MTD overview

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SUMMARY
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

MTD v1.1.0.png

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 [1].

  • 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 [2].

  • 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[3].

  • JFFS2 (内核空间)

日记Flash文件系统。 请参考MTD JFFS2文档 [4].

  • UBI (内核空间)

未分类的块图像。 请参考MTD UBI文档 [5].

  • UBIFS (内核空间)

UBI文件系统。 请参考MTD UBIFS文档[6].

  • 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 [7].

Configuration

Kernel configuration

ST交货中默认激活MTD。 但是,如果需要特定的配置,则本节说明如何在内核中激活/停用MTD。

使用Linux Menuconfig工具在内核配置中激活MTD:Menuconfig or how to configure kernel.

SLC NAND Flash memory

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

SPI NOR/NAND Flash memory

[*] 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

Device tree configuration

借助STM32CubeMX可以完成DT配置。

NAND Flash memory

请参考 FMC device tree configuration.

SPI NOR/NAND Flash memory

请参考 QUADSPI device tree configuration.

How to use the framework

可以在MTD框架上使用处理读/写/擦除操作的文件系统。 请参考UBIFS support through MTD.

您还可以使用MTD实用程序与MTD子系统进行交互。 MTD实用程序[8] 是一组工具,可用于通过MTD字符接口对闪存执行操作。 最常用的实用程序是:

  • 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
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
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
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
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
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
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
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
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
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

sysfs界面提供有关每个mtd设备的详细信息。

 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

详细动态跟踪可在此处 How to use the kernel dynamic debug.

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

Source code location

MTD框架为drivers/mtd | |}} here .

To go further

请参阅MTD常见问题解答文档 [9].