Freescale MQX™ FFS User Guide
Contents
1. Section 1 Newer MRU section 4 Section 2 The 1 used section Most Recently Used MRU section in Section 3 SDRAM nee Other section in 3 update to new MRU section SDRAM Cache miss gt 1 evict Section N 1 ni H Eaa The 2 used section 2 fetch N LRU sectionin SDRAM Section N RAM Zone Map in Flash memory Figure 6 12 Cache Array for Zone Map 6 5 3 Non sequential Sector Map The Non sequential sector map NSSM is responsible for tracking the block s logical sectors within the physical location of a block It also manages the mechanism which updates the block contents in an efficient manner All upper layer sectors reading and writing must utilize a non sequential sector map to either find the physical location of a logical sector or to get the page where a new sector should be written The NSSM is composed of two key components First it has a map which explains the relationship of the logical sector to a physical page within a block This allows logical sectors to be written to the block in any order which is important for ensuring that pages are only written sequentially within the block as required by NAND The map also enables logical sectors to be written to the block more than once with the most recent copy taking precedence The second element is a backup block The backup block contains previous contents of the block and allows only new sectors to be2. NAND WL IF NSSM Manager Mapper Zone Map Phy Map us l l Initialize M nitialize successfully X Initialize failed T 1 ae 1 Initialize gt _ Load or scan and build from NAND Flash memory device Load Build successfully D 4 Load Build failed Load or scan and build from NAND Flash memory device 1 1 4 Load Build successfully 1 1 i X Load Build failed Xi Initialize failed T T T Figure 6 1 WL Initialization Sequence Diagram In this sequence diagram e NAND WL IP is an interface for WL module It is responsible for initializing all maps and for interacting with upper layers NSSM Manager manages all Non sequential Sector maps in the Red Black tree structure and LRU list e Mapper manages Zone Map and Phy Map Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 1 MQX Wear Leveling Internal Software Flow 6 2 Read Sector Flow Virtual Block Number Zone Map Phy Map Relative Physical Block Number Logical Sector Mathematical Physical Sector Number Converter Number Virtual Block Number eel Relative Physical Virtual Sector Offset 2 Sector Offset block Figure 6 2 WL Read Sect
3. MQX_FILE_PTR fd_ptr IN the remaining portion of the name of the device char_ptr open_name_ptr IN the flags to be used during operation char_ptr flags Freescale MQX Flash File System User Guide Rev 1 4 5 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 2 4 _io_nandflash_wl_close Description This function is used to close nand flash driver Prototype _mqx_int _io_nandflash_wl_close IN the file handle for the device being closed MQX_FILE_PTR fd_ptr Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 2 5 _io_nandflash_wl_read Description Modules of upper layers use this function to read a logical sector from nand flash memory device via core and NFC Physical media Prototype _mqx_int _io_nandflash_wl_read IN the file handle for the device MQX_FILE_PTR fd_ptr IN where the data is to be stored char_ptr data_ptr IN the number of pages to input _mqx_int num Freescale MQX Flash File System User Guide Rev 1 4 7 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 2 6 _o_nandflash_wl write Description Modules of the upper layers use this function to write a logical sector from nand flash memory device via core and NFC Physical media Prototype _mqx_int _io_nand
4. exit format lt drive gt lt volume label gt help lt command gt mkdir lt directory gt pwd read lt filename gt lt bytes gt lt seek_mode gt lt offset gt 1 ren lt oldname gt lt newname gt rmdir lt directory gt sh lt filename gt type lt filename gt write lt filename gt lt bytes gt lt seek_mode gt lt offset gt fsopen fsclose nanderase nandrepair nanderasechip hell gt N Figure 4 2 MFS example user interface New Shell Commands This example is based on existing MFS SD Card example Therefore it has common shell commands and some new commands which are only used for FFS New shell commands are These commands are shown in the diagram below fsopen fsclose nanderase nandrepair nanderasechip Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 25 Using MQX NAND Flash Wear Leveling Module WL Open Yes gt Repair Erase No Try again y e ORRON MFS Open D ERROR Not DOS DISK No Ready to USE Yes Format ERROR No Success 4 6 2 1 fsopen Command This command is used to open NAND flash memory with wear leveling Each sub module Media DataDrive Mapper is initialized in order Freescale MQX Flash File System User Guide Rev 1 4 26 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Mod
5. Unused Physical Sector N Unused Backup Block Primary Block NEW Primary Block Mappedto gt Lee Mapped to y Mapped to v Request new block The same logical from PhyMap block VBA Figure 6 17 MergeBlocksCore for Non sequential Sector NOTE Occasionally because of power loss the backup block and the primary block are not merged together In this situation two physical blocks are assigned to only one logical block When the conflict occurs WL needs to re merge the blocks Freescale MQX Flash File System User Guide Rev 1 4 16 Freescale Semiconductor MQX Wear Leveling Internal Software Flow Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 17 MQX Wear Leveling Internal Software Flow Freescale MQX Flash File System User Guide Rev 1 4 18 Freescale Semiconductor Revision History To provide the most up to date information the revision of our documents on the World Wide Web will be the most current Your printed copy may be an earlier revision To verify you have the latest information available see freescale com mqx The following revision history table summarizes changes contained in this document cla den Description of Changes Rev 1 0 04 2012 Initial Release coming with MQX 3 8 0 Rev 1 1 07 2012 Update document for MQX 3 8 1 Rev 1 2 12 2012 Update document for MQX 4 0 0 o e A Rev 1 4 12 2013 Updates speci
6. l l l l ector Number i i l l l l NAND WLIF Zone Map Phy Map Non sequential Sector Map l l Get relative Physical Block Number re of Virtual Block Number gt of Logical Sector Number ___ Assign a new free physical block if does not find out Xle Return OxFF buffer when can t get relative Physical Block Return a new free Physical Block Number Return the relative i e Physical Block Number Get the next available Physical Sector Offset of Virtual Sector Number of Logical Sector Number within the relative Physical Block Number gt Al ooo ooooooooooooo There is something wrong E Li 4 Return suitable Physical Sector Offset Update Non sequential Sector Map p Figure 6 5 WL Write Sector Sequence Diagram In this sequence diagram Step 1 If the MES wants to write data to a logical sector it transfers a logical sector address to the NAND WL IF of the NAND driver WL needs to make sure that a given logical sector is not out of bounds Step 2 The NAND WL IF converts the input logical sector number mathematically into a virtual block number and a virtual block offset Step 3 If the Zone map object is loaded or built from the initialization phase the NAND WL IF searches the map to figure out the relative physical block of this virtual block Ifthe physic
