR_W &= ~CLE_ADRR_BIT; break;
> + case NAND_CTL_SETALE: this->IO_ADDR_W |= ALE_ADRR_BIT; break;
> + case NAND_CTL_CLRALE: this->IO_ADDR_W &= ~ALE_ADRR_BIT; break;
> + }
> + }
> +
> +
> +Device ready function
> +---------------------
> +
> +If the hardware interface has the ready busy pin of the NAND chip
> +connected to a GPIO or other accessible I/O pin, this function is used
> +to read back the state of the pin. The function has no arguments and
> +should return 0, if the device is busy (R/B pin is low) and 1, if the
> +device is ready (R/B pin is high). If the hardware interface does not
> +give access to the ready busy pin, then the function must not be defined
> +and the function pointer this->dev_ready is set to NULL.
> +
> +Init function
> +-------------
> +
> +The init function allocates memory and sets up all the board specific
> +parameters and function pointers. When everything is set up nand_scan()
> +is called. This function tries to detect and identify then chip. If a
> +chip is found all the internal data fields are initialized accordingly.
> +The structure(s) have to be zeroed out first and then filled with the
> +necessary information about the device.
> +
> +::
> +
> + static int __init board_init (void)
> + {
> + struct nand_chip *this;
> + int err = 0;
> +
> + /* Allocate memory for MTD device structure and private data */
> + this = kzalloc(sizeof(struct nand_chip), GFP_KERNEL);
> + if (!this) {
> + printk ("Unable to allocate NAND MTD device structure.\n");
> + err = -ENOMEM;
> + goto out;
> + }
> +
> + board_mtd = nand_to_mtd(this);
> +
> + /* map physical address */
> + baseaddr = ioremap(CHIP_PHYSICAL_ADDRESS, 1024);
> + if (!baseaddr) {
> + printk("Ioremap to access NAND chip failed\n");
> + err = -EIO;
> + goto out_mtd;
> + }
> +
> + /* Set address of NAND IO lines */
> + this->IO_ADDR_R = baseaddr;
> + this->IO_ADDR_W = baseaddr;
> + /* Reference hardware control function */
> + this->hwcontrol = board_hwcontrol;
> + /* Set command delay time, see datasheet for correct value */
> + this->chip_delay = CHIP_DEPENDEND_COMMAND_DELAY;
> + /* Assign the device ready function, if available */
> + this->dev_ready = board_dev_ready;
> + this->eccmode = NAND_ECC_SOFT;
> +
> + /* Scan to find existence of the device */
> + if (nand_scan (board_mtd, 1)) {
> + err = -ENXIO;
> + goto out_ior;
> + }
> +
> + add_mtd_partitions(board_mtd, partition_info, NUM_PARTITIONS);
> + goto out;
> +
> + out_ior:
> + iounmap(baseaddr);
> + out_mtd:
> + kfree (this);
> + out:
> + return err;
> + }
> + module_init(board_init);
> +
> +
> +Exit function
> +-------------
> +
> +The exit function is only necessary if the driver is compiled as a
> +module. It releases all resources which are held by the chip driver and
> +unregisters the partitions in the MTD layer.
> +
> +::
> +
> + #ifdef MODULE
> + static void __exit board_cleanup (void)
> + {
> + /* Release resources, unregister device */
> + nand_release (board_mtd);
> +
> + /* unmap physical address */
> + iounmap(baseaddr);
> +
> + /* Free the MTD device structure */
> + kfree (mtd_to_nand(board_mtd));
> + }
> + module_exit(board_cleanup);
> + #endif
> +
> +
> +Advanced board driver functions
> +===============================
> +
> +This chapter describes the advanced functionality of the NAND driver.
> +For a list of functions which can be overridden by the board driver see
> +the documentation of the nand_chip structure.
