As was discussed between Ricard Wanderlöf, David Woodhouse, Artem
Bityutskiy and me, the current API for reading/writing OOB is confusing.
The thing that introduces confusion is the need to specify ops.len
together with ops.ooblen for reads/writes that concern only OOB not data
area. So, ops.len is overloaded: when ops.datbuf != NULL it serves to
specify the length of the data read, and when ops.datbuf == NULL, it
serves to specify the full OOB read length.
The patch inlined below is the slightly updated version of the previous
patch serving the same purpose, but with the new Artem's comments taken
into account.
Artem, BTW, thanks a lot for your valuable input!
Signed-off-by: Vitaly Wool <vwool@ru.mvista.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
The raw read/write access to NAND (without ECC) has been changed in the
NAND rework. Expose the new way - setting the file mode via ioctl - to
userspace. Also allow to read out the ecc statistics information so userspace
tools can see that bitflips happened and whether errors where correctable
or not. Also expose the number of bad blocks for the partition, so nandwrite
can check if the data fits into the parition before writing to it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Hopefully the last iteration on this!
The handling of out of band data on NAND was accompanied by tons of fruitless
discussions and halfarsed patches to make it work for a particular
problem. Sufficiently annoyed by I all those "I know it better" mails and the
resonable amount of discarded "it solves my problem" patches, I finally decided
to go for the big rework. After removing the _ecc variants of mtd read/write
functions the solution to satisfy the various requirements was to refactor the
read/write _oob functions in mtd.
The major change is that read/write_oob now takes a pointer to an operation
descriptor structure "struct mtd_oob_ops".instead of having a function with at
least seven arguments.
read/write_oob which should probably renamed to a more descriptive name, can do
the following tasks:
- read/write out of band data
- read/write data content and out of band data
- read/write raw data content and out of band data (ecc disabled)
struct mtd_oob_ops has a mode field, which determines the oob handling mode.
Aside of the MTD_OOB_RAW mode, which is intended to be especially for
diagnostic purposes and some internal functions e.g. bad block table creation,
the other two modes are for mtd clients:
MTD_OOB_PLACE puts/gets the given oob data exactly to/from the place which is
described by the ooboffs and ooblen fields of the mtd_oob_ops strcuture. It's
up to the caller to make sure that the byte positions are not used by the ECC
placement algorithms.
MTD_OOB_AUTO puts/gets the given oob data automaticaly to/from the places in
the out of band area which are described by the oobfree tuples in the ecclayout
data structre which is associated to the devicee.
The decision whether data plus oob or oob only handling is done depends on the
setting of the datbuf member of the data structure. When datbuf == NULL then
the internal read/write_oob functions are selected, otherwise the read/write
data routines are invoked.
Tested on a few platforms with all variants. Please be aware of possible
regressions for your particular device / application scenario
Disclaimer: Any whining will be ignored from those who just contributed "hot
air blurb" and never sat down to tackle the underlying problem of the mess in
the NAND driver grown over time and the big chunk of work to fix up the
existing users. The problem was not the holiness of the existing MTD
interfaces. The problems was the lack of time to go for the big overhaul. It's
easy to add more mess to the existing one, but it takes alot of effort to go
for a real solution.
Improvements and bugfixes are welcome!
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The nand_oobinfo structure is not fitting the newer error correction
demands anymore. Replace it by struct nand_ecclayout and fixup the users
all over the place. Keep the nand_oobinfo based ioctl for user space
compability reasons.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The info structure for out of band data was copied into
the mtd structure. Make it a pointer and remove the ability
to set it from userspace. The position of ecc bytes is
defined by the hardware and should not be changed by software.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
MTD clients are agnostic of FLASH which needs ECC suppport.
Remove the functions and fixup the callers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
At least two flashes exists that have the concept of a minimum write unit,
similar to NAND pages, but no other NAND characteristics. Therefore, rename
the minimum write unit to "writesize" for all flashes, including NAND.
Signed-off-by: Joern Engel <joern@wh.fh-wedel.de>
'oobavail' parameter of mtd_info structure is now propagated to the MTD
partitions
Signed-off-by: Vitaly Wool <vwool@ru.mvista.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Don't assume eraseblock size is power of 2.
Dataflash can have aligned eraseblock size.
From: Peter Menzebach <pm-mtd@mw-itcon.de>
Acked-by: Artem B. Bityutskiy <dedekind@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This enables support for reading, writing and locking so called
"Protection Registers" present on some flash chips.
A subset of them are pre-programmed at the factory with a
unique set of values. The rest is user-programmable.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