7. 4 2 9 _io_nandflash_wl_internal_read_with_metadata Description This function is used to read all data in a sector It s called from _io_nandflash_wl_ioctl function by the input command Prototype _mqx_int _io_nandflash_wl_internal_read_with_metadata IN the file handle for the device MQX_FILE_PTR fd_ptr IN where the data is to be stored char_ptr page_struct_ptr IN the number of pages to input _mqx_int num OUT the error is returned uint_32_ptr ret_err Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 2 10 io nandflash_wl_ internal write with_metadata Description This function is used to write data to a sector and metadata in the spare area Prototype _mqx_int _io_nandflash_wl_internal_write_with_metadata IN the file handle for the device MQX_FILE_PTR fd_ptr IN where the data is stored char_ptr page_buff_struct IN the number of pages to output _mqx_int num OUT the error is returned uint_32_ptr ret_err Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 12 Using MQX NAND Flash Wear Leveling Module 4 3 NFC Physical Media Class e NEC Physical Media class which is a subclass of the NandPhysicalMedia abstract class is a hardware dependent code that is responsible for bridging betw
8. Guide Rev 1 4 28 Freescale Semiconductor MQX Wear Leveling Internal Functionality Chapter 5 MQX Wear Leveling Internal Functionality This section describes the functionalities of Wear Leveling module in NAND flash driver 5 1 Role of WL Module in NAND Driver This module is mainly responsible for mapping from a virtual page address to a physical page address By doing so the wear leveling works transparently with the upper layer such as MQX MES Applications in the upper layer pass a logical sector or virtual page address to WL s module resists inside NAND driver After that the WL mechanism searches its internal mapping table on RAM or flash memory to find the desired physical page address There are a few existing mapping tables namely PhyMap ZoneMap and NonSequentialSectorMap maintained in the WL module In the initialization step WL tries to build up the PhyMap and ZoneMap by scanning all blocks in the reserved area on NAND physical to find the suitable map structure NonSequentialSectorMap is built from metadata in every physical page If NAND memory is fresh or does not contain WL information these maps will initialize with default parameters On each read write operation from the upper layer these maps will update by getting rid of a non existing entry and fetching a new one from the flash memory Finally when upper layer closes the flash driver all map data will be flushed to the physical pages encapsulated in a sp
9. NAND Flash WL module code before this module can initialize and start read write on NAND physical device The pre defined layout is discussed in detail in section 4 1 Configure pre defined data drive layout e After MQX NAND Flash WL is initialized successfully upper layer can issue read write operation by using standard FIO function such as read write seek and others Section 4 6 MFS example user manual demonstrates how to cooperate MFS with MQX NAND Flash WL module which allows FAT file system to access on top of NAND Flash Wear Leveling module e Section 4 3 NFC Physical media discusses a functionality of the NFC Physical Media class which is a hardware dependent code in WL module 4 1 Configure Pre defined Data Drive Layout One data drive is defined by default in the file given below lt mqx gt source io nandflash_wl nandflash_wl h gt Developer can use two macros as shown below to configure the start location and size for the first data drive define NANDFLASH_1ST_DATA_DRIVE_SIZE_IN_BLOCK define NANDFLASH_1ST_DATA_DRIVE_START_BLOCK For example define NANDFLASH_1ST_DATA_DRIVE_SIZE_IN_BLOCK 90 define NANDFLASH_1ST_DATA_DRIVE_START_BLOCK 110 In this example the data drive size in blocks is 90 This data driver is expanded from 110th to 199th block If a developer wants to define data drivers manually that is some data drivers are not placed continuous
10. System User Guide Rev 1 4 Freescale Semiconductor MQX Wear Leveling Internal Software Flow free physical block that is available in Phy map is assigned and a buffer filled with OxFF sent back to MES e Step 4 The NAND WL IF scans all entries in Non sequential Sector Map of the virtual block to get location offset of the virtual sector in the block which it belongs to If the Non sequential Sector Map was not loaded to SDRAM each sector of the relative physical sector is scanned to read metadata and Non sequential Sector Map is built e Step 5 If WL has the physical sector number and the physical sector offset number it knows exactly which physical sector must be sent to the NFC However WL also needs to confirm whether the sector is written or not If it is not written it returns an OxFF buffer 6 3 Write Sector Flow Mathematical Converter Logical Sector Number Virtual Block Number Zone Map Phy Map Relative Physical Block Number Virtual Block Number Virtual Sector Offset Non sequential Sector Map of the virtual block Figure 6 4 WL Write Sector Flow The next available Physical Sector Offset Freescale MQX Flash File System User Guide Rev 1 4 Available Physical Sector Number Freescale Semiconductor MQX Wear Leveling Internal Software Flow Logical Sector Number Physical l T l
11. This memory management module is located as shown below lt mgx gt source io nandflash_wl wearleveling rtos mqx mem_management cpp 4 4 1 mm_alloc Description This function allocates a buffer with a given size Each buffer includes two signatures at head and tail to trace their status To manage memory it s better to implement this function in place of using standard functions Prototype pointer mm_alloc IN size of requested buffer _mem_size request_size IN file name which requests buffer const char file_name IN Location in file_name int file_loc IN Should zero buffer after allocated boolean isZero IN Is this buffer requested from new operator boolean is_from_operator Freescale MQX Flash File System User Guide Rev 1 4 22 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 4 2 mm_free Description This function is used to free allocated memory It will check the signature included and alert invalid allocated buffer Prototype _mqx_uint mm_ free IN pointer to head of allocated buffer pointer buf Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 23 AN Using MQX NAND Flash Wear Leveling Module 4 5 WL Debug WL Debug is designed to support developers to debug each sub module or all sub modules of the NAND Flash WL core If a d
12. block No for erase request uint32_t startBlockNumber IN Number of block for erase request uint32_t requestedBlockCount OUT Actual erased block uint32_t actualBlockCount Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 18 Using MQX NAND Flash Wear Leveling Module 4 3 7 NFCNandMedia copyPages Description This function is used to copy data of multiple physical sectors data and metadata from a source device to a target device Prototype RtStatus_t NFCNandMedia copyPages IN Target Nand is request for copy to NandPhysicalMedia targetNand IN Start from sector No uint32_t wSourceStartSectorNum IN Copy to target s sector No uint32_t wTargetStartSectorNum IN Number of sector for copying uint32_t wNumSectors IN The temporary sector buffer SECTOR_BUFFER sectorBuffer IN The temporary auxilary buffer SECTOR_BUFFER auxBuffer IN For copy filtering purpose NandCopyPagesFilter filter OUT Actual number of copied pages uint32_t successfulPages Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 3 8 NFCNandMedia isBlockBad Description This function checks whether a given block is bad Prototype bool NFCNandMedia isBlockBad IN Give