> +
> +Multiple chip control
> +---------------------
> +
> +The nand driver can control chip arrays. Therefore the board driver must
> +provide an own select_chip function. This function must (de)select the
> +requested chip. The function pointer in the nand_chip structure must be
> +set before calling nand_scan(). The maxchip parameter of nand_scan()
> +defines the maximum number of chips to scan for. Make sure that the
> +select_chip function can handle the requested number of chips.
> +
> +The nand driver concatenates the chips to one virtual chip and provides
> +this virtual chip to the MTD layer.
> +
> +*Note: The driver can only handle linear chip arrays of equally sized
> +chips. There is no support for parallel arrays which extend the
> +buswidth.*
> +
> +*GPIO based example*
> +
> +::
> +
> + static void board_select_chip (struct mtd_info *mtd, int chip)
> + {
> + /* Deselect all chips, set all nCE pins high */
> + GPIO(BOARD_NAND_NCE) |= 0xff;
> + if (chip >= 0)
> + GPIO(BOARD_NAND_NCE) &= ~ (1 << chip);
> + }
> +
> +
> +*Address lines based example.* Its assumed that the nCE pins are
> +connected to an address decoder.
> +
> +::
> +
> + static void board_select_chip (struct mtd_info *mtd, int chip)
> + {
> + struct nand_chip *this = mtd_to_nand(mtd);
> +
> + /* Deselect all chips */
> + this->IO_ADDR_R &= ~BOARD_NAND_ADDR_MASK;
> + this->IO_ADDR_W &= ~BOARD_NAND_ADDR_MASK;
> + switch (chip) {
> + case 0:
> + this->IO_ADDR_R |= BOARD_NAND_ADDR_CHIP0;
> + this->IO_ADDR_W |= BOARD_NAND_ADDR_CHIP0;
> + break;
> + ....
> + case n:
> + this->IO_ADDR_R |= BOARD_NAND_ADDR_CHIPn;
> + this->IO_ADDR_W |= BOARD_NAND_ADDR_CHIPn;
> + break;
> + }
> + }
> +
> +
> +Hardware ECC support
> +--------------------
> +
> +Functions and constants
> +~~~~~~~~~~~~~~~~~~~~~~~
> +
> +The nand driver supports three different types of hardware ECC.
> +
> +- NAND_ECC_HW3_256
> +
> + Hardware ECC generator providing 3 bytes ECC per 256 byte.
> +
> +- NAND_ECC_HW3_512
> +
> + Hardware ECC generator providing 3 bytes ECC per 512 byte.
> +
> +- NAND_ECC_HW6_512
> +
> + Hardware ECC generator providing 6 bytes ECC per 512 byte.
> +
> +- NAND_ECC_HW8_512
> +
> + Hardware ECC generator providing 6 bytes ECC per 512 byte.
> +
> +If your hardware generator has a different functionality add it at the
> +appropriate place in nand_base.c
> +
> +The board driver must provide following functions:
> +
> +- enable_hwecc
> +
> + This function is called before reading / writing to the chip. Reset
> + or initialize the hardware generator in this function. The function
> + is called with an argument which let you distinguish between read and
> + write operations.
> +
> +- calculate_ecc
> +
> + This function is called after read / write from / to the chip.
> + Transfer the ECC from the hardware to the buffer. If the option
> + NAND_HWECC_SYNDROME is set then the function is only called on
> + write. See below.
> +
> +- correct_data
> +
> + In case of an ECC error this function is called for error detection
> + and correction. Return 1 respectively 2 in case the error can be
> + corrected. If the error is not correctable return -1. If your
> + hardware generator matches the default algorithm of the nand_ecc
> + software generator then use the correction function provided by
> + nand_ecc instead of implementing duplicated code.
> +
> +Hardware ECC with syndrome calculation
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +Many hardware ECC implementations provide Reed-Solomon codes and
> +calculate an error syndrome on read. The syndrome must be converted to a
> +standard Reed-Solomon syndrome before calling the error correction code
> +in the generic Reed-Solomon library.
