diff options
Diffstat (limited to 'doc/README.nand')
| -rw-r--r-- | doc/README.nand | 109 |
1 files changed, 13 insertions, 96 deletions
diff --git a/doc/README.nand b/doc/README.nand index fc62f92..bb72289 100644 --- a/doc/README.nand +++ b/doc/README.nand @@ -98,83 +98,10 @@ Configuration Options: CONFIG_SYS_MAX_NAND_DEVICE The maximum number of NAND devices you want to support. -NAND Interface: - - #define NAND_WAIT_READY(nand) - Wait until the NAND flash is ready. Typically this would be a - loop waiting for the READY/BUSY line from the flash to indicate it - it is ready. - - #define WRITE_NAND_COMMAND(d, adr) - Write the command byte `d' to the flash at `adr' with the - CLE (command latch enable) line true. If your board uses writes to - different addresses to control CLE and ALE, you can modify `adr' - to be the appropriate address here. If your board uses I/O registers - to control them, it is probably better to let NAND_CTL_SETCLE() - and company do it. - - #define WRITE_NAND_ADDRESS(d, adr) - Write the address byte `d' to the flash at `adr' with the - ALE (address latch enable) line true. If your board uses writes to - different addresses to control CLE and ALE, you can modify `adr' - to be the appropriate address here. If your board uses I/O registers - to control them, it is probably better to let NAND_CTL_SETALE() - and company do it. - - #define WRITE_NAND(d, adr) - Write the data byte `d' to the flash at `adr' with the - ALE and CLE lines false. If your board uses writes to - different addresses to control CLE and ALE, you can modify `adr' - to be the appropriate address here. If your board uses I/O registers - to control them, it is probably better to let NAND_CTL_CLRALE() - and company do it. - - #define READ_NAND(adr) - Read a data byte from the flash at `adr' with the - ALE and CLE lines false. If your board uses reads from - different addresses to control CLE and ALE, you can modify `adr' - to be the appropriate address here. If your board uses I/O registers - to control them, it is probably better to let NAND_CTL_CLRALE() - and company do it. - - #define NAND_DISABLE_CE(nand) - Set CE (Chip Enable) low to enable the NAND flash. - - #define NAND_ENABLE_CE(nand) - Set CE (Chip Enable) high to disable the NAND flash. - - #define NAND_CTL_CLRALE(nandptr) - Set ALE (address latch enable) low. If ALE control is handled by - WRITE_NAND_ADDRESS() this can be empty. - - #define NAND_CTL_SETALE(nandptr) - Set ALE (address latch enable) high. If ALE control is handled by - WRITE_NAND_ADDRESS() this can be empty. - - #define NAND_CTL_CLRCLE(nandptr) - Set CLE (command latch enable) low. If CLE control is handled by - WRITE_NAND_ADDRESS() this can be empty. - - #define NAND_CTL_SETCLE(nandptr) - Set CLE (command latch enable) high. If CLE control is handled by - WRITE_NAND_ADDRESS() this can be empty. - -More Definitions: - - These definitions are needed in the board configuration for now, but - may really belong in a header file. - TODO: Figure which ones are truly configuration settings and rename - them to CONFIG_SYS_NAND_... and move the rest somewhere appropriate. - - #define SECTORSIZE 512 - #define ADDR_COLUMN 1 - #define ADDR_PAGE 2 - #define ADDR_COLUMN_PAGE 3 - #define NAND_ChipID_UNKNOWN 0x00 - #define NAND_MAX_FLOORS 1 - #define CONFIG_SYS_NAND_MAX_CHIPS 1 - - #define CONFIG_SYS_DAVINCI_BROKEN_ECC + CONFIG_SYS_NAND_MAX_CHIPS + The maximum number of NAND chips per device to be supported. + + CONFIG_SYS_DAVINCI_BROKEN_ECC Versions of U-Boot <= 1.3.3 and Montavista Linux kernels generated bogus ECCs on large-page NAND. Both large and small page NAND ECCs were incompatible with the Linux davinci git tree (since @@ -186,27 +113,17 @@ More Definitions: NOTE: ===== -We now use a complete rewrite of the NAND code based on what is in -2.6.12 Linux kernel. - -The old NAND handling code has been re-factored and is now confined -to only board-specific files and - unfortunately - to the DoC code -(see below). A new configuration variable has been introduced: -CONFIG_NAND_LEGACY, which has to be defined in the board config file if -that board uses legacy code. - -The necessary changes have been made to all affected boards, and no -build breakage has been introduced, except for NETTA and NETTA_ISDN -targets from MAKEALL. This is due to the fact that these two boards -use JFFS, which has been adopted to use the new NAND, and at the same -time use NAND in legacy mode. The breakage will disappear when the -board-specific code is changed to the new NAND. +The current NAND implementation is based on what is in recent +Linux kernels. The old legacy implementation has been disabled, +and will be removed soon. -As mentioned above, the legacy code is still used by the DoC subsystem. -The consequence of this is that the legacy NAND can't be removed from -the tree until the DoC is ported to use the new NAND support (or boards -with DoC will break). +If you have board code which used CONFIG_NAND_LEGACY, you'll need +to convert to the current NAND interface for it to continue to work. +The Disk On Chip driver is currently broken and has been for some time. +There is a driver in drivers/mtd/nand, taken from Linux, that works with +the current NAND system but has not yet been adapted to the u-boot +environment. Additional improvements to the NAND subsystem by Guido Classen, 10-10-2006 |