13. Freescale MQX Flash File System User Guide MQXFFSUG Rev 1 4 02 2014 4 NA 2 freescale How to Reach Us Home Page freescale com Web Support freescale com support Document Number MQXFFSUG Rev 1 4 02 2014 Information in this document is provided solely to enable system and software implementers to use Freescale products There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits based on the information in this document Freescale reserves the right to make changes without further notice to any products herein Freescale makes no warranty representation or guarantee regarding the suitability of its products for any particular purpose nor does Freescale assume any liability arising out of the application or use of any product or circuit and specifically disclaims any and all liability including without limitation consequential or incidental damages Typical parameters that may be provided in Freescale data sheets and or specifications can and do vary in different applications and actual performance may vary over time All operating parameters including typicals must be validated for each customer application by customer s technical experts Freescale does not convey any license under its patent rights nor the rights of others Freescale sells products pursuant to standard terms and conditions of sale which can be found at the following addre
14. _t uSectorNumber OUT Return read data buffer SECTOR_BUFFER pBuffer OUT Return read auxiliary metadata buffer SECTOR_BUFFER pAuxiliary Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 3 4 NFCNandMedia writePage Description This function reads data and its metadata on given physical sector number from a physical sector in the nand flash memory device Prototype RtStatus_t NFCNandMedia readPage IN Sector number for reading uint32_t uSectorNumber OUT Return read data buffer SECTOR_BUFFER pBuffer OUT Return read auxiliary metadata buffer SECTOR_BUFFER pAuxiliary Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 16 Using MQX NAND Flash Wear Leveling Module 4 3 5 NFCNandMedia eraseBlock Description This function is used to erase a given physical block number Prototype RtStatus_t NFCNandMedia eraseBlock IN Given block for erase request uint32_t uBlockNumber Freescale MQX Flash File System User Guide Rev 1 4 17 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 3 6 NFCNandMedia eraseMultipleBlocks Description This function is used to erase a range of physical blocks Prototype RtStatus_t NFCNandMedia eraseMultipleBlocks IN Start
15. age with metadata add new function for read write page s data and metadata Metadata Spare Read Write operation add new functions for handling spare data which is used on Wear Leveling module These functions simply read write metadata of each pages from spare area In this new architecture organization of virtual pages in physical pages is different with the old architecture g0 g2r0c aL10c Spare data Physical Page 1 Size 64B h la NFC divide by setting Ea NFC_CFG PAGECNT 4 oO ow Y Y y Spare Spare Spare Spare Virtual Page 4 Virtual Virtual Page 3 Virtual Virtual Page 2 Virtual Virtual Page 1 Virtual page 4 page 3 page 2 page 1 Factory Bad Marking at 2048 Physical Page size Figure 3 4 New Organization of Each Virtual Page in Physical Pages By comparing Figure 3 2 and Figure 3 4 all virtual pages are placed in the reserved order By doing so we can preserve the location of Factory Bad Marking byte of NAND flash Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 5 Architecture Overview Freescale MQX Flash File System User Guide Rev 1 4 6 Freescale Semiconductor Chapter 4 Using MQX NAND Flash Wear Leveling Module This chapter explains how a developer can initialize and work with MQX NAND Flash WL module e A pre defined data driver layout must be declared in MQX
16. al block cannot be found that means that no physical block is assigned to this virtual block and that a free physical block which is available in Phy map is assigned Step 4 The NAND WL IF scans all entries in the Non sequential Sector Map of the virtual block to get location offset of the next available virtual sector in the block to which it belongs If the Non sequential Sector Map was not loaded to SDRAM each sector of the relative physical sector 1s scanned to read metadata and Non sequential Sector Map is built later If the next available virtual sector is out of bounds because the physical block is full WL marks that physical block as a backup block and gets a new free block to write data Old backup block needs to be erased and marked as free Step 5 If WL has the physical sector number and the physical sector offset number WL knows exactly which physical sector must be sent to the NFC However if an error occurs when writing and the NFC cannot fix that error WL has to copy content of the physical block to another free block and mark the previous block as bad The NFC continues writing on the new block Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor MQX Wear Leveling Internal Software Flow e Step 6 After the NFC writes successfully the Non sequential Sector Map of the physical block needs to be updated 6 4 Shutdown Flow NAND WLIF NSSM Manager Mapper Zone Map Phy Map I I hit
17. alize initialize success tll hitalee tiled I hitalize Diese us cui ua Info falda anes mme mens ae A A A A CI ee e ee ps A A A pe ora ap e ie Figure 6 6 WL Shutdown Flush Sequence Diagram Before releasing all variable that is allocated on memory WL needs to flush all Non sequential Sector Maps by merging the backup block and the primary block to free the unused block and write Zone map and Phy map on NAND flash memory device if they are not saved 6 5 Zone Map Physical Map and Non sequential Sector Map Structure Zone Map and Physical Map are organized inside the flash memory as shown in the figure below Freescale MQX Flash File System User Guide Rev 1 4 5 Freescale Semiconductor MQX Wear Leveling Internal Software Flow All data 8 spare are OxFF indicate this page is FREE FREE y First LBA Page 0 FREE FREE Page 1 FREE FREE Page 2 Section 1 Page 3 Section 2 age 4 Section 3 Page 5 Section 4 A Page or Section organization top section page Idx A Map Block Organization NAND Flash memory Figure 6 7 Zone Map and Phy Map Organization in Flash Memory Maps are located in a Reserved Area Block that the user s data cannot touch Each map occupies one block and the others are backups One map block contains multiple sections that are spread continuously in virtual pages on the flash memory To slow down the pre
