查看“MTD overview”的源代码

'''SUMMARY '''<br>
MTD（内存技术设备）子系统为原始闪存提供抽象层。 在使用不同的Flash类型和技术（例如，Flash）时，可以使用相同的API。 SLC NAND，SPI NOR，...

== Framework purpose ==
本文的目的是介绍MTD Linux子系统：
* 一般信息
* 主要组成部分/利益相关者
* 如何使用MTD API

==System overview==

[[File:MTD v1.1.0.png|center]]

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[[File:mtd.png|center]]
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===Component description===
* 执行“文件I / O”的用户空间应用程序需要像对待磁盘一样查看闪存，而希望完成“原始I / O”的程序就像访问磁盘一样访问该存储器。 是一个角色设备。

* '''VFS''' (内核空间)
虚拟文件系统。 请参考VFS文档 <ref>{{CodeSource | Linux kernel | Documentation/filesystems/vfs.txt | VFS}} </ref>.

* '''mtdchar''' (内核空间)
通常称为/ dev / mtdX。 对于MTD字符设备，请参考MTD概述文档 <ref>[http://www.linux-mtd.infradead.org/doc/general.html#L_overview MTD overview]</ref>.

* '''mtdblock''' (内核空间)
通常称为/ dev / mtdblockX。 除非您确切知道自己在做什么，否则不要使用mtdblock。 对于MTD块设备，请参考MTD块文档<ref>[http://www.linux-mtd.infradead.org/doc/general.html#L_mtdblock MTD block]</ref>.

* '''JFFS2''' (内核空间)
日记Flash文件系统。 请参考MTD JFFS2文档 <ref>[http://www.linux-mtd.infradead.org/doc/jffs2.html MTD JFFS2]</ref>.

* '''UBI''' (内核空间)
未分类的块图像。 请参考MTD UBI文档 <ref>[http://www.linux-mtd.infradead.org/doc/ubi.html MTD UBI]</ref>.

* '''UBIFS''' (内核空间)
UBI文件系统。 请参考MTD UBIFS文档<ref>[http://www.linux-mtd.infradead.org/doc/ubifs.html MTD UBIFS]</ref>.

* '''MTD core''' (内核空间)
MTD内核为原始闪存提供了一个抽象层。

* '''Raw NAND subsystem''' (内核空间)
MTD子系统中使用Raw NAND协议来连接NAND闪存。

* '''SPI-MEM subsystem''' (内核空间)
SPI-MEM协议在MTD子系统中用于连接各种SPI存储器（NOR，NAND）

* '''SPI-NAND subsystem''' (内核空间)
SPI-NAND协议在MTD子系统中用于连接SPI NAND闪存。

* '''SPI-NOR subsystem''' (内核空间)
MTD子系统中使用SPI-NOR协议来连接SPI NOR闪存。

* '''FMC driver''' (内核空间) / '''FMC''' (硬件) 
请参阅[[FMC internal peripheral]].

* '''QUADSPI driver''' (Kernel space) / '''QUADSPI''' (Hardware)
请参阅[[QUADSPI internal peripheral]].

===API description===
有关Linux MTD API的描述，请参阅MTD API文档 <ref>[http://www.linux-mtd.infradead.org/doc/general.html#L_mtd_api MTD API]</ref>.

==Configuration ==
===Kernel configuration===
MTD is activated by default in ST deliveries. Nevertheless, if a specific configuration is needed, this section indicates how MTD can be activated/deactivated in the kernel.

Activate MTD in the kernel configuration with the Linux Menuconfig tool: [[Menuconfig or how to configure kernel]].

==== SLC NAND Flash memory ====
<pre>
[*] Device Drivers --->
    <*> Memory Technology Device (MTD) support --->
        <*> RAW/Parallel NAND Device Support --->
            <*> Support for NAND controller on STM32MP Socs.
</pre>

==== SPI NOR/NAND Flash memory ====
<pre>
[*] Device Drivers --->
    <*> Memory Technology Device (MTD) support --->
        Self-contained MTD device drivers --->
            <*> Support most SPI Flash chips (AT26DF, M25P, W25X, ...)      
        <*> SPI NAND device Support
        <*> SPI-NOR device support
    <*> SPI support --->
        -*- SPI memory extension
        <*> STMicroelectronics STM32 QUAD SPI controller
</pre>

===Device tree configuration===
The DT configuration can be done thanks to [[STM32CubeMX]].

==== NAND Flash memory ====
Please refer to the [[FMC_device_tree_configuration| FMC device tree configuration]].

==== SPI NOR/NAND Flash memory ====
Please refer to the [[QUADSPI_device_tree_configuration| QUADSPI device tree configuration]].

== How to use the framework ==
A file system, which handles read/write/erase operations, can be used over the MTD Framework. Please refer to the [[How to support UBIFS through MTD|UBIFS support through MTD]].

You can also interact with the MTD subsystem using the MTD utilities.
The MTD utilities<ref>[http://www.linux-mtd.infradead.org MTD utils]</ref> are a set of tools that can be used to perform operations on Flash memories through the MTD character interface.

