移植Linux内核到norflash.docx

开发板上只有NorFlash，所以为了实现层次文件系统，需要为Linux2.6.20增加NorFlashMTD驱动支持。其实工作量并不大，因为已经有现成的程序可供参考。MTD的驱动程序都集中在drivers/mtd里面。我们需要做的，仅仅是在drivers/mtd/maps下增加自己的分区表。因为有参考的代码，所以比较容易。（1）构建配置选项首先，根据edb7312.c构建自己的mtd分区表驱动（根据cfi_flagadm.c这个文件也可以奥，看情况吧！）。$cddrivers/mtd/maps/$cpedb7312.cat91rm9200.c然后，修改drivers/mtd/maps/Kconfig，增加自己的配置选项。/拷贝过EDB7312稍作修改即可configMTD_AT91RM9200tristateCFIFlashdevicemappedonAT91RM9200dependsonARM&MTD_CFIhelpThisenablesaccesstotheCFIFlashontheATMELAT91RM9200DKboard.Ifyouhavesuchaboard,sayYhere.最后，修改Makefile，增加编译项目。obj-$(CONFIG_MTD_EDB7312)+=edb7312.oobj-$(CONFIG_MTD_AT91RM9200)+=at91rm9200.o这样，自己建立的MTD分区表驱动就可以编译进内核了。（2）修改分区表信息因为第一步的工作中，at91rm9200.c实际上还是edb7312.c的内容，所以需要根据自己的开发板norflash的配置做一下修改。#include#include#include#include#include#include#include#ifdefCONFIG_MTD_PARTITIONS#include#endif#defineWINDOW_ADDR0x10000000/*physicalpropertiesofflash*/#defineWINDOW_SIZE0x00800000/*intel28F640J3A8MB*/#defineBUSWIDTH2/*databuswidth16bits*/*canbecfi_probe,jedec_probe,map_rom,NULL;*/#definePROBETYPEScfi_probe,NULL#defineMSG_PREFIXAT91RM9200-NOR:/*prefixforourprintk()s*/#defineMTDIDat91rm9200-%d/*formtdparts=partitioning*/staticstructmtd_info*mymtd;structmap_infoat91rm9200nor_map=.name=NORflashonAT91RM9200DK,.size=WINDOW_SIZE,.bankwidth=BUSWIDTH,.phys=WINDOW_ADDR,;#ifdefCONFIG_MTD_PARTITIONS/*MTDpartitioningstuff*/staticstructmtd_partitionat91rm9200nor_partitions5=/U-boot128KB.name=U-boot,.size=0x20000,.offset=0,/uImage2MB.name=Kernel,.size=0x200000,.offset=0x20000,/RootFS3MB.name=RootFS,.size=0x300000,.offset=0x220000,/UserFS.name=Jffs2,.size=0x2C0000,.offset=0x520000,/P=Parameters,.size=0x20000,.offset=0x7E0000,;staticconstchar*probes=NULL;#endifstaticintmtd_parts_nb=0;staticstructmtd_partition*mtd_parts=0;int_initinit_at91rm9200nor(void)staticconstchar*rom_probe_types=PROBETYPES;constchar*type;constchar*part_type=0;printk(KERN_NOTICEMSG_PREFIX0x%08xat0x%08xn,WINDOW_SIZE,WINDOW_ADDR);at91rm9200nor_map.virt=ioremap(WINDOW_ADDR,WINDOW_SIZE);if(!at91rm9200nor_map.virt)printk(MSG_PREFIXfailedtoioremapn);return-EIO;simple_map_init(&at91rm9200nor_map);mymtd=0;type=rom_probe_types;for(;!mymtd&*type;type+)mymtd=do_map_probe(*type,&at91rm9200nor_map);if(mymtd)mymtd-owner=THIS_MODULE;#ifdefCONFIG_MTD_PARTITIONSmtd_parts_nb=parse_mtd_partitions(mymtd,probes,&mtd_parts,0);if(mtd_parts_nb0)part_type=detected;if(mtd_parts_nb=0)mtd_parts=at91rm9200nor_partitions;mtd_parts_nb=ARRAY_SIZE(at91rm9200nor_partitions);part_type=static;#endifadd_mtd_device(mymtd);if(mtd_parts_nb=0)printk(KERN_NOTICEMSG_PREFIXnopartitioninfoavailablen);elseprintk(KERN_NOTICEMSG_PREFIXusing%spartitiondefinitionn,part_type);/mymtd为mastermtd_info它不被添加到数组mtd_table中，它只用于初始化/每一个分区的mtd_info。