18. bution is done by an internal re mapping mechanism between logical physical block address and writing strategy The wear leveling writes all new or updated data to a free block which is picked from a head of the free block FIFO then erases the old data block and eventually puts this erased block to the end of the free block FIFO This process is done in the background and for that reason is completely transparent to the host system Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 1 Introduction 1 4 Outline The outline of this document is as follows e Section 1 Introduces the purpose of this project and the brief overview of NAND flash memory and wear leveling e Section 2 Abbreviations and acronyms and reference are used in this document e Section 3 Architecture overview e Section 4 Using MQX NAND Flash Wear Leveling module e Section 5 Functionalities of Wear Leveling module in this project e Section 6 Internal software flow for Wear Leveling module Freescale MQX Flash File System User Guide Rev 1 4 2 Freescale Semiconductor 2 1 Chapter 2 Abbreviations Acronyms and References Abbreviations Acronyms Table 2 1 Acronyms and Abbreviations Acronym Description API Application Programming Interface BM Bare Metal HW Hardware IF Interface App Application NAND In NAND flash memory users access read write
19. cronyms and Abbreviations Acronym Description M53015_Lon Evaluation Board for ColdFire MCF5301X CPU This board contains 8M x 16 bit NOR flahs memory gjing M54455_Red Evaluation Board for ColdFire MCF5445X CPU This board contains 02 NOR flash memories 16 MB strip 512 KB M54418_Mod Evaluation Board for ColdFire MCF5441X CPU FSOFT uses TWR MCF5441X for testing purpose this elo board also contains 2Gb NAND flash memory 2 2 References Table 2 2 References Serial No Document Name Version 1 MQX RTOS Source Code 4 0 2 2 Freescale MQX 1 0 Drivers User Guide Rev 9 3 MCF5441x Reference Manual Rev 4 4 K70P256M150SF3RM Reference Manual Rev 2 5 K60P144M150SF3RM Reference Manual Rev 2 6 Datasheet for 2Gb NAND Flash 29F2G16AABWP 7 Vybrid Reference Manual Freescale MQX Flash File System User Guide Rev 1 4 2 Freescale Semiconductor Chapter 3 Architecture Overview 3 1 Old NAND Flash Architecture The current Freescale MQX NAND flash architecture contains two key components NAND driver and NAND Flash Controller NFC e NAND driver Generally this driver offers functions such as read write erase raw and IOCTL operations for upper layer e NAND Flash Controller NEC This layer providers the NAND HW abstraction which allows the hardware independent implementation of higher layers that is NAND driver The architecture of NAND flash driv
20. e Map Mapping Table between Logical Block Address and Physical Block Address WL splits this map into many sections and writes to flash memory Each section contains entries whereby each entry stores 16 or 24 bits physical block address Freescale MQX Flash File System User Guide Rev 1 4 9 Freescale Semiconductor MQX Wear Leveling Internal Software Flow These entries are encapsulated with a header and write to NEXT available virtual page in specific ZoneMap block Each Virtual page section will store r MAX_ENTRIES_PER_PAGE entries Section 0 with header A start BA LBA1 tota Entries top section page Idx lt Block stores ZoneMap NAND Flash memory Index of Section contains entry for LBAi LB Ai Total Entries Per Section Figure 6 11 Zone Map Organization In memory and Flash WL maintains this map in flash memory the same way as it does the Phy Map However it is difficult to load the entire Zone Map to memory beacause of the limited RAM As a result only some sections of the zone map are loaded into a cache array for fast look up If the cache array is full WL uses the Least Recently Used LRU strategy to remove and fetch a new one from flash memory Freescale MQX Flash File System User Guide Rev 1 4 10 Freescale Semiconductor MQX Wear Leveling Internal Software Flow Cache Array which stores n Section of Zone map wil be filled until it is full
21. ebug module is enabled all messages of verbose module will be printed out by using WL_LOG statement The syntax is shown below WL_LOG lt WL_Module gt lt Log_type gt lt Message gt Try to load the zone and phy maps from media WL_LOG WL MODULE MAPPER WL LOG INFO Loading maps from media n Hif WL_DEBUG uint_32 g wl log module attributes WL_MODULE GENERAL WL_MODULE_HAL lt Disabled debug module WL_ MODULE MAPPER WL MODULE MEDIA WL_ MODULE LOGICALDRIVE WL MODULE DEFEERREDTASK 4 Enabled debug modules WL MODULE MEDIABUFFER WL MODULE NANDWL WL_ MODULE NANDWL TESTING This module is located as shown below lt mqx gt source io nandflash_wl wearleveling wl_common cpp Freescale MQX Flash File System User Guide Rev 1 4 24 Freescale Semiconductor 4 6 4 6 1 MFS Example User Manual User Interface Using MQX NAND Flash Wear Leveling Module coM1 57600baud Tera Term YT _ 0 x 4 6 2 File Edit Setup Control Window Help NAND Flash demo If this is the first time you use the demo you should run nanderasechip first hell build Jan 9 2812 open ight lt c gt 2688 Freescale Semiconductor hell gt help vailable commands cd lt directory gt copy lt source gt lt dest gt create lt filename gt lt mode gt del lt file gt disect lt sector gt lt device gt dir lt filespec gt 1 lt attr gt di lt sector gt lt device gt
22. ecial structure In addition WL map retains all good blocks and bad blocks on NAND flash memory If WL catches an error related to the writing or erasing operation on a specific block it marks the block as bad and avoids it in the future allocation 5 2 Input and Output of WL Module The following figure depicts WL input and output parameters that are passed between each module and function Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 1 MQX Wear Leveling Internal Functionality ce Read Write on specific Logical Sector Address used on file system Call NAND Read Write raw on ae Physical Page Address Get Metadata from page s Spare area a Figure 5 1 Input Ouput Parameters of WL Module 5 3 Internal Mechanism inside WL Module The most important task for WL module is to get essential information from maps or flash memory and calculate the physical page address from Logical Sector Page Address to Physical Page Address To do so WL must cooperate with maps as shown in the figure below Freescale MQX Flash File System User Guide Rev 1 4 2 Freescale Semiconductor In this figure MQX Wear Leveling Internal Functionality return FREE block gt NAND Read MFS Upper layer A e Read Write raw A logical sector address used on file system Get metadata a NFC WL Module Not found o
23. een WL module and specific hardware NAND Flash Controller NFC This class prototype is discussed in detail in subsequent section NOTE WL can support a new NAND Flash Controller that is CPU does not have NFC hardware by simply creating a new class which is based on NandPhysicalMedia and initializing it properly in NandHal class NFC physical media is located as shown below lt mqx gt source io nandflash_wl wearleveling hal ddi_nand_hal_nfcphymedia cpp 4 3 1 NFCNandMedia NFCNandMedia Description This is a constructor of the NFC Physical media module Prototype NFCNandMedia NFCNandMedia IN chip number for enabling uint32_t chipNumber Freescale MQX Flash File System User Guide Rev 1 4 13 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 3 2 NFCNandMedia initChipParam Description This function initializes all chip parameters such as pages per block page size etc Prototype void NFCNandMedia initChipParam Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 14 Using MQX NAND Flash Wear Leveling Module 4 3 3 NFCNandMedia readPage Description This function reads data and its metadata on a given physical sector number from a physical sector in nand flash memory device Prototype RtStatus_t NFCNandMedia readPage IN Sector number for reading uint32