> +
> +The ECC bytes must be placed immediately after the data bytes in order
> +to make the syndrome generator work. This is contrary to the usual
> +layout used by software ECC. The separation of data and out of band area
> +is not longer possible. The nand driver code handles this layout and the
> +remaining free bytes in the oob area are managed by the autoplacement
> +code. Provide a matching oob-layout in this case. See rts_from4.c and
> +diskonchip.c for implementation reference. In those cases we must also
> +use bad block tables on FLASH, because the ECC layout is interfering
> +with the bad block marker positions. See bad block table support for
> +details.
> +
> +Bad block table support
> +-----------------------
> +
> +Most NAND chips mark the bad blocks at a defined position in the spare
> +area. Those blocks must not be erased under any circumstances as the bad
> +block information would be lost. It is possible to check the bad block
> +mark each time when the blocks are accessed by reading the spare area of
> +the first page in the block. This is time consuming so a bad block table
> +is used.
> +
> +The nand driver supports various types of bad block tables.
> +
> +- Per device
> +
> + The bad block table contains all bad block information of the device
> + which can consist of multiple chips.
> +
> +- Per chip
> +
> + A bad block table is used per chip and contains the bad block
> + information for this particular chip.
> +
> +- Fixed offset
> +
> + The bad block table is located at a fixed offset in the chip
> + (device). This applies to various DiskOnChip devices.
> +
> +- Automatic placed
> +
> + The bad block table is automatically placed and detected either at
> + the end or at the beginning of a chip (device)
> +
> +- Mirrored tables
> +
> + The bad block table is mirrored on the chip (device) to allow updates
> + of the bad block table without data loss.
> +
> +nand_scan() calls the function nand_default_bbt().
> +nand_default_bbt() selects appropriate default bad block table
> +descriptors depending on the chip information which was retrieved by
> +nand_scan().
> +
> +The standard policy is scanning the device for bad blocks and build a
> +ram based bad block table which allows faster access than always
> +checking the bad block information on the flash chip itself.
> +
> +Flash based tables
> +~~~~~~~~~~~~~~~~~~
> +
> +It may be desired or necessary to keep a bad block table in FLASH. For
> +AG-AND chips this is mandatory, as they have no factory marked bad
> +blocks. They have factory marked good blocks. The marker pattern is
> +erased when the block is erased to be reused. So in case of powerloss
> +before writing the pattern back to the chip this block would be lost and
> +added to the bad blocks. Therefore we scan the chip(s) when we detect
> +them the first time for good blocks and store this information in a bad
> +block table before erasing any of the blocks.
> +
> +The blocks in which the tables are stored are protected against
> +accidental access by marking them bad in the memory bad block table. The
> +bad block table management functions are allowed to circumvent this
> +protection.
> +
> +The simplest way to activate the FLASH based bad block table support is
> +to set the option NAND_BBT_USE_FLASH in the bbt_option field of the
> +nand chip structure before calling nand_scan(). For AG-AND chips is
> +this done by default. This activates the default FLASH based bad block
> +table functionality of the NAND driver. The default bad block table
> +options are
> +
> +- Store bad block table per chip
> +
> +- Use 2 bits per block
> +
> +- Automatic placement at the end of the chip
> +
> +- Use mirrored tables with version numbers
> +
> +- Reserve 4 blocks at the end of the chip
> +
> +User defined tables
> +~~~~~~~~~~~~~~~~~~~
> +
> +User defined tables are created by filling out a nand_bbt_descr
> +structure and storing the pointer in the nand_chip structure member
> +bbt_td before calling nand_scan(). If a mirror table is necessary a
> +second structure must be created and a pointer to this structure must be
> +stored in bbt_md inside the nand_chip structure. If the bbt_md member
> +is set to NULL then only the main table is used and no scan for the
> +mirrored table is performed.