而后将每一个分区对应的mtd_info添加到数组mtd_table/供上层调用。MTD原始设备驱动层的主要工作就是向mtd_table中添加mtd_info。add_mtd_partitions(mymtd,mtd_parts,mtd_parts_nb);return0;iounmap(void*)at91rm9200nor_map.virt);return-ENXIO;staticvoid_exitcleanup_at91rm9200nor(void)if(mymtd)del_mtd_device(mymtd);map_destroy(mymtd);if(at91rm9200nor_map.virt)iounmap(void*)at91rm9200nor_map.virt);at91rm9200nor_map.virt=0;module_init(init_at91rm9200nor);module_exit(cleanup_at91rm9200nor);MODULE_LICENSE(GPL);MODULE_AUTHOR(MariusGroeger);MODULE_DESCRIPTION(GenericconfigurableMTDmapdriver);（3）配置内核增加MTD，和相应的文件系统的支持。DevicesDrivers-MemoryTechnologyDevices(MTD)-MemoryTechnologyDevice(MTD)supportMTDpartitioningsupportDirectchardeviceaccesstoMTDdevicesCachingblockdeviceaccesstoMTDdevicesRAM/ROM/Flashchipdrivers-DetectflashchipsbyCommonFlashInterface(CFI)probeSupportforIntel/SharpflashchipsMappingdriversforchipaccess-CFIFlashdevicemappedonAT91RM9200FileSystems-Miscellaneousfilesystems- Journalling Flash File System v2 (JFFS2) support Compressed ROM file system support (cramfs)这里选择cramfs或者Jffs2的支持。（4）编译，然后加载makeImage编译，然后制作成uImage。这是JFFS2作为根文件系统的信息：TOPDIR=$($(whichpwd)TMP=$TOPDIR/linux.binTARGET=$TOPDIR/uImagearm-linux-objcopy-Obinary-Svmlinux$TMP&gzip-v9$TMP&mkimage-nRAMdisk-Aarm-Olinux-Tkernel-Cgzip-a0x20008000-e0x20008000-d$TMP.gz$TARGET&cp$TARGET/mnt/hgfs/common&rm-f$TMP*可以看到MTD分区信息。进入shell界面，然后查看/proc/mtd，如下：AT91RM9200-NOR:0x00800000at0x10000000NORflashonAT91RM9200DK:Found1x16devicesat0x0in16-bitbankIntel/SharpExtendedQueryTableat0x0031Usingbufferwritemethodcfi_cmdset_0001:ErasesuspendonwriteenabledAT91RM9200-NOR:usingstaticpartitiondefinitionCreating5MTDpartitionsonNORflashonAT91RM9200DK:0x00000000-0x00020000:U-boot0x00020000-0x00220000:Kernel0x00220000-0x00520000:RootFS0x00520000-0x007e0000:Jffs20x007e0000-0x00800000:Parameters可以看到加载是正确的。内核：linux-nor flash芯片：SST39VF6401B网上有文章说了如何让linux内核支持nor flash。不过那些转载的文章中没有头文件(因为使用了，在一些网页中是不会显示的，详细请参考HTML相关资料)。后来研究了类似的驱动文件，发现它们都是大同小异，只是在一些参数上有改变而已。本文中源代码基于那些转载文章的代码。MTD设备驱动程序在./driver/mtd下面，分为nor flash和nand flash两种。