24. er in MQX can be seen in the figure below Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 1 Architecture Overview App with Filesystem access capability Old NAND Apps MFS MQX File System Partition Manager Device Driver fopen nandflash NAND Read Write RAW Function Read Write Erase IOCTL operation NAND Flash Controller Hardware NAND Physical Figure 3 1 Old NAND Architecture All NAND applications could be interactive with NAND flash driver through I O driver with signature nandflash The smallest unit that NAND apps can read write is Virtual Page Address VPA The VPA points to exactly one physical address on NAND memory However a size of each page in NAND Apps NAND driver is not the same as a page in NAND physical memory The difference is a result of a divider in the NFC hardware For example Freescale MQX Flash File System User Guide Rev 1 4 2 Freescale Semiconductor Architecture Overview TWR MCF54418 board uses MT29F2G16AABWP as NAND physical memory The organization of NAND in this instance is as follows e Device size 2Gb 256MB e Page size 2112 bytes 2048 bytes for user s data 64 bytes for spare data e Block size 64 pages 135 168 bytes 132KB By setting up the NFC HW register the user can logically split the physical page size to a smaller one This configurat
25. fic to MQX 4 1 0 beta release Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor
26. flash_wl_write IN the file handle for the device MQX_FILE_PTR fd_ptr IN where the data is stored char_ptr data_ptr IN the number of pages to output _mqx_int num Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 2 7 _io_nandflash_wil_ioctl Description This function contains a useful control command to communicate with low layer hardware Prototype _mqx_int _io_nandflash_wl_ioctl IN the file handle for the device MQX_FILE_PTR fd_ptr IN the ioctl command _mqx_uint cmd IN OUT the ioctl parameters pointer param_ptr Freescale MQX Flash File System User Guide Rev 1 4 9 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 2 8 _io_nandflash_wl_internal_ read_metadata Description This function is responsible to read only data of the spare area It s called from _io_nandflash_wl_ioctl function by the input command Prototype _mqx_int _io_nandflash_wl_internal_read_metadata IN the file handle for the device MQX_FILE_PTR fd_ptr IN where the data is to be stored char_ptr data_ptr OUT the error is returned uint_32_ptr ret_err Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 10 Using MQX NAND Flash Wear Leveling Module
27. ion can be done by modifying NFC_CFG PAGECNT register For example if we set NFC_CFG PAGECNT to 4 a physical page size will be divided into 4 virtual pages with size 2112B 4 528B in each By doing so user applications can handle smaller page size easily g0 a poc g 1 103 Spare data Physical Page 1 Size 64B NFO divide by setting NFC_CFG PAGECNT 4 aroz a 9L azpoz Spare Spare Spare Spare Virtual Page 2 Virtual Page 3 Virtual Page 4 Virtual Virtual Virtual Virtual Virtual Page 1 page 1 page 2 page 3 page 4 49 1G Figure 3 2 Difference between NAND Physical Organization and Virtual Organization NAND driver currently does not support MQX MES because of the follwing e Getting Block Size in IO_IOCTL_GET_BLOCK_SIZE command NAND driver does not return a correct block size in bytes MQX MES needs a block size in bytes which can be used for read write operations e Identifying a total sector of storage devices through an IOCTL command IO_IOCTL_GET_NUM_SECTORS Currently NAND driver does not implement this IOCTL command 3 2 New Architecture with Wear Leveling WL Capability This solution focuses on a few modifications about MQX NAND flash driver and NAND Flash Controller It helps MFS MQX File System to run on top of NAND flash memory device and makes NAND flash memory device not wear out too quickly This solution also allows the new a
28. lash Wl cC lOS ii da ia il 4 6 10 nadas e o e do sita 4 7 o mandilash W Will NE net nn sia dle oies 4 8 10 nand flash wll 10061 ici i cico iai nie BAe isa 0073 A dal du 4 9 _io_nandflash_wl_internal_read_metadata m eee nenea ee eee nenea 4 10 _io_nandflash_wl_internal_read_with metadata c eee eee eee eee nenea eee 4 11 _io_nandflash_wl_internal_write with_metadata 4 12 NEC Physical Media Class sentent A ia da 4 13 NFCNandMedia NFCNandMedia sis 4 13 NFCNandMedia initChipParam esse acea sta ca aaa ad da noa a aaa aa da aaa d aa 4 14 NPC Nand Media read Page seta a 4 15 NEC Nand Media Wille Pate 5 56 re TR ee SR ce eee 4 16 NFCNandMedia eraseBlock iii 4 17 NFCNandMedia eraseMultipleBlockKs ooooononococnnncccnonccononnnonncnononcnonnnncnonncnonnncnnnno 4 18 NFCNandMedia copyPages n sense aa ata a oa ada adi a d acetat 4 19 NECNandMedia isBlockBad eee nenea ee n neea nana 4 20 NFCNandMedia markBlockBad eee nenea ee nana 4 21 Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor iii Paragraph Number 4 4 4 4 1 4 4 2 4 5 4 6 4 6 1 4 6 2 4 6 2 1 4 6 2 2 4 6 2 3 4 6 2 4 4 6 2 5 5 1 342 5 3 6 1 6 2 6 3 6 4 6 5 6 5 1 6 5 1 1 6 5 1 2 6 5 2 6 5 3 6 5 3 1 Contents Page Title Number Memory Manage Med iria ni is 4 22 A e So a a a Te 4 22 H ON 4 23 NES IDE DIE As AA 4 24 MFS Example User Manual ee f
29. ly in NAND physical device these data drivers can be declared in g_nandZipConfigBlockInfo variable in the file given below lt mqx gt source io nandflash_wl wearleveling hal ddi_nand_media_defination cpp Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 1 Using MQX NAND Flash Wear Leveling Module nand NandZipConfigBlockInfo_t g nand2ipConfigBlockInfo 3 Number of drives kDriveTypeData DRIVE_TAG DATA 10 0 0 kDriveTypeUnknon DRIVE_TAG DATA 10 0 La 10 kDriveTypeData DRIVE_TAG_DATA so Size of drive 0 r 20 Start block of drive he In this sample there are three drives two are data type one is unknown It means the follwing 10 19 1 drive Data type Use to hold data 3 drive Data type Use to hold data 0 9 20 99 Figure 4 1 Manually Pre defined 03 data Drivers Drives could be the following types Enum LogicalDriveType_t Description kDriveTypeData Public data drive kDriveTypeSystem System data drive kDriveTypeHidden Hidden data drive kDriveTypeUnknown Unknown data drive In the current WL version the WL only supports kDriveTypeData type Other types with its block range are ignored Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 2 Using MQX NAND Flash Wear Leveling Module 4 2 NAND Flash WL API NAND Flash WL dri