> +
> +The most important field in the nand_bbt_descr structure is the
> +options field. The options define most of the table properties. Use the
> +predefined constants from nand.h to define the options.
> +
> +- Number of bits per block
> +
> + The supported number of bits is 1, 2, 4, 8.
> +
> +- Table per chip
> +
> + Setting the constant NAND_BBT_PERCHIP selects that a bad block
> + table is managed for each chip in a chip array. If this option is not
> + set then a per device bad block table is used.
> +
> +- Table location is absolute
> +
> + Use the option constant NAND_BBT_ABSPAGE and define the absolute
> + page number where the bad block table starts in the field pages. If
> + you have selected bad block tables per chip and you have a multi chip
> + array then the start page must be given for each chip in the chip
> + array. Note: there is no scan for a table ident pattern performed, so
> + the fields pattern, veroffs, offs, len can be left uninitialized
> +
> +- Table location is automatically detected
> +
> + The table can either be located in the first or the last good blocks
> + of the chip (device). Set NAND_BBT_LASTBLOCK to place the bad block
> + table at the end of the chip (device). The bad block tables are
> + marked and identified by a pattern which is stored in the spare area
> + of the first page in the block which holds the bad block table. Store
> + a pointer to the pattern in the pattern field. Further the length of
> + the pattern has to be stored in len and the offset in the spare area
> + must be given in the offs member of the nand_bbt_descr structure.
> + For mirrored bad block tables different patterns are mandatory.
> +
> +- Table creation
> +
> + Set the option NAND_BBT_CREATE to enable the table creation if no
> + table can be found during the scan. Usually this is done only once if
> + a new chip is found.
> +
> +- Table write support
> +
> + Set the option NAND_BBT_WRITE to enable the table write support.
> + This allows the update of the bad block table(s) in case a block has
> + to be marked bad due to wear. The MTD interface function
> + block_markbad is calling the update function of the bad block table.
> + If the write support is enabled then the table is updated on FLASH.
> +
> + Note: Write support should only be enabled for mirrored tables with
> + version control.
> +
> +- Table version control
> +
> + Set the option NAND_BBT_VERSION to enable the table version
> + control. It's highly recommended to enable this for mirrored tables
> + with write support. It makes sure that the risk of losing the bad
> + block table information is reduced to the loss of the information
> + about the one worn out block which should be marked bad. The version
> + is stored in 4 consecutive bytes in the spare area of the device. The
> + position of the version number is defined by the member veroffs in
> + the bad block table descriptor.
> +
> +- Save block contents on write
> +
> + In case that the block which holds the bad block table does contain
> + other useful information, set the option NAND_BBT_SAVECONTENT. When
> + the bad block table is written then the whole block is read the bad
> + block table is updated and the block is erased and everything is
> + written back. If this option is not set only the bad block table is
> + written and everything else in the block is ignored and erased.
> +
> +- Number of reserved blocks
> +
> + For automatic placement some blocks must be reserved for bad block
> + table storage. The number of reserved blocks is defined in the
> + maxblocks member of the bad block table description structure.
> + Reserving 4 blocks for mirrored tables should be a reasonable number.
> + This also limits the number of blocks which are scanned for the bad
> + block table ident pattern.
> +
> +Spare area (auto)placement
> +--------------------------
> +
> +The nand driver implements different possibilities for placement of
> +filesystem data in the spare area,
> +
> +- Placement defined by fs driver
> +
> +- Automatic placement
> +
> +The default placement function is automatic placement. The nand driver
> +has built in default placement schemes for the various chiptypes. If due
> +to hardware ECC functionality the default placement does not fit then
> +the board driver can provide a own placement scheme.
> +
> +File system drivers can provide a own placement scheme which is used
> +instead of the default placement scheme.
