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. 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. 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. The nand driver implements different possibilities for placement of filesystem data in the spare area,. 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. The useecc member controls the ecc and placement function. This is not recommended and available for testing and diagnosis only. The oobfree array defines the areas in the spare area which can be used for automatic placement. More than one area can be defined. For writes the caller must provide a spare area buffer along with the data buffer.
The driver stores the result of the ecc check for each tuple in the spare buffer. The storage sequence is:. Automatic placement uses the built in defaults to place the ecc bytes in the spare area. 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. Filesystems must be aware of the NAND peculiarities and restrictions.
The consecutive writes to a page, before erasing it again, are restricted to 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. 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. 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. These constants are defined in rawnand. They are OR-ed together to describe the chip functionality:. These constants describe the requested hardware access function when the boardspecific hardware control function is called:. 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. Must only be provided if an hardware ECC is available. Should return a positive number representing the number of corrected bitflips, -EBADMSG if the number of bitflips exceed ECC strength, or any other error code if the error is not directly related to correction.
This function should hide the specific layout used by the ECC controller and consider the passed data as contiguous in-band and out-of-band data. ECC controller is responsible for doing the appropriate transformations to adapt to its specific layout e. Most modern controllers have internal timings control logic, and in this case, the controller driver can ignore this field.
When an operation cannot be handled as is by the NAND controller, it will be split by the parser into sub-operations which will be passed to the controller driver. A pattern is a list of elements, each element reprensenting one instruction with its constraints. Usually, this is where you put single instruction patterns.
Typically used to choose the appropriate ECC configuration and allocate associated resources. This hook is optional. Various chip options. See the defines for further explanation. If unset, the default reset interface configuration must be used. Bad block table specific options. All options used here must come from bbm.
Currently selected target. The ECC step required by the ecc. Returns the pre-allocated page buffer after invalidating the cache.
This function should be used by drivers that do not want to allocate their own bounce buffer and still need such a buffer for specific operations most commonly when reading OOB data only. Each function has a short description which is marked with an [XXX] identifier. Deselect the currently selected NAND target.
The result of operations executed on chip after the target has been deselected is undefined. This function does a raw data read on the bus. This function does a raw data write on the bus. Helper function designed to ease integration of NAND controller drivers that only support a limited set of instruction sequences.
Returns 0 on success, a negative error code otherwise. This is wrong as address instructions might be split. This is wrong as instructions might be split. This is wrong as data instructions might be split.
Check if a data buffer and its associated ECC and OOB data contains only 0xff pattern, which means the underlying region has been erased and is ready to be programmed. In case of success, the passed buffers are filled with 0xff. When fixing bitflips, ECC engines will report the number of errors per chunk, and the NAND core infrastructure expect you to return the maximum number of bitflips for the whole page.
This is why you should always use this function on a single chunk and not on the whole page. This is a raw page read, ie. This is a raw page write, ie.
Monolithic means we are requesting all the relevant data main plus eventually OOB to be sent over the bus and effectively programmed into the NAND chip arrays in a single operation.
This fills out all the uninitialized function pointers with the defaults. This chapter contains the autogenerated documentation of the NAND driver internal functions. Returns an integer that corresponds to the page offset within a block, for a page that is used to store bad block markers. Checks if the region is secured by comparing the offset and size with the list of secure regions obtained from DT.
Returns true if the region is secured else false. Check, if the device is write protected. 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 bad block table contains all bad block information of the device which can consist of multiple chips. A bad block table is used per chip and contains the bad block information for this particular chip. The bad block table is located at a fixed offset in the chip device.
This applies to various DiskOnChip devices. The bad block table is automatically placed and detected either at the end or at the beginning of a chip device. The bad block table is mirrored on the chip device to allow updates of the bad block table without data loss. 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.
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 default bad block table options are. The options define most of the table properties. Use the predefined constants from rawnand.
If this option is not set then a per device bad block table is used. 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.
The table can either be located in the first or the last good blocks 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. For mirrored bad block tables different patterns are mandatory. Usually this is done only once if a new chip is found. This allows the update of the bad block table s in case a block has to be marked bad due to wear.
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.
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. 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. The nand driver implements different possibilities for placement of filesystem data in the spare area,. 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. The useecc member controls the ecc and placement function. This is not recommended and available for testing and diagnosis only. The eccpos array holds the byte offsets in the spare area where the ecc codes are placed. The oobfree array defines the areas in the spare area which can be used for automatic placement.
More than one area can be defined. For writes the caller must provide a spare area buffer along with the data buffer. The driver stores the result of the ecc check for each tuple in the spare buffer. The storage sequence is:. Automatic placement uses the built in defaults to place the ecc bytes in the spare area.
Filesystems must be aware of the NAND peculiarities and restrictions. The consecutive writes to a page, before erasing it again, are restricted to writes, depending on the manufacturers specifications. 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.