30. mature wear out on this map block whenever WL adds new section number to flash memory it always writes to the first available virtual page indicated by top section page index By using this strategy WL regularly touches all virtual pages in this block Every section contains a header on the first page data The most important fields in each header are e Signature for identifying a Zone Map or Phy Map e firstLBA Logical Block Address of first entry e totalEntries total number of entries in this section The assumption is that with one physical block 64 4 virtual pages 512 byte in each page it is possible to preserve all mapping information for physical NAND memory For example e For storing Phy Map Virtual page size 512 bytes and a block contains 64 4 virtual pages Section header 24 bytes 2 bits are used for indicating a block s status A block can present status of maximum 512 bytes 24 bytes 8bit 2 bit 64 4 pages 499 712 blocks 499 712 128KB in each block 61GB NAND flash device e For storing Zone Map Virtual page size 512 bytes and a block contains 64 4 virtual pages Section header 24 bytes Each entries contain a 24 bit physical block address Freescale MQX Flash File System User Guide Rev 1 4 6 Freescale Semiconductor MQX Wear Leveling Internal Software Flow A block can hold a maximum of 512 bytes 24 bytes 8bit 24 bit 64 4 pages 41 642 physical bl
31. n Map Get FREE block Mathematical convert Virtual sector address Virtual sector esta Look up iei Look up Virtual block page Sector Map Zone map block address Physical block Physical sector address offset E Figure 5 2 Internal Mechanism inside WL Module Phy Map holds a bitmap table that indicates the status of each block in the flash memory Zone Map stores a look up table for mapping the Vritual Block Address to the Physical Block Non Sequential Sector Map NSSM supplies a map to convert the logical sector offset to the physical sector offset in a Virtual Block One important aspect of the NSSM is that each NSSM is associated with a virtual block number not with a physical block This allows the data associated with the virtual block to move around the media as necessary As mentioned in the previous section the three maps Phy map Zone map and Non sequential sector map are both stored in RAM and preserved on flash memory for future re building purpose Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor MQX Wear Leveling Internal Functionality Freescale MQX Flash File System User Guide Rev 1 4 4 Freescale Semiconductor Chapter 6 MQX Wear Leveling Internal Software Flow This section describes software flow inside the WL Module 6 1 Initialize Flow Initialization steps are as shown below
32. n aa 4 25 User Interfaces pases ote tach odat nn en ns da 4 25 New Shell Commands e a Sa 4 25 fsoperi Commandant nain Ait 4 26 COSO COMA A A dacia data 4 27 nanderase COMI sia ori a pi Da ASE 4 27 Handrepair Commandes se galeata anal aa db 4 27 n nderasechip Commande da pg e i a Dl ga a anala Si 4 27 Chapter 5 MQX Wear Leveling Internal Functionality Roleor WI Module in NAND DOY did 5 1 Input and Output of WL Module 4 5 20 gta a a eS 5 1 Internal Mechanism inside WL Module sarita iii nd edi Da 5 2 Chapter 6 MQX Wear Leveling Internal Software Flow bia lize A O E NE 6 1 Redd S ctor Pl A AA he A A EA AA op daca 6 2 WEE CCOO nc iii cias 6 3 Shutdown FLOW issues tn ai 6 5 Zone Map Physical Map and Non sequential Sector Map Structure 6 5 Phy Map 3 cca aa il d al dal ii dl taie meets 6 7 Phy Map ii iiali ZAti ina ii ua Aa 6 9 Phy Map preserva i ee aa aa ean ee 6 9 ZONE MAD fale e e 22 ala aa ee PS aia a Naa 0 aid a alien 6 9 Non sequential Sector Map it e re 6 11 Prevent thrashing when switching from primary block to backup block 6 13 Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor Chapter 1 Introduction 1 1 Purpose This document describes the architecture of the MQX Wear Leveling module and its interface for the upper layer such as MFS and Read Write raw operations As a result of significant differences between NAND flash memory and NAND controller in F
33. n block No uint32_t blockAddress IN The temporary sector buffer SECTOR_BUFFER auxBuffer IN Indicate whether we should check the factory marking position NFCNandMedia currently does implement in lower layer bool checkFactoryMarkings OUT Read status RtStatus_t readStatus Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 20 Using MQX NAND Flash Wear Leveling Module 4 3 9 NFCNandMedia markBlockBad Description This function is used to mark a block as bad Prototype RtStatus_t NFCNandMedia markBlockBad IN Given block No uint32_t blockAddress IN The temporary sector buffer SECTOR_BUFFER pageBuffer IN The temporary sector auxiliary buffer SECTOR_BUFFER auxBuffer Freescale MQX Flash File System User Guide Rev 1 4 21 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 4 Memory Management Memory management is a useful module to manage profile allocated memory It enables both the developer and the user to know the amount of allocated free and leaked memory This module can be easily turned off by changing the definition NANDWL_MEM_LEAK_ DETECTION to zero When the definition is zero the NAND Flash WL module uses MQX standard allocator free memory mem_alloc free function instead of NAND Flash WL s function mm_alloc mm_free
34. nto the next free block in RBA NOTE A trust number TN informs that all maps have been flushed into the flash memory successfully It is located in the last two bytes of metadata byte 7 and byte 8 of every map block Normally the TN in Zone and Phy maps should be as follows e TN7ZoneMap 16 bit random number TNphyMap INZoneMap the Phy Map is always written to NAND flash before ZoneMap Freescale MQX Flash File System User Guide Rev 1 4 8 Freescale Semiconductor MQX Wear Leveling Internal Software Flow 6 5 1 1 Phy Map initialization Normally WL checks the trust number to find out whether all maps have been flushed If so WL will scan all blocks in RBA in flash memory to locate the block that holds the PhyMap table during initialization phase A valid PhyMap Block should have a valid signature and a consistent structure on each page If WL does not find a good Phy Map block it scans all blocks to build a new one 6 5 1 2 Phy Map preservation Whenever the Phy Map changes it is dirty WL flushes it to the flash memory 6 5 2 Zone Map Zone map contains a mapping table between Logical Block Address and Physical Block Address Logical Block 1 Physical Block 1 Logical Block 2 Physical Block 2 Logical Block 3 Physical Block 3 Logical Block N Physical Block N Logical NAND Flash memory Physical NAND Flash memory Figure 6 10 Zon
35. o enhance the search time a Red black tree is used to hold the non sequential maps Each node of the tree is a non sequential map whereby the key is related to the Virtual Block Address VBA of that map Since a Red black tree is a self balancing binary search tree searching time is optimized Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor MQX Wear Leveling Internal Software Flow de cin sis Figure 6 14 Non sequential Map in Red Black Tree Structure 6 5 3 1 Prevent thrashing when switching from primary block to backup block Since NSSM uses a backup block that contains the previous contents of the block primary one when the primary block becomes full the primary and backup are merged into a new block There are a few existing merge strategies as described below shortCircuitMerge When the primary block is full WL requests a new free physical block from the PhyMap and assigns it as a new primary block The backup block is erased and freed At this time the backup block points to the previous primary block Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor MQX Wear Leveling Internal Software Flow aged A Before ES Ge N S ON Q Ce AS ba 2 The same logical SS block VBA c i Erased and J Set free B After When primary Free Block bl