> +
> +Placement schemes are defined by a nand_oobinfo structure
> +
> +::
> +
> + struct nand_oobinfo {
> + int useecc;
> + int eccbytes;
> + int eccpos[24];
> + int oobfree[8][2];
> + };
> +
> +
> +- useecc
> +
> + The useecc member controls the ecc and placement function. The header
> + file include/mtd/mtd-abi.h contains constants to select ecc and
> + placement. MTD_NANDECC_OFF switches off the ecc complete. This is
> + not recommended and available for testing and diagnosis only.
> + MTD_NANDECC_PLACE selects caller defined placement,
> + MTD_NANDECC_AUTOPLACE selects automatic placement.
> +
> +- eccbytes
> +
> + The eccbytes member defines the number of ecc bytes per page.
> +
> +- eccpos
> +
> + The eccpos array holds the byte offsets in the spare area where the
> + ecc codes are placed.
> +
> +- oobfree
> +
> + The oobfree array defines the areas in the spare area which can be
> + used for automatic placement. The information is given in the format
> + {offset, size}. offset defines the start of the usable area, size the
> + length in bytes. More than one area can be defined. The list is
> + terminated by an {0, 0} entry.
> +
> +Placement defined by fs driver
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +The calling function provides a pointer to a nand_oobinfo structure
> +which defines the ecc placement. For writes the caller must provide a
> +spare area buffer along with the data buffer. The spare area buffer size
> +is (number of pages) \* (size of spare area). For reads the buffer size
> +is (number of pages) \* ((size of spare area) + (number of ecc steps per
> +page) \* sizeof (int)). The driver stores the result of the ecc check
> +for each tuple in the spare buffer. The storage sequence is::
> +
> + <spare data page 0><ecc result 0>...<ecc result n>
> +
> + ...
> +
> + <spare data page n><ecc result 0>...<ecc result n>
> +
> +This is a legacy mode used by YAFFS1.
> +
> +If the spare area buffer is NULL then only the ECC placement is done
> +according to the given scheme in the nand_oobinfo structure.
> +
> +Automatic placement
> +~~~~~~~~~~~~~~~~~~~
> +
> +Automatic placement uses the built in defaults to place the ecc bytes in
> +the spare area. If filesystem data have to be stored / read into the
> +spare area then the calling function must provide a buffer. The buffer
> +size per page is determined by the oobfree array in the nand_oobinfo
> +structure.
> +
> +If the spare area buffer is NULL then only the ECC placement is done
> +according to the default builtin scheme.
> +
> +Spare area autoplacement default schemes
> +----------------------------------------
> +
> +256 byte pagesize
> +~~~~~~~~~~~~~~~~~
> +
> +======== ================== ===================================================
> +Offset Content Comment
> +======== ================== ===================================================
> +0x00 ECC byte 0 Error correction code byte 0
> +0x01 ECC byte 1 Error correction code byte 1
> +0x02 ECC byte 2 Error correction code byte 2
> +0x03 Autoplace 0
> +0x04 Autoplace 1
> +0x05 Bad block marker If any bit in this byte is zero, then this
> + block is bad. This applies only to the first
> + page in a block. In the remaining pages this
> + byte is reserved
> +0x06 Autoplace 2
> +0x07 Autoplace 3
> +======== ================== ===================================================
> +
> +512 byte pagesize
> +~~~~~~~~~~~~~~~~~
> +
> +
> +============= ================== ==============================================
> +Offset Content Comment
> +============= ================== ==============================================
> +0x00 ECC byte 0 Error correction code byte 0 of the lower
> + 256 Byte data in this page
> +0x01 ECC byte 1 Error correction code byte 1 of the lower
> + 256 Bytes of data in this page
