[PATCH v4 0/2] MTK Smart Device Gen1 NAND Driver

Jorge Ramirez-Ortiz
2016-04-29T16:17:50Z

Fixes/Changes on v4 relative to:
--------------------------------

tree : https://github.com/bbrezillon/linux-0day
branch : nand/ecclayout
commit :
'commit "mtd: kill the nand_ecclayout struct"'
Author: Boris Brezillon <boris.brezillon@free-electrons.com>
Date: Thu Feb 4 10:16:18 2016 +0100
Patch v4
--------
mtd: mediatek: device tree docs for MTK Smart Device Gen1 NAND
- nand-on-flash-bbt, nand-ecc-mode, nand-ecc-step-size and
nand-ecc-strength are now optional parameters
- spare-per-sector removed from DT settings.
- extend documentation.

mtd: mediatek: driver for MTK Smart Device Gen1 NAND
- rename functions (semantic issues).
- add lock to ECC engine.
- rework ECC interface (single enable/disable function).
- rework bad block mark (now stored in OOB).
- fix stat reporting.
- rework FDM calculation.
- handle optional DT settings (strength, mode, ecc step size).
- spare per sector clamped to valid register values (hw spec).

Patch v3:
--------
mtd: mediatek: device tree docs for MTK Smart Device Gen1 NAND
- rename nandc (nand controller)

mtd: mediatek: driver for MTK Smart Device Gen1 NAND
- rename source and header files
- register definitions move to source files
- ecc interface dropped
- blank lines between functions (checkpatch.pl doesn't catch them)
- ecc_check function renamed ecc_get_stats
- ecc->dev assigned during probe()
- generic ecc control function replaced by individual functions
- required ecc parameters passed in ecc specific structures
- fix memory corruption (size 0 array)
- clarify nand offset/ptr function helpers (naming corrected)
- move ecc config call to select_chip()
- comment on hw issue workaround during read_byte
- implement write_buf
- remove switch_oob
- fix suspend/resume operation
- make nand-ecc-mode mandatory in device tree

RFC v2:
-------

mtd: mediatek: device tree docs for MTK Smart Device Gen1 NAND
- split nand flash interface and ecc engine

mtd: mediatek: driver for MTK Smart Device Gen1 NAND
- split host and ecc in two separate drivers.
- expose ecc layout through mtd_ooblayout_ops.
- fix wait loops.
- use device tree to describe ecc strength and ecc size.
- use device tree to describe CS.
- replace cmdfunc with cmd_ctrl.
- fix read byte interface.

dont enable controller in mt2701.dtsi
- requires additional device tree changes. This will be done in
the near future.

Overview:
=========

The following patch-set adds support for Mediatek's Smart Device
Gen1 NAND controller.

* Controller expected layout:
-----------------------------

The controller expects the OOB information relevant to each sector
within the page to follow immediately the data field.

For example for a 4KiB page with 1KiB sectors and 224B of OOB information,
the controller would expect the following layout.

-----------------------------------------------------
| 1KiB | 56B | 1KiB | 56B | 1KiB | 56B | 1KiB | 56B |
-----------------------------------------------------

This implies that the following actions are required:

- raw writes:
to match the controller expected layout, the driver uses the CPU and
a private bounce buffer to reassemble the page before the actual
writes.

- non raw writes:
ecc is hardware generated and data DMA'd in a single transfer.

Bad Block mark
==============
The bad block mark is stored in the OOB region (one byte)

Controller limitations:
=======================

* dma chaning not supported:
To guarantee that the pages corresponding to the buffers are contiguous
in memory the driver enables NAND_USE_BOUNCE_BUFFER.
* spare per sector: 16B to 128B
* sector sizes: 512B or 1024B
* programable page sizes: 512B, 2KB, 4KB, 8K, 16K

Tests:
======

* UBIFS support has been validated on 512MiB device (iozone, dd)
* All drivers/mtd/tests/* pass clean.
* Speed tests:

- eraseblock write speed : 7487 KiB/s
- eraseblock read speed : 10786 KiB/s
- page write speed : 7406 KiB/s
- page read speed : 10741 KiB/s
- 2 page write speed : 7447 KiB/s
- 2 page read speed : 10763 KiB/s
- erase speed : 105774 KiB/s
- 2x multi-block erase speed : 361120 KiB/s
- 4x multi-block erase speed : 362622 KiB/s
- 8x multi-block erase speed : 362622 KiB/s
- 16x multi-block erase speed : 363377 KiB/s
- 32x multi-block erase speed : 363377 KiB/s
- 64x multi-block erase speed : 363883 KiB/s

Jorge Ramirez-Ortiz (2):
mtd: mediatek: device tree docs for MTK Smart Device Gen1 NAND
mtd: mediatek: driver for MTK Smart Device Gen1 NAND

Documentation/devicetree/bindings/mtd/mtk-nand.txt | 161 +++
drivers/mtd/nand/Kconfig | 7 +
drivers/mtd/nand/Makefile | 1 +
drivers/mtd/nand/mtk_ecc.c | 527 +++++++
drivers/mtd/nand/mtk_ecc.h | 53 +
drivers/mtd/nand/mtk_nand.c | 1432 ++++++++++++++++++++
6 files changed, 2181 insertions(+)
create mode 100644 Documentation/devicetree/bindings/mtd/mtk-nand.txt
create mode 100644 drivers/mtd/nand/mtk_ecc.c
create mode 100644 drivers/mtd/nand/mtk_ecc.h
create mode 100644 drivers/mtd/nand/mtk_nand.c

--
2.7.4