在chips中定义了几种访问nor的接口，包括cfi、jedec、map_ram和map_rom，而实际芯片所要添加的“驱动程序”放到maps目录下(比如本文使用的s3c2440-flash.c文件，详见文章后面)。从map这个单词来看，它描述的是一些映射信息，当然也包括了芯片信息，如总大小、块总数、访问接口等等。这个过程其实是在内核代码树中添加自己的驱动的过程，当然是一些“标准”步骤了：在对应的代码树目录下，添加驱动源代码文件、在Makefile添加内容、在Kconfig添加内容，当然，还需要在make menuconfig里配置。1、./driver/mtd/maps/Makefile在这个Makefile最后添加：obj-$(CONFIG_MTD_S3C2440)+=s3c2440-flash.o这个CONFIG_MTD_S3C2440由内核配置所得。2、./driver/mtd/maps/Kconfig在这个Kconfig文件最后添加(但在endmenu之前)：configMTD_S3C2440tristate“CFI Flash device mapped on S3C2440dependsonARM&MTD_CFIhelpThisenablesaccesstotheCFIFlashontheSMDK2440board.Ifyouhavesuchaboard,sayYhere.这里的MTD_S3C2440就是前面Makefile中的那个，注意，CONFIG_前缀是内核自己添加的。可以在编译内核后生成的autoconf.h文件中查看该宏定义。3、内核配置在Device Drivers Memory Technology Device (MTD) support 下面：MappingdriversforchipaccessCFIFlashdevicemappedonS3C2440RAM/ROM/Flash chip drivers DetectflashchipsbyCommonFlashInterface(CFI)probe*Flashchipdriveradvancedconfigurationoptions*SpecificCFIFlashgeometryselection*Support16-bitbuswidth*Support1-chipflashinterleave4、./driver/mtd/maps/s3c2440-flash.c代码见文章后面。这个文件主要是修改前面的几个宏定义。我特地添加一些调试语句。开始时我使用内核，驱动中使用cfi_probe接口，但是没有显示分区信息，后来我添加多几个接口才发现它是使用map_rom。这个过程花费了一些时间。在内核中，启动信息如下：S3C2440-NOR:0x00800000at0x01000000S3C2440-NOR:func:init_s3c2440nor120mymtd:0type:cfi_probeS3C2440-NOR:func:init_s3c2440nor120mymtd:0type:jedec_probeS3C2440-NOR:func:init_s3c2440nor120mymtd:c39cb600type:map_romS3C2440-NOR:usingstaticpartitiondefinitionCreating4MTDpartitionson“NOR Flash(SST39VF6401B) on S3C2440:0x000000000000-0x000000030000:“U-Boot”0x000000030000-0x000000240000:“Kernel”0x000000240000-0x0000007f0000:“RootFS(jffs2)”0x0000007f0000-0x000000800000:“Parameter”可以看到，的确是使用map_rom接口。但是，当我使用时，发现它使用的是cfi_probe接口，启动信息如下：S3C2440-NOR:0x00800000at0x01000000NORFlash(SST39VF6401B)onS3C2440:Found1x16devicesat0x0in16-bitbank.ManufacturerID0x0000bfChipID0x00236dnumberofCFIchips:1#LLdebugS3C2440-NOR:func:init_s3c2440nor121mymtd:c3a19200type:cfi_probemtd:Givingoutdevice0toNORFlash(SST39VF6401B)onS3C2440S3C2440-NOR:usingstaticpartitiondefinitionCreating4MTDpartitionson“NOR Flash(SST39VF6401B) on S3C2440:0x000000000000-0x000000030000:“U-Boot”mtd:Givingoutdevice1toU-Boot0x000000030000-0x000000240000:“Kernel”mtd:Givingoutdevice2toKernel0x000000240000-0x0000007f0000:“Rootfs(jffs2)”mtd:Givingoutdevice3toRootfs(jffs2)0x0000007f0000-0x000000800000:“Parameter”mtd:Givingoutdevice4toParameter与前面不同的是，它打印了芯片的信息，如厂商ID、芯片ID等等。这是我想不通的地方，也是我采用新内核的原因。