> +0x02 ECC byte 2 Error correction code byte 2 of the lower
> + 256 Bytes of data in this page
> +0x03 ECC byte 3 Error correction code byte 0 of the upper
> + 256 Bytes of data in this page
> +0x04 reserved reserved
> +0x05 Bad block marker If any bit in this byte is zero, then this
> + block is bad. This applies only to the first
> + page in a block. In the remaining pages this
> + byte is reserved
> +0x06 ECC byte 4 Error correction code byte 1 of the upper
> + 256 Bytes of data in this page
> +0x07 ECC byte 5 Error correction code byte 2 of the upper
> + 256 Bytes of data in this page
> +0x08 - 0x0F Autoplace 0 - 7
> +============= ================== ==============================================
> +
> +2048 byte pagesize
> +~~~~~~~~~~~~~~~~~~
> +
> +=========== ================== ================================================
> +Offset Content Comment
> +=========== ================== ================================================
> +0x00 Bad block marker If any bit in this byte is zero, then this block
> + is bad. This applies only to the first page in a
> + block. In the remaining pages this byte is
> + reserved
> +0x01 Reserved Reserved
> +0x02-0x27 Autoplace 0 - 37
> +0x28 ECC byte 0 Error correction code byte 0 of the first
> + 256 Byte data in this page
> +0x29 ECC byte 1 Error correction code byte 1 of the first
> + 256 Bytes of data in this page
> +0x2A ECC byte 2 Error correction code byte 2 of the first
> + 256 Bytes data in this page
> +0x2B ECC byte 3 Error correction code byte 0 of the second
> + 256 Bytes of data in this page
> +0x2C ECC byte 4 Error correction code byte 1 of the second
> + 256 Bytes of data in this page
> +0x2D ECC byte 5 Error correction code byte 2 of the second
> + 256 Bytes of data in this page
> +0x2E ECC byte 6 Error correction code byte 0 of the third
> + 256 Bytes of data in this page
> +0x2F ECC byte 7 Error correction code byte 1 of the third
> + 256 Bytes of data in this page
> +0x30 ECC byte 8 Error correction code byte 2 of the third
> + 256 Bytes of data in this page
> +0x31 ECC byte 9 Error correction code byte 0 of the fourth
> + 256 Bytes of data in this page
> +0x32 ECC byte 10 Error correction code byte 1 of the fourth
> + 256 Bytes of data in this page
> +0x33 ECC byte 11 Error correction code byte 2 of the fourth
> + 256 Bytes of data in this page
> +0x34 ECC byte 12 Error correction code byte 0 of the fifth
> + 256 Bytes of data in this page
> +0x35 ECC byte 13 Error correction code byte 1 of the fifth
> + 256 Bytes of data in this page
> +0x36 ECC byte 14 Error correction code byte 2 of the fifth
> + 256 Bytes of data in this page
> +0x37 ECC byte 15 Error correction code byte 0 of the sixth
> + 256 Bytes of data in this page
> +0x38 ECC byte 16 Error correction code byte 1 of the sixth
> + 256 Bytes of data in this page
> +0x39 ECC byte 17 Error correction code byte 2 of the sixth
> + 256 Bytes of data in this page
> +0x3A ECC byte 18 Error correction code byte 0 of the seventh
> + 256 Bytes of data in this page
> +0x3B ECC byte 19 Error correction code byte 1 of the seventh
> + 256 Bytes of data in this page
> +0x3C ECC byte 20 Error correction code byte 2 of the seventh
> + 256 Bytes of data in this page
> +0x3D ECC byte 21 Error correction code byte 0 of the eighth
> + 256 Bytes of data in this page
> +0x3E ECC byte 22 Error correction code byte 1 of the eighth
> + 256 Bytes of data in this page
> +0x3F ECC byte 23 Error correction code byte 2 of the eighth
> + 256 Bytes of data in this page
> +=========== ================== ================================================
> +
> +Filesystem support
> +==================
> +
> +The NAND driver provides all necessary functions for a filesystem via
> +the MTD interface.
> +
> +Filesystems must be aware of the NAND peculiarities and restrictions.