36. ock address 41 642 128KB in each block 5GB NAND flash device NOTE When the top section page index reaches the total virtual page in a block 64 4 it means that this map block is completely full WL relocates this block to the new one still in reserved area block This process is called consolidation Compared to the Zone and Phy Map a Non sequential Sector map is distributed in every virtual page spare area In case NFC_CFG PAGECNT 4 we have 64 4 virtual pages in one block 4 Virtual Page ssl Qe a Virtual Page O Virtual Page 0 de E Virtual Virtual re 63 4 page page 0 page 1 63 me p Flags In case ECC uses 8 bytes Block Reserved indicates for O4bits auto correctiion Bee use in Logical Logical that all ae Non Oxtf case Block Sector pages in ECC p 16bit Address Index 2 theblock 8bytes BAD 1 N byte andflas 3 bytes bytes are sorted h 1 byte logically 1 byte Figure 6 8 Organization of Non sequential Sector Map in Virtual Page Spare Area NOTE Generally the reserved block area RBA is expandable if there are bad blocks inside this area In this instance the reserved block area moves toward the higher block address and relocates any non map blocks which reside in RBA 6 5 1 Phy Map Phy map is responsible to get set a status of the specific physical block It stores the status of each block in the flash memory by u
37. ock is full completely Mapped to Mapped to Figure 6 15 ShortCircuitMerge for Non sequential Sector Map e quickMerge occurs if the system requests WL to flush all data to memory Merge happens when the primary block is not yet full but the number of sectors in backup is fitted to the primary only In this case WL will copy all remaining sectors in the backup block to the primary block After that the backup block is erased and freed Freescale MQX Flash File System User Guide Rev 1 4 14 Freescale Semiconductor MQX Wear Leveling Internal Software Flow Physical Sector N 1 Unused Physical Sector N Unused Backup Block Primary Block Primary Block Mapped to Re ae Mapped to 1 1 Vi i Mapped to y The same logical block VBA Figure 6 16 QuickMerge for Non sequential Sector Map mergeBlocksCore When the upper layer is writing to a sector if any error occurs that means that the block to which the sector belongs is bad so WL has to merge the backup block and primary block into a new block Finally the backup block is erased and the previous primary block is marked as bad Freescale MQX Flash File System User Guide Rev 1 4 15 Freescale Semiconductor MQX Wear Leveling Internal Software Flow Physical Sector N 1
38. or Flow NAND WL IF Zone Map Phy Map Non sequential Sector Map l l N I 7 Get relative Physical Block Number o of Virtual Block Number A of Logical Sector Number __Assign a new free physical block _ if does not find out Return OxFF buffer when can t get _ _ _ Physical Sector Number N D relative Physical Block Return the relative MA A Physical Block Number Return a new free Get Physical Sector Offset of Virtual Sector Number of Logical Sector Number within the relative Physical Block Number A There is something wrong Physical Block Number l Return relative Physical Sector Offset Figure 6 3 WL Read Sector Sequence Diagram In this sequence diagram Step 1 If MES wants to read data from a logical sector it passes a logical sector address to the NAND WL IF of the NAND driver WL needs to make sure that a given logical sector is not out of bounds block number and a virtual block offset Step 2 The NAND WL IF converts the input logical sector number mathematically into a virtual Step 3 If the Zone map object is loaded or built from the initialization phase the NAND WL IF searches the map to figure out a relative physical block of this virtual block If the physical block cannot be found that means that no physical block was assigned to this virtual block and that a Freescale MQX Flash File
39. pplications to run along with the old ones which are used to access raw data on NAND physical Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 3 Architecture Overview App with Filesystem access capability fopen nandflash_wl IOCTL to enable WL Old NAND Apps MFS MQX File System Partition Manager Device Driver fopen nandflash Legend Old Nandflash driver with RAW operations No modification Old Read Write Erase IOCTL operation NAND Flash Controller Hardware NAND Physical Figure 3 3 New NAND Architecture with Wear Leveling Capability In this figure e NAND flash driver Old NAND flash driver provides read write raw function for all legacy applications Freescale MQX Flash File System User Guide Rev 1 4 4 Freescale Semiconductor Architecture Overview New NAND flash driver with Wear Leveling supplies read write with wear leveling capability for upper layers such as MFS Wear Leveling functions this module contains all mapping mechanisms between Virtual Page Address and Physical Page Address It also maintains mapping tables on flash memory and RAM e NAND Flash Controller NFC Read Write Erase IOCTL operation old NFC s function for read write erase directly with NEC hardware These functions work only with Virtual Page data ReadPage WriteP
40. reescale CPUs this document only addresses a Wear Leveling solution for the CPU that is compatible with the NAND flash memory NFC hardware The MQX Wear Leveling module currently supports all platforms on MQX RTOS that have the NAND flash device 1 2 Wearout Problem on Flash Memory Flash memory is a non volatile memory that can be easily erased and reprogrammed when compared to some predecessor memories such as EEPROM Flash memory is popular as a result of 1ts small physical size light weight low power consumption high shock resistance and fast read performance Currently there are two types of flash memory NAND flash memory and NOR flash memory NAND flash memory is organized as an array of blocks Each block contains 32 to 64 pages where a page 1s the smallest unit for read and write operation On the other hand to erase the input must be a block rather than a pages On the other hand NAND flash memory has a limited number of program erase cycles typically known as P E cycles Today the most available flash products in the market are designed to endure around 100 000 P E cycles before the cells become unreliable This phenomenon is called memory wear or wearout 1 3 Solution to Avoid Wearout Issues To control the wear out problem and to extend NAND flash lifetime a method named wear leveling is used Wear leveling tries to distribute every program erase operations equally on each block in the flash drive The equal distri
41. sing a bitmap entry Each entry in this map uses 01 bit to represent three different states Of a block e Block is used occupied or bad e Block is free Freescale MQX Flash File System User Guide Rev 1 4 7 Freescale Semiconductor AN MQX Wear Leveling Internal Software Flow These entries are encapsulated with a header and write to NEXT available virtual page in specific PhyMap block Used 01 bit for Each Virtual page section will store each entries MAX_ENTRIES_PER_PAGE entries used free and bad good block ee top section page Idx 1 Current Idx Pos Block stores PhyMap Pe NAND Flash Blocks asn memory Index of Section contains entry for LBAi Phy bitmap LBAi Total Entries Per Section entries Figure 6 9 Phy Map Organization in Memory and Flash In this figure e Each Physical Virtual Page stores a maximum of MAX_ENTRIES_PER_PAGE entries WL encapsulates these entries into a section by padding a header before flushing to flash memory e Current index position indicates that the next free non map block can be allocated This position is helpful whenever a user wants to request a new block for writing e Top section page index indicates the section of the next free virtual page that can be stored This index continuously increments toward the higher address when it reaches a total page number WL will consolidate all sections of this map i