不过，在这片nor flash上使用jffs2文件系统却不成功，出现了大量的警告信息，提示说制作根文件系统时的erase block有问题。s3c2440-flash.c源代码：/* $Id:s3c2410.c,v1.002006/12/0510:18:14gleixnerExp$* HandlemappingoftheNORflashonCogentS3C2410boards* Copyright2002SYSGOReal-TimeSolutionsGmbH* Thisprogramisfreesoftware;youcanredistributeitand/ormodify* itunderthetermsoftheGNUGeneralPublicLicenseversion2as* publishedbytheFreeSoftwareFoundation.*/* LateLee* Thisfileismodifiedandthefilenamehaschangedtos3c2440-flash.c.* TheSMDK2440boardhasonlyoneflashbankwhichisa64Mbit(4Mx16)SSTSST39VF6401B;* 128x64KiBblocks.* ThiscodeisGPLed.*/#include#include#include#include#include#include#include#include#ifdefCONFIG_MTD_PARTITIONS#include#endif#defineWINDOW_ADDR0x01000000/*physicalpropertiesofflash*/#defineWINDOW_SIZE0x800000/*8MB*/#defineBUSWIDTH2/*2*8=16*/#defineFLASH_BLOCKSIZE_MAIN0x10000/*64KB(0x10000)128blocks*/#defineFLASH_NUMBLOCKS_MAIN128/*canbe“cfi_probe”,“jedec_probe”,“map_rom”,NULL;*/#definePROBETYPES“cfi_probe”,“jedec_probe”,“map_rom”,NULL#defineMSG_PREFIX“S3C2440-NOR:”/*prefixforourprintk()s*/#defineMTDID“s3c2440-nor”/*formtdparts=partitioning*/#defineDEBUG_FLASH#ifdefDEBUG_FLASH#defineflash_debug(fmt,args)printk(KERN_NOTICE“# LL debug “MSG_PREFIXfmt,#args)#else#defineflash_debug(fmt,args)#endifstaticstructmtd_info*mymtd;structmap_infos3c2440nor_map=.name=“NOR Flash(SST39VF6401B) on S3C2440,.size=WINDOW_SIZE,.bankwidth=BUSWIDTH,.phys=WINDOW_ADDR,;#ifdefCONFIG_MTD_PARTITIONS/* MTDpartitioningstuff*/staticstructmtd_partitionstatic_partitions=/*0:U-Boot:0-0x300000x30000=192KB*/.name=“U-Boot”,.size=0x030000,.offset=0x0,/*1:Kernel:0x30000-0x2400000x210000=2112KB=2.0625MB*/.name=“Kernel”,.size=0x210000,.offset=0x30000,/*2:Rootfs(jffs2):0x240000-0x7f00000x5b0000=5824KB=5.6875MB*/.name=“Rootfs(jffs2)”,.size=0x5b0000,.offset=0x240000,/*3:U-BootParameters:0x7f0000-0x8000000x10000=64KB*/.name=“Parameter”,.size=0x010000,.offset=0x7f0000,;/static const char *probes = “RedBoot”, “cmdlinepart”, NULL ;staticconstchar*probes=NULL;#endifstaticintmtd_parts_nb=0;staticstructmtd_partition*mtd_parts=0;int_initinit_s3c2440nor(void)staticconstchar*rom_probe_types=PROBETYPES;constchar*type;constchar*part_type=0;printk(KERN_NOTICEMSG_PREFIX“0x%08x at 0x%08xn”,WINDOW_SIZE,WINDOW_ADDR);s3c2440nor_map.virt=ioremap(WINDOW_ADDR,WINDOW_SIZE);if(!s3c2440nor_map.virt)printk(MSG_PREFIX“failed to ioremapn”);return-EIO;simple_map_init(&s3c2440nor_map)