> +One major restrictions of NAND Flash is, that you cannot write as often
> +as you want to a page. The consecutive writes to a page, before erasing
> +it again, are restricted to 1-3 writes, depending on the manufacturers
> +specifications. This applies similar to the spare area.
> +
> +Therefore NAND aware filesystems must either write in page size chunks
> +or hold a writebuffer to collect smaller writes until they sum up to
> +pagesize. Available NAND aware filesystems: JFFS2, YAFFS.
> +
> +The spare area usage to store filesystem data is controlled by the spare
> +area placement functionality which is described in one of the earlier
> +chapters.
> +
> +Tools
> +=====
> +
> +The MTD project provides a couple of helpful tools to handle NAND Flash.
> +
> +- flasherase, flasheraseall: Erase and format FLASH partitions
> +
> +- nandwrite: write filesystem images to NAND FLASH
> +
> +- nanddump: dump the contents of a NAND FLASH partitions
> +
> +These tools are aware of the NAND restrictions. Please use those tools
> +instead of complaining about errors which are caused by non NAND aware
> +access methods.
> +
> +Constants
> +=========
> +
> +This chapter describes the constants which might be relevant for a
> +driver developer.
> +
> +Chip option constants
> +---------------------
> +
> +Constants for chip id table
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +These constants are defined in nand.h. They are ored together to
> +describe the chip functionality.
> +
> +::
> +
> + /* Buswitdh is 16 bit */
> + #define NAND_BUSWIDTH_16 0x00000002
> + /* Device supports partial programming without padding */
> + #define NAND_NO_PADDING 0x00000004
> + /* Chip has cache program function */
> + #define NAND_CACHEPRG 0x00000008
> + /* Chip has copy back function */
> + #define NAND_COPYBACK 0x00000010
> + /* AND Chip which has 4 banks and a confusing page / block
> + * assignment. See Renesas datasheet for further information */
> + #define NAND_IS_AND 0x00000020
> + /* Chip has a array of 4 pages which can be read without
> + * additional ready /busy waits */
> + #define NAND_4PAGE_ARRAY 0x00000040
> +
> +
> +Constants for runtime options
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +
> +These constants are defined in nand.h. They are ored together to
> +describe the functionality.
> +
> +::
> +
> + /* The hw ecc generator provides a syndrome instead a ecc value on read
> + * This can only work if we have the ecc bytes directly behind the
> + * data bytes. Applies for DOC and AG-AND Renesas HW Reed Solomon generators */
> + #define NAND_HWECC_SYNDROME 0x00020000
> +
> +
> +ECC selection constants
> +-----------------------
> +
> +Use these constants to select the ECC algorithm.
> +
> +::
> +
> + /* No ECC. Usage is not recommended ! */
> + #define NAND_ECC_NONE 0
> + /* Software ECC 3 byte ECC per 256 Byte data */
> + #define NAND_ECC_SOFT 1
> + /* Hardware ECC 3 byte ECC per 256 Byte data */
> + #define NAND_ECC_HW3_256 2
> + /* Hardware ECC 3 byte ECC per 512 Byte data */
> + #define NAND_ECC_HW3_512 3
> + /* Hardware ECC 6 byte ECC per 512 Byte data */
> + #define NAND_ECC_HW6_512 4
> + /* Hardware ECC 6 byte ECC per 512 Byte data */
> + #define NAND_ECC_HW8_512 6
> +
> +
> +Hardware control related constants
> +----------------------------------
> +
> +These constants describe the requested hardware access function when the
> +boardspecific hardware control function is called
> +
> +::
> +
> + /* Select the chip by setting nCE to low */
> + #define NAND_CTL_SETNCE 1
> + /* Deselect the chip by setting nCE to high */
> + #define NAND_CTL_CLRNCE 2
> + /* Select the command latch by setting CLE to high */
> + #define NAND_CTL_SETCLE 3
> + /* Deselect the command latch by setting CLE to low */
> + #define NAND_CTL_CLRCLE 4
> + /* Select the address latch by setting ALE to high */
> + #define NAND_CTL_SETALE 5
> + /* Deselect the address latch by setting ALE to low */
> + #define NAND_CTL_CLRALE 6
> + /* Set write protection by setting WP to high. Not used! */
> + #define NAND_CTL_SETWP 7
> + /* Clear write protection by setting WP to low. Not used! */
> + #define NAND_CTL_CLRWP 8
> +
> +
> +Bad block table related constants
> +---------------------------------
> +
> +These constants describe the options used for bad block table
> +descriptors.