42. ss freescale com SalesTermsandConditions Freescale the Freescale logo Kinetis and ColdFire are trademarks of Freescale Semiconductor Inc Reg U S Pat 8 Tm Off Vybrid and Tower are trademarks of Freescale Semiconductor Inc All other product or service names are the property of their respective owners O 2014 Freescale Semiconductor Inc 2 freescale Paragraph Number 1 1 1 2 1 3 1 4 2 1 2 2 3 1 3 2 4 1 4 2 4 2 1 4 2 2 4 2 3 4 2 4 4 2 5 4 2 6 4 2 7 4 2 8 4 2 9 4 2 10 4 3 4 3 1 4 3 2 4 3 3 4 3 4 4 3 5 4 3 6 4 3 7 4 3 8 4 3 9 Contents Page Title Number Chapter 1 Introduction PUT POSE nant ni ren eta aa Cl eat 1 1 Wearout Problem on Flash Memory suite denis adrien idas 1 1 Solution to Avoid Wearout Issues 1 1 Outline sc AD A a da E ca oaia ua 1 2 Chapter 2 Abbreviations Acronyms and References Abbreviations ACTONVIMS sic ie casca anca ata a ai dai nana dana ad a da aa 2 1 References a iol etre ad en io a endo 2 2 Chapter 3 Architecture Overview Old NAND Flash Architecture cosido HN ee de ta a 3 1 New Architecture with Wear Leveling WL Capability mean 3 3 Chapter 4 Using MQX NAND Flash Wear Leveling Module Configure Pre defined Data Drive Layos Aa 4 1 INA NDS Hash WERE dd Ii 0 bat ie ad 4 3 10 nandflash owl mstalii aia 000 0 a ol 0 6 i d pot 4 3 _10_nandflash_wl_uninstall ee nenea eee nene nana 4 4 Dac Iasi MI OPEN nc id ii 4 5 A10 nandi
43. through each page as a minimum unit and erase on each blocks NOR NOR flash memory lets users be able to random access in every bytes in flash memory Block A smallest erasable unit in NAND device Page A smallest programmable unit in NAND device PhysicalBlock The address of physical block in memory Address PBA Virtual Block Since we used entire flash memory for wear leveling the VBA is same as LBA This address points to a Address logical address which are mapped to specific PBA VBA Logical Block Address LBA Wearout A circumstance occurs when a block is uneraseable or a page cannot be written Wear leveling Wear leveling is a process that helps reduce premature wear in NAND flash devices Bad Block A block resist in NAND flash memories that cannot be erase or write any more Metadata Data is used by NAND driver to carry a specific information Sparedata An area is typically used for ECC wear leveling and other software overhead functions NFC NAND Flash Controller NAND driver A driver which is responsible for initializing and handling read write erase through NAND memories ONFI Open NAND Flash Interface Error A code or checksum for automatically correcting purpose An ECC stores in Metadata sparedata of each Correcting pages Code ECC Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor Abbreviations Acronyms and References Table 2 1 A
44. ule 4 6 2 2 fsclose Command This command is used to close NAND flash memory and shutdown initialized wear leveling module 4 6 2 3 nanderase Command This command is used to erase all blocks which are defined as Data drive These blocks are erased by wear leveling module not NFC directly 4 6 2 4 nandrepair Command This command is used to repair all blocks in defined Data drive Random data will be written to these blocks included the spare area and their status is also checked The wear leveling module will rebuild necessary maps because they were erased while the Data drive is being repaired 4 6 2 5 nanderasechip Command This command is used to erase all blocks in NAND flash memory These blocks are erased directly by the NFS ioctl The wear leveling module is not installed NOTE e First time users of the MFS NAND Flash example should run nanderasechip command first If the data in the spare area which holds metadata of each sector is cluttered it will cause the core to malfunction With incorrect data the core will build incorrect maps and critical errors may occur e To change the size of the default data drive or the structure of the NAND media please make sure they were declared in g_nandZipConfigBlockInfo variable Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor 27 Using MQX NAND Flash Wear Leveling Module Freescale MQX Flash File System User
45. ver provides an interface for upper layer such as MFS and read write raw operations Its prototypes are described as shown below 4 2 1 _io_nandflash_wil_ install Description This function is responsible for installing the main functions of nandflash memory _io_nandflash_wl_open _io_nandflash_ wl close _io_nandflash wl_ read _io nandflash_wl_ write _io nandflash_wl_ioctl _io nandflash_wl_uninstall Prototype mqx_uint _io_nandflash_wl_install IN The initialization structure for the device NANDFLASH_INIT_STRUCT _PTR_ init_ptr Freescale MQX Flash File System User Guide Rev 1 4 3 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 2 2 _io_nandflash_wl_uninstall Description This function is used to uninstall the nandflash memory and free all unused allocated memory Prototype _mqx_int _io_nandflash_wl_uninstall IN The IO device structure for the device IO_DEVICE_STRUCT_PTR io_dev_ptr Freescale MQX Flash File System User Guide Rev 1 4 Freescale Semiconductor Using MQX NAND Flash Wear Leveling Module 4 2 3 _io_nandflash_wl_open Description This function is used to open and initialize nand flash driver supported wear leveling feature Depending on the input argument the core of the driver is either built or ignored Prototype _mqx_int _io_nandflash_wl_open IN the file handle for the device being opened
46. written to the primary block If a logical sector is not present in the primary block it can be read from the backup block When the primary block becomes full the primary and backup are merged into a new block Merging takes the most recent version of each logical sector from either the primary or backup and writes it to the new block Another important aspect of the NSSM is that each NSSM is associated with a virtual block number not a physical block This allows the data associated with the virtual block to move around on the media as necessary Freescale MQX Flash File System User Guide Rev 1 4 11 Freescale Semiconductor MQX Wear Leveling Internal Software Flow Logical Sector 1 Logical Sector 2 Logical Sector 3 Logical Sector N Logical Block Physical Block Figure 6 13 Mapping between Logical Sector lt gt Physical Sector Each block holds a non sequential map in the spare area of every page Whenever upper layer requests to read or write on a given sector WL will calculate a virtual block that contains a sector After that WL scans the spare area of all pages of this virtual block to build up a non sequential sector map To boost performance WL uses specific caching mechanism to improve speed when looking up a logical sector in one block Similar to Zone Map only a few maps are loaded into memory WL uses LRU strategy for every cache missed map In addition t
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