The most common utilities used are:
* mtdinfo
* flash_erase
* flashcp
* nandwrite
* nanddump

  root:~# mtdinfo -a
  Count of MTD devices:           9
  Present MTD devices:            mtd0, mtd1, mtd2, mtd3, mtd4, mtd5, mtd6, mtd7, mtd8
  Sysfs interface supported:      yes<br>
  mtd0
  Name:                           fsbl
  Type:                           nand
  Eraseblock size:                262144 bytes, 256.0 KiB
  Amount of eraseblocks:          8 (2097152 bytes, 2.0 MiB)
  Minimum input/output unit size: 4096 bytes
  Sub-page size:                  4096 bytes
  OOB size:                       224 bytes
  Character device major/minor:   90:0
  Bad blocks are allowed:         true
  Device is writable:             true<br>
  mtd1
  Name:                           ssbl
  Type:                           nand
  Eraseblock size:                262144 bytes, 256.0 KiB
  Amount of eraseblocks:          8 (2097152 bytes, 2.0 MiB)
  Minimum input/output unit size: 4096 bytes
  Sub-page size:                  4096 bytes
  OOB size:                       224 bytes
  Character device major/minor:   90:2
  Bad blocks are allowed:         true
  Device is writable:             true<br>
  mtd2
  Name:                           UBI
  Type:                           nand
  Eraseblock size:                262144 bytes, 256.0 KiB
  Amount of eraseblocks:          4078 (1069023232 bytes, 1019.5 MiB)
  Minimum input/output unit size: 4096 bytes
  Sub-page size:                  4096 bytes
  OOB size:                       224 bytes
  Character device major/minor:   90:4
  Bad blocks are allowed:         true
  Device is writable:             true<br>
  mtd3
  Name:                           fsbl1
  Type:                           nor
  Eraseblock size:                65536 bytes, 64.0 KiB
  Amount of eraseblocks:          4 (262144 bytes, 256.0 KiB)
  Minimum input/output unit size: 1 byte
  Sub-page size:                  1 byte
  Character device major/minor:   90:6
  Bad blocks are allowed:         false
  Device is writable:             true<br>
  mtd4
  Name:                           fsbl2
  Type:                           nor
  Eraseblock size:                65536 bytes, 64.0 KiB
  Amount of eraseblocks:          4 (262144 bytes, 256.0 KiB)
  Minimum input/output unit size: 1 byte
  Sub-page size:                  1 byte
  Character device major/minor:   90:8
  Bad blocks are allowed:         false
  Device is writable:             true<br>
  mtd5
  Name:                           ssbl
  Type:                           nor
  Eraseblock size:                65536 bytes, 64.0 KiB
  Amount of eraseblocks:          32 (2097152 bytes, 2.0 MiB)
  Minimum input/output unit size: 1 byte
  Sub-page size:                  1 byte
  Character device major/minor:   90:10
  Bad blocks are allowed:         false
  Device is writable:             true<br>
  mtd6
  Name:                           logo
  Type:                           nor
  Eraseblock size:                65536 bytes, 64.0 KiB
  Amount of eraseblocks:          4 (262144 bytes, 256.0 KiB)
  Minimum input/output unit size: 1 byte
  Sub-page size:                  1 byte
  Character device major/minor:   90:12
  Bad blocks are allowed:         false
  Device is writable:             true<br>
  mtd7
  Name:                           nor_user
  Type:                           nor
  Eraseblock size:                65536 bytes, 64.0 KiB
  Amount of eraseblocks:          980 (64225280 bytes, 61.2 MiB)
  Minimum input/output unit size: 1 byte
  Sub-page size:                  1 byte
  Character device major/minor:   90:14
  Bad blocks are allowed:         false
  Device is writable:             true<br>
  mtd8
  Name:                           58003000.qspi
  Type:                           nor
  Eraseblock size:                65536 bytes, 64.0 KiB
  Amount of eraseblocks:          1024 (67108864 bytes, 64.0 MiB)
  Minimum input/output unit size: 1 byte
  Sub-page size:                  1 byte
  Character device major/minor:   90:16
  Bad blocks are allowed:         false
  Device is writable:             true

==How to trace and debug the framework==

===How to monitor===

The sysfs interface provides detail information on each mtd device.

  root:~# cat /sys/class/mtd/mtd0/name
  fsbl
  root:~# cat /sys/class/mtd/mtd0/type
  nand
  root:~# cat /sys/class/mtd/mtd0/erasesize
  262144
  root:~# cat /sys/class/mtd/mtd0/ecc_strength
  8
  root:~# cat /sys/class/mtd/mtd0/bad_blocks
  0
  root:~# cat /sys/class/mtd/mtd0/ecc_failures
  0

===How to trace===
A detail dynamic trace is available here [[How to use the kernel dynamic debug]].

  root:~# echo "file drivers/mtd/* +p" > /sys/kernel/debug/dynamic_debug/control

==Source code location==
The MTD framework is {{CodeSource | Linux kernel | drivers/mtd  | here}}.

==To go further==
Please refer to the MTD FAQs documentation <ref>[http://www.linux-mtd.infradead.org/faq/general.html MTD FAQs]</ref>.

==References==
Please refer to the following links for full description:

<references />

<noinclude>
{{ArticleBasedOnModel | Framework overview article model}}
[[Category:Mass storage]]
</noinclude>