> +
> +::
> +
> + /* Options for the bad block table descriptors */
> +
> + /* The number of bits used per block in the bbt on the device */
> + #define NAND_BBT_NRBITS_MSK 0x0000000F
> + #define NAND_BBT_1BIT 0x00000001
> + #define NAND_BBT_2BIT 0x00000002
> + #define NAND_BBT_4BIT 0x00000004
> + #define NAND_BBT_8BIT 0x00000008
> + /* The bad block table is in the last good block of the device */
> + #define NAND_BBT_LASTBLOCK 0x00000010
> + /* The bbt is at the given page, else we must scan for the bbt */
> + #define NAND_BBT_ABSPAGE 0x00000020
> + /* bbt is stored per chip on multichip devices */
> + #define NAND_BBT_PERCHIP 0x00000080
> + /* bbt has a version counter at offset veroffs */
> + #define NAND_BBT_VERSION 0x00000100
> + /* Create a bbt if none axists */
> + #define NAND_BBT_CREATE 0x00000200
> + /* Write bbt if necessary */
> + #define NAND_BBT_WRITE 0x00001000
> + /* Read and write back block contents when writing bbt */
> + #define NAND_BBT_SAVECONTENT 0x00002000
> +
> +
> +Structures
> +==========
> +
> +This chapter contains the autogenerated documentation of the structures
> +which are used in the NAND driver and might be relevant for a driver
> +developer. Each struct member has a short description which is marked
> +with an [XXX] identifier. See the chapter "Documentation hints" for an
> +explanation.
> +
> +.. kernel-doc:: include/linux/mtd/nand.h
> + :internal:
> +
> +Public Functions Provided
> +=========================
> +
> +This chapter contains the autogenerated documentation of the NAND kernel
> +API functions which are exported. Each function has a short description
> +which is marked with an [XXX] identifier. See the chapter "Documentation
> +hints" for an explanation.
> +
> +.. kernel-doc:: drivers/mtd/nand/nand_base.c
> + :export:
> +
> +.. kernel-doc:: drivers/mtd/nand/nand_bbt.c
> + :export:
> +
> +.. kernel-doc:: drivers/mtd/nand/nand_ecc.c
> + :export:
> +
> +Internal Functions Provided
> +===========================
> +
> +This chapter contains the autogenerated documentation of the NAND driver
> +internal functions. Each function has a short description which is
> +marked with an [XXX] identifier. See the chapter "Documentation hints"
> +for an explanation. The functions marked with [DEFAULT] might be
> +relevant for a board driver developer.
> +
> +.. kernel-doc:: drivers/mtd/nand/nand_base.c
> + :internal:
> +
> +.. kernel-doc:: drivers/mtd/nand/nand_bbt.c
> + :internal:
> +
> +Credits
> +=======
> +
> +The following people have contributed to the NAND driver:
> +
> +1. Steven J. Hill\ sjhill@realitydiluted.com
> +
> +2. David Woodhouse\ dwmw2@infradead.org
> +
> +3. Thomas Gleixner\ tglx@linutronix.de
> +
> +A lot of users have provided bugfixes, improvements and helping hands
> +for testing. Thanks a lot.
> +
> +The following people have contributed to this document:
> +
> +1. Thomas Gleixner\ tglx@linutronix.de