These constants are defined in nand. They are ored together to describe the chip functionality. They are ored together to describe the functionality. These constants describe the requested hardware access function when the boardspecific hardware control function is called. 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. Must only be provided if an hardware ECC is available. Also used to write command and address. Return with the bus width. See the defines for further explanation. All options used here must come from bbm. If unknown, set to zero. It is the recommended ECC step size, if known; if unknown, set to zero. Each function has a short description which is marked with an [XXX] identifier.
This feature is not supported in many NAND parts. Implementing 'lock' feature by making use of 'unlock', for now. It fills out all the uninitialized function pointers with the defaults and scans for a bad block table if appropriate. This fills out all the uninitialized function pointers with the defaults.
The bad block table memory is allocated here. This chapter contains the autogenerated documentation of the NAND driver internal functions.
This is the default implementation, which can be overridden by a hardware specific driver. It provides the details for writing a bad block marker to a block. This function performs the generic NAND bad block marking steps i.
Check, if the device is write protected. The function expects, that the device is already selected. Check, if the block is bad. Either by reading the bad block table or calling of the scan function.
Send command to NAND device. This function is used for small page devices Bytes per page. This is the version for the new large page devices. We don't have the separate regions as we have in the small page devices. Wait for command done. May happen when in panic and trying to write an oops through mtdoops.
This applies to erase and program only. The hw generator calculates the error syndrome automatically. Therefore we need a special oob layout and handling. Used when performing writes in interrupt context, this may for example be called by mtdoops when writing an oops while in panic. Check for a pattern at the given place. Read the bad block table for all chips starting at a given page. We assume that the bbt bits are in consecutive order. May quit on the first non-ECC error. Read the bad block table s for all chips starting at a given page.
Read the bad block table by searching for a given ident pattern. Search is preformed either from the beginning up or from the end of the device downwards. The search starts always at the start of a block. This is necessary to provide support for certain DOC devices.
Update is necessary if one of the tables is missing or the version nr. The regions are identified by the mark 0x Steven J. A lot of users have provided bugfixes, improvements and helping hands for testing. Thanks a lot. Table of Contents 1. Introduction 2. Known Bugs And Assumptions 3.
Basic board driver Basic defines Partition defines Hardware control function Device ready function Init function Exit function 5. Advanced board driver functions Multiple chip control Hardware ECC support Functions and constants Hardware ECC with syndrome calculation Bad block table support Flash based tables User defined tables Spare area auto placement Placement defined by fs driver Automatic placement Spare area autoplacement default schemes byte pagesize byte pagesize byte pagesize 6.
Filesystem support 7. Tools 8. Constants Chip option constants Constants for chip id table Constants for runtime options ECC selection constants Hardware control related constants Bad block table related constants 9.
Chapter 1. Chapter 2. Known Bugs And Assumptions. Chapter 3. Documentation hints. Function identifiers [XXX]. Struct member identifiers [XXX]. Chapter 4. Basic board driver. Basic defines. Partition defines. Hardware control function. Device ready function.
Init function. Exit function. Chapter 5. Advanced board driver functions. Table of Contents Multiple chip control Hardware ECC support Functions and constants Hardware ECC with syndrome calculation Bad block table support Flash based tables User defined tables Spare area auto placement Placement defined by fs driver Automatic placement Spare area autoplacement default schemes byte pagesize byte pagesize byte pagesize.
Multiple chip control. Hardware ECC support. Functions and constants. Hardware ECC with syndrome calculation. Bad block table support. 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. 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.
Flash based tables. 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. Number of bits per block The supported number of bits is 1, 2, 4, 8. 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.
Note: Write support should only be enabled for mirrored tables with version control. Number of reserved blocks For automatic placement some blocks must be reserved for bad block table storage. Spare area auto placement. Placement defined by fs driver Automatic placement. Placement defined by fs driver. Automatic placement. Spare area autoplacement default schemes. This applies only to the first page in a block. In the remaining pages this byte is reserved 0x06 Autoplace 2 0x07 Autoplace 3.
Offset Content Comment 0x00 ECC byte 0 Error correction code byte 0 of the lower Byte data in this page 0x01 ECC byte 1 Error correction code byte 1 of the lower Bytes of data in this page 0x02 ECC byte 2 Error correction code byte 2 of the lower Bytes of data in this page 0x03 ECC byte 3 Error correction code byte 0 of the upper 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. In the remaining pages this byte is reserved 0x06 ECC byte 4 Error correction code byte 1 of the upper Bytes of data in this page 0x07 ECC byte 5 Error correction code byte 2 of the upper Bytes of data in this page 0x08 - 0x0F Autoplace 0 - 7.
Offset Content Comment 0x00 Bad block marker If any bit in this byte is zero, then this block is bad. Chapter 6. Filesystem support.
0コメント