This patch refactors elm_load_syndrome() to make it scalable for newer
ECC schemes by removing scheme specific macros (like ECC_BYTES*xx),
and instead using ECC control information passed during elm_config.
Signed-off-by: NPekon Gupta <pekon@ti.com>
Reviewed-by: NEzequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>

ELM hardware engine is used by BCH ecc-schemes for detecting and locating ECC
errors. This patch adds the following checks for ELM hardware engine:

 - ELM internal buffers are of 1K,
   so it cannot process data with ecc-step-size > 1K.

 - ELM engine can execute upto maximum of 8 threads in parallel,
   so in *page-mode* (when complete page is processed in single iteration),
   ELM cannot support ecc-steps > 8.
Signed-off-by: NPekon Gupta <pekon@ti.com>
Reviewed-by: NEzequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>

In case the driver is not probed - due to config mismatches or errors
in the DTS files - dev_get_drvdata() returns NULL, leading to an Ooops
during boot.

Make elm_config() return an error in such cases to propagate the error
up to the user, so it can fall back to software mode.
Signed-off-by: NDaniel Mack <zonque@gmail.com>
Acked-by: NPeter Korsgaard <jacmet@sunsite.dk>
Signed-off-by: NArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

ELM module can be used for hardware error correction of BCH 4 & 8 bit.
ELM module functionality is verified by checking the availability of
handle for ELM module in device tree. Hence supporting
1. ELM module available, BCH error correction done by ELM module. Also
support read & write page in one shot by adding custom read_page and
write_page methods. This helps in optimizing code for NAND flashes with
page size less than 4 KB.
2. If ELM module not available fall back to software BCH error
correction support.

New structure member is added to omap_nand_info
1. "is_elm_used" to know the status of whether the ELM module is used for
   error correction or not.
2. "elm_dev" device pointer to elm device on detection of ELM module.

Also being here update the device tree documentation of gpmc-nand for
adding optional property elm_id.

Note:
ECC layout uses 1 extra bytes for 512 byte of data to handle erased
pages. Extra byte programmed to zero for programmed pages. Also BCH8
requires 14 byte ecc to maintain compatibility with RBL ECC layout.
This results a common ecc layout across RBL, U-boot & Linux with BCH8.
Signed-off-by: NPhilip Avinash <avinashphilip@ti.com>
Signed-off-by: NArtem Bityutskiy <artem.bityutskiy@linux.intel.com>

The ELM hardware module can be used to speedup BCH 4/8/16 ECC scheme
error correction.
For now only 4 & 8 bit support is added
Signed-off-by: NPhilip Avinash <avinashphilip@ti.com>
Signed-off-by: NArtem Bityutskiy <artem.bityutskiy@linux.intel.com>