X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=doc%2FREADME.nand;h=8eedb6c4d70a1e417a0677ed487ded7f6239c961;hb=ec79d33b2c41ee8b6d1354cc0910217b769c5036;hp=5c31845a94c0a016f6c8a8021fea8a0639497650;hpb=19bf91f9628f80a55d4f171df71041574882b3d6;p=u-boot diff --git a/doc/README.nand b/doc/README.nand index 5c31845a94..8eedb6c4d7 100644 --- a/doc/README.nand +++ b/doc/README.nand @@ -57,14 +57,9 @@ Commands: Print information about all of the NAND devices found. nand read addr ofs|partition size - Read `size' bytes from `ofs' in NAND flash to `addr'. If a page - cannot be read because it is marked bad or an uncorrectable data - error is found the command stops with an error. - - nand read.jffs2 addr ofs|partition size - Like `read', but the data for blocks that are marked bad is read as - 0xff. This gives a readable JFFS2 image that can be processed by - the JFFS2 commands such as ls and fsload. + Read `size' bytes from `ofs' in NAND flash to `addr'. Blocks that + are marked bad are skipped. If a page cannot be read because an + uncorrectable data error is found, the command stops with an error. nand read.oob addr ofs|partition size Read `size' bytes from the out-of-band data area corresponding to @@ -73,17 +68,15 @@ Commands: for bad blocks or ECC errors. nand write addr ofs|partition size - Write `size' bytes from `addr' to `ofs' in NAND flash. If a page - cannot be written because it is marked bad or the write fails the - command stops with an error. - - nand write.jffs2 addr ofs|partition size - Like `write', but blocks that are marked bad are skipped and the - is written to the next block instead. This allows writing writing - a JFFS2 image, as long as the image is short enough to fit even - after skipping the bad blocks. Compact images, such as those - produced by mkfs.jffs2 should work well, but loading an image copied - from another flash is going to be trouble if there are any bad blocks. + Write `size' bytes from `addr' to `ofs' in NAND flash. Blocks that + are marked bad are skipped. If a page cannot be read because an + uncorrectable data error is found, the command stops with an error. + + As JFFS2 skips blocks similarly, this allows writing a JFFS2 image, + as long as the image is short enough to fit even after skipping the + bad blocks. Compact images, such as those produced by mkfs.jffs2 + should work well, but loading an image copied from another flash is + going to be trouble if there are any bad blocks. nand write.oob addr ofs|partition size Write `size' bytes from `addr' to the out-of-band data area @@ -93,8 +86,8 @@ Commands: Configuration Options: - CFG_CMD_NAND - A good one to add to CONFIG_COMMANDS since it enables NAND support. + CONFIG_CMD_NAND + Enables NAND support and commmands. CONFIG_MTD_NAND_ECC_JFFS2 Define this if you want the Error Correction Code information in @@ -102,110 +95,25 @@ Configuration Options: CONFIG_MTD_NAND_ECC_YAFFS would be another useful choice for someone to implement. - CFG_MAX_NAND_DEVICE + 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 CFG_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 NAND_MAX_CHIPS 1 - + CONFIG_SYS_NAND_MAX_CHIPS + The maximum number of NAND chips per device to be supported. 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: -CFG_NAND_LEGACY, which has to be defined in the board config file if -that board uses legacy code. +The current NAND implementation is based on what is in recent +Linux kernels. The old legacy implementation has been removed. -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. - -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 @@ -215,12 +123,6 @@ JFFS2 related commands: using both the new code which is able to skip bad blocks "nand erase clean" additionally writes JFFS2-cleanmarkers in the oob. - "nand write.jffs2" - like "nand write" but skip found bad eraseblocks - - "nand read.jffs2" - like "nand read" but skip found bad eraseblocks - Miscellaneous and testing commands: "markbad [offset]" create an artificial bad block (